Include the user channel id counter in Event::ChannelClosed

This makes it more practical for users to track channels using
their own IDs, especially across funding.

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -242,7 +242,7 @@ type ShutdownResult = (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource
 
 struct MsgHandleErrInternal {
 	err: msgs::LightningError,
-	chan_id: Option<[u8; 32]>, // If Some a channel of ours has been closed
+	chan_id: Option<([u8; 32], u64)>, // If Some a channel of ours has been closed
 	shutdown_finish: Option<(ShutdownResult, Option<msgs::ChannelUpdate>)>,
 }
 impl MsgHandleErrInternal {
@@ -278,7 +278,7 @@ impl MsgHandleErrInternal {
 		Self { err, chan_id: None, shutdown_finish: None }
 	}
 	#[inline]
-	fn from_finish_shutdown(err: String, channel_id: [u8; 32], shutdown_res: ShutdownResult, channel_update: Option<msgs::ChannelUpdate>) -> Self {
+	fn from_finish_shutdown(err: String, channel_id: [u8; 32], user_channel_id: u64, shutdown_res: ShutdownResult, channel_update: Option<msgs::ChannelUpdate>) -> Self {
 		Self {
 			err: LightningError {
 				err: err.clone(),
@@ -289,7 +289,7 @@ impl MsgHandleErrInternal {
 					},
 				},
 			},
-			chan_id: Some(channel_id),
+			chan_id: Some((channel_id, user_channel_id)),
 			shutdown_finish: Some((shutdown_res, channel_update)),
 		}
 	}
@@ -894,8 +894,11 @@ macro_rules! handle_error {
 							msg: update
 						});
 					}
-					if let Some(channel_id) = chan_id {
-						$self.pending_events.lock().unwrap().push(events::Event::ChannelClosed { channel_id,  reason: ClosureReason::ProcessingError { err: err.err.clone() } });
+					if let Some((channel_id, user_channel_id)) = chan_id {
+						$self.pending_events.lock().unwrap().push(events::Event::ChannelClosed {
+							channel_id, user_channel_id,
+							reason: ClosureReason::ProcessingError { err: err.err.clone() }
+						});
 					}
 				}
 
@@ -937,15 +940,17 @@ macro_rules! convert_chan_err {
 					$short_to_id.remove(&short_id);
 				}
 				let shutdown_res = $channel.force_shutdown(true);
-				(true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, shutdown_res, $self.get_channel_update_for_broadcast(&$channel).ok()))
+				(true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, $channel.get_user_id(),
+					shutdown_res, $self.get_channel_update_for_broadcast(&$channel).ok()))
 			},
 			ChannelError::CloseDelayBroadcast(msg) => {
 				log_error!($self.logger, "Channel {} need to be shutdown but closing transactions not broadcast due to {}", log_bytes!($channel_id[..]), msg);
 				if let Some(short_id) = $channel.get_short_channel_id() {
 					$short_to_id.remove(&short_id);
 				}
 				let shutdown_res = $channel.force_shutdown(false);
-				(true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, shutdown_res, $self.get_channel_update_for_broadcast(&$channel).ok()))
+				(true, MsgHandleErrInternal::from_finish_shutdown(msg, *$channel_id, $channel.get_user_id(),
+					shutdown_res, $self.get_channel_update_for_broadcast(&$channel).ok()))
 			}
 		}
 	}
@@ -1013,7 +1018,7 @@ macro_rules! handle_monitor_err {
 				// splitting hairs we'd prefer to claim payments that were to us, but we haven't
 				// given up the preimage yet, so might as well just wait until the payment is
 				// retried, avoiding the on-chain fees.
-				let res: Result<(), _> = Err(MsgHandleErrInternal::from_finish_shutdown("ChannelMonitor storage failure".to_owned(), *$chan_id,
+				let res: Result<(), _> = Err(MsgHandleErrInternal::from_finish_shutdown("ChannelMonitor storage failure".to_owned(), *$chan_id, $chan.get_user_id(),
 						$chan.force_shutdown(true), $self.get_channel_update_for_broadcast(&$chan).ok() ));
 				(res, true)
 			},
@@ -1402,7 +1407,11 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 			},
 			None => {},
 		}
-		pending_events_lock.push(events::Event::ChannelClosed { channel_id: channel.channel_id(), reason: closure_reason });
+		pending_events_lock.push(events::Event::ChannelClosed {
+			channel_id: channel.channel_id(),
+			user_channel_id: channel.get_user_id(),
+			reason: closure_reason
+		});
 	}
 
 	fn close_channel_internal(&self, channel_id: &[u8; 32], target_feerate_sats_per_1000_weight: Option<u32>) -> Result<(), APIError> {
@@ -2237,7 +2246,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 
 					(chan.get_outbound_funding_created(funding_transaction, funding_txo, &self.logger)
 						.map_err(|e| if let ChannelError::Close(msg) = e {
-							MsgHandleErrInternal::from_finish_shutdown(msg, chan.channel_id(), chan.force_shutdown(true), None)
+							MsgHandleErrInternal::from_finish_shutdown(msg, chan.channel_id(), chan.get_user_id(), chan.force_shutdown(true), None)
 						} else { unreachable!(); })
 					, chan)
 				},
@@ -2579,7 +2588,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 												channel_state.short_to_id.remove(&short_id);
 											}
 											// ChannelClosed event is generated by handle_error for us.
-											Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, channel.force_shutdown(true), self.get_channel_update_for_broadcast(&channel).ok()))
+											Err(MsgHandleErrInternal::from_finish_shutdown(msg, channel_id, channel.get_user_id(), channel.force_shutdown(true), self.get_channel_update_for_broadcast(&channel).ok()))
 										},
 										ChannelError::CloseDelayBroadcast(_) => { panic!("Wait is only generated on receipt of channel_reestablish, which is handled by try_chan_entry, we don't bother to support it here"); }
 									};
@@ -5618,6 +5627,7 @@ impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 					monitor.broadcast_latest_holder_commitment_txn(&args.tx_broadcaster, &args.logger);
 					channel_closures.push(events::Event::ChannelClosed {
 						channel_id: channel.channel_id(),
+						user_channel_id: channel.get_user_id(),
 						reason: ClosureReason::OutdatedChannelManager
 					});
 				} else {

lightning/src/util/events.rs

@@ -146,7 +146,10 @@ pub enum Event {
 		channel_value_satoshis: u64,
 		/// The script which should be used in the transaction output.
 		output_script: Script,
-		/// The value passed in to ChannelManager::create_channel
+		/// The `user_id` value passed in to [`ChannelManager::create_channel`], or 0 for an
+		/// inbound channel.
+		///
+		/// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
 		user_channel_id: u64,
 	},
 	/// Indicates we've received money! Just gotta dig out that payment preimage and feed it to
@@ -262,6 +265,12 @@ pub enum Event {
 		/// The channel_id of the channel which has been closed. Note that on-chain transactions
 		/// resolving the channel are likely still awaiting confirmation.
 		channel_id: [u8; 32],
+		/// The `user_id` value passed in to [`ChannelManager::create_channel`], or 0 for an
+		/// inbound channel. This will always be zero for objects serialized with LDK versions
+		/// prior to 0.0.102.
+		///
+		/// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
+		user_channel_id: u64,
 		/// The reason the channel was closed.
 		reason: ClosureReason
 	},
@@ -352,10 +361,11 @@ impl Writeable for Event {
 					(2, claim_from_onchain_tx, required),
 				});
 			},
-			&Event::ChannelClosed { ref channel_id, ref reason } => {
+			&Event::ChannelClosed { ref channel_id, ref user_channel_id, ref reason } => {
 				9u8.write(writer)?;
 				write_tlv_fields!(writer, {
 					(0, channel_id, required),
+					(1, user_channel_id, required),
 					(2, reason, required)
 				});
 			},
@@ -492,12 +502,15 @@ impl MaybeReadable for Event {
 				let f = || {
 					let mut channel_id = [0; 32];
 					let mut reason = None;
+					let mut user_channel_id_opt = None;
 					read_tlv_fields!(reader, {
 						(0, channel_id, required),
+						(1, user_channel_id_opt, option),
 						(2, reason, ignorable),
 					});
 					if reason.is_none() { return Ok(None); }
-					Ok(Some(Event::ChannelClosed { channel_id, reason: reason.unwrap() }))
+					let user_channel_id = if let Some(id) = user_channel_id_opt { id } else { 0 };
+					Ok(Some(Event::ChannelClosed { channel_id, user_channel_id, reason: reason.unwrap() }))
 				};
 				f()
 			},