Fix reachable unwrap on non-channel_type manual channel acceptance

If we receive an `OpenChannel` message without a `channel_type`
with `manually_accept_inbound_channels` set, we will `unwrap()`
`None`.

This is uncommon these days as most nodes support `channel_type`,
but sadly is rather trivial for a peer to hit for those with manual
channel acceptance enabled.

Reported in and fixes #2804. Luckily, the updated
`full_stack_target` has no issue reaching this issue quickly.

Author: TheBlueMatt

lightning/src/ln/channel.rs

@@ -6845,6 +6845,41 @@ pub(super) struct InboundV1Channel<SP: Deref> where SP::Target: SignerProvider {
 	pub unfunded_context: UnfundedChannelContext,
 }
 
+/// Fetches the [`ChannelTypeFeatures`] that will be used for a channel built from a given
+/// [`msgs::OpenChannel`].
+pub(super) fn channel_type_from_open_channel(
+	msg: &msgs::OpenChannel, their_features: &InitFeatures,
+	our_supported_features: &ChannelTypeFeatures
+) -> Result<ChannelTypeFeatures, ChannelError> {
+	if let Some(channel_type) = &msg.channel_type {
+		if channel_type.supports_any_optional_bits() {
+			return Err(ChannelError::Close("Channel Type field contained optional bits - this is not allowed".to_owned()));
+		}
+
+		// We only support the channel types defined by the `ChannelManager` in
+		// `provided_channel_type_features`. The channel type must always support
+		// `static_remote_key`.
+		if !channel_type.requires_static_remote_key() {
+			return Err(ChannelError::Close("Channel Type was not understood - we require static remote key".to_owned()));
+		}
+		// Make sure we support all of the features behind the channel type.
+		if !channel_type.is_subset(our_supported_features) {
+			return Err(ChannelError::Close("Channel Type contains unsupported features".to_owned()));
+		}
+		let announced_channel = if (msg.channel_flags & 1) == 1 { true } else { false };
+		if channel_type.requires_scid_privacy() && announced_channel {
+			return Err(ChannelError::Close("SCID Alias/Privacy Channel Type cannot be set on a public channel".to_owned()));
+		}
+		Ok(channel_type.clone())
+	} else {
+		let channel_type = ChannelTypeFeatures::from_init(&their_features);
+		if channel_type != ChannelTypeFeatures::only_static_remote_key() {
+			return Err(ChannelError::Close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
+		}
+		Ok(channel_type)
+	}
+}
+
 impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 	/// Creates a new channel from a remote sides' request for one.
 	/// Assumes chain_hash has already been checked and corresponds with what we expect!
@@ -6863,32 +6898,7 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
 
 		// First check the channel type is known, failing before we do anything else if we don't
 		// support this channel type.
-		let channel_type = if let Some(channel_type) = &msg.channel_type {
-			if channel_type.supports_any_optional_bits() {
-				return Err(ChannelError::Close("Channel Type field contained optional bits - this is not allowed".to_owned()));
-			}
-
-			// We only support the channel types defined by the `ChannelManager` in
-			// `provided_channel_type_features`. The channel type must always support
-			// `static_remote_key`.
-			if !channel_type.requires_static_remote_key() {
-				return Err(ChannelError::Close("Channel Type was not understood - we require static remote key".to_owned()));
-			}
-			// Make sure we support all of the features behind the channel type.
-			if !channel_type.is_subset(our_supported_features) {
-				return Err(ChannelError::Close("Channel Type contains unsupported features".to_owned()));
-			}
-			if channel_type.requires_scid_privacy() && announced_channel {
-				return Err(ChannelError::Close("SCID Alias/Privacy Channel Type cannot be set on a public channel".to_owned()));
-			}
-			channel_type.clone()
-		} else {
-			let channel_type = ChannelTypeFeatures::from_init(&their_features);
-			if channel_type != ChannelTypeFeatures::only_static_remote_key() {
-				return Err(ChannelError::Close("Only static_remote_key is supported for non-negotiated channel types".to_owned()));
-			}
-			channel_type
-		};
+		let channel_type = channel_type_from_open_channel(msg, their_features, our_supported_features)?;
 
 		let channel_keys_id = signer_provider.generate_channel_keys_id(true, msg.funding_satoshis, user_id);
 		let holder_signer = signer_provider.derive_channel_signer(msg.funding_satoshis, channel_keys_id);

lightning/src/ln/channelmanager.rs

@@ -43,7 +43,7 @@ use crate::events::{Event, EventHandler, EventsProvider, MessageSendEvent, Messa
 // Since this struct is returned in `list_channels` methods, expose it here in case users want to
 // construct one themselves.
 use crate::ln::{inbound_payment, ChannelId, PaymentHash, PaymentPreimage, PaymentSecret};
-use crate::ln::channel::{Channel, ChannelPhase, ChannelContext, ChannelError, ChannelUpdateStatus, ShutdownResult, UnfundedChannelContext, UpdateFulfillCommitFetch, OutboundV1Channel, InboundV1Channel, WithChannelContext};
+use crate::ln::channel::{self, Channel, ChannelPhase, ChannelContext, ChannelError, ChannelUpdateStatus, ShutdownResult, UnfundedChannelContext, UpdateFulfillCommitFetch, OutboundV1Channel, InboundV1Channel, WithChannelContext};
 use crate::ln::features::{Bolt12InvoiceFeatures, ChannelFeatures, ChannelTypeFeatures, InitFeatures, NodeFeatures};
 #[cfg(any(feature = "_test_utils", test))]
 use crate::ln::features::Bolt11InvoiceFeatures;
@@ -6170,13 +6170,21 @@ where
 
 		// If we're doing manual acceptance checks on the channel, then defer creation until we're sure we want to accept.
 		if self.default_configuration.manually_accept_inbound_channels {
+			let channel_type_res = channel::channel_type_from_open_channel(
+				&msg, &peer_state.latest_features, &self.channel_type_features()
+			);
+			let channel_type = match channel_type_res {
+				Ok(channel_type) => channel_type,
+				Err(e) =>
+					return Err(MsgHandleErrInternal::from_chan_no_close(e, msg.temporary_channel_id)),
+			};
 			let mut pending_events = self.pending_events.lock().unwrap();
 			pending_events.push_back((events::Event::OpenChannelRequest {
 				temporary_channel_id: msg.temporary_channel_id.clone(),
 				counterparty_node_id: counterparty_node_id.clone(),
 				funding_satoshis: msg.funding_satoshis,
 				push_msat: msg.push_msat,
-				channel_type: msg.channel_type.clone().unwrap(),
+				channel_type,
 			}, None));
 			peer_state.inbound_channel_request_by_id.insert(channel_id, InboundChannelRequest {
 				open_channel_msg: msg.clone(),