Fix inbound zero-conf

When we receive an inbound zero-conf channel, we need to defer sending the
`channel_ready` message until *after* we've sent the `funding_signed`
message. We won't be able to produce the `funding_signed` message until the
signer has produced the counterparty commitment signature.

Author: waterson

lightning/src/ln/async_signer_tests.rs

@@ -10,7 +10,7 @@
 //! Tests for asynchronous signing. These tests verify that the channel state machine behaves
 //! properly with a signer implementation that asynchronously derives signatures.
 
-use crate::events::{MessageSendEvent, MessageSendEventsProvider};
+use crate::events::{Event, MessageSendEvent, MessageSendEventsProvider};
 use crate::ln::functional_test_utils::*;
 use crate::ln::msgs::ChannelMessageHandler;
 use crate::ln::channelmanager::{PaymentId, RecipientOnionFields};
@@ -189,6 +189,112 @@ fn test_async_commitment_signature_for_commitment_signed() {
 	};
 }
 
+#[test]
+fn test_async_commitment_signature_for_funding_signed_0conf() {
+	// Simulate acquiring the signature for `funding_signed` asynchronously for a zero-conf channel.
+	let mut manually_accept_config = test_default_channel_config();
+	manually_accept_config.manually_accept_inbound_channels = true;
+
+	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, Some(manually_accept_config)]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	// nodes[0] --- open_channel --> nodes[1]
+	nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100000, 10001, 42, None).unwrap();
+	let open_channel = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
+
+	nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), &open_channel);
+
+	{
+		let events = nodes[1].node.get_and_clear_pending_events();
+		assert_eq!(events.len(), 1, "Expected one event, got {}", events.len());
+		match &events[0] {
+			Event::OpenChannelRequest { temporary_channel_id, .. } => {
+				nodes[1].node.accept_inbound_channel_from_trusted_peer_0conf(
+					temporary_channel_id, &nodes[0].node.get_our_node_id(), 0)
+					.expect("Unable to accept inbound zero-conf channel");
+			},
+			ev => panic!("Expected OpenChannelRequest, not {:?}", ev)
+		}
+	}
+
+	// nodes[0] <-- accept_channel --- nodes[1]
+	let accept_channel = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
+	assert_eq!(accept_channel.minimum_depth, 0, "Expected minimum depth of 0");
+	nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), &accept_channel);
+
+	// nodes[0] --- funding_created --> nodes[1]
+	let (temporary_channel_id, tx, _) = create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 100000, 42);
+	nodes[0].node.funding_transaction_generated(&temporary_channel_id, &nodes[1].node.get_our_node_id(), tx.clone()).unwrap();
+	check_added_monitors(&nodes[0], 0);
+
+	let mut funding_created_msg = get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());
+
+	// Now let's make node[1]'s signer be unavailable while handling the `funding_created`. It should
+	// *not* broadcast a `funding_signed`...
+	nodes[1].set_channel_signer_available(&nodes[0].node.get_our_node_id(), &temporary_channel_id, false);
+	nodes[1].node.handle_funding_created(&nodes[0].node.get_our_node_id(), &funding_created_msg);
+	check_added_monitors(&nodes[1], 1);
+
+	{
+		let events = nodes[1].node.get_and_clear_pending_msg_events();
+		let n = events.len();
+		assert_eq!(n, 0, "expected no events generated from nodes[1], found {}", n);
+	}
+
+	// Now re-enable the signer and simulate a retry. The temporary_channel_id won't work anymore so
+	// we have to dig out the real channel ID.
+	let chan_id = {
+		let per_peer_state = nodes[1].node.per_peer_state.read().unwrap();
+		let chan_lock = per_peer_state.get(&nodes[0].node.get_our_node_id()).unwrap().lock().unwrap();
+		let chan_ids = chan_lock.channel_by_id.keys().collect::<Vec<_>>();
+		let n = chan_ids.len();
+		assert_eq!(n, 1, "expected one channel, not {}", n);
+		*chan_ids[0]
+	};
+
+	// At this point, we basically expect the channel to open like a normal zero-conf channel.
+	nodes[1].set_channel_signer_available(&nodes[0].node.get_our_node_id(), &chan_id, true);
+	nodes[1].node.signer_unblocked(Some((nodes[0].node.get_our_node_id(), chan_id)));
+
+	let (funding_signed, channel_ready_1) = {
+		let events = nodes[1].node.get_and_clear_pending_msg_events();
+		assert_eq!(events.len(), 2);
+		let funding_signed = match &events[0] {
+			MessageSendEvent::SendFundingSigned { msg, .. } => msg.clone(),
+			ev => panic!("Expected SendFundingSigned, not {:?}", ev)
+		};
+		let channel_ready = match &events[1] {
+			MessageSendEvent::SendChannelReady { msg, .. } => msg.clone(),
+			ev => panic!("Expected SendChannelReady, not {:?}", ev)
+		};
+		(funding_signed, channel_ready)
+	};
+
+	nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed);
+	expect_channel_pending_event(&nodes[0], &nodes[1].node.get_our_node_id());
+	expect_channel_pending_event(&nodes[1], &nodes[0].node.get_our_node_id());
+	check_added_monitors(&nodes[0], 1);
+
+	let channel_ready_0 = get_event_msg!(nodes[0], MessageSendEvent::SendChannelReady, nodes[1].node.get_our_node_id());
+
+	nodes[0].node.handle_channel_ready(&nodes[1].node.get_our_node_id(), &channel_ready_1);
+	expect_channel_ready_event(&nodes[0], &nodes[1].node.get_our_node_id());
+
+	nodes[1].node.handle_channel_ready(&nodes[0].node.get_our_node_id(), &channel_ready_0);
+	expect_channel_ready_event(&nodes[1], &nodes[0].node.get_our_node_id());
+
+	let channel_update_0 = get_event_msg!(nodes[0], MessageSendEvent::SendChannelUpdate, nodes[1].node.get_our_node_id());
+	let channel_update_1 = get_event_msg!(nodes[1], MessageSendEvent::SendChannelUpdate, nodes[0].node.get_our_node_id());
+
+	nodes[0].node.handle_channel_update(&nodes[1].node.get_our_node_id(), &channel_update_1);
+	nodes[1].node.handle_channel_update(&nodes[0].node.get_our_node_id(), &channel_update_0);
+
+	assert_eq!(nodes[0].node.list_usable_channels().len(), 1);
+	assert_eq!(nodes[1].node.list_usable_channels().len(), 1);
+}
+
 #[test]
 fn test_async_commitment_signature_for_peer_disconnect() {
 	let chanmon_cfgs = create_chanmon_cfgs(2);

lightning/src/ln/channel.rs

@@ -520,6 +520,7 @@ pub(super) struct SignerResumeUpdates {
 	pub commitment_update: Option<msgs::CommitmentUpdate>,
 	pub funding_signed: Option<msgs::FundingSigned>,
 	pub funding_created: Option<msgs::FundingCreated>,
+	pub channel_ready: Option<msgs::ChannelReady>,
 }
 
 /// The return value of `channel_reestablish`
@@ -3892,13 +3893,17 @@ impl<SP: Deref> Channel<SP> where
 		let funding_signed = if self.context.signer_pending_funding && !self.context.is_outbound() {
 			self.context.get_funding_signed_msg(logger).1
 		} else { None };
+		let channel_ready = if funding_signed.is_some() {
+			self.check_get_channel_ready(0)
+		} else { None };
 		let funding_created = if self.context.signer_pending_funding && self.context.is_outbound() {
 			self.context.get_funding_created_msg(logger)
 		} else { None };
 		SignerResumeUpdates {
 			commitment_update,
 			funding_signed,
 			funding_created,
+			channel_ready,
 		}
 	}
 
@@ -6706,15 +6711,16 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 			counterparty_initial_commitment_tx.to_broadcaster_value_sat(),
 			counterparty_initial_commitment_tx.to_countersignatory_value_sat(), logger);
 
-		log_info!(logger, "Generated funding_signed for peer for channel {}", &self.context.channel_id());
+		log_info!(logger, "{} funding_signed for peer for channel {}",
+			if funding_signed.is_some() { "Generated" } else { "Waiting for signature on" }, &self.context.channel_id());
 
 		// Promote the channel to a full-fledged one now that we have updated the state and have a
 		// `ChannelMonitor`.
 		let mut channel = Channel {
 			context: self.context,
 		};
 
-		let need_channel_ready = channel.check_get_channel_ready(0).is_some();
+		let need_channel_ready = funding_signed.is_some() && channel.check_get_channel_ready(0).is_some();
 		channel.monitor_updating_paused(false, false, need_channel_ready, Vec::new(), Vec::new(), Vec::new());
 
 		Ok((channel, funding_signed, channel_monitor))

lightning/src/ln/channelmanager.rs

@@ -6800,9 +6800,9 @@ where
 		let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
 
 		let unblock_chan = |phase: &mut ChannelPhase<SP>, pending_msg_events: &mut Vec<MessageSendEvent>| {
+			let node_id = phase.context().get_counterparty_node_id();
 			if let ChannelPhase::Funded(chan) = phase {
 				let msgs = chan.signer_maybe_unblocked(&self.logger);
-				let node_id = phase.context().get_counterparty_node_id();
 				if let Some(updates) = msgs.commitment_update {
 					pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
 						node_id,
@@ -6821,6 +6821,9 @@ where
 						msg,
 					});
 				}
+				if let Some(msg) = msgs.channel_ready {
+					send_channel_ready!(self, pending_msg_events, chan, msg);
+				}
 			}
 		};