fixup! Allow forwarding HTLCs that were constructed for previous config

Author: wpaulino

lightning/src/ln/channel.rs

@@ -4578,15 +4578,14 @@ impl<Signer: Sign> Channel<Signer> {
 	pub fn htlc_satisfies_config(
 		&self, htlc: &msgs::UpdateAddHTLC, amt_to_forward: u64, outgoing_cltv_value: u32,
 	) -> Result<(), (&'static str, u16)> {
-		let res = self.internal_htlc_satisfies_config(&htlc, amt_to_forward, outgoing_cltv_value, &self.config());
-		if res.is_ok() {
-			return res;
-		}
-		if let Some(prev_config) = self.prev_config() {
-			self.internal_htlc_satisfies_config(htlc, amt_to_forward, outgoing_cltv_value, &prev_config)
-		} else {
-			res
-		}
+		self.internal_htlc_satisfies_config(&htlc, amt_to_forward, outgoing_cltv_value, &self.config())
+			.or_else(|err| {
+				if let Some(prev_config) = self.prev_config() {
+					self.internal_htlc_satisfies_config(htlc, amt_to_forward, outgoing_cltv_value, &prev_config)
+				} else {
+					Err(err)
+				}
+			})
 	}
 
 	pub fn get_feerate(&self) -> u32 {

lightning/src/ln/channelmanager.rs

@@ -2261,7 +2261,15 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 							break Some((err, code, chan_update_opt));
 						}
 						chan_update_opt
-					} else { None };
+					} else {
+						if (msg.cltv_expiry as u64) < (*outgoing_cltv_value) as u64 + MIN_CLTV_EXPIRY_DELTA as u64 { // incorrect_cltv_expiry
+							break Some((
+								"Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta",
+								0x1000 | 13, None,
+							));
+						}
+						None
+					};
 
 					let cur_height = self.best_block.read().unwrap().height() + 1;
 					// Theoretically, channel counterparty shouldn't send us a HTLC expiring now,