// You may not use this file except in accordance with one or both of these
// licenses.
-use bitcoin::blockdata::transaction::TxOut;
+use bitcoin::amount::Amount;
+use bitcoin::blockdata::transaction::{Transaction, TxOut};
+use bitcoin::blockdata::script::ScriptBuf;
+use bitcoin::consensus::Encodable;
+use bitcoin::consensus::encode::VarInt;
-use std::cmp::Ordering;
+#[allow(unused_imports)]
+use crate::prelude::*;
+
+use crate::io_extras::sink;
+use core::cmp::Ordering;
pub fn sort_outputs<T, C : Fn(&T, &T) -> Ordering>(outputs: &mut Vec<(TxOut, T)>, tie_breaker: C) {
outputs.sort_unstable_by(|a, b| {
});
}
+/// Possibly adds a change output to the given transaction, always doing so if there are excess
+/// funds available beyond the requested feerate.
+/// Assumes at least one input will have a witness (ie spends a segwit output).
+/// Returns an Err(()) if the requested feerate cannot be met.
+/// Returns the expected maximum weight of the fully signed transaction on success.
+pub(crate) fn maybe_add_change_output(tx: &mut Transaction, input_value: Amount, witness_max_weight: u64, feerate_sat_per_1000_weight: u32, change_destination_script: ScriptBuf) -> Result<u64, ()> {
+ if input_value > Amount::MAX_MONEY { return Err(()); }
+
+ const WITNESS_FLAG_BYTES: u64 = 2;
+
+ let mut output_value = Amount::ZERO;
+ for output in tx.output.iter() {
+ output_value += output.value;
+ if output_value >= input_value { return Err(()); }
+ }
+
+ let dust_value = change_destination_script.dust_value();
+ let mut change_output = TxOut {
+ script_pubkey: change_destination_script,
+ value: Amount::ZERO,
+ };
+ let change_len = change_output.consensus_encode(&mut sink()).unwrap();
+ let starting_weight = tx.weight().to_wu() + WITNESS_FLAG_BYTES + witness_max_weight as u64;
+ let mut weight_with_change: i64 = starting_weight as i64 + change_len as i64 * 4;
+ // Include any extra bytes required to push an extra output.
+ weight_with_change += (VarInt(tx.output.len() as u64 + 1).size() - VarInt(tx.output.len() as u64).size()) as i64 * 4;
+ // When calculating weight, add two for the flag bytes
+ let change_value: i64 = (input_value - output_value).to_sat() as i64 - weight_with_change * feerate_sat_per_1000_weight as i64 / 1000;
+ if change_value >= dust_value.to_sat() as i64 {
+ change_output.value = Amount::from_sat(change_value as u64);
+ tx.output.push(change_output);
+ Ok(weight_with_change as u64)
+ } else if (input_value - output_value).to_sat() as i64 - (starting_weight as i64) * feerate_sat_per_1000_weight as i64 / 1000 < 0 {
+ Err(())
+ } else {
+ Ok(starting_weight)
+ }
+}
+
#[cfg(test)]
mod tests {
use super::*;
- use bitcoin::blockdata::script::{Script, Builder};
- use bitcoin::blockdata::transaction::TxOut;
+ use bitcoin::amount::Amount;
+ use bitcoin::blockdata::locktime::absolute::LockTime;
+ use bitcoin::blockdata::transaction::{TxIn, OutPoint, Version};
+ use bitcoin::blockdata::script::Builder;
+ use bitcoin::hash_types::Txid;
+ use bitcoin::hashes::Hash;
+ use bitcoin::hashes::hex::FromHex;
+ use bitcoin::{PubkeyHash, Sequence, Witness};
- use hex::decode;
+ use alloc::vec;
#[test]
fn sort_output_by_value() {
let txout1 = TxOut {
- value: 100,
+ value: Amount::from_sat(100),
script_pubkey: Builder::new().push_int(0).into_script()
};
let txout1_ = txout1.clone();
let txout2 = TxOut {
- value: 99,
+ value: Amount::from_sat(99),
script_pubkey: Builder::new().push_int(0).into_script()
};
let txout2_ = txout2.clone();
#[test]
fn sort_output_by_script_pubkey() {
let txout1 = TxOut {
- value: 100,
+ value: Amount::from_sat(100),
script_pubkey: Builder::new().push_int(3).into_script(),
};
let txout1_ = txout1.clone();
let txout2 = TxOut {
- value: 100,
+ value: Amount::from_sat(100),
script_pubkey: Builder::new().push_int(1).push_int(2).into_script()
};
let txout2_ = txout2.clone();
#[test]
fn sort_output_by_bip_test() {
let txout1 = TxOut {
- value: 100000000,
+ value: Amount::from_sat(100000000),
script_pubkey: script_from_hex("41046a0765b5865641ce08dd39690aade26dfbf5511430ca428a3089261361cef170e3929a68aee3d8d4848b0c5111b0a37b82b86ad559fd2a745b44d8e8d9dfdc0cac")
};
let txout1_ = txout1.clone();
// doesn't deserialize cleanly:
let txout2 = TxOut {
- value: 2400000000,
+ value: Amount::from_sat(2400000000),
script_pubkey: script_from_hex("41044a656f065871a353f216ca26cef8dde2f03e8c16202d2e8ad769f02032cb86a5eb5e56842e92e19141d60a01928f8dd2c875a390f67c1f6c94cfc617c0ea45afac")
};
let txout2_ = txout2.clone();
#[test]
fn sort_output_tie_breaker_test() {
let txout1 = TxOut {
- value: 100,
+ value: Amount::from_sat(100),
script_pubkey: Builder::new().push_int(1).push_int(2).into_script()
};
let txout1_ = txout1.clone();
);
}
- fn script_from_hex(hex_str: &str) -> Script {
- Script::from(decode(hex_str).unwrap())
+ fn script_from_hex(hex_str: &str) -> ScriptBuf {
+ ScriptBuf::from(<Vec<u8>>::from_hex(hex_str).unwrap())
}
macro_rules! bip_txout_tests {
let expected_raw: Vec<(u64, &str)> = $value;
let expected: Vec<(TxOut, &str)> = expected_raw.iter()
.map(|txout_raw| TxOut {
- value: txout_raw.0,
+ value: Amount::from_sat(txout_raw.0),
script_pubkey: script_from_hex(txout_raw.1)
}).map(|txout| (txout, "ignore"))
.collect();
bip69_txout_test_1: TXOUT1.to_vec(),
bip69_txout_test_2: TXOUT2.to_vec(),
}
+
+ #[test]
+ fn test_tx_value_overrun() {
+ // If we have a bogus input amount or outputs valued more than inputs, we should fail
+ let mut tx = Transaction { version: Version::TWO, lock_time: LockTime::ZERO, input: Vec::new(), output: vec![TxOut {
+ script_pubkey: ScriptBuf::new(), value: Amount::from_sat(1000)
+ }] };
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(21_000_000_0000_0001), 0, 253, ScriptBuf::new()).is_err());
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(400), 0, 253, ScriptBuf::new()).is_err());
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(4000), 0, 253, ScriptBuf::new()).is_ok());
+ }
+
+ #[test]
+ fn test_tx_change_edge() {
+ // Check that we never add dust outputs
+ let mut tx = Transaction { version: Version::TWO, lock_time: LockTime::ZERO, input: Vec::new(), output: Vec::new() };
+ let orig_wtxid = tx.wtxid();
+ let output_spk = ScriptBuf::new_p2pkh(&PubkeyHash::hash(&[0; 0]));
+ assert_eq!(output_spk.dust_value().to_sat(), 546);
+ // base size = version size + varint[input count] + input size + varint[output count] + output size + lock time size
+ // total size = version size + marker + flag + varint[input count] + input size + varint[output count] + output size + lock time size
+ // weight = 3 * base size + total size = 3 * (4 + 1 + 0 + 1 + 0 + 4) + (4 + 1 + 1 + 1 + 0 + 1 + 0 + 4) = 3 * 10 + 12 = 42
+ assert_eq!(tx.weight().to_wu(), 42);
+ // 10 sats isn't enough to pay fee on a dummy transaction...
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(10), 0, 250, output_spk.clone()).is_err());
+ assert_eq!(tx.wtxid(), orig_wtxid); // Failure doesn't change the transaction
+ // but 11 (= ceil(42 * 250 / 1000)) is, just not enough to add a change output...
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(11), 0, 250, output_spk.clone()).is_ok());
+ assert_eq!(tx.output.len(), 0);
+ assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(549), 0, 250, output_spk.clone()).is_ok());
+ assert_eq!(tx.output.len(), 0);
+ assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
+ // 590 is also not enough
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(590), 0, 250, output_spk.clone()).is_ok());
+ assert_eq!(tx.output.len(), 0);
+ assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
+ // at 591 we can afford the change output at the dust limit (546)
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(591), 0, 250, output_spk.clone()).is_ok());
+ assert_eq!(tx.output.len(), 1);
+ assert_eq!(tx.output[0].value.to_sat(), 546);
+ assert_eq!(tx.output[0].script_pubkey, output_spk);
+ assert_eq!(tx.weight().to_wu() / 4, 590-546); // New weight is exactly the fee we wanted.
+
+ tx.output.pop();
+ assert_eq!(tx.wtxid(), orig_wtxid); // The only change is the addition of one output.
+ }
+
+ #[test]
+ fn test_tx_extra_outputs() {
+ // Check that we correctly handle existing outputs
+ let mut tx = Transaction { version: Version::TWO, lock_time: LockTime::ZERO, input: vec![TxIn {
+ previous_output: OutPoint::new(Txid::all_zeros(), 0), script_sig: ScriptBuf::new(), witness: Witness::new(), sequence: Sequence::ZERO,
+ }], output: vec![TxOut {
+ script_pubkey: Builder::new().push_int(1).into_script(), value: Amount::from_sat(1000)
+ }] };
+ let orig_wtxid = tx.wtxid();
+ let orig_weight = tx.weight().to_wu();
+ assert_eq!(orig_weight / 4, 61);
+
+ assert_eq!(Builder::new().push_int(2).into_script().dust_value().to_sat(), 474);
+
+ // Input value of the output value + fee - 1 should fail:
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(1000 + 61 + 100 - 1), 400, 250, Builder::new().push_int(2).into_script()).is_err());
+ assert_eq!(tx.wtxid(), orig_wtxid); // Failure doesn't change the transaction
+ // but one more input sat should succeed, without changing the transaction
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(1000 + 61 + 100), 400, 250, Builder::new().push_int(2).into_script()).is_ok());
+ assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
+ // In order to get a change output, we need to add 474 plus the output's weight / 4 (10)...
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(1000 + 61 + 100 + 474 + 9), 400, 250, Builder::new().push_int(2).into_script()).is_ok());
+ assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
+
+ assert!(maybe_add_change_output(&mut tx, Amount::from_sat(1000 + 61 + 100 + 474 + 10), 400, 250, Builder::new().push_int(2).into_script()).is_ok());
+ assert_eq!(tx.output.len(), 2);
+ assert_eq!(tx.output[1].value.to_sat(), 474);
+ assert_eq!(tx.output[1].script_pubkey, Builder::new().push_int(2).into_script());
+ assert_eq!(tx.weight().to_wu() - orig_weight, 40); // Weight difference matches what we had to add above
+ tx.output.pop();
+ assert_eq!(tx.wtxid(), orig_wtxid); // The only change is the addition of one output.
+ }
}