Handle fallible release_commitment_secret

Author: alecchendev

lightning/src/ln/channel.rs

@@ -5499,26 +5499,35 @@ impl<SP: Deref> Channel<SP> where
 
 	fn get_last_revoke_and_ack<L: Deref>(&mut self, logger: &L) -> Option<msgs::RevokeAndACK> where L::Target: Logger {
 		debug_assert!(self.context.holder_commitment_point.transaction_number() <= INITIAL_COMMITMENT_NUMBER - 2);
-		let per_commitment_secret = self.context.holder_signer.as_ref().release_commitment_secret(self.context.holder_commitment_point.transaction_number() + 2);
-		if let HolderCommitmentPoint::Available { transaction_number: _, current, next: _ } = self.context.holder_commitment_point {
+		let per_commitment_secret = self.context.holder_signer.as_ref()
+			.release_commitment_secret(self.context.holder_commitment_point.transaction_number() + 2).ok();
+		if let (HolderCommitmentPoint::Available { current, .. }, Some(per_commitment_secret)) =
+			(self.context.holder_commitment_point, per_commitment_secret) {
 			self.context.signer_pending_revoke_and_ack = false;
-			Some(msgs::RevokeAndACK {
+			return Some(msgs::RevokeAndACK {
 				channel_id: self.context.channel_id,
 				per_commitment_secret,
 				next_per_commitment_point: current,
 				#[cfg(taproot)]
 				next_local_nonce: None,
 			})
-		} else {
-			#[cfg(not(async_signing))] {
-				panic!("Holder commitment point must be Available when generating revoke_and_ack");
-			}
-			#[cfg(async_signing)] {
-				log_trace!(logger, "Last revoke-and-ack pending in channel {} for sequence {} because the next per-commitment point is not available",
-					&self.context.channel_id(), self.context.holder_commitment_point.transaction_number());
-				self.context.signer_pending_revoke_and_ack = true;
-				None
-			}
+		}
+
+		if !self.context.holder_commitment_point.is_available() {
+			log_trace!(logger, "Last revoke-and-ack pending in channel {} for sequence {} because the next per-commitment point is not available",
+				&self.context.channel_id(), self.context.holder_commitment_point.transaction_number());
+		}
+		if per_commitment_secret.is_none() {
+			log_trace!(logger, "Last revoke-and-ack pending in channel {} for sequence {} because the next per-commitment secret for {} is not available",
+				&self.context.channel_id(), self.context.holder_commitment_point.transaction_number(),
+				self.context.holder_commitment_point.transaction_number() + 2);
+		}
+		#[cfg(not(async_signing))] {
+			panic!("Holder commitment point and per commitment secret must be available when generating revoke_and_ack");
+		}
+		#[cfg(async_signing)] {
+			self.context.signer_pending_revoke_and_ack = true;
+			None
 		}
 	}
 

lightning/src/ln/functional_tests.rs

@@ -1474,7 +1474,7 @@ fn test_fee_spike_violation_fails_htlc() {
 
 		let pubkeys = chan_signer.as_ref().pubkeys();
 		(pubkeys.revocation_basepoint, pubkeys.htlc_basepoint,
-		 chan_signer.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER),
+		 chan_signer.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER).unwrap(),
 		 chan_signer.as_ref().get_per_commitment_point(INITIAL_COMMITMENT_NUMBER - 2, &secp_ctx).unwrap(),
 		 chan_signer.as_ref().pubkeys().funding_pubkey)
 	};
@@ -7860,15 +7860,15 @@ fn test_counterparty_raa_skip_no_crash() {
 
 		// Make signer believe we got a counterparty signature, so that it allows the revocation
 		keys.as_ecdsa().unwrap().get_enforcement_state().last_holder_commitment -= 1;
-		per_commitment_secret = keys.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER);
+		per_commitment_secret = keys.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER).unwrap();
 
 		// Must revoke without gaps
 		keys.as_ecdsa().unwrap().get_enforcement_state().last_holder_commitment -= 1;
-		keys.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER - 1);
+		keys.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER - 1).unwrap();
 
 		keys.as_ecdsa().unwrap().get_enforcement_state().last_holder_commitment -= 1;
 		next_per_commitment_point = PublicKey::from_secret_key(&Secp256k1::new(),
-			&SecretKey::from_slice(&keys.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER - 2)).unwrap());
+			&SecretKey::from_slice(&keys.as_ref().release_commitment_secret(INITIAL_COMMITMENT_NUMBER - 2).unwrap()).unwrap());
 	}
 
 	nodes[1].node.handle_revoke_and_ack(&nodes[0].node.get_our_node_id(),

lightning/src/sign/mod.rs

@@ -749,7 +749,7 @@ pub trait ChannelSigner {
 	///
 	/// Note that the commitment number starts at `(1 << 48) - 1` and counts backwards.
 	// TODO: return a Result so we can signal a validation error
-	fn release_commitment_secret(&self, idx: u64) -> [u8; 32];
+	fn release_commitment_secret(&self, idx: u64) -> Result<[u8; 32], ()>;
 
 	/// Validate the counterparty's signatures on the holder commitment transaction and HTLCs.
 	///
@@ -1358,8 +1358,8 @@ impl ChannelSigner for InMemorySigner {
 		Ok(PublicKey::from_secret_key(secp_ctx, &commitment_secret))
 	}
 
-	fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
-		chan_utils::build_commitment_secret(&self.commitment_seed, idx)
+	fn release_commitment_secret(&self, idx: u64) -> Result<[u8; 32], ()> {
+		Ok(chan_utils::build_commitment_secret(&self.commitment_seed, idx))
 	}
 
 	fn validate_holder_commitment(

lightning/src/util/test_channel_signer.rs

@@ -172,7 +172,7 @@ impl ChannelSigner for TestChannelSigner {
 		self.inner.get_per_commitment_point(idx, secp_ctx)
 	}
 
-	fn release_commitment_secret(&self, idx: u64) -> [u8; 32] {
+	fn release_commitment_secret(&self, idx: u64) -> Result<[u8; 32], ()> {
 		{
 			let mut state = self.state.lock().unwrap();
 			assert!(idx == state.last_holder_revoked_commitment || idx == state.last_holder_revoked_commitment - 1, "can only revoke the current or next unrevoked commitment - trying {}, last revoked {}", idx, state.last_holder_revoked_commitment);