Return ClosureReason from Channel chain update methods

This fixes a few `ClosureReason`s and allows us to have
finer-grained user-visible errors when a channel closes due to an
on-chain event.

lightning/src/ln/channel.rs

@@ -35,6 +35,7 @@ use chain::chaininterface::{FeeEstimator,ConfirmationTarget};
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateStep, LATENCY_GRACE_PERIOD_BLOCKS};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::{Sign, KeysInterface};
+use util::events::ClosureReason;
 use util::ser::{Readable, ReadableArgs, Writeable, Writer, VecWriter};
 use util::logger::Logger;
 use util::errors::APIError;
@@ -4117,7 +4118,7 @@ impl<Signer: Sign> Channel<Signer> {
 	/// In the first case, we store the confirmation height and calculating the short channel id.
 	/// In the second, we simply return an Err indicating we need to be force-closed now.
 	pub fn transactions_confirmed<L: Deref>(&mut self, block_hash: &BlockHash, height: u32, txdata: &TransactionData, logger: &L)
-			-> Result<Option<msgs::FundingLocked>, msgs::ErrorMessage> where L::Target: Logger {
+	-> Result<Option<msgs::FundingLocked>, ClosureReason> where L::Target: Logger {
 		let non_shutdown_state = self.channel_state & (!MULTI_STATE_FLAGS);
 		for &(index_in_block, tx) in txdata.iter() {
 			if let Some(funding_txo) = self.get_funding_txo() {
@@ -4138,10 +4139,8 @@ impl<Signer: Sign> Channel<Signer> {
 								panic!("Client called ChannelManager::funding_transaction_generated with bogus transaction!");
 							}
 							self.update_time_counter += 1;
-							return Err(msgs::ErrorMessage {
+							let err_reason = "funding tx had wrong script/value or output index";
-								channel_id: self.channel_id(),
+							return Err(ClosureReason::ProcessingError { err: err_reason.to_owned() });
-								data: "funding tx had wrong script/value or output index".to_owned()
-							});
 						} else {
 							if self.is_outbound() {
 								for input in tx.input.iter() {
@@ -4172,10 +4171,7 @@ impl<Signer: Sign> Channel<Signer> {
 				for inp in tx.input.iter() {
 					if inp.previous_output == funding_txo.into_bitcoin_outpoint() {
 						log_info!(logger, "Detected channel-closing tx {} spending {}:{}, closing channel {}", tx.txid(), inp.previous_output.txid, inp.previous_output.vout, log_bytes!(self.channel_id()));
-						return Err(msgs::ErrorMessage {
+						return Err(ClosureReason::CommitmentTxConfirmed);
-							channel_id: self.channel_id(),
-							data: "Commitment or closing transaction was confirmed on chain.".to_owned()
-						});
 					}
 				}
 			}
@@ -4195,7 +4191,7 @@ impl<Signer: Sign> Channel<Signer> {
 	/// May return some HTLCs (and their payment_hash) which have timed out and should be failed
 	/// back.
 	pub fn best_block_updated<L: Deref>(&mut self, height: u32, highest_header_time: u32, logger: &L)
-			-> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), msgs::ErrorMessage> where L::Target: Logger {
+	-> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), ClosureReason> where L::Target: Logger {
 		let mut timed_out_htlcs = Vec::new();
 		// This mirrors the check in ChannelManager::decode_update_add_htlc_onion, refusing to
 		// forward an HTLC when our counterparty should almost certainly just fail it for expiring
@@ -4236,10 +4232,9 @@ impl<Signer: Sign> Channel<Signer> {
 			// close the channel and hope we can get the latest state on chain (because presumably
 			// the funding transaction is at least still in the mempool of most nodes).
 			if funding_tx_confirmations < self.minimum_depth.unwrap() as i64 / 2 {
-				return Err(msgs::ErrorMessage {
+				let err_reason = format!("Funding transaction was un-confirmed. Locked at {} confs, now have {} confs.",
-					channel_id: self.channel_id(),
+					self.minimum_depth.unwrap(), funding_tx_confirmations);
-					data: format!("Funding transaction was un-confirmed. Locked at {} confs, now have {} confs.", self.minimum_depth.unwrap(), funding_tx_confirmations),
+				return Err(ClosureReason::ProcessingError { err: err_reason });
-				});
 			}
 		}
 
@@ -4249,7 +4244,7 @@ impl<Signer: Sign> Channel<Signer> {
 	/// Indicates the funding transaction is no longer confirmed in the main chain. This may
 	/// force-close the channel, but may also indicate a harmless reorganization of a block or two
 	/// before the channel has reached funding_locked and we can just wait for more blocks.
-	pub fn funding_transaction_unconfirmed<L: Deref>(&mut self, logger: &L) -> Result<(), msgs::ErrorMessage> where L::Target: Logger {
+	pub fn funding_transaction_unconfirmed<L: Deref>(&mut self, logger: &L) -> Result<(), ClosureReason> where L::Target: Logger {
 		if self.funding_tx_confirmation_height != 0 {
 			// We handle the funding disconnection by calling best_block_updated with a height one
 			// below where our funding was connected, implying a reorg back to conf_height - 1.

lightning/src/ln/channelmanager.rs

@@ -4850,7 +4850,7 @@ where
 	/// Calls a function which handles an on-chain event (blocks dis/connected, transactions
 	/// un/confirmed, etc) on each channel, handling any resulting errors or messages generated by
 	/// the function.
-	fn do_chain_event<FN: Fn(&mut Channel<Signer>) -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), msgs::ErrorMessage>>
+	fn do_chain_event<FN: Fn(&mut Channel<Signer>) -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), ClosureReason>>
 			(&self, height_opt: Option<u32>, f: FN) {
 		// Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
 		// during initialization prior to the chain_monitor being fully configured in some cases.
@@ -4895,7 +4895,7 @@ where
 						}
 						short_to_id.insert(channel.get_short_channel_id().unwrap(), channel.channel_id());
 					}
-				} else if let Err(e) = res {
+				} else if let Err(reason) = res {
 					if let Some(short_id) = channel.get_short_channel_id() {
 						short_to_id.remove(&short_id);
 					}
@@ -4907,10 +4907,14 @@ where
 							msg: update
 						});
 					}
-					self.issue_channel_close_events(channel, ClosureReason::CommitmentTxConfirmed);
+					let reason_message = format!("{}", reason);
+					self.issue_channel_close_events(channel, reason);
 					pending_msg_events.push(events::MessageSendEvent::HandleError {
 						node_id: channel.get_counterparty_node_id(),
-						action: msgs::ErrorAction::SendErrorMessage { msg: e },
+						action: msgs::ErrorAction::SendErrorMessage { msg: msgs::ErrorMessage {
+							channel_id: channel.channel_id(),
+							data: reason_message,
+						} },
 					});
 					return false;
 				}

lightning/src/ln/functional_test_utils.rs

@@ -1737,7 +1737,7 @@ pub fn handle_announce_close_broadcast_events<'a, 'b, 'c>(nodes: &Vec<Node<'a, '
 }
 
 pub fn get_announce_close_broadcast_events<'a, 'b, 'c>(nodes: &Vec<Node<'a, 'b, 'c>>, a: usize, b: usize)  {
-	handle_announce_close_broadcast_events(nodes, a, b, false, "Commitment or closing transaction was confirmed on chain.");
+	handle_announce_close_broadcast_events(nodes, a, b, false, "Channel closed because commitment or closing transaction was confirmed on chain.");
 }
 
 #[cfg(test)]

lightning/src/ln/functional_tests.rs

@@ -1207,7 +1207,7 @@ fn test_duplicate_htlc_different_direction_onchain() {
 			MessageSendEvent::BroadcastChannelUpdate { .. } => {},
 			MessageSendEvent::HandleError { node_id, action: msgs::ErrorAction::SendErrorMessage { ref msg } } => {
 				assert_eq!(node_id, nodes[1].node.get_our_node_id());
-				assert_eq!(msg.data, "Commitment or closing transaction was confirmed on chain.");
+				assert_eq!(msg.data, "Channel closed because commitment or closing transaction was confirmed on chain.");
 			},
 			MessageSendEvent::UpdateHTLCs { ref node_id, updates: msgs::CommitmentUpdate { ref update_add_htlcs, ref update_fulfill_htlcs, ref update_fail_htlcs, ref update_fail_malformed_htlcs, .. } } => {
 				assert!(update_add_htlcs.is_empty());
@@ -3017,7 +3017,7 @@ fn do_test_commitment_revoked_fail_backward_exhaustive(deliver_bs_raa: bool, use
 	match events[if deliver_bs_raa { 2 } else { 1 }] {
 		MessageSendEvent::HandleError { action: ErrorAction::SendErrorMessage { msg: msgs::ErrorMessage { channel_id, ref data } }, node_id: _ } => {
 			assert_eq!(channel_id, chan_2.2);
-			assert_eq!(data.as_str(), "Commitment or closing transaction was confirmed on chain.");
+			assert_eq!(data.as_str(), "Channel closed because commitment or closing transaction was confirmed on chain.");
 		},
 		_ => panic!("Unexpected event"),
 	}
@@ -8831,15 +8831,16 @@ fn test_invalid_funding_tx() {
 	assert_eq!(nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap()[0], tx);
 	nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().clear();
 
+	let expected_err = "funding tx had wrong script/value or output index";
 	confirm_transaction_at(&nodes[1], &tx, 1);
-	check_closed_event!(nodes[1], 1, ClosureReason::CommitmentTxConfirmed);
+	check_closed_event!(nodes[1], 1, ClosureReason::ProcessingError { err: expected_err.to_string() });
 	check_added_monitors!(nodes[1], 1);
 	let events_2 = nodes[1].node.get_and_clear_pending_msg_events();
 	assert_eq!(events_2.len(), 1);
 	if let MessageSendEvent::HandleError { node_id, action } = &events_2[0] {
 		assert_eq!(*node_id, nodes[0].node.get_our_node_id());
 		if let msgs::ErrorAction::SendErrorMessage { msg } = action {
-			assert_eq!(msg.data, "funding tx had wrong script/value or output index");
+			assert_eq!(msg.data, "Channel closed because of an exception: ".to_owned() + expected_err);
 		} else { panic!(); }
 	} else { panic!(); }
 	assert_eq!(nodes[1].node.list_channels().len(), 0);

lightning/src/ln/reorg_tests.rs

@@ -219,9 +219,9 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 			disconnect_all_blocks(&nodes[0]);
 		}
 		if connect_style == ConnectStyle::FullBlockViaListen && !use_funding_unconfirmed {
-			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Funding transaction was un-confirmed. Locked at 6 confs, now have 2 confs.");
+			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Channel closed because of an exception: Funding transaction was un-confirmed. Locked at 6 confs, now have 2 confs.");
 		} else {
-			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Funding transaction was un-confirmed. Locked at 6 confs, now have 0 confs.");
+			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Channel closed because of an exception: Funding transaction was un-confirmed. Locked at 6 confs, now have 0 confs.");
 		}
 		check_added_monitors!(nodes[1], 1);
 		{
@@ -287,9 +287,9 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 			disconnect_all_blocks(&nodes[0]);
 		}
 		if connect_style == ConnectStyle::FullBlockViaListen && !use_funding_unconfirmed {
-			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Funding transaction was un-confirmed. Locked at 6 confs, now have 2 confs.");
+			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Channel closed because of an exception: Funding transaction was un-confirmed. Locked at 6 confs, now have 2 confs.");
 		} else {
-			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Funding transaction was un-confirmed. Locked at 6 confs, now have 0 confs.");
+			handle_announce_close_broadcast_events(&nodes, 0, 1, true, "Channel closed because of an exception: Funding transaction was un-confirmed. Locked at 6 confs, now have 0 confs.");
 		}
 		check_added_monitors!(nodes[1], 1);
 		{
@@ -303,12 +303,13 @@ fn do_test_unconf_chan(reload_node: bool, reorg_after_reload: bool, use_funding_
 	*nodes[0].chain_monitor.expect_channel_force_closed.lock().unwrap() = Some((chan.2, true));
 	nodes[0].node.test_process_background_events(); // Required to free the pending background monitor update
 	check_added_monitors!(nodes[0], 1);
-	check_closed_event!(nodes[0], 1, ClosureReason::CommitmentTxConfirmed);
+	let expected_err = if connect_style == ConnectStyle::FullBlockViaListen && !use_funding_unconfirmed {
-	if connect_style == ConnectStyle::FullBlockViaListen && !use_funding_unconfirmed {
+		"Funding transaction was un-confirmed. Locked at 6 confs, now have 2 confs."
-		check_closed_event!(nodes[1], 1, ClosureReason::CounterpartyForceClosed { peer_msg: "Funding transaction was un-confirmed. Locked at 6 confs, now have 2 confs.".to_string() });
 	} else {
-		check_closed_event!(nodes[1], 1, ClosureReason::CounterpartyForceClosed { peer_msg: "Funding transaction was un-confirmed. Locked at 6 confs, now have 0 confs.".to_string() });
+		"Funding transaction was un-confirmed. Locked at 6 confs, now have 0 confs."
-	}
+	};
+	check_closed_event!(nodes[1], 1, ClosureReason::CounterpartyForceClosed { peer_msg: "Channel closed because of an exception: ".to_owned() + expected_err });
+	check_closed_event!(nodes[0], 1, ClosureReason::ProcessingError { err: expected_err.to_owned() });
 	assert_eq!(nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().len(), 1);
 	nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().clear();
 

lightning/src/util/events.rs

@@ -118,6 +118,27 @@ pub enum ClosureReason {
 	OutdatedChannelManager
 }
 
+impl core::fmt::Display for ClosureReason {
+	fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
+		f.write_str("Channel closed because ")?;
+		match self {
+			ClosureReason::CounterpartyForceClosed { peer_msg } => {
+				f.write_str("counterparty force-closed with message ")?;
+				f.write_str(&peer_msg)
+			},
+			ClosureReason::HolderForceClosed => f.write_str("user manually force-closed the channel"),
+			ClosureReason::CooperativeClosure => f.write_str("the channel was cooperatively closed"),
+			ClosureReason::CommitmentTxConfirmed => f.write_str("commitment or closing transaction was confirmed on chain."),
+			ClosureReason::ProcessingError { err } => {
+				f.write_str("of an exception: ")?;
+				f.write_str(&err)
+			},
+			ClosureReason::DisconnectedPeer => f.write_str("the peer disconnected prior to the channel being funded"),
+			ClosureReason::OutdatedChannelManager => f.write_str("the ChannelManager read from disk was stale compared to ChannelMonitor(s)"),
+		}
+	}
+}
+
 impl_writeable_tlv_based_enum_upgradable!(ClosureReason,
 	(0, CounterpartyForceClosed) => { (1, peer_msg, required) },
 	(2, HolderForceClosed) => {},