From 59a8bd5d65f820c033617bb7dfe3b2903616f2d3 Mon Sep 17 00:00:00 2001 From: Duncan Dean Date: Fri, 12 Apr 2024 15:37:17 +0200 Subject: [PATCH] Add intermediate `ConstructedTransaction` --- lightning/src/ln/interactivetxs.rs | 281 ++++++++++++++++++++--------- 1 file changed, 194 insertions(+), 87 deletions(-) diff --git a/lightning/src/ln/interactivetxs.rs b/lightning/src/ln/interactivetxs.rs index 7d2fb1983..5f01bcd16 100644 --- a/lightning/src/ln/interactivetxs.rs +++ b/lightning/src/ln/interactivetxs.rs @@ -15,7 +15,8 @@ use bitcoin::blockdata::constants::WITNESS_SCALE_FACTOR; use bitcoin::consensus::Encodable; use bitcoin::policy::MAX_STANDARD_TX_WEIGHT; use bitcoin::{ - absolute::LockTime as AbsoluteLockTime, OutPoint, ScriptBuf, Sequence, Transaction, TxIn, TxOut, + absolute::LockTime as AbsoluteLockTime, OutPoint, ScriptBuf, Sequence, Transaction, TxIn, + TxOut, Weight, }; use crate::chain::chaininterface::fee_for_weight; @@ -77,7 +78,7 @@ impl SerialIdExt for SerialId { } #[derive(Debug, Clone, PartialEq)] -pub enum AbortReason { +pub(crate) enum AbortReason { InvalidStateTransition, UnexpectedCounterpartyMessage, ReceivedTooManyTxAddInputs, @@ -97,53 +98,183 @@ pub enum AbortReason { InvalidTx, } -#[derive(Debug)] -pub struct TxInputWithPrevOutput { +#[derive(Debug, Clone, PartialEq, Eq)] +pub(crate) struct InteractiveTxInput { + serial_id: SerialId, input: TxIn, prev_output: TxOut, } +#[derive(Debug, Clone, PartialEq, Eq)] +pub(crate) struct InteractiveTxOutput { + serial_id: SerialId, + tx_out: TxOut, +} + +#[derive(Debug, Clone, PartialEq, Eq)] +pub(crate) struct ConstructedTransaction { + holder_is_initiator: bool, + + inputs: Vec, + outputs: Vec, + + local_inputs_value_satoshis: u64, + local_outputs_value_satoshis: u64, + + remote_inputs_value_satoshis: u64, + remote_outputs_value_satoshis: u64, + + lock_time: AbsoluteLockTime, +} + +impl ConstructedTransaction { + fn new(context: NegotiationContext) -> Self { + let local_inputs_value_satoshis = context + .inputs + .iter() + .filter(|(serial_id, _)| { + !is_serial_id_valid_for_counterparty(context.holder_is_initiator, serial_id) + }) + .fold(0u64, |value, (_, input)| value.saturating_add(input.prev_output.value)); + + let local_outputs_value_satoshis = context + .outputs + .iter() + .filter(|(serial_id, _)| { + !is_serial_id_valid_for_counterparty(context.holder_is_initiator, serial_id) + }) + .fold(0u64, |value, (_, output)| value.saturating_add(output.tx_out.value)); + + Self { + holder_is_initiator: context.holder_is_initiator, + + local_inputs_value_satoshis, + local_outputs_value_satoshis, + + remote_inputs_value_satoshis: context.remote_inputs_value(), + remote_outputs_value_satoshis: context.remote_outputs_value(), + + inputs: context.inputs.into_values().collect(), + outputs: context.outputs.into_values().collect(), + + lock_time: context.tx_locktime, + } + } + + pub fn weight(&self) -> Weight { + let inputs_weight = self.inputs.iter().fold( + Weight::from_wu(0), + |weight, InteractiveTxInput { prev_output, .. }| { + weight.checked_add(estimate_input_weight(prev_output)).unwrap_or(Weight::MAX) + }, + ); + let outputs_weight = self.outputs.iter().fold( + Weight::from_wu(0), + |weight, InteractiveTxOutput { tx_out, .. }| { + weight.checked_add(get_output_weight(&tx_out.script_pubkey)).unwrap_or(Weight::MAX) + }, + ); + Weight::from_wu(TX_COMMON_FIELDS_WEIGHT) + .checked_add(inputs_weight) + .and_then(|weight| weight.checked_add(outputs_weight)) + .unwrap_or(Weight::MAX) + } + + pub fn into_unsigned_tx(self) -> Transaction { + // Inputs and outputs must be sorted by serial_id + let ConstructedTransaction { mut inputs, mut outputs, .. } = self; + + inputs.sort_unstable_by_key(|InteractiveTxInput { serial_id, .. }| *serial_id); + outputs.sort_unstable_by_key(|InteractiveTxOutput { serial_id, .. }| *serial_id); + + let input: Vec = + inputs.into_iter().map(|InteractiveTxInput { input, .. }| input).collect(); + let output: Vec = + outputs.into_iter().map(|InteractiveTxOutput { tx_out, .. }| tx_out).collect(); + + Transaction { version: 2, lock_time: self.lock_time, input, output } + } +} + #[derive(Debug)] struct NegotiationContext { holder_is_initiator: bool, received_tx_add_input_count: u16, received_tx_add_output_count: u16, - inputs: HashMap, + inputs: HashMap, prevtx_outpoints: HashSet, - outputs: HashMap, + outputs: HashMap, tx_locktime: AbsoluteLockTime, feerate_sat_per_kw: u32, } -pub(crate) fn get_output_weight(script_pubkey: &ScriptBuf) -> u64 { - (8 /* value */ + script_pubkey.consensus_encode(&mut sink()).unwrap() as u64) - * WITNESS_SCALE_FACTOR as u64 +pub(crate) fn estimate_input_weight(prev_output: &TxOut) -> Weight { + Weight::from_wu(if prev_output.script_pubkey.is_v0_p2wpkh() { + P2WPKH_INPUT_WEIGHT_LOWER_BOUND + } else if prev_output.script_pubkey.is_v0_p2wsh() { + P2WSH_INPUT_WEIGHT_LOWER_BOUND + } else if prev_output.script_pubkey.is_v1_p2tr() { + P2TR_INPUT_WEIGHT_LOWER_BOUND + } else { + UNKNOWN_SEGWIT_VERSION_INPUT_WEIGHT_LOWER_BOUND + }) +} + +pub(crate) fn get_output_weight(script_pubkey: &ScriptBuf) -> Weight { + Weight::from_wu( + (8 /* value */ + script_pubkey.consensus_encode(&mut sink()).unwrap() as u64) + * WITNESS_SCALE_FACTOR as u64, + ) +} + +fn is_serial_id_valid_for_counterparty(holder_is_initiator: bool, serial_id: &SerialId) -> bool { + // A received `SerialId`'s parity must match the role of the counterparty. + holder_is_initiator == serial_id.is_for_non_initiator() } impl NegotiationContext { fn is_serial_id_valid_for_counterparty(&self, serial_id: &SerialId) -> bool { - // A received `SerialId`'s parity must match the role of the counterparty. - self.holder_is_initiator == serial_id.is_for_non_initiator() - } - - fn total_input_and_output_count(&self) -> usize { - self.inputs.len().saturating_add(self.outputs.len()) + is_serial_id_valid_for_counterparty(self.holder_is_initiator, serial_id) } - fn counterparty_inputs_contributed( - &self, - ) -> impl Iterator + Clone { + fn remote_inputs_value(&self) -> u64 { self.inputs .iter() - .filter(move |(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id)) - .map(|(_, input_with_prevout)| input_with_prevout) + .filter(|(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id)) + .fold(0u64, |acc, (_, InteractiveTxInput { prev_output, .. })| { + acc.saturating_add(prev_output.value) + }) } - fn counterparty_outputs_contributed(&self) -> impl Iterator + Clone { + fn remote_outputs_value(&self) -> u64 { self.outputs .iter() - .filter(move |(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id)) - .map(|(_, output)| output) + .filter(|(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id)) + .fold(0u64, |acc, (_, InteractiveTxOutput { tx_out, .. })| { + acc.saturating_add(tx_out.value) + }) + } + + fn remote_inputs_weight(&self) -> Weight { + Weight::from_wu( + self.inputs + .iter() + .filter(|(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id)) + .fold(0u64, |weight, (_, InteractiveTxInput { prev_output, .. })| { + weight.saturating_add(estimate_input_weight(prev_output).to_wu()) + }), + ) + } + + fn remote_outputs_weight(&self) -> Weight { + Weight::from_wu( + self.outputs + .iter() + .filter(|(serial_id, _)| self.is_serial_id_valid_for_counterparty(serial_id)) + .fold(0u64, |weight, (_, InteractiveTxOutput { tx_out, .. })| { + weight.saturating_add(get_output_weight(&tx_out.script_pubkey).to_wu()) + }), + ) } fn received_tx_add_input(&mut self, msg: &msgs::TxAddInput) -> Result<(), AbortReason> { @@ -213,7 +344,8 @@ impl NegotiationContext { }, hash_map::Entry::Vacant(entry) => { let prev_outpoint = OutPoint { txid, vout: msg.prevtx_out }; - entry.insert(TxInputWithPrevOutput { + entry.insert(InteractiveTxInput { + serial_id: msg.serial_id, input: TxIn { previous_output: prev_outpoint, sequence: Sequence(msg.sequence), @@ -269,7 +401,7 @@ impl NegotiationContext { // bitcoin supply. let mut outputs_value: u64 = 0; for output in self.outputs.iter() { - outputs_value = outputs_value.saturating_add(output.1.value); + outputs_value = outputs_value.saturating_add(output.1.tx_out.value); } if outputs_value.saturating_add(msg.sats) > TOTAL_BITCOIN_SUPPLY_SATOSHIS { // The receiving node: @@ -306,7 +438,10 @@ impl NegotiationContext { Err(AbortReason::DuplicateSerialId) }, hash_map::Entry::Vacant(entry) => { - entry.insert(TxOut { value: msg.sats, script_pubkey: msg.script.clone() }); + entry.insert(InteractiveTxOutput { + serial_id: msg.serial_id, + tx_out: TxOut { value: msg.sats, script_pubkey: msg.script.clone() }, + }); Ok(()) }, } @@ -340,13 +475,21 @@ impl NegotiationContext { // We have added an input that already exists return Err(AbortReason::PrevTxOutInvalid); } - self.inputs.insert(msg.serial_id, TxInputWithPrevOutput { input, prev_output }); + self.inputs.insert( + msg.serial_id, + InteractiveTxInput { serial_id: msg.serial_id, input, prev_output }, + ); Ok(()) } fn sent_tx_add_output(&mut self, msg: &msgs::TxAddOutput) -> Result<(), AbortReason> { - self.outputs - .insert(msg.serial_id, TxOut { value: msg.sats, script_pubkey: msg.script.clone() }); + self.outputs.insert( + msg.serial_id, + InteractiveTxOutput { + serial_id: msg.serial_id, + tx_out: TxOut { value: msg.sats, script_pubkey: msg.script.clone() }, + }, + ); Ok(()) } @@ -361,31 +504,12 @@ impl NegotiationContext { } fn check_counterparty_fees( - &self, counterparty_inputs_value: u64, counterparty_outputs_value: u64, + &self, counterparty_fees_contributed: u64, ) -> Result<(), AbortReason> { - let mut counterparty_weight_contributed: u64 = self - .counterparty_outputs_contributed() - .map(|output| get_output_weight(&output.script_pubkey)) - .sum(); - // We don't know the counterparty's witnesses ahead of time obviously, so we use the lower bounds - // specified in BOLT 3. - let mut total_inputs_weight: u64 = 0; - for TxInputWithPrevOutput { prev_output, .. } in self.counterparty_inputs_contributed() { - total_inputs_weight = - total_inputs_weight.saturating_add(if prev_output.script_pubkey.is_v0_p2wpkh() { - P2WPKH_INPUT_WEIGHT_LOWER_BOUND - } else if prev_output.script_pubkey.is_v0_p2wsh() { - P2WSH_INPUT_WEIGHT_LOWER_BOUND - } else if prev_output.script_pubkey.is_v1_p2tr() { - P2TR_INPUT_WEIGHT_LOWER_BOUND - } else { - UNKNOWN_SEGWIT_VERSION_INPUT_WEIGHT_LOWER_BOUND - }); - } - counterparty_weight_contributed = - counterparty_weight_contributed.saturating_add(total_inputs_weight); - let counterparty_fees_contributed = - counterparty_inputs_value.saturating_sub(counterparty_outputs_value); + let counterparty_weight_contributed = self + .remote_inputs_weight() + .to_wu() + .saturating_add(self.remote_outputs_weight().to_wu()); let mut required_counterparty_contribution_fee = fee_for_weight(self.feerate_sat_per_kw, counterparty_weight_contributed); if !self.holder_is_initiator { @@ -402,21 +526,14 @@ impl NegotiationContext { Ok(()) } - fn build_transaction(self) -> Result { + fn validate_tx(self) -> Result { // The receiving node: // MUST fail the negotiation if: // - the peer's total input satoshis is less than their outputs - let mut counterparty_inputs_value: u64 = 0; - let mut counterparty_outputs_value: u64 = 0; - for input in self.counterparty_inputs_contributed() { - counterparty_inputs_value = - counterparty_inputs_value.saturating_add(input.prev_output.value); - } - for output in self.counterparty_outputs_contributed() { - counterparty_outputs_value = counterparty_outputs_value.saturating_add(output.value); - } - if counterparty_inputs_value < counterparty_outputs_value { + let remote_inputs_value = self.remote_inputs_value(); + let remote_outputs_value = self.remote_outputs_value(); + if remote_inputs_value < remote_outputs_value { return Err(AbortReason::OutputsValueExceedsInputsValue); } @@ -429,25 +546,15 @@ impl NegotiationContext { } // - the peer's paid feerate does not meet or exceed the agreed feerate (based on the minimum fee). - self.check_counterparty_fees(counterparty_inputs_value, counterparty_outputs_value)?; + self.check_counterparty_fees(remote_inputs_value.saturating_sub(remote_outputs_value))?; - // Inputs and outputs must be sorted by serial_id - let mut inputs = self.inputs.into_iter().collect::>(); - let mut outputs = self.outputs.into_iter().collect::>(); - inputs.sort_unstable_by_key(|(serial_id, _)| *serial_id); - outputs.sort_unstable_by_key(|(serial_id, _)| *serial_id); + let constructed_tx = ConstructedTransaction::new(self); - let tx_to_validate = Transaction { - version: 2, - lock_time: self.tx_locktime, - input: inputs.into_iter().map(|(_, input)| input.input).collect(), - output: outputs.into_iter().map(|(_, output)| output).collect(), - }; - if tx_to_validate.weight().to_wu() > MAX_STANDARD_TX_WEIGHT as u64 { + if constructed_tx.weight().to_wu() > MAX_STANDARD_TX_WEIGHT as u64 { return Err(AbortReason::TransactionTooLarge); } - Ok(tx_to_validate) + Ok(constructed_tx) } } @@ -535,7 +642,7 @@ define_state!( ReceivedTxComplete, "We have received a `tx_complete` message and the counterparty is awaiting ours." ); -define_state!(NegotiationComplete, Transaction, "We have exchanged consecutive `tx_complete` messages with the counterparty and the transaction negotiation is complete."); +define_state!(NegotiationComplete, ConstructedTransaction, "We have exchanged consecutive `tx_complete` messages with the counterparty and the transaction negotiation is complete."); define_state!( NegotiationAborted, AbortReason, @@ -577,7 +684,7 @@ macro_rules! define_state_transitions { impl StateTransition for $tx_complete_state { fn transition(self, _data: &msgs::TxComplete) -> StateTransitionResult { let context = self.into_negotiation_context(); - let tx = context.build_transaction()?; + let tx = context.validate_tx()?; Ok(NegotiationComplete(tx)) } } @@ -715,14 +822,14 @@ impl StateMachine { ]); } -pub struct InteractiveTxConstructor { +pub(crate) struct InteractiveTxConstructor { state_machine: StateMachine, channel_id: ChannelId, inputs_to_contribute: Vec<(SerialId, TxIn, TransactionU16LenLimited)>, outputs_to_contribute: Vec<(SerialId, TxOut)>, } -pub enum InteractiveTxMessageSend { +pub(crate) enum InteractiveTxMessageSend { TxAddInput(msgs::TxAddInput), TxAddOutput(msgs::TxAddOutput), TxComplete(msgs::TxComplete), @@ -754,10 +861,10 @@ where serial_id } -pub enum HandleTxCompleteValue { +pub(crate) enum HandleTxCompleteValue { SendTxMessage(InteractiveTxMessageSend), - SendTxComplete(InteractiveTxMessageSend, Transaction), - NegotiationComplete(Transaction), + SendTxComplete(InteractiveTxMessageSend, ConstructedTransaction), + NegotiationComplete(ConstructedTransaction), } impl InteractiveTxConstructor { @@ -1107,7 +1214,7 @@ mod tests { } assert!(message_send_a.is_none()); assert!(message_send_b.is_none()); - assert_eq!(final_tx_a, final_tx_b); + assert_eq!(final_tx_a.unwrap().into_unsigned_tx(), final_tx_b.unwrap().into_unsigned_tx()); assert!(session.expect_error.is_none(), "Test: {}", session.description); } @@ -1280,7 +1387,7 @@ mod tests { let p2wpkh_fee = fee_for_weight(TEST_FEERATE_SATS_PER_KW, P2WPKH_INPUT_WEIGHT_LOWER_BOUND); let outputs_fee = fee_for_weight( TEST_FEERATE_SATS_PER_KW, - get_output_weight(&generate_p2wpkh_script_pubkey()), + get_output_weight(&generate_p2wpkh_script_pubkey()).to_wu(), ); let tx_common_fields_fee = fee_for_weight(TEST_FEERATE_SATS_PER_KW, TX_COMMON_FIELDS_WEIGHT); -- 2.39.5