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// 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.
//! Transaction builder
//!
//! ## Example
//!
//! ```
//! # use std::str::FromStr;
//! # use bitcoin::*;
//! # use bdk_wallet::*;
//! # use bdk_wallet::ChangeSet;
//! # use bdk_wallet::error::CreateTxError;
//! # use anyhow::Error;
//! # let to_address = Address::from_str("2N4eQYCbKUHCCTUjBJeHcJp9ok6J2GZsTDt").unwrap().assume_checked();
//! # let mut wallet = doctest_wallet!();
//! // create a TxBuilder from a wallet
//! let mut tx_builder = wallet.build_tx();
//!
//! tx_builder
//! // Create a transaction with one output to `to_address` of 50_000 satoshi
//! .add_recipient(to_address.script_pubkey(), Amount::from_sat(50_000))
//! // With a custom fee rate of 5.0 satoshi/vbyte
//! .fee_rate(FeeRate::from_sat_per_vb(5).expect("valid feerate"))
//! // Only spend non-change outputs
//! .do_not_spend_change();
//! let psbt = tx_builder.finish()?;
//! # Ok::<(), anyhow::Error>(())
//! ```
use alloc::{boxed::Box, rc::Rc, string::String, vec::Vec};
use core::cell::RefCell;
use core::fmt;
use alloc::sync::Arc;
use bitcoin::psbt::{self, Psbt};
use bitcoin::script::PushBytes;
use bitcoin::{
absolute, Amount, FeeRate, OutPoint, ScriptBuf, Sequence, Transaction, TxIn, TxOut, Txid,
Weight,
};
use rand_core::RngCore;
use super::coin_selection::CoinSelectionAlgorithm;
use super::utils::shuffle_slice;
use super::{CreateTxError, Wallet};
use crate::collections::{BTreeMap, HashSet};
use crate::{KeychainKind, LocalOutput, Utxo, WeightedUtxo};
/// A transaction builder
///
/// A `TxBuilder` is created by calling [`build_tx`] or [`build_fee_bump`] on a wallet. After
/// assigning it, you set options on it until finally calling [`finish`] to consume the builder and
/// generate the transaction.
///
/// Each option setting method on `TxBuilder` takes and returns `&mut self` so you can chain calls
/// as in the following example:
///
/// ```
/// # use bdk_wallet::*;
/// # use bdk_wallet::tx_builder::*;
/// # use bitcoin::*;
/// # use core::str::FromStr;
/// # use bdk_wallet::ChangeSet;
/// # use bdk_wallet::error::CreateTxError;
/// # use anyhow::Error;
/// # let mut wallet = doctest_wallet!();
/// # let addr1 = Address::from_str("2N4eQYCbKUHCCTUjBJeHcJp9ok6J2GZsTDt").unwrap().assume_checked();
/// # let addr2 = addr1.clone();
/// // chaining
/// let psbt1 = {
/// let mut builder = wallet.build_tx();
/// builder
/// .ordering(TxOrdering::Untouched)
/// .add_recipient(addr1.script_pubkey(), Amount::from_sat(50_000))
/// .add_recipient(addr2.script_pubkey(), Amount::from_sat(50_000));
/// builder.finish()?
/// };
///
/// // non-chaining
/// let psbt2 = {
/// let mut builder = wallet.build_tx();
/// builder.ordering(TxOrdering::Untouched);
/// for addr in &[addr1, addr2] {
/// builder.add_recipient(addr.script_pubkey(), Amount::from_sat(50_000));
/// }
/// builder.finish()?
/// };
///
/// assert_eq!(psbt1.unsigned_tx.output[..2], psbt2.unsigned_tx.output[..2]);
/// # Ok::<(), anyhow::Error>(())
/// ```
///
/// At the moment [`coin_selection`] is an exception to the rule as it consumes `self`.
/// This means it is usually best to call [`coin_selection`] on the return value of `build_tx` before assigning it.
///
/// For further examples see [this module](super::tx_builder)'s documentation;
///
/// [`build_tx`]: Wallet::build_tx
/// [`build_fee_bump`]: Wallet::build_fee_bump
/// [`finish`]: Self::finish
/// [`coin_selection`]: Self::coin_selection
#[derive(Debug)]
pub struct TxBuilder<'a, Cs> {
pub(crate) wallet: Rc<RefCell<&'a mut Wallet>>,
pub(crate) params: TxParams,
pub(crate) coin_selection: Cs,
}
/// The parameters for transaction creation sans coin selection algorithm.
//TODO: TxParams should eventually be exposed publicly.
#[derive(Default, Debug, Clone)]
pub(crate) struct TxParams {
pub(crate) recipients: Vec<(ScriptBuf, Amount)>,
pub(crate) drain_wallet: bool,
pub(crate) drain_to: Option<ScriptBuf>,
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>>>,
pub(crate) utxos: Vec<WeightedUtxo>,
pub(crate) unspendable: HashSet<OutPoint>,
pub(crate) manually_selected_only: bool,
pub(crate) sighash: Option<psbt::PsbtSighashType>,
pub(crate) ordering: TxOrdering,
pub(crate) locktime: Option<absolute::LockTime>,
pub(crate) sequence: Option<Sequence>,
pub(crate) version: Option<Version>,
pub(crate) change_policy: ChangeSpendPolicy,
pub(crate) only_witness_utxo: bool,
pub(crate) add_global_xpubs: bool,
pub(crate) include_output_redeem_witness_script: bool,
pub(crate) bumping_fee: Option<PreviousFee>,
pub(crate) current_height: Option<absolute::LockTime>,
pub(crate) allow_dust: bool,
}
#[derive(Clone, Copy, Debug)]
pub(crate) struct PreviousFee {
pub absolute: Amount,
pub rate: FeeRate,
}
#[derive(Debug, Clone, Copy)]
pub(crate) enum FeePolicy {
FeeRate(FeeRate),
FeeAmount(Amount),
}
impl Default for FeePolicy {
fn default() -> Self {
FeePolicy::FeeRate(FeeRate::BROADCAST_MIN)
}
}
impl<'a, Cs: Clone> Clone for TxBuilder<'a, Cs> {
fn clone(&self) -> Self {
TxBuilder {
wallet: self.wallet.clone(),
params: self.params.clone(),
coin_selection: self.coin_selection.clone(),
}
}
}
// Methods supported for any CoinSelectionAlgorithm.
impl<'a, Cs> TxBuilder<'a, Cs> {
/// Set a custom fee rate.
///
/// This method sets the mining fee paid by the transaction as a rate on its size.
/// This means that the total fee paid is equal to `fee_rate` times the size
/// of the transaction. Default is 1 sat/vB in accordance with Bitcoin Core's default
/// relay policy.
///
/// Note that this is really a minimum feerate -- it's possible to
/// overshoot it slightly since adding a change output to drain the remaining
/// excess might not be viable.
pub fn fee_rate(&mut self, fee_rate: FeeRate) -> &mut Self {
self.params.fee_policy = Some(FeePolicy::FeeRate(fee_rate));
self
}
/// Set an absolute fee
/// The fee_absolute method refers to the absolute transaction fee in [`Amount`].
/// If anyone sets both the `fee_absolute` method and the `fee_rate` method,
/// the `FeePolicy` enum will be set by whichever method was called last,
/// as the [`FeeRate`] and `FeeAmount` are mutually exclusive.
///
/// Note that this is really a minimum absolute fee -- it's possible to
/// overshoot it slightly since adding a change output to drain the remaining
/// excess might not be viable.
pub fn fee_absolute(&mut self, fee_amount: Amount) -> &mut Self {
self.params.fee_policy = Some(FeePolicy::FeeAmount(fee_amount));
self
}
/// Set the policy path to use while creating the transaction for a given keychain.
///
/// This method accepts a map where the key is the policy node id (see
/// [`Policy::id`](crate::descriptor::Policy::id)) and the value is the list of the indexes of
/// the items that are intended to be satisfied from the policy node (see
/// [`SatisfiableItem::Thresh::items`](crate::descriptor::policy::SatisfiableItem::Thresh::items)).
///
/// ## Example
///
/// An example of when the policy path is needed is the following descriptor:
/// `wsh(thresh(2,pk(A),sj:and_v(v:pk(B),n:older(6)),snj:and_v(v:pk(C),after(630000))))`,
/// derived from the miniscript policy `thresh(2,pk(A),and(pk(B),older(6)),and(pk(C),after(630000)))`.
/// It declares three descriptor fragments, and at the top level it uses `thresh()` to
/// ensure that at least two of them are satisfied. The individual fragments are:
///
/// 1. `pk(A)`
/// 2. `and(pk(B),older(6))`
/// 3. `and(pk(C),after(630000))`
///
/// When those conditions are combined in pairs, it's clear that the transaction needs to be created
/// differently depending on how the user intends to satisfy the policy afterwards:
///
/// * If fragments `1` and `2` are used, the transaction will need to use a specific
/// `n_sequence` in order to spend an `OP_CSV` branch.
/// * If fragments `1` and `3` are used, the transaction will need to use a specific `locktime`
/// in order to spend an `OP_CLTV` branch.
/// * If fragments `2` and `3` are used, the transaction will need both.
///
/// When the spending policy is represented as a tree (see
/// [`Wallet::policies`](super::Wallet::policies)), every node
/// is assigned a unique identifier that can be used in the policy path to specify which of
/// the node's children the user intends to satisfy: for instance, assuming the `thresh()`
/// root node of this example has an id of `aabbccdd`, the policy path map would look like:
///
/// `{ "aabbccdd" => [0, 1] }`
///
/// where the key is the node's id, and the value is a list of the children that should be
/// used, in no particular order.
///
/// If a particularly complex descriptor has multiple ambiguous thresholds in its structure,
/// multiple entries can be added to the map, one for each node that requires an explicit path.
///
/// ```
/// # use std::str::FromStr;
/// # use std::collections::BTreeMap;
/// # use bitcoin::*;
/// # use bdk_wallet::*;
/// # let to_address =
/// Address::from_str("2N4eQYCbKUHCCTUjBJeHcJp9ok6J2GZsTDt")
/// .unwrap()
/// .assume_checked();
/// # let mut wallet = doctest_wallet!();
/// let mut path = BTreeMap::new();
/// path.insert("aabbccdd".to_string(), vec![0, 1]);
///
/// let builder = wallet
/// .build_tx()
/// .add_recipient(to_address.script_pubkey(), Amount::from_sat(50_000))
/// .policy_path(path, KeychainKind::External);
///
/// # Ok::<(), anyhow::Error>(())
/// ```
pub fn policy_path(
&mut self,
policy_path: BTreeMap<String, Vec<usize>>,
keychain: KeychainKind,
) -> &mut Self {
let to_update = match keychain {
KeychainKind::Internal => &mut self.params.internal_policy_path,
KeychainKind::External => &mut self.params.external_policy_path,
};
*to_update = Some(policy_path);
self
}
/// Add the list of outpoints to the internal list of UTXOs that **must** be spent.
///
/// If an error occurs while adding any of the UTXOs then none of them are added and the error is returned.
///
/// These have priority over the "unspendable" utxos, meaning that if a utxo is present both in
/// the "utxos" and the "unspendable" list, it will be spent.
pub fn add_utxos(&mut self, outpoints: &[OutPoint]) -> Result<&mut Self, AddUtxoError> {
{
let wallet = self.wallet.borrow();
let utxos = outpoints
.iter()
.map(|outpoint| {
wallet
.get_utxo(*outpoint)
.ok_or(AddUtxoError::UnknownUtxo(*outpoint))
})
.collect::<Result<Vec<_>, _>>()?;
for utxo in utxos {
let descriptor = wallet.public_descriptor(utxo.keychain);
let satisfaction_weight = descriptor.max_weight_to_satisfy().unwrap();
self.params.utxos.push(WeightedUtxo {
satisfaction_weight,
utxo: Utxo::Local(utxo),
});
}
}
Ok(self)
}
/// Add a utxo to the internal list of utxos that **must** be spent
///
/// These have priority over the "unspendable" utxos, meaning that if a utxo is present both in
/// the "utxos" and the "unspendable" list, it will be spent.
pub fn add_utxo(&mut self, outpoint: OutPoint) -> Result<&mut Self, AddUtxoError> {
self.add_utxos(&[outpoint])
}
/// Add a foreign UTXO i.e. a UTXO not owned by this wallet.
///
/// At a minimum to add a foreign UTXO we need:
///
/// 1. `outpoint`: To add it to the raw transaction.
/// 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 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
/// method doesn't verify the value but just takes it as a given -- it is up to you to check
/// that whoever sent you the `input_psbt` was not lying!
///
/// Secondly, you must somehow provide `satisfaction_weight` of the input. Depending on your
/// application it may be important that this be known precisely. If not, a malicious
/// counterparty may fool you into putting in a value that is too low, giving the transaction a
/// lower than expected feerate. They could also fool you into putting a value that is too high
/// causing you to pay a fee that is too high. The party who is broadcasting the transaction can
/// of course check the real input weight matches the expected weight prior to broadcasting.
///
/// To guarantee the `max_weight_to_satisfy` is correct, you can require the party providing the
/// `psbt_input` provide a miniscript descriptor for the input so you can check it against the
/// `script_pubkey` and then ask it for the [`max_weight_to_satisfy`].
///
/// This is an **EXPERIMENTAL** feature, API and other major changes are expected.
///
/// In order to use [`Wallet::calculate_fee`] or [`Wallet::calculate_fee_rate`] for a transaction
/// created with foreign UTXO(s) you must manually insert the corresponding TxOut(s) into the tx
/// graph using the [`Wallet::insert_txout`] function.
///
/// # Errors
///
/// This method returns errors in the following circumstances:
///
/// 1. The `psbt_input` does not contain a `witness_utxo` or `non_witness_utxo`.
/// 2. The data in `non_witness_utxo` does not match what is in `outpoint`.
///
/// Note unless you set [`only_witness_utxo`] any non-taproot `psbt_input` you pass to this
/// method must have `non_witness_utxo` set otherwise you will get an error when [`finish`]
/// is called.
///
/// [`only_witness_utxo`]: Self::only_witness_utxo
/// [`finish`]: Self::finish
/// [`max_weight_to_satisfy`]: miniscript::Descriptor::max_weight_to_satisfy
pub fn add_foreign_utxo(
&mut self,
outpoint: OutPoint,
psbt_input: psbt::Input,
satisfaction_weight: Weight,
) -> Result<&mut Self, AddForeignUtxoError> {
self.add_foreign_utxo_with_sequence(
outpoint,
psbt_input,
satisfaction_weight,
Sequence::MAX,
)
}
/// Same as [add_foreign_utxo](TxBuilder::add_foreign_utxo) but allows to set the nSequence value.
pub fn add_foreign_utxo_with_sequence(
&mut self,
outpoint: OutPoint,
psbt_input: psbt::Input,
satisfaction_weight: Weight,
sequence: Sequence,
) -> Result<&mut Self, AddForeignUtxoError> {
if psbt_input.witness_utxo.is_none() {
match psbt_input.non_witness_utxo.as_ref() {
Some(tx) => {
if tx.compute_txid() != outpoint.txid {
return Err(AddForeignUtxoError::InvalidTxid {
input_txid: tx.compute_txid(),
foreign_utxo: outpoint,
});
}
if tx.output.len() <= outpoint.vout as usize {
return Err(AddForeignUtxoError::InvalidOutpoint(outpoint));
}
}
None => {
return Err(AddForeignUtxoError::MissingUtxo);
}
}
}
self.params.utxos.push(WeightedUtxo {
satisfaction_weight,
utxo: Utxo::Foreign {
outpoint,
sequence: Some(sequence),
psbt_input: Box::new(psbt_input),
},
});
Ok(self)
}
/// Only spend utxos added by [`add_utxo`].
///
/// The wallet will **not** add additional utxos to the transaction even if they are needed to
/// make the transaction valid.
///
/// [`add_utxo`]: Self::add_utxo
pub fn manually_selected_only(&mut self) -> &mut Self {
self.params.manually_selected_only = true;
self
}
/// Replace the internal list of unspendable utxos with a new list
///
/// It's important to note that the "must-be-spent" utxos added with [`TxBuilder::add_utxo`]
/// have priority over these. See the docs of the two linked methods for more details.
pub fn unspendable(&mut self, unspendable: Vec<OutPoint>) -> &mut Self {
self.params.unspendable = unspendable.into_iter().collect();
self
}
/// Add a utxo to the internal list of unspendable utxos
///
/// It's important to note that the "must-be-spent" utxos added with [`TxBuilder::add_utxo`]
/// have priority over this. See the docs of the two linked methods for more details.
pub fn add_unspendable(&mut self, unspendable: OutPoint) -> &mut Self {
self.params.unspendable.insert(unspendable);
self
}
/// Sign with a specific sig hash
///
/// **Use this option very carefully**
pub fn sighash(&mut self, sighash: psbt::PsbtSighashType) -> &mut Self {
self.params.sighash = Some(sighash);
self
}
/// Choose the ordering for inputs and outputs of the transaction
pub fn ordering(&mut self, ordering: TxOrdering) -> &mut Self {
self.params.ordering = ordering;
self
}
/// Use a specific nLockTime while creating the transaction
///
/// This can cause conflicts if the wallet's descriptors contain an "after" (OP_CLTV) operator.
pub fn nlocktime(&mut self, locktime: absolute::LockTime) -> &mut Self {
self.params.locktime = Some(locktime);
self
}
/// Build a transaction with a specific version
///
/// The `version` should always be greater than `0` and greater than `1` if the wallet's
/// descriptors contain an "older" (OP_CSV) operator.
pub fn version(&mut self, version: i32) -> &mut Self {
self.params.version = Some(Version(version));
self
}
/// Do not spend change outputs
///
/// This effectively adds all the change outputs to the "unspendable" list. See
/// [`TxBuilder::unspendable`]. This method assumes the presence of an internal
/// keychain, otherwise it has no effect.
pub fn do_not_spend_change(&mut self) -> &mut Self {
self.params.change_policy = ChangeSpendPolicy::ChangeForbidden;
self
}
/// Only spend change outputs
///
/// This effectively adds all the non-change outputs to the "unspendable" list. See
/// [`TxBuilder::unspendable`]. This method assumes the presence of an internal
/// keychain, otherwise it has no effect.
pub fn only_spend_change(&mut self) -> &mut Self {
self.params.change_policy = ChangeSpendPolicy::OnlyChange;
self
}
/// Set a specific [`ChangeSpendPolicy`]. See [`TxBuilder::do_not_spend_change`] and
/// [`TxBuilder::only_spend_change`] for some shortcuts. This method assumes the presence
/// of an internal keychain, otherwise it has no effect.
pub fn change_policy(&mut self, change_policy: ChangeSpendPolicy) -> &mut Self {
self.params.change_policy = change_policy;
self
}
/// Only Fill-in the [`psbt::Input::witness_utxo`](bitcoin::psbt::Input::witness_utxo) field when spending from
/// SegWit descriptors.
///
/// This reduces the size of the PSBT, but some signers might reject them due to the lack of
/// the `non_witness_utxo`.
pub fn only_witness_utxo(&mut self) -> &mut Self {
self.params.only_witness_utxo = true;
self
}
/// Fill-in the [`psbt::Output::redeem_script`](bitcoin::psbt::Output::redeem_script) and
/// [`psbt::Output::witness_script`](bitcoin::psbt::Output::witness_script) fields.
///
/// This is useful for signers which always require it, like ColdCard hardware wallets.
pub fn include_output_redeem_witness_script(&mut self) -> &mut Self {
self.params.include_output_redeem_witness_script = true;
self
}
/// Fill-in the `PSBT_GLOBAL_XPUB` field with the extended keys contained in both the external
/// and internal descriptors
///
/// This is useful for offline signers that take part to a multisig. Some hardware wallets like
/// BitBox and ColdCard are known to require this.
pub fn add_global_xpubs(&mut self) -> &mut Self {
self.params.add_global_xpubs = true;
self
}
/// Spend all the available inputs. This respects filters like [`TxBuilder::unspendable`] and the change policy.
pub fn drain_wallet(&mut self) -> &mut Self {
self.params.drain_wallet = true;
self
}
/// Choose the coin selection algorithm
///
/// Overrides the [`CoinSelectionAlgorithm`].
///
/// Note that this function consumes the builder and returns it so it is usually best to put this as the first call on the builder.
pub fn coin_selection<P: CoinSelectionAlgorithm>(self, coin_selection: P) -> TxBuilder<'a, P> {
TxBuilder {
wallet: self.wallet,
params: self.params,
coin_selection,
}
}
/// Set an exact nSequence value
///
/// This can cause conflicts if the wallet's descriptors contain an
/// "older" (OP_CSV) operator and the given `nsequence` is lower than the CSV value.
pub fn set_exact_sequence(&mut self, n_sequence: Sequence) -> &mut Self {
self.params.sequence = Some(n_sequence);
self
}
/// Set the current blockchain height.
///
/// This will be used to:
/// 1. Set the nLockTime for preventing fee sniping.
/// **Note**: This will be ignored if you manually specify a nlocktime using [`TxBuilder::nlocktime`].
/// 2. Decide whether coinbase outputs are mature or not. If the coinbase outputs are not
/// mature at `current_height`, we ignore them in the coin selection.
/// If you want to create a transaction that spends immature coinbase inputs, manually
/// add them using [`TxBuilder::add_utxos`].
///
/// In both cases, if you don't provide a current height, we use the last sync height.
pub fn current_height(&mut self, height: u32) -> &mut Self {
self.params.current_height =
Some(absolute::LockTime::from_height(height).expect("Invalid height"));
self
}
/// Set whether or not the dust limit is checked.
///
/// **Note**: by avoiding a dust limit check you may end up with a transaction that is non-standard.
pub fn allow_dust(&mut self, allow_dust: bool) -> &mut Self {
self.params.allow_dust = allow_dust;
self
}
/// Replace the recipients already added with a new list
pub fn set_recipients(&mut self, recipients: Vec<(ScriptBuf, Amount)>) -> &mut Self {
self.params.recipients = recipients;
self
}
/// Add a recipient to the internal list
pub fn add_recipient(&mut self, script_pubkey: ScriptBuf, amount: Amount) -> &mut Self {
self.params.recipients.push((script_pubkey, amount));
self
}
/// Add data as an output, using OP_RETURN
pub fn add_data<T: AsRef<PushBytes>>(&mut self, data: &T) -> &mut Self {
let script = ScriptBuf::new_op_return(data);
self.add_recipient(script, Amount::ZERO);
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).
///
/// If you choose not to set any recipients, you should provide the utxos that the
/// transaction should spend via [`add_utxos`].
///
/// # 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_wallet::*;
/// # use bdk_wallet::ChangeSet;
/// # use bdk_wallet::error::CreateTxError;
/// # use anyhow::Error;
/// # let to_address =
/// Address::from_str("2N4eQYCbKUHCCTUjBJeHcJp9ok6J2GZsTDt")
/// .unwrap()
/// .assume_checked();
/// # let mut 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).expect("valid feerate"));
/// let psbt = tx_builder.finish()?;
/// # Ok::<(), anyhow::Error>(())
/// ```
///
/// [`add_recipient`]: Self::add_recipient
/// [`add_utxos`]: Self::add_utxos
/// [`drain_wallet`]: Self::drain_wallet
pub fn drain_to(&mut self, script_pubkey: ScriptBuf) -> &mut Self {
self.params.drain_to = Some(script_pubkey);
self
}
}
impl<'a, Cs: CoinSelectionAlgorithm> TxBuilder<'a, Cs> {
/// Finish building the transaction.
///
/// Uses the thread-local random number generator (rng).
///
/// Returns a new [`Psbt`] per [`BIP174`].
///
/// [`BIP174`]: https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki
///
/// **WARNING**: To avoid change address reuse you must persist the changes resulting from one
/// or more calls to this method before closing the wallet. See [`Wallet::reveal_next_address`].
#[cfg(feature = "std")]
pub fn finish(self) -> Result<Psbt, CreateTxError> {
self.finish_with_aux_rand(&mut bitcoin::key::rand::thread_rng())
}
/// Finish building the transaction.
///
/// Uses a provided random number generator (rng).
///
/// Returns a new [`Psbt`] per [`BIP174`].
///
/// [`BIP174`]: https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki
///
/// **WARNING**: To avoid change address reuse you must persist the changes resulting from one
/// or more calls to this method before closing the wallet. See [`Wallet::reveal_next_address`].
pub fn finish_with_aux_rand(self, rng: &mut impl RngCore) -> Result<Psbt, CreateTxError> {
self.wallet
.borrow_mut()
.create_tx(self.coin_selection, self.params, rng)
}
}
#[derive(Debug)]
/// Error returned from [`TxBuilder::add_utxo`] and [`TxBuilder::add_utxos`]
pub enum AddUtxoError {
/// Happens when trying to spend an UTXO that is not in the internal database
UnknownUtxo(OutPoint),
}
impl fmt::Display for AddUtxoError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::UnknownUtxo(outpoint) => write!(
f,
"UTXO not found in the internal database for txid: {} with vout: {}",
outpoint.txid, outpoint.vout
),
}
}
}
#[cfg(feature = "std")]
impl std::error::Error for AddUtxoError {}
#[derive(Debug)]
/// Error returned from [`TxBuilder::add_foreign_utxo`].
pub enum AddForeignUtxoError {
/// Foreign utxo outpoint txid does not match PSBT input txid
InvalidTxid {
/// PSBT input txid
input_txid: Txid,
/// Foreign UTXO outpoint
foreign_utxo: OutPoint,
},
/// Requested outpoint doesn't exist in the tx (vout greater than available outputs)
InvalidOutpoint(OutPoint),
/// Foreign utxo missing witness_utxo or non_witness_utxo
MissingUtxo,
}
impl fmt::Display for AddForeignUtxoError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::InvalidTxid {
input_txid,
foreign_utxo,
} => write!(
f,
"Foreign UTXO outpoint txid: {} does not match PSBT input txid: {}",
foreign_utxo.txid, input_txid,
),
Self::InvalidOutpoint(outpoint) => write!(
f,
"Requested outpoint doesn't exist for txid: {} with vout: {}",
outpoint.txid, outpoint.vout,
),
Self::MissingUtxo => write!(f, "Foreign utxo missing witness_utxo or non_witness_utxo"),
}
}
}
#[cfg(feature = "std")]
impl std::error::Error for AddForeignUtxoError {}
type TxSort<T> = dyn Fn(&T, &T) -> core::cmp::Ordering;
/// Ordering of the transaction's inputs and outputs
#[derive(Clone, Default)]
pub enum TxOrdering {
/// Randomized (default)
#[default]
Shuffle,
/// Unchanged
Untouched,
/// Provide custom comparison functions for sorting
Custom {
/// Transaction inputs sort function
input_sort: Arc<TxSort<TxIn>>,
/// Transaction outputs sort function
output_sort: Arc<TxSort<TxOut>>,
},
}
impl core::fmt::Debug for TxOrdering {
fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
match self {
TxOrdering::Shuffle => write!(f, "Shuffle"),
TxOrdering::Untouched => write!(f, "Untouched"),
TxOrdering::Custom { .. } => write!(f, "Custom"),
}
}
}
impl TxOrdering {
/// Sort transaction inputs and outputs by [`TxOrdering`] variant.
///
/// Uses the thread-local random number generator (rng).
#[cfg(feature = "std")]
pub fn sort_tx(&self, tx: &mut Transaction) {
self.sort_tx_with_aux_rand(tx, &mut bitcoin::key::rand::thread_rng())
}
/// Sort transaction inputs and outputs by [`TxOrdering`] variant.
///
/// Uses a provided random number generator (rng).
pub fn sort_tx_with_aux_rand(&self, tx: &mut Transaction, rng: &mut impl RngCore) {
match self {
TxOrdering::Untouched => {}
TxOrdering::Shuffle => {
shuffle_slice(&mut tx.input, rng);
shuffle_slice(&mut tx.output, rng);
}
TxOrdering::Custom {
input_sort,
output_sort,
} => {
tx.input.sort_unstable_by(|a, b| input_sort(a, b));
tx.output.sort_unstable_by(|a, b| output_sort(a, b));
}
}
}
}
/// Transaction version
///
/// Has a default value of `1`
#[derive(Debug, Ord, PartialOrd, Eq, PartialEq, Hash, Clone, Copy)]
pub(crate) struct Version(pub(crate) i32);
impl Default for Version {
fn default() -> Self {
Version(1)
}
}
/// Policy regarding the use of change outputs when creating a transaction
#[derive(Default, Debug, Ord, PartialOrd, Eq, PartialEq, Hash, Clone, Copy)]
pub enum ChangeSpendPolicy {
/// Use both change and non-change outputs (default)
#[default]
ChangeAllowed,
/// Only use change outputs (see [`TxBuilder::only_spend_change`])
OnlyChange,
/// Only use non-change outputs (see [`TxBuilder::do_not_spend_change`])
ChangeForbidden,
}
impl ChangeSpendPolicy {
pub(crate) fn is_satisfied_by(&self, utxo: &LocalOutput) -> bool {
match self {
ChangeSpendPolicy::ChangeAllowed => true,
ChangeSpendPolicy::OnlyChange => utxo.keychain == KeychainKind::Internal,
ChangeSpendPolicy::ChangeForbidden => utxo.keychain == KeychainKind::External,
}
}
}
#[cfg(test)]
mod test {
const ORDERING_TEST_TX: &str = "0200000003c26f3eb7932f7acddc5ddd26602b77e7516079b03090a16e2c2f54\
85d1fd600f0100000000ffffffffc26f3eb7932f7acddc5ddd26602b77e75160\
79b03090a16e2c2f5485d1fd600f0000000000ffffffff571fb3e02278217852\
dd5d299947e2b7354a639adc32ec1fa7b82cfb5dec530e0500000000ffffffff\
03e80300000000000002aaeee80300000000000001aa200300000000000001ff\
00000000";
macro_rules! ordering_test_tx {
() => {
deserialize::<bitcoin::Transaction>(&Vec::<u8>::from_hex(ORDERING_TEST_TX).unwrap())
.unwrap()
};
}
use bdk_chain::ConfirmationTime;
use bitcoin::consensus::deserialize;
use bitcoin::hex::FromHex;
use bitcoin::TxOut;
use super::*;
#[test]
fn test_output_ordering_untouched() {
let original_tx = ordering_test_tx!();
let mut tx = original_tx.clone();
TxOrdering::Untouched.sort_tx(&mut tx);
assert_eq!(original_tx, tx);
}
#[test]
fn test_output_ordering_shuffle() {
let original_tx = ordering_test_tx!();
let mut tx = original_tx.clone();
(0..40)
.find(|_| {
TxOrdering::Shuffle.sort_tx(&mut tx);
original_tx.input != tx.input
})
.expect("it should have moved the inputs at least once");
let mut tx = original_tx.clone();
(0..40)
.find(|_| {
TxOrdering::Shuffle.sort_tx(&mut tx);
original_tx.output != tx.output
})
.expect("it should have moved the outputs at least once");
}
#[test]
fn test_output_ordering_custom_but_bip69() {
use core::str::FromStr;
let original_tx = ordering_test_tx!();
let mut tx = original_tx;
let bip69_txin_cmp = |tx_a: &TxIn, tx_b: &TxIn| {
let project_outpoint = |t: &TxIn| (t.previous_output.txid, t.previous_output.vout);
project_outpoint(tx_a).cmp(&project_outpoint(tx_b))
};
let bip69_txout_cmp = |tx_a: &TxOut, tx_b: &TxOut| {
let project_utxo = |t: &TxOut| (t.value, t.script_pubkey.clone());
project_utxo(tx_a).cmp(&project_utxo(tx_b))
};
let custom_bip69_ordering = TxOrdering::Custom {
input_sort: Arc::new(bip69_txin_cmp),
output_sort: Arc::new(bip69_txout_cmp),
};
custom_bip69_ordering.sort_tx(&mut tx);
assert_eq!(
tx.input[0].previous_output,
bitcoin::OutPoint::from_str(
"0e53ec5dfb2cb8a71fec32dc9a634a35b7e24799295ddd5278217822e0b31f57:5"
)
.unwrap()
);
assert_eq!(
tx.input[1].previous_output,
bitcoin::OutPoint::from_str(
"0f60fdd185542f2c6ea19030b0796051e7772b6026dd5ddccd7a2f93b73e6fc2:0"
)
.unwrap()
);
assert_eq!(
tx.input[2].previous_output,
bitcoin::OutPoint::from_str(
"0f60fdd185542f2c6ea19030b0796051e7772b6026dd5ddccd7a2f93b73e6fc2:1"
)
.unwrap()
);
assert_eq!(tx.output[0].value.to_sat(), 800);
assert_eq!(tx.output[1].script_pubkey, ScriptBuf::from(vec![0xAA]));
assert_eq!(
tx.output[2].script_pubkey,
ScriptBuf::from(vec![0xAA, 0xEE])
);
}
#[test]
fn test_output_ordering_custom_with_sha256() {
use bitcoin::hashes::{sha256, Hash};
let original_tx = ordering_test_tx!();
let mut tx_1 = original_tx.clone();
let mut tx_2 = original_tx.clone();
let shared_secret = "secret_tweak";
let hash_txin_with_shared_secret_seed = Arc::new(|tx_a: &TxIn, tx_b: &TxIn| {
let secret_digest_from_txin = |txin: &TxIn| {
sha256::Hash::hash(
&[
&txin.previous_output.txid.to_raw_hash()[..],
&txin.previous_output.vout.to_be_bytes(),
shared_secret.as_bytes(),
]
.concat(),
)
};
secret_digest_from_txin(tx_a).cmp(&secret_digest_from_txin(tx_b))
});
let hash_txout_with_shared_secret_seed = Arc::new(|tx_a: &TxOut, tx_b: &TxOut| {
let secret_digest_from_txout = |txin: &TxOut| {
sha256::Hash::hash(
&[
&txin.value.to_sat().to_be_bytes(),
&txin.script_pubkey.clone().into_bytes()[..],
shared_secret.as_bytes(),
]
.concat(),
)
};
secret_digest_from_txout(tx_a).cmp(&secret_digest_from_txout(tx_b))
});
let custom_ordering_from_salted_sha256_1 = TxOrdering::Custom {
input_sort: hash_txin_with_shared_secret_seed.clone(),
output_sort: hash_txout_with_shared_secret_seed.clone(),
};
let custom_ordering_from_salted_sha256_2 = TxOrdering::Custom {
input_sort: hash_txin_with_shared_secret_seed,
output_sort: hash_txout_with_shared_secret_seed,
};
custom_ordering_from_salted_sha256_1.sort_tx(&mut tx_1);
custom_ordering_from_salted_sha256_2.sort_tx(&mut tx_2);
// Check the ordering is consistent between calls
assert_eq!(tx_1, tx_2);
// Check transaction order has changed
assert_ne!(tx_1, original_tx);
assert_ne!(tx_2, original_tx);
}
fn get_test_utxos() -> Vec<LocalOutput> {
use bitcoin::hashes::Hash;
vec![
LocalOutput {
outpoint: OutPoint {
txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(),
vout: 0,
},
txout: TxOut::NULL,
keychain: KeychainKind::External,
is_spent: false,
confirmation_time: ConfirmationTime::Unconfirmed { last_seen: 0 },
derivation_index: 0,
},
LocalOutput {
outpoint: OutPoint {
txid: bitcoin::Txid::from_slice(&[0; 32]).unwrap(),
vout: 1,
},
txout: TxOut::NULL,
keychain: KeychainKind::Internal,
is_spent: false,
confirmation_time: ConfirmationTime::Confirmed {
height: 32,
time: 42,
},
derivation_index: 1,
},
]
}
#[test]
fn test_change_spend_policy_default() {
let change_spend_policy = ChangeSpendPolicy::default();
let filtered = get_test_utxos()
.into_iter()
.filter(|u| change_spend_policy.is_satisfied_by(u))
.count();
assert_eq!(filtered, 2);
}
#[test]
fn test_change_spend_policy_no_internal() {
let change_spend_policy = ChangeSpendPolicy::ChangeForbidden;
let filtered = get_test_utxos()
.into_iter()
.filter(|u| change_spend_policy.is_satisfied_by(u))
.collect::<Vec<_>>();
assert_eq!(filtered.len(), 1);
assert_eq!(filtered[0].keychain, KeychainKind::External);
}
#[test]
fn test_change_spend_policy_only_internal() {
let change_spend_policy = ChangeSpendPolicy::OnlyChange;
let filtered = get_test_utxos()
.into_iter()
.filter(|u| change_spend_policy.is_satisfied_by(u))
.collect::<Vec<_>>();
assert_eq!(filtered.len(), 1);
assert_eq!(filtered[0].keychain, KeychainKind::Internal);
}
#[test]
fn test_default_tx_version_1() {
let version = Version::default();
assert_eq!(version.0, 1);
}
}