1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 use bitcoin::amount::Amount;
11 use bitcoin::blockdata::transaction::{Transaction, TxOut};
12 use bitcoin::blockdata::script::ScriptBuf;
13 use bitcoin::consensus::Encodable;
14 use bitcoin::consensus::encode::VarInt;
16 #[allow(unused_imports)]
17 use crate::prelude::*;
19 use crate::io_extras::sink;
20 use core::cmp::Ordering;
22 pub fn sort_outputs<T, C : Fn(&T, &T) -> Ordering>(outputs: &mut Vec<(TxOut, T)>, tie_breaker: C) {
23 outputs.sort_unstable_by(|a, b| {
24 a.0.value.cmp(&b.0.value).then_with(|| {
25 a.0.script_pubkey[..].cmp(&b.0.script_pubkey[..]).then_with(|| {
26 tie_breaker(&a.1, &b.1)
32 /// Possibly adds a change output to the given transaction, always doing so if there are excess
33 /// funds available beyond the requested feerate.
34 /// Assumes at least one input will have a witness (ie spends a segwit output).
35 /// Returns an Err(()) if the requested feerate cannot be met.
36 /// Returns the expected maximum weight of the fully signed transaction on success.
37 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, ()> {
38 if input_value > Amount::MAX_MONEY { return Err(()); }
40 const WITNESS_FLAG_BYTES: u64 = 2;
42 let mut output_value = Amount::ZERO;
43 for output in tx.output.iter() {
44 output_value += output.value;
45 if output_value >= input_value { return Err(()); }
48 let dust_value = change_destination_script.dust_value();
49 let mut change_output = TxOut {
50 script_pubkey: change_destination_script,
53 let change_len = change_output.consensus_encode(&mut sink()).unwrap();
54 let starting_weight = tx.weight().to_wu() + WITNESS_FLAG_BYTES + witness_max_weight as u64;
55 let mut weight_with_change: i64 = starting_weight as i64 + change_len as i64 * 4;
56 // Include any extra bytes required to push an extra output.
57 weight_with_change += (VarInt(tx.output.len() as u64 + 1).size() - VarInt(tx.output.len() as u64).size()) as i64 * 4;
58 // When calculating weight, add two for the flag bytes
59 let change_value: i64 = (input_value - output_value).to_sat() as i64 - weight_with_change * feerate_sat_per_1000_weight as i64 / 1000;
60 if change_value >= dust_value.to_sat() as i64 {
61 change_output.value = Amount::from_sat(change_value as u64);
62 tx.output.push(change_output);
63 Ok(weight_with_change as u64)
64 } else if (input_value - output_value).to_sat() as i64 - (starting_weight as i64) * feerate_sat_per_1000_weight as i64 / 1000 < 0 {
75 use bitcoin::amount::Amount;
76 use bitcoin::blockdata::locktime::absolute::LockTime;
77 use bitcoin::blockdata::transaction::{TxIn, OutPoint, Version};
78 use bitcoin::blockdata::script::Builder;
79 use bitcoin::hash_types::Txid;
80 use bitcoin::hashes::Hash;
81 use bitcoin::hashes::hex::FromHex;
82 use bitcoin::{PubkeyHash, Sequence, Witness};
87 fn sort_output_by_value() {
89 value: Amount::from_sat(100),
90 script_pubkey: Builder::new().push_int(0).into_script()
92 let txout1_ = txout1.clone();
95 value: Amount::from_sat(99),
96 script_pubkey: Builder::new().push_int(0).into_script()
98 let txout2_ = txout2.clone();
100 let mut outputs = vec![(txout1, "ignore"), (txout2, "ignore")];
101 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
105 &vec![(txout2_, "ignore"), (txout1_, "ignore")]
110 fn sort_output_by_script_pubkey() {
112 value: Amount::from_sat(100),
113 script_pubkey: Builder::new().push_int(3).into_script(),
115 let txout1_ = txout1.clone();
118 value: Amount::from_sat(100),
119 script_pubkey: Builder::new().push_int(1).push_int(2).into_script()
121 let txout2_ = txout2.clone();
123 let mut outputs = vec![(txout1, "ignore"), (txout2, "ignore")];
124 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
128 &vec![(txout2_, "ignore"), (txout1_, "ignore")]
133 fn sort_output_by_bip_test() {
135 value: Amount::from_sat(100000000),
136 script_pubkey: script_from_hex("41046a0765b5865641ce08dd39690aade26dfbf5511430ca428a3089261361cef170e3929a68aee3d8d4848b0c5111b0a37b82b86ad559fd2a745b44d8e8d9dfdc0cac")
138 let txout1_ = txout1.clone();
140 // doesn't deserialize cleanly:
142 value: Amount::from_sat(2400000000),
143 script_pubkey: script_from_hex("41044a656f065871a353f216ca26cef8dde2f03e8c16202d2e8ad769f02032cb86a5eb5e56842e92e19141d60a01928f8dd2c875a390f67c1f6c94cfc617c0ea45afac")
145 let txout2_ = txout2.clone();
147 let mut outputs = vec![(txout1, "ignore"), (txout2, "ignore")];
148 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
150 assert_eq!(&outputs, &vec![(txout1_, "ignore"), (txout2_, "ignore")]);
154 fn sort_output_tie_breaker_test() {
156 value: Amount::from_sat(100),
157 script_pubkey: Builder::new().push_int(1).push_int(2).into_script()
159 let txout1_ = txout1.clone();
161 let txout2 = txout1.clone();
162 let txout2_ = txout1.clone();
164 let mut outputs = vec![(txout1, 420), (txout2, 69)];
165 sort_outputs(&mut outputs, |a, b| { a.cmp(b) });
169 &vec![(txout2_, 69), (txout1_, 420)]
173 fn script_from_hex(hex_str: &str) -> ScriptBuf {
174 ScriptBuf::from(<Vec<u8>>::from_hex(hex_str).unwrap())
177 macro_rules! bip_txout_tests {
178 ($($name:ident: $value:expr,)*) => {
182 let expected_raw: Vec<(u64, &str)> = $value;
183 let expected: Vec<(TxOut, &str)> = expected_raw.iter()
184 .map(|txout_raw| TxOut {
185 value: Amount::from_sat(txout_raw.0),
186 script_pubkey: script_from_hex(txout_raw.1)
187 }).map(|txout| (txout, "ignore"))
190 let mut outputs = expected.clone();
191 outputs.reverse(); // prep it
193 // actually do the work!
194 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
196 assert_eq!(outputs, expected);
202 const TXOUT1: [(u64, &str); 2] = [
203 (400057456, "76a9144a5fba237213a062f6f57978f796390bdcf8d01588ac"),
204 (40000000000, "76a9145be32612930b8323add2212a4ec03c1562084f8488ac"),
206 const TXOUT2: [(u64, &str); 2] = [
207 (100000000, "41046a0765b5865641ce08dd39690aade26dfbf5511430ca428a3089261361cef170e3929a68aee3d8d4848b0c5111b0a37b82b86ad559fd2a745b44d8e8d9dfdc0cac"),
208 (2400000000, "41044a656f065871a353f216ca26cef8dde2f03e8c16202d2e8ad769f02032cb86a5eb5e56842e92e19141d60a01928f8dd2c875a390f67c1f6c94cfc617c0ea45afac"),
211 bip69_txout_test_1: TXOUT1.to_vec(),
212 bip69_txout_test_2: TXOUT2.to_vec(),
216 fn test_tx_value_overrun() {
217 // If we have a bogus input amount or outputs valued more than inputs, we should fail
218 let mut tx = Transaction { version: Version::TWO, lock_time: LockTime::ZERO, input: Vec::new(), output: vec![TxOut {
219 script_pubkey: ScriptBuf::new(), value: Amount::from_sat(1000)
221 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(21_000_000_0000_0001), 0, 253, ScriptBuf::new()).is_err());
222 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(400), 0, 253, ScriptBuf::new()).is_err());
223 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(4000), 0, 253, ScriptBuf::new()).is_ok());
227 fn test_tx_change_edge() {
228 // Check that we never add dust outputs
229 let mut tx = Transaction { version: Version::TWO, lock_time: LockTime::ZERO, input: Vec::new(), output: Vec::new() };
230 let orig_wtxid = tx.wtxid();
231 let output_spk = ScriptBuf::new_p2pkh(&PubkeyHash::hash(&[0; 0]));
232 assert_eq!(output_spk.dust_value().to_sat(), 546);
233 // base size = version size + varint[input count] + input size + varint[output count] + output size + lock time size
234 // total size = version size + marker + flag + varint[input count] + input size + varint[output count] + output size + lock time size
235 // 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
236 assert_eq!(tx.weight().to_wu(), 42);
237 // 10 sats isn't enough to pay fee on a dummy transaction...
238 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(10), 0, 250, output_spk.clone()).is_err());
239 assert_eq!(tx.wtxid(), orig_wtxid); // Failure doesn't change the transaction
240 // but 11 (= ceil(42 * 250 / 1000)) is, just not enough to add a change output...
241 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(11), 0, 250, output_spk.clone()).is_ok());
242 assert_eq!(tx.output.len(), 0);
243 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
244 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(549), 0, 250, output_spk.clone()).is_ok());
245 assert_eq!(tx.output.len(), 0);
246 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
247 // 590 is also not enough
248 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(590), 0, 250, output_spk.clone()).is_ok());
249 assert_eq!(tx.output.len(), 0);
250 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
251 // at 591 we can afford the change output at the dust limit (546)
252 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(591), 0, 250, output_spk.clone()).is_ok());
253 assert_eq!(tx.output.len(), 1);
254 assert_eq!(tx.output[0].value.to_sat(), 546);
255 assert_eq!(tx.output[0].script_pubkey, output_spk);
256 assert_eq!(tx.weight().to_wu() / 4, 590-546); // New weight is exactly the fee we wanted.
259 assert_eq!(tx.wtxid(), orig_wtxid); // The only change is the addition of one output.
263 fn test_tx_extra_outputs() {
264 // Check that we correctly handle existing outputs
265 let mut tx = Transaction { version: Version::TWO, lock_time: LockTime::ZERO, input: vec![TxIn {
266 previous_output: OutPoint::new(Txid::all_zeros(), 0), script_sig: ScriptBuf::new(), witness: Witness::new(), sequence: Sequence::ZERO,
267 }], output: vec![TxOut {
268 script_pubkey: Builder::new().push_int(1).into_script(), value: Amount::from_sat(1000)
270 let orig_wtxid = tx.wtxid();
271 let orig_weight = tx.weight().to_wu();
272 assert_eq!(orig_weight / 4, 61);
274 assert_eq!(Builder::new().push_int(2).into_script().dust_value().to_sat(), 474);
276 // Input value of the output value + fee - 1 should fail:
277 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());
278 assert_eq!(tx.wtxid(), orig_wtxid); // Failure doesn't change the transaction
279 // but one more input sat should succeed, without changing the transaction
280 assert!(maybe_add_change_output(&mut tx, Amount::from_sat(1000 + 61 + 100), 400, 250, Builder::new().push_int(2).into_script()).is_ok());
281 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
282 // In order to get a change output, we need to add 474 plus the output's weight / 4 (10)...
283 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());
284 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
286 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());
287 assert_eq!(tx.output.len(), 2);
288 assert_eq!(tx.output[1].value.to_sat(), 474);
289 assert_eq!(tx.output[1].script_pubkey, Builder::new().push_int(2).into_script());
290 assert_eq!(tx.weight().to_wu() - orig_weight, 40); // Weight difference matches what we had to add above
292 assert_eq!(tx.wtxid(), orig_wtxid); // The only change is the addition of one output.