Move pre-funded-channel immediate shutdown logic to the right place

Because a `Funded` `Channel` cannot possibly be pre-funding, the
logic in `ChannelManager::close_channel_internal` to handle
pre-funding channels is in the wrong place.

Rather than being handled inside the `Funded` branch, it should be
in an `else` following it, handling either of the two
`ChannelPhases` outside of `Funded`.

Sadly, because of a previous control flow management `loop {}`, the
existing code will infinite loop, which is fixed here.

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -2603,7 +2603,8 @@ where
 
 		let mut failed_htlcs: Vec<(HTLCSource, PaymentHash)>;
 		let mut shutdown_result = None;
-		loop {
+
+		{
 			let per_peer_state = self.per_peer_state.read().unwrap();
 
 			let peer_state_mutex = per_peer_state.get(counterparty_node_id)
@@ -2614,10 +2615,11 @@ where
 
 			match peer_state.channel_by_id.entry(channel_id.clone()) {
 				hash_map::Entry::Occupied(mut chan_phase_entry) => {
+					let unbroadcasted_batch_funding_txid =
+						chan_phase_entry.get().context().unbroadcasted_batch_funding_txid();
 					if let ChannelPhase::Funded(chan) = chan_phase_entry.get_mut() {
 						let funding_txo_opt = chan.context.get_funding_txo();
 						let their_features = &peer_state.latest_features;
-						let unbroadcasted_batch_funding_txid = chan.context.unbroadcasted_batch_funding_txid();
 						let (shutdown_msg, mut monitor_update_opt, htlcs) =
 							chan.get_shutdown(&self.signer_provider, their_features, target_feerate_sats_per_1000_weight, override_shutdown_script)?;
 						failed_htlcs = htlcs;
@@ -2637,21 +2639,12 @@ where
 						if let Some(monitor_update) = monitor_update_opt.take() {
 							handle_new_monitor_update!(self, funding_txo_opt.unwrap(), monitor_update,
 								peer_state_lock, peer_state, per_peer_state, chan);
-							break;
-						}
-
-						if chan.is_shutdown() {
-							if let ChannelPhase::Funded(chan) = remove_channel_phase!(self, chan_phase_entry) {
-								if let Ok(channel_update) = self.get_channel_update_for_broadcast(&chan) {
-									peer_state.pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
-										msg: channel_update
-									});
-								}
-								self.issue_channel_close_events(&chan.context, ClosureReason::HolderForceClosed);
-								shutdown_result = Some((None, Vec::new(), unbroadcasted_batch_funding_txid));
-							}
 						}
-						break;
+					} else {
+						self.issue_channel_close_events(chan_phase_entry.get().context(), ClosureReason::HolderForceClosed);
+						failed_htlcs = Vec::new();
+						remove_channel_phase!(self, chan_phase_entry);
+						shutdown_result = Some((None, Vec::new(), unbroadcasted_batch_funding_txid));
 					}
 				},
 				hash_map::Entry::Vacant(_) => {

lightning/src/ln/shutdown_tests.rs

@@ -275,6 +275,21 @@ fn shutdown_on_unfunded_channel() {
 	check_closed_event!(nodes[0], 1, ClosureReason::CounterpartyCoopClosedUnfundedChannel, [nodes[1].node.get_our_node_id()], 1_000_000);
 }
 
+#[test]
+fn close_on_unfunded_channel() {
+	// Test the user asking us to close prior to funding generation
+	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]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	let chan_id = nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 1_000_000, 100_000, 0, None).unwrap();
+	let open_chan = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
+
+	nodes[0].node.close_channel(&chan_id, &nodes[1].node.get_our_node_id()).unwrap();
+	check_closed_event!(nodes[0], 1, ClosureReason::HolderForceClosed, [nodes[1].node.get_our_node_id()], 1_000_000);
+}
+
 #[test]
 fn expect_channel_shutdown_state_with_force_closure() {
 	// Test sending a shutdown prior to channel_ready after funding generation