Add SyncOptions as the second argument to Wallet::sync

The current options are awkware and it would be good if we could
introduce more in the future without breaking changes.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,26 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: 'bug'
+assignees: ''
+
+---
+
+**Describe the bug**  
+<!-- A clear and concise description of what the bug is. -->
+
+**To Reproduce**  
+<!-- Steps or code to reproduce the behavior. -->
+
+**Expected behavior**  
+<!-- A clear and concise description of what you expected to happen. -->
+
+**Build environment**  
+ - BDK tag/commit: <!-- e.g. v0.13.0, 3a07614 --> 
+ - OS+version: <!-- e.g. ubuntu 20.04.01, macOS 12.0.1, windows -->  
+ - Rust/Cargo version: <!-- e.g. 1.56.0 --> 
+ - Rust/Cargo target: <!-- e.g. x86_64-apple-darwin, x86_64-unknown-linux-gnu, etc. -->  
+
+**Additional context**  
+<!-- Add any other context about the problem here. --> 

.github/ISSUE_TEMPLATE/summer_project.md

@@ -0,0 +1,77 @@
+---
+name: Summer of Bitcoin Project
+about: Template to suggest a new https://www.summerofbitcoin.org/ project.
+title: ''
+labels: 'summer-of-bitcoin'
+assignees: ''
+
+---
+
+<!--
+## Overview  
+
+Project ideas are scoped for a university-level student with a basic background in CS and bitcoin 
+fundamentals - achievable over 12-weeks. Below are just a few types of ideas: 
+
+ - Low-hanging fruit: Relatively short projects with clear goals; requires basic technical knowledge 
+   and minimal familiarity with the codebase.
+ - Core development: These projects derive from the ongoing work from the core of your development 
+   team. The list of features and bugs is never-ending, and help is always welcome.
+ - Risky/Exploratory: These projects push the scope boundaries of your development effort. They 
+   might require expertise in an area not covered by your current development team. They might take 
+   advantage of a new technology. There is a reasonable chance that the project might be less 
+   successful, but the potential rewards make it worth the attempt.
+ - Infrastructure/Automation: These projects are the code that your organization uses to get its 
+   development work done; for example, projects that improve the automation of releases, regression 
+   tests and automated builds. This is a category where a Summer of Bitcoin student can be really 
+   helpful, doing work that the development team has been putting off while they focus on core 
+   development.
+ - Quality Assurance/Testing: Projects that work on and test your project's software development 
+   process. Additionally, projects that involve a thorough test and review of individual PRs.
+ - Fun/Peripheral: These projects might not be related to the current core development focus, but 
+   create new innovations and new perspectives for your project.
+-->
+
+**Description**
+<!-- Description: 3-7 sentences describing the project background and tasks to be done. -->  
+
+**Expected Outcomes**  
+<!-- Short bullet list describing what is to be accomplished -->   
+
+**Resources**  
+<!-- 2-3 reading materials for candidate to learn about the repo, project, scope etc -->  
+<!-- Recommended reading such as a developer/contributor guide -->  
+<!-- [Another example a paper citation](https://arxiv.org/pdf/1802.08091.pdf) -->  
+<!-- [Another example an existing issue](https://github.com/opencv/opencv/issues/11013) -->  
+<!-- [An existing related module](https://github.com/opencv/opencv_contrib/tree/master/modules/optflow) -->  
+
+**Skills Required**  
+<!-- 3-4 technical skills that the candidate should know -->  
+<!-- hands on experience with git -->  
+<!-- mastery plus experience coding in C++ -->  
+<!-- basic knowledge in matrix and tensor computations, college course work in cryptography -->  
+<!-- strong mathematical background -->
+<!-- Bonus - has experience with React Native. Best if you have also worked with OSSFuzz -->
+
+**Mentor(s)**  
+<!-- names of mentor(s) for this project go here -->
+
+**Difficulty**  
+<!-- Easy, Medium, Hard -->
+
+**Competency Test (optional)**  
+<!-- 2-3 technical tasks related to the project idea or repository you’d like a candidate to 
+    perform in order to demonstrate competency, good first bugs, warm-up exercises -->
+<!-- ex. Read the instructions here to get Bitcoin core running on your machine -->
+<!-- ex. pick an issue labeled as “newcomer” in the repository, and send a merge request to the 
+    repository. You can also suggest some other improvement that we did not think of yet, or 
+    something that you find interesting or useful -->
+<!-- ex. fixes for coding style are usually easy to do, and are good issues for first time 
+    contributions for those learning how to interact with the project. After you are done with the 
+    coding style issue, try making a different contribution. -->
+<!-- ex. setup a full Debian packaging development environment and learn the basics of Debian 
+    packaging. Then identify and package the missing dependencies to package Specter Desktop -->
+<!-- ex. write a pull parser for CSV files. You'll be judged by the decisions to store the parser 
+    state and how flexible it is to wrap this parser in other scenarios. -->
+<!-- ex. Stretch Goal: Implement some basic metaprogram/app to prove you're very familiar with BDK. 
+    Be prepared to make adjustments as we judge your solution. -->

.github/workflows/code_coverage.yml

@@ -24,14 +24,14 @@ jobs:
       - name: Update toolchain
         run: rustup update
       - name: Test
-        run: cargo test --features all-keys,compiler,esplora,compact_filters --no-default-features
+        run: cargo test --features all-keys,compiler,esplora,ureq,compact_filters --no-default-features
                     
       - id: coverage
         name: Generate coverage
         uses: actions-rs/grcov@v0.1.5
 
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v2
         with:
           file: ${{ steps.coverage.outputs.report }}
           directory: ./coverage/reports/

.github/workflows/cont_integration.yml

@@ -10,23 +10,29 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.51.0 # STABLE
-          - 1.46.0 # MSRV
+          - version: 1.56.0 # STABLE
+            clippy: true
+          - version: 1.46.0 # MSRV
         features:
           - default
           - minimal
           - all-keys
-          - minimal,esplora
+          - minimal,use-esplora-ureq
           - key-value-db
           - electrum
           - compact_filters
-          - esplora,key-value-db,electrum
+          - esplora,ureq,key-value-db,electrum
           - compiler
+          - rpc
+          - verify
+          - async-interface
+          - use-esplora-reqwest
+          - sqlite
     steps:
       - name: checkout
         uses: actions/checkout@v2
       - name: Generate cache key
-        run: echo "${{ matrix.rust }} ${{ matrix.features }}" | tee .cache_key
+        run: echo "${{ matrix.rust.version }} ${{ matrix.features }}" | tee .cache_key
       - name: cache
         uses: actions/cache@v2
         with:
@@ -36,16 +42,18 @@ jobs:
             target
           key: ${{ runner.os }}-cargo-${{ hashFiles('.cache_key') }}-${{ hashFiles('**/Cargo.toml','**/Cargo.lock') }}
       - name: Set default toolchain
-        run: rustup default ${{ matrix.rust }}
+        run: rustup default ${{ matrix.rust.version }}
       - name: Set profile
         run: rustup set profile minimal
       - name: Add clippy
+        if: ${{ matrix.rust.clippy }}
         run: rustup component add clippy
       - name: Update toolchain
         run: rustup update
       - name: Build
         run: cargo build --features ${{ matrix.features }} --no-default-features
       - name: Clippy
+        if: ${{ matrix.rust.clippy }}
         run: cargo clippy --all-targets --features ${{ matrix.features }} --no-default-features -- -D warnings
       - name: Test
         run: cargo test --features ${{ matrix.features }} --no-default-features
@@ -74,26 +82,20 @@ jobs:
         run: cargo test --features test-md-docs --no-default-features -- doctest::ReadmeDoctests
 
   test-blockchains:
-    name: Test ${{ matrix.blockchain.name }}
-    runs-on: ubuntu-16.04
+    name: Blockchain ${{ matrix.blockchain.features }}
+    runs-on: ubuntu-20.04
     strategy:
+      fail-fast: false
       matrix:
         blockchain:
           - name: electrum
-            container: bitcoindevkit/electrs
-            start: /root/electrs --network regtest --jsonrpc-import
+            features: test-electrum
+          - name: rpc
+            features: test-rpc
           - name: esplora
-            container: bitcoindevkit/esplora
-            start: /root/electrs --network regtest -vvv --cookie admin:passw --jsonrpc-import --electrum-rpc-addr=0.0.0.0:60401 --http-addr 0.0.0.0:3002
-    container: ${{ matrix.blockchain.container }}
-    env:
-      BDK_RPC_AUTH: USER_PASS
-      BDK_RPC_USER: admin
-      BDK_RPC_PASS: passw
-      BDK_RPC_URL: 127.0.0.1:18443
-      BDK_RPC_WALLET: bdk-test
-      BDK_ELECTRUM_URL: tcp://127.0.0.1:60401
-      BDK_ESPLORA_URL: http://127.0.0.1:3002
+            features: test-esplora,use-esplora-reqwest
+          - name: esplora
+            features: test-esplora,use-esplora-ureq    
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -105,26 +107,17 @@ jobs:
             ~/.cargo/git
             target
           key: ${{ runner.os }}-cargo-${{ github.job }}-${{ hashFiles('**/Cargo.toml','**/Cargo.lock') }}
-      - name: get pkg-config # running eslpora tests seems to need this
-        run: apt update && apt install -y --fix-missing pkg-config libssl-dev
-      - name: Install rustup
-        run: curl https://sh.rustup.rs -sSf | sh -s -- -y
-      - name: Set default toolchain
-        run: $HOME/.cargo/bin/rustup default 1.51.0 # STABLE
-      - name: Set profile
-        run: $HOME/.cargo/bin/rustup set profile minimal
-      - name: Update toolchain
-        run: $HOME/.cargo/bin/rustup update
-      - name: Start core
-        run: ./ci/start-core.sh
-      - name: start ${{ matrix.blockchain.name }}
-        run: nohup ${{ matrix.blockchain.start }} & sleep 5
+      - name: Setup rust toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
       - name: Test
-        run: $HOME/.cargo/bin/cargo test --features ${{ matrix.blockchain.name }},test-blockchains --no-default-features ${{ matrix.blockchain.name }}::bdk_blockchain_tests
-
+        run: cargo test --no-default-features --features ${{ matrix.blockchain.features }} ${{ matrix.blockchain.name }}::bdk_blockchain_tests
+  
   check-wasm:
     name: Check WASM
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-20.04
     env:
       CC: clang-10
       CFLAGS: -I/usr/include
@@ -141,11 +134,11 @@ jobs:
           key: ${{ runner.os }}-cargo-${{ github.job }}-${{ hashFiles('**/Cargo.toml','**/Cargo.lock') }}
         # Install a recent version of clang that supports wasm32
       - run: wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add - || exit 1
-      - run: sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-10 main" || exit 1
+      - run: sudo apt-add-repository "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-10 main" || exit 1
       - run: sudo apt-get update || exit 1
       - run: sudo apt-get install -y libclang-common-10-dev clang-10 libc6-dev-i386 || exit 1
       - name: Set default toolchain
-        run: rustup default 1.51.0 # STABLE
+        run: rustup default 1.56.0 # STABLE
       - name: Set profile
         run: rustup set profile minimal
       - name: Add target wasm32
@@ -153,7 +146,7 @@ jobs:
       - name: Update toolchain
         run: rustup update
       - name: Check
-        run: cargo check --target wasm32-unknown-unknown --features esplora --no-default-features
+        run: cargo check --target wasm32-unknown-unknown --features use-esplora-reqwest --no-default-features
 
   fmt:
     name: Rust fmt

.github/workflows/nightly_docs.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Update toolchain
         run: rustup update
       - name: Build docs
-        run: cargo rustdoc --verbose --features=compiler,electrum,esplora,compact_filters,key-value-db,all-keys -- --cfg docsrs -Dwarnings
+        run: cargo rustdoc --verbose --features=compiler,electrum,esplora,ureq,compact_filters,key-value-db,all-keys,sqlite -- --cfg docsrs -Dwarnings
       - name: Upload artifact
         uses: actions/upload-artifact@v2
         with:
@@ -44,18 +44,18 @@ jobs:
           repository: bitcoindevkit/bitcoindevkit.org
           ref: master
       - name: Create directories
-        run: mkdir -p ./static/docs-rs/bdk/nightly
+        run: mkdir -p ./docs/.vuepress/public/docs-rs/bdk/nightly
       - name: Remove old latest
-        run: rm -rf ./static/docs-rs/bdk/nightly/latest
+        run: rm -rf ./docs/.vuepress/public/docs-rs/bdk/nightly/latest
       - name: Download built docs
         uses: actions/download-artifact@v1
         with:
           name: built-docs
-          path: ./static/docs-rs/bdk/nightly/latest
+          path: ./docs/.vuepress/public/docs-rs/bdk/nightly/latest
       - name: Configure git
         run: git config user.email "github-actions@github.com" && git config user.name "github-actions"
       - name: Commit
         continue-on-error: true         # If there's nothing to commit this step fails, but it's fine
-        run: git add ./static && git commit -m "Publish autogenerated nightly docs"
+        run: git add ./docs/.vuepress/public/docs-rs && git commit -m "Publish autogenerated nightly docs"
       - name: Push
         run: git push origin master

CHANGELOG.md

@@ -6,6 +6,68 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Sync API change
+
+To decouple the `Wallet` from the `Blockchain` we've made major changes:
+
+- Removed `Blockchain` from Wallet.
+- Removed `Wallet::broadcast` (just use `Blockchain::broadcast`)
+- Depreciated `Wallet::new_offline` (all wallets are offline now)
+- Changed `Wallet::sync` to take a `Blockchain`.
+- Stop making a request for the block height when calling `Wallet:new`.
+- Added `SyncOptions` to capture extra (future) arguments to `Wallet::sync`.
+
+## [v0.15.0] - [v0.14.0]
+
+- Overhauled sync logic for electrum and esplora.
+- Unify ureq and reqwest esplora backends to have the same configuration parameters. This means reqwest now has a timeout parameter and ureq has a concurrency parameter.
+- Fixed esplora fee estimation.
+- Fixed generating WIF in the correct network format.
+- Disable `reqwest` default features.
+- Added `reqwest-default-tls` feature: Use this to restore the TLS defaults of reqwest if you don't want to add a dependency to it in your own manifest.
+
+## [v0.14.0] - [v0.13.0]
+
+- BIP39 implementation dependency, in `keys::bip39` changed from tiny-bip39 to rust-bip39.
+- Add new method on the `TxBuilder` to embed data in the transaction via `OP_RETURN`. To allow that a fix to check the dust only on spendable output has been introduced.
+- Update the `Database` trait to store the last sync timestamp and block height
+- Rename `ConfirmationTime` to `BlockTime`
+
+## [v0.13.0] - [v0.12.0]
+
+- Exposed `get_tx()` method from `Database` to `Wallet`.
+
+## [v0.12.0] - [v0.11.0]
+
+- Activate `miniscript/use-serde` feature to allow consumers of the library to access it via the re-exported `miniscript` crate.
+- Add support for proxies in `EsploraBlockchain`
+- Added `SqliteDatabase` that implements `Database` backed by a sqlite database using `rusqlite` crate.
+
+## [v0.11.0] - [v0.10.0]
+
+- Added `flush` method to the `Database` trait to explicitly flush to disk latest changes on the db.
+
+## [v0.10.0] - [v0.9.0]
+
+- Added `RpcBlockchain` in the `AnyBlockchain` struct to allow using Rpc backend where `AnyBlockchain` is used (eg `bdk-cli`)
+- Removed hard dependency on `tokio`.
+
+### Wallet
+
+- Removed and replaced `set_single_recipient` with more general `drain_to` and replaced `maintain_single_recipient` with `allow_shrinking`.
+
+### Blockchain
+
+- Removed `stop_gap` from `Blockchain` trait and added it to only `ElectrumBlockchain` and `EsploraBlockchain` structs.
+- Added a `ureq` backend for use when not using feature `async-interface` or target WASM. `ureq` is a blocking HTTP client.
+
+## [v0.9.0] - [v0.8.0]
+
+### Wallet
+
+- Added Bitcoin core RPC added as blockchain backend
+- Added a `verify` feature that can be enable to verify the unconfirmed txs we download against the consensus rules
+
 ## [v0.8.0] - [v0.7.0]
 
 ### Wallet
@@ -339,7 +401,7 @@ final transaction is created by calling `finish` on the builder.
 - Use `MemoryDatabase` in the compiler example
 - Make the REPL return JSON
 
-[unreleased]: https://github.com/bitcoindevkit/bdk/compare/v0.4.0...HEAD
+[unreleased]: https://github.com/bitcoindevkit/bdk/compare/v0.11.0...HEAD
 [0.1.0-beta.1]: https://github.com/bitcoindevkit/bdk/compare/96c87ea5...0.1.0-beta.1
 [v0.2.0]: https://github.com/bitcoindevkit/bdk/compare/0.1.0-beta.1...v0.2.0
 [v0.3.0]: https://github.com/bitcoindevkit/bdk/compare/v0.2.0...v0.3.0
@@ -348,3 +410,11 @@ final transaction is created by calling `finish` on the builder.
 [v0.5.1]: https://github.com/bitcoindevkit/bdk/compare/v0.5.0...v0.5.1
 [v0.6.0]: https://github.com/bitcoindevkit/bdk/compare/v0.5.1...v0.6.0
 [v0.7.0]: https://github.com/bitcoindevkit/bdk/compare/v0.6.0...v0.7.0
+[v0.8.0]: https://github.com/bitcoindevkit/bdk/compare/v0.7.0...v0.8.0
+[v0.9.0]: https://github.com/bitcoindevkit/bdk/compare/v0.8.0...v0.9.0
+[v0.10.0]: https://github.com/bitcoindevkit/bdk/compare/v0.9.0...v0.10.0
+[v0.11.0]: https://github.com/bitcoindevkit/bdk/compare/v0.10.0...v0.11.0
+[v0.12.0]: https://github.com/bitcoindevkit/bdk/compare/v0.11.0...v0.12.0
+[v0.13.0]: https://github.com/bitcoindevkit/bdk/compare/v0.12.0...v0.13.0
+[v0.14.0]: https://github.com/bitcoindevkit/bdk/compare/v0.13.0...v0.14.0
+[v0.15.0]: https://github.com/bitcoindevkit/bdk/compare/v0.14.0...v0.15.0

CONTRIBUTING.md

@@ -57,6 +57,21 @@ comment suggesting that you're working on it. If someone is already assigned,
 don't hesitate to ask if the assigned party or previous commenters are still
 working on it if it has been awhile.
 
+Deprecation policy
+------------------
+
+Where possible, breaking existing APIs should be avoided. Instead, add new APIs and
+use [`#[deprecated]`](https://github.com/rust-lang/rfcs/blob/master/text/1270-deprecation.md)
+to discourage use of the old one.
+
+Deprecated APIs are typically maintained for one release cycle. In other words, an
+API that has been deprecated with the 0.10 release can be expected to be removed in the
+0.11 release. This allows for smoother upgrades without incurring too much technical
+debt inside this library.
+
+If you deprecated an API as part of a contribution, we encourage you to "own" that API
+and send a follow-up to remove it as part of the next release cycle.
+
 Peer review
 -----------
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bdk"
-version = "0.8.0"
+version = "0.15.1-dev"
 edition = "2018"
 authors = ["Alekos Filini <alekos.filini@gmail.com>", "Riccardo Casatta <riccardo@casatta.it>"]
 homepage = "https://bitcoindevkit.org"
@@ -12,29 +12,33 @@ readme = "README.md"
 license = "MIT OR Apache-2.0"
 
 [dependencies]
-bdk-macros = "^0.4"
+bdk-macros = "^0.6"
 log = "^0.4"
-miniscript = "5.1"
-bitcoin = { version = "^0.26", features = ["use-serde"] }
+miniscript = { version = "^6.0", features = ["use-serde"] }
+bitcoin = { version = "^0.27", features = ["use-serde", "base64"] }
 serde = { version = "^1.0", features = ["derive"] }
 serde_json = { version = "^1.0" }
 rand = "^0.7"
 
 # Optional dependencies
 sled = { version = "0.34", optional = true }
-electrum-client = { version = "0.7", optional = true }
-reqwest = { version = "0.11", optional = true, features = ["json"] }
+electrum-client = { version = "0.8", optional = true }
+rusqlite = { version = "0.25.3", optional = true }
+ahash = { version = "=0.7.4", optional = true }
+reqwest = { version = "0.11", optional = true, default-features = false, features = ["json"] }
+ureq = { version = "~2.2.0", features = ["json"], optional = true }
 futures = { version = "0.3", optional = true }
 async-trait = { version = "0.1", optional = true }
-rocksdb = { version = "0.14", optional = true }
+rocksdb = { version = "0.14", default-features = false, features = ["snappy"], optional = true }
 cc = { version = ">=1.0.64", optional = true }
 socks = { version = "0.3", optional = true }
 lazy_static = { version = "1.4", optional = true }
-tiny-bip39 = { version = "^0.8", optional = true }
+
+bip39 = { version = "1.0.1", optional = true }
+bitcoinconsensus = { version = "0.19.0-3", optional = true }
 
 # Needed by bdk_blockchain_tests macro
-bitcoincore-rpc = {  version = "0.13", optional = true }
-serial_test = { version = "0.4", optional = true }
+bitcoincore-rpc = { version = "0.14", optional = true }
 
 # Platform-specific dependencies
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
@@ -48,25 +52,51 @@ rand = { version = "^0.7", features = ["wasm-bindgen"] }
 [features]
 minimal = []
 compiler = ["miniscript/compiler"]
+verify = ["bitcoinconsensus"]
 default = ["key-value-db", "electrum"]
-electrum = ["electrum-client"]
-esplora = ["reqwest", "futures"]
+sqlite = ["rusqlite", "ahash"]
 compact_filters = ["rocksdb", "socks", "lazy_static", "cc"]
 key-value-db = ["sled"]
-async-interface = ["async-trait"]
 all-keys = ["keys-bip39"]
-keys-bip39 = ["tiny-bip39"]
+keys-bip39 = ["bip39"]
+rpc = ["bitcoincore-rpc"]
+
+# We currently provide mulitple implementations of `Blockchain`, all are
+# blocking except for the `EsploraBlockchain` which can be either async or
+# blocking, depending on the HTTP client in use.
+#
+# - Users wanting asynchronous HTTP calls should enable `async-interface` to get
+#   access to the asynchronous method implementations. Then, if Esplora is wanted,
+#   enable `esplora` AND `reqwest` (`--features=use-esplora-reqwest`).
+# - Users wanting blocking HTTP calls can use any of the other blockchain
+#   implementations (`compact_filters`, `electrum`, or `esplora`). Users wanting to
+#   use Esplora should enable `esplora` AND `ureq`  (`--features=use-esplora-ureq`).
+#
+# WARNING: Please take care with the features below, various combinations will
+# fail to build. We cannot currently build `bdk` with `--all-features`.
+async-interface = ["async-trait"]
+electrum = ["electrum-client"]
+# MUST ALSO USE `--no-default-features`.
+use-esplora-reqwest = ["esplora", "reqwest", "reqwest/socks", "futures"]
+use-esplora-ureq = ["esplora", "ureq", "ureq/socks"]
+# Typical configurations will not need to use `esplora` feature directly.
+esplora = []
+
+# Use below feature with `use-esplora-reqwest` to enable reqwest default TLS support
+reqwest-default-tls = ["reqwest/default-tls"]
 
 # Debug/Test features
 test-blockchains = ["bitcoincore-rpc", "electrum-client"]
+test-electrum = ["electrum", "electrsd/electrs_0_8_10", "test-blockchains"]
+test-rpc = ["rpc", "electrsd/electrs_0_8_10", "test-blockchains"]
+test-esplora = ["electrsd/legacy", "electrsd/esplora_a33e97e1", "test-blockchains"]
 test-md-docs = ["electrum"]
 
 [dev-dependencies]
 lazy_static = "1.4"
 env_logger = "0.7"
-base64 = "^0.11"
 clap = "2.33"
-serial_test = "0.4"
+electrsd = { version= "0.13", features = ["trigger", "bitcoind_22_0"] }
 
 [[example]]
 name = "address_validator"
@@ -82,6 +112,6 @@ required-features = ["compiler"]
 [workspace]
 members = ["macros"]
 [package.metadata.docs.rs]
-features = ["compiler", "electrum", "esplora", "compact_filters", "key-value-db", "all-keys"]
+features = ["compiler", "electrum", "esplora", "ureq", "compact_filters", "rpc", "key-value-db", "sqlite", "all-keys", "verify"]
 # defines the configuration attribute `docsrs`
 rustdoc-args = ["--cfg", "docsrs"]

DEVELOPMENT_CYCLE.md

@@ -32,14 +32,14 @@ Pre-`v1.0.0` our "major" releases only affect the "minor" semver value. Accordin
     - If it's a minor issue you can just fix it in the release branch, since it will be merged back to `master` eventually
     - For bigger issues you can fix them on `master` and then *cherry-pick* the commit to the release branch
 6. Update the changelog with the new release version.
-7. Update `src/lib.rs` with the new version (line ~59)
+7. Update `src/lib.rs` with the new version (line ~43)
 8. On release day, make a commit on the release branch to bump the version to `x.y.z`. The message should be "Bump version to x.y.z".
 9. Add a tag to this commit. The tag name should be `vx.y.z` (for example `v0.5.0`), and the message "Release x.y.z". Make sure the tag is signed, for extra safety use the explicit `--sign` flag.
 10. Push the new commits to the upstream release branch, wait for the CI to finish one last time.
 11. Publish **all** the updated crates to crates.io.
 12. Make a new commit to bump the version value to `x.y.(z+1)-dev`. The message should be "Bump version to x.y.(z+1)-dev".
 13. Merge the release branch back into `master`.
-14. If the `master` branch contains any unreleased changes to the `bdk-macros`, `bdk-testutils`, or `bdk-testutils-macros` crates, change the `bdk` Cargo.toml `[dev-dependencies]` to point to the local path (ie. `bdk-testutils-macros = { path = "./testutils-macros"}`)
+14. If the `master` branch contains any unreleased changes to the `bdk-macros` crate, change the `bdk` Cargo.toml `[dependencies]` to point to the local path (ie. `bdk-macros = { path = "./macros"}`)
 15. Create the release on GitHub: go to "tags", click on the dots on the right and select "Create Release". Then set the title to `vx.y.z` and write down some brief release notes.
 16. Make sure the new release shows up on crates.io and that the docs are built correctly on docs.rs.
 17. Announce the release on Twitter, Discord and Telegram.

README.md

@@ -1,7 +1,7 @@
 <div align="center">
   <h1>BDK</h1>
 
-  <img src="./static/bdk.svg" width="220" />
+  <img src="./static/bdk.png" width="220" />
 
   <p>
     <strong>A modern, lightweight, descriptor-based wallet library written in Rust!</strong>
@@ -41,21 +41,21 @@ The `bdk` library aims to be the core building block for Bitcoin wallets of any
 ```rust,no_run
 use bdk::Wallet;
 use bdk::database::MemoryDatabase;
-use bdk::blockchain::{noop_progress, ElectrumBlockchain};
+use bdk::blockchain::ElectrumBlockchain;
+use bdk::SyncOptions;
 
 use bdk::electrum_client::Client;
 
 fn main() -> Result<(), bdk::Error> {
-    let client = Client::new("ssl://electrum.blockstream.info:60002")?;
+    let blockchain = ElectrumBlockchain::from(Client::new("ssl://electrum.blockstream.info:60002")?);
     let wallet = Wallet::new(
         "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/0/*)",
         Some("wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"),
         bitcoin::Network::Testnet,
         MemoryDatabase::default(),
-        ElectrumBlockchain::from(client)
     )?;
 
-    wallet.sync(noop_progress(), None)?;
+    wallet.sync(&blockchain, SyncOptions::default())?;
 
     println!("Descriptor balance: {} SAT", wallet.get_balance()?);
 
@@ -70,7 +70,7 @@ use bdk::{Wallet, database::MemoryDatabase};
 use bdk::wallet::AddressIndex::New;
 
 fn main() -> Result<(), bdk::Error> {
-    let wallet = Wallet::new_offline(
+    let wallet = Wallet::new(
         "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/0/*)",
         Some("wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"),
         bitcoin::Network::Testnet,
@@ -88,9 +88,9 @@ fn main() -> Result<(), bdk::Error> {
 ### Create a transaction
 
 ```rust,no_run
-use bdk::{FeeRate, Wallet};
+use bdk::{FeeRate, Wallet, SyncOptions};
 use bdk::database::MemoryDatabase;
-use bdk::blockchain::{noop_progress, ElectrumBlockchain};
+use bdk::blockchain::ElectrumBlockchain;
 
 use bdk::electrum_client::Client;
 use bdk::wallet::AddressIndex::New;
@@ -98,16 +98,15 @@ use bdk::wallet::AddressIndex::New;
 use bitcoin::consensus::serialize;
 
 fn main() -> Result<(), bdk::Error> {
-    let client = Client::new("ssl://electrum.blockstream.info:60002")?;
+    let blockchain = ElectrumBlockchain::from(Client::new("ssl://electrum.blockstream.info:60002")?);
     let wallet = Wallet::new(
         "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/0/*)",
         Some("wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"),
         bitcoin::Network::Testnet,
         MemoryDatabase::default(),
-        ElectrumBlockchain::from(client)
     )?;
 
-    wallet.sync(noop_progress(), None)?;
+    wallet.sync(&blockchain, SyncOptions::default())?;
 
     let send_to = wallet.get_address(New)?;
     let (psbt, details) = {
@@ -135,7 +134,7 @@ use bdk::{Wallet, SignOptions, database::MemoryDatabase};
 use bitcoin::consensus::deserialize;
 
 fn main() -> Result<(), bdk::Error> {
-    let wallet = Wallet::new_offline(
+    let wallet = Wallet::new(
         "wpkh([c258d2e4/84h/1h/0h]tprv8griRPhA7342zfRyB6CqeKF8CJDXYu5pgnj1cjL1u2ngKcJha5jjTRimG82ABzJQ4MQe71CV54xfn25BbhCNfEGGJZnxvCDQCd6JkbvxW6h/0/*)",
         Some("wpkh([c258d2e4/84h/1h/0h]tprv8griRPhA7342zfRyB6CqeKF8CJDXYu5pgnj1cjL1u2ngKcJha5jjTRimG82ABzJQ4MQe71CV54xfn25BbhCNfEGGJZnxvCDQCd6JkbvxW6h/1/*)"),
         bitcoin::Network::Testnet,
@@ -151,6 +150,25 @@ fn main() -> Result<(), bdk::Error> {
 }
 ```
 
+## Testing
+
+### Unit testing
+
+```
+cargo test
+```
+
+### Integration testing
+
+Integration testing require testing features, for example:
+
+```
+cargo test --features test-electrum
+```
+
+The other options are `test-esplora` or `test-rpc`.
+Note that `electrs` and `bitcoind` binaries are automatically downloaded (on mac and linux), to specify you already have installed binaries you must use `--no-default-features` and provide `BITCOIND_EXE` and `ELECTRS_EXE` as environment variables.
+
 ## License
 
 Licensed under either of

ci/start-core.sh

@@ -1,13 +1,14 @@
 #!/usr/bin/env sh
 
 echo "Starting bitcoin node."
-/root/bitcoind -regtest -server -daemon -fallbackfee=0.0002 -rpcuser=$BDK_RPC_USER -rpcpassword=$BDK_RPC_PASS -rpcallowip=0.0.0.0/0 -rpcbind=0.0.0.0 -blockfilterindex=1 -peerblockfilters=1
+mkdir $GITHUB_WORKSPACE/.bitcoin
+/root/bitcoind -regtest -server -daemon -datadir=$GITHUB_WORKSPACE/.bitcoin -fallbackfee=0.0002 -rpcallowip=0.0.0.0/0 -rpcbind=0.0.0.0 -blockfilterindex=1 -peerblockfilters=1
 
 echo "Waiting for bitcoin node."
-until /root/bitcoin-cli -regtest -rpcuser=$BDK_RPC_USER -rpcpassword=$BDK_RPC_PASS getblockchaininfo; do
+until /root/bitcoin-cli -regtest -datadir=$GITHUB_WORKSPACE/.bitcoin getblockchaininfo; do
     sleep 1
 done
-/root/bitcoin-cli -regtest -rpcuser=$BDK_RPC_USER -rpcpassword=$BDK_RPC_PASS createwallet $BDK_RPC_WALLET
+/root/bitcoin-cli -regtest -datadir=$GITHUB_WORKSPACE/.bitcoin createwallet $BDK_RPC_WALLET
 echo "Generating 150 bitcoin blocks."
-ADDR=$(/root/bitcoin-cli -regtest -rpcuser=$BDK_RPC_USER -rpcpassword=$BDK_RPC_PASS -rpcwallet=$BDK_RPC_WALLET getnewaddress)
-/root/bitcoin-cli -regtest -rpcuser=$BDK_RPC_USER -rpcpassword=$BDK_RPC_PASS generatetoaddress 150 $ADDR
+ADDR=$(/root/bitcoin-cli -regtest -datadir=$GITHUB_WORKSPACE/.bitcoin -rpcwallet=$BDK_RPC_WALLET getnewaddress)
+/root/bitcoin-cli -regtest -datadir=$GITHUB_WORKSPACE/.bitcoin generatetoaddress 150 $ADDR

examples/address_validator.rs

@@ -48,8 +48,7 @@ impl AddressValidator for DummyValidator {
 
 fn main() -> Result<(), bdk::Error> {
     let descriptor = "sh(and_v(v:pk(tpubDDpWvmUrPZrhSPmUzCMBHffvC3HyMAPnWDSAQNBTnj1iZeJa7BZQEttFiP4DS4GCcXQHezdXhn86Hj6LHX5EDstXPWrMaSneRWM8yUf6NFd/*),after(630000)))";
-    let mut wallet =
-        Wallet::new_offline(descriptor, None, Network::Regtest, MemoryDatabase::new())?;
+    let mut wallet = Wallet::new(descriptor, None, Network::Regtest, MemoryDatabase::new())?;
 
     wallet.add_address_validator(Arc::new(DummyValidator));
 

examples/compact_filters_balance.rs

@@ -10,7 +10,6 @@
 // licenses.
 
 use bdk::blockchain::compact_filters::*;
-use bdk::blockchain::noop_progress;
 use bdk::database::MemoryDatabase;
 use bdk::*;
 use bitcoin::*;
@@ -35,9 +34,8 @@ fn main() -> Result<(), CompactFiltersError> {
     let descriptor = "wpkh(tpubD6NzVbkrYhZ4X2yy78HWrr1M9NT8dKeWfzNiQqDdMqqa9UmmGztGGz6TaLFGsLfdft5iu32gxq1T4eMNxExNNWzVCpf9Y6JZi5TnqoC9wJq/*)";
 
     let database = MemoryDatabase::default();
-    let wallet =
-        Arc::new(Wallet::new(descriptor, None, Network::Testnet, database, blockchain).unwrap());
-    wallet.sync(noop_progress(), None).unwrap();
+    let wallet = Arc::new(Wallet::new(descriptor, None, Network::Testnet, database).unwrap());
+    wallet.sync(&blockchain, SyncOptions::default()).unwrap();
     info!("balance: {}", wallet.get_balance()?);
     Ok(())
 }

examples/compiler.rs

@@ -70,7 +70,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     let policy_str = matches.value_of("POLICY").unwrap();
     info!("Compiling policy: {}", policy_str);
 
-    let policy = Concrete::<String>::from_str(&policy_str)?;
+    let policy = Concrete::<String>::from_str(policy_str)?;
 
     let descriptor = match matches.value_of("TYPE").unwrap() {
         "sh" => Descriptor::new_sh(policy.compile()?)?,
@@ -89,7 +89,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         .transpose()
         .unwrap()
         .unwrap_or(Network::Testnet);
-    let wallet = Wallet::new_offline(&format!("{}", descriptor), None, network, database)?;
+    let wallet = Wallet::new(&format!("{}", descriptor), None, network, database)?;
 
     info!("... First address: {}", wallet.get_address(New)?);
 

macros/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "bdk-macros"
-version = "0.4.0"
+version = "0.6.0"
 authors = ["Alekos Filini <alekos.filini@gmail.com>"]
 edition = "2018"
 homepage = "https://bitcoindevkit.org"

run_blockchain_tests.sh

@@ -1,64 +0,0 @@
-#!/bin/sh
-
-usage() {
-    cat <<'EOF'
-Script for running the bdk blockchain tests for a specific blockchain by starting up the backend in docker.
-
-Usage: ./run_blockchain_tests.sh [esplora|electrum] [test name].
-
-EOF
-}
-
-eprintln(){
-    echo "$@" >&2
-}
-
-cleanup() {
-    if test "$id"; then
-        eprintln "cleaning up $blockchain docker container $id";
-        docker rm -fv "$id" > /dev/null;
-    fi
-    trap - EXIT INT
-}
-
-# Makes sure we clean up the container at the end or if ^C
-trap 'rc=$?; cleanup; exit $rc' EXIT INT
-
-blockchain="$1"
-test_name="$2"
-
-case "$blockchain" in
-    electrum)
-        eprintln "starting electrs docker container"
-        id="$(docker run -d -p 127.0.0.1:18443-18444:18443-18444/tcp -p 127.0.0.1:60401:60401/tcp bitcoindevkit/electrs)"
-        ;;
-    esplora)
-        eprintln "starting esplora docker container"
-        id="$(docker run -d -p 127.0.0.1:18443-18444:18443-18444/tcp -p 127.0.0.1:60401:60401/tcp -p 127.0.0.1:3002:3002/tcp bitcoindevkit/esplora)"
-        export BDK_ESPLORA_URL=http://127.0.0.1:3002
-        ;;
-    *)
-        usage;
-        exit 1;
-        ;;
-    esac
-
-# taken from https://github.com/bitcoindevkit/bitcoin-regtest-box
-export BDK_RPC_AUTH=USER_PASS
-export BDK_RPC_USER=admin
-export BDK_RPC_PASS=passw
-export BDK_RPC_URL=127.0.0.1:18443
-export BDK_RPC_WALLET=bdk-test
-export BDK_ELECTRUM_URL=tcp://127.0.0.1:60401
-
-cli(){
-    docker exec -it "$id" /root/bitcoin-cli -regtest -rpcuser=admin -rpcpassword=passw $@
-}
-
-eprintln "running getwalletinfo until bitcoind seems to be alive"
-while ! cli getwalletinfo >/dev/null; do sleep 1; done
-
-# sleep again for good measure!
-sleep 1;
-
-cargo test --features "test-blockchains,$blockchain" --no-default-features "$blockchain::bdk_blockchain_tests::$test_name"

src/blockchain/any.rs

@@ -16,59 +16,18 @@
 //!
 //! ## Example
 //!
-//! In this example both `wallet_electrum` and `wallet_esplora` have the same type of
-//! `Wallet<AnyBlockchain, MemoryDatabase>`. This means that they could both, for instance, be
-//! assigned to a struct member.
-//!
-//! ```no_run
-//! # use bitcoin::Network;
-//! # use bdk::blockchain::*;
-//! # use bdk::database::MemoryDatabase;
-//! # use bdk::Wallet;
-//! # #[cfg(feature = "electrum")]
-//! # {
-//! let electrum_blockchain = ElectrumBlockchain::from(electrum_client::Client::new("...")?);
-//! let wallet_electrum: Wallet<AnyBlockchain, _> = Wallet::new(
-//!     "...",
-//!     None,
-//!     Network::Testnet,
-//!     MemoryDatabase::default(),
-//!     electrum_blockchain.into(),
-//! )?;
-//! # }
-//!
-//! # #[cfg(feature = "esplora")]
-//! # {
-//! let esplora_blockchain = EsploraBlockchain::new("...", None);
-//! let wallet_esplora: Wallet<AnyBlockchain, _> = Wallet::new(
-//!     "...",
-//!     None,
-//!     Network::Testnet,
-//!     MemoryDatabase::default(),
-//!     esplora_blockchain.into(),
-//! )?;
-//! # }
-//!
-//! # Ok::<(), bdk::Error>(())
-//! ```
-//!
 //! When paired with the use of [`ConfigurableBlockchain`], it allows creating wallets with any
 //! blockchain type supported using a single line of code:
 //!
 //! ```no_run
 //! # use bitcoin::Network;
 //! # use bdk::blockchain::*;
-//! # use bdk::database::MemoryDatabase;
-//! # use bdk::Wallet;
+//! # #[cfg(all(feature = "esplora", feature = "ureq"))]
+//! # {
 //! let config = serde_json::from_str("...")?;
 //! let blockchain = AnyBlockchain::from_config(&config)?;
-//! let wallet = Wallet::new(
-//!     "...",
-//!     None,
-//!     Network::Testnet,
-//!     MemoryDatabase::default(),
-//!     blockchain,
-//! )?;
+//! let height = blockchain.get_height();
+//! # }
 //! # Ok::<(), bdk::Error>(())
 //! ```
 
@@ -94,6 +53,8 @@ macro_rules! impl_inner_method {
             AnyBlockchain::Esplora(inner) => inner.$name( $($args, )* ),
             #[cfg(feature = "compact_filters")]
             AnyBlockchain::CompactFilters(inner) => inner.$name( $($args, )* ),
+            #[cfg(feature = "rpc")]
+            AnyBlockchain::Rpc(inner) => inner.$name( $($args, )* ),
         }
     }
 }
@@ -116,6 +77,10 @@ pub enum AnyBlockchain {
     #[cfg_attr(docsrs, doc(cfg(feature = "compact_filters")))]
     /// Compact filters client
     CompactFilters(compact_filters::CompactFiltersBlockchain),
+    #[cfg(feature = "rpc")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rpc")))]
+    /// RPC client
+    Rpc(rpc::RpcBlockchain),
 }
 
 #[maybe_async]
@@ -124,35 +89,6 @@ impl Blockchain for AnyBlockchain {
         maybe_await!(impl_inner_method!(self, get_capabilities))
     }
 
-    fn setup<D: BatchDatabase, P: 'static + Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error> {
-        maybe_await!(impl_inner_method!(
-            self,
-            setup,
-            stop_gap,
-            database,
-            progress_update
-        ))
-    }
-    fn sync<D: BatchDatabase, P: 'static + Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error> {
-        maybe_await!(impl_inner_method!(
-            self,
-            sync,
-            stop_gap,
-            database,
-            progress_update
-        ))
-    }
-
     fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
         maybe_await!(impl_inner_method!(self, get_tx, txid))
     }
@@ -160,17 +96,49 @@ impl Blockchain for AnyBlockchain {
         maybe_await!(impl_inner_method!(self, broadcast, tx))
     }
 
+    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
+        maybe_await!(impl_inner_method!(self, estimate_fee, target))
+    }
+}
+
+impl GetHeight for AnyBlockchain {
     fn get_height(&self) -> Result<u32, Error> {
         maybe_await!(impl_inner_method!(self, get_height))
     }
-    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
-        maybe_await!(impl_inner_method!(self, estimate_fee, target))
+}
+
+impl WalletSync for AnyBlockchain {
+    fn wallet_sync<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        maybe_await!(impl_inner_method!(
+            self,
+            wallet_sync,
+            database,
+            progress_update
+        ))
+    }
+
+    fn wallet_setup<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        maybe_await!(impl_inner_method!(
+            self,
+            wallet_setup,
+            database,
+            progress_update
+        ))
     }
 }
 
 impl_from!(electrum::ElectrumBlockchain, AnyBlockchain, Electrum, #[cfg(feature = "electrum")]);
 impl_from!(esplora::EsploraBlockchain, AnyBlockchain, Esplora, #[cfg(feature = "esplora")]);
 impl_from!(compact_filters::CompactFiltersBlockchain, AnyBlockchain, CompactFilters, #[cfg(feature = "compact_filters")]);
+impl_from!(rpc::RpcBlockchain, AnyBlockchain, Rpc, #[cfg(feature = "rpc")]);
 
 /// Type that can contain any of the blockchain configurations defined by the library
 ///
@@ -188,7 +156,8 @@ impl_from!(compact_filters::CompactFiltersBlockchain, AnyBlockchain, CompactFilt
 ///     r#"{
 ///    "type" : "electrum",
 ///    "url" : "ssl://electrum.blockstream.info:50002",
-///    "retry": 2
+///    "retry": 2,
+///    "stop_gap": 20
 /// }"#,
 /// )
 /// .unwrap();
@@ -198,7 +167,8 @@ impl_from!(compact_filters::CompactFiltersBlockchain, AnyBlockchain, CompactFilt
 ///         url: "ssl://electrum.blockstream.info:50002".into(),
 ///         retry: 2,
 ///         socks5: None,
-///         timeout: None
+///         timeout: None,
+///         stop_gap: 20,
 ///     })
 /// );
 /// # }
@@ -218,6 +188,10 @@ pub enum AnyBlockchainConfig {
     #[cfg_attr(docsrs, doc(cfg(feature = "compact_filters")))]
     /// Compact filters client
     CompactFilters(compact_filters::CompactFiltersBlockchainConfig),
+    #[cfg(feature = "rpc")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "rpc")))]
+    /// RPC client configuration
+    Rpc(rpc::RpcConfig),
 }
 
 impl ConfigurableBlockchain for AnyBlockchain {
@@ -237,6 +211,10 @@ impl ConfigurableBlockchain for AnyBlockchain {
             AnyBlockchainConfig::CompactFilters(inner) => AnyBlockchain::CompactFilters(
                 compact_filters::CompactFiltersBlockchain::from_config(inner)?,
             ),
+            #[cfg(feature = "rpc")]
+            AnyBlockchainConfig::Rpc(inner) => {
+                AnyBlockchain::Rpc(rpc::RpcBlockchain::from_config(inner)?)
+            }
         })
     }
 }
@@ -244,3 +222,4 @@ impl ConfigurableBlockchain for AnyBlockchain {
 impl_from!(electrum::ElectrumBlockchainConfig, AnyBlockchainConfig, Electrum, #[cfg(feature = "electrum")]);
 impl_from!(esplora::EsploraBlockchainConfig, AnyBlockchainConfig, Esplora, #[cfg(feature = "esplora")]);
 impl_from!(compact_filters::CompactFiltersBlockchainConfig, AnyBlockchainConfig, CompactFilters, #[cfg(feature = "compact_filters")]);
+impl_from!(rpc::RpcConfig, AnyBlockchainConfig, Rpc, #[cfg(feature = "rpc")]);

src/blockchain/compact_filters/mod.rs

@@ -67,11 +67,11 @@ mod peer;
 mod store;
 mod sync;
 
-use super::{Blockchain, Capability, ConfigurableBlockchain, Progress};
+use super::{Blockchain, Capability, ConfigurableBlockchain, GetHeight, Progress, WalletSync};
 use crate::database::{BatchDatabase, BatchOperations, DatabaseUtils};
 use crate::error::Error;
 use crate::types::{KeychainKind, LocalUtxo, TransactionDetails};
-use crate::FeeRate;
+use crate::{BlockTime, FeeRate};
 
 use peer::*;
 use store::*;
@@ -146,7 +146,7 @@ impl CompactFiltersBlockchain {
         database: &mut D,
         tx: &Transaction,
         height: Option<u32>,
-        timestamp: u64,
+        timestamp: Option<u64>,
         internal_max_deriv: &mut Option<u32>,
         external_max_deriv: &mut Option<u32>,
     ) -> Result<(), Error> {
@@ -206,9 +206,9 @@ impl CompactFiltersBlockchain {
                 transaction: Some(tx.clone()),
                 received: incoming,
                 sent: outgoing,
-                height,
-                timestamp,
-                fees: inputs_sum.saturating_sub(outputs_sum),
+                confirmation_time: BlockTime::new(height, timestamp),
+                verified: height.is_some(),
+                fee: Some(inputs_sum.saturating_sub(outputs_sum)),
             };
 
             info!("Saving tx {}", tx.txid);
@@ -226,12 +226,36 @@ impl Blockchain for CompactFiltersBlockchain {
         vec![Capability::FullHistory].into_iter().collect()
     }
 
+    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
+        Ok(self.peers[0]
+            .get_mempool()
+            .get_tx(&Inventory::Transaction(*txid)))
+    }
+
+    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
+        self.peers[0].broadcast_tx(tx.clone())?;
+
+        Ok(())
+    }
+
+    fn estimate_fee(&self, _target: usize) -> Result<FeeRate, Error> {
+        // TODO
+        Ok(FeeRate::default())
+    }
+}
+
+impl GetHeight for CompactFiltersBlockchain {
+    fn get_height(&self) -> Result<u32, Error> {
+        Ok(self.headers.get_height()? as u32)
+    }
+}
+
+impl WalletSync for CompactFiltersBlockchain {
     #[allow(clippy::mutex_atomic)] // Mutex is easier to understand than a CAS loop.
-    fn setup<D: BatchDatabase, P: 'static + Progress>(
+    fn wallet_setup<D: BatchDatabase>(
         &self,
-        _stop_gap: Option<usize>, // TODO: move to electrum and esplora only
         database: &mut D,
-        progress_update: P,
+        progress_update: Box<dyn Progress>,
     ) -> Result<(), Error> {
         let first_peer = &self.peers[0];
 
@@ -255,7 +279,7 @@ impl Blockchain for CompactFiltersBlockchain {
         let total_cost = headers_cost + filters_cost + PROCESS_BLOCKS_COST;
 
         if let Some(snapshot) = sync::sync_headers(
-            Arc::clone(&first_peer),
+            Arc::clone(first_peer),
             Arc::clone(&self.headers),
             |new_height| {
                 let local_headers_cost =
@@ -276,7 +300,7 @@ impl Blockchain for CompactFiltersBlockchain {
         let buried_height = synced_height.saturating_sub(sync::BURIED_CONFIRMATIONS);
         info!("Synced headers to height: {}", synced_height);
 
-        cf_sync.prepare_sync(Arc::clone(&first_peer))?;
+        cf_sync.prepare_sync(Arc::clone(first_peer))?;
 
         let all_scripts = Arc::new(
             database
@@ -295,7 +319,7 @@ impl Blockchain for CompactFiltersBlockchain {
         let mut threads = Vec::with_capacity(self.peers.len());
         for peer in &self.peers {
             let cf_sync = Arc::clone(&cf_sync);
-            let peer = Arc::clone(&peer);
+            let peer = Arc::clone(peer);
             let headers = Arc::clone(&self.headers);
             let all_scripts = Arc::clone(&all_scripts);
             let last_synced_block = Arc::clone(&last_synced_block);
@@ -364,8 +388,8 @@ impl Blockchain for CompactFiltersBlockchain {
         );
         let mut updates = database.begin_batch();
         for details in database.iter_txs(false)? {
-            match details.height {
-                Some(height) if (height as usize) < last_synced_block => continue,
+            match details.confirmation_time {
+                Some(c) if (c.height as usize) < last_synced_block => continue,
                 _ => updates.del_tx(&details.txid, false)?,
             };
         }
@@ -387,7 +411,7 @@ impl Blockchain for CompactFiltersBlockchain {
                     database,
                     tx,
                     Some(height as u32),
-                    0,
+                    None,
                     &mut internal_max_deriv,
                     &mut external_max_deriv,
                 )?;
@@ -398,7 +422,7 @@ impl Blockchain for CompactFiltersBlockchain {
                 database,
                 tx,
                 None,
-                0,
+                None,
                 &mut internal_max_deriv,
                 &mut external_max_deriv,
             )?;
@@ -432,27 +456,6 @@ impl Blockchain for CompactFiltersBlockchain {
 
         Ok(())
     }
-
-    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
-        Ok(self.peers[0]
-            .get_mempool()
-            .get_tx(&Inventory::Transaction(*txid)))
-    }
-
-    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
-        self.peers[0].broadcast_tx(tx.clone())?;
-
-        Ok(())
-    }
-
-    fn get_height(&self) -> Result<u32, Error> {
-        Ok(self.headers.get_height()? as u32)
-    }
-
-    fn estimate_fee(&self, _target: usize) -> Result<FeeRate, Error> {
-        // TODO
-        Ok(FeeRate::default())
-    }
 }
 
 /// Data to connect to a Bitcoin P2P peer
@@ -473,7 +476,7 @@ pub struct CompactFiltersBlockchainConfig {
     pub peers: Vec<BitcoinPeerConfig>,
     /// Network used
     pub network: Network,
-    /// Storage dir to save partially downloaded headers and full blocks
+    /// Storage dir to save partially downloaded headers and full blocks. Should be a separate directory per descriptor. Consider using [crate::wallet::wallet_name_from_descriptor] for this.
     pub storage_dir: String,
     /// Optionally skip initial `skip_blocks` blocks (default: 0)
     pub skip_blocks: Option<usize>,

src/blockchain/compact_filters/peer.rs

@@ -227,12 +227,12 @@ impl Peer {
 
         Ok(Peer {
             writer,
-            reader_thread,
             responses,
+            reader_thread,
             connected,
             mempool,
-            network,
             version,
+            network,
         })
     }
 
@@ -262,7 +262,7 @@ impl Peer {
         let message_resp = {
             let mut lock = responses.write().unwrap();
             let message_resp = lock.entry(wait_for).or_default();
-            Arc::clone(&message_resp)
+            Arc::clone(message_resp)
         };
 
         let (lock, cvar) = &*message_resp;
@@ -379,7 +379,7 @@ impl Peer {
             let message_resp = {
                 let mut lock = reader_thread_responses.write().unwrap();
                 let message_resp = lock.entry(in_message.cmd()).or_default();
-                Arc::clone(&message_resp)
+                Arc::clone(message_resp)
             };
 
             let (lock, cvar) = &*message_resp;

src/blockchain/compact_filters/store.rs

@@ -398,7 +398,7 @@ impl ChainStore<Full> {
             );
         }
 
-        // Delete full blocks overriden by snapshot
+        // Delete full blocks overridden by snapshot
         let from_key = StoreEntry::Block(Some(snaphost.min_height)).get_key();
         let to_key = StoreEntry::Block(Some(usize::MAX)).get_key();
         batch.delete_range(&from_key, &to_key);
@@ -760,7 +760,7 @@ impl CfStore {
         let cf_headers: Vec<FilterHeader> = filter_hashes
             .into_iter()
             .scan(checkpoint, |prev_header, filter_hash| {
-                let filter_header = filter_hash.filter_header(&prev_header);
+                let filter_header = filter_hash.filter_header(prev_header);
                 *prev_header = filter_header;
 
                 Some(filter_header)
@@ -801,7 +801,7 @@ impl CfStore {
             .zip(headers.into_iter())
             .scan(checkpoint, |prev_header, ((_, filter_content), header)| {
                 let filter = BlockFilter::new(&filter_content);
-                if header != filter.filter_header(&prev_header) {
+                if header != filter.filter_header(prev_header) {
                     return Some(Err(CompactFiltersError::InvalidFilter));
                 }
                 *prev_header = header;

src/blockchain/compact_filters/sync.rs

@@ -205,7 +205,7 @@ impl CfSync {
                     let block_hash = self.headers_store.get_block_hash(height)?.unwrap();
 
                     // TODO: also download random blocks?
-                    if process(&block_hash, &BlockFilter::new(&filter))? {
+                    if process(&block_hash, &BlockFilter::new(filter))? {
                         log::debug!("Downloading block {}", block_hash);
 
                         let block = peer

src/blockchain/electrum.rs

@@ -24,30 +24,36 @@
 //! # Ok::<(), bdk::Error>(())
 //! ```
 
-use std::collections::HashSet;
+use std::collections::{HashMap, HashSet};
 
 #[allow(unused_imports)]
 use log::{debug, error, info, trace};
 
-use bitcoin::{BlockHeader, Script, Transaction, Txid};
+use bitcoin::{Transaction, Txid};
 
 use electrum_client::{Client, ConfigBuilder, ElectrumApi, Socks5Config};
 
-use self::utils::{ElectrumLikeSync, ElsGetHistoryRes};
+use super::script_sync::Request;
 use super::*;
-use crate::database::BatchDatabase;
+use crate::database::{BatchDatabase, Database};
 use crate::error::Error;
-use crate::FeeRate;
+use crate::{BlockTime, FeeRate};
 
 /// Wrapper over an Electrum Client that implements the required blockchain traits
 ///
 /// ## Example
 /// See the [`blockchain::electrum`](crate::blockchain::electrum) module for a usage example.
-pub struct ElectrumBlockchain(Client);
+pub struct ElectrumBlockchain {
+    client: Client,
+    stop_gap: usize,
+}
 
 impl std::convert::From<Client> for ElectrumBlockchain {
     fn from(client: Client) -> Self {
-        ElectrumBlockchain(client)
+        ElectrumBlockchain {
+            client,
+            stop_gap: 20,
+        }
     }
 }
 
@@ -62,77 +68,214 @@ impl Blockchain for ElectrumBlockchain {
         .collect()
     }
 
-    fn setup<D: BatchDatabase, P: Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error> {
-        self.0
-            .electrum_like_setup(stop_gap, database, progress_update)
-    }
-
     fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
-        Ok(self.0.transaction_get(txid).map(Option::Some)?)
+        Ok(self.client.transaction_get(txid).map(Option::Some)?)
     }
 
     fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
-        Ok(self.0.transaction_broadcast(tx).map(|_| ())?)
-    }
-
-    fn get_height(&self) -> Result<u32, Error> {
-        // TODO: unsubscribe when added to the client, or is there a better call to use here?
-
-        Ok(self
-            .0
-            .block_headers_subscribe()
-            .map(|data| data.height as u32)?)
+        Ok(self.client.transaction_broadcast(tx).map(|_| ())?)
     }
 
     fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
         Ok(FeeRate::from_btc_per_kvb(
-            self.0.estimate_fee(target)? as f32
+            self.client.estimate_fee(target)? as f32
         ))
     }
 }
 
-impl ElectrumLikeSync for Client {
-    fn els_batch_script_get_history<'s, I: IntoIterator<Item = &'s Script> + Clone>(
+impl GetHeight for ElectrumBlockchain {
+    fn get_height(&self) -> Result<u32, Error> {
+        // TODO: unsubscribe when added to the client, or is there a better call to use here?
+
+        Ok(self
+            .client
+            .block_headers_subscribe()
+            .map(|data| data.height as u32)?)
+    }
+}
+
+impl WalletSync for ElectrumBlockchain {
+    fn wallet_setup<D: BatchDatabase>(
         &self,
-        scripts: I,
-    ) -> Result<Vec<Vec<ElsGetHistoryRes>>, Error> {
-        self.batch_script_get_history(scripts)
-            .map(|v| {
-                v.into_iter()
-                    .map(|v| {
-                        v.into_iter()
-                            .map(
-                                |electrum_client::GetHistoryRes {
-                                     height, tx_hash, ..
-                                 }| ElsGetHistoryRes {
-                                    height,
-                                    tx_hash,
-                                },
-                            )
-                            .collect()
-                    })
-                    .collect()
-            })
-            .map_err(Error::Electrum)
+        database: &mut D,
+        _progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        let mut request = script_sync::start(database, self.stop_gap)?;
+        let mut block_times = HashMap::<u32, u32>::new();
+        let mut txid_to_height = HashMap::<Txid, u32>::new();
+        let mut tx_cache = TxCache::new(database, &self.client);
+        let chunk_size = self.stop_gap;
+        // The electrum server has been inconsistent somehow in its responses during sync. For
+        // example, we do a batch request of transactions and the response contains less
+        // tranascations than in the request. This should never happen but we don't want to panic.
+        let electrum_goof = || Error::Generic("electrum server misbehaving".to_string());
+
+        let batch_update = loop {
+            request = match request {
+                Request::Script(script_req) => {
+                    let scripts = script_req.request().take(chunk_size);
+                    let txids_per_script: Vec<Vec<_>> = self
+                        .client
+                        .batch_script_get_history(scripts)
+                        .map_err(Error::Electrum)?
+                        .into_iter()
+                        .map(|txs| {
+                            txs.into_iter()
+                                .map(|tx| {
+                                    let tx_height = match tx.height {
+                                        none if none <= 0 => None,
+                                        height => {
+                                            txid_to_height.insert(tx.tx_hash, height as u32);
+                                            Some(height as u32)
+                                        }
+                                    };
+                                    (tx.tx_hash, tx_height)
+                                })
+                                .collect()
+                        })
+                        .collect();
+
+                    script_req.satisfy(txids_per_script)?
+                }
+
+                Request::Conftime(conftime_req) => {
+                    // collect up to chunk_size heights to fetch from electrum
+                    let needs_block_height = {
+                        let mut needs_block_height_iter = conftime_req
+                            .request()
+                            .filter_map(|txid| txid_to_height.get(txid).cloned())
+                            .filter(|height| block_times.get(height).is_none());
+                        let mut needs_block_height = HashSet::new();
+
+                        while needs_block_height.len() < chunk_size {
+                            match needs_block_height_iter.next() {
+                                Some(height) => needs_block_height.insert(height),
+                                None => break,
+                            };
+                        }
+                        needs_block_height
+                    };
+
+                    let new_block_headers = self
+                        .client
+                        .batch_block_header(needs_block_height.iter().cloned())?;
+
+                    for (height, header) in needs_block_height.into_iter().zip(new_block_headers) {
+                        block_times.insert(height, header.time);
+                    }
+
+                    let conftimes = conftime_req
+                        .request()
+                        .take(chunk_size)
+                        .map(|txid| {
+                            let confirmation_time = txid_to_height
+                                .get(txid)
+                                .map(|height| {
+                                    let timestamp =
+                                        *block_times.get(height).ok_or_else(electrum_goof)?;
+                                    Result::<_, Error>::Ok(BlockTime {
+                                        height: *height,
+                                        timestamp: timestamp.into(),
+                                    })
+                                })
+                                .transpose()?;
+                            Ok(confirmation_time)
+                        })
+                        .collect::<Result<_, Error>>()?;
+
+                    conftime_req.satisfy(conftimes)?
+                }
+                Request::Tx(tx_req) => {
+                    let needs_full = tx_req.request().take(chunk_size);
+                    tx_cache.save_txs(needs_full.clone())?;
+                    let full_transactions = needs_full
+                        .map(|txid| tx_cache.get(*txid).ok_or_else(electrum_goof))
+                        .collect::<Result<Vec<_>, _>>()?;
+                    let input_txs = full_transactions.iter().flat_map(|tx| {
+                        tx.input
+                            .iter()
+                            .filter(|input| !input.previous_output.is_null())
+                            .map(|input| &input.previous_output.txid)
+                    });
+                    tx_cache.save_txs(input_txs)?;
+
+                    let full_details = full_transactions
+                        .into_iter()
+                        .map(|tx| {
+                            let prev_outputs = tx
+                                .input
+                                .iter()
+                                .map(|input| {
+                                    if input.previous_output.is_null() {
+                                        return Ok(None);
+                                    }
+                                    let prev_tx = tx_cache
+                                        .get(input.previous_output.txid)
+                                        .ok_or_else(electrum_goof)?;
+                                    let txout = prev_tx
+                                        .output
+                                        .get(input.previous_output.vout as usize)
+                                        .ok_or_else(electrum_goof)?;
+                                    Ok(Some(txout.clone()))
+                                })
+                                .collect::<Result<Vec<_>, Error>>()?;
+                            Ok((prev_outputs, tx))
+                        })
+                        .collect::<Result<Vec<_>, Error>>()?;
+
+                    tx_req.satisfy(full_details)?
+                }
+                Request::Finish(batch_update) => break batch_update,
+            }
+        };
+
+        database.commit_batch(batch_update)?;
+        Ok(())
+    }
+}
+
+struct TxCache<'a, 'b, D> {
+    db: &'a D,
+    client: &'b Client,
+    cache: HashMap<Txid, Transaction>,
+}
+
+impl<'a, 'b, D: Database> TxCache<'a, 'b, D> {
+    fn new(db: &'a D, client: &'b Client) -> Self {
+        TxCache {
+            db,
+            client,
+            cache: HashMap::default(),
+        }
+    }
+    fn save_txs<'c>(&mut self, txids: impl Iterator<Item = &'c Txid>) -> Result<(), Error> {
+        let mut need_fetch = vec![];
+        for txid in txids {
+            if self.cache.get(txid).is_some() {
+                continue;
+            } else if let Some(transaction) = self.db.get_raw_tx(txid)? {
+                self.cache.insert(*txid, transaction);
+            } else {
+                need_fetch.push(txid);
+            }
+        }
+
+        if !need_fetch.is_empty() {
+            let txs = self
+                .client
+                .batch_transaction_get(need_fetch.clone())
+                .map_err(Error::Electrum)?;
+            for (tx, _txid) in txs.into_iter().zip(need_fetch) {
+                debug_assert_eq!(*_txid, tx.txid());
+                self.cache.insert(tx.txid(), tx);
+            }
+        }
+
+        Ok(())
     }
 
-    fn els_batch_transaction_get<'s, I: IntoIterator<Item = &'s Txid> + Clone>(
-        &self,
-        txids: I,
-    ) -> Result<Vec<Transaction>, Error> {
-        self.batch_transaction_get(txids).map_err(Error::Electrum)
-    }
-
-    fn els_batch_block_header<I: IntoIterator<Item = u32> + Clone>(
-        &self,
-        heights: I,
-    ) -> Result<Vec<BlockHeader>, Error> {
-        self.batch_block_header(heights).map_err(Error::Electrum)
+    fn get(&self, txid: Txid) -> Option<Transaction> {
+        self.cache.get(&txid).map(Clone::clone)
     }
 }
 
@@ -149,6 +292,8 @@ pub struct ElectrumBlockchainConfig {
     pub retry: u8,
     /// Request timeout (seconds)
     pub timeout: Option<u8>,
+    /// Stop searching addresses for transactions after finding an unused gap of this length
+    pub stop_gap: usize,
 }
 
 impl ConfigurableBlockchain for ElectrumBlockchain {
@@ -162,16 +307,17 @@ impl ConfigurableBlockchain for ElectrumBlockchain {
             .socks5(socks5)?
             .build();
 
-        Ok(ElectrumBlockchain(Client::from_config(
-            config.url.as_str(),
-            electrum_config,
-        )?))
+        Ok(ElectrumBlockchain {
+            client: Client::from_config(config.url.as_str(), electrum_config)?,
+            stop_gap: config.stop_gap,
+        })
     }
 }
 
-#[cfg(feature = "test-blockchains")]
+#[cfg(test)]
+#[cfg(feature = "test-electrum")]
 crate::bdk_blockchain_tests! {
-    fn test_instance() -> ElectrumBlockchain {
-        ElectrumBlockchain::from(Client::new(&testutils::blockchain_tests::get_electrum_url()).unwrap())
+    fn test_instance(test_client: &TestClient) -> ElectrumBlockchain {
+        ElectrumBlockchain::from(Client::new(&test_client.electrsd.electrum_url).unwrap())
     }
 }

src/blockchain/esplora.rs

@@ -1,423 +0,0 @@
-// Bitcoin Dev Kit
-// Written in 2020 by Alekos Filini <alekos.filini@gmail.com>
-//
-// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
-//
-// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
-// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
-// You may not use this file except in accordance with one or both of these
-// licenses.
-
-//! Esplora
-//!
-//! This module defines a [`Blockchain`] struct that can query an Esplora backend
-//! populate the wallet's [database](crate::database::Database) by
-//!
-//! ## Example
-//!
-//! ```no_run
-//! # use bdk::blockchain::esplora::EsploraBlockchain;
-//! let blockchain = EsploraBlockchain::new("https://blockstream.info/testnet/api", None);
-//! # Ok::<(), bdk::Error>(())
-//! ```
-
-use std::collections::{HashMap, HashSet};
-use std::fmt;
-
-use futures::stream::{self, FuturesOrdered, StreamExt, TryStreamExt};
-
-#[allow(unused_imports)]
-use log::{debug, error, info, trace};
-
-use serde::Deserialize;
-
-use reqwest::{Client, StatusCode};
-
-use bitcoin::consensus::{self, deserialize, serialize};
-use bitcoin::hashes::hex::{FromHex, ToHex};
-use bitcoin::hashes::{sha256, Hash};
-use bitcoin::{BlockHash, BlockHeader, Script, Transaction, Txid};
-
-use self::utils::{ElectrumLikeSync, ElsGetHistoryRes};
-use super::*;
-use crate::database::BatchDatabase;
-use crate::error::Error;
-use crate::wallet::utils::ChunksIterator;
-use crate::FeeRate;
-
-const DEFAULT_CONCURRENT_REQUESTS: u8 = 4;
-
-#[derive(Debug)]
-struct UrlClient {
-    url: String,
-    // We use the async client instead of the blocking one because it automatically uses `fetch`
-    // when the target platform is wasm32.
-    client: Client,
-    concurrency: u8,
-}
-
-/// Structure that implements the logic to sync with Esplora
-///
-/// ## Example
-/// See the [`blockchain::esplora`](crate::blockchain::esplora) module for a usage example.
-#[derive(Debug)]
-pub struct EsploraBlockchain(UrlClient);
-
-impl std::convert::From<UrlClient> for EsploraBlockchain {
-    fn from(url_client: UrlClient) -> Self {
-        EsploraBlockchain(url_client)
-    }
-}
-
-impl EsploraBlockchain {
-    /// Create a new instance of the client from a base URL
-    pub fn new(base_url: &str, concurrency: Option<u8>) -> Self {
-        EsploraBlockchain(UrlClient {
-            url: base_url.to_string(),
-            client: Client::new(),
-            concurrency: concurrency.unwrap_or(DEFAULT_CONCURRENT_REQUESTS),
-        })
-    }
-}
-
-#[maybe_async]
-impl Blockchain for EsploraBlockchain {
-    fn get_capabilities(&self) -> HashSet<Capability> {
-        vec![
-            Capability::FullHistory,
-            Capability::GetAnyTx,
-            Capability::AccurateFees,
-        ]
-        .into_iter()
-        .collect()
-    }
-
-    fn setup<D: BatchDatabase, P: Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error> {
-        maybe_await!(self
-            .0
-            .electrum_like_setup(stop_gap, database, progress_update))
-    }
-
-    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
-        Ok(await_or_block!(self.0._get_tx(txid))?)
-    }
-
-    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
-        Ok(await_or_block!(self.0._broadcast(tx))?)
-    }
-
-    fn get_height(&self) -> Result<u32, Error> {
-        Ok(await_or_block!(self.0._get_height())?)
-    }
-
-    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
-        let estimates = await_or_block!(self.0._get_fee_estimates())?;
-
-        let fee_val = estimates
-            .into_iter()
-            .map(|(k, v)| Ok::<_, std::num::ParseIntError>((k.parse::<usize>()?, v)))
-            .collect::<Result<Vec<_>, _>>()
-            .map_err(|e| Error::Generic(e.to_string()))?
-            .into_iter()
-            .take_while(|(k, _)| k <= &target)
-            .map(|(_, v)| v)
-            .last()
-            .unwrap_or(1.0);
-
-        Ok(FeeRate::from_sat_per_vb(fee_val as f32))
-    }
-}
-
-impl UrlClient {
-    fn script_to_scripthash(script: &Script) -> String {
-        sha256::Hash::hash(script.as_bytes()).into_inner().to_hex()
-    }
-
-    async fn _get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, EsploraError> {
-        let resp = self
-            .client
-            .get(&format!("{}/tx/{}/raw", self.url, txid))
-            .send()
-            .await?;
-
-        if let StatusCode::NOT_FOUND = resp.status() {
-            return Ok(None);
-        }
-
-        Ok(Some(deserialize(&resp.error_for_status()?.bytes().await?)?))
-    }
-
-    async fn _get_tx_no_opt(&self, txid: &Txid) -> Result<Transaction, EsploraError> {
-        match self._get_tx(txid).await {
-            Ok(Some(tx)) => Ok(tx),
-            Ok(None) => Err(EsploraError::TransactionNotFound(*txid)),
-            Err(e) => Err(e),
-        }
-    }
-
-    async fn _get_header(&self, block_height: u32) -> Result<BlockHeader, EsploraError> {
-        let resp = self
-            .client
-            .get(&format!("{}/block-height/{}", self.url, block_height))
-            .send()
-            .await?;
-
-        if let StatusCode::NOT_FOUND = resp.status() {
-            return Err(EsploraError::HeaderHeightNotFound(block_height));
-        }
-        let bytes = resp.bytes().await?;
-        let hash = std::str::from_utf8(&bytes)
-            .map_err(|_| EsploraError::HeaderHeightNotFound(block_height))?;
-
-        let resp = self
-            .client
-            .get(&format!("{}/block/{}/header", self.url, hash))
-            .send()
-            .await?;
-
-        let header = deserialize(&Vec::from_hex(&resp.text().await?)?)?;
-
-        Ok(header)
-    }
-
-    async fn _broadcast(&self, transaction: &Transaction) -> Result<(), EsploraError> {
-        self.client
-            .post(&format!("{}/tx", self.url))
-            .body(serialize(transaction).to_hex())
-            .send()
-            .await?
-            .error_for_status()?;
-
-        Ok(())
-    }
-
-    async fn _get_height(&self) -> Result<u32, EsploraError> {
-        let req = self
-            .client
-            .get(&format!("{}/blocks/tip/height", self.url))
-            .send()
-            .await?;
-
-        Ok(req.error_for_status()?.text().await?.parse()?)
-    }
-
-    async fn _script_get_history(
-        &self,
-        script: &Script,
-    ) -> Result<Vec<ElsGetHistoryRes>, EsploraError> {
-        let mut result = Vec::new();
-        let scripthash = Self::script_to_scripthash(script);
-
-        // Add the unconfirmed transactions first
-        result.extend(
-            self.client
-                .get(&format!(
-                    "{}/scripthash/{}/txs/mempool",
-                    self.url, scripthash
-                ))
-                .send()
-                .await?
-                .error_for_status()?
-                .json::<Vec<EsploraGetHistory>>()
-                .await?
-                .into_iter()
-                .map(|x| ElsGetHistoryRes {
-                    tx_hash: x.txid,
-                    height: x.status.block_height.unwrap_or(0) as i32,
-                }),
-        );
-
-        debug!(
-            "Found {} mempool txs for {} - {:?}",
-            result.len(),
-            scripthash,
-            script
-        );
-
-        // Then go through all the pages of confirmed transactions
-        let mut last_txid = String::new();
-        loop {
-            let response = self
-                .client
-                .get(&format!(
-                    "{}/scripthash/{}/txs/chain/{}",
-                    self.url, scripthash, last_txid
-                ))
-                .send()
-                .await?
-                .error_for_status()?
-                .json::<Vec<EsploraGetHistory>>()
-                .await?;
-            let len = response.len();
-            if let Some(elem) = response.last() {
-                last_txid = elem.txid.to_hex();
-            }
-
-            debug!("... adding {} confirmed transactions", len);
-
-            result.extend(response.into_iter().map(|x| ElsGetHistoryRes {
-                tx_hash: x.txid,
-                height: x.status.block_height.unwrap_or(0) as i32,
-            }));
-
-            if len < 25 {
-                break;
-            }
-        }
-
-        Ok(result)
-    }
-
-    async fn _get_fee_estimates(&self) -> Result<HashMap<String, f64>, EsploraError> {
-        Ok(self
-            .client
-            .get(&format!("{}/fee-estimates", self.url,))
-            .send()
-            .await?
-            .error_for_status()?
-            .json::<HashMap<String, f64>>()
-            .await?)
-    }
-}
-
-#[maybe_async]
-impl ElectrumLikeSync for UrlClient {
-    fn els_batch_script_get_history<'s, I: IntoIterator<Item = &'s Script>>(
-        &self,
-        scripts: I,
-    ) -> Result<Vec<Vec<ElsGetHistoryRes>>, Error> {
-        let future = async {
-            let mut results = vec![];
-            for chunk in ChunksIterator::new(scripts.into_iter(), self.concurrency as usize) {
-                let mut futs = FuturesOrdered::new();
-                for script in chunk {
-                    futs.push(self._script_get_history(&script));
-                }
-                let partial_results: Vec<Vec<ElsGetHistoryRes>> = futs.try_collect().await?;
-                results.extend(partial_results);
-            }
-            Ok(stream::iter(results).collect().await)
-        };
-
-        await_or_block!(future)
-    }
-
-    fn els_batch_transaction_get<'s, I: IntoIterator<Item = &'s Txid>>(
-        &self,
-        txids: I,
-    ) -> Result<Vec<Transaction>, Error> {
-        let future = async {
-            let mut results = vec![];
-            for chunk in ChunksIterator::new(txids.into_iter(), self.concurrency as usize) {
-                let mut futs = FuturesOrdered::new();
-                for txid in chunk {
-                    futs.push(self._get_tx_no_opt(&txid));
-                }
-                let partial_results: Vec<Transaction> = futs.try_collect().await?;
-                results.extend(partial_results);
-            }
-            Ok(stream::iter(results).collect().await)
-        };
-
-        await_or_block!(future)
-    }
-
-    fn els_batch_block_header<I: IntoIterator<Item = u32>>(
-        &self,
-        heights: I,
-    ) -> Result<Vec<BlockHeader>, Error> {
-        let future = async {
-            let mut results = vec![];
-            for chunk in ChunksIterator::new(heights.into_iter(), self.concurrency as usize) {
-                let mut futs = FuturesOrdered::new();
-                for height in chunk {
-                    futs.push(self._get_header(height));
-                }
-                let partial_results: Vec<BlockHeader> = futs.try_collect().await?;
-                results.extend(partial_results);
-            }
-            Ok(stream::iter(results).collect().await)
-        };
-
-        await_or_block!(future)
-    }
-}
-
-#[derive(Deserialize)]
-struct EsploraGetHistoryStatus {
-    block_height: Option<usize>,
-}
-
-#[derive(Deserialize)]
-struct EsploraGetHistory {
-    txid: Txid,
-    status: EsploraGetHistoryStatus,
-}
-
-/// Configuration for an [`EsploraBlockchain`]
-#[derive(Debug, serde::Deserialize, serde::Serialize, Clone, PartialEq)]
-pub struct EsploraBlockchainConfig {
-    /// Base URL of the esplora service
-    ///
-    /// eg. `https://blockstream.info/api/`
-    pub base_url: String,
-    /// Number of parallel requests sent to the esplora service (default: 4)
-    pub concurrency: Option<u8>,
-}
-
-impl ConfigurableBlockchain for EsploraBlockchain {
-    type Config = EsploraBlockchainConfig;
-
-    fn from_config(config: &Self::Config) -> Result<Self, Error> {
-        Ok(EsploraBlockchain::new(
-            config.base_url.as_str(),
-            config.concurrency,
-        ))
-    }
-}
-
-/// Errors that can happen during a sync with [`EsploraBlockchain`]
-#[derive(Debug)]
-pub enum EsploraError {
-    /// Error with the HTTP call
-    Reqwest(reqwest::Error),
-    /// Invalid number returned
-    Parsing(std::num::ParseIntError),
-    /// Invalid Bitcoin data returned
-    BitcoinEncoding(bitcoin::consensus::encode::Error),
-    /// Invalid Hex data returned
-    Hex(bitcoin::hashes::hex::Error),
-
-    /// Transaction not found
-    TransactionNotFound(Txid),
-    /// Header height not found
-    HeaderHeightNotFound(u32),
-    /// Header hash not found
-    HeaderHashNotFound(BlockHash),
-}
-
-impl fmt::Display for EsploraError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:?}", self)
-    }
-}
-
-impl std::error::Error for EsploraError {}
-
-impl_error!(reqwest::Error, Reqwest, EsploraError);
-impl_error!(std::num::ParseIntError, Parsing, EsploraError);
-impl_error!(consensus::encode::Error, BitcoinEncoding, EsploraError);
-impl_error!(bitcoin::hashes::hex::Error, Hex, EsploraError);
-
-#[cfg(feature = "test-blockchains")]
-crate::bdk_blockchain_tests! {
-    fn test_instance() -> EsploraBlockchain {
-        EsploraBlockchain::new(std::env::var("BDK_ESPLORA_URL").unwrap_or("127.0.0.1:3002".into()).as_str(), None)
-    }
-}

src/blockchain/esplora/api.rs

@@ -0,0 +1,117 @@
+//! structs from the esplora API
+//!
+//! see: <https://github.com/Blockstream/esplora/blob/master/API.md>
+use crate::BlockTime;
+use bitcoin::{OutPoint, Script, Transaction, TxIn, TxOut, Txid};
+
+#[derive(serde::Deserialize, Clone, Debug)]
+pub struct PrevOut {
+    pub value: u64,
+    pub scriptpubkey: Script,
+}
+
+#[derive(serde::Deserialize, Clone, Debug)]
+pub struct Vin {
+    pub txid: Txid,
+    pub vout: u32,
+    // None if coinbase
+    pub prevout: Option<PrevOut>,
+    pub scriptsig: Script,
+    #[serde(deserialize_with = "deserialize_witness")]
+    pub witness: Vec<Vec<u8>>,
+    pub sequence: u32,
+    pub is_coinbase: bool,
+}
+
+#[derive(serde::Deserialize, Clone, Debug)]
+pub struct Vout {
+    pub value: u64,
+    pub scriptpubkey: Script,
+}
+
+#[derive(serde::Deserialize, Clone, Debug)]
+pub struct TxStatus {
+    pub confirmed: bool,
+    pub block_height: Option<u32>,
+    pub block_time: Option<u64>,
+}
+
+#[derive(serde::Deserialize, Clone, Debug)]
+pub struct Tx {
+    pub txid: Txid,
+    pub version: i32,
+    pub locktime: u32,
+    pub vin: Vec<Vin>,
+    pub vout: Vec<Vout>,
+    pub status: TxStatus,
+    pub fee: u64,
+}
+
+impl Tx {
+    pub fn to_tx(&self) -> Transaction {
+        Transaction {
+            version: self.version,
+            lock_time: self.locktime,
+            input: self
+                .vin
+                .iter()
+                .cloned()
+                .map(|vin| TxIn {
+                    previous_output: OutPoint {
+                        txid: vin.txid,
+                        vout: vin.vout,
+                    },
+                    script_sig: vin.scriptsig,
+                    sequence: vin.sequence,
+                    witness: vin.witness,
+                })
+                .collect(),
+            output: self
+                .vout
+                .iter()
+                .cloned()
+                .map(|vout| TxOut {
+                    value: vout.value,
+                    script_pubkey: vout.scriptpubkey,
+                })
+                .collect(),
+        }
+    }
+
+    pub fn confirmation_time(&self) -> Option<BlockTime> {
+        match self.status {
+            TxStatus {
+                confirmed: true,
+                block_height: Some(height),
+                block_time: Some(timestamp),
+            } => Some(BlockTime { timestamp, height }),
+            _ => None,
+        }
+    }
+
+    pub fn previous_outputs(&self) -> Vec<Option<TxOut>> {
+        self.vin
+            .iter()
+            .cloned()
+            .map(|vin| {
+                vin.prevout.map(|po| TxOut {
+                    script_pubkey: po.scriptpubkey,
+                    value: po.value,
+                })
+            })
+            .collect()
+    }
+}
+
+fn deserialize_witness<'de, D>(d: D) -> Result<Vec<Vec<u8>>, D::Error>
+where
+    D: serde::de::Deserializer<'de>,
+{
+    use crate::serde::Deserialize;
+    use bitcoin::hashes::hex::FromHex;
+    let list = Vec::<String>::deserialize(d)?;
+    list.into_iter()
+        .map(|hex_str| Vec::<u8>::from_hex(&hex_str))
+        .collect::<Result<Vec<Vec<u8>>, _>>()
+        .map_err(serde::de::Error::custom)
+}

src/blockchain/esplora/mod.rs

@@ -0,0 +1,212 @@
+//! Esplora
+//!
+//! This module defines a [`EsploraBlockchain`] struct that can query an Esplora
+//! backend populate the wallet's [database](crate::database::Database) by:
+//!
+//! ## Example
+//!
+//! ```no_run
+//! # use bdk::blockchain::esplora::EsploraBlockchain;
+//! let blockchain = EsploraBlockchain::new("https://blockstream.info/testnet/api", 20);
+//! # Ok::<(), bdk::Error>(())
+//! ```
+//!
+//! Esplora blockchain can use either `ureq` or `reqwest` for the HTTP client
+//! depending on your needs (blocking or async respectively).
+//!
+//! Please note, to configure the Esplora HTTP client correctly use one of:
+//! Blocking:  --features='esplora,ureq'
+//! Async:     --features='async-interface,esplora,reqwest' --no-default-features
+use std::collections::HashMap;
+use std::fmt;
+use std::io;
+
+use bitcoin::consensus;
+use bitcoin::{BlockHash, Txid};
+
+use crate::error::Error;
+use crate::FeeRate;
+
+#[cfg(feature = "reqwest")]
+mod reqwest;
+
+#[cfg(feature = "reqwest")]
+pub use self::reqwest::*;
+
+#[cfg(feature = "ureq")]
+mod ureq;
+
+#[cfg(feature = "ureq")]
+pub use self::ureq::*;
+
+mod api;
+
+fn into_fee_rate(target: usize, estimates: HashMap<String, f64>) -> Result<FeeRate, Error> {
+    let fee_val = {
+        let mut pairs = estimates
+            .into_iter()
+            .filter_map(|(k, v)| Some((k.parse::<usize>().ok()?, v)))
+            .collect::<Vec<_>>();
+        pairs.sort_unstable_by_key(|(k, _)| std::cmp::Reverse(*k));
+        pairs
+            .into_iter()
+            .find(|(k, _)| k <= &target)
+            .map(|(_, v)| v)
+            .unwrap_or(1.0)
+    };
+    Ok(FeeRate::from_sat_per_vb(fee_val as f32))
+}
+
+/// Errors that can happen during a sync with [`EsploraBlockchain`]
+#[derive(Debug)]
+pub enum EsploraError {
+    /// Error during ureq HTTP request
+    #[cfg(feature = "ureq")]
+    Ureq(::ureq::Error),
+    /// Transport error during the ureq HTTP call
+    #[cfg(feature = "ureq")]
+    UreqTransport(::ureq::Transport),
+    /// Error during reqwest HTTP request
+    #[cfg(feature = "reqwest")]
+    Reqwest(::reqwest::Error),
+    /// HTTP response error
+    HttpResponse(u16),
+    /// IO error during ureq response read
+    Io(io::Error),
+    /// No header found in ureq response
+    NoHeader,
+    /// Invalid number returned
+    Parsing(std::num::ParseIntError),
+    /// Invalid Bitcoin data returned
+    BitcoinEncoding(bitcoin::consensus::encode::Error),
+    /// Invalid Hex data returned
+    Hex(bitcoin::hashes::hex::Error),
+
+    /// Transaction not found
+    TransactionNotFound(Txid),
+    /// Header height not found
+    HeaderHeightNotFound(u32),
+    /// Header hash not found
+    HeaderHashNotFound(BlockHash),
+}
+
+impl fmt::Display for EsploraError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+/// Configuration for an [`EsploraBlockchain`]
+#[derive(Debug, serde::Deserialize, serde::Serialize, Clone, PartialEq)]
+pub struct EsploraBlockchainConfig {
+    /// Base URL of the esplora service
+    ///
+    /// eg. `https://blockstream.info/api/`
+    pub base_url: String,
+    /// Optional URL of the proxy to use to make requests to the Esplora server
+    ///
+    /// The string should be formatted as: `<protocol>://<user>:<password>@host:<port>`.
+    ///
+    /// Note that the format of this value and the supported protocols change slightly between the
+    /// sync version of esplora (using `ureq`) and the async version (using `reqwest`). For more
+    /// details check with the documentation of the two crates. Both of them are compiled with
+    /// the `socks` feature enabled.
+    ///
+    /// The proxy is ignored when targeting `wasm32`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub proxy: Option<String>,
+    /// Number of parallel requests sent to the esplora service (default: 4)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub concurrency: Option<u8>,
+    /// Stop searching addresses for transactions after finding an unused gap of this length.
+    pub stop_gap: usize,
+    /// Socket timeout.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub timeout: Option<u64>,
+}
+
+impl EsploraBlockchainConfig {
+    /// create a config with default values given the base url and stop gap
+    pub fn new(base_url: String, stop_gap: usize) -> Self {
+        Self {
+            base_url,
+            proxy: None,
+            timeout: None,
+            stop_gap,
+            concurrency: None,
+        }
+    }
+}
+
+impl std::error::Error for EsploraError {}
+
+#[cfg(feature = "ureq")]
+impl_error!(::ureq::Transport, UreqTransport, EsploraError);
+#[cfg(feature = "reqwest")]
+impl_error!(::reqwest::Error, Reqwest, EsploraError);
+impl_error!(io::Error, Io, EsploraError);
+impl_error!(std::num::ParseIntError, Parsing, EsploraError);
+impl_error!(consensus::encode::Error, BitcoinEncoding, EsploraError);
+impl_error!(bitcoin::hashes::hex::Error, Hex, EsploraError);
+
+#[cfg(test)]
+#[cfg(feature = "test-esplora")]
+crate::bdk_blockchain_tests! {
+    fn test_instance(test_client: &TestClient) -> EsploraBlockchain {
+        EsploraBlockchain::new(&format!("http://{}",test_client.electrsd.esplora_url.as_ref().unwrap()), 20)
+    }
+}
+
+const DEFAULT_CONCURRENT_REQUESTS: u8 = 4;
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn feerate_parsing() {
+        let esplora_fees = serde_json::from_str::<HashMap<String, f64>>(
+            r#"{
+  "25": 1.015,
+  "5": 2.3280000000000003,
+  "12": 2.0109999999999997,
+  "15": 1.018,
+  "17": 1.018,
+  "11": 2.0109999999999997,
+  "3": 3.01,
+  "2": 4.9830000000000005,
+  "6": 2.2359999999999998,
+  "21": 1.018,
+  "13": 1.081,
+  "7": 2.2359999999999998,
+  "8": 2.2359999999999998,
+  "16": 1.018,
+  "20": 1.018,
+  "22": 1.017,
+  "23": 1.017,
+  "504": 1,
+  "9": 2.2359999999999998,
+  "14": 1.018,
+  "10": 2.0109999999999997,
+  "24": 1.017,
+  "1008": 1,
+  "1": 4.9830000000000005,
+  "4": 2.3280000000000003,
+  "19": 1.018,
+  "144": 1,
+  "18": 1.018
+}
+"#,
+        )
+        .unwrap();
+        assert_eq!(
+            into_fee_rate(6, esplora_fees.clone()).unwrap(),
+            FeeRate::from_sat_per_vb(2.236)
+        );
+        assert_eq!(
+            into_fee_rate(26, esplora_fees).unwrap(),
+            FeeRate::from_sat_per_vb(1.015),
+            "should inherit from value for 25"
+        );
+    }
+}

src/blockchain/esplora/reqwest.rs

@@ -0,0 +1,337 @@
+// Bitcoin Dev Kit
+// Written in 2020 by Alekos Filini <alekos.filini@gmail.com>
+//
+// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Esplora by way of `reqwest` HTTP client.
+
+use std::collections::{HashMap, HashSet};
+
+use bitcoin::consensus::{deserialize, serialize};
+use bitcoin::hashes::hex::{FromHex, ToHex};
+use bitcoin::hashes::{sha256, Hash};
+use bitcoin::{BlockHeader, Script, Transaction, Txid};
+
+#[allow(unused_imports)]
+use log::{debug, error, info, trace};
+
+use ::reqwest::{Client, StatusCode};
+use futures::stream::{FuturesOrdered, TryStreamExt};
+
+use super::api::Tx;
+use crate::blockchain::esplora::EsploraError;
+use crate::blockchain::*;
+use crate::database::BatchDatabase;
+use crate::error::Error;
+use crate::FeeRate;
+
+#[derive(Debug)]
+struct UrlClient {
+    url: String,
+    // We use the async client instead of the blocking one because it automatically uses `fetch`
+    // when the target platform is wasm32.
+    client: Client,
+    concurrency: u8,
+}
+
+/// Structure that implements the logic to sync with Esplora
+///
+/// ## Example
+/// See the [`blockchain::esplora`](crate::blockchain::esplora) module for a usage example.
+#[derive(Debug)]
+pub struct EsploraBlockchain {
+    url_client: UrlClient,
+    stop_gap: usize,
+}
+
+impl std::convert::From<UrlClient> for EsploraBlockchain {
+    fn from(url_client: UrlClient) -> Self {
+        EsploraBlockchain {
+            url_client,
+            stop_gap: 20,
+        }
+    }
+}
+
+impl EsploraBlockchain {
+    /// Create a new instance of the client from a base URL and `stop_gap`.
+    pub fn new(base_url: &str, stop_gap: usize) -> Self {
+        EsploraBlockchain {
+            url_client: UrlClient {
+                url: base_url.to_string(),
+                client: Client::new(),
+                concurrency: super::DEFAULT_CONCURRENT_REQUESTS,
+            },
+            stop_gap,
+        }
+    }
+
+    /// Set the concurrency to use when doing batch queries against the Esplora instance.
+    pub fn with_concurrency(mut self, concurrency: u8) -> Self {
+        self.url_client.concurrency = concurrency;
+        self
+    }
+}
+
+#[maybe_async]
+impl Blockchain for EsploraBlockchain {
+    fn get_capabilities(&self) -> HashSet<Capability> {
+        vec![
+            Capability::FullHistory,
+            Capability::GetAnyTx,
+            Capability::AccurateFees,
+        ]
+        .into_iter()
+        .collect()
+    }
+
+    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
+        Ok(await_or_block!(self.url_client._get_tx(txid))?)
+    }
+
+    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
+        Ok(await_or_block!(self.url_client._broadcast(tx))?)
+    }
+
+    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
+        let estimates = await_or_block!(self.url_client._get_fee_estimates())?;
+        super::into_fee_rate(target, estimates)
+    }
+}
+
+#[maybe_async]
+impl GetHeight for EsploraBlockchain {
+    fn get_height(&self) -> Result<u32, Error> {
+        Ok(await_or_block!(self.url_client._get_height())?)
+    }
+}
+
+#[maybe_async]
+impl WalletSync for EsploraBlockchain {
+    fn wallet_setup<D: BatchDatabase, P: Progress>(
+        &self,
+        database: &mut D,
+        _progress_update: P,
+    ) -> Result<(), Error> {
+        use crate::blockchain::script_sync::Request;
+        let mut request = script_sync::start(database, self.stop_gap)?;
+        let mut tx_index: HashMap<Txid, Tx> = HashMap::new();
+
+        let batch_update = loop {
+            request = match request {
+                Request::Script(script_req) => {
+                    let futures: FuturesOrdered<_> = script_req
+                        .request()
+                        .take(self.url_client.concurrency as usize)
+                        .map(|script| async move {
+                            let mut related_txs: Vec<Tx> =
+                                self.url_client._scripthash_txs(script, None).await?;
+
+                            let n_confirmed =
+                                related_txs.iter().filter(|tx| tx.status.confirmed).count();
+                            // esplora pages on 25 confirmed transactions. If there's 25 or more we
+                            // keep requesting to see if there's more.
+                            if n_confirmed >= 25 {
+                                loop {
+                                    let new_related_txs: Vec<Tx> = self
+                                        .url_client
+                                        ._scripthash_txs(
+                                            script,
+                                            Some(related_txs.last().unwrap().txid),
+                                        )
+                                        .await?;
+                                    let n = new_related_txs.len();
+                                    related_txs.extend(new_related_txs);
+                                    // we've reached the end
+                                    if n < 25 {
+                                        break;
+                                    }
+                                }
+                            }
+                            Result::<_, Error>::Ok(related_txs)
+                        })
+                        .collect();
+                    let txs_per_script: Vec<Vec<Tx>> = await_or_block!(futures.try_collect())?;
+                    let mut satisfaction = vec![];
+
+                    for txs in txs_per_script {
+                        satisfaction.push(
+                            txs.iter()
+                                .map(|tx| (tx.txid, tx.status.block_height))
+                                .collect(),
+                        );
+                        for tx in txs {
+                            tx_index.insert(tx.txid, tx);
+                        }
+                    }
+
+                    script_req.satisfy(satisfaction)?
+                }
+                Request::Conftime(conftime_req) => {
+                    let conftimes = conftime_req
+                        .request()
+                        .map(|txid| {
+                            tx_index
+                                .get(txid)
+                                .expect("must be in index")
+                                .confirmation_time()
+                        })
+                        .collect();
+                    conftime_req.satisfy(conftimes)?
+                }
+                Request::Tx(tx_req) => {
+                    let full_txs = tx_req
+                        .request()
+                        .map(|txid| {
+                            let tx = tx_index.get(txid).expect("must be in index");
+                            (tx.previous_outputs(), tx.to_tx())
+                        })
+                        .collect();
+                    tx_req.satisfy(full_txs)?
+                }
+                Request::Finish(batch_update) => break batch_update,
+            }
+        };
+
+        database.commit_batch(batch_update)?;
+
+        Ok(())
+    }
+}
+
+impl UrlClient {
+    async fn _get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, EsploraError> {
+        let resp = self
+            .client
+            .get(&format!("{}/tx/{}/raw", self.url, txid))
+            .send()
+            .await?;
+
+        if let StatusCode::NOT_FOUND = resp.status() {
+            return Ok(None);
+        }
+
+        Ok(Some(deserialize(&resp.error_for_status()?.bytes().await?)?))
+    }
+
+    async fn _get_tx_no_opt(&self, txid: &Txid) -> Result<Transaction, EsploraError> {
+        match self._get_tx(txid).await {
+            Ok(Some(tx)) => Ok(tx),
+            Ok(None) => Err(EsploraError::TransactionNotFound(*txid)),
+            Err(e) => Err(e),
+        }
+    }
+
+    async fn _get_header(&self, block_height: u32) -> Result<BlockHeader, EsploraError> {
+        let resp = self
+            .client
+            .get(&format!("{}/block-height/{}", self.url, block_height))
+            .send()
+            .await?;
+
+        if let StatusCode::NOT_FOUND = resp.status() {
+            return Err(EsploraError::HeaderHeightNotFound(block_height));
+        }
+        let bytes = resp.bytes().await?;
+        let hash = std::str::from_utf8(&bytes)
+            .map_err(|_| EsploraError::HeaderHeightNotFound(block_height))?;
+
+        let resp = self
+            .client
+            .get(&format!("{}/block/{}/header", self.url, hash))
+            .send()
+            .await?;
+
+        let header = deserialize(&Vec::from_hex(&resp.text().await?)?)?;
+
+        Ok(header)
+    }
+
+    async fn _broadcast(&self, transaction: &Transaction) -> Result<(), EsploraError> {
+        self.client
+            .post(&format!("{}/tx", self.url))
+            .body(serialize(transaction).to_hex())
+            .send()
+            .await?
+            .error_for_status()?;
+
+        Ok(())
+    }
+
+    async fn _get_height(&self) -> Result<u32, EsploraError> {
+        let req = self
+            .client
+            .get(&format!("{}/blocks/tip/height", self.url))
+            .send()
+            .await?;
+
+        Ok(req.error_for_status()?.text().await?.parse()?)
+    }
+
+    async fn _scripthash_txs(
+        &self,
+        script: &Script,
+        last_seen: Option<Txid>,
+    ) -> Result<Vec<Tx>, EsploraError> {
+        let script_hash = sha256::Hash::hash(script.as_bytes()).into_inner().to_hex();
+        let url = match last_seen {
+            Some(last_seen) => format!(
+                "{}/scripthash/{}/txs/chain/{}",
+                self.url, script_hash, last_seen
+            ),
+            None => format!("{}/scripthash/{}/txs", self.url, script_hash),
+        };
+        Ok(self
+            .client
+            .get(url)
+            .send()
+            .await?
+            .error_for_status()?
+            .json::<Vec<Tx>>()
+            .await?)
+    }
+
+    async fn _get_fee_estimates(&self) -> Result<HashMap<String, f64>, EsploraError> {
+        Ok(self
+            .client
+            .get(&format!("{}/fee-estimates", self.url,))
+            .send()
+            .await?
+            .error_for_status()?
+            .json::<HashMap<String, f64>>()
+            .await?)
+    }
+}
+
+impl ConfigurableBlockchain for EsploraBlockchain {
+    type Config = super::EsploraBlockchainConfig;
+
+    fn from_config(config: &Self::Config) -> Result<Self, Error> {
+        let map_e = |e: reqwest::Error| Error::Esplora(Box::new(e.into()));
+
+        let mut blockchain = EsploraBlockchain::new(config.base_url.as_str(), config.stop_gap);
+        if let Some(concurrency) = config.concurrency {
+            blockchain.url_client.concurrency = concurrency;
+        }
+        let mut builder = Client::builder();
+        #[cfg(not(target_arch = "wasm32"))]
+        if let Some(proxy) = &config.proxy {
+            builder = builder.proxy(reqwest::Proxy::all(proxy).map_err(map_e)?);
+        }
+
+        #[cfg(not(target_arch = "wasm32"))]
+        if let Some(timeout) = config.timeout {
+            builder = builder.timeout(core::time::Duration::from_secs(timeout));
+        }
+
+        blockchain.url_client.client = builder.build().map_err(map_e)?;
+
+        Ok(blockchain)
+    }
+}

src/blockchain/esplora/ureq.rs

@@ -0,0 +1,375 @@
+// Bitcoin Dev Kit
+// Written in 2020 by Alekos Filini <alekos.filini@gmail.com>
+//
+// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Esplora by way of `ureq` HTTP client.
+
+use std::collections::{HashMap, HashSet};
+use std::io;
+use std::io::Read;
+use std::time::Duration;
+
+#[allow(unused_imports)]
+use log::{debug, error, info, trace};
+
+use ureq::{Agent, Proxy, Response};
+
+use bitcoin::consensus::{deserialize, serialize};
+use bitcoin::hashes::hex::{FromHex, ToHex};
+use bitcoin::hashes::{sha256, Hash};
+use bitcoin::{BlockHeader, Script, Transaction, Txid};
+
+use super::api::Tx;
+use crate::blockchain::esplora::EsploraError;
+use crate::blockchain::*;
+use crate::database::BatchDatabase;
+use crate::error::Error;
+use crate::FeeRate;
+
+#[derive(Debug, Clone)]
+struct UrlClient {
+    url: String,
+    agent: Agent,
+}
+
+/// Structure that implements the logic to sync with Esplora
+///
+/// ## Example
+/// See the [`blockchain::esplora`](crate::blockchain::esplora) module for a usage example.
+#[derive(Debug)]
+pub struct EsploraBlockchain {
+    url_client: UrlClient,
+    stop_gap: usize,
+    concurrency: u8,
+}
+
+impl EsploraBlockchain {
+    /// Create a new instance of the client from a base URL and the `stop_gap`.
+    pub fn new(base_url: &str, stop_gap: usize) -> Self {
+        EsploraBlockchain {
+            url_client: UrlClient {
+                url: base_url.to_string(),
+                agent: Agent::new(),
+            },
+            concurrency: super::DEFAULT_CONCURRENT_REQUESTS,
+            stop_gap,
+        }
+    }
+
+    /// Set the inner `ureq` agent.
+    pub fn with_agent(mut self, agent: Agent) -> Self {
+        self.url_client.agent = agent;
+        self
+    }
+
+    /// Set the number of parallel requests the client can make.
+    pub fn with_concurrency(mut self, concurrency: u8) -> Self {
+        self.concurrency = concurrency;
+        self
+    }
+}
+
+impl Blockchain for EsploraBlockchain {
+    fn get_capabilities(&self) -> HashSet<Capability> {
+        vec![
+            Capability::FullHistory,
+            Capability::GetAnyTx,
+            Capability::AccurateFees,
+        ]
+        .into_iter()
+        .collect()
+    }
+
+    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
+        Ok(self.url_client._get_tx(txid)?)
+    }
+
+    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
+        let _txid = self.url_client._broadcast(tx)?;
+        Ok(())
+    }
+
+    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
+        let estimates = self.url_client._get_fee_estimates()?;
+        super::into_fee_rate(target, estimates)
+    }
+}
+
+impl GetHeight for EsploraBlockchain {
+    fn get_height(&self) -> Result<u32, Error> {
+        Ok(self.url_client._get_height()?)
+    }
+}
+
+impl WalletSync for EsploraBlockchain {
+    fn wallet_setup<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        _progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        use crate::blockchain::script_sync::Request;
+        let mut request = script_sync::start(database, self.stop_gap)?;
+        let mut tx_index: HashMap<Txid, Tx> = HashMap::new();
+        let batch_update = loop {
+            request = match request {
+                Request::Script(script_req) => {
+                    let scripts = script_req
+                        .request()
+                        .take(self.concurrency as usize)
+                        .cloned();
+
+                    let handles = scripts.map(move |script| {
+                        let client = self.url_client.clone();
+                        // make each request in its own thread.
+                        std::thread::spawn(move || {
+                            let mut related_txs: Vec<Tx> = client._scripthash_txs(&script, None)?;
+
+                            let n_confirmed =
+                                related_txs.iter().filter(|tx| tx.status.confirmed).count();
+                            // esplora pages on 25 confirmed transactions. If there's 25 or more we
+                            // keep requesting to see if there's more.
+                            if n_confirmed >= 25 {
+                                loop {
+                                    let new_related_txs: Vec<Tx> = client._scripthash_txs(
+                                        &script,
+                                        Some(related_txs.last().unwrap().txid),
+                                    )?;
+                                    let n = new_related_txs.len();
+                                    related_txs.extend(new_related_txs);
+                                    // we've reached the end
+                                    if n < 25 {
+                                        break;
+                                    }
+                                }
+                            }
+                            Result::<_, Error>::Ok(related_txs)
+                        })
+                    });
+
+                    let txs_per_script: Vec<Vec<Tx>> = handles
+                        .map(|handle| handle.join().unwrap())
+                        .collect::<Result<_, _>>()?;
+                    let mut satisfaction = vec![];
+
+                    for txs in txs_per_script {
+                        satisfaction.push(
+                            txs.iter()
+                                .map(|tx| (tx.txid, tx.status.block_height))
+                                .collect(),
+                        );
+                        for tx in txs {
+                            tx_index.insert(tx.txid, tx);
+                        }
+                    }
+
+                    script_req.satisfy(satisfaction)?
+                }
+                Request::Conftime(conftime_req) => {
+                    let conftimes = conftime_req
+                        .request()
+                        .map(|txid| {
+                            tx_index
+                                .get(txid)
+                                .expect("must be in index")
+                                .confirmation_time()
+                        })
+                        .collect();
+                    conftime_req.satisfy(conftimes)?
+                }
+                Request::Tx(tx_req) => {
+                    let full_txs = tx_req
+                        .request()
+                        .map(|txid| {
+                            let tx = tx_index.get(txid).expect("must be in index");
+                            (tx.previous_outputs(), tx.to_tx())
+                        })
+                        .collect();
+                    tx_req.satisfy(full_txs)?
+                }
+                Request::Finish(batch_update) => break batch_update,
+            }
+        };
+
+        database.commit_batch(batch_update)?;
+
+        Ok(())
+    }
+}
+
+impl UrlClient {
+    fn _get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, EsploraError> {
+        let resp = self
+            .agent
+            .get(&format!("{}/tx/{}/raw", self.url, txid))
+            .call();
+
+        match resp {
+            Ok(resp) => Ok(Some(deserialize(&into_bytes(resp)?)?)),
+            Err(ureq::Error::Status(code, _)) => {
+                if is_status_not_found(code) {
+                    return Ok(None);
+                }
+                Err(EsploraError::HttpResponse(code))
+            }
+            Err(e) => Err(EsploraError::Ureq(e)),
+        }
+    }
+
+    fn _get_tx_no_opt(&self, txid: &Txid) -> Result<Transaction, EsploraError> {
+        match self._get_tx(txid) {
+            Ok(Some(tx)) => Ok(tx),
+            Ok(None) => Err(EsploraError::TransactionNotFound(*txid)),
+            Err(e) => Err(e),
+        }
+    }
+
+    fn _get_header(&self, block_height: u32) -> Result<BlockHeader, EsploraError> {
+        let resp = self
+            .agent
+            .get(&format!("{}/block-height/{}", self.url, block_height))
+            .call();
+
+        let bytes = match resp {
+            Ok(resp) => Ok(into_bytes(resp)?),
+            Err(ureq::Error::Status(code, _)) => Err(EsploraError::HttpResponse(code)),
+            Err(e) => Err(EsploraError::Ureq(e)),
+        }?;
+
+        let hash = std::str::from_utf8(&bytes)
+            .map_err(|_| EsploraError::HeaderHeightNotFound(block_height))?;
+
+        let resp = self
+            .agent
+            .get(&format!("{}/block/{}/header", self.url, hash))
+            .call();
+
+        match resp {
+            Ok(resp) => Ok(deserialize(&Vec::from_hex(&resp.into_string()?)?)?),
+            Err(ureq::Error::Status(code, _)) => Err(EsploraError::HttpResponse(code)),
+            Err(e) => Err(EsploraError::Ureq(e)),
+        }
+    }
+
+    fn _broadcast(&self, transaction: &Transaction) -> Result<(), EsploraError> {
+        let resp = self
+            .agent
+            .post(&format!("{}/tx", self.url))
+            .send_string(&serialize(transaction).to_hex());
+
+        match resp {
+            Ok(_) => Ok(()), // We do not return the txid?
+            Err(ureq::Error::Status(code, _)) => Err(EsploraError::HttpResponse(code)),
+            Err(e) => Err(EsploraError::Ureq(e)),
+        }
+    }
+
+    fn _get_height(&self) -> Result<u32, EsploraError> {
+        let resp = self
+            .agent
+            .get(&format!("{}/blocks/tip/height", self.url))
+            .call();
+
+        match resp {
+            Ok(resp) => Ok(resp.into_string()?.parse()?),
+            Err(ureq::Error::Status(code, _)) => Err(EsploraError::HttpResponse(code)),
+            Err(e) => Err(EsploraError::Ureq(e)),
+        }
+    }
+
+    fn _get_fee_estimates(&self) -> Result<HashMap<String, f64>, EsploraError> {
+        let resp = self
+            .agent
+            .get(&format!("{}/fee-estimates", self.url,))
+            .call();
+
+        let map = match resp {
+            Ok(resp) => {
+                let map: HashMap<String, f64> = resp.into_json()?;
+                Ok(map)
+            }
+            Err(ureq::Error::Status(code, _)) => Err(EsploraError::HttpResponse(code)),
+            Err(e) => Err(EsploraError::Ureq(e)),
+        }?;
+
+        Ok(map)
+    }
+
+    fn _scripthash_txs(
+        &self,
+        script: &Script,
+        last_seen: Option<Txid>,
+    ) -> Result<Vec<Tx>, EsploraError> {
+        let script_hash = sha256::Hash::hash(script.as_bytes()).into_inner().to_hex();
+        let url = match last_seen {
+            Some(last_seen) => format!(
+                "{}/scripthash/{}/txs/chain/{}",
+                self.url, script_hash, last_seen
+            ),
+            None => format!("{}/scripthash/{}/txs", self.url, script_hash),
+        };
+        Ok(self.agent.get(&url).call()?.into_json()?)
+    }
+}
+
+fn is_status_not_found(status: u16) -> bool {
+    status == 404
+}
+
+fn into_bytes(resp: Response) -> Result<Vec<u8>, io::Error> {
+    const BYTES_LIMIT: usize = 10 * 1_024 * 1_024;
+
+    let mut buf: Vec<u8> = vec![];
+    resp.into_reader()
+        .take((BYTES_LIMIT + 1) as u64)
+        .read_to_end(&mut buf)?;
+    if buf.len() > BYTES_LIMIT {
+        return Err(io::Error::new(
+            io::ErrorKind::Other,
+            "response too big for into_bytes",
+        ));
+    }
+
+    Ok(buf)
+}
+
+impl ConfigurableBlockchain for EsploraBlockchain {
+    type Config = super::EsploraBlockchainConfig;
+
+    fn from_config(config: &Self::Config) -> Result<Self, Error> {
+        let mut agent_builder = ureq::AgentBuilder::new();
+
+        if let Some(timeout) = config.timeout {
+            agent_builder = agent_builder.timeout(Duration::from_secs(timeout));
+        }
+
+        if let Some(proxy) = &config.proxy {
+            agent_builder = agent_builder
+                .proxy(Proxy::new(proxy).map_err(|e| Error::Esplora(Box::new(e.into())))?);
+        }
+
+        let mut blockchain = EsploraBlockchain::new(config.base_url.as_str(), config.stop_gap)
+            .with_agent(agent_builder.build());
+
+        if let Some(concurrency) = config.concurrency {
+            blockchain = blockchain.with_concurrency(concurrency);
+        }
+
+        Ok(blockchain)
+    }
+}
+
+impl From<ureq::Error> for EsploraError {
+    fn from(e: ureq::Error) -> Self {
+        match e {
+            ureq::Error::Status(code, _) => EsploraError::HttpResponse(code),
+            e => EsploraError::Ureq(e),
+        }
+    }
+}

src/blockchain/mod.rs

@@ -27,12 +27,21 @@ use crate::database::BatchDatabase;
 use crate::error::Error;
 use crate::FeeRate;
 
-#[cfg(any(feature = "electrum", feature = "esplora"))]
-pub(crate) mod utils;
-
-#[cfg(any(feature = "electrum", feature = "esplora", feature = "compact_filters"))]
+#[cfg(any(
+    feature = "electrum",
+    feature = "esplora",
+    feature = "compact_filters",
+    feature = "rpc"
+))]
 pub mod any;
-#[cfg(any(feature = "electrum", feature = "esplora", feature = "compact_filters"))]
+mod script_sync;
+
+#[cfg(any(
+    feature = "electrum",
+    feature = "esplora",
+    feature = "compact_filters",
+    feature = "rpc"
+))]
 pub use any::{AnyBlockchain, AnyBlockchainConfig};
 
 #[cfg(feature = "electrum")]
@@ -43,6 +52,14 @@ pub use self::electrum::ElectrumBlockchain;
 #[cfg(feature = "electrum")]
 pub use self::electrum::ElectrumBlockchainConfig;
 
+#[cfg(feature = "rpc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "rpc")))]
+pub mod rpc;
+#[cfg(feature = "rpc")]
+pub use self::rpc::RpcBlockchain;
+#[cfg(feature = "rpc")]
+pub use self::rpc::RpcConfig;
+
 #[cfg(feature = "esplora")]
 #[cfg_attr(docsrs, doc(cfg(feature = "esplora")))]
 pub mod esplora;
@@ -52,6 +69,7 @@ pub use self::esplora::EsploraBlockchain;
 #[cfg(feature = "compact_filters")]
 #[cfg_attr(docsrs, doc(cfg(feature = "compact_filters")))]
 pub mod compact_filters;
+
 #[cfg(feature = "compact_filters")]
 pub use self::compact_filters::CompactFiltersBlockchain;
 
@@ -68,29 +86,45 @@ pub enum Capability {
 
 /// Trait that defines the actions that must be supported by a blockchain backend
 #[maybe_async]
-pub trait Blockchain {
+pub trait Blockchain: WalletSync + GetHeight {
     /// Return the set of [`Capability`] supported by this backend
     fn get_capabilities(&self) -> HashSet<Capability>;
+    /// Fetch a transaction from the blockchain given its txid
+    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error>;
+    /// Broadcast a transaction
+    fn broadcast(&self, tx: &Transaction) -> Result<(), Error>;
+    /// Estimate the fee rate required to confirm a transaction in a given `target` of blocks
+    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error>;
+}
 
+/// Trait for getting the current height of the blockchain.
+#[maybe_async]
+pub trait GetHeight {
+    /// Return the current height
+    fn get_height(&self) -> Result<u32, Error>;
+}
+
+/// Trait for blockchains that can sync by updating the database directly.
+#[maybe_async]
+pub trait WalletSync {
     /// Setup the backend and populate the internal database for the first time
     ///
-    /// This method is the equivalent of [`Blockchain::sync`], but it's guaranteed to only be
+    /// This method is the equivalent of [`Self::wallet_sync`], but it's guaranteed to only be
     /// called once, at the first [`Wallet::sync`](crate::wallet::Wallet::sync).
     ///
     /// The rationale behind the distinction between `sync` and `setup` is that some custom backends
     /// might need to perform specific actions only the first time they are synced.
     ///
     /// For types that do not have that distinction, only this method can be implemented, since
-    /// [`Blockchain::sync`] defaults to calling this internally if not overridden.
-    fn setup<D: BatchDatabase, P: 'static + Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error>;
+    /// [`WalletSync::wallet_sync`] defaults to calling this internally if not overridden.
     /// Populate the internal database with transactions and UTXOs
-    ///
-    /// If not overridden, it defaults to calling [`Blockchain::setup`] internally.
+    fn wallet_setup<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error>;
+
+    /// If not overridden, it defaults to calling [`Self::wallet_setup`] internally.
     ///
     /// This method should implement the logic required to iterate over the list of the wallet's
     /// script_pubkeys using [`Database::iter_script_pubkeys`] and look for relevant transactions
@@ -107,24 +141,13 @@ pub trait Blockchain {
     /// [`BatchOperations::set_tx`]: crate::database::BatchOperations::set_tx
     /// [`BatchOperations::set_utxo`]: crate::database::BatchOperations::set_utxo
     /// [`BatchOperations::del_utxo`]: crate::database::BatchOperations::del_utxo
-    fn sync<D: BatchDatabase, P: 'static + Progress>(
+    fn wallet_sync<D: BatchDatabase>(
         &self,
-        stop_gap: Option<usize>,
         database: &mut D,
-        progress_update: P,
+        progress_update: Box<dyn Progress>,
     ) -> Result<(), Error> {
-        maybe_await!(self.setup(stop_gap, database, progress_update))
+        maybe_await!(self.wallet_setup(database, progress_update))
     }
-
-    /// Fetch a transaction from the blockchain given its txid
-    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error>;
-    /// Broadcast a transaction
-    fn broadcast(&self, tx: &Transaction) -> Result<(), Error>;
-
-    /// Return the current height
-    fn get_height(&self) -> Result<u32, Error>;
-    /// Estimate the fee rate required to confirm a transaction in a given `target` of blocks
-    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error>;
 }
 
 /// Trait for [`Blockchain`] types that can be created given a configuration
@@ -139,9 +162,9 @@ pub trait ConfigurableBlockchain: Blockchain + Sized {
 /// Data sent with a progress update over a [`channel`]
 pub type ProgressData = (f32, Option<String>);
 
-/// Trait for types that can receive and process progress updates during [`Blockchain::sync`] and
-/// [`Blockchain::setup`]
-pub trait Progress: Send {
+/// Trait for types that can receive and process progress updates during [`WalletSync::wallet_sync`] and
+/// [`WalletSync::wallet_setup`]
+pub trait Progress: Send + 'static + core::fmt::Debug {
     /// Send a new progress update
     ///
     /// The `progress` value should be in the range 0.0 - 100.0, and the `message` value is an
@@ -166,7 +189,7 @@ impl Progress for Sender<ProgressData> {
 }
 
 /// Type that implements [`Progress`] and drops every update received
-#[derive(Clone)]
+#[derive(Clone, Copy, Default, Debug)]
 pub struct NoopProgress;
 
 /// Create a new instance of [`NoopProgress`]
@@ -181,10 +204,10 @@ impl Progress for NoopProgress {
 }
 
 /// Type that implements [`Progress`] and logs at level `INFO` every update received
-#[derive(Clone)]
+#[derive(Clone, Copy, Default, Debug)]
 pub struct LogProgress;
 
-/// Create a nwe instance of [`LogProgress`]
+/// Create a new instance of [`LogProgress`]
 pub fn log_progress() -> LogProgress {
     LogProgress
 }
@@ -207,24 +230,6 @@ impl<T: Blockchain> Blockchain for Arc<T> {
         maybe_await!(self.deref().get_capabilities())
     }
 
-    fn setup<D: BatchDatabase, P: 'static + Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error> {
-        maybe_await!(self.deref().setup(stop_gap, database, progress_update))
-    }
-
-    fn sync<D: BatchDatabase, P: 'static + Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        database: &mut D,
-        progress_update: P,
-    ) -> Result<(), Error> {
-        maybe_await!(self.deref().sync(stop_gap, database, progress_update))
-    }
-
     fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
         maybe_await!(self.deref().get_tx(txid))
     }
@@ -232,10 +237,33 @@ impl<T: Blockchain> Blockchain for Arc<T> {
         maybe_await!(self.deref().broadcast(tx))
     }
 
-    fn get_height(&self) -> Result<u32, Error> {
-        maybe_await!(self.deref().get_height())
-    }
     fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
         maybe_await!(self.deref().estimate_fee(target))
     }
 }
+
+#[maybe_async]
+impl<T: GetHeight> GetHeight for Arc<T> {
+    fn get_height(&self) -> Result<u32, Error> {
+        maybe_await!(self.deref().get_height())
+    }
+}
+
+#[maybe_async]
+impl<T: WalletSync> WalletSync for Arc<T> {
+    fn wallet_setup<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        maybe_await!(self.deref().wallet_setup(database, progress_update))
+    }
+
+    fn wallet_sync<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        maybe_await!(self.deref().wallet_sync(database, progress_update))
+    }
+}

src/blockchain/rpc.rs

@@ -0,0 +1,452 @@
+// Bitcoin Dev Kit
+// Written in 2021 by Riccardo Casatta <riccardo@casatta.it>
+//
+// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Rpc Blockchain
+//!
+//! Backend that gets blockchain data from Bitcoin Core RPC
+//!
+//! This is an **EXPERIMENTAL** feature, API and other major changes are expected.
+//!
+//! ## Example
+//!
+//! ```no_run
+//! # use bdk::blockchain::{RpcConfig, RpcBlockchain, ConfigurableBlockchain, rpc::Auth};
+//! let config = RpcConfig {
+//!     url: "127.0.0.1:18332".to_string(),
+//!     auth: Auth::Cookie {
+//!         file: "/home/user/.bitcoin/.cookie".into(),
+//!     },
+//!     network: bdk::bitcoin::Network::Testnet,
+//!     wallet_name: "wallet_name".to_string(),
+//!     skip_blocks: None,
+//! };
+//! let blockchain = RpcBlockchain::from_config(&config);
+//! ```
+
+use crate::bitcoin::consensus::deserialize;
+use crate::bitcoin::{Address, Network, OutPoint, Transaction, TxOut, Txid};
+use crate::blockchain::{
+    Blockchain, Capability, ConfigurableBlockchain, GetHeight, Progress, WalletSync,
+};
+use crate::database::{BatchDatabase, DatabaseUtils};
+use crate::{BlockTime, Error, FeeRate, KeychainKind, LocalUtxo, TransactionDetails};
+use bitcoincore_rpc::json::{
+    GetAddressInfoResultLabel, ImportMultiOptions, ImportMultiRequest,
+    ImportMultiRequestScriptPubkey, ImportMultiRescanSince,
+};
+use bitcoincore_rpc::jsonrpc::serde_json::Value;
+use bitcoincore_rpc::Auth as RpcAuth;
+use bitcoincore_rpc::{Client, RpcApi};
+use log::debug;
+use serde::{Deserialize, Serialize};
+use std::collections::{HashMap, HashSet};
+use std::path::PathBuf;
+use std::str::FromStr;
+
+/// The main struct for RPC backend implementing the [crate::blockchain::Blockchain] trait
+#[derive(Debug)]
+pub struct RpcBlockchain {
+    /// Rpc client to the node, includes the wallet name
+    client: Client,
+    /// Network used
+    network: Network,
+    /// Blockchain capabilities, cached here at startup
+    capabilities: HashSet<Capability>,
+    /// Skip this many blocks of the blockchain at the first rescan, if None the rescan is done from the genesis block
+    skip_blocks: Option<u32>,
+
+    /// This is a fixed Address used as a hack key to store information on the node
+    _storage_address: Address,
+}
+
+/// RpcBlockchain configuration options
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
+pub struct RpcConfig {
+    /// The bitcoin node url
+    pub url: String,
+    /// The bitcoin node authentication mechanism
+    pub auth: Auth,
+    /// The network we are using (it will be checked the bitcoin node network matches this)
+    pub network: Network,
+    /// The wallet name in the bitcoin node, consider using [crate::wallet::wallet_name_from_descriptor] for this
+    pub wallet_name: String,
+    /// Skip this many blocks of the blockchain at the first rescan, if None the rescan is done from the genesis block
+    pub skip_blocks: Option<u32>,
+}
+
+/// This struct is equivalent to [bitcoincore_rpc::Auth] but it implements [serde::Serialize]
+/// To be removed once upstream equivalent is implementing Serialize (json serialization format
+/// should be the same), see [rust-bitcoincore-rpc/pull/181](https://github.com/rust-bitcoin/rust-bitcoincore-rpc/pull/181)
+#[derive(Clone, Debug, Hash, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+#[serde(untagged)]
+pub enum Auth {
+    /// None authentication
+    None,
+    /// Authentication with username and password, usually [Auth::Cookie] should be preferred
+    UserPass {
+        /// Username
+        username: String,
+        /// Password
+        password: String,
+    },
+    /// Authentication with a cookie file
+    Cookie {
+        /// Cookie file
+        file: PathBuf,
+    },
+}
+
+impl From<Auth> for RpcAuth {
+    fn from(auth: Auth) -> Self {
+        match auth {
+            Auth::None => RpcAuth::None,
+            Auth::UserPass { username, password } => RpcAuth::UserPass(username, password),
+            Auth::Cookie { file } => RpcAuth::CookieFile(file),
+        }
+    }
+}
+
+impl RpcBlockchain {
+    fn get_node_synced_height(&self) -> Result<u32, Error> {
+        let info = self.client.get_address_info(&self._storage_address)?;
+        if let Some(GetAddressInfoResultLabel::Simple(label)) = info.labels.first() {
+            Ok(label
+                .parse::<u32>()
+                .unwrap_or_else(|_| self.skip_blocks.unwrap_or(0)))
+        } else {
+            Ok(self.skip_blocks.unwrap_or(0))
+        }
+    }
+
+    /// Set the synced height in the core node by using a label of a fixed address so that
+    /// another client with the same descriptor doesn't rescan the blockchain
+    fn set_node_synced_height(&self, height: u32) -> Result<(), Error> {
+        Ok(self
+            .client
+            .set_label(&self._storage_address, &height.to_string())?)
+    }
+}
+
+impl Blockchain for RpcBlockchain {
+    fn get_capabilities(&self) -> HashSet<Capability> {
+        self.capabilities.clone()
+    }
+
+    fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
+        Ok(Some(self.client.get_raw_transaction(txid, None)?))
+    }
+
+    fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
+        Ok(self.client.send_raw_transaction(tx).map(|_| ())?)
+    }
+
+    fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
+        let sat_per_kb = self
+            .client
+            .estimate_smart_fee(target as u16, None)?
+            .fee_rate
+            .ok_or(Error::FeeRateUnavailable)?
+            .as_sat() as f64;
+
+        Ok(FeeRate::from_sat_per_vb((sat_per_kb / 1000f64) as f32))
+    }
+}
+
+impl GetHeight for RpcBlockchain {
+    fn get_height(&self) -> Result<u32, Error> {
+        Ok(self.client.get_blockchain_info().map(|i| i.blocks as u32)?)
+    }
+}
+
+impl WalletSync for RpcBlockchain {
+    fn wallet_setup<D: BatchDatabase>(
+        &self,
+        database: &mut D,
+        progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        let mut scripts_pubkeys = database.iter_script_pubkeys(Some(KeychainKind::External))?;
+        scripts_pubkeys.extend(database.iter_script_pubkeys(Some(KeychainKind::Internal))?);
+        debug!(
+            "importing {} script_pubkeys (some maybe already imported)",
+            scripts_pubkeys.len()
+        );
+        let requests: Vec<_> = scripts_pubkeys
+            .iter()
+            .map(|s| ImportMultiRequest {
+                timestamp: ImportMultiRescanSince::Timestamp(0),
+                script_pubkey: Some(ImportMultiRequestScriptPubkey::Script(s)),
+                watchonly: Some(true),
+                ..Default::default()
+            })
+            .collect();
+        let options = ImportMultiOptions {
+            rescan: Some(false),
+        };
+        // Note we use import_multi because as of bitcoin core 0.21.0 many descriptors are not supported
+        // https://bitcoindevkit.org/descriptors/#compatibility-matrix
+        //TODO maybe convenient using import_descriptor for compatible descriptor and import_multi as fallback
+        self.client.import_multi(&requests, Some(&options))?;
+
+        loop {
+            let current_height = self.get_height()?;
+
+            // min because block invalidate may cause height to go down
+            let node_synced = self.get_node_synced_height()?.min(current_height);
+
+            let sync_up_to = node_synced.saturating_add(10_000).min(current_height);
+
+            debug!("rescan_blockchain from:{} to:{}", node_synced, sync_up_to);
+            self.client
+                .rescan_blockchain(Some(node_synced as usize), Some(sync_up_to as usize))?;
+            progress_update.update((sync_up_to as f32) / (current_height as f32), None)?;
+
+            self.set_node_synced_height(sync_up_to)?;
+
+            if sync_up_to == current_height {
+                break;
+            }
+        }
+
+        self.wallet_sync(database, progress_update)
+    }
+
+    fn wallet_sync<D: BatchDatabase>(
+        &self,
+        db: &mut D,
+        _progress_update: Box<dyn Progress>,
+    ) -> Result<(), Error> {
+        let mut indexes = HashMap::new();
+        for keykind in &[KeychainKind::External, KeychainKind::Internal] {
+            indexes.insert(*keykind, db.get_last_index(*keykind)?.unwrap_or(0));
+        }
+
+        let mut known_txs: HashMap<_, _> = db
+            .iter_txs(true)?
+            .into_iter()
+            .map(|tx| (tx.txid, tx))
+            .collect();
+        let known_utxos: HashSet<_> = db.iter_utxos()?.into_iter().collect();
+
+        //TODO list_since_blocks would be more efficient
+        let current_utxo = self
+            .client
+            .list_unspent(Some(0), None, None, Some(true), None)?;
+        debug!("current_utxo len {}", current_utxo.len());
+
+        //TODO supported up to 1_000 txs, should use since_blocks or do paging
+        let list_txs = self
+            .client
+            .list_transactions(None, Some(1_000), None, Some(true))?;
+        let mut list_txs_ids = HashSet::new();
+
+        for tx_result in list_txs.iter().filter(|t| {
+            // list_txs returns all conflicting tx we want to
+            // filter out replaced tx => unconfirmed and not in the mempool
+            t.info.confirmations > 0 || self.client.get_mempool_entry(&t.info.txid).is_ok()
+        }) {
+            let txid = tx_result.info.txid;
+            list_txs_ids.insert(txid);
+            if let Some(mut known_tx) = known_txs.get_mut(&txid) {
+                let confirmation_time =
+                    BlockTime::new(tx_result.info.blockheight, tx_result.info.blocktime);
+                if confirmation_time != known_tx.confirmation_time {
+                    // reorg may change tx height
+                    debug!(
+                        "updating tx({}) confirmation time to: {:?}",
+                        txid, confirmation_time
+                    );
+                    known_tx.confirmation_time = confirmation_time;
+                    db.set_tx(known_tx)?;
+                }
+            } else {
+                //TODO check there is already the raw tx in db?
+                let tx_result = self.client.get_transaction(&txid, Some(true))?;
+                let tx: Transaction = deserialize(&tx_result.hex)?;
+                let mut received = 0u64;
+                let mut sent = 0u64;
+                for output in tx.output.iter() {
+                    if let Ok(Some((kind, index))) =
+                        db.get_path_from_script_pubkey(&output.script_pubkey)
+                    {
+                        if index > *indexes.get(&kind).unwrap() {
+                            indexes.insert(kind, index);
+                        }
+                        received += output.value;
+                    }
+                }
+
+                for input in tx.input.iter() {
+                    if let Some(previous_output) = db.get_previous_output(&input.previous_output)? {
+                        sent += previous_output.value;
+                    }
+                }
+
+                let td = TransactionDetails {
+                    transaction: Some(tx),
+                    txid: tx_result.info.txid,
+                    confirmation_time: BlockTime::new(
+                        tx_result.info.blockheight,
+                        tx_result.info.blocktime,
+                    ),
+                    received,
+                    sent,
+                    fee: tx_result.fee.map(|f| f.as_sat().abs() as u64),
+                    verified: true,
+                };
+                debug!(
+                    "saving tx: {} tx_result.fee:{:?} td.fees:{:?}",
+                    td.txid, tx_result.fee, td.fee
+                );
+                db.set_tx(&td)?;
+            }
+        }
+
+        for known_txid in known_txs.keys() {
+            if !list_txs_ids.contains(known_txid) {
+                debug!("removing tx: {}", known_txid);
+                db.del_tx(known_txid, false)?;
+            }
+        }
+
+        let current_utxos: HashSet<_> = current_utxo
+            .into_iter()
+            .map(|u| {
+                Ok(LocalUtxo {
+                    outpoint: OutPoint::new(u.txid, u.vout),
+                    keychain: db
+                        .get_path_from_script_pubkey(&u.script_pub_key)?
+                        .ok_or(Error::TransactionNotFound)?
+                        .0,
+                    txout: TxOut {
+                        value: u.amount.as_sat(),
+                        script_pubkey: u.script_pub_key,
+                    },
+                })
+            })
+            .collect::<Result<_, Error>>()?;
+
+        let spent: HashSet<_> = known_utxos.difference(&current_utxos).collect();
+        for s in spent {
+            debug!("removing utxo: {:?}", s);
+            db.del_utxo(&s.outpoint)?;
+        }
+        let received: HashSet<_> = current_utxos.difference(&known_utxos).collect();
+        for s in received {
+            debug!("adding utxo: {:?}", s);
+            db.set_utxo(s)?;
+        }
+
+        for (keykind, index) in indexes {
+            debug!("{:?} max {}", keykind, index);
+            db.set_last_index(keykind, index)?;
+        }
+
+        Ok(())
+    }
+}
+
+impl ConfigurableBlockchain for RpcBlockchain {
+    type Config = RpcConfig;
+
+    /// Returns RpcBlockchain backend creating an RPC client to a specific wallet named as the descriptor's checksum
+    /// if it's the first time it creates the wallet in the node and upon return is granted the wallet is loaded
+    fn from_config(config: &Self::Config) -> Result<Self, Error> {
+        let wallet_name = config.wallet_name.clone();
+        let wallet_url = format!("{}/wallet/{}", config.url, &wallet_name);
+        debug!("connecting to {} auth:{:?}", wallet_url, config.auth);
+
+        let client = Client::new(wallet_url.as_str(), config.auth.clone().into())?;
+        let loaded_wallets = client.list_wallets()?;
+        if loaded_wallets.contains(&wallet_name) {
+            debug!("wallet already loaded {:?}", wallet_name);
+        } else {
+            let existing_wallets = list_wallet_dir(&client)?;
+            if existing_wallets.contains(&wallet_name) {
+                client.load_wallet(&wallet_name)?;
+                debug!("wallet loaded {:?}", wallet_name);
+            } else {
+                client.create_wallet(&wallet_name, Some(true), None, None, None)?;
+                debug!("wallet created {:?}", wallet_name);
+            }
+        }
+
+        let blockchain_info = client.get_blockchain_info()?;
+        let network = match blockchain_info.chain.as_str() {
+            "main" => Network::Bitcoin,
+            "test" => Network::Testnet,
+            "regtest" => Network::Regtest,
+            "signet" => Network::Signet,
+            _ => return Err(Error::Generic("Invalid network".to_string())),
+        };
+        if network != config.network {
+            return Err(Error::InvalidNetwork {
+                requested: config.network,
+                found: network,
+            });
+        }
+
+        let mut capabilities: HashSet<_> = vec![Capability::FullHistory].into_iter().collect();
+        let rpc_version = client.version()?;
+        if rpc_version >= 210_000 {
+            let info: HashMap<String, Value> = client.call("getindexinfo", &[]).unwrap();
+            if info.contains_key("txindex") {
+                capabilities.insert(Capability::GetAnyTx);
+                capabilities.insert(Capability::AccurateFees);
+            }
+        }
+
+        // this is just a fixed address used only to store a label containing the synced height in the node
+        let mut storage_address =
+            Address::from_str("bc1qst0rewf0wm4kw6qn6kv0e5tc56nkf9yhcxlhqv").unwrap();
+        storage_address.network = network;
+
+        Ok(RpcBlockchain {
+            client,
+            network,
+            capabilities,
+            _storage_address: storage_address,
+            skip_blocks: config.skip_blocks,
+        })
+    }
+}
+
+/// return the wallets available in default wallet directory
+//TODO use bitcoincore_rpc method when PR #179 lands
+fn list_wallet_dir(client: &Client) -> Result<Vec<String>, Error> {
+    #[derive(Deserialize)]
+    struct Name {
+        name: String,
+    }
+    #[derive(Deserialize)]
+    struct CallResult {
+        wallets: Vec<Name>,
+    }
+
+    let result: CallResult = client.call("listwalletdir", &[])?;
+    Ok(result.wallets.into_iter().map(|n| n.name).collect())
+}
+
+#[cfg(test)]
+#[cfg(feature = "test-rpc")]
+crate::bdk_blockchain_tests! {
+
+    fn test_instance(test_client: &TestClient) -> RpcBlockchain {
+        let config = RpcConfig {
+            url: test_client.bitcoind.rpc_url(),
+            auth: Auth::Cookie { file: test_client.bitcoind.params.cookie_file.clone() },
+            network: Network::Regtest,
+            wallet_name: format!("client-wallet-test-{:?}", std::time::SystemTime::now() ),
+            skip_blocks: None,
+        };
+        RpcBlockchain::from_config(&config).unwrap()
+    }
+}

src/blockchain/script_sync.rs

@@ -0,0 +1,394 @@
+/*!
+This models a how a sync happens where you have a server that you send your script pubkeys to and it
+returns associated transactions i.e. electrum.
+*/
+#![allow(dead_code)]
+use crate::{
+    database::{BatchDatabase, BatchOperations, DatabaseUtils},
+    wallet::time::Instant,
+    BlockTime, Error, KeychainKind, LocalUtxo, TransactionDetails,
+};
+use bitcoin::{OutPoint, Script, Transaction, TxOut, Txid};
+use log::*;
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet, VecDeque};
+
+/// A request for on-chain information
+pub enum Request<'a, D: BatchDatabase> {
+    /// A request for transactions related to script pubkeys.
+    Script(ScriptReq<'a, D>),
+    /// A request for confirmation times for some transactions.
+    Conftime(ConftimeReq<'a, D>),
+    /// A request for full transaction details of some transactions.
+    Tx(TxReq<'a, D>),
+    /// Requests are finished here's a batch database update to reflect data gathered.
+    Finish(D::Batch),
+}
+
+/// starts a sync
+pub fn start<D: BatchDatabase>(db: &D, stop_gap: usize) -> Result<Request<'_, D>, Error> {
+    use rand::seq::SliceRandom;
+    let mut keychains = vec![KeychainKind::Internal, KeychainKind::External];
+    // shuffling improve privacy, the server doesn't know my first request is from my internal or external addresses
+    keychains.shuffle(&mut rand::thread_rng());
+    let keychain = keychains.pop().unwrap();
+    let scripts_needed = db
+        .iter_script_pubkeys(Some(keychain))?
+        .into_iter()
+        .collect();
+    let state = State::new(db);
+
+    Ok(Request::Script(ScriptReq {
+        state,
+        scripts_needed,
+        script_index: 0,
+        stop_gap,
+        keychain,
+        next_keychains: keychains,
+    }))
+}
+
+pub struct ScriptReq<'a, D: BatchDatabase> {
+    state: State<'a, D>,
+    script_index: usize,
+    scripts_needed: VecDeque<Script>,
+    stop_gap: usize,
+    keychain: KeychainKind,
+    next_keychains: Vec<KeychainKind>,
+}
+
+/// The sync starts by returning script pubkeys we are interested in.
+impl<'a, D: BatchDatabase> ScriptReq<'a, D> {
+    pub fn request(&self) -> impl Iterator<Item = &Script> + Clone {
+        self.scripts_needed.iter()
+    }
+
+    pub fn satisfy(
+        mut self,
+        // we want to know the txids assoiciated with the script and their height
+        txids: Vec<Vec<(Txid, Option<u32>)>>,
+    ) -> Result<Request<'a, D>, Error> {
+        for (txid_list, script) in txids.iter().zip(self.scripts_needed.iter()) {
+            debug!(
+                "found {} transactions for script pubkey {}",
+                txid_list.len(),
+                script
+            );
+            if !txid_list.is_empty() {
+                // the address is active
+                self.state
+                    .last_active_index
+                    .insert(self.keychain, self.script_index);
+            }
+
+            for (txid, height) in txid_list {
+                // have we seen this txid already?
+                match self.state.db.get_tx(txid, true)? {
+                    Some(mut details) => {
+                        let old_height = details.confirmation_time.as_ref().map(|x| x.height);
+                        match (old_height, height) {
+                            (None, Some(_)) => {
+                                // It looks like the tx has confirmed since we last saw it -- we
+                                // need to know the confirmation time.
+                                self.state.tx_missing_conftime.insert(*txid, details);
+                            }
+                            (Some(old_height), Some(new_height)) if old_height != *new_height => {
+                                // The height of the tx has changed !? -- It's a reorg get the new confirmation time.
+                                self.state.tx_missing_conftime.insert(*txid, details);
+                            }
+                            (Some(_), None) => {
+                                // A re-org where the tx is not in the chain anymore.
+                                details.confirmation_time = None;
+                                self.state.finished_txs.push(details);
+                            }
+                            _ => self.state.finished_txs.push(details),
+                        }
+                    }
+                    None => {
+                        // we've never seen it let's get the whole thing
+                        self.state.tx_needed.insert(*txid);
+                    }
+                };
+            }
+
+            self.script_index += 1;
+        }
+
+        for _ in txids {
+            self.scripts_needed.pop_front();
+        }
+
+        let last_active_index = self
+            .state
+            .last_active_index
+            .get(&self.keychain)
+            .map(|x| x + 1)
+            .unwrap_or(0); // so no addresses active maps to 0
+
+        Ok(
+            if self.script_index > last_active_index + self.stop_gap
+                || self.scripts_needed.is_empty()
+            {
+                debug!(
+                    "finished scanning for transactions for keychain {:?} at index {}",
+                    self.keychain, last_active_index
+                );
+                // we're done here -- check if we need to do the next keychain
+                if let Some(keychain) = self.next_keychains.pop() {
+                    self.keychain = keychain;
+                    self.script_index = 0;
+                    self.scripts_needed = self
+                        .state
+                        .db
+                        .iter_script_pubkeys(Some(keychain))?
+                        .into_iter()
+                        .collect();
+                    Request::Script(self)
+                } else {
+                    Request::Tx(TxReq { state: self.state })
+                }
+            } else {
+                Request::Script(self)
+            },
+        )
+    }
+}
+
+/// Then we get full transactions
+pub struct TxReq<'a, D> {
+    state: State<'a, D>,
+}
+
+impl<'a, D: BatchDatabase> TxReq<'a, D> {
+    pub fn request(&self) -> impl Iterator<Item = &Txid> + Clone {
+        self.state.tx_needed.iter()
+    }
+
+    pub fn satisfy(
+        mut self,
+        tx_details: Vec<(Vec<Option<TxOut>>, Transaction)>,
+    ) -> Result<Request<'a, D>, Error> {
+        let tx_details: Vec<TransactionDetails> = tx_details
+            .into_iter()
+            .zip(self.state.tx_needed.iter())
+            .map(|((vout, tx), txid)| {
+                debug!("found tx_details for {}", txid);
+                assert_eq!(tx.txid(), *txid);
+                let mut sent: u64 = 0;
+                let mut received: u64 = 0;
+                let mut inputs_sum: u64 = 0;
+                let mut outputs_sum: u64 = 0;
+
+                for (txout, input) in vout.into_iter().zip(tx.input.iter()) {
+                    let txout = match txout {
+                        Some(txout) => txout,
+                        None => {
+                            // skip coinbase inputs
+                            debug_assert!(
+                                input.previous_output.is_null(),
+                                "prevout should only be missing for coinbase"
+                            );
+                            continue;
+                        }
+                    };
+
+                    inputs_sum += txout.value;
+                    if self.state.db.is_mine(&txout.script_pubkey)? {
+                        sent += txout.value;
+                    }
+                }
+
+                for out in &tx.output {
+                    outputs_sum += out.value;
+                    if self.state.db.is_mine(&out.script_pubkey)? {
+                        received += out.value;
+                    }
+                }
+                // we need to saturating sub since we want coinbase txs to map to 0 fee and
+                // this subtraction will be negative for coinbase txs.
+                let fee = inputs_sum.saturating_sub(outputs_sum);
+                Result::<_, Error>::Ok(TransactionDetails {
+                    txid: *txid,
+                    transaction: Some(tx),
+                    received,
+                    sent,
+                    // we're going to fill this in later
+                    confirmation_time: None,
+                    fee: Some(fee),
+                    verified: false,
+                })
+            })
+            .collect::<Result<Vec<_>, _>>()?;
+
+        for tx_detail in tx_details {
+            self.state.tx_needed.remove(&tx_detail.txid);
+            self.state
+                .tx_missing_conftime
+                .insert(tx_detail.txid, tx_detail);
+        }
+
+        if !self.state.tx_needed.is_empty() {
+            Ok(Request::Tx(self))
+        } else {
+            Ok(Request::Conftime(ConftimeReq { state: self.state }))
+        }
+    }
+}
+
+/// Final step is to get confirmation times
+pub struct ConftimeReq<'a, D> {
+    state: State<'a, D>,
+}
+
+impl<'a, D: BatchDatabase> ConftimeReq<'a, D> {
+    pub fn request(&self) -> impl Iterator<Item = &Txid> + Clone {
+        self.state.tx_missing_conftime.keys()
+    }
+
+    pub fn satisfy(
+        mut self,
+        confirmation_times: Vec<Option<BlockTime>>,
+    ) -> Result<Request<'a, D>, Error> {
+        let conftime_needed = self
+            .request()
+            .cloned()
+            .take(confirmation_times.len())
+            .collect::<Vec<_>>();
+        for (confirmation_time, txid) in confirmation_times.into_iter().zip(conftime_needed.iter())
+        {
+            debug!("confirmation time for {} was {:?}", txid, confirmation_time);
+            if let Some(mut tx_details) = self.state.tx_missing_conftime.remove(txid) {
+                tx_details.confirmation_time = confirmation_time;
+                self.state.finished_txs.push(tx_details);
+            }
+        }
+
+        if self.state.tx_missing_conftime.is_empty() {
+            Ok(Request::Finish(self.state.into_db_update()?))
+        } else {
+            Ok(Request::Conftime(self))
+        }
+    }
+}
+
+struct State<'a, D> {
+    db: &'a D,
+    last_active_index: HashMap<KeychainKind, usize>,
+    /// Transactions where we need to get the full details
+    tx_needed: BTreeSet<Txid>,
+    /// Transacitions that we know everything about
+    finished_txs: Vec<TransactionDetails>,
+    /// Transactions that discovered conftimes should be inserted into
+    tx_missing_conftime: BTreeMap<Txid, TransactionDetails>,
+    /// The start of the sync
+    start_time: Instant,
+}
+
+impl<'a, D: BatchDatabase> State<'a, D> {
+    fn new(db: &'a D) -> Self {
+        State {
+            db,
+            last_active_index: HashMap::default(),
+            finished_txs: vec![],
+            tx_needed: BTreeSet::default(),
+            tx_missing_conftime: BTreeMap::default(),
+            start_time: Instant::new(),
+        }
+    }
+    fn into_db_update(self) -> Result<D::Batch, Error> {
+        debug_assert!(self.tx_needed.is_empty() && self.tx_missing_conftime.is_empty());
+        let existing_txs = self.db.iter_txs(false)?;
+        let existing_txids: HashSet<Txid> = existing_txs.iter().map(|tx| tx.txid).collect();
+        let finished_txs = make_txs_consistent(&self.finished_txs);
+        let observed_txids: HashSet<Txid> = finished_txs.iter().map(|tx| tx.txid).collect();
+        let txids_to_delete = existing_txids.difference(&observed_txids);
+        let mut batch = self.db.begin_batch();
+
+        // Delete old txs that no longer exist
+        for txid in txids_to_delete {
+            if let Some(raw_tx) = self.db.get_raw_tx(txid)? {
+                for i in 0..raw_tx.output.len() {
+                    // Also delete any utxos from the txs that no longer exist.
+                    let _ = batch.del_utxo(&OutPoint {
+                        txid: *txid,
+                        vout: i as u32,
+                    })?;
+                }
+            } else {
+                unreachable!("we should always have the raw tx");
+            }
+            batch.del_tx(txid, true)?;
+        }
+
+        // Set every tx we observed
+        for finished_tx in &finished_txs {
+            let tx = finished_tx
+                .transaction
+                .as_ref()
+                .expect("transaction will always be present here");
+            for (i, output) in tx.output.iter().enumerate() {
+                if let Some((keychain, _)) =
+                    self.db.get_path_from_script_pubkey(&output.script_pubkey)?
+                {
+                    // add utxos we own from the new transactions we've seen.
+                    batch.set_utxo(&LocalUtxo {
+                        outpoint: OutPoint {
+                            txid: finished_tx.txid,
+                            vout: i as u32,
+                        },
+                        txout: output.clone(),
+                        keychain,
+                    })?;
+                }
+            }
+            batch.set_tx(finished_tx)?;
+        }
+
+        // we don't do this in the loop above since we may want to delete some of the utxos we
+        // just added in case there are new tranasactions that spend form each other.
+        for finished_tx in &finished_txs {
+            let tx = finished_tx
+                .transaction
+                .as_ref()
+                .expect("transaction will always be present here");
+            for input in &tx.input {
+                // Delete any spent utxos
+                batch.del_utxo(&input.previous_output)?;
+            }
+        }
+
+        for (keychain, last_active_index) in self.last_active_index {
+            batch.set_last_index(keychain, last_active_index as u32)?;
+        }
+
+        info!(
+            "finished setup, elapsed {:?}ms",
+            self.start_time.elapsed().as_millis()
+        );
+        Ok(batch)
+    }
+}
+
+/// Remove conflicting transactions -- tie breaking them by fee.
+fn make_txs_consistent(txs: &[TransactionDetails]) -> Vec<&TransactionDetails> {
+    let mut utxo_index: HashMap<OutPoint, &TransactionDetails> = HashMap::default();
+    for tx in txs {
+        for input in &tx.transaction.as_ref().unwrap().input {
+            utxo_index
+                .entry(input.previous_output)
+                .and_modify(|existing| match (tx.fee, existing.fee) {
+                    (Some(fee), Some(existing_fee)) if fee > existing_fee => *existing = tx,
+                    (Some(_), None) => *existing = tx,
+                    _ => { /* leave it the same */ }
+                })
+                .or_insert(tx);
+        }
+    }
+
+    utxo_index
+        .into_iter()
+        .map(|(_, tx)| (tx.txid, tx))
+        .collect::<HashMap<_, _>>()
+        .into_iter()
+        .map(|(_, tx)| tx)
+        .collect()
+}

src/blockchain/utils.rs

@@ -1,384 +0,0 @@
-// Bitcoin Dev Kit
-// Written in 2020 by Alekos Filini <alekos.filini@gmail.com>
-//
-// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
-//
-// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
-// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
-// You may not use this file except in accordance with one or both of these
-// licenses.
-
-use std::collections::{HashMap, HashSet};
-
-#[allow(unused_imports)]
-use log::{debug, error, info, trace};
-use rand::seq::SliceRandom;
-use rand::thread_rng;
-
-use bitcoin::{BlockHeader, OutPoint, Script, Transaction, Txid};
-
-use super::*;
-use crate::database::{BatchDatabase, BatchOperations, DatabaseUtils};
-use crate::error::Error;
-use crate::types::{KeychainKind, LocalUtxo, TransactionDetails};
-use crate::wallet::time::Instant;
-use crate::wallet::utils::ChunksIterator;
-
-#[derive(Debug)]
-pub struct ElsGetHistoryRes {
-    pub height: i32,
-    pub tx_hash: Txid,
-}
-
-/// Implements the synchronization logic for an Electrum-like client.
-#[maybe_async]
-pub trait ElectrumLikeSync {
-    fn els_batch_script_get_history<'s, I: IntoIterator<Item = &'s Script> + Clone>(
-        &self,
-        scripts: I,
-    ) -> Result<Vec<Vec<ElsGetHistoryRes>>, Error>;
-
-    fn els_batch_transaction_get<'s, I: IntoIterator<Item = &'s Txid> + Clone>(
-        &self,
-        txids: I,
-    ) -> Result<Vec<Transaction>, Error>;
-
-    fn els_batch_block_header<I: IntoIterator<Item = u32> + Clone>(
-        &self,
-        heights: I,
-    ) -> Result<Vec<BlockHeader>, Error>;
-
-    // Provided methods down here...
-
-    fn electrum_like_setup<D: BatchDatabase, P: Progress>(
-        &self,
-        stop_gap: Option<usize>,
-        db: &mut D,
-        _progress_update: P,
-    ) -> Result<(), Error> {
-        // TODO: progress
-        let start = Instant::new();
-        debug!("start setup");
-
-        let stop_gap = stop_gap.unwrap_or(20);
-        let chunk_size = stop_gap;
-
-        let mut history_txs_id = HashSet::new();
-        let mut txid_height = HashMap::new();
-        let mut max_indexes = HashMap::new();
-
-        let mut wallet_chains = vec![KeychainKind::Internal, KeychainKind::External];
-        // shuffling improve privacy, the server doesn't know my first request is from my internal or external addresses
-        wallet_chains.shuffle(&mut thread_rng());
-        // download history of our internal and external script_pubkeys
-        for keychain in wallet_chains.iter() {
-            let script_iter = db.iter_script_pubkeys(Some(*keychain))?.into_iter();
-
-            for (i, chunk) in ChunksIterator::new(script_iter, stop_gap).enumerate() {
-                // TODO if i == last, should create another chunk of addresses in db
-                let call_result: Vec<Vec<ElsGetHistoryRes>> =
-                    maybe_await!(self.els_batch_script_get_history(chunk.iter()))?;
-                let max_index = call_result
-                    .iter()
-                    .enumerate()
-                    .filter_map(|(i, v)| v.first().map(|_| i as u32))
-                    .max();
-                if let Some(max) = max_index {
-                    max_indexes.insert(keychain, max + (i * chunk_size) as u32);
-                }
-                let flattened: Vec<ElsGetHistoryRes> = call_result.into_iter().flatten().collect();
-                debug!("#{} of {:?} results:{}", i, keychain, flattened.len());
-                if flattened.is_empty() {
-                    // Didn't find anything in the last `stop_gap` script_pubkeys, breaking
-                    break;
-                }
-
-                for el in flattened {
-                    // el.height = -1 means unconfirmed with unconfirmed parents
-                    // el.height =  0 means unconfirmed with confirmed parents
-                    // but we treat those tx the same
-                    if el.height <= 0 {
-                        txid_height.insert(el.tx_hash, None);
-                    } else {
-                        txid_height.insert(el.tx_hash, Some(el.height as u32));
-                    }
-                    history_txs_id.insert(el.tx_hash);
-                }
-            }
-        }
-
-        // saving max indexes
-        info!("max indexes are: {:?}", max_indexes);
-        for keychain in wallet_chains.iter() {
-            if let Some(index) = max_indexes.get(keychain) {
-                db.set_last_index(*keychain, *index)?;
-            }
-        }
-
-        // get db status
-        let txs_details_in_db: HashMap<Txid, TransactionDetails> = db
-            .iter_txs(false)?
-            .into_iter()
-            .map(|tx| (tx.txid, tx))
-            .collect();
-        let txs_raw_in_db: HashMap<Txid, Transaction> = db
-            .iter_raw_txs()?
-            .into_iter()
-            .map(|tx| (tx.txid(), tx))
-            .collect();
-        let utxos_deps = utxos_deps(db, &txs_raw_in_db)?;
-
-        // download new txs and headers
-        let new_txs = maybe_await!(self.download_and_save_needed_raw_txs(
-            &history_txs_id,
-            &txs_raw_in_db,
-            chunk_size,
-            db
-        ))?;
-        let new_timestamps = maybe_await!(self.download_needed_headers(
-            &txid_height,
-            &txs_details_in_db,
-            chunk_size
-        ))?;
-
-        let mut batch = db.begin_batch();
-
-        // save any tx details not in db but in history_txs_id or with different height/timestamp
-        for txid in history_txs_id.iter() {
-            let height = txid_height.get(txid).cloned().flatten();
-            let timestamp = *new_timestamps.get(txid).unwrap_or(&0u64);
-            if let Some(tx_details) = txs_details_in_db.get(txid) {
-                // check if height matches, otherwise updates it
-                if tx_details.height != height {
-                    let mut new_tx_details = tx_details.clone();
-                    new_tx_details.height = height;
-                    new_tx_details.timestamp = timestamp;
-                    batch.set_tx(&new_tx_details)?;
-                }
-            } else {
-                save_transaction_details_and_utxos(
-                    &txid,
-                    db,
-                    timestamp,
-                    height,
-                    &mut batch,
-                    &utxos_deps,
-                )?;
-            }
-        }
-
-        // remove any tx details in db but not in history_txs_id
-        for txid in txs_details_in_db.keys() {
-            if !history_txs_id.contains(txid) {
-                batch.del_tx(&txid, false)?;
-            }
-        }
-
-        // remove any spent utxo
-        for new_tx in new_txs.iter() {
-            for input in new_tx.input.iter() {
-                batch.del_utxo(&input.previous_output)?;
-            }
-        }
-
-        db.commit_batch(batch)?;
-        info!("finish setup, elapsed {:?}ms", start.elapsed().as_millis());
-
-        Ok(())
-    }
-
-    /// download txs identified by `history_txs_id` and theirs previous outputs if not already present in db
-    fn download_and_save_needed_raw_txs<D: BatchDatabase>(
-        &self,
-        history_txs_id: &HashSet<Txid>,
-        txs_raw_in_db: &HashMap<Txid, Transaction>,
-        chunk_size: usize,
-        db: &mut D,
-    ) -> Result<Vec<Transaction>, Error> {
-        let mut txs_downloaded = vec![];
-        let txids_raw_in_db: HashSet<Txid> = txs_raw_in_db.keys().cloned().collect();
-        let txids_to_download: Vec<&Txid> = history_txs_id.difference(&txids_raw_in_db).collect();
-        if !txids_to_download.is_empty() {
-            info!("got {} txs to download", txids_to_download.len());
-            txs_downloaded.extend(maybe_await!(self.download_and_save_in_chunks(
-                txids_to_download,
-                chunk_size,
-                db,
-            ))?);
-            let mut prev_txids = HashSet::new();
-            let mut txids_downloaded = HashSet::new();
-            for tx in txs_downloaded.iter() {
-                txids_downloaded.insert(tx.txid());
-                // add every previous input tx, but skip coinbase
-                for input in tx.input.iter().filter(|i| !i.previous_output.is_null()) {
-                    prev_txids.insert(input.previous_output.txid);
-                }
-            }
-            let already_present: HashSet<Txid> =
-                txids_downloaded.union(&txids_raw_in_db).cloned().collect();
-            let prev_txs_to_download: Vec<&Txid> =
-                prev_txids.difference(&already_present).collect();
-            info!("{} previous txs to download", prev_txs_to_download.len());
-            txs_downloaded.extend(maybe_await!(self.download_and_save_in_chunks(
-                prev_txs_to_download,
-                chunk_size,
-                db,
-            ))?);
-        }
-
-        Ok(txs_downloaded)
-    }
-
-    /// download headers at heights in `txid_height` if tx details not already present, returns a map Txid -> timestamp
-    fn download_needed_headers(
-        &self,
-        txid_height: &HashMap<Txid, Option<u32>>,
-        txs_details_in_db: &HashMap<Txid, TransactionDetails>,
-        chunk_size: usize,
-    ) -> Result<HashMap<Txid, u64>, Error> {
-        let mut txid_timestamp = HashMap::new();
-        let needed_txid_height: HashMap<&Txid, u32> = txid_height
-            .iter()
-            .filter(|(t, _)| txs_details_in_db.get(*t).is_none())
-            .filter_map(|(t, o)| o.map(|h| (t, h)))
-            .collect();
-        let needed_heights: HashSet<u32> = needed_txid_height.values().cloned().collect();
-        if !needed_heights.is_empty() {
-            info!("{} headers to download for timestamp", needed_heights.len());
-            let mut height_timestamp: HashMap<u32, u64> = HashMap::new();
-            for chunk in ChunksIterator::new(needed_heights.into_iter(), chunk_size) {
-                let call_result: Vec<BlockHeader> =
-                    maybe_await!(self.els_batch_block_header(chunk.clone()))?;
-                height_timestamp.extend(
-                    chunk
-                        .into_iter()
-                        .zip(call_result.iter().map(|h| h.time as u64)),
-                );
-            }
-            for (txid, height) in needed_txid_height {
-                let timestamp = height_timestamp
-                    .get(&height)
-                    .ok_or_else(|| Error::Generic("timestamp missing".to_string()))?;
-                txid_timestamp.insert(*txid, *timestamp);
-            }
-        }
-
-        Ok(txid_timestamp)
-    }
-
-    fn download_and_save_in_chunks<D: BatchDatabase>(
-        &self,
-        to_download: Vec<&Txid>,
-        chunk_size: usize,
-        db: &mut D,
-    ) -> Result<Vec<Transaction>, Error> {
-        let mut txs_downloaded = vec![];
-        for chunk in ChunksIterator::new(to_download.into_iter(), chunk_size) {
-            let call_result: Vec<Transaction> =
-                maybe_await!(self.els_batch_transaction_get(chunk))?;
-            let mut batch = db.begin_batch();
-            for new_tx in call_result.iter() {
-                batch.set_raw_tx(new_tx)?;
-            }
-            db.commit_batch(batch)?;
-            txs_downloaded.extend(call_result);
-        }
-
-        Ok(txs_downloaded)
-    }
-}
-
-fn save_transaction_details_and_utxos<D: BatchDatabase>(
-    txid: &Txid,
-    db: &mut D,
-    timestamp: u64,
-    height: Option<u32>,
-    updates: &mut dyn BatchOperations,
-    utxo_deps: &HashMap<OutPoint, OutPoint>,
-) -> Result<(), Error> {
-    let tx = db.get_raw_tx(txid)?.ok_or(Error::TransactionNotFound)?;
-
-    let mut incoming: u64 = 0;
-    let mut outgoing: u64 = 0;
-
-    let mut inputs_sum: u64 = 0;
-    let mut outputs_sum: u64 = 0;
-
-    // look for our own inputs
-    for input in tx.input.iter() {
-        // skip coinbase inputs
-        if input.previous_output.is_null() {
-            continue;
-        }
-
-        // We already downloaded all previous output txs in the previous step
-        if let Some(previous_output) = db.get_previous_output(&input.previous_output)? {
-            inputs_sum += previous_output.value;
-
-            if db.is_mine(&previous_output.script_pubkey)? {
-                outgoing += previous_output.value;
-            }
-        } else {
-            // The input is not ours, but we still need to count it for the fees
-            let tx = db
-                .get_raw_tx(&input.previous_output.txid)?
-                .ok_or(Error::TransactionNotFound)?;
-            inputs_sum += tx.output[input.previous_output.vout as usize].value;
-        }
-
-        // removes conflicting UTXO if any (generated from same inputs, like for example RBF)
-        if let Some(outpoint) = utxo_deps.get(&input.previous_output) {
-            updates.del_utxo(&outpoint)?;
-        }
-    }
-
-    for (i, output) in tx.output.iter().enumerate() {
-        // to compute the fees later
-        outputs_sum += output.value;
-
-        // this output is ours, we have a path to derive it
-        if let Some((keychain, _child)) = db.get_path_from_script_pubkey(&output.script_pubkey)? {
-            debug!("{} output #{} is mine, adding utxo", txid, i);
-            updates.set_utxo(&LocalUtxo {
-                outpoint: OutPoint::new(tx.txid(), i as u32),
-                txout: output.clone(),
-                keychain,
-            })?;
-
-            incoming += output.value;
-        }
-    }
-
-    let tx_details = TransactionDetails {
-        txid: tx.txid(),
-        transaction: Some(tx),
-        received: incoming,
-        sent: outgoing,
-        height,
-        timestamp,
-        fees: inputs_sum.saturating_sub(outputs_sum), /* if the tx is a coinbase, fees would be negative */
-    };
-    updates.set_tx(&tx_details)?;
-
-    Ok(())
-}
-
-/// returns utxo dependency as the inputs needed for the utxo to exist
-/// `tx_raw_in_db` must contains utxo's generating txs or errors witt [crate::Error::TransactionNotFound]
-fn utxos_deps<D: BatchDatabase>(
-    db: &mut D,
-    tx_raw_in_db: &HashMap<Txid, Transaction>,
-) -> Result<HashMap<OutPoint, OutPoint>, Error> {
-    let utxos = db.iter_utxos()?;
-    let mut utxos_deps = HashMap::new();
-    for utxo in utxos {
-        let from_tx = tx_raw_in_db
-            .get(&utxo.outpoint.txid)
-            .ok_or(Error::TransactionNotFound)?;
-        for input in from_tx.input.iter() {
-            utxos_deps.insert(input.previous_output, utxo.outpoint);
-        }
-    }
-    Ok(utxos_deps)
-}

src/database/any.rs

@@ -23,12 +23,12 @@
 //! # use bdk::database::{AnyDatabase, MemoryDatabase};
 //! # use bdk::{Wallet};
 //! let memory = MemoryDatabase::default();
-//! let wallet_memory = Wallet::new_offline("...", None, Network::Testnet, memory)?;
+//! let wallet_memory = Wallet::new("...", None, Network::Testnet, memory)?;
 //!
 //! # #[cfg(feature = "key-value-db")]
 //! # {
 //! let sled = sled::open("my-database")?.open_tree("default_tree")?;
-//! let wallet_sled = Wallet::new_offline("...", None, Network::Testnet, sled)?;
+//! let wallet_sled = Wallet::new("...", None, Network::Testnet, sled)?;
 //! # }
 //! # Ok::<(), bdk::Error>(())
 //! ```
@@ -42,7 +42,7 @@
 //! # use bdk::{Wallet};
 //! let config = serde_json::from_str("...")?;
 //! let database = AnyDatabase::from_config(&config)?;
-//! let wallet = Wallet::new_offline("...", None, Network::Testnet, database)?;
+//! let wallet = Wallet::new("...", None, Network::Testnet, database)?;
 //! # Ok::<(), bdk::Error>(())
 //! ```
 
@@ -65,6 +65,8 @@ macro_rules! impl_inner_method {
             $enum_name::Memory(inner) => inner.$name( $($args, )* ),
             #[cfg(feature = "key-value-db")]
             $enum_name::Sled(inner) => inner.$name( $($args, )* ),
+            #[cfg(feature = "sqlite")]
+            $enum_name::Sqlite(inner) => inner.$name( $($args, )* ),
         }
     }
 }
@@ -82,10 +84,15 @@ pub enum AnyDatabase {
     #[cfg_attr(docsrs, doc(cfg(feature = "key-value-db")))]
     /// Simple key-value embedded database based on [`sled`]
     Sled(sled::Tree),
+    #[cfg(feature = "sqlite")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "sqlite")))]
+    /// Sqlite embedded database using [`rusqlite`]
+    Sqlite(sqlite::SqliteDatabase),
 }
 
 impl_from!(memory::MemoryDatabase, AnyDatabase, Memory,);
 impl_from!(sled::Tree, AnyDatabase, Sled, #[cfg(feature = "key-value-db")]);
+impl_from!(sqlite::SqliteDatabase, AnyDatabase, Sqlite, #[cfg(feature = "sqlite")]);
 
 /// Type that contains any of the [`BatchDatabase::Batch`] types defined by the library
 pub enum AnyBatch {
@@ -95,6 +102,10 @@ pub enum AnyBatch {
     #[cfg_attr(docsrs, doc(cfg(feature = "key-value-db")))]
     /// Simple key-value embedded database based on [`sled`]
     Sled(<sled::Tree as BatchDatabase>::Batch),
+    #[cfg(feature = "sqlite")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "sqlite")))]
+    /// Sqlite embedded database using [`rusqlite`]
+    Sqlite(<sqlite::SqliteDatabase as BatchDatabase>::Batch),
 }
 
 impl_from!(
@@ -103,6 +114,7 @@ impl_from!(
     Memory,
 );
 impl_from!(<sled::Tree as BatchDatabase>::Batch, AnyBatch, Sled, #[cfg(feature = "key-value-db")]);
+impl_from!(<sqlite::SqliteDatabase as BatchDatabase>::Batch, AnyBatch, Sqlite, #[cfg(feature = "sqlite")]);
 
 impl BatchOperations for AnyDatabase {
     fn set_script_pubkey(
@@ -132,6 +144,9 @@ impl BatchOperations for AnyDatabase {
     fn set_last_index(&mut self, keychain: KeychainKind, value: u32) -> Result<(), Error> {
         impl_inner_method!(AnyDatabase, self, set_last_index, keychain, value)
     }
+    fn set_sync_time(&mut self, sync_time: SyncTime) -> Result<(), Error> {
+        impl_inner_method!(AnyDatabase, self, set_sync_time, sync_time)
+    }
 
     fn del_script_pubkey_from_path(
         &mut self,
@@ -168,6 +183,9 @@ impl BatchOperations for AnyDatabase {
     fn del_last_index(&mut self, keychain: KeychainKind) -> Result<Option<u32>, Error> {
         impl_inner_method!(AnyDatabase, self, del_last_index, keychain)
     }
+    fn del_sync_time(&mut self) -> Result<Option<SyncTime>, Error> {
+        impl_inner_method!(AnyDatabase, self, del_sync_time)
+    }
 }
 
 impl Database for AnyDatabase {
@@ -229,10 +247,17 @@ impl Database for AnyDatabase {
     fn get_last_index(&self, keychain: KeychainKind) -> Result<Option<u32>, Error> {
         impl_inner_method!(AnyDatabase, self, get_last_index, keychain)
     }
+    fn get_sync_time(&self) -> Result<Option<SyncTime>, Error> {
+        impl_inner_method!(AnyDatabase, self, get_sync_time)
+    }
 
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error> {
         impl_inner_method!(AnyDatabase, self, increment_last_index, keychain)
     }
+
+    fn flush(&mut self) -> Result<(), Error> {
+        impl_inner_method!(AnyDatabase, self, flush)
+    }
 }
 
 impl BatchOperations for AnyBatch {
@@ -256,6 +281,9 @@ impl BatchOperations for AnyBatch {
     fn set_last_index(&mut self, keychain: KeychainKind, value: u32) -> Result<(), Error> {
         impl_inner_method!(AnyBatch, self, set_last_index, keychain, value)
     }
+    fn set_sync_time(&mut self, sync_time: SyncTime) -> Result<(), Error> {
+        impl_inner_method!(AnyBatch, self, set_sync_time, sync_time)
+    }
 
     fn del_script_pubkey_from_path(
         &mut self,
@@ -286,6 +314,9 @@ impl BatchOperations for AnyBatch {
     fn del_last_index(&mut self, keychain: KeychainKind) -> Result<Option<u32>, Error> {
         impl_inner_method!(AnyBatch, self, del_last_index, keychain)
     }
+    fn del_sync_time(&mut self) -> Result<Option<SyncTime>, Error> {
+        impl_inner_method!(AnyBatch, self, del_sync_time)
+    }
 }
 
 impl BatchDatabase for AnyDatabase {
@@ -296,19 +327,26 @@ impl BatchDatabase for AnyDatabase {
             AnyDatabase::Memory(inner) => inner.begin_batch().into(),
             #[cfg(feature = "key-value-db")]
             AnyDatabase::Sled(inner) => inner.begin_batch().into(),
+            #[cfg(feature = "sqlite")]
+            AnyDatabase::Sqlite(inner) => inner.begin_batch().into(),
         }
     }
     fn commit_batch(&mut self, batch: Self::Batch) -> Result<(), Error> {
         match self {
             AnyDatabase::Memory(db) => match batch {
                 AnyBatch::Memory(batch) => db.commit_batch(batch),
-                #[cfg(feature = "key-value-db")]
-                _ => unimplemented!("Sled batch shouldn't be used with Memory db."),
+                #[cfg(any(feature = "key-value-db", feature = "sqlite"))]
+                _ => unimplemented!("Other batch shouldn't be used with Memory db."),
             },
             #[cfg(feature = "key-value-db")]
             AnyDatabase::Sled(db) => match batch {
                 AnyBatch::Sled(batch) => db.commit_batch(batch),
-                _ => unimplemented!("Memory batch shouldn't be used with Sled db."),
+                _ => unimplemented!("Other batch shouldn't be used with Sled db."),
+            },
+            #[cfg(feature = "sqlite")]
+            AnyDatabase::Sqlite(db) => match batch {
+                AnyBatch::Sqlite(batch) => db.commit_batch(batch),
+                _ => unimplemented!("Other batch shouldn't be used with Sqlite db."),
             },
         }
     }
@@ -333,6 +371,23 @@ impl ConfigurableDatabase for sled::Tree {
     }
 }
 
+/// Configuration type for a [`sqlite::SqliteDatabase`] database
+#[cfg(feature = "sqlite")]
+#[derive(Debug, serde::Serialize, serde::Deserialize)]
+pub struct SqliteDbConfiguration {
+    /// Main directory of the db
+    pub path: String,
+}
+
+#[cfg(feature = "sqlite")]
+impl ConfigurableDatabase for sqlite::SqliteDatabase {
+    type Config = SqliteDbConfiguration;
+
+    fn from_config(config: &Self::Config) -> Result<Self, Error> {
+        Ok(sqlite::SqliteDatabase::new(config.path.clone()))
+    }
+}
+
 /// Type that can contain any of the database configurations defined by the library
 ///
 /// This allows storing a single configuration that can be loaded into an [`AnyDatabase`]
@@ -346,6 +401,10 @@ pub enum AnyDatabaseConfig {
     #[cfg_attr(docsrs, doc(cfg(feature = "key-value-db")))]
     /// Simple key-value embedded database based on [`sled`]
     Sled(SledDbConfiguration),
+    #[cfg(feature = "sqlite")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "sqlite")))]
+    /// Sqlite embedded database using [`rusqlite`]
+    Sqlite(SqliteDbConfiguration),
 }
 
 impl ConfigurableDatabase for AnyDatabase {
@@ -358,9 +417,14 @@ impl ConfigurableDatabase for AnyDatabase {
             }
             #[cfg(feature = "key-value-db")]
             AnyDatabaseConfig::Sled(inner) => AnyDatabase::Sled(sled::Tree::from_config(inner)?),
+            #[cfg(feature = "sqlite")]
+            AnyDatabaseConfig::Sqlite(inner) => {
+                AnyDatabase::Sqlite(sqlite::SqliteDatabase::from_config(inner)?)
+            }
         })
     }
 }
 
 impl_from!((), AnyDatabaseConfig, Memory,);
 impl_from!(SledDbConfiguration, AnyDatabaseConfig, Sled, #[cfg(feature = "key-value-db")]);
+impl_from!(SqliteDbConfiguration, AnyDatabaseConfig, Sqlite, #[cfg(feature = "sqlite")]);

src/database/keyvalue.rs

@@ -18,7 +18,7 @@ use bitcoin::hash_types::Txid;
 use bitcoin::{OutPoint, Script, Transaction};
 
 use crate::database::memory::MapKey;
-use crate::database::{BatchDatabase, BatchOperations, Database};
+use crate::database::{BatchDatabase, BatchOperations, Database, SyncTime};
 use crate::error::Error;
 use crate::types::*;
 
@@ -82,6 +82,13 @@ macro_rules! impl_batch_operations {
             Ok(())
         }
 
+        fn set_sync_time(&mut self, data: SyncTime) -> Result<(), Error> {
+            let key = MapKey::SyncTime.as_map_key();
+            self.insert(key, serde_json::to_vec(&data)?)$($after_insert)*;
+
+            Ok(())
+        }
+
         fn del_script_pubkey_from_path(&mut self, keychain: KeychainKind, path: u32) -> Result<Option<Script>, Error> {
             let key = MapKey::Path((Some(keychain), Some(path))).as_map_key();
             let res = self.remove(key);
@@ -168,6 +175,14 @@ macro_rules! impl_batch_operations {
                 }
             }
         }
+
+        fn del_sync_time(&mut self) -> Result<Option<SyncTime>, Error> {
+            let key = MapKey::SyncTime.as_map_key();
+            let res = self.remove(key);
+            let res = $process_delete!(res);
+
+            Ok(res.map(|b| serde_json::from_slice(&b)).transpose()?)
+        }
     }
 }
 
@@ -320,7 +335,7 @@ impl Database for Tree {
             .map(|b| -> Result<_, Error> {
                 let mut txdetails: TransactionDetails = serde_json::from_slice(&b)?;
                 if include_raw {
-                    txdetails.transaction = self.get_raw_tx(&txid)?;
+                    txdetails.transaction = self.get_raw_tx(txid)?;
                 }
 
                 Ok(txdetails)
@@ -342,6 +357,14 @@ impl Database for Tree {
             .transpose()
     }
 
+    fn get_sync_time(&self) -> Result<Option<SyncTime>, Error> {
+        let key = MapKey::SyncTime.as_map_key();
+        Ok(self
+            .get(key)?
+            .map(|b| serde_json::from_slice(&b))
+            .transpose()?)
+    }
+
     // inserts 0 if not present
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error> {
         let key = MapKey::LastIndex(keychain).as_map_key();
@@ -367,6 +390,10 @@ impl Database for Tree {
             Ok(val)
         })
     }
+
+    fn flush(&mut self) -> Result<(), Error> {
+        Ok(Tree::flush(self).map(|_| ())?)
+    }
 }
 
 impl BatchDatabase for Tree {
@@ -383,6 +410,7 @@ impl BatchDatabase for Tree {
 
 #[cfg(test)]
 mod test {
+    use lazy_static::lazy_static;
     use std::sync::{Arc, Condvar, Mutex, Once};
     use std::time::{SystemTime, UNIX_EPOCH};
 
@@ -465,4 +493,9 @@ mod test {
     fn test_last_index() {
         crate::database::test::test_last_index(get_tree());
     }
+
+    #[test]
+    fn test_sync_time() {
+        crate::database::test::test_sync_time(get_tree());
+    }
 }

src/database/memory.rs

@@ -14,6 +14,7 @@
 //! This module defines an in-memory database type called [`MemoryDatabase`] that is based on a
 //! [`BTreeMap`].
 
+use std::any::Any;
 use std::collections::BTreeMap;
 use std::ops::Bound::{Excluded, Included};
 
@@ -21,7 +22,7 @@ use bitcoin::consensus::encode::{deserialize, serialize};
 use bitcoin::hash_types::Txid;
 use bitcoin::{OutPoint, Script, Transaction};
 
-use crate::database::{BatchDatabase, BatchOperations, ConfigurableDatabase, Database};
+use crate::database::{BatchDatabase, BatchOperations, ConfigurableDatabase, Database, SyncTime};
 use crate::error::Error;
 use crate::types::*;
 
@@ -32,6 +33,7 @@ use crate::types::*;
 // transactions         t<txid> -> tx details
 // deriv indexes        c{i,e} -> u32
 // descriptor checksum  d{i,e} -> vec<u8>
+// last sync time       l -> { height, timestamp }
 
 pub(crate) enum MapKey<'a> {
     Path((Option<KeychainKind>, Option<u32>)),
@@ -40,6 +42,7 @@ pub(crate) enum MapKey<'a> {
     RawTx(Option<&'a Txid>),
     Transaction(Option<&'a Txid>),
     LastIndex(KeychainKind),
+    SyncTime,
     DescriptorChecksum(KeychainKind),
 }
 
@@ -58,6 +61,7 @@ impl MapKey<'_> {
             MapKey::RawTx(_) => b"r".to_vec(),
             MapKey::Transaction(_) => b"t".to_vec(),
             MapKey::LastIndex(st) => [b"c", st.as_ref()].concat(),
+            MapKey::SyncTime => b"l".to_vec(),
             MapKey::DescriptorChecksum(st) => [b"d", st.as_ref()].concat(),
         }
     }
@@ -105,12 +109,12 @@ fn after(key: &[u8]) -> Vec<u8> {
 /// Once it's dropped its content will be lost.
 ///
 /// If you are looking for a permanent storage solution, you can try with the default key-value
-/// database called [`sled`]. See the [`database`] module documentation for more defailts.
+/// database called [`sled`]. See the [`database`] module documentation for more details.
 ///
 /// [`database`]: crate::database
 #[derive(Debug, Default)]
 pub struct MemoryDatabase {
-    map: BTreeMap<Vec<u8>, Box<dyn std::any::Any>>,
+    map: BTreeMap<Vec<u8>, Box<dyn Any + Send + Sync>>,
     deleted_keys: Vec<Vec<u8>>,
 }
 
@@ -179,6 +183,12 @@ impl BatchOperations for MemoryDatabase {
 
         Ok(())
     }
+    fn set_sync_time(&mut self, data: SyncTime) -> Result<(), Error> {
+        let key = MapKey::SyncTime.as_map_key();
+        self.map.insert(key, Box::new(data));
+
+        Ok(())
+    }
 
     fn del_script_pubkey_from_path(
         &mut self,
@@ -269,6 +279,13 @@ impl BatchOperations for MemoryDatabase {
             Some(b) => Ok(Some(*b.downcast_ref().unwrap())),
         }
     }
+    fn del_sync_time(&mut self) -> Result<Option<SyncTime>, Error> {
+        let key = MapKey::SyncTime.as_map_key();
+        let res = self.map.remove(&key);
+        self.deleted_keys.push(key);
+
+        Ok(res.map(|b| b.downcast_ref().cloned().unwrap()))
+    }
 }
 
 impl Database for MemoryDatabase {
@@ -394,7 +411,7 @@ impl Database for MemoryDatabase {
         Ok(self.map.get(&key).map(|b| {
             let mut txdetails: TransactionDetails = b.downcast_ref().cloned().unwrap();
             if include_raw {
-                txdetails.transaction = self.get_raw_tx(&txid).unwrap();
+                txdetails.transaction = self.get_raw_tx(txid).unwrap();
             }
 
             txdetails
@@ -406,6 +423,14 @@ impl Database for MemoryDatabase {
         Ok(self.map.get(&key).map(|b| *b.downcast_ref().unwrap()))
     }
 
+    fn get_sync_time(&self) -> Result<Option<SyncTime>, Error> {
+        let key = MapKey::SyncTime.as_map_key();
+        Ok(self
+            .map
+            .get(&key)
+            .map(|b| b.downcast_ref().cloned().unwrap()))
+    }
+
     // inserts 0 if not present
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error> {
         let key = MapKey::LastIndex(keychain).as_map_key();
@@ -419,6 +444,10 @@ impl Database for MemoryDatabase {
 
         Ok(*value)
     }
+
+    fn flush(&mut self) -> Result<(), Error> {
+        Ok(())
+    }
 }
 
 impl BatchDatabase for MemoryDatabase {
@@ -429,8 +458,8 @@ impl BatchDatabase for MemoryDatabase {
     }
 
     fn commit_batch(&mut self, mut batch: Self::Batch) -> Result<(), Error> {
-        for key in batch.deleted_keys {
-            self.map.remove(&key);
+        for key in batch.deleted_keys.iter() {
+            self.map.remove(key);
         }
         self.map.append(&mut batch.map);
         Ok(())
@@ -452,20 +481,21 @@ impl ConfigurableDatabase for MemoryDatabase {
 /// don't have `test` set.
 macro_rules! populate_test_db {
     ($db:expr, $tx_meta:expr, $current_height:expr$(,)?) => {{
+        use std::str::FromStr;
         use $crate::database::BatchOperations;
         let mut db = $db;
         let tx_meta = $tx_meta;
         let current_height: Option<u32> = $current_height;
-        let tx = Transaction {
+        let tx = $crate::bitcoin::Transaction {
             version: 1,
             lock_time: 0,
             input: vec![],
             output: tx_meta
                 .output
                 .iter()
-                .map(|out_meta| bitcoin::TxOut {
+                .map(|out_meta| $crate::bitcoin::TxOut {
                     value: out_meta.value,
-                    script_pubkey: bitcoin::Address::from_str(&out_meta.to_address)
+                    script_pubkey: $crate::bitcoin::Address::from_str(&out_meta.to_address)
                         .unwrap()
                         .script_pubkey(),
                 })
@@ -473,29 +503,30 @@ macro_rules! populate_test_db {
         };
 
         let txid = tx.txid();
-        let height = tx_meta
-            .min_confirmations
-            .map(|conf| current_height.unwrap().checked_sub(conf as u32).unwrap());
+        let confirmation_time = tx_meta.min_confirmations.map(|conf| $crate::BlockTime {
+            height: current_height.unwrap().checked_sub(conf as u32).unwrap(),
+            timestamp: 0,
+        });
 
-        let tx_details = TransactionDetails {
+        let tx_details = $crate::TransactionDetails {
             transaction: Some(tx.clone()),
             txid,
-            timestamp: 0,
-            height,
+            fee: Some(0),
             received: 0,
             sent: 0,
-            fees: 0,
+            confirmation_time,
+            verified: current_height.is_some(),
         };
 
         db.set_tx(&tx_details).unwrap();
         for (vout, out) in tx.output.iter().enumerate() {
-            db.set_utxo(&LocalUtxo {
+            db.set_utxo(&$crate::LocalUtxo {
                 txout: out.clone(),
-                outpoint: OutPoint {
+                outpoint: $crate::bitcoin::OutPoint {
                     txid,
                     vout: vout as u32,
                 },
-                keychain: KeychainKind::External,
+                keychain: $crate::KeychainKind::External,
             })
             .unwrap();
         }
@@ -524,7 +555,7 @@ macro_rules! doctest_wallet {
             Some(100),
         );
 
-        $crate::Wallet::new_offline(
+        $crate::Wallet::new(
             &descriptors.0,
             descriptors.1.as_ref(),
             Network::Regtest,
@@ -581,4 +612,9 @@ mod test {
     fn test_last_index() {
         crate::database::test::test_last_index(get_tree());
     }
+
+    #[test]
+    fn test_sync_time() {
+        crate::database::test::test_sync_time(get_tree());
+    }
 }

src/database/mod.rs

@@ -24,6 +24,8 @@
 //!
 //! [`Wallet`]: crate::wallet::Wallet
 
+use serde::{Deserialize, Serialize};
+
 use bitcoin::hash_types::Txid;
 use bitcoin::{OutPoint, Script, Transaction, TxOut};
 
@@ -36,9 +38,23 @@ pub use any::{AnyDatabase, AnyDatabaseConfig};
 #[cfg(feature = "key-value-db")]
 pub(crate) mod keyvalue;
 
+#[cfg(feature = "sqlite")]
+pub(crate) mod sqlite;
+#[cfg(feature = "sqlite")]
+pub use sqlite::SqliteDatabase;
+
 pub mod memory;
 pub use memory::MemoryDatabase;
 
+/// Blockchain state at the time of syncing
+///
+/// Contains only the block time and height at the moment
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct SyncTime {
+    /// Block timestamp and height at the time of sync
+    pub block_time: BlockTime,
+}
+
 /// Trait for operations that can be batched
 ///
 /// This trait defines the list of operations that must be implemented on the [`Database`] type and
@@ -59,6 +75,8 @@ pub trait BatchOperations {
     fn set_tx(&mut self, transaction: &TransactionDetails) -> Result<(), Error>;
     /// Store the last derivation index for a given keychain.
     fn set_last_index(&mut self, keychain: KeychainKind, value: u32) -> Result<(), Error>;
+    /// Store the sync time
+    fn set_sync_time(&mut self, sync_time: SyncTime) -> Result<(), Error>;
 
     /// Delete a script_pubkey given the keychain and its child number.
     fn del_script_pubkey_from_path(
@@ -84,6 +102,10 @@ pub trait BatchOperations {
     ) -> Result<Option<TransactionDetails>, Error>;
     /// Delete the last derivation index for a keychain.
     fn del_last_index(&mut self, keychain: KeychainKind) -> Result<Option<u32>, Error>;
+    /// Reset the sync time to `None`
+    ///
+    /// Returns the removed value
+    fn del_sync_time(&mut self) -> Result<Option<SyncTime>, Error>;
 }
 
 /// Trait for reading data from a database
@@ -127,13 +149,18 @@ pub trait Database: BatchOperations {
     fn get_raw_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error>;
     /// Fetch the transaction metadata and optionally also the raw transaction
     fn get_tx(&self, txid: &Txid, include_raw: bool) -> Result<Option<TransactionDetails>, Error>;
-    /// Return the last defivation index for a keychain.
+    /// Return the last derivation index for a keychain.
     fn get_last_index(&self, keychain: KeychainKind) -> Result<Option<u32>, Error>;
+    /// Return the sync time, if present
+    fn get_sync_time(&self) -> Result<Option<SyncTime>, Error>;
 
     /// Increment the last derivation index for a keychain and return it
     ///
     /// It should insert and return `0` if not present in the database
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error>;
+
+    /// Force changes to be written to disk
+    fn flush(&mut self) -> Result<(), Error>;
 }
 
 /// Trait for a database that supports batch operations
@@ -314,11 +341,14 @@ pub mod test {
         let mut tx_details = TransactionDetails {
             transaction: Some(tx),
             txid,
-            timestamp: 123456,
             received: 1337,
             sent: 420420,
-            fees: 140,
-            height: Some(1000),
+            fee: Some(140),
+            confirmation_time: Some(BlockTime {
+                timestamp: 123456,
+                height: 1000,
+            }),
+            verified: true,
         };
 
         tree.set_tx(&tx_details).unwrap();
@@ -366,5 +396,25 @@ pub mod test {
         );
     }
 
+    pub fn test_sync_time<D: Database>(mut tree: D) {
+        assert!(tree.get_sync_time().unwrap().is_none());
+
+        tree.set_sync_time(SyncTime {
+            block_time: BlockTime {
+                height: 100,
+                timestamp: 1000,
+            },
+        })
+        .unwrap();
+
+        let extracted = tree.get_sync_time().unwrap();
+        assert!(extracted.is_some());
+        assert_eq!(extracted.as_ref().unwrap().block_time.height, 100);
+        assert_eq!(extracted.as_ref().unwrap().block_time.timestamp, 1000);
+
+        tree.del_sync_time().unwrap();
+        assert!(tree.get_sync_time().unwrap().is_none());
+    }
+
     // TODO: more tests...
 }

src/descriptor/dsl.rs

@@ -84,7 +84,7 @@ macro_rules! impl_leaf_opcode {
         )
         .map_err($crate::descriptor::DescriptorError::Miniscript)
         .and_then(|minisc| {
-            minisc.check_minsicript()?;
+            minisc.check_miniscript()?;
             Ok(minisc)
         })
         .map(|minisc| {
@@ -108,7 +108,7 @@ macro_rules! impl_leaf_opcode_value {
         )
         .map_err($crate::descriptor::DescriptorError::Miniscript)
         .and_then(|minisc| {
-            minisc.check_minsicript()?;
+            minisc.check_miniscript()?;
             Ok(minisc)
         })
         .map(|minisc| {
@@ -132,7 +132,7 @@ macro_rules! impl_leaf_opcode_value_two {
         )
         .map_err($crate::descriptor::DescriptorError::Miniscript)
         .and_then(|minisc| {
-            minisc.check_minsicript()?;
+            minisc.check_miniscript()?;
             Ok(minisc)
         })
         .map(|minisc| {
@@ -165,7 +165,7 @@ macro_rules! impl_node_opcode_two {
                     std::sync::Arc::new(b_minisc),
                 ))?;
 
-                minisc.check_minsicript()?;
+                minisc.check_miniscript()?;
 
                 Ok((minisc, a_keymap, $crate::keys::merge_networks(&a_networks, &b_networks)))
             })
@@ -175,7 +175,7 @@ macro_rules! impl_node_opcode_two {
 #[doc(hidden)]
 #[macro_export]
 macro_rules! impl_node_opcode_three {
-    ( $terminal_variant:ident, $( $inner:tt )* ) => {
+    ( $terminal_variant:ident, $( $inner:tt )* ) => ({
         use $crate::descriptor::CheckMiniscript;
 
         let inner = $crate::fragment_internal!( @t $( $inner )* );
@@ -197,11 +197,11 @@ macro_rules! impl_node_opcode_three {
                     std::sync::Arc::new(c_minisc),
                 ))?;
 
-                minisc.check_minsicript()?;
+                minisc.check_miniscript()?;
 
                 Ok((minisc, a_keymap, networks))
             })
-    };
+    });
 }
 
 #[doc(hidden)]
@@ -243,7 +243,7 @@ macro_rules! apply_modifier {
                     ),
                 )?;
 
-                minisc.check_minsicript()?;
+                minisc.check_miniscript()?;
 
                 Ok((minisc, keymap, networks))
             })
@@ -521,7 +521,7 @@ macro_rules! fragment_internal {
     // three operands it's (X, (X, (X, ()))), etc.
     //
     // To check that the right number of arguments has been passed we can "cast" those tuples to
-    // more convenient structures like `TupleTwo`. If the conversion succedes, the right number of
+    // more convenient structures like `TupleTwo`. If the conversion succeeds, the right number of
     // args was passed. Otherwise the compilation fails entirely.
     ( @t $op:ident ( $( $args:tt )* ) $( $tail:tt )* ) => ({
         ($crate::fragment!( $op ( $( $args )* ) ), $crate::fragment_internal!( @t $( $tail )* ))
@@ -571,8 +571,9 @@ macro_rules! fragment {
     ( pk ( $key:expr ) ) => ({
         $crate::fragment!(c:pk_k ( $key ))
     });
-    ( pk_h ( $key_hash:expr ) ) => ({
-        $crate::impl_leaf_opcode_value!(PkH, $key_hash)
+    ( pk_h ( $key:expr ) ) => ({
+        let secp = $crate::bitcoin::secp256k1::Secp256k1::new();
+        $crate::keys::make_pkh($key, &secp)
     });
     ( after ( $value:expr ) ) => ({
         $crate::impl_leaf_opcode_value!(After, $value)
@@ -601,6 +602,9 @@ macro_rules! fragment {
     ( and_or ( $( $inner:tt )* ) ) => ({
         $crate::impl_node_opcode_three!(AndOr, $( $inner )*)
     });
+    ( andor ( $( $inner:tt )* ) ) => ({
+        $crate::impl_node_opcode_three!(AndOr, $( $inner )*)
+    });
     ( or_b ( $( $inner:tt )* ) ) => ({
         $crate::impl_node_opcode_two!(OrB, $( $inner )*)
     });
@@ -790,6 +794,25 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_fixed_threeop_descriptors() {
+        let redeem_key = bitcoin::PublicKey::from_str(
+            "03a34b99f22c790c4e36b2b3c2c35a36db06226e41c692fc82b8b56ac1c540c5bd",
+        )
+        .unwrap();
+        let move_key = bitcoin::PublicKey::from_str(
+            "032e58afe51f9ed8ad3cc7897f634d881fdbe49a81564629ded8156bebd2ffd1af",
+        )
+        .unwrap();
+
+        check(
+            descriptor!(sh(wsh(and_or(pk(redeem_key), older(1000), pk(move_key))))),
+            true,
+            true,
+            &["2MypGwr5eQWAWWJtiJgUEToVxc4zuokjQRe"],
+        );
+    }
+
     #[test]
     fn test_bip32_legacy_descriptors() {
         let xprv = bip32::ExtendedPrivKey::from_str("tprv8ZgxMBicQKsPcx5nBGsR63Pe8KnRUqmbJNENAfGftF3yuXoMMoVJJcYeUw5eVkm9WBPjWYt6HMWYJNesB5HaNVBaFc1M6dRjWSYnmewUMYy").unwrap();

src/descriptor/mod.rs

@@ -128,11 +128,11 @@ impl IntoWalletDescriptor for (ExtendedDescriptor, KeyMap) {
             let (pk, _, networks) = if self.0.is_witness() {
                 let desciptor_key: DescriptorKey<miniscript::Segwitv0> =
                     pk.clone().into_descriptor_key()?;
-                desciptor_key.extract(&secp)?
+                desciptor_key.extract(secp)?
             } else {
                 let desciptor_key: DescriptorKey<miniscript::Legacy> =
                     pk.clone().into_descriptor_key()?;
-                desciptor_key.extract(&secp)?
+                desciptor_key.extract(secp)?
             };
 
             if networks.contains(&network) {
@@ -238,13 +238,13 @@ pub(crate) fn into_wallet_descriptor_checked<T: IntoWalletDescriptor>(
 #[doc(hidden)]
 /// Used internally mainly by the `descriptor!()` and `fragment!()` macros
 pub trait CheckMiniscript<Ctx: miniscript::ScriptContext> {
-    fn check_minsicript(&self) -> Result<(), miniscript::Error>;
+    fn check_miniscript(&self) -> Result<(), miniscript::Error>;
 }
 
 impl<Ctx: miniscript::ScriptContext, Pk: miniscript::MiniscriptKey> CheckMiniscript<Ctx>
     for miniscript::Miniscript<Pk, Ctx>
 {
-    fn check_minsicript(&self) -> Result<(), miniscript::Error> {
+    fn check_miniscript(&self) -> Result<(), miniscript::Error> {
         Ctx::check_global_validity(self)?;
 
         Ok(())
@@ -667,7 +667,7 @@ mod test {
 
         // make a descriptor out of it
         let desc = crate::descriptor!(wpkh(key)).unwrap();
-        // this should conver the key that supports "any_network" to the right network (testnet)
+        // this should convert the key that supports "any_network" to the right network (testnet)
         let (wallet_desc, _) = desc
             .into_wallet_descriptor(&secp, Network::Testnet)
             .unwrap();

src/descriptor/policy.rs

@@ -47,14 +47,12 @@ use bitcoin::util::bip32::Fingerprint;
 use bitcoin::PublicKey;
 
 use miniscript::descriptor::{DescriptorPublicKey, ShInner, SortedMultiVec, WshInner};
-use miniscript::{
-    Descriptor, Miniscript, MiniscriptKey, Satisfier, ScriptContext, Terminal, ToPublicKey,
-};
+use miniscript::{Descriptor, Miniscript, MiniscriptKey, Satisfier, ScriptContext, Terminal};
 
 #[allow(unused_imports)]
 use log::{debug, error, info, trace};
 
-use crate::descriptor::{DerivedDescriptorKey, ExtractPolicy};
+use crate::descriptor::ExtractPolicy;
 use crate::wallet::signer::{SignerId, SignersContainer};
 use crate::wallet::utils::{self, After, Older, SecpCtx};
 
@@ -88,13 +86,6 @@ impl PkOrF {
             },
         }
     }
-
-    fn from_key_hash(k: hash160::Hash) -> Self {
-        PkOrF {
-            pubkey_hash: Some(k),
-            ..Default::default()
-        }
-    }
 }
 
 /// An item that needs to be satisfied
@@ -336,7 +327,7 @@ impl Satisfaction {
                         items.push(inner_index);
                         let conditions_set = other_conditions
                             .values()
-                            .fold(HashSet::new(), |set, i| set.union(&i).cloned().collect());
+                            .fold(HashSet::new(), |set, i| set.union(i).cloned().collect());
                         conditions.insert(inner_index, conditions_set);
                     }
                 }
@@ -363,9 +354,9 @@ impl Satisfaction {
                 indexes
                     .into_iter()
                     // .inspect(|x| println!("--- orig --- {:?}", x))
-                    // we map each of the combinations of elements into a tuple of ([choosen items], [conditions]). unfortunately, those items have potentially more than one
+                    // we map each of the combinations of elements into a tuple of ([chosen items], [conditions]). unfortunately, those items have potentially more than one
                     // condition (think about ORs), so we also use `mix` to expand those, i.e. [[0], [1, 2]] becomes [[0, 1], [0, 2]]. This is necessary to make sure that we
-                    // consider every possibile options and check whether or not they are compatible.
+                    // consider every possible options and check whether or not they are compatible.
                     .map(|i_vec| {
                         mix(i_vec
                             .iter()
@@ -779,25 +770,6 @@ fn signature_in_psbt(psbt: &Psbt, key: &DescriptorPublicKey, secp: &SecpCtx) ->
     })
 }
 
-fn signature_key(
-    key: &<DescriptorPublicKey as MiniscriptKey>::Hash,
-    signers: &SignersContainer,
-    secp: &SecpCtx,
-) -> Policy {
-    let key_hash = DerivedDescriptorKey::new(key.clone(), secp)
-        .to_public_key()
-        .to_pubkeyhash();
-    let mut policy: Policy = SatisfiableItem::Signature(PkOrF::from_key_hash(key_hash)).into();
-
-    if signers.find(SignerId::PkHash(key_hash)).is_some() {
-        policy.contribution = Satisfaction::Complete {
-            condition: Default::default(),
-        }
-    }
-
-    policy
-}
-
 impl<Ctx: ScriptContext> ExtractPolicy for Miniscript<DescriptorPublicKey, Ctx> {
     fn extract_policy(
         &self,
@@ -809,7 +781,7 @@ impl<Ctx: ScriptContext> ExtractPolicy for Miniscript<DescriptorPublicKey, Ctx>
             // Leaves
             Terminal::True | Terminal::False => None,
             Terminal::PkK(pubkey) => Some(signature(pubkey, signers, build_sat, secp)),
-            Terminal::PkH(pubkey_hash) => Some(signature_key(pubkey_hash, signers, secp)),
+            Terminal::PkH(pubkey_hash) => Some(signature(pubkey_hash, signers, build_sat, secp)),
             Terminal::After(value) => {
                 let mut policy: Policy = SatisfiableItem::AbsoluteTimelock { value: *value }.into();
                 policy.contribution = Satisfaction::Complete {
@@ -1007,7 +979,6 @@ mod test {
     use crate::descriptor::{ExtractPolicy, IntoWalletDescriptor};
 
     use super::*;
-    use crate::bitcoin::consensus::deserialize;
     use crate::descriptor::derived::AsDerived;
     use crate::descriptor::policy::SatisfiableItem::{Multisig, Signature, Thresh};
     use crate::keys::{DescriptorKey, IntoDescriptorKey};
@@ -1031,8 +1002,8 @@ mod test {
     ) -> (DescriptorKey<Ctx>, DescriptorKey<Ctx>, Fingerprint) {
         let path = bip32::DerivationPath::from_str(path).unwrap();
         let tprv = bip32::ExtendedPrivKey::from_str(tprv).unwrap();
-        let tpub = bip32::ExtendedPubKey::from_private(&secp, &tprv);
-        let fingerprint = tprv.fingerprint(&secp);
+        let tpub = bip32::ExtendedPubKey::from_private(secp, &tprv);
+        let fingerprint = tprv.fingerprint(secp);
         let prvkey = (tprv, path.clone()).into_descriptor_key().unwrap();
         let pubkey = (tpub, path).into_descriptor_key().unwrap();
 
@@ -1445,6 +1416,7 @@ mod test {
 
     const ALICE_TPRV_STR:&str = "tprv8ZgxMBicQKsPf6T5X327efHnvJDr45Xnb8W4JifNWtEoqXu9MRYS4v1oYe6DFcMVETxy5w3bqpubYRqvcVTqovG1LifFcVUuJcbwJwrhYzP";
     const BOB_TPRV_STR:&str = "tprv8ZgxMBicQKsPeinZ155cJAn117KYhbaN6MV3WeG6sWhxWzcvX1eg1awd4C9GpUN1ncLEM2rzEvunAg3GizdZD4QPPCkisTz99tXXB4wZArp";
+    const CAROL_TPRV_STR:&str = "tprv8ZgxMBicQKsPdC3CicFifuLCEyVVdXVUNYorxUWj3iGZ6nimnLAYAY9SYB7ib8rKzRxrCKFcEytCt6szwd2GHnGPRCBLAEAoSVDefSNk4Bt";
     const ALICE_BOB_PATH: &str = "m/0'";
 
     #[test]
@@ -1475,7 +1447,7 @@ mod test {
 
         let signers_container = Arc::new(SignersContainer::from(keymap));
 
-        let psbt: Psbt = deserialize(&base64::decode(ALICE_SIGNED_PSBT).unwrap()).unwrap();
+        let psbt = Psbt::from_str(ALICE_SIGNED_PSBT).unwrap();
 
         let policy_alice_psbt = wallet_desc
             .extract_policy(&signers_container, BuildSatisfaction::Psbt(&psbt), &secp)
@@ -1490,7 +1462,7 @@ mod test {
             )
         );
 
-        let psbt: Psbt = deserialize(&base64::decode(BOB_SIGNED_PSBT).unwrap()).unwrap();
+        let psbt = Psbt::from_str(BOB_SIGNED_PSBT).unwrap();
         let policy_bob_psbt = wallet_desc
             .extract_policy(&signers_container, BuildSatisfaction::Psbt(&psbt), &secp)
             .unwrap()
@@ -1504,7 +1476,7 @@ mod test {
             )
         );
 
-        let psbt: Psbt = deserialize(&base64::decode(ALICE_BOB_SIGNED_PSBT).unwrap()).unwrap();
+        let psbt = Psbt::from_str(ALICE_BOB_SIGNED_PSBT).unwrap();
         let policy_alice_bob_psbt = wallet_desc
             .extract_policy(&signers_container, BuildSatisfaction::Psbt(&psbt), &secp)
             .unwrap()
@@ -1545,8 +1517,7 @@ mod test {
             addr.to_string()
         );
 
-        let psbt: Psbt =
-            deserialize(&base64::decode(PSBT_POLICY_CONSIDER_TIMELOCK_EXPIRED).unwrap()).unwrap();
+        let psbt = Psbt::from_str(PSBT_POLICY_CONSIDER_TIMELOCK_EXPIRED).unwrap();
 
         let build_sat = BuildSatisfaction::PsbtTimelocks {
             psbt: &psbt,
@@ -1584,9 +1555,7 @@ mod test {
         );
         //println!("{}", serde_json::to_string(&policy_expired).unwrap());
 
-        let psbt_signed: Psbt =
-            deserialize(&base64::decode(PSBT_POLICY_CONSIDER_TIMELOCK_EXPIRED_SIGNED).unwrap())
-                .unwrap();
+        let psbt_signed = Psbt::from_str(PSBT_POLICY_CONSIDER_TIMELOCK_EXPIRED_SIGNED).unwrap();
 
         let build_sat_expired_signed = BuildSatisfaction::PsbtTimelocks {
             psbt: &psbt_signed,
@@ -1606,4 +1575,28 @@ mod test {
         );
         //println!("{}", serde_json::to_string(&policy_expired_signed).unwrap());
     }
+
+    #[test]
+    fn test_extract_pkh() {
+        let secp = Secp256k1::new();
+
+        let (prvkey_alice, _, _) = setup_keys(ALICE_TPRV_STR, ALICE_BOB_PATH, &secp);
+        let (prvkey_bob, _, _) = setup_keys(BOB_TPRV_STR, ALICE_BOB_PATH, &secp);
+        let (prvkey_carol, _, _) = setup_keys(CAROL_TPRV_STR, ALICE_BOB_PATH, &secp);
+
+        let desc = descriptor!(wsh(c: andor(
+            pk(prvkey_alice),
+            pk_k(prvkey_bob),
+            pk_h(prvkey_carol),
+        )))
+        .unwrap();
+
+        let (wallet_desc, keymap) = desc
+            .into_wallet_descriptor(&secp, Network::Testnet)
+            .unwrap();
+        let signers_container = Arc::new(SignersContainer::from(keymap));
+
+        let policy = wallet_desc.extract_policy(&signers_container, BuildSatisfaction::None, &secp);
+        assert!(policy.is_ok());
+    }
 }

src/descriptor/template.rs

@@ -79,7 +79,7 @@ impl<T: DescriptorTemplate> IntoWalletDescriptor for T {
 ///
 /// let key =
 ///     bitcoin::PrivateKey::from_wif("cTc4vURSzdx6QE6KVynWGomDbLaA75dNALMNyfjh3p8DRRar84Um")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     P2Pkh(key),
 ///     None,
 ///     Network::Testnet,
@@ -113,7 +113,7 @@ impl<K: IntoDescriptorKey<Legacy>> DescriptorTemplate for P2Pkh<K> {
 ///
 /// let key =
 ///     bitcoin::PrivateKey::from_wif("cTc4vURSzdx6QE6KVynWGomDbLaA75dNALMNyfjh3p8DRRar84Um")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     P2Wpkh_P2Sh(key),
 ///     None,
 ///     Network::Testnet,
@@ -148,7 +148,7 @@ impl<K: IntoDescriptorKey<Segwitv0>> DescriptorTemplate for P2Wpkh_P2Sh<K> {
 ///
 /// let key =
 ///     bitcoin::PrivateKey::from_wif("cTc4vURSzdx6QE6KVynWGomDbLaA75dNALMNyfjh3p8DRRar84Um")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     P2Wpkh(key),
 ///     None,
 ///     Network::Testnet,
@@ -186,7 +186,7 @@ impl<K: IntoDescriptorKey<Segwitv0>> DescriptorTemplate for P2Wpkh<K> {
 /// use bdk::template::Bip44;
 ///
 /// let key = bitcoin::util::bip32::ExtendedPrivKey::from_str("tprv8ZgxMBicQKsPeZRHk4rTG6orPS2CRNFX3njhUXx5vj9qGog5ZMH4uGReDWN5kCkY3jmWEtWause41CDvBRXD1shKknAMKxT99o9qUTRVC6m")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     Bip44(key.clone(), KeychainKind::External),
 ///     Some(Bip44(key, KeychainKind::Internal)),
 ///     Network::Testnet,
@@ -226,7 +226,7 @@ impl<K: DerivableKey<Legacy>> DescriptorTemplate for Bip44<K> {
 ///
 /// let key = bitcoin::util::bip32::ExtendedPubKey::from_str("tpubDDDzQ31JkZB7VxUr9bjvBivDdqoFLrDPyLWtLapArAi51ftfmCb2DPxwLQzX65iNcXz1DGaVvyvo6JQ6rTU73r2gqdEo8uov9QKRb7nKCSU")?;
 /// let fingerprint = bitcoin::util::bip32::Fingerprint::from_str("c55b303f")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     Bip44Public(key.clone(), fingerprint, KeychainKind::External),
 ///     Some(Bip44Public(key, fingerprint, KeychainKind::Internal)),
 ///     Network::Testnet,
@@ -262,7 +262,7 @@ impl<K: DerivableKey<Legacy>> DescriptorTemplate for Bip44Public<K> {
 /// use bdk::template::Bip49;
 ///
 /// let key = bitcoin::util::bip32::ExtendedPrivKey::from_str("tprv8ZgxMBicQKsPeZRHk4rTG6orPS2CRNFX3njhUXx5vj9qGog5ZMH4uGReDWN5kCkY3jmWEtWause41CDvBRXD1shKknAMKxT99o9qUTRVC6m")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     Bip49(key.clone(), KeychainKind::External),
 ///     Some(Bip49(key, KeychainKind::Internal)),
 ///     Network::Testnet,
@@ -302,7 +302,7 @@ impl<K: DerivableKey<Segwitv0>> DescriptorTemplate for Bip49<K> {
 ///
 /// let key = bitcoin::util::bip32::ExtendedPubKey::from_str("tpubDC49r947KGK52X5rBWS4BLs5m9SRY3pYHnvRrm7HcybZ3BfdEsGFyzCMzayi1u58eT82ZeyFZwH7DD6Q83E3fM9CpfMtmnTygnLfP59jL9L")?;
 /// let fingerprint = bitcoin::util::bip32::Fingerprint::from_str("c55b303f")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     Bip49Public(key.clone(), fingerprint, KeychainKind::External),
 ///     Some(Bip49Public(key, fingerprint, KeychainKind::Internal)),
 ///     Network::Testnet,
@@ -338,7 +338,7 @@ impl<K: DerivableKey<Segwitv0>> DescriptorTemplate for Bip49Public<K> {
 /// use bdk::template::Bip84;
 ///
 /// let key = bitcoin::util::bip32::ExtendedPrivKey::from_str("tprv8ZgxMBicQKsPeZRHk4rTG6orPS2CRNFX3njhUXx5vj9qGog5ZMH4uGReDWN5kCkY3jmWEtWause41CDvBRXD1shKknAMKxT99o9qUTRVC6m")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     Bip84(key.clone(), KeychainKind::External),
 ///     Some(Bip84(key, KeychainKind::Internal)),
 ///     Network::Testnet,
@@ -378,7 +378,7 @@ impl<K: DerivableKey<Segwitv0>> DescriptorTemplate for Bip84<K> {
 ///
 /// let key = bitcoin::util::bip32::ExtendedPubKey::from_str("tpubDC2Qwo2TFsaNC4ju8nrUJ9mqVT3eSgdmy1yPqhgkjwmke3PRXutNGRYAUo6RCHTcVQaDR3ohNU9we59brGHuEKPvH1ags2nevW5opEE9Z5Q")?;
 /// let fingerprint = bitcoin::util::bip32::Fingerprint::from_str("c55b303f")?;
-/// let wallet = Wallet::new_offline(
+/// let wallet = Wallet::new(
 ///     Bip84Public(key.clone(), fingerprint, KeychainKind::External),
 ///     Some(Bip84Public(key, fingerprint, KeychainKind::Internal)),
 ///     Network::Testnet,

src/error.rs

@@ -11,6 +11,7 @@
 
 use std::fmt;
 
+use crate::bitcoin::Network;
 use crate::{descriptor, wallet, wallet::address_validator};
 use bitcoin::OutPoint;
 
@@ -23,10 +24,6 @@ pub enum Error {
     Generic(String),
     /// This error is thrown when trying to convert Bare and Public key script to address
     ScriptDoesntHaveAddressForm,
-    /// Found multiple outputs when `single_recipient` option has been specified
-    SingleRecipientMultipleOutputs,
-    /// `single_recipient` option is selected but neither `drain_wallet` nor `manually_selected_only` are
-    SingleRecipientNoInputs,
     /// Cannot build a tx without recipients
     NoRecipients,
     /// `manually_selected_only` option is selected but no utxo has been passed
@@ -64,6 +61,8 @@ pub enum Error {
         /// Required fee absolute value (satoshi)
         required: u64,
     },
+    /// Node doesn't have data to estimate a fee rate
+    FeeRateUnavailable,
     /// In order to use the [`TxBuilder::add_global_xpubs`] option every extended
     /// key in the descriptor must either be a master key itself (having depth = 0) or have an
     /// explicit origin provided
@@ -80,6 +79,16 @@ pub enum Error {
     InvalidPolicyPathError(crate::descriptor::policy::PolicyError),
     /// Signing error
     Signer(crate::wallet::signer::SignerError),
+    /// Invalid network
+    InvalidNetwork {
+        /// requested network, for example what is given as bdk-cli option
+        requested: Network,
+        /// found network, for example the network of the bitcoin node
+        found: Network,
+    },
+    #[cfg(feature = "verify")]
+    /// Transaction verification error
+    Verification(crate::wallet::verify::VerifyError),
 
     /// Progress value must be between `0.0` (included) and `100.0` (included)
     InvalidProgressValue(f32),
@@ -106,6 +115,8 @@ pub enum Error {
     Hex(bitcoin::hashes::hex::Error),
     /// Partially signed bitcoin transaction error
     Psbt(bitcoin::util::psbt::Error),
+    /// Partially signed bitcoin transaction parse error
+    PsbtParse(bitcoin::util::psbt::PsbtParseError),
 
     //KeyMismatch(bitcoin::secp256k1::PublicKey, bitcoin::secp256k1::PublicKey),
     //MissingInputUTXO(usize),
@@ -119,13 +130,19 @@ pub enum Error {
     Electrum(electrum_client::Error),
     #[cfg(feature = "esplora")]
     /// Esplora client error
-    Esplora(crate::blockchain::esplora::EsploraError),
+    Esplora(Box<crate::blockchain::esplora::EsploraError>),
     #[cfg(feature = "compact_filters")]
     /// Compact filters client error)
     CompactFilters(crate::blockchain::compact_filters::CompactFiltersError),
     #[cfg(feature = "key-value-db")]
     /// Sled database error
     Sled(sled::Error),
+    #[cfg(feature = "rpc")]
+    /// Rpc client error
+    Rpc(bitcoincore_rpc::Error),
+    #[cfg(feature = "sqlite")]
+    /// Rusqlite client error
+    Rusqlite(rusqlite::Error),
 }
 
 impl fmt::Display for Error {
@@ -172,13 +189,16 @@ impl_error!(bitcoin::secp256k1::Error, Secp256k1);
 impl_error!(serde_json::Error, Json);
 impl_error!(bitcoin::hashes::hex::Error, Hex);
 impl_error!(bitcoin::util::psbt::Error, Psbt);
+impl_error!(bitcoin::util::psbt::PsbtParseError, PsbtParse);
 
 #[cfg(feature = "electrum")]
 impl_error!(electrum_client::Error, Electrum);
-#[cfg(feature = "esplora")]
-impl_error!(crate::blockchain::esplora::EsploraError, Esplora);
 #[cfg(feature = "key-value-db")]
 impl_error!(sled::Error, Sled);
+#[cfg(feature = "rpc")]
+impl_error!(bitcoincore_rpc::Error, Rpc);
+#[cfg(feature = "sqlite")]
+impl_error!(rusqlite::Error, Rusqlite);
 
 #[cfg(feature = "compact_filters")]
 impl From<crate::blockchain::compact_filters::CompactFiltersError> for Error {
@@ -189,3 +209,20 @@ impl From<crate::blockchain::compact_filters::CompactFiltersError> for Error {
         }
     }
 }
+
+#[cfg(feature = "verify")]
+impl From<crate::wallet::verify::VerifyError> for Error {
+    fn from(other: crate::wallet::verify::VerifyError) -> Self {
+        match other {
+            crate::wallet::verify::VerifyError::Global(inner) => *inner,
+            err => Error::Verification(err),
+        }
+    }
+}
+
+#[cfg(feature = "esplora")]
+impl From<crate::blockchain::esplora::EsploraError> for Error {
+    fn from(other: crate::blockchain::esplora::EsploraError) -> Self {
+        Error::Esplora(Box::new(other))
+    }
+}

src/keys/bip39.rs

@@ -19,7 +19,23 @@ use bitcoin::Network;
 
 use miniscript::ScriptContext;
 
-pub use bip39::{Language, Mnemonic, MnemonicType, Seed};
+pub use bip39::{Language, Mnemonic};
+
+type Seed = [u8; 64];
+
+/// Type describing entropy length (aka word count) in the mnemonic
+pub enum WordCount {
+    /// 12 words mnemonic (128 bits entropy)
+    Words12 = 128,
+    /// 15 words mnemonic (160 bits entropy)
+    Words15 = 160,
+    /// 18 words mnemonic (192 bits entropy)
+    Words18 = 192,
+    /// 21 words mnemonic (224 bits entropy)
+    Words21 = 224,
+    /// 24 words mnemonic (256 bits entropy)
+    Words24 = 256,
+}
 
 use super::{
     any_network, DerivableKey, DescriptorKey, ExtendedKey, GeneratableKey, GeneratedKey, KeyError,
@@ -40,7 +56,7 @@ pub type MnemonicWithPassphrase = (Mnemonic, Option<String>);
 #[cfg_attr(docsrs, doc(cfg(feature = "keys-bip39")))]
 impl<Ctx: ScriptContext> DerivableKey<Ctx> for Seed {
     fn into_extended_key(self) -> Result<ExtendedKey<Ctx>, KeyError> {
-        Ok(bip32::ExtendedPrivKey::new_master(Network::Bitcoin, &self.as_bytes())?.into())
+        Ok(bip32::ExtendedPrivKey::new_master(Network::Bitcoin, &self[..])?.into())
     }
 
     fn into_descriptor_key(
@@ -60,7 +76,7 @@ impl<Ctx: ScriptContext> DerivableKey<Ctx> for Seed {
 impl<Ctx: ScriptContext> DerivableKey<Ctx> for MnemonicWithPassphrase {
     fn into_extended_key(self) -> Result<ExtendedKey<Ctx>, KeyError> {
         let (mnemonic, passphrase) = self;
-        let seed = Seed::new(&mnemonic, passphrase.as_deref().unwrap_or(""));
+        let seed: Seed = mnemonic.to_seed(passphrase.as_deref().unwrap_or(""));
 
         seed.into_extended_key()
     }
@@ -101,15 +117,15 @@ impl<Ctx: ScriptContext> DerivableKey<Ctx> for Mnemonic {
 impl<Ctx: ScriptContext> GeneratableKey<Ctx> for Mnemonic {
     type Entropy = [u8; 32];
 
-    type Options = (MnemonicType, Language);
-    type Error = Option<bip39::ErrorKind>;
+    type Options = (WordCount, Language);
+    type Error = Option<bip39::Error>;
 
     fn generate_with_entropy(
-        (mnemonic_type, language): Self::Options,
+        (word_count, language): Self::Options,
         entropy: Self::Entropy,
     ) -> Result<GeneratedKey<Self, Ctx>, Self::Error> {
-        let entropy = &entropy.as_ref()[..(mnemonic_type.entropy_bits() / 8)];
-        let mnemonic = Mnemonic::from_entropy(entropy, language).map_err(|e| e.downcast().ok())?;
+        let entropy = &entropy.as_ref()[..(word_count as usize / 8)];
+        let mnemonic = Mnemonic::from_entropy_in(language, entropy)?;
 
         Ok(GeneratedKey::new(mnemonic, any_network()))
     }
@@ -121,15 +137,17 @@ mod test {
 
     use bitcoin::util::bip32;
 
-    use bip39::{Language, Mnemonic, MnemonicType};
+    use bip39::{Language, Mnemonic};
 
     use crate::keys::{any_network, GeneratableKey, GeneratedKey};
 
+    use super::WordCount;
+
     #[test]
     fn test_keys_bip39_mnemonic() {
         let mnemonic =
             "aim bunker wash balance finish force paper analyst cabin spoon stable organ";
-        let mnemonic = Mnemonic::from_phrase(mnemonic, Language::English).unwrap();
+        let mnemonic = Mnemonic::parse_in(Language::English, mnemonic).unwrap();
         let path = bip32::DerivationPath::from_str("m/44'/0'/0'/0").unwrap();
 
         let key = (mnemonic, path);
@@ -143,7 +161,7 @@ mod test {
     fn test_keys_bip39_mnemonic_passphrase() {
         let mnemonic =
             "aim bunker wash balance finish force paper analyst cabin spoon stable organ";
-        let mnemonic = Mnemonic::from_phrase(mnemonic, Language::English).unwrap();
+        let mnemonic = Mnemonic::parse_in(Language::English, mnemonic).unwrap();
         let path = bip32::DerivationPath::from_str("m/44'/0'/0'/0").unwrap();
 
         let key = ((mnemonic, Some("passphrase".into())), path);
@@ -157,7 +175,7 @@ mod test {
     fn test_keys_generate_bip39() {
         let generated_mnemonic: GeneratedKey<_, miniscript::Segwitv0> =
             Mnemonic::generate_with_entropy(
-                (MnemonicType::Words12, Language::English),
+                (WordCount::Words12, Language::English),
                 crate::keys::test::TEST_ENTROPY,
             )
             .unwrap();
@@ -169,7 +187,7 @@ mod test {
 
         let generated_mnemonic: GeneratedKey<_, miniscript::Segwitv0> =
             Mnemonic::generate_with_entropy(
-                (MnemonicType::Words24, Language::English),
+                (WordCount::Words24, Language::English),
                 crate::keys::test::TEST_ENTROPY,
             )
             .unwrap();
@@ -180,11 +198,11 @@ mod test {
     #[test]
     fn test_keys_generate_bip39_random() {
         let generated_mnemonic: GeneratedKey<_, miniscript::Segwitv0> =
-            Mnemonic::generate((MnemonicType::Words12, Language::English)).unwrap();
+            Mnemonic::generate((WordCount::Words12, Language::English)).unwrap();
         assert_eq!(generated_mnemonic.valid_networks, any_network());
 
         let generated_mnemonic: GeneratedKey<_, miniscript::Segwitv0> =
-            Mnemonic::generate((MnemonicType::Words24, Language::English)).unwrap();
+            Mnemonic::generate((WordCount::Words24, Language::English)).unwrap();
         assert_eq!(generated_mnemonic.valid_networks, any_network());
     }
 }

src/keys/mod.rs

@@ -319,6 +319,7 @@ impl<Ctx: ScriptContext> ExtendedKey<Ctx> {
         match self {
             ExtendedKey::Private((mut xprv, _)) => {
                 xprv.network = network;
+                xprv.private_key.network = network;
                 Some(xprv)
             }
             ExtendedKey::Public(_) => None,
@@ -356,7 +357,7 @@ impl<Ctx: ScriptContext> From<bip32::ExtendedPrivKey> for ExtendedKey<Ctx> {
 
 /// Trait for keys that can be derived.
 ///
-/// When extra metadata are provided, a [`DerivableKey`] can be transofrmed into a
+/// When extra metadata are provided, a [`DerivableKey`] can be transformed into a
 /// [`DescriptorKey`]: the trait [`IntoDescriptorKey`] is automatically implemented
 /// for `(DerivableKey, DerivationPath)` and
 /// `(DerivableKey, KeySource, DerivationPath)` tuples.
@@ -460,9 +461,9 @@ use bdk::keys::bip39::{Mnemonic, Language};
 
 # fn main() -> Result<(), Box<dyn std::error::Error>> {
 let xkey: ExtendedKey =
-    Mnemonic::from_phrase(
+    Mnemonic::parse_in(
+        Language::English,
         "jelly crash boy whisper mouse ecology tuna soccer memory million news short",
-        Language::English
     )?
     .into_extended_key()?;
 let xprv = xkey.into_xprv(Network::Bitcoin).unwrap();
@@ -748,7 +749,21 @@ pub fn make_pk<Pk: IntoDescriptorKey<Ctx>, Ctx: ScriptContext>(
     let (key, key_map, valid_networks) = descriptor_key.into_descriptor_key()?.extract(secp)?;
     let minisc = Miniscript::from_ast(Terminal::PkK(key))?;
 
-    minisc.check_minsicript()?;
+    minisc.check_miniscript()?;
+
+    Ok((minisc, key_map, valid_networks))
+}
+
+// Used internally by `bdk::fragment!` to build `pk_h()` fragments
+#[doc(hidden)]
+pub fn make_pkh<Pk: IntoDescriptorKey<Ctx>, Ctx: ScriptContext>(
+    descriptor_key: Pk,
+    secp: &SecpCtx,
+) -> Result<(Miniscript<DescriptorPublicKey, Ctx>, KeyMap, ValidNetworks), DescriptorError> {
+    let (key, key_map, valid_networks) = descriptor_key.into_descriptor_key()?.extract(secp)?;
+    let minisc = Miniscript::from_ast(Terminal::PkH(key))?;
+
+    minisc.check_miniscript()?;
 
     Ok((minisc, key_map, valid_networks))
 }
@@ -763,7 +778,7 @@ pub fn make_multi<Pk: IntoDescriptorKey<Ctx>, Ctx: ScriptContext>(
     let (pks, key_map, valid_networks) = expand_multi_keys(pks, secp)?;
     let minisc = Miniscript::from_ast(Terminal::Multi(thresh, pks))?;
 
-    minisc.check_minsicript()?;
+    minisc.check_miniscript()?;
 
     Ok((minisc, key_map, valid_networks))
 }
@@ -917,4 +932,43 @@ pub mod test {
             "L2wTu6hQrnDMiFNWA5na6jB12ErGQqtXwqpSL7aWquJaZG8Ai3ch"
         );
     }
+
+    #[test]
+    fn test_keys_wif_network() {
+        // test mainnet wif
+        let generated_xprv: GeneratedKey<_, miniscript::Segwitv0> =
+            bip32::ExtendedPrivKey::generate_with_entropy_default(TEST_ENTROPY).unwrap();
+        let xkey = generated_xprv.into_extended_key().unwrap();
+
+        let network = Network::Bitcoin;
+        let xprv = xkey.into_xprv(network).unwrap();
+        let wif = PrivateKey::from_wif(&xprv.private_key.to_wif()).unwrap();
+        assert_eq!(wif.network, network);
+
+        // test testnet wif
+        let generated_xprv: GeneratedKey<_, miniscript::Segwitv0> =
+            bip32::ExtendedPrivKey::generate_with_entropy_default(TEST_ENTROPY).unwrap();
+        let xkey = generated_xprv.into_extended_key().unwrap();
+
+        let network = Network::Testnet;
+        let xprv = xkey.into_xprv(network).unwrap();
+        let wif = PrivateKey::from_wif(&xprv.private_key.to_wif()).unwrap();
+        assert_eq!(wif.network, network);
+    }
+
+    #[cfg(feature = "keys-bip39")]
+    #[test]
+    fn test_keys_wif_network_bip39() {
+        let xkey: ExtendedKey = bip39::Mnemonic::parse_in(
+            bip39::Language::English,
+            "jelly crash boy whisper mouse ecology tuna soccer memory million news short",
+        )
+        .unwrap()
+        .into_extended_key()
+        .unwrap();
+        let xprv = xkey.into_xprv(Network::Testnet).unwrap();
+        let wif = PrivateKey::from_wif(&xprv.private_key.to_wif()).unwrap();
+
+        assert_eq!(wif.network, Network::Testnet);
+    }
 }

src/lib.rs

@@ -14,6 +14,10 @@
 // only enables the `doc_cfg` feature when
 // the `docsrs` configuration attribute is defined
 #![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(
+    docsrs,
+    doc(html_logo_url = "https://github.com/bitcoindevkit/bdk/raw/master/static/bdk.png")
+)]
 
 //! A modern, lightweight, descriptor-based wallet library written in Rust.
 //!
@@ -40,7 +44,7 @@
 //! interact with the bitcoin P2P network.
 //!
 //! ```toml
-//! bdk = "0.8.0"
+//! bdk = "0.15.0"
 //! ```
 #![cfg_attr(
     feature = "electrum",
@@ -49,22 +53,22 @@
 
 ### Example
 ```no_run
-use bdk::Wallet;
+use bdk::{Wallet, SyncOptions};
 use bdk::database::MemoryDatabase;
-use bdk::blockchain::{noop_progress, ElectrumBlockchain};
+use bdk::blockchain::ElectrumBlockchain;
 use bdk::electrum_client::Client;
 
 fn main() -> Result<(), bdk::Error> {
     let client = Client::new("ssl://electrum.blockstream.info:60002")?;
+    let blockchain = ElectrumBlockchain::from(client);
     let wallet = Wallet::new(
         "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/0/*)",
         Some("wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"),
         bitcoin::Network::Testnet,
         MemoryDatabase::default(),
-        ElectrumBlockchain::from(client)
     )?;
 
-    wallet.sync(noop_progress(), None)?;
+    wallet.sync(&blockchain, SyncOptions::default())?;
 
     println!("Descriptor balance: {} SAT", wallet.get_balance()?);
 
@@ -83,7 +87,7 @@ fn main() -> Result<(), bdk::Error> {
 //! use bdk::wallet::AddressIndex::New;
 //!
 //! fn main() -> Result<(), bdk::Error> {
-//! let wallet = Wallet::new_offline(
+//! let wallet = Wallet::new(
 //!         "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/0/*)",
 //!         Some("wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"),
 //!         bitcoin::Network::Testnet,
@@ -104,11 +108,9 @@ fn main() -> Result<(), bdk::Error> {
 
 ### Example
 ```no_run
-use base64::decode;
-
-use bdk::{FeeRate, Wallet};
+use bdk::{FeeRate, Wallet, SyncOptions};
 use bdk::database::MemoryDatabase;
-use bdk::blockchain::{noop_progress, ElectrumBlockchain};
+use bdk::blockchain::ElectrumBlockchain;
 use bdk::electrum_client::Client;
 
 use bitcoin::consensus::serialize;
@@ -121,10 +123,10 @@ fn main() -> Result<(), bdk::Error> {
         Some("wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"),
         bitcoin::Network::Testnet,
         MemoryDatabase::default(),
-        ElectrumBlockchain::from(client)
     )?;
+    let blockchain = ElectrumBlockchain::from(client);
 
-    wallet.sync(noop_progress(), None)?;
+    wallet.sync(&blockchain, SyncOptions::default())?;
 
     let send_to = wallet.get_address(New)?;
     let (psbt, details) = {
@@ -138,7 +140,7 @@ fn main() -> Result<(), bdk::Error> {
     };
 
     println!("Transaction details: {:#?}", details);
-    println!("Unsigned PSBT: {}", base64::encode(&serialize(&psbt)));
+    println!("Unsigned PSBT: {}", &psbt);
 
     Ok(())
 }
@@ -150,14 +152,15 @@ fn main() -> Result<(), bdk::Error> {
 //!
 //! ### Example
 //! ```no_run
-//! use base64::decode;
-//! use bitcoin::consensus::deserialize;
+//! use std::str::FromStr;
+//!
+//! use bitcoin::util::psbt::PartiallySignedTransaction as Psbt;
 //!
 //! use bdk::{Wallet, SignOptions};
 //! use bdk::database::MemoryDatabase;
 //!
 //! fn main() -> Result<(), bdk::Error> {
-//!     let wallet = Wallet::new_offline(
+//!     let wallet = Wallet::new(
 //!         "wpkh([c258d2e4/84h/1h/0h]tprv8griRPhA7342zfRyB6CqeKF8CJDXYu5pgnj1cjL1u2ngKcJha5jjTRimG82ABzJQ4MQe71CV54xfn25BbhCNfEGGJZnxvCDQCd6JkbvxW6h/0/*)",
 //!         Some("wpkh([c258d2e4/84h/1h/0h]tprv8griRPhA7342zfRyB6CqeKF8CJDXYu5pgnj1cjL1u2ngKcJha5jjTRimG82ABzJQ4MQe71CV54xfn25BbhCNfEGGJZnxvCDQCd6JkbvxW6h/1/*)"),
 //!         bitcoin::Network::Testnet,
@@ -165,7 +168,7 @@ fn main() -> Result<(), bdk::Error> {
 //!     )?;
 //!
 //!     let psbt = "...";
-//!     let mut psbt = deserialize(&base64::decode(psbt).unwrap())?;
+//!     let mut psbt = Psbt::from_str(psbt)?;
 //!
 //!     let finalized = wallet.sign(&mut psbt, SignOptions::default())?;
 //!
@@ -206,11 +209,24 @@ extern crate serde;
 #[macro_use]
 extern crate serde_json;
 
+#[cfg(all(feature = "reqwest", feature = "ureq"))]
+compile_error!("Features reqwest and ureq are mutually exclusive and cannot be enabled together");
+
 #[cfg(all(feature = "async-interface", feature = "electrum"))]
 compile_error!(
     "Features async-interface and electrum are mutually exclusive and cannot be enabled together"
 );
 
+#[cfg(all(feature = "async-interface", feature = "ureq"))]
+compile_error!(
+    "Features async-interface and ureq are mutually exclusive and cannot be enabled together"
+);
+
+#[cfg(all(feature = "async-interface", feature = "compact_filters"))]
+compile_error!(
+    "Features async-interface and compact_filters are mutually exclusive and cannot be enabled together"
+);
+
 #[cfg(feature = "keys-bip39")]
 extern crate bip39;
 
@@ -223,22 +239,19 @@ extern crate bdk_macros;
 #[cfg(feature = "compact_filters")]
 extern crate lazy_static;
 
+#[cfg(feature = "rpc")]
+pub extern crate bitcoincore_rpc;
+
 #[cfg(feature = "electrum")]
 pub extern crate electrum_client;
 
-#[cfg(feature = "esplora")]
-pub extern crate reqwest;
-
 #[cfg(feature = "key-value-db")]
 pub extern crate sled;
 
-#[allow(unused_imports)]
-#[cfg(test)]
-#[allow(unused_imports)]
-#[cfg(test)]
-#[macro_use]
-pub extern crate serial_test;
+#[cfg(feature = "sqlite")]
+pub extern crate rusqlite;
 
+#[allow(unused_imports)]
 #[macro_use]
 pub(crate) mod error;
 pub mod blockchain;
@@ -259,6 +272,7 @@ pub use wallet::address_validator;
 pub use wallet::signer;
 pub use wallet::signer::SignOptions;
 pub use wallet::tx_builder::TxBuilder;
+pub use wallet::SyncOptions;
 pub use wallet::Wallet;
 
 /// Get the version of BDK at runtime
@@ -266,7 +280,7 @@ pub fn version() -> &'static str {
     env!("CARGO_PKG_VERSION", "unknown")
 }
 
-// We should consider putting this under a feature flag but we need the macro in doctets so we need
+// We should consider putting this under a feature flag but we need the macro in doctests so we need
 // to wait until https://github.com/rust-lang/rust/issues/67295 is fixed.
 //
 // Stuff in here is too rough to document atm

src/psbt/mod.rs

@@ -41,12 +41,12 @@ impl PsbtUtils for Psbt {
 
 #[cfg(test)]
 mod test {
-    use crate::bitcoin::consensus::deserialize;
     use crate::bitcoin::TxIn;
     use crate::psbt::Psbt;
-    use crate::wallet::test::{get_funded_wallet, get_test_wpkh};
     use crate::wallet::AddressIndex;
+    use crate::wallet::{get_funded_wallet, test::get_test_wpkh};
     use crate::SignOptions;
+    use std::str::FromStr;
 
     // from bip 174
     const PSBT_STR: &str = "cHNidP8BAKACAAAAAqsJSaCMWvfEm4IS9Bfi8Vqz9cM9zxU4IagTn4d6W3vkAAAAAAD+////qwlJoIxa98SbghL0F+LxWrP1wz3PFTghqBOfh3pbe+QBAAAAAP7///8CYDvqCwAAAAAZdqkUdopAu9dAy+gdmI5x3ipNXHE5ax2IrI4kAAAAAAAAGXapFG9GILVT+glechue4O/p+gOcykWXiKwAAAAAAAEHakcwRAIgR1lmF5fAGwNrJZKJSGhiGDR9iYZLcZ4ff89X0eURZYcCIFMJ6r9Wqk2Ikf/REf3xM286KdqGbX+EhtdVRs7tr5MZASEDXNxh/HupccC1AaZGoqg7ECy0OIEhfKaC3Ibi1z+ogpIAAQEgAOH1BQAAAAAXqRQ1RebjO4MsRwUPJNPuuTycA5SLx4cBBBYAFIXRNTfy4mVAWjTbr6nj3aAfuCMIAAAA";
@@ -54,7 +54,7 @@ mod test {
     #[test]
     #[should_panic(expected = "InputIndexOutOfRange")]
     fn test_psbt_malformed_psbt_input_legacy() {
-        let psbt_bip: Psbt = deserialize(&base64::decode(PSBT_STR).unwrap()).unwrap();
+        let psbt_bip = Psbt::from_str(PSBT_STR).unwrap();
         let (wallet, _, _) = get_funded_wallet(get_test_wpkh());
         let send_to = wallet.get_address(AddressIndex::New).unwrap();
         let mut builder = wallet.build_tx();
@@ -71,7 +71,7 @@ mod test {
     #[test]
     #[should_panic(expected = "InputIndexOutOfRange")]
     fn test_psbt_malformed_psbt_input_segwit() {
-        let psbt_bip: Psbt = deserialize(&base64::decode(PSBT_STR).unwrap()).unwrap();
+        let psbt_bip = Psbt::from_str(PSBT_STR).unwrap();
         let (wallet, _, _) = get_funded_wallet(get_test_wpkh());
         let send_to = wallet.get_address(AddressIndex::New).unwrap();
         let mut builder = wallet.build_tx();
@@ -103,7 +103,7 @@ mod test {
 
     #[test]
     fn test_psbt_sign_with_finalized() {
-        let psbt_bip: Psbt = deserialize(&base64::decode(PSBT_STR).unwrap()).unwrap();
+        let psbt_bip = Psbt::from_str(PSBT_STR).unwrap();
         let (wallet, _, _) = get_funded_wallet(get_test_wpkh());
         let send_to = wallet.get_address(AddressIndex::New).unwrap();
         let mut builder = wallet.build_tx();

src/testutils/mod.rs

@@ -10,6 +10,7 @@
 // licenses.
 #![allow(missing_docs)]
 
+#[cfg(test)]
 #[cfg(feature = "test-blockchains")]
 pub mod blockchain_tests;
 
@@ -99,8 +100,8 @@ impl TranslateDescriptor for Descriptor<DescriptorPublicKey> {
 #[macro_export]
 macro_rules! testutils {
     ( @external $descriptors:expr, $child:expr ) => ({
-        use bitcoin::secp256k1::Secp256k1;
-        use miniscript::descriptor::{Descriptor, DescriptorPublicKey, DescriptorTrait};
+        use $crate::bitcoin::secp256k1::Secp256k1;
+        use $crate::miniscript::descriptor::{Descriptor, DescriptorPublicKey, DescriptorTrait};
 
         use $crate::testutils::TranslateDescriptor;
 
@@ -110,15 +111,15 @@ macro_rules! testutils {
         parsed.derive_translated(&secp, $child).address(bitcoin::Network::Regtest).expect("No address form")
     });
     ( @internal $descriptors:expr, $child:expr ) => ({
-        use bitcoin::secp256k1::Secp256k1;
-        use miniscript::descriptor::{Descriptor, DescriptorPublicKey, DescriptorTrait};
+        use $crate::bitcoin::secp256k1::Secp256k1;
+        use $crate::miniscript::descriptor::{Descriptor, DescriptorPublicKey, DescriptorTrait};
 
         use $crate::testutils::TranslateDescriptor;
 
         let secp = Secp256k1::new();
 
         let parsed = Descriptor::<DescriptorPublicKey>::parse_descriptor(&secp, &$descriptors.1.expect("Missing internal descriptor")).expect("Failed to parse descriptor in `testutils!(@internal)`").0;
-        parsed.derive_translated(&secp, $child).address(bitcoin::Network::Regtest).expect("No address form")
+        parsed.derive_translated(&secp, $child).address($crate::bitcoin::Network::Regtest).expect("No address form")
     });
     ( @e $descriptors:expr, $child:expr ) => ({ testutils!(@external $descriptors, $child) });
     ( @i $descriptors:expr, $child:expr ) => ({ testutils!(@internal $descriptors, $child) });
@@ -144,8 +145,8 @@ macro_rules! testutils {
         let mut seed = [0u8; 32];
         rand::thread_rng().fill(&mut seed[..]);
 
-        let key = bitcoin::util::bip32::ExtendedPrivKey::new_master(
-            bitcoin::Network::Testnet,
+        let key = $crate::bitcoin::util::bip32::ExtendedPrivKey::new_master(
+            $crate::bitcoin::Network::Testnet,
             &seed,
         );
 
@@ -157,13 +158,13 @@ macro_rules! testutils {
     ( @generate_wif ) => ({
         use rand::Rng;
 
-        let mut key = [0u8; bitcoin::secp256k1::constants::SECRET_KEY_SIZE];
+        let mut key = [0u8; $crate::bitcoin::secp256k1::constants::SECRET_KEY_SIZE];
         rand::thread_rng().fill(&mut key[..]);
 
-        (bitcoin::PrivateKey {
+        ($crate::bitcoin::PrivateKey {
             compressed: true,
-            network: bitcoin::Network::Testnet,
-            key: bitcoin::secp256k1::SecretKey::from_slice(&key).unwrap(),
+            network: $crate::bitcoin::Network::Testnet,
+            key: $crate::bitcoin::secp256k1::SecretKey::from_slice(&key).unwrap(),
         }.to_string(), None::<String>, None::<String>)
     });
 
@@ -180,8 +181,8 @@ macro_rules! testutils {
     ( @descriptors ( $external_descriptor:expr ) $( ( $internal_descriptor:expr ) )? $( ( @keys $( $keys:tt )* ) )* ) => ({
         use std::str::FromStr;
         use std::collections::HashMap;
-        use miniscript::descriptor::Descriptor;
-        use miniscript::TranslatePk;
+        use $crate::miniscript::descriptor::Descriptor;
+        use $crate::miniscript::TranslatePk;
 
         #[allow(unused_assignments, unused_mut)]
         let mut keys: HashMap<&'static str, (String, Option<String>, Option<String>)> = HashMap::new();

src/types.rs

@@ -10,6 +10,7 @@
 // licenses.
 
 use std::convert::AsRef;
+use std::ops::Sub;
 
 use bitcoin::blockdata::transaction::{OutPoint, Transaction, TxOut};
 use bitcoin::{hash_types::Txid, util::psbt};
@@ -65,10 +66,31 @@ impl FeeRate {
         FeeRate(1.0)
     }
 
+    /// Calculate fee rate from `fee` and weight units (`wu`).
+    pub fn from_wu(fee: u64, wu: usize) -> FeeRate {
+        Self::from_vb(fee, wu.vbytes())
+    }
+
+    /// Calculate fee rate from `fee` and `vbytes`.
+    pub fn from_vb(fee: u64, vbytes: usize) -> FeeRate {
+        let rate = fee as f32 / vbytes as f32;
+        Self::from_sat_per_vb(rate)
+    }
+
     /// Return the value as satoshi/vbyte
     pub fn as_sat_vb(&self) -> f32 {
         self.0
     }
+
+    /// Calculate absolute fee in Satoshis using size in weight units.
+    pub fn fee_wu(&self, wu: usize) -> u64 {
+        self.fee_vb(wu.vbytes())
+    }
+
+    /// Calculate absolute fee in Satoshis using size in virtual bytes.
+    pub fn fee_vb(&self, vbytes: usize) -> u64 {
+        (self.as_sat_vb() * vbytes as f32).ceil() as u64
+    }
 }
 
 impl std::default::Default for FeeRate {
@@ -77,10 +99,31 @@ impl std::default::Default for FeeRate {
     }
 }
 
+impl Sub for FeeRate {
+    type Output = Self;
+
+    fn sub(self, other: FeeRate) -> Self::Output {
+        FeeRate(self.0 - other.0)
+    }
+}
+
+/// Trait implemented by types that can be used to measure weight units.
+pub trait Vbytes {
+    /// Convert weight units to virtual bytes.
+    fn vbytes(self) -> usize;
+}
+
+impl Vbytes for usize {
+    fn vbytes(self) -> usize {
+        // ref: https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#transaction-size-calculations
+        (self as f32 / 4.0).ceil() as usize
+    }
+}
+
 /// An unspent output owned by a [`Wallet`].
 ///
 /// [`Wallet`]: crate::Wallet
-#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, Hash)]
 pub struct LocalUtxo {
     /// Reference to a transaction output
     pub outpoint: OutPoint,
@@ -139,7 +182,7 @@ impl Utxo {
                 }
 
                 if let Some(txout) = &psbt_input.witness_utxo {
-                    return &txout;
+                    return txout;
                 }
 
                 unreachable!("Foreign UTXOs will always have one of these set")
@@ -155,16 +198,53 @@ pub struct TransactionDetails {
     pub transaction: Option<Transaction>,
     /// Transaction id
     pub txid: Txid,
-    /// Timestamp
-    pub timestamp: u64,
+
     /// Received value (sats)
     pub received: u64,
     /// Sent value (sats)
     pub sent: u64,
-    /// Fee value (sats)
-    pub fees: u64,
-    /// Confirmed in block height, `None` means unconfirmed
-    pub height: Option<u32>,
+    /// Fee value (sats) if available.
+    /// The availability of the fee depends on the backend. It's never `None` with an Electrum
+    /// Server backend, but it could be `None` with a Bitcoin RPC node without txindex that receive
+    /// funds while offline.
+    pub fee: Option<u64>,
+    /// If the transaction is confirmed, contains height and timestamp of the block containing the
+    /// transaction, unconfirmed transaction contains `None`.
+    pub confirmation_time: Option<BlockTime>,
+    /// Whether the tx has been verified against the consensus rules
+    ///
+    /// Confirmed txs are considered "verified" by default, while unconfirmed txs are checked to
+    /// ensure an unstrusted [`Blockchain`](crate::blockchain::Blockchain) backend can't trick the
+    /// wallet into using an invalid tx as an RBF template.
+    ///
+    /// The check is only performed when the `verify` feature is enabled.
+    #[serde(default = "bool::default")] // default to `false` if not specified
+    pub verified: bool,
+}
+
+/// Block height and timestamp of a block
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, Default)]
+pub struct BlockTime {
+    /// confirmation block height
+    pub height: u32,
+    /// confirmation block timestamp
+    pub timestamp: u64,
+}
+
+/// **DEPRECATED**: Confirmation time of a transaction
+///
+/// The structure has been renamed to `BlockTime`
+#[deprecated(note = "This structure has been renamed to `BlockTime`")]
+pub type ConfirmationTime = BlockTime;
+
+impl BlockTime {
+    /// Returns `Some` `BlockTime` if both `height` and `timestamp` are `Some`
+    pub fn new(height: Option<u32>, timestamp: Option<u64>) -> Option<Self> {
+        match (height, timestamp) {
+            (Some(height), Some(timestamp)) => Some(BlockTime { height, timestamp }),
+            _ => None,
+        }
+    }
 }
 
 #[cfg(test)]

src/wallet/address_validator.rs

@@ -55,7 +55,7 @@
 //! }
 //!
 //! let descriptor = "wpkh(tpubD6NzVbkrYhZ4Xferm7Pz4VnjdcDPFyjVu5K4iZXQ4pVN8Cks4pHVowTBXBKRhX64pkRyJZJN5xAKj4UDNnLPb5p2sSKXhewoYx5GbTdUFWq/*)";
-//! let mut wallet = Wallet::new_offline(descriptor, None, Network::Testnet, MemoryDatabase::default())?;
+//! let mut wallet = Wallet::new(descriptor, None, Network::Testnet, MemoryDatabase::default())?;
 //! wallet.add_address_validator(Arc::new(PrintAddressAndContinue));
 //!
 //! let address = wallet.get_address(New)?;
@@ -115,8 +115,8 @@ mod test {
     use std::sync::Arc;
 
     use super::*;
-    use crate::wallet::test::{get_funded_wallet, get_test_wpkh};
     use crate::wallet::AddressIndex::New;
+    use crate::wallet::{get_funded_wallet, test::get_test_wpkh};
 
     #[derive(Debug)]
     struct TestValidator;

src/wallet/coin_selection.rs

@@ -26,7 +26,7 @@
 //! ```
 //! # use std::str::FromStr;
 //! # use bitcoin::*;
-//! # use bdk::wallet::coin_selection::*;
+//! # use bdk::wallet::{self, coin_selection::*};
 //! # use bdk::database::Database;
 //! # use bdk::*;
 //! # const TXIN_BASE_WEIGHT: usize = (32 + 4 + 4 + 1) * 4;
@@ -41,7 +41,7 @@
 //!         optional_utxos: Vec<WeightedUtxo>,
 //!         fee_rate: FeeRate,
 //!         amount_needed: u64,
-//!         fee_amount: f32,
+//!         fee_amount: u64,
 //!     ) -> Result<CoinSelectionResult, bdk::Error> {
 //!         let mut selected_amount = 0;
 //!         let mut additional_weight = 0;
@@ -57,9 +57,8 @@
 //!                 },
 //!             )
 //!             .collect::<Vec<_>>();
-//!         let additional_fees = additional_weight as f32 * fee_rate.as_sat_vb() / 4.0;
-//!         let amount_needed_with_fees =
-//!             (fee_amount + additional_fees).ceil() as u64 + amount_needed;
+//!         let additional_fees = fee_rate.fee_wu(additional_weight);
+//!         let amount_needed_with_fees = (fee_amount + additional_fees) + amount_needed;
 //!         if amount_needed_with_fees > selected_amount {
 //!             return Err(bdk::Error::InsufficientFunds {
 //!                 needed: amount_needed_with_fees,
@@ -117,7 +116,7 @@ pub struct CoinSelectionResult {
     /// List of outputs selected for use as inputs
     pub selected: Vec<Utxo>,
     /// Total fee amount in satoshi
-    pub fee_amount: f32,
+    pub fee_amount: u64,
 }
 
 impl CoinSelectionResult {
@@ -164,7 +163,7 @@ pub trait CoinSelectionAlgorithm<D: Database>: std::fmt::Debug {
         optional_utxos: Vec<WeightedUtxo>,
         fee_rate: FeeRate,
         amount_needed: u64,
-        fee_amount: f32,
+        fee_amount: u64,
     ) -> Result<CoinSelectionResult, Error>;
 }
 
@@ -183,10 +182,8 @@ impl<D: Database> CoinSelectionAlgorithm<D> for LargestFirstCoinSelection {
         mut optional_utxos: Vec<WeightedUtxo>,
         fee_rate: FeeRate,
         amount_needed: u64,
-        mut fee_amount: f32,
+        mut fee_amount: u64,
     ) -> Result<CoinSelectionResult, Error> {
-        let calc_fee_bytes = |wu| (wu as f32) * fee_rate.as_sat_vb() / 4.0;
-
         log::debug!(
             "amount_needed = `{}`, fee_amount = `{}`, fee_rate = `{:?}`",
             amount_needed,
@@ -211,9 +208,9 @@ impl<D: Database> CoinSelectionAlgorithm<D> for LargestFirstCoinSelection {
             .scan(
                 (&mut selected_amount, &mut fee_amount),
                 |(selected_amount, fee_amount), (must_use, weighted_utxo)| {
-                    if must_use || **selected_amount < amount_needed + (fee_amount.ceil() as u64) {
+                    if must_use || **selected_amount < amount_needed + **fee_amount {
                         **fee_amount +=
-                            calc_fee_bytes(TXIN_BASE_WEIGHT + weighted_utxo.satisfaction_weight);
+                            fee_rate.fee_wu(TXIN_BASE_WEIGHT + weighted_utxo.satisfaction_weight);
                         **selected_amount += weighted_utxo.utxo.txout().value;
 
                         log::debug!(
@@ -230,7 +227,7 @@ impl<D: Database> CoinSelectionAlgorithm<D> for LargestFirstCoinSelection {
             )
             .collect::<Vec<_>>();
 
-        let amount_needed_with_fees = amount_needed + (fee_amount.ceil() as u64);
+        let amount_needed_with_fees = amount_needed + fee_amount;
         if selected_amount < amount_needed_with_fees {
             return Err(Error::InsufficientFunds {
                 needed: amount_needed_with_fees,
@@ -250,16 +247,15 @@ impl<D: Database> CoinSelectionAlgorithm<D> for LargestFirstCoinSelection {
 struct OutputGroup {
     weighted_utxo: WeightedUtxo,
     // Amount of fees for spending a certain utxo, calculated using a certain FeeRate
-    fee: f32,
+    fee: u64,
     // The effective value of the UTXO, i.e., the utxo value minus the fee for spending it
     effective_value: i64,
 }
 
 impl OutputGroup {
     fn new(weighted_utxo: WeightedUtxo, fee_rate: FeeRate) -> Self {
-        let fee = (TXIN_BASE_WEIGHT + weighted_utxo.satisfaction_weight) as f32 / 4.0
-            * fee_rate.as_sat_vb();
-        let effective_value = weighted_utxo.utxo.txout().value as i64 - fee.ceil() as i64;
+        let fee = fee_rate.fee_wu(TXIN_BASE_WEIGHT + weighted_utxo.satisfaction_weight);
+        let effective_value = weighted_utxo.utxo.txout().value as i64 - fee as i64;
         OutputGroup {
             weighted_utxo,
             fee,
@@ -302,7 +298,7 @@ impl<D: Database> CoinSelectionAlgorithm<D> for BranchAndBoundCoinSelection {
         optional_utxos: Vec<WeightedUtxo>,
         fee_rate: FeeRate,
         amount_needed: u64,
-        fee_amount: f32,
+        fee_amount: u64,
     ) -> Result<CoinSelectionResult, Error> {
         // Mapping every (UTXO, usize) to an output group
         let required_utxos: Vec<OutputGroup> = required_utxos
@@ -324,7 +320,7 @@ impl<D: Database> CoinSelectionAlgorithm<D> for BranchAndBoundCoinSelection {
             .iter()
             .fold(0, |acc, x| acc + x.effective_value);
 
-        let actual_target = fee_amount.ceil() as u64 + amount_needed;
+        let actual_target = fee_amount + amount_needed;
         let cost_of_change = self.size_of_change as f32 * fee_rate.as_sat_vb();
 
         let expected = (curr_available_value + curr_value)
@@ -344,6 +340,14 @@ impl<D: Database> CoinSelectionAlgorithm<D> for BranchAndBoundCoinSelection {
             .try_into()
             .expect("Bitcoin amount to fit into i64");
 
+        if curr_value > actual_target {
+            return Ok(BranchAndBoundCoinSelection::calculate_cs_result(
+                vec![],
+                required_utxos,
+                fee_amount,
+            ));
+        }
+
         Ok(self
             .bnb(
                 required_utxos.clone(),
@@ -368,7 +372,7 @@ impl<D: Database> CoinSelectionAlgorithm<D> for BranchAndBoundCoinSelection {
 
 impl BranchAndBoundCoinSelection {
     // TODO: make this more Rust-onic :)
-    // (And perhpaps refactor with less arguments?)
+    // (And perhaps refactor with less arguments?)
     #[allow(clippy::too_many_arguments)]
     fn bnb(
         &self,
@@ -377,7 +381,7 @@ impl BranchAndBoundCoinSelection {
         mut curr_value: i64,
         mut curr_available_value: i64,
         actual_target: i64,
-        fee_amount: f32,
+        fee_amount: u64,
         cost_of_change: f32,
     ) -> Result<CoinSelectionResult, Error> {
         // current_selection[i] will contain true if we are using optional_utxos[i],
@@ -485,7 +489,7 @@ impl BranchAndBoundCoinSelection {
         mut optional_utxos: Vec<OutputGroup>,
         curr_value: i64,
         actual_target: i64,
-        fee_amount: f32,
+        fee_amount: u64,
     ) -> CoinSelectionResult {
         #[cfg(not(test))]
         optional_utxos.shuffle(&mut thread_rng());
@@ -514,10 +518,10 @@ impl BranchAndBoundCoinSelection {
     fn calculate_cs_result(
         mut selected_utxos: Vec<OutputGroup>,
         mut required_utxos: Vec<OutputGroup>,
-        mut fee_amount: f32,
+        mut fee_amount: u64,
     ) -> CoinSelectionResult {
         selected_utxos.append(&mut required_utxos);
-        fee_amount += selected_utxos.iter().map(|u| u.fee).sum::<f32>();
+        fee_amount += selected_utxos.iter().map(|u| u.fee).sum::<u64>();
         let selected = selected_utxos
             .into_iter()
             .map(|u| u.weighted_utxo.utxo)
@@ -539,6 +543,7 @@ mod test {
     use super::*;
     use crate::database::MemoryDatabase;
     use crate::types::*;
+    use crate::wallet::Vbytes;
 
     use rand::rngs::StdRng;
     use rand::seq::SliceRandom;
@@ -546,52 +551,33 @@ mod test {
 
     const P2WPKH_WITNESS_SIZE: usize = 73 + 33 + 2;
 
-    const FEE_AMOUNT: f32 = 50.0;
+    const FEE_AMOUNT: u64 = 50;
+
+    fn utxo(value: u64, index: u32) -> WeightedUtxo {
+        assert!(index < 10);
+        let outpoint = OutPoint::from_str(&format!(
+            "000000000000000000000000000000000000000000000000000000000000000{}:0",
+            index
+        ))
+        .unwrap();
+        WeightedUtxo {
+            satisfaction_weight: P2WPKH_WITNESS_SIZE,
+            utxo: Utxo::Local(LocalUtxo {
+                outpoint,
+                txout: TxOut {
+                    value,
+                    script_pubkey: Script::new(),
+                },
+                keychain: KeychainKind::External,
+            }),
+        }
+    }
 
     fn get_test_utxos() -> Vec<WeightedUtxo> {
         vec![
-            WeightedUtxo {
-                satisfaction_weight: P2WPKH_WITNESS_SIZE,
-                utxo: Utxo::Local(LocalUtxo {
-                    outpoint: OutPoint::from_str(
-                        "0000000000000000000000000000000000000000000000000000000000000000:0",
-                    )
-                    .unwrap(),
-                    txout: TxOut {
-                        value: 100_000,
-                        script_pubkey: Script::new(),
-                    },
-                    keychain: KeychainKind::External,
-                }),
-            },
-            WeightedUtxo {
-                satisfaction_weight: P2WPKH_WITNESS_SIZE,
-                utxo: Utxo::Local(LocalUtxo {
-                    outpoint: OutPoint::from_str(
-                        "0000000000000000000000000000000000000000000000000000000000000001:0",
-                    )
-                    .unwrap(),
-                    txout: TxOut {
-                        value: FEE_AMOUNT as u64 - 40,
-                        script_pubkey: Script::new(),
-                    },
-                    keychain: KeychainKind::External,
-                }),
-            },
-            WeightedUtxo {
-                satisfaction_weight: P2WPKH_WITNESS_SIZE,
-                utxo: Utxo::Local(LocalUtxo {
-                    outpoint: OutPoint::from_str(
-                        "0000000000000000000000000000000000000000000000000000000000000002:0",
-                    )
-                    .unwrap(),
-                    txout: TxOut {
-                        value: 200_000,
-                        script_pubkey: Script::new(),
-                    },
-                    keychain: KeychainKind::Internal,
-                }),
-            },
+            utxo(100_000, 0),
+            utxo(FEE_AMOUNT as u64 - 40, 1),
+            utxo(200_000, 2),
         ]
     }
 
@@ -655,13 +641,13 @@ mod test {
                 vec![],
                 FeeRate::from_sat_per_vb(1.0),
                 250_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
 
         assert_eq!(result.selected.len(), 3);
         assert_eq!(result.selected_amount(), 300_010);
-        assert!((result.fee_amount - 254.0).abs() < f32::EPSILON);
+        assert_eq!(result.fee_amount, 254)
     }
 
     #[test]
@@ -676,13 +662,13 @@ mod test {
                 vec![],
                 FeeRate::from_sat_per_vb(1.0),
                 20_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
 
         assert_eq!(result.selected.len(), 3);
         assert_eq!(result.selected_amount(), 300_010);
-        assert!((result.fee_amount - 254.0).abs() < f32::EPSILON);
+        assert_eq!(result.fee_amount, 254);
     }
 
     #[test]
@@ -697,13 +683,13 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1.0),
                 20_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
 
         assert_eq!(result.selected.len(), 1);
         assert_eq!(result.selected_amount(), 200_000);
-        assert!((result.fee_amount - 118.0).abs() < f32::EPSILON);
+        assert_eq!(result.fee_amount, 118);
     }
 
     #[test]
@@ -719,7 +705,7 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1.0),
                 500_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
     }
@@ -737,7 +723,7 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1000.0),
                 250_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
     }
@@ -757,13 +743,13 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1.0),
                 250_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
 
         assert_eq!(result.selected.len(), 3);
         assert_eq!(result.selected_amount(), 300_000);
-        assert!((result.fee_amount - 254.0).abs() < f32::EPSILON);
+        assert_eq!(result.fee_amount, 254);
     }
 
     #[test]
@@ -784,7 +770,7 @@ mod test {
 
         assert_eq!(result.selected.len(), 3);
         assert_eq!(result.selected_amount(), 300_010);
-        assert!((result.fee_amount - 254.0).abs() < f32::EPSILON);
+        assert_eq!(result.fee_amount, 254);
     }
 
     #[test]
@@ -805,7 +791,38 @@ mod test {
 
         assert_eq!(result.selected.len(), 3);
         assert_eq!(result.selected_amount(), 300010);
-        assert!((result.fee_amount - 254.0).abs() < f32::EPSILON);
+        assert_eq!(result.fee_amount, 254);
+    }
+
+    #[test]
+    fn test_bnb_coin_selection_required_not_enough() {
+        let utxos = get_test_utxos();
+        let database = MemoryDatabase::default();
+
+        let required = vec![utxos[0].clone()];
+        let mut optional = utxos[1..].to_vec();
+        optional.push(utxo(500_000, 3));
+
+        // Defensive assertions, for sanity and in case someone changes the test utxos vector.
+        let amount: u64 = required.iter().map(|u| u.utxo.txout().value).sum();
+        assert_eq!(amount, 100_000);
+        let amount: u64 = optional.iter().map(|u| u.utxo.txout().value).sum();
+        assert!(amount > 150_000);
+
+        let result = BranchAndBoundCoinSelection::default()
+            .coin_select(
+                &database,
+                required,
+                optional,
+                FeeRate::from_sat_per_vb(1.0),
+                150_000,
+                FEE_AMOUNT,
+            )
+            .unwrap();
+
+        assert_eq!(result.selected.len(), 3);
+        assert_eq!(result.selected_amount(), 300_010);
+        assert!((result.fee_amount as f32 - 254.0).abs() < f32::EPSILON);
     }
 
     #[test]
@@ -821,7 +838,7 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1.0),
                 500_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
     }
@@ -839,7 +856,7 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1000.0),
                 250_000,
-                50.0,
+                FEE_AMOUNT,
             )
             .unwrap();
     }
@@ -856,15 +873,15 @@ mod test {
                 utxos,
                 FeeRate::from_sat_per_vb(1.0),
                 99932, // first utxo's effective value
-                0.0,
+                0,
             )
             .unwrap();
 
         assert_eq!(result.selected.len(), 1);
         assert_eq!(result.selected_amount(), 100_000);
-        let input_size = (TXIN_BASE_WEIGHT as f32) / 4.0 + P2WPKH_WITNESS_SIZE as f32 / 4.0;
+        let input_size = (TXIN_BASE_WEIGHT + P2WPKH_WITNESS_SIZE).vbytes();
         let epsilon = 0.5;
-        assert!((1.0 - (result.fee_amount / input_size)).abs() < epsilon);
+        assert!((1.0 - (result.fee_amount as f32 / input_size as f32)).abs() < epsilon);
     }
 
     #[test]
@@ -883,7 +900,7 @@ mod test {
                     optional_utxos,
                     FeeRate::from_sat_per_vb(0.0),
                     target_amount,
-                    0.0,
+                    0,
                 )
                 .unwrap();
             assert_eq!(result.selected_amount(), target_amount);
@@ -910,7 +927,7 @@ mod test {
                 0,
                 curr_available_value,
                 20_000,
-                50.0,
+                FEE_AMOUNT,
                 cost_of_change,
             )
             .unwrap();
@@ -937,7 +954,7 @@ mod test {
                 0,
                 curr_available_value,
                 20_000,
-                50.0,
+                FEE_AMOUNT,
                 cost_of_change,
             )
             .unwrap();
@@ -949,7 +966,6 @@ mod test {
         let fee_rate = FeeRate::from_sat_per_vb(1.0);
         let size_of_change = 31;
         let cost_of_change = size_of_change as f32 * fee_rate.as_sat_vb();
-        let fee_amount = 50.0;
 
         let utxos: Vec<_> = generate_same_value_utxos(50_000, 10)
             .into_iter()
@@ -971,12 +987,12 @@ mod test {
                 curr_value,
                 curr_available_value,
                 target_amount,
-                fee_amount,
+                FEE_AMOUNT,
                 cost_of_change,
             )
             .unwrap();
-        assert!((result.fee_amount - 186.0).abs() < f32::EPSILON);
         assert_eq!(result.selected_amount(), 100_000);
+        assert_eq!(result.fee_amount, 186);
     }
 
     // TODO: bnb() function should be optimized, and this test should be done with more utxos
@@ -1008,7 +1024,7 @@ mod test {
                     curr_value,
                     curr_available_value,
                     target_amount,
-                    0.0,
+                    0,
                     0.0,
                 )
                 .unwrap();
@@ -1034,12 +1050,10 @@ mod test {
             utxos,
             0,
             target_amount as i64,
-            50.0,
+            FEE_AMOUNT,
         );
 
         assert!(result.selected_amount() > target_amount);
-        assert!(
-            (result.fee_amount - (50.0 + result.selected.len() as f32 * 68.0)).abs() < f32::EPSILON
-        );
+        assert_eq!(result.fee_amount, (50 + result.selected.len() * 68) as u64);
     }
 }

src/wallet/export.rs

@@ -30,7 +30,7 @@
 //! }"#;
 //!
 //! let import = WalletExport::from_str(import)?;
-//! let wallet = Wallet::new_offline(
+//! let wallet = Wallet::new(
 //!     &import.descriptor(),
 //!     import.change_descriptor().as_ref(),
 //!     Network::Testnet,
@@ -45,7 +45,7 @@
 //! # use bdk::database::*;
 //! # use bdk::wallet::export::*;
 //! # use bdk::*;
-//! let wallet = Wallet::new_offline(
+//! let wallet = Wallet::new(
 //!     "wpkh([c258d2e4/84h/1h/0h]tpubDD3ynpHgJQW8VvWRzQ5WFDCrs4jqVFGHB3vLC3r49XHJSqP8bHKdK4AriuUKLccK68zfzowx7YhmDN8SiSkgCDENUFx9qVw65YyqM78vyVe/0/*)",
 //!     Some("wpkh([c258d2e4/84h/1h/0h]tpubDD3ynpHgJQW8VvWRzQ5WFDCrs4jqVFGHB3vLC3r49XHJSqP8bHKdK4AriuUKLccK68zfzowx7YhmDN8SiSkgCDENUFx9qVw65YyqM78vyVe/1/*)"),
 //!     Network::Testnet,
@@ -111,8 +111,8 @@ impl WalletExport {
     ///
     /// If the database is empty or `include_blockheight` is false, the `blockheight` field
     /// returned will be `0`.
-    pub fn export_wallet<B, D: BatchDatabase>(
-        wallet: &Wallet<B, D>,
+    pub fn export_wallet<D: BatchDatabase>(
+        wallet: &Wallet<D>,
         label: &str,
         include_blockheight: bool,
     ) -> Result<Self, &'static str> {
@@ -128,7 +128,7 @@ impl WalletExport {
             Ok(txs) => {
                 let mut heights = txs
                     .into_iter()
-                    .map(|tx| tx.height.unwrap_or(0))
+                    .map(|tx| tx.confirmation_time.map(|c| c.height).unwrap_or(0))
                     .collect::<Vec<_>>();
                 heights.sort_unstable();
 
@@ -212,6 +212,7 @@ mod test {
     use crate::database::{memory::MemoryDatabase, BatchOperations};
     use crate::types::TransactionDetails;
     use crate::wallet::Wallet;
+    use crate::BlockTime;
 
     fn get_test_db() -> MemoryDatabase {
         let mut db = MemoryDatabase::new();
@@ -221,11 +222,15 @@ mod test {
                 "4ddff1fa33af17f377f62b72357b43107c19110a8009b36fb832af505efed98a",
             )
             .unwrap(),
-            timestamp: 12345678,
+
             received: 100_000,
             sent: 0,
-            fees: 500,
-            height: Some(5000),
+            fee: Some(500),
+            confirmation_time: Some(BlockTime {
+                timestamp: 12345678,
+                height: 5000,
+            }),
+            verified: true,
         })
         .unwrap();
 
@@ -237,7 +242,7 @@ mod test {
         let descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/0/*)";
         let change_descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/1/*)";
 
-        let wallet = Wallet::new_offline(
+        let wallet = Wallet::new(
             descriptor,
             Some(change_descriptor),
             Network::Bitcoin,
@@ -261,8 +266,7 @@ mod test {
 
         let descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/0/*)";
 
-        let wallet =
-            Wallet::new_offline(descriptor, None, Network::Bitcoin, get_test_db()).unwrap();
+        let wallet = Wallet::new(descriptor, None, Network::Bitcoin, get_test_db()).unwrap();
         WalletExport::export_wallet(&wallet, "Test Label", true).unwrap();
     }
 
@@ -275,7 +279,7 @@ mod test {
         let descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/0/*)";
         let change_descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/50'/0'/1/*)";
 
-        let wallet = Wallet::new_offline(
+        let wallet = Wallet::new(
             descriptor,
             Some(change_descriptor),
             Network::Bitcoin,
@@ -298,7 +302,7 @@ mod test {
                                        [c98b1535/48'/0'/0'/2']tpubDCDi5W4sP6zSnzJeowy8rQDVhBdRARaPhK1axABi8V1661wEPeanpEXj4ZLAUEoikVtoWcyK26TKKJSecSfeKxwHCcRrge9k1ybuiL71z4a/1/*\
                                  ))";
 
-        let wallet = Wallet::new_offline(
+        let wallet = Wallet::new(
             descriptor,
             Some(change_descriptor),
             Network::Testnet,
@@ -318,7 +322,7 @@ mod test {
         let descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/0/*)";
         let change_descriptor = "wpkh(xprv9s21ZrQH143K4CTb63EaMxja1YiTnSEWKMbn23uoEnAzxjdUJRQkazCAtzxGm4LSoTSVTptoV9RbchnKPW9HxKtZumdyxyikZFDLhogJ5Uj/44'/0'/0'/1/*)";
 
-        let wallet = Wallet::new_offline(
+        let wallet = Wallet::new(
             descriptor,
             Some(change_descriptor),
             Network::Bitcoin,

src/wallet/signer.rs

@@ -72,7 +72,7 @@
 //! let custom_signer = CustomSigner::connect();
 //!
 //! let descriptor = "wpkh(tpubD6NzVbkrYhZ4Xferm7Pz4VnjdcDPFyjVu5K4iZXQ4pVN8Cks4pHVowTBXBKRhX64pkRyJZJN5xAKj4UDNnLPb5p2sSKXhewoYx5GbTdUFWq/*)";
-//! let mut wallet = Wallet::new_offline(descriptor, None, Network::Testnet, MemoryDatabase::default())?;
+//! let mut wallet = Wallet::new(descriptor, None, Network::Testnet, MemoryDatabase::default())?;
 //! wallet.add_signer(
 //!     KeychainKind::External,
 //!     SignerOrdering(200),
@@ -143,7 +143,7 @@ pub enum SignerError {
     InvalidNonWitnessUtxo,
     /// The `witness_utxo` field of the transaction is required to sign this input
     MissingWitnessUtxo,
-    /// The `witness_script` field of the transaction is requied to sign this input
+    /// The `witness_script` field of the transaction is required to sign this input
     MissingWitnessScript,
     /// The fingerprint and derivation path are missing from the psbt input
     MissingHdKeypath,
@@ -222,7 +222,7 @@ impl Signer for DescriptorXKey<ExtendedPrivKey> {
             .bip32_derivation
             .iter()
             .filter_map(|(pk, &(fingerprint, ref path))| {
-                if self.matches(&(fingerprint, path.clone()), &secp).is_some() {
+                if self.matches(&(fingerprint, path.clone()), secp).is_some() {
                     Some((pk, path))
                 } else {
                     None
@@ -240,12 +240,12 @@ impl Signer for DescriptorXKey<ExtendedPrivKey> {
                     &full_path.into_iter().cloned().collect::<Vec<ChildNumber>>()
                         [origin_path.len()..],
                 );
-                self.xkey.derive_priv(&secp, &deriv_path).unwrap()
+                self.xkey.derive_priv(secp, &deriv_path).unwrap()
             }
-            None => self.xkey.derive_priv(&secp, &full_path).unwrap(),
+            None => self.xkey.derive_priv(secp, &full_path).unwrap(),
         };
 
-        if &derived_key.private_key.public_key(&secp) != public_key {
+        if &derived_key.private_key.public_key(secp) != public_key {
             Err(SignerError::InvalidKey)
         } else {
             derived_key.private_key.sign(psbt, Some(input_index), secp)
@@ -257,7 +257,7 @@ impl Signer for DescriptorXKey<ExtendedPrivKey> {
     }
 
     fn id(&self, secp: &SecpCtx) -> SignerId {
-        SignerId::from(self.root_fingerprint(&secp))
+        SignerId::from(self.root_fingerprint(secp))
     }
 
     fn descriptor_secret_key(&self) -> Option<DescriptorSecretKey> {
@@ -283,13 +283,13 @@ impl Signer for PrivateKey {
             return Ok(());
         }
 
-        let pubkey = self.public_key(&secp);
+        let pubkey = self.public_key(secp);
         if psbt.inputs[input_index].partial_sigs.contains_key(&pubkey) {
             return Ok(());
         }
 
         // FIXME: use the presence of `witness_utxo` as an indication that we should make a bip143
-        // sig. Does this make sense? Should we add an extra argument to explicitly swith between
+        // sig. Does this make sense? Should we add an extra argument to explicitly switch between
         // these? The original idea was to declare sign() as sign<Ctx: ScriptContex>() and use Ctx,
         // but that violates the rules for trait-objects, so we can't do it.
         let (hash, sighash) = match psbt.inputs[input_index].witness_utxo {
@@ -591,7 +591,7 @@ impl ComputeSighash for Segwitv0 {
                     .map(Script::is_v0_p2wpkh)
                     .unwrap_or(false)
                 {
-                    p2wpkh_script_code(&psbt_input.redeem_script.as_ref().unwrap())
+                    p2wpkh_script_code(psbt_input.redeem_script.as_ref().unwrap())
                 } else {
                     return Err(SignerError::MissingWitnessScript);
                 }

src/wallet/tx_builder.rs

@@ -120,8 +120,8 @@ impl TxBuilderContext for BumpFee {}
 /// [`finish`]: Self::finish
 /// [`coin_selection`]: Self::coin_selection
 #[derive(Debug)]
-pub struct TxBuilder<'a, B, D, Cs, Ctx> {
-    pub(crate) wallet: &'a Wallet<B, D>,
+pub struct TxBuilder<'a, D, Cs, Ctx> {
+    pub(crate) wallet: &'a Wallet<D>,
     pub(crate) params: TxParams,
     pub(crate) coin_selection: Cs,
     pub(crate) phantom: PhantomData<Ctx>,
@@ -133,7 +133,7 @@ pub struct TxBuilder<'a, B, D, Cs, Ctx> {
 pub(crate) struct TxParams {
     pub(crate) recipients: Vec<(Script, u64)>,
     pub(crate) drain_wallet: bool,
-    pub(crate) single_recipient: Option<Script>,
+    pub(crate) drain_to: Option<Script>,
     pub(crate) fee_policy: Option<FeePolicy>,
     pub(crate) internal_policy_path: Option<BTreeMap<String, Vec<usize>>>,
     pub(crate) external_policy_path: Option<BTreeMap<String, Vec<usize>>>,
@@ -170,7 +170,7 @@ impl std::default::Default for FeePolicy {
     }
 }
 
-impl<'a, Cs: Clone, Ctx, B, D> Clone for TxBuilder<'a, B, D, Cs, Ctx> {
+impl<'a, Cs: Clone, Ctx, D> Clone for TxBuilder<'a, D, Cs, Ctx> {
     fn clone(&self) -> Self {
         TxBuilder {
             wallet: self.wallet,
@@ -182,8 +182,8 @@ impl<'a, Cs: Clone, Ctx, B, D> Clone for TxBuilder<'a, B, D, Cs, Ctx> {
 }
 
 // methods supported by both contexts, for any CoinSelectionAlgorithm
-impl<'a, B, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>, Ctx: TxBuilderContext>
-    TxBuilder<'a, B, D, Cs, Ctx>
+impl<'a, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>, Ctx: TxBuilderContext>
+    TxBuilder<'a, D, Cs, Ctx>
 {
     /// Set a custom fee rate
     pub fn fee_rate(&mut self, fee_rate: FeeRate) -> &mut Self {
@@ -310,7 +310,7 @@ impl<'a, B, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>, Ctx: TxBuilderConte
     /// 2. `psbt_input`: To know the value.
     /// 3. `satisfaction_weight`: To know how much weight/vbytes the input will add to the transaction for fee calculation.
     ///
-    /// There are several security concerns about adding foregin UTXOs that application
+    /// There are several security concerns about adding foreign UTXOs that application
     /// developers should consider. First, how do you know the value of the input is correct? If a
     /// `non_witness_utxo` is provided in the `psbt_input` then this method implicitly verifies the
     /// value by checking it against the transaction. If only a `witness_utxo` is provided then this
@@ -508,7 +508,7 @@ impl<'a, B, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>, Ctx: TxBuilderConte
     pub fn coin_selection<P: CoinSelectionAlgorithm<D>>(
         self,
         coin_selection: P,
-    ) -> TxBuilder<'a, B, D, P, Ctx> {
+    ) -> TxBuilder<'a, D, P, Ctx> {
         TxBuilder {
             wallet: self.wallet,
             params: self.params,
@@ -547,7 +547,7 @@ impl<'a, B, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>, Ctx: TxBuilderConte
     }
 }
 
-impl<'a, B, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>> TxBuilder<'a, B, D, Cs, CreateTx> {
+impl<'a, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>> TxBuilder<'a, D, Cs, CreateTx> {
     /// Replace the recipients already added with a new list
     pub fn set_recipients(&mut self, recipients: Vec<(Script, u64)>) -> &mut Self {
         self.params.recipients = recipients;
@@ -560,49 +560,88 @@ impl<'a, B, D: BatchDatabase, Cs: CoinSelectionAlgorithm<D>> TxBuilder<'a, B, D,
         self
     }
 
-    /// Set a single recipient that will get all the selected funds minus the fee. No change will
-    /// be created
-    ///
-    /// This method overrides any recipient set with [`set_recipients`](Self::set_recipients) or
-    /// [`add_recipient`](Self::add_recipient).
-    ///
-    /// It can only be used in conjunction with [`drain_wallet`](Self::drain_wallet) to send the
-    /// entire content of the wallet (minus filters) to a single recipient or with a
-    /// list of manually selected UTXOs by enabling [`manually_selected_only`](Self::manually_selected_only)
-    /// and selecting them with or [`add_utxo`](Self::add_utxo).
-    ///
-    /// When bumping the fees of a transaction made with this option, the user should remeber to
-    /// add [`maintain_single_recipient`](Self::maintain_single_recipient) to correctly update the
-    /// single output instead of adding one more for the change.
-    pub fn set_single_recipient(&mut self, recipient: Script) -> &mut Self {
-        self.params.single_recipient = Some(recipient);
-        self.params.recipients.clear();
+    /// Add data as an output, using OP_RETURN
+    pub fn add_data(&mut self, data: &[u8]) -> &mut Self {
+        let script = Script::new_op_return(data);
+        self.add_recipient(script, 0u64);
+        self
+    }
 
+    /// Sets the address to *drain* excess coins to.
+    ///
+    /// Usually, when there are excess coins they are sent to a change address generated by the
+    /// wallet. This option replaces the usual change address with an arbitrary `script_pubkey` of
+    /// your choosing. Just as with a change output, if the drain output is not needed (the excess
+    /// coins are too small) it will not be included in the resulting transaction. The only
+    /// difference is that it is valid to use `drain_to` without setting any ordinary recipients
+    /// with [`add_recipient`] (but it is perfectly fine to add recipients as well).
+    ///
+    /// When bumping the fees of a transaction made with this option, you probably want to
+    /// use [`allow_shrinking`] to allow this output to be reduced to pay for the extra fees.
+    ///
+    /// # Example
+    ///
+    /// `drain_to` is very useful for draining all the coins in a wallet with [`drain_wallet`] to a
+    /// single address.
+    ///
+    /// ```
+    /// # use std::str::FromStr;
+    /// # use bitcoin::*;
+    /// # use bdk::*;
+    /// # use bdk::wallet::tx_builder::CreateTx;
+    /// # let to_address = Address::from_str("2N4eQYCbKUHCCTUjBJeHcJp9ok6J2GZsTDt").unwrap();
+    /// # let wallet = doctest_wallet!();
+    /// let mut tx_builder = wallet.build_tx();
+    ///
+    /// tx_builder
+    ///     // Spend all outputs in this wallet.
+    ///     .drain_wallet()
+    ///     // Send the excess (which is all the coins minus the fee) to this address.
+    ///     .drain_to(to_address.script_pubkey())
+    ///     .fee_rate(FeeRate::from_sat_per_vb(5.0))
+    ///     .enable_rbf();
+    /// let (psbt, tx_details) = tx_builder.finish()?;
+    /// # Ok::<(), bdk::Error>(())
+    /// ```
+    ///
+    /// [`allow_shrinking`]: Self::allow_shrinking
+    /// [`add_recipient`]: Self::add_recipient
+    /// [`drain_wallet`]: Self::drain_wallet
+    pub fn drain_to(&mut self, script_pubkey: Script) -> &mut Self {
+        self.params.drain_to = Some(script_pubkey);
         self
     }
 }
 
 // methods supported only by bump_fee
-impl<'a, B, D: BatchDatabase> TxBuilder<'a, B, D, DefaultCoinSelectionAlgorithm, BumpFee> {
-    /// Bump the fees of a transaction made with [`set_single_recipient`](Self::set_single_recipient)
+impl<'a, D: BatchDatabase> TxBuilder<'a, D, DefaultCoinSelectionAlgorithm, BumpFee> {
+    /// Explicitly tells the wallet that it is allowed to reduce the fee of the output matching this
+    /// `script_pubkey` in order to bump the transaction fee. Without specifying this the wallet
+    /// will attempt to find a change output to shrink instead.
     ///
-    /// Unless extra inputs are specified with [`add_utxo`], this flag will make
-    /// `bump_fee` reduce the value of the existing output, or fail if it would be consumed
-    /// entirely given the higher new fee rate.
+    /// **Note** that the output may shrink to below the dust limit and therefore be removed. If it is
+    /// preserved then it is currently not guaranteed to be in the same position as it was
+    /// originally.
     ///
-    /// If extra inputs are added and they are not entirely consumed in fees, a change output will not
-    /// be added; the existing output will simply grow in value.
-    ///
-    /// Fails if the transaction has more than one outputs.
-    ///
-    /// [`add_utxo`]: Self::add_utxo
-    pub fn maintain_single_recipient(&mut self) -> Result<&mut Self, Error> {
-        let mut recipients = self.params.recipients.drain(..).collect::<Vec<_>>();
-        if recipients.len() != 1 {
-            return Err(Error::SingleRecipientMultipleOutputs);
+    /// Returns an `Err` if `script_pubkey` can't be found among the recipients of the
+    /// transaction we are bumping.
+    pub fn allow_shrinking(&mut self, script_pubkey: Script) -> Result<&mut Self, Error> {
+        match self
+            .params
+            .recipients
+            .iter()
+            .position(|(recipient_script, _)| *recipient_script == script_pubkey)
+        {
+            Some(position) => {
+                self.params.recipients.remove(position);
+                self.params.drain_to = Some(script_pubkey);
+                Ok(self)
+            }
+            None => Err(Error::Generic(format!(
+                "{} was not in the original transaction",
+                script_pubkey
+            ))),
         }
-        self.params.single_recipient = Some(recipients.pop().unwrap().0);
-        Ok(self)
     }
 }
 

src/wallet/utils.rs

@@ -9,13 +9,11 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
+use bitcoin::blockdata::script::Script;
 use bitcoin::secp256k1::{All, Secp256k1};
 
 use miniscript::{MiniscriptKey, Satisfier, ToPublicKey};
 
-// De-facto standard "dust limit" (even though it should change based on the output type)
-pub const DUST_LIMIT_SATOSHI: u64 = 546;
-
 // MSB of the nSequence. If set there's no consensus-constraint, so it must be disabled when
 // spending using CSV in order to enforce CSV rules
 pub(crate) const SEQUENCE_LOCKTIME_DISABLE_FLAG: u32 = 1 << 31;
@@ -28,18 +26,19 @@ pub(crate) const SEQUENCE_LOCKTIME_MASK: u32 = 0x0000FFFF;
 // Threshold for nLockTime to be considered a block-height-based timelock rather than time-based
 pub(crate) const BLOCKS_TIMELOCK_THRESHOLD: u32 = 500000000;
 
-/// Trait to check if a value is below the dust limit
+/// Trait to check if a value is below the dust limit.
+/// We are performing dust value calculation for a given script public key using rust-bitcoin to
+/// keep it compatible with network dust rate
 // we implement this trait to make sure we don't mess up the comparison with off-by-one like a <
-// instead of a <= etc. The constant value for the dust limit is not public on purpose, to
-// encourage the usage of this trait.
+// instead of a <= etc.
 pub trait IsDust {
     /// Check whether or not a value is below dust limit
-    fn is_dust(&self) -> bool;
+    fn is_dust(&self, script: &Script) -> bool;
 }
 
 impl IsDust for u64 {
-    fn is_dust(&self) -> bool {
-        *self <= DUST_LIMIT_SATOSHI
+    fn is_dust(&self, script: &Script) -> bool {
+        *self < script.dust_value().as_sat()
     }
 }
 
@@ -138,47 +137,32 @@ impl<Pk: MiniscriptKey + ToPublicKey> Satisfier<Pk> for Older {
 
 pub(crate) type SecpCtx = Secp256k1<All>;
 
-pub struct ChunksIterator<I: Iterator> {
-    iter: I,
-    size: usize,
-}
-
-#[cfg(any(feature = "electrum", feature = "esplora"))]
-impl<I: Iterator> ChunksIterator<I> {
-    pub fn new(iter: I, size: usize) -> Self {
-        ChunksIterator { iter, size }
-    }
-}
-
-impl<I: Iterator> Iterator for ChunksIterator<I> {
-    type Item = Vec<<I as std::iter::Iterator>::Item>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        let mut v = Vec::new();
-        for _ in 0..self.size {
-            let e = self.iter.next();
-
-            match e {
-                None => break,
-                Some(val) => v.push(val),
-            }
-        }
-
-        if v.is_empty() {
-            return None;
-        }
-
-        Some(v)
-    }
-}
-
 #[cfg(test)]
 mod test {
     use super::{
-        check_nlocktime, check_nsequence_rbf, BLOCKS_TIMELOCK_THRESHOLD,
+        check_nlocktime, check_nsequence_rbf, IsDust, BLOCKS_TIMELOCK_THRESHOLD,
         SEQUENCE_LOCKTIME_TYPE_FLAG,
     };
+    use crate::bitcoin::Address;
     use crate::types::FeeRate;
+    use std::str::FromStr;
+
+    #[test]
+    fn test_is_dust() {
+        let script_p2pkh = Address::from_str("1GNgwA8JfG7Kc8akJ8opdNWJUihqUztfPe")
+            .unwrap()
+            .script_pubkey();
+        assert!(script_p2pkh.is_p2pkh());
+        assert!(545.is_dust(&script_p2pkh));
+        assert!(!546.is_dust(&script_p2pkh));
+
+        let script_p2wpkh = Address::from_str("bc1qxlh2mnc0yqwas76gqq665qkggee5m98t8yskd8")
+            .unwrap()
+            .script_pubkey();
+        assert!(script_p2wpkh.is_v0_p2wpkh());
+        assert!(293.is_dust(&script_p2wpkh));
+        assert!(!294.is_dust(&script_p2wpkh));
+    }
 
     #[test]
     fn test_fee_from_btc_per_kb() {

src/wallet/verify.rs

@@ -0,0 +1,185 @@
+// Bitcoin Dev Kit
+// Written in 2021 by Alekos Filini <alekos.filini@gmail.com>
+//
+// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Verify transactions against the consensus rules
+
+use std::collections::HashMap;
+use std::fmt;
+
+use bitcoin::consensus::serialize;
+use bitcoin::{OutPoint, Transaction, Txid};
+
+use crate::blockchain::Blockchain;
+use crate::database::Database;
+use crate::error::Error;
+
+/// Verify a transaction against the consensus rules
+///
+/// This function uses [`bitcoinconsensus`] to verify transactions by fetching the required data
+/// either from the [`Database`] or using the [`Blockchain`].
+///
+/// Depending on the [capabilities](crate::blockchain::Blockchain::get_capabilities) of the
+/// [`Blockchain`] backend, the method could fail when called with old "historical" transactions or
+/// with unconfirmed transactions that have been evicted from the backend's memory.
+pub fn verify_tx<D: Database, B: Blockchain>(
+    tx: &Transaction,
+    database: &D,
+    blockchain: &B,
+) -> Result<(), VerifyError> {
+    log::debug!("Verifying {}", tx.txid());
+
+    let serialized_tx = serialize(tx);
+    let mut tx_cache = HashMap::<_, Transaction>::new();
+
+    for (index, input) in tx.input.iter().enumerate() {
+        let prev_tx = if let Some(prev_tx) = tx_cache.get(&input.previous_output.txid) {
+            prev_tx.clone()
+        } else if let Some(prev_tx) = database.get_raw_tx(&input.previous_output.txid)? {
+            prev_tx
+        } else if let Some(prev_tx) = blockchain.get_tx(&input.previous_output.txid)? {
+            prev_tx
+        } else {
+            return Err(VerifyError::MissingInputTx(input.previous_output.txid));
+        };
+
+        let spent_output = prev_tx
+            .output
+            .get(input.previous_output.vout as usize)
+            .ok_or(VerifyError::InvalidInput(input.previous_output))?;
+
+        bitcoinconsensus::verify(
+            &spent_output.script_pubkey.to_bytes(),
+            spent_output.value,
+            &serialized_tx,
+            index,
+        )?;
+
+        // Since we have a local cache we might as well cache stuff from the db, as it will very
+        // likely decrease latency compared to reading from disk or performing an SQL query.
+        tx_cache.insert(prev_tx.txid(), prev_tx);
+    }
+
+    Ok(())
+}
+
+/// Error during validation of a tx agains the consensus rules
+#[derive(Debug)]
+pub enum VerifyError {
+    /// The transaction being spent is not available in the database or the blockchain client
+    MissingInputTx(Txid),
+    /// The transaction being spent doesn't have the requested output
+    InvalidInput(OutPoint),
+
+    /// Consensus error
+    Consensus(bitcoinconsensus::Error),
+
+    /// Generic error
+    ///
+    /// It has to be wrapped in a `Box` since `Error` has a variant that contains this enum
+    Global(Box<Error>),
+}
+
+impl fmt::Display for VerifyError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+impl std::error::Error for VerifyError {}
+
+impl From<Error> for VerifyError {
+    fn from(other: Error) -> Self {
+        VerifyError::Global(Box::new(other))
+    }
+}
+impl_error!(bitcoinconsensus::Error, Consensus, VerifyError);
+
+#[cfg(test)]
+mod test {
+    use std::collections::HashSet;
+
+    use bitcoin::consensus::encode::deserialize;
+    use bitcoin::hashes::hex::FromHex;
+    use bitcoin::{Transaction, Txid};
+
+    use crate::blockchain::{Blockchain, Capability, Progress};
+    use crate::database::{BatchDatabase, BatchOperations, MemoryDatabase};
+    use crate::FeeRate;
+
+    use super::*;
+
+    struct DummyBlockchain;
+
+    impl Blockchain for DummyBlockchain {
+        fn get_capabilities(&self) -> HashSet<Capability> {
+            Default::default()
+        }
+        fn setup<D: BatchDatabase, P: 'static + Progress>(
+            &self,
+            _database: &mut D,
+            _progress_update: P,
+        ) -> Result<(), Error> {
+            Ok(())
+        }
+        fn get_tx(&self, _txid: &Txid) -> Result<Option<Transaction>, Error> {
+            Ok(None)
+        }
+        fn broadcast(&self, _tx: &Transaction) -> Result<(), Error> {
+            Ok(())
+        }
+        fn get_height(&self) -> Result<u32, Error> {
+            Ok(42)
+        }
+        fn estimate_fee(&self, _target: usize) -> Result<FeeRate, Error> {
+            Ok(FeeRate::default_min_relay_fee())
+        }
+    }
+
+    #[test]
+    fn test_verify_fail_unsigned_tx() {
+        // https://blockstream.info/tx/95da344585fcf2e5f7d6cbf2c3df2dcce84f9196f7a7bb901a43275cd6eb7c3f
+        let prev_tx: Transaction = deserialize(&Vec::<u8>::from_hex("020000000101192dea5e66d444380e106f8e53acb171703f00d43fb6b3ae88ca5644bdb7e1000000006b48304502210098328d026ce138411f957966c1cf7f7597ccbb170f5d5655ee3e9f47b18f6999022017c3526fc9147830e1340e04934476a3d1521af5b4de4e98baf49ec4c072079e01210276f847f77ec8dd66d78affd3c318a0ed26d89dab33fa143333c207402fcec352feffffff023d0ac203000000001976a9144bfbaf6afb76cc5771bc6404810d1cc041a6933988aca4b956050000000017a91494d5543c74a3ee98e0cf8e8caef5dc813a0f34b48768cb0700").unwrap()).unwrap();
+        // https://blockstream.info/tx/aca326a724eda9a461c10a876534ecd5ae7b27f10f26c3862fb996f80ea2d45d
+        let signed_tx: Transaction = deserialize(&Vec::<u8>::from_hex("02000000013f7cebd65c27431a90bba7f796914fe8cc2ddfc3f2cbd6f7e5f2fc854534da95000000006b483045022100de1ac3bcdfb0332207c4a91f3832bd2c2915840165f876ab47c5f8996b971c3602201c6c053d750fadde599e6f5c4e1963df0f01fc0d97815e8157e3d59fe09ca30d012103699b464d1d8bc9e47d4fb1cdaa89a1c5783d68363c4dbc4b524ed3d857148617feffffff02836d3c01000000001976a914fc25d6d5c94003bf5b0c7b640a248e2c637fcfb088ac7ada8202000000001976a914fbed3d9b11183209a57999d54d59f67c019e756c88ac6acb0700").unwrap()).unwrap();
+
+        let mut database = MemoryDatabase::new();
+        let blockchain = DummyBlockchain;
+
+        let mut unsigned_tx = signed_tx.clone();
+        for input in &mut unsigned_tx.input {
+            input.script_sig = Default::default();
+            input.witness = Default::default();
+        }
+
+        let result = verify_tx(&signed_tx, &database, &blockchain);
+        assert!(result.is_err(), "Should fail with missing input tx");
+        assert!(
+            matches!(result, Err(VerifyError::MissingInputTx(txid)) if txid == prev_tx.txid()),
+            "Error should be a `MissingInputTx` error"
+        );
+
+        // insert the prev_tx
+        database.set_raw_tx(&prev_tx).unwrap();
+
+        let result = verify_tx(&unsigned_tx, &database, &blockchain);
+        assert!(result.is_err(), "Should fail since the TX is unsigned");
+        assert!(
+            matches!(result, Err(VerifyError::Consensus(_))),
+            "Error should be a `Consensus` error"
+        );
+
+        let result = verify_tx(&signed_tx, &database, &blockchain);
+        assert!(
+            result.is_ok(),
+            "Should work since the TX is correctly signed"
+        );
+    }
+}