Use new get_commitment_transaction_number_obscure_factor utility function

Author: devrandom

lightning/src/ln/channel.rs

@@ -14,7 +14,7 @@ use bitcoin::blockdata::opcodes;
 use bitcoin::util::bip143;
 use bitcoin::consensus::encode;
 
-use bitcoin::hashes::{Hash, HashEngine};
+use bitcoin::hashes::Hash;
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
 
@@ -26,7 +26,7 @@ use ln::features::{ChannelFeatures, InitFeatures};
 use ln::msgs;
 use ln::msgs::{DecodeError, OptionalField, DataLossProtect};
 use ln::channelmanager::{PendingHTLCStatus, HTLCSource, HTLCFailReason, HTLCFailureMsg, PendingHTLCInfo, RAACommitmentOrder, PaymentPreimage, PaymentHash, BREAKDOWN_TIMEOUT, 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};
+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;
 use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, HTLC_FAIL_BACK_BUFFER};
@@ -795,29 +795,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		Ok(chan)
 	}
 
-	// Utilities to build transactions:
-
-	fn get_commitment_transaction_number_obscure_factor(&self) -> u64 {
-		let mut sha = Sha256::engine();
-
-		let counterparty_payment_point = &self.get_counterparty_pubkeys().payment_point.serialize();
-		if self.is_outbound() {
-			sha.input(&self.get_holder_pubkeys().payment_point.serialize());
-			sha.input(counterparty_payment_point);
-		} else {
-			sha.input(counterparty_payment_point);
-			sha.input(&self.get_holder_pubkeys().payment_point.serialize());
-		}
-		let res = Sha256::from_engine(sha).into_inner();
-
-		((res[26] as u64) << 5*8) |
-		((res[27] as u64) << 4*8) |
-		((res[28] as u64) << 3*8) |
-		((res[29] as u64) << 2*8) |
-		((res[30] as u64) << 1*8) |
-		((res[31] as u64) << 0*8)
-	}
-
 	/// Transaction nomenclature is somewhat confusing here as there are many different cases - a
 	/// transaction is referred to as "a's transaction" implying that a will be able to broadcast
 	/// the transaction. Thus, b will generally be sending a signature over such a transaction to
@@ -846,7 +823,7 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let mut local_htlc_total_msat = 0;
 		let mut value_to_self_msat_offset = 0;
 
-		log_trace!(logger, "Building commitment transaction number {} (really {} xor {}) for {}, generated by {} with fee {}...", commitment_number, (INITIAL_COMMITMENT_NUMBER - commitment_number), self.get_commitment_transaction_number_obscure_factor(), if local { "us" } else { "remote" }, if generated_by_local { "us" } else { "remote" }, feerate_per_kw);
+		log_trace!(logger, "Building commitment transaction number {} (really {} xor {}) for {}, generated by {} with fee {}...", commitment_number, (INITIAL_COMMITMENT_NUMBER - commitment_number), get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound()), if local { "us" } else { "remote" }, if generated_by_local { "us" } else { "remote" }, feerate_per_kw);
 
 		macro_rules! get_htlc_in_commitment {
 			($htlc: expr, $offered: expr) => {
@@ -1539,12 +1516,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 
 		let funding_redeemscript = self.get_funding_redeemscript();
 		let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
+		let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
 		let mut channel_monitor = ChannelMonitor::new(self.holder_keys.clone(),
 		                                              &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
 		                                              &self.destination_script, (funding_txo, funding_txo_script.clone()),
 		                                              &self.channel_transaction_parameters,
 		                                              funding_redeemscript.clone(), self.channel_value_satoshis,
-		                                              self.get_commitment_transaction_number_obscure_factor(),
+		                                              obscure_factor,
 		                                              holder_commitment_tx);
 
 		channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_commitment_txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);
@@ -1608,12 +1586,13 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 		let funding_redeemscript = self.get_funding_redeemscript();
 		let funding_txo = self.get_funding_txo().unwrap();
 		let funding_txo_script = funding_redeemscript.to_v0_p2wsh();
+		let obscure_factor = get_commitment_transaction_number_obscure_factor(&self.get_holder_pubkeys().payment_point, &self.get_counterparty_pubkeys().payment_point, self.is_outbound());
 		let mut channel_monitor = ChannelMonitor::new(self.holder_keys.clone(),
 		                                              &self.shutdown_pubkey, self.get_holder_selected_contest_delay(),
 		                                              &self.destination_script, (funding_txo, funding_txo_script),
 		                                              &self.channel_transaction_parameters,
 		                                              funding_redeemscript.clone(), self.channel_value_satoshis,
-		                                              self.get_commitment_transaction_number_obscure_factor(),
+		                                              obscure_factor,
 		                                              holder_commitment_tx);
 
 		channel_monitor.provide_latest_counterparty_commitment_tx(counterparty_initial_bitcoin_tx.txid, Vec::new(), self.cur_counterparty_commitment_transaction_number, self.counterparty_cur_commitment_point.unwrap(), logger);