From 3dd99ebda654f78e68307f14948cc2108934ad93 Mon Sep 17 00:00:00 2001 From: Devrandom Date: Tue, 31 Aug 2021 15:23:48 +0200 Subject: [PATCH] Factor out low-level build_closing_transaction --- lightning/src/ln/chan_utils.rs | 46 ++++++++++++++++++++++++- lightning/src/ln/channel.rs | 61 ++++++++++------------------------ 2 files changed, 62 insertions(+), 45 deletions(-) diff --git a/lightning/src/ln/chan_utils.rs b/lightning/src/ln/chan_utils.rs index 6bdef4307..492bf89c7 100644 --- a/lightning/src/ln/chan_utils.rs +++ b/lightning/src/ln/chan_utils.rs @@ -23,7 +23,7 @@ use bitcoin::hash_types::{Txid, PubkeyHash}; use ln::{PaymentHash, PaymentPreimage}; use ln::msgs::DecodeError; use util::ser::{Readable, Writeable, Writer}; -use util::byte_utils; +use util::{byte_utils, transaction_utils}; use bitcoin::hash_types::WPubkeyHash; use bitcoin::secp256k1::key::{SecretKey, PublicKey}; @@ -80,6 +80,50 @@ pub fn build_commitment_secret(commitment_seed: &[u8; 32], idx: u64) -> [u8; 32] res } +/// Build a closing transaction +pub fn build_closing_transaction(value_to_holder: u64, value_to_counterparty: u64, holder_shutdown_script: Script, counterparty_shutdown_script: Script, funding_outpoint: OutPoint) -> Transaction { + let txins = { + let mut ins: Vec = Vec::new(); + ins.push(TxIn { + previous_output: funding_outpoint, + script_sig: Script::new(), + sequence: 0xffffffff, + witness: Vec::new(), + }); + ins + }; + + let mut txouts: Vec<(TxOut, ())> = Vec::new(); + + if value_to_counterparty > 0 { + txouts.push((TxOut { + script_pubkey: counterparty_shutdown_script, + value: value_to_counterparty + }, ())); + } + + if value_to_holder > 0 { + txouts.push((TxOut { + script_pubkey: holder_shutdown_script, + value: value_to_holder + }, ())); + } + + transaction_utils::sort_outputs(&mut txouts, |_, _| { cmp::Ordering::Equal }); // Ordering doesnt matter if they used our pubkey... + + let mut outputs: Vec = Vec::new(); + for out in txouts.drain(..) { + outputs.push(out.0); + } + + Transaction { + version: 2, + lock_time: 0, + input: txins, + output: outputs, + } +} + /// Implements the per-commitment secret storage scheme from /// [BOLT 3](https://github.com/lightningnetwork/lightning-rfc/blob/dcbf8583976df087c79c3ce0b535311212e6812d/03-transactions.md#efficient-per-commitment-secret-storage). /// diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs index 0481a93fc..2c835080a 100644 --- a/lightning/src/ln/channel.rs +++ b/lightning/src/ln/channel.rs @@ -8,7 +8,7 @@ // licenses. use bitcoin::blockdata::script::{Script,Builder}; -use bitcoin::blockdata::transaction::{TxIn, TxOut, Transaction, SigHashType}; +use bitcoin::blockdata::transaction::{Transaction, SigHashType}; use bitcoin::util::bip143; use bitcoin::consensus::encode; @@ -28,14 +28,13 @@ use ln::msgs; use ln::msgs::{DecodeError, OptionalField, DataLossProtect}; use ln::script::ShutdownScript; use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, BREAKDOWN_TIMEOUT, MIN_CLTV_EXPIRY_DELTA, MAX_LOCAL_BREAKDOWN_TIMEOUT}; -use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, CommitmentTransaction, HolderCommitmentTransaction, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, MAX_HTLCS, get_commitment_transaction_number_obscure_factor}; +use ln::chan_utils::{CounterpartyCommitmentSecrets, TxCreationKeys, HTLCOutputInCommitment, HTLC_SUCCESS_TX_WEIGHT, HTLC_TIMEOUT_TX_WEIGHT, make_funding_redeemscript, ChannelPublicKeys, CommitmentTransaction, HolderCommitmentTransaction, ChannelTransactionParameters, CounterpartyChannelTransactionParameters, MAX_HTLCS, get_commitment_transaction_number_obscure_factor, build_closing_transaction}; use ln::chan_utils; use chain::BestBlock; use chain::chaininterface::{FeeEstimator,ConfirmationTarget}; use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER}; use chain::transaction::{OutPoint, TransactionData}; use chain::keysinterface::{Sign, KeysInterface}; -use util::transaction_utils; use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter}; use util::logger::Logger; use util::errors::APIError; @@ -1287,62 +1286,36 @@ impl Channel { #[inline] fn build_closing_transaction(&self, proposed_total_fee_satoshis: u64, skip_remote_output: bool) -> (Transaction, u64) { - let txins = { - let mut ins: Vec = Vec::new(); - ins.push(TxIn { - previous_output: self.funding_outpoint().into_bitcoin_outpoint(), - script_sig: Script::new(), - sequence: 0xffffffff, - witness: Vec::new(), - }); - ins - }; - assert!(self.pending_inbound_htlcs.is_empty()); assert!(self.pending_outbound_htlcs.is_empty()); assert!(self.pending_update_fee.is_none()); - let mut txouts: Vec<(TxOut, ())> = Vec::new(); let mut total_fee_satoshis = proposed_total_fee_satoshis; - let value_to_self: i64 = (self.value_to_self_msat as i64) / 1000 - if self.is_outbound() { total_fee_satoshis as i64 } else { 0 }; - let value_to_remote: i64 = ((self.channel_value_satoshis * 1000 - self.value_to_self_msat) as i64 / 1000) - if self.is_outbound() { 0 } else { total_fee_satoshis as i64 }; + let mut value_to_holder: i64 = (self.value_to_self_msat as i64) / 1000 - if self.is_outbound() { total_fee_satoshis as i64 } else { 0 }; + let mut value_to_counterparty: i64 = ((self.channel_value_satoshis * 1000 - self.value_to_self_msat) as i64 / 1000) - if self.is_outbound() { 0 } else { total_fee_satoshis as i64 }; - if value_to_self < 0 { + if value_to_holder < 0 { assert!(self.is_outbound()); - total_fee_satoshis += (-value_to_self) as u64; - } else if value_to_remote < 0 { + total_fee_satoshis += (-value_to_holder) as u64; + } else if value_to_counterparty < 0 { assert!(!self.is_outbound()); - total_fee_satoshis += (-value_to_remote) as u64; + total_fee_satoshis += (-value_to_counterparty) as u64; } - if !skip_remote_output && value_to_remote as u64 > self.holder_dust_limit_satoshis { - txouts.push((TxOut { - script_pubkey: self.counterparty_shutdown_scriptpubkey.clone().unwrap(), - value: value_to_remote as u64 - }, ())); + if skip_remote_output || value_to_counterparty as u64 <= self.holder_dust_limit_satoshis { + value_to_counterparty = 0; } - assert!(self.shutdown_scriptpubkey.is_some()); - if value_to_self as u64 > self.holder_dust_limit_satoshis { - txouts.push((TxOut { - script_pubkey: self.get_closing_scriptpubkey(), - value: value_to_self as u64 - }, ())); + if value_to_holder as u64 <= self.holder_dust_limit_satoshis { + value_to_holder = 0; } - transaction_utils::sort_outputs(&mut txouts, |_, _| { cmp::Ordering::Equal }); // Ordering doesnt matter if they used our pubkey... - - let mut outputs: Vec = Vec::new(); - for out in txouts.drain(..) { - outputs.push(out.0); - } + assert!(self.shutdown_scriptpubkey.is_some()); + let holder_shutdown_script = self.get_closing_scriptpubkey(); + let counterparty_shutdown_script = self.counterparty_shutdown_scriptpubkey.clone().unwrap(); + let funding_outpoint = self.funding_outpoint().into_bitcoin_outpoint(); - (Transaction { - version: 2, - lock_time: 0, - input: txins, - output: outputs, - }, total_fee_satoshis) + (build_closing_transaction(value_to_holder as u64, value_to_counterparty as u64, holder_shutdown_script, counterparty_shutdown_script, funding_outpoint), total_fee_satoshis) } fn funding_outpoint(&self) -> OutPoint { -- 2.39.5