Introduce new code changes properly handling this new behavior

- Do not remove channel immediately when peer_disconnect, instead
  removed it after some time if peer doesn't reconnect soon (handled in
previous commit).
- Do not mark per ok_to_remove if we have some OutboundV1Channels too.
- Rebroadcast SendOpenChannel for outboundV1Channel when peer
  reconnects.
- Also, update the relevant tests to account for the new behavior change

Author: shaavan

lightning/src/ln/channelmanager.rs

@@ -874,6 +874,7 @@ impl <SP: Deref> PeerState<SP> where SP::Target: SignerProvider {
 			return false
 		}
 		self.channel_by_id.iter().filter(|(_, phase)| matches!(phase, ChannelPhase::Funded(_))).count() == 0
+			&& self.channel_by_id.iter().filter(|(_, phase)| matches!(phase, ChannelPhase::UnfundedOutboundV1(_))).count() == 0
 			&& self.monitor_update_blocked_actions.is_empty()
 			&& self.in_flight_monitor_updates.is_empty()
 	}
@@ -8734,10 +8735,12 @@ where
 							}
 							&mut chan.context
 						},
-						// Unfunded channels will always be removed.
-						ChannelPhase::UnfundedOutboundV1(chan) => {
-							&mut chan.context
+						// We retain UnfundedOutboundV1 channel for some time in case
+						// peer unexpectedly disconnects, and intends to reconnect again.
+						ChannelPhase::UnfundedOutboundV1(_) => {
+							return true;
 						},
+						// Unfunded inbound channels will always be removed.
 						ChannelPhase::UnfundedInboundV1(chan) => {
 							&mut chan.context
 						},
@@ -8877,21 +8880,27 @@ where
 				let peer_state = &mut *peer_state_lock;
 				let pending_msg_events = &mut peer_state.pending_msg_events;
 
-				peer_state.channel_by_id.iter_mut().filter_map(|(_, phase)|
-					if let ChannelPhase::Funded(chan) = phase { Some(chan) } else {
-						// Since unfunded channel maps are cleared upon disconnecting a peer, and they're not persisted
-						// (so won't be recovered after a crash), they shouldn't exist here and we would never need to
-						// worry about closing and removing them.
+				for (_, phase) in peer_state.channel_by_id.iter_mut() {
+					if let ChannelPhase::Funded(chan) = phase {
+						let logger = WithChannelContext::from(&self.logger, &chan.context);
+						pending_msg_events.push(events::MessageSendEvent::SendChannelReestablish {
+							node_id: chan.context.get_counterparty_node_id(),
+							msg: chan.get_channel_reestablish(&&logger),
+						});
+					}
+					else if let ChannelPhase::UnfundedOutboundV1(chan) = phase {
+						pending_msg_events.push(events::MessageSendEvent::SendOpenChannel {
+							node_id: chan.context.get_counterparty_node_id(),
+							msg: chan.get_open_channel(self.chain_hash),
+						});
+					}
+					else {
+						// Since unfunded inbound channel maps are cleared upon disconnecting a peer, and they're not
+						// persisted (so won't be recovered after a crash), they shouldn't exist here and we would never
+						// need to worry about closing and removing them.
 						debug_assert!(false);
-						None
 					}
-				).for_each(|chan| {
-					let logger = WithChannelContext::from(&self.logger, &chan.context);
-					pending_msg_events.push(events::MessageSendEvent::SendChannelReestablish {
-						node_id: chan.context.get_counterparty_node_id(),
-						msg: chan.get_channel_reestablish(&&logger),
-					});
-				});
+				}
 			}
 
 			return NotifyOption::SkipPersistHandleEvents;

lightning/src/ln/functional_tests.rs

@@ -3692,7 +3692,7 @@ fn test_dup_events_on_peer_disconnect() {
 #[test]
 fn test_peer_disconnected_before_funding_broadcasted() {
 	// Test that channels are closed with `ClosureReason::DisconnectedPeer` if the peer disconnects
-	// before the funding transaction has been broadcasted.
+	// before the funding transaction has been broadcasted, and doesn't reconnect back within time.
 	let chanmon_cfgs = create_chanmon_cfgs(2);
 	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
 	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
@@ -3721,11 +3721,15 @@ fn test_peer_disconnected_before_funding_broadcasted() {
 		assert_eq!(nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().len(), 0);
 	}
 
-	// Ensure that the channel is closed with `ClosureReason::DisconnectedPeer` when the peers are
-	// disconnected before the funding transaction was broadcasted.
+	// Ensure that the channel is closed after timeout with `ClosureReason::DisconnectedPeer`
+	// when the peers are disconnected before the funding transaction was broadcasted.
 	nodes[0].node.peer_disconnected(&nodes[1].node.get_our_node_id());
 	nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id());
 
+	// The timer ticks while waiting for peer to connect back
+	nodes[0].node.timer_tick_occurred();
+	nodes[0].node.timer_tick_occurred();
+
 	check_closed_event!(&nodes[0], 2, ClosureReason::DisconnectedPeer, true
 		, [nodes[1].node.get_our_node_id()], 1000000);
 	check_closed_event!(&nodes[1], 1, ClosureReason::DisconnectedPeer, false
@@ -10526,6 +10530,10 @@ fn test_disconnect_in_funding_batch() {
 	// The remaining peer in the batch disconnects.
 	nodes[0].node.peer_disconnected(&nodes[2].node.get_our_node_id());
 
+	// After the time expires for allowing peer to connect back
+	nodes[0].node.timer_tick_occurred();
+	nodes[0].node.timer_tick_occurred();
+
 	// The channels in the batch will close immediately.
 	let channel_id_1 = OutPoint { txid: tx.txid(), index: 0 }.to_channel_id();
 	let channel_id_2 = OutPoint { txid: tx.txid(), index: 1 }.to_channel_id();