From: Antoine Riard <ariard@student.42.fr>
Date: Tue, 24 Mar 2020 02:17:46 +0000 (-0400)
Subject: Cache remote HTLC inside OnchainTxHandler::RemoteTxCache
X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=6c78c6da7788eb351a368302c1d32c959b5fc93f;p=rust-lightning

Cache remote HTLC inside OnchainTxHandler::RemoteTxCache

As we can't predict if any and which revoked commitment tx is
going to appear onchain we have by design to cache all htlc information
to regenerate htlc script if needed.
---

diff --git a/lightning/src/ln/channelmonitor.rs b/lightning/src/ln/channelmonitor.rs
index 75bf6d7c6..a818e0702 100644
--- a/lightning/src/ln/channelmonitor.rs
+++ b/lightning/src/ln/channelmonitor.rs
@@ -1186,7 +1186,7 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 		log_trace!(self, "New potential remote commitment transaction: {}", encode::serialize_hex(unsigned_commitment_tx));
 		self.prev_remote_commitment_txid = self.current_remote_commitment_txid.take();
 		self.current_remote_commitment_txid = Some(new_txid);
-		self.remote_claimable_outpoints.insert(new_txid, htlc_outputs);
+		self.remote_claimable_outpoints.insert(new_txid, htlc_outputs.clone());
 		self.current_remote_commitment_number = commitment_number;
 		//TODO: Merge this into the other per-remote-transaction output storage stuff
 		match self.their_cur_revocation_points {
@@ -1207,6 +1207,13 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 				self.their_cur_revocation_points = Some((commitment_number, their_revocation_point, None));
 			}
 		}
+		let mut htlcs = Vec::with_capacity(htlc_outputs.len());
+		for htlc in htlc_outputs {
+			if htlc.0.transaction_output_index.is_some() {
+				htlcs.push(htlc.0);
+			}
+		}
+		self.onchain_tx_handler.provide_latest_remote_tx(new_txid, htlcs);
 	}
 
 	/// Informs this monitor of the latest local (ie broadcastable) commitment transaction. The
diff --git a/lightning/src/ln/onchaintx.rs b/lightning/src/ln/onchaintx.rs
index c57b11aaf..bdb2b952a 100644
--- a/lightning/src/ln/onchaintx.rs
+++ b/lightning/src/ln/onchaintx.rs
@@ -17,7 +17,7 @@ use bitcoin::secp256k1::key::PublicKey;
 use ln::msgs::DecodeError;
 use ln::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER, InputMaterial, ClaimRequest};
 use ln::channelmanager::PaymentPreimage;
-use ln::chan_utils::{HTLCType, LocalCommitmentTransaction};
+use ln::chan_utils::{HTLCType, LocalCommitmentTransaction, HTLCOutputInCommitment};
 use chain::chaininterface::{FeeEstimator, BroadcasterInterface, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
 use chain::keysinterface::ChannelKeys;
 use util::logger::Logger;
@@ -53,7 +53,8 @@ enum OnchainEvent {
 /// remote outputs, either justice or preimage/timeout transactions.
 struct RemoteTxCache {
 	remote_delayed_payment_base_key: PublicKey,
-	remote_htlc_base_key: PublicKey
+	remote_htlc_base_key: PublicKey,
+	per_htlc: HashMap<Sha256dHash, Vec<(HTLCOutputInCommitment)>>
 }
 
 /// Higher-level cache structure needed to re-generate bumped claim txn if needed
@@ -253,6 +254,14 @@ impl<ChanSigner: ChannelKeys + Writeable> OnchainTxHandler<ChanSigner> {
 
 		self.remote_tx_cache.remote_delayed_payment_base_key.write(writer)?;
 		self.remote_tx_cache.remote_htlc_base_key.write(writer)?;
+		writer.write_all(&byte_utils::be64_to_array(self.remote_tx_cache.per_htlc.len() as u64))?;
+		for (ref txid, ref htlcs) in self.remote_tx_cache.per_htlc.iter() {
+			writer.write_all(&txid[..])?;
+			writer.write_all(&byte_utils::be64_to_array(htlcs.len() as u64))?;
+			for &ref htlc in htlcs.iter() {
+				htlc.write(writer)?;
+			}
+		}
 		self.remote_csv.write(writer)?;
 
 		self.key_storage.write(writer)?;
@@ -306,9 +315,24 @@ impl<ChanSigner: ChannelKeys + Readable> ReadableArgs<Arc<Logger>> for OnchainTx
 		let remote_tx_cache = {
 			let remote_delayed_payment_base_key = Readable::read(reader)?;
 			let remote_htlc_base_key = Readable::read(reader)?;
+			let per_htlc_len: u64 = Readable::read(reader)?;
+			let mut per_htlc = HashMap::with_capacity(cmp::min(per_htlc_len as usize, MAX_ALLOC_SIZE / 64));
+			for _  in 0..per_htlc_len {
+				let txid: Sha256dHash = Readable::read(reader)?;
+				let htlcs_count: u64 = Readable::read(reader)?;
+				let mut htlcs = Vec::with_capacity(cmp::min(htlcs_count as usize, MAX_ALLOC_SIZE / 32));
+				for _ in 0..htlcs_count {
+					let htlc = Readable::read(reader)?;
+					htlcs.push(htlc);
+				}
+				if let Some(_) = per_htlc.insert(txid, htlcs) {
+					return Err(DecodeError::InvalidValue);
+				}
+			}
 			RemoteTxCache {
 				remote_delayed_payment_base_key,
 				remote_htlc_base_key,
+				per_htlc,
 			}
 		};
 		let remote_csv = Readable::read(reader)?;
@@ -385,6 +409,7 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 		let remote_tx_cache = RemoteTxCache {
 			remote_delayed_payment_base_key,
 			remote_htlc_base_key,
+			per_htlc: HashMap::new(),
 		};
 
 		OnchainTxHandler {
@@ -903,6 +928,10 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 		}
 	}
 
+	pub(super) fn provide_latest_remote_tx(&mut self, commitment_txid: Sha256dHash, htlcs: Vec<HTLCOutputInCommitment>) {
+		self.remote_tx_cache.per_htlc.insert(commitment_txid, htlcs);
+	}
+
 	#[cfg(test)]
 	pub(super) fn get_fully_signed_copy_local_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
 		if let Some(ref mut local_commitment) = self.local_commitment {