f - Refactor setting of Channel::shutdown_scriptpubkey at shutdown

Author: jkczyz

lightning/src/ln/channel.rs

@@ -3275,15 +3275,16 @@ impl<Signer: Sign> Channel<Signer> {
 		// any further commitment updates after we set LocalShutdownSent.
 		let send_shutdown = (self.channel_state & ChannelState::LocalShutdownSent as u32) != ChannelState::LocalShutdownSent as u32;
 
-		let shutdown_scriptpubkey = match self.shutdown_scriptpubkey {
-			Some(_) => None,
+		let update_shutdown_script = match self.shutdown_scriptpubkey {
+			Some(_) => false,
 			None => {
 				assert!(send_shutdown);
 				let shutdown_scriptpubkey = keys_provider.get_shutdown_scriptpubkey();
 				if !shutdown_scriptpubkey.is_compatible(their_features) {
 					return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer. script: ({})", shutdown_scriptpubkey.clone().into_inner().to_bytes().to_hex())));
 				}
-				Some(shutdown_scriptpubkey)
+				self.shutdown_scriptpubkey = Some(shutdown_scriptpubkey);
+				true
 			},
 		};
 
@@ -3307,19 +3308,15 @@ impl<Signer: Sign> Channel<Signer> {
 			}
 		});
 
-		let monitor_update = match shutdown_scriptpubkey {
-			Some(shutdown_scriptpubkey) => {
-				self.shutdown_scriptpubkey = Some(shutdown_scriptpubkey);
-				self.latest_monitor_update_id += 1;
-				Some(ChannelMonitorUpdate {
-					update_id: self.latest_monitor_update_id,
-					updates: vec![ChannelMonitorUpdateStep::ShutdownScript {
-						scriptpubkey: self.get_closing_scriptpubkey(),
-					}],
-				})
-			},
-			None => None,
-		};
+		let monitor_update = if update_shutdown_script {
+			self.latest_monitor_update_id += 1;
+			Some(ChannelMonitorUpdate {
+				update_id: self.latest_monitor_update_id,
+				updates: vec![ChannelMonitorUpdateStep::ShutdownScript {
+					scriptpubkey: self.get_closing_scriptpubkey(),
+				}],
+			})
+		} else { None };
 		let shutdown = if send_shutdown {
 			Some(msgs::Shutdown {
 				channel_id: self.channel_id,
@@ -4471,31 +4468,28 @@ impl<Signer: Sign> Channel<Signer> {
 			return Err(APIError::ChannelUnavailable{err: "Cannot begin shutdown while peer is disconnected or we're waiting on a monitor update, maybe force-close instead?".to_owned()});
 		}
 
-		let shutdown_scriptpubkey = match self.shutdown_scriptpubkey {
-			Some(_) => None,
+		let update_shutdown_script = match self.shutdown_scriptpubkey {
+			Some(_) => false,
 			None => {
 				let shutdown_scriptpubkey = keys_provider.get_shutdown_scriptpubkey();
 				if !shutdown_scriptpubkey.is_compatible(their_features) {
 					return Err(APIError::APIMisuseError { err: format!("Provided a scriptpubkey format not accepted by peer. script: ({})", shutdown_scriptpubkey.clone().into_inner().to_bytes().to_hex()) });
 				}
-				Some(shutdown_scriptpubkey)
-			},
-		};
-
-		let monitor_update = match shutdown_scriptpubkey {
-			Some(shutdown_scriptpubkey) => {
 				self.shutdown_scriptpubkey = Some(shutdown_scriptpubkey);
-				self.latest_monitor_update_id += 1;
-				Some(ChannelMonitorUpdate {
-					update_id: self.latest_monitor_update_id,
-					updates: vec![ChannelMonitorUpdateStep::ShutdownScript {
-						scriptpubkey: self.get_closing_scriptpubkey(),
-					}],
-				})
+				true
 			},
-			None => None,
 		};
 
+		let monitor_update = if update_shutdown_script {
+			self.latest_monitor_update_id += 1;
+			Some(ChannelMonitorUpdate {
+				update_id: self.latest_monitor_update_id,
+				updates: vec![ChannelMonitorUpdateStep::ShutdownScript {
+					scriptpubkey: self.get_closing_scriptpubkey(),
+				}],
+			})
+		} else { None };
+
 		// From here on out, we may not fail!
 		if self.channel_state < ChannelState::FundingSent as u32 {
 			self.channel_state = ChannelState::ShutdownComplete as u32;