Update HTLC script detection to check for anchor output variants

Author: wpaulino

lightning/src/chain/channelmonitor.rs

@@ -3131,7 +3131,11 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		'outer_loop: for input in &tx.input {
 			let mut payment_data = None;
 			let witness_items = input.witness.len();
-			let htlctype = input.witness.last().map(|w| w.len()).and_then(HTLCType::scriptlen_to_htlctype);
+			let htlctype = if let Some(last_item) = input.witness.last() {
+				HTLCType::scriptlen_to_htlctype(last_item.len(), self.onchain_tx_handler.opt_anchors())
+			} else {
+				None
+			};
 			let prev_last_witness_len = input.witness.second_to_last().map(|w| w.len()).unwrap_or(0);
 			let revocation_sig_claim = (witness_items == 3 && htlctype == Some(HTLCType::OfferedHTLC) && prev_last_witness_len == 33)
 				|| (witness_items == 3 && htlctype == Some(HTLCType::AcceptedHTLC) && prev_last_witness_len == 33);

lightning/src/ln/chan_utils.rs

@@ -67,13 +67,25 @@ pub(crate) enum HTLCType {
 
 impl HTLCType {
 	/// Check if a given tx witnessScript len matchs one of a pre-signed HTLC
-	pub(crate) fn scriptlen_to_htlctype(witness_script_len: usize) ->  Option<HTLCType> {
-		if witness_script_len == 133 {
-			Some(HTLCType::OfferedHTLC)
-		} else if witness_script_len >= 136 && witness_script_len <= 139 {
-			Some(HTLCType::AcceptedHTLC)
+	pub(crate) fn scriptlen_to_htlctype(witness_script_len: usize, opt_anchors: bool) ->  Option<HTLCType> {
+		if opt_anchors {
+			if witness_script_len == 136 {
+				Some(HTLCType::OfferedHTLC)
+			} else if witness_script_len >= 139 && witness_script_len <= 143 {
+				// Variable length due to CLTV expiry pushed as a VarInt.
+				Some(HTLCType::AcceptedHTLC)
+			} else {
+				None
+			}
 		} else {
-			None
+			if witness_script_len == 133 {
+				Some(HTLCType::OfferedHTLC)
+			} else if witness_script_len >= 136 && witness_script_len <= 140 {
+				// Variable length due to CLTV expiry pushed as a VarInt.
+				Some(HTLCType::AcceptedHTLC)
+			} else {
+				None
+			}
 		}
 	}
 }
@@ -285,7 +297,7 @@ pub fn derive_public_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1<T>, per_com
 
 /// Derives a per-commitment-transaction revocation key from its constituent parts.
 ///
-/// Only the cheating participant owns a valid witness to propagate a revoked 
+/// Only the cheating participant owns a valid witness to propagate a revoked
 /// commitment transaction, thus per_commitment_secret always come from cheater
 /// and revocation_base_secret always come from punisher, which is the broadcaster
 /// of the transaction spending with this key knowledge.
@@ -320,7 +332,7 @@ pub fn derive_private_revocation_key<T: secp256k1::Signing>(secp_ctx: &Secp256k1
 /// the public equivalend of derive_private_revocation_key - using only public keys to derive a
 /// public key instead of private keys.
 ///
-/// Only the cheating participant owns a valid witness to propagate a revoked 
+/// Only the cheating participant owns a valid witness to propagate a revoked
 /// commitment transaction, thus per_commitment_point always come from cheater
 /// and revocation_base_point always come from punisher, which is the broadcaster
 /// of the transaction spending with this key knowledge.

lightning/src/ln/functional_tests.rs

@@ -9454,7 +9454,7 @@ fn test_invalid_funding_tx() {
 	// a panic as we'd try to extract a 32 byte preimage from a witness element without checking
 	// its length.
 	let mut wit_program: Vec<u8> = channelmonitor::deliberately_bogus_accepted_htlc_witness_program();
-	assert!(chan_utils::HTLCType::scriptlen_to_htlctype(wit_program.len()).unwrap() ==
+	assert!(chan_utils::HTLCType::scriptlen_to_htlctype(wit_program.len(), false).unwrap() ==
 		chan_utils::HTLCType::AcceptedHTLC);
 
 	let wit_program_script: Script = wit_program.clone().into();

lightning/src/util/macro_logger.rs

@@ -90,22 +90,30 @@ pub(crate) struct DebugTx<'a>(pub &'a Transaction);
 impl<'a> core::fmt::Display for DebugTx<'a> {
 	fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
 		if self.0.input.len() >= 1 && self.0.input.iter().any(|i| !i.witness.is_empty()) {
-			if self.0.input.len() == 1 && self.0.input[0].witness.last().unwrap().len() == 71 &&
+			let witness_script_len = self.0.input[0].witness.last().unwrap().len();
+			let is_offered_htlc_script = HTLCType::scriptlen_to_htlctype(witness_script_len, false) == Some(HTLCType::OfferedHTLC) ||
+				HTLCType::scriptlen_to_htlctype(witness_script_len, true) == Some(HTLCType::OfferedHTLC);
+			let is_accepted_htlc_script = HTLCType::scriptlen_to_htlctype(witness_script_len, false) == Some(HTLCType::AcceptedHTLC) ||
+				HTLCType::scriptlen_to_htlctype(witness_script_len, true) == Some(HTLCType::AcceptedHTLC);
+			if self.0.input.len() == 1 && witness_script_len == 71 &&
 					(self.0.input[0].sequence.0 >> 8*3) as u8 == 0x80 {
 				write!(f, "commitment tx ")?;
-			} else if self.0.input.len() == 1 && self.0.input[0].witness.last().unwrap().len() == 71 {
+			} else if self.0.input.len() == 1 && witness_script_len == 71 {
 				write!(f, "closing tx ")?;
-			} else if self.0.input.len() == 1 && HTLCType::scriptlen_to_htlctype(self.0.input[0].witness.last().unwrap().len()) == Some(HTLCType::OfferedHTLC) &&
-					self.0.input[0].witness.len() == 5 {
+			} else if is_offered_htlc_script && self.0.input[0].witness.len() == 5 {
 				write!(f, "HTLC-timeout tx ")?;
-			} else if self.0.input.len() == 1 && HTLCType::scriptlen_to_htlctype(self.0.input[0].witness.last().unwrap().len()) == Some(HTLCType::AcceptedHTLC) &&
-					self.0.input[0].witness.len() == 5 {
+			} else if is_accepted_htlc_script && self.0.input[0].witness.len() == 5 {
 				write!(f, "HTLC-success tx ")?;
 			} else {
 				for inp in &self.0.input {
 					if !inp.witness.is_empty() {
-						if HTLCType::scriptlen_to_htlctype(inp.witness.last().unwrap().len()) == Some(HTLCType::OfferedHTLC) { write!(f, "preimage-")?; break }
-						else if HTLCType::scriptlen_to_htlctype(inp.witness.last().unwrap().len()) == Some(HTLCType::AcceptedHTLC) { write!(f, "timeout-")?; break }
+						let witness_script_len = inp.witness.last().unwrap().len();
+						let is_offered_htlc_script = HTLCType::scriptlen_to_htlctype(witness_script_len, false) == Some(HTLCType::OfferedHTLC) ||
+							HTLCType::scriptlen_to_htlctype(witness_script_len, true) == Some(HTLCType::OfferedHTLC);
+						let is_accepted_htlc_script = HTLCType::scriptlen_to_htlctype(witness_script_len, false) == Some(HTLCType::AcceptedHTLC) ||
+							HTLCType::scriptlen_to_htlctype(witness_script_len, true) == Some(HTLCType::AcceptedHTLC);
+						if is_offered_htlc_script  { write!(f, "preimage-")?; break }
+						else if is_accepted_htlc_script { write!(f, "timeout-")?; break }
 					}
 				}
 				write!(f, "tx ")?;