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::blockdata::transaction::{Transaction, TxOut};
11 use bitcoin::blockdata::script::Script;
12 use bitcoin::consensus::Encodable;
13 use bitcoin::consensus::encode::VarInt;
15 use ln::msgs::MAX_VALUE_MSAT;
18 use core::cmp::Ordering;
20 pub fn sort_outputs<T, C : Fn(&T, &T) -> Ordering>(outputs: &mut Vec<(TxOut, T)>, tie_breaker: C) {
21 outputs.sort_unstable_by(|a, b| {
22 a.0.value.cmp(&b.0.value).then_with(|| {
23 a.0.script_pubkey[..].cmp(&b.0.script_pubkey[..]).then_with(|| {
24 tie_breaker(&a.1, &b.1)
30 fn get_dust_value(output_script: &Script) -> u64 {
31 //TODO: This belongs in rust-bitcoin (https://github.com/rust-bitcoin/rust-bitcoin/pull/566)
32 if output_script.is_op_return() {
34 } else if output_script.is_witness_program() {
41 /// Possibly adds a change output to the given transaction, always doing so if there are excess
42 /// funds available beyond the requested feerate.
43 /// Assumes at least one input will have a witness (ie spends a segwit output).
44 /// Returns an Err(()) if the requested feerate cannot be met.
45 pub(crate) fn maybe_add_change_output(tx: &mut Transaction, input_value: u64, witness_max_weight: usize, feerate_sat_per_1000_weight: u32, change_destination_script: Script) -> Result<(), ()> {
46 if input_value > MAX_VALUE_MSAT / 1000 { return Err(()); }
48 let mut output_value = 0;
49 for output in tx.output.iter() {
50 output_value += output.value;
51 if output_value >= input_value { return Err(()); }
54 let dust_value = get_dust_value(&change_destination_script);
55 let mut change_output = TxOut {
56 script_pubkey: change_destination_script,
59 let change_len = change_output.consensus_encode(&mut std::io::sink()).unwrap();
60 let mut weight_with_change: i64 = tx.get_weight() as i64 + 2 + witness_max_weight as i64 + change_len as i64 * 4;
61 // Include any extra bytes required to push an extra output.
62 weight_with_change += (VarInt(tx.output.len() as u64 + 1).len() - VarInt(tx.output.len() as u64).len()) as i64 * 4;
63 // When calculating weight, add two for the flag bytes
64 let change_value: i64 = (input_value - output_value) as i64 - weight_with_change * feerate_sat_per_1000_weight as i64 / 1000;
65 if change_value >= dust_value as i64 {
66 change_output.value = change_value as u64;
67 tx.output.push(change_output);
68 } else if (input_value - output_value) as i64 - (tx.get_weight() as i64 + 2 + witness_max_weight as i64) * feerate_sat_per_1000_weight as i64 / 1000 < 0 {
79 use bitcoin::blockdata::transaction::{Transaction, TxOut, TxIn, OutPoint};
80 use bitcoin::blockdata::script::{Script, Builder};
81 use bitcoin::hash_types::Txid;
83 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
90 fn sort_output_by_value() {
93 script_pubkey: Builder::new().push_int(0).into_script()
95 let txout1_ = txout1.clone();
99 script_pubkey: Builder::new().push_int(0).into_script()
101 let txout2_ = txout2.clone();
103 let mut outputs = vec![(txout1, "ignore"), (txout2, "ignore")];
104 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
108 &vec![(txout2_, "ignore"), (txout1_, "ignore")]
113 fn sort_output_by_script_pubkey() {
116 script_pubkey: Builder::new().push_int(3).into_script(),
118 let txout1_ = txout1.clone();
122 script_pubkey: Builder::new().push_int(1).push_int(2).into_script()
124 let txout2_ = txout2.clone();
126 let mut outputs = vec![(txout1, "ignore"), (txout2, "ignore")];
127 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
131 &vec![(txout2_, "ignore"), (txout1_, "ignore")]
136 fn sort_output_by_bip_test() {
139 script_pubkey: script_from_hex("41046a0765b5865641ce08dd39690aade26dfbf5511430ca428a3089261361cef170e3929a68aee3d8d4848b0c5111b0a37b82b86ad559fd2a745b44d8e8d9dfdc0cac")
141 let txout1_ = txout1.clone();
143 // doesn't deserialize cleanly:
146 script_pubkey: script_from_hex("41044a656f065871a353f216ca26cef8dde2f03e8c16202d2e8ad769f02032cb86a5eb5e56842e92e19141d60a01928f8dd2c875a390f67c1f6c94cfc617c0ea45afac")
148 let txout2_ = txout2.clone();
150 let mut outputs = vec![(txout1, "ignore"), (txout2, "ignore")];
151 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
153 assert_eq!(&outputs, &vec![(txout1_, "ignore"), (txout2_, "ignore")]);
157 fn sort_output_tie_breaker_test() {
160 script_pubkey: Builder::new().push_int(1).push_int(2).into_script()
162 let txout1_ = txout1.clone();
164 let txout2 = txout1.clone();
165 let txout2_ = txout1.clone();
167 let mut outputs = vec![(txout1, 420), (txout2, 69)];
168 sort_outputs(&mut outputs, |a, b| { a.cmp(b) });
172 &vec![(txout2_, 69), (txout1_, 420)]
176 fn script_from_hex(hex_str: &str) -> Script {
177 Script::from(decode(hex_str).unwrap())
180 macro_rules! bip_txout_tests {
181 ($($name:ident: $value:expr,)*) => {
185 let expected_raw: Vec<(u64, &str)> = $value;
186 let expected: Vec<(TxOut, &str)> = expected_raw.iter()
187 .map(|txout_raw| TxOut {
189 script_pubkey: script_from_hex(txout_raw.1)
190 }).map(|txout| (txout, "ignore"))
193 let mut outputs = expected.clone();
194 outputs.reverse(); // prep it
196 // actually do the work!
197 sort_outputs(&mut outputs, |_, _| { unreachable!(); });
199 assert_eq!(outputs, expected);
205 const TXOUT1: [(u64, &str); 2] = [
206 (400057456, "76a9144a5fba237213a062f6f57978f796390bdcf8d01588ac"),
207 (40000000000, "76a9145be32612930b8323add2212a4ec03c1562084f8488ac"),
209 const TXOUT2: [(u64, &str); 2] = [
210 (100000000, "41046a0765b5865641ce08dd39690aade26dfbf5511430ca428a3089261361cef170e3929a68aee3d8d4848b0c5111b0a37b82b86ad559fd2a745b44d8e8d9dfdc0cac"),
211 (2400000000, "41044a656f065871a353f216ca26cef8dde2f03e8c16202d2e8ad769f02032cb86a5eb5e56842e92e19141d60a01928f8dd2c875a390f67c1f6c94cfc617c0ea45afac"),
214 bip69_txout_test_1: TXOUT1.to_vec(),
215 bip69_txout_test_2: TXOUT2.to_vec(),
219 fn test_tx_value_overrun() {
220 // If we have a bogus input amount or outputs valued more than inputs, we should fail
221 let mut tx = Transaction { version: 2, lock_time: 0, input: Vec::new(), output: vec![TxOut {
222 script_pubkey: Script::new(), value: 1000
224 assert!(maybe_add_change_output(&mut tx, 21_000_000_0000_0001, 0, 253, Script::new()).is_err());
225 assert!(maybe_add_change_output(&mut tx, 400, 0, 253, Script::new()).is_err());
226 assert!(maybe_add_change_output(&mut tx, 4000, 0, 253, Script::new()).is_ok());
230 fn test_tx_change_edge() {
231 // Check that we never add dust outputs
232 let mut tx = Transaction { version: 2, lock_time: 0, input: Vec::new(), output: Vec::new() };
233 let orig_wtxid = tx.wtxid();
234 // 9 sats isn't enough to pay fee on a dummy transaction...
235 assert_eq!(tx.get_weight() as u64, 40); // ie 10 vbytes
236 assert!(maybe_add_change_output(&mut tx, 9, 0, 253, Script::new()).is_err());
237 assert_eq!(tx.wtxid(), orig_wtxid); // Failure doesn't change the transaction
238 // but 10-564 is, just not enough to add a change output...
239 assert!(maybe_add_change_output(&mut tx, 10, 0, 253, Script::new()).is_ok());
240 assert_eq!(tx.output.len(), 0);
241 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
242 assert!(maybe_add_change_output(&mut tx, 564, 0, 253, Script::new()).is_ok());
243 assert_eq!(tx.output.len(), 0);
244 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
245 // 565 is also not enough, if we anticipate 2 more weight units pushing us up to the next vbyte
246 // (considering the two bytes for segwit flags)
247 assert!(maybe_add_change_output(&mut tx, 565, 2, 253, Script::new()).is_ok());
248 assert_eq!(tx.output.len(), 0);
249 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
250 // at 565 we can afford the change output at the dust limit (546)
251 assert!(maybe_add_change_output(&mut tx, 565, 0, 253, Script::new()).is_ok());
252 assert_eq!(tx.output.len(), 1);
253 assert_eq!(tx.output[0].value, 546);
254 assert_eq!(tx.output[0].script_pubkey, Script::new());
255 assert_eq!(tx.get_weight() / 4, 565-546); // New weight is exactly the fee we wanted.
258 assert_eq!(tx.wtxid(), orig_wtxid); // The only change is the addition of one output.
262 fn test_tx_extra_outputs() {
263 // Check that we correctly handle existing outputs
264 let mut tx = Transaction { version: 2, lock_time: 0, input: vec![TxIn {
265 previous_output: OutPoint::new(Txid::from_hash(Sha256dHash::default()), 0), script_sig: Script::new(), witness: Vec::new(), sequence: 0,
266 }], output: vec![TxOut {
267 script_pubkey: Builder::new().push_int(1).into_script(), value: 1000
269 let orig_wtxid = tx.wtxid();
270 let orig_weight = tx.get_weight();
271 assert_eq!(orig_weight / 4, 61);
273 // Input value of the output value + fee - 1 should fail:
274 assert!(maybe_add_change_output(&mut tx, 1000 + 61 + 100 - 1, 400, 250, Builder::new().push_int(2).into_script()).is_err());
275 assert_eq!(tx.wtxid(), orig_wtxid); // Failure doesn't change the transaction
276 // but one more input sat should succeed, without changing the transaction
277 assert!(maybe_add_change_output(&mut tx, 1000 + 61 + 100, 400, 250, Builder::new().push_int(2).into_script()).is_ok());
278 assert_eq!(tx.wtxid(), orig_wtxid); // If we don't add an output, we don't change the transaction
279 // In order to get a change output, we need to add 546 plus the output's weight / 4 (10)...
280 assert!(maybe_add_change_output(&mut tx, 1000 + 61 + 100 + 546 + 9, 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
283 assert!(maybe_add_change_output(&mut tx, 1000 + 61 + 100 + 546 + 10, 400, 250, Builder::new().push_int(2).into_script()).is_ok());
284 assert_eq!(tx.output.len(), 2);
285 assert_eq!(tx.output[1].value, 546);
286 assert_eq!(tx.output[1].script_pubkey, Builder::new().push_int(2).into_script());
287 assert_eq!(tx.get_weight() - orig_weight, 40); // Weight difference matches what we had to add above
289 assert_eq!(tx.wtxid(), orig_wtxid); // The only change is the addition of one output.