X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fln%2Fchan_utils.rs;h=df0378938b42eeb0b1ff0fbd1413f6f140617a12;hb=7544030bb63fee6484fc178bb2ac8f382fe3b5b1;hp=722693a430e57ebe8f5edae4c464ea335a1d5299;hpb=a447965b80ed763aea77b46aecaed9e94e292501;p=rust-lightning

diff --git a/lightning/src/ln/chan_utils.rs b/lightning/src/ln/chan_utils.rs
index 722693a4..df037893 100644
--- a/lightning/src/ln/chan_utils.rs
+++ b/lightning/src/ln/chan_utils.rs
@@ -42,6 +42,12 @@ use chain;
 use util::crypto::sign;
 
 pub(crate) const MAX_HTLCS: u16 = 483;
+pub(crate) const OFFERED_HTLC_SCRIPT_WEIGHT: usize = 133;
+pub(crate) const OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS: usize = 136;
+// The weight of `accepted_htlc_script` can vary in function of its CLTV argument value. We define a
+// range that encompasses both its non-anchors and anchors variants.
+pub(crate) const MIN_ACCEPTED_HTLC_SCRIPT_WEIGHT: usize = 136;
+pub(crate) const MAX_ACCEPTED_HTLC_SCRIPT_WEIGHT: usize = 143;
 
 /// Gets the weight for an HTLC-Success transaction.
 #[inline]
@@ -60,18 +66,72 @@ pub fn htlc_timeout_tx_weight(opt_anchors: bool) -> u64 {
 }
 
 #[derive(PartialEq)]
-pub(crate) enum HTLCType {
-	AcceptedHTLC,
-	OfferedHTLC
+pub(crate) enum HTLCClaim {
+	OfferedTimeout,
+	OfferedPreimage,
+	AcceptedTimeout,
+	AcceptedPreimage,
+	Revocation,
 }
 
-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)
+impl HTLCClaim {
+	/// Check if a given input witness attempts to claim a HTLC.
+	pub(crate) fn from_witness(witness: &Witness) -> Option<Self> {
+		debug_assert_eq!(OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS, MIN_ACCEPTED_HTLC_SCRIPT_WEIGHT);
+		if witness.len() < 2 {
+			return None;
+		}
+		let witness_script = witness.last().unwrap();
+		let second_to_last = witness.second_to_last().unwrap();
+		if witness_script.len() == OFFERED_HTLC_SCRIPT_WEIGHT {
+			if witness.len() == 3 && second_to_last.len() == 33 {
+				// <revocation sig> <revocationpubkey> <witness_script>
+				Some(Self::Revocation)
+			} else if witness.len() == 3 && second_to_last.len() == 32 {
+				// <remotehtlcsig> <payment_preimage> <witness_script>
+				Some(Self::OfferedPreimage)
+			} else if witness.len() == 5 && second_to_last.len() == 0 {
+				// 0 <remotehtlcsig> <localhtlcsig> <> <witness_script>
+				Some(Self::OfferedTimeout)
+			} else {
+				None
+			}
+		} else if witness_script.len() == OFFERED_HTLC_SCRIPT_WEIGHT_ANCHORS {
+			// It's possible for the weight of `offered_htlc_script` and `accepted_htlc_script` to
+			// match so we check for both here.
+			if witness.len() == 3 && second_to_last.len() == 33 {
+				// <revocation sig> <revocationpubkey> <witness_script>
+				Some(Self::Revocation)
+			} else if witness.len() == 3 && second_to_last.len() == 32 {
+				// <remotehtlcsig> <payment_preimage> <witness_script>
+				Some(Self::OfferedPreimage)
+			} else if witness.len() == 5 && second_to_last.len() == 0 {
+				// 0 <remotehtlcsig> <localhtlcsig> <> <witness_script>
+				Some(Self::OfferedTimeout)
+			} else if witness.len() == 3 && second_to_last.len() == 0 {
+				// <remotehtlcsig> <> <witness_script>
+				Some(Self::AcceptedTimeout)
+			} else if witness.len() == 5 && second_to_last.len() == 32 {
+				// 0 <remotehtlcsig> <localhtlcsig> <payment_preimage> <witness_script>
+				Some(Self::AcceptedPreimage)
+			} else {
+				None
+			}
+		} else if witness_script.len() > MIN_ACCEPTED_HTLC_SCRIPT_WEIGHT &&
+			witness_script.len() <= MAX_ACCEPTED_HTLC_SCRIPT_WEIGHT {
+			// Handle remaining range of ACCEPTED_HTLC_SCRIPT_WEIGHT.
+			if witness.len() == 3 && second_to_last.len() == 33 {
+				// <revocation sig> <revocationpubkey> <witness_script>
+				Some(Self::Revocation)
+			} else if witness.len() == 3 && second_to_last.len() == 0 {
+				// <remotehtlcsig> <> <witness_script>
+				Some(Self::AcceptedTimeout)
+			} else if witness.len() == 5 && second_to_last.len() == 32 {
+				// 0 <remotehtlcsig> <localhtlcsig> <payment_preimage> <witness_script>
+				Some(Self::AcceptedPreimage)
+			} else {
+				None
+			}
 		} else {
 			None
 		}
@@ -285,7 +345,7 @@ 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 +380,7 @@ 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.