Merge bitcoindevkit/bdk-ffi#296: Add Transaction struct, update PSBT and Blockchain to use it

8e54ada436f84fb5bbcd5f448b7fccc186387bb4 Add Transaction struct, update PSBT and Blockchain to use it (Steve Myers)

Pull request description:

  ### Description

  Add new `Transaction` structure that can be created from transaction consensus encoded bytes. Update `PartiallySignedTransaction.extract_tx()` to return a `Transaction` instead of a the transaction bytes. Update `Blockchain.broadcast()` to take a `Transaction` parameter.

  ### Notes to the reviewers

  Fixes #157.

  ### Changelog notice

  #### Added

  - New `Transaction` structure that can be created from or serialized to consensus encoded bytes.

  #### Changed

  - `PartiallySignedTransaction.extract_tx()` returns a `Transaction` instead of a the transaction bytes.
  - `Blockchain.broadcast()` takes a `Transaction` instead of a `PartiallySignedTransaction`.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

  #### New Features:

  * [ ] I've added tests for the new feature
  * [x] I've added docs for the new feature

  #### Bugfixes:

  * [ ] This pull request breaks the existing API
  * [ ] I've added tests to reproduce the issue which are now passing
  * [ ] I'm linking the issue being fixed by this PR

ACKs for top commit:
  thunderbiscuit:
    Tested ACK 8e54ada436f84fb5bbcd5f448b7fccc186387bb4. I ran a script using bdk-jvm and your test vector. Looks good! Another win for the LDK/BDK integration.

Tree-SHA512: f5bfdafad93f0b4ada0756a8e68bdb12f2de680d8ae8a5083dbbeded6fc314bd79c8913f0b7f01e2eb807676092777ad8bf9466996cd51fa9587b8bb53170ca8

api-docs/kotlin/src/main/kotlin/org/bitcoindevkit/bdk.kt

@@ -248,7 +248,7 @@ class Blockchain(
     config: BlockchainConfig
 ) {
     /** Broadcast a transaction. */
-    fun broadcast(psbt: PartiallySignedBitcoinTransaction) {}
+    fun broadcast(transaction: Transaction) {}
 
     /** Estimate the fee rate required to confirm a transaction in a given target of blocks. */
     fun estimateFee(target: ULong): FeeRate {}
@@ -260,6 +260,18 @@ class Blockchain(
     fun getBlockHash(height: UInt): String {}
 }
 
+/**
+ * A bitcoin transaction.
+ *
+ * @constructor Build a new Bitcoin Transaction.
+ *
+ * @param transactionBytes The transaction bytes, bitcoin consensus encoded.
+ */
+class Transaction(transactionBytes: List<UByte>) {
+    /** Return the transaction bytes, bitcoin consensus encoded. */
+    fun serialize(): List<UByte> {}
+}
+
 /**
  * A partially signed bitcoin transaction.
  *
@@ -274,8 +286,8 @@ class PartiallySignedBitcoinTransaction(psbtBase64: String) {
     /** Get the txid of the PSBT. */
     fun txid(): String {}
 
-    /** Return the transaction as bytes. */
-    fun extractTx(): List<UByte>
+    /** Extract the transaction. */
+    fun extractTx(): Transaction {}
 
     /**
      * Combines this PartiallySignedTransaction with another PSBT as described by BIP 174.

bdk-ffi/src/bdk.udl

@@ -162,7 +162,7 @@ interface Blockchain {
   constructor(BlockchainConfig config);
 
   [Throws=BdkError]
-  void broadcast([ByRef] PartiallySignedTransaction psbt);
+  void broadcast([ByRef] Transaction transaction);
 
   [Throws=BdkError]
   FeeRate estimate_fee(u64 target);
@@ -237,6 +237,13 @@ interface FeeRate {
   float as_sat_per_vb();
 };
 
+interface Transaction {
+   [Throws=BdkError]
+   constructor(sequence<u8> transaction_bytes);
+
+   sequence<u8> serialize();
+};
+
 interface PartiallySignedTransaction {
   [Throws=BdkError]
   constructor(string psbt_base64);
@@ -245,7 +252,7 @@ interface PartiallySignedTransaction {
 
   string txid();
 
-  sequence<u8> extract_tx();
+  Transaction extract_tx();
 
   [Throws=BdkError]
   PartiallySignedTransaction combine(PartiallySignedTransaction other);

bdk-ffi/src/blockchain.rs

@@ -1,5 +1,5 @@
 // use crate::BlockchainConfig;
-use crate::{BdkError, PartiallySignedTransaction};
+use crate::{BdkError, Transaction};
 use bdk::bitcoin::Network;
 use bdk::blockchain::any::{AnyBlockchain, AnyBlockchainConfig};
 use bdk::blockchain::rpc::Auth as BdkAuth;
@@ -60,9 +60,9 @@ impl Blockchain {
         self.blockchain_mutex.lock().expect("blockchain")
     }
 
-    pub(crate) fn broadcast(&self, psbt: &PartiallySignedTransaction) -> Result<(), BdkError> {
-        let tx = psbt.internal.lock().unwrap().clone().extract_tx();
-        self.get_blockchain().broadcast(&tx)
+    pub(crate) fn broadcast(&self, transaction: &Transaction) -> Result<(), BdkError> {
+        let tx = &transaction.internal;
+        self.get_blockchain().broadcast(tx)
     }
 
     pub(crate) fn estimate_fee(&self, target: u64) -> Result<Arc<FeeRate>, BdkError> {

bdk-ffi/src/lib.rs

@@ -15,7 +15,11 @@ use crate::keys::{DescriptorPublicKey, DescriptorSecretKey, Mnemonic};
 use crate::psbt::PartiallySignedTransaction;
 use crate::wallet::{BumpFeeTxBuilder, TxBuilder, Wallet};
 use bdk::bitcoin::blockdata::script::Script as BdkScript;
-use bdk::bitcoin::{Address as BdkAddress, Network, OutPoint as BdkOutPoint, Txid};
+use bdk::bitcoin::consensus::Decodable;
+use bdk::bitcoin::psbt::serialize::Serialize;
+use bdk::bitcoin::{
+    Address as BdkAddress, Network, OutPoint as BdkOutPoint, Transaction as BdkTransaction, Txid,
+};
 use bdk::blockchain::Progress as BdkProgress;
 use bdk::database::any::{SledDbConfiguration, SqliteDbConfiguration};
 use bdk::keys::bip39::WordCount;
@@ -24,6 +28,7 @@ use bdk::wallet::AddressInfo as BdkAddressInfo;
 use bdk::{Balance as BdkBalance, BlockTime, Error as BdkError, FeeRate, KeychainKind};
 use std::convert::From;
 use std::fmt;
+use std::io::Cursor;
 use std::str::FromStr;
 use std::sync::Arc;
 
@@ -218,6 +223,24 @@ impl fmt::Debug for ProgressHolder {
     }
 }
 
+/// A Bitcoin transaction.
+#[derive(Debug)]
+pub struct Transaction {
+    internal: BdkTransaction,
+}
+
+impl Transaction {
+    fn new(transaction_bytes: Vec<u8>) -> Result<Self, BdkError> {
+        let mut decoder = Cursor::new(transaction_bytes);
+        let tx: BdkTransaction = BdkTransaction::consensus_decode(&mut decoder)?;
+        Ok(Transaction { internal: tx })
+    }
+
+    fn serialize(&self) -> Vec<u8> {
+        self.internal.serialize()
+    }
+}
+
 /// A Bitcoin address.
 struct Address {
     address: BdkAddress,
@@ -264,3 +287,21 @@ pub struct TxBuilderResult {
 }
 
 uniffi::deps::static_assertions::assert_impl_all!(Wallet: Sync, Send);
+
+// The goal of these tests to to ensure `bdk-ffi` intermediate code correctly calls `bdk` APIs.
+// These tests should not be used to verify `bdk` behavior that is already tested in the `bdk`
+// crate.
+#[cfg(test)]
+mod test {
+    use super::Transaction;
+    use bdk::bitcoin::hashes::hex::FromHex;
+
+    // Verify that bdk-ffi Transaction can be created from valid bytes and serialized back into the same bytes.
+    #[test]
+    fn test_transaction_serde() {
+        let test_tx_bytes = Vec::from_hex("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").unwrap();
+        let new_tx_from_bytes = Transaction::new(test_tx_bytes.clone()).unwrap();
+        let serialized_tx_to_bytes = new_tx_from_bytes.serialize();
+        assert_eq!(test_tx_bytes, serialized_tx_to_bytes);
+    }
+}

bdk-ffi/src/psbt.rs

@@ -1,11 +1,10 @@
 use bdk::bitcoin::hashes::hex::ToHex;
-use bdk::bitcoin::psbt::serialize::Serialize;
 use bdk::bitcoin::util::psbt::PartiallySignedTransaction as BdkPartiallySignedTransaction;
 use bdk::psbt::PsbtUtils;
 use std::str::FromStr;
 use std::sync::{Arc, Mutex};
 
-use crate::{BdkError, FeeRate};
+use crate::{BdkError, FeeRate, Transaction};
 
 #[derive(Debug)]
 pub(crate) struct PartiallySignedTransaction {
@@ -32,14 +31,10 @@ impl PartiallySignedTransaction {
         txid.to_hex()
     }
 
-    /// Return the transaction as bytes.
-    pub(crate) fn extract_tx(&self) -> Vec<u8> {
-        self.internal
-            .lock()
-            .unwrap()
-            .clone()
-            .extract_tx()
-            .serialize()
+    /// Return the transaction.
+    pub(crate) fn extract_tx(&self) -> Arc<Transaction> {
+        let tx = self.internal.lock().unwrap().clone().extract_tx();
+        Arc::new(Transaction { internal: tx })
     }
 
     /// Combines this PartiallySignedTransaction with other PSBT as described by BIP 174.