Remove redundant check, add comment, fix indentation, small refactor

Author: valentinewallace

lightning/src/ln/channel.rs

@@ -1736,14 +1736,6 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
   pub fn update_add_htlc<F>(&mut self, msg: &msgs::UpdateAddHTLC, mut pending_forward_state: PendingHTLCStatus, create_pending_htlc_status: F) -> Result<(), ChannelError>
   where F: for<'a> Fn(&'a Self, PendingHTLCStatus, u16) -> PendingHTLCStatus {
 		if !self.is_usable() {
-			// TODO: Note that |20 is defined as "channel FROM the processing
-			// node has been disabled" (emphasis mine), which seems to imply
-			// that we can't return |20 for an inbound channel being disabled.
-			// This probably needs a spec update but should definitely be
-			// allowed.
-			pending_forward_state = create_pending_htlc_status(self, pending_forward_state, 0x1000|20);
-		}
-		if (self.channel_state & (ChannelState::ChannelFunded as u32 | ChannelState::RemoteShutdownSent as u32)) != (ChannelState::ChannelFunded as u32) {
 			return Err(ChannelError::Close("Got add HTLC message when channel was not in an operational state"));
 		}
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
@@ -1815,6 +1807,8 @@ impl<ChanSigner: ChannelKeys> Channel<ChanSigner> {
 			// but should help protect us from stuck channels).
 			let remote_fee_cost_incl_stuck_buffer_msat = 2 * self.next_remote_commit_tx_fee_msat(1 + 1);
 			if pending_remote_value_msat - msg.amount_msat - chan_reserve_msat < remote_fee_cost_incl_stuck_buffer_msat {
+				// Note that if we get None here, it's because we're already failing the HTLC, i.e. its
+				// status is already set to failing.
 				pending_forward_state = create_pending_htlc_status(self, pending_forward_state, 0x1000|7);
 			}
 		} else {

lightning/src/ln/channelmanager.rs

@@ -2510,21 +2510,22 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 					// want to reject the new HTLC and fail it backwards instead of forwarding.
 					match pending_forward_info {
 						PendingHTLCStatus::Forward(PendingHTLCInfo { ref incoming_shared_secret, .. }) => {
-							let mut reason = onion_utils::build_first_hop_failure_packet(incoming_shared_secret, 0x4000|10, &[]);
 							// The only case where we'd be unable to successfully get a channel
 							// update here is if the channel isn't in the fully-funded
 							// state yet, implying our counterparty is trying to route payments
 							// over the channel back to themselves (cause no one else should
 							// know the short_id is a lightning channel yet). We should have no
 							// problem just calling this unknown_next_peer, as above (0x4000|10).
-							if let Ok(upd) = self.get_channel_update(chan) {
-								reason = onion_utils::build_first_hop_failure_packet(incoming_shared_secret, error_code, &{
+							let reason = if let Ok(upd) = self.get_channel_update(chan) {
+								onion_utils::build_first_hop_failure_packet(incoming_shared_secret, error_code, &{
 									let mut res = Vec::with_capacity(8 + 128);
 									res.extend_from_slice(&byte_utils::be16_to_array(upd.contents.flags));
 									res.extend_from_slice(&upd.encode_with_len()[..]);
 									res
-								}[..]);
-							}
+								}[..])
+							} else {
+								onion_utils::build_first_hop_failure_packet(incoming_shared_secret, 0x4000|10, &[])
+							};
 							let msg = msgs::UpdateFailHTLC {
 								channel_id: msg.channel_id,
 								htlc_id: msg.htlc_id,
@@ -2535,7 +2536,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 						_ => pending_forward_info
 					}
 				};
-        try_chan_entry!(self, chan.get_mut().update_add_htlc(&msg, pending_forward_info, create_pending_htlc_status), channel_state, chan);
+				try_chan_entry!(self, chan.get_mut().update_add_htlc(&msg, pending_forward_info, create_pending_htlc_status), channel_state, chan);
 			},
 			hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel", msg.channel_id))
 		}