add a ChannelUnavailable error

Author: yuntai

src/ln/channel.rs

@@ -2886,11 +2886,16 @@ impl Channel {
 			}
 		}
 		if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK != 0 {
-			return Err(APIError::APIMisuseError{err: "Shutdown already in progress"});
+			if (self.channel_state & ChannelState::LocalShutdownSent as u32) == ChannelState::LocalShutdownSent as u32 {
+				return Err(APIError::APIMisuseError{err: "Shutdown already in progress"});
+			}
+			else if (self.channel_state & ChannelState::RemoteShutdownSent as u32) == ChannelState::RemoteShutdownSent as u32 {
+				return Err(APIError::ChannelUnavailable{err: "Shutdown already in progress by remote"});
+			}
 		}
 		assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
 		if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-			return Err(APIError::APIMisuseError{err: "Cannot begin shutdown while peer is disconnected, maybe force-close instead?"});
+			return Err(APIError::ChannelUnavailable{err: "Cannot begin shutdown while peer is disconnected, maybe force-close instead?"});
 		}
 
 		let our_closing_script = self.get_closing_scriptpubkey();

src/ln/channelmanager.rs

@@ -481,7 +481,7 @@ impl ChannelManager {
 						(res, chan_entry.get().get_their_node_id(), Some(chan_entry.remove_entry().1))
 					} else { (res, chan_entry.get().get_their_node_id(), None) }
 				},
-				hash_map::Entry::Vacant(_) => return Err(APIError::APIMisuseError{err: "No such channel"})
+				hash_map::Entry::Vacant(_) => return Err(APIError::ChannelUnavailable{err: "No such channel"})
 			}
 		};
 		for htlc_source in res.1.drain(..) {

src/util/errors.rs

@@ -26,6 +26,14 @@ pub enum APIError {
 		/// A human-readable error message
 		err: &'static str
 	},
+
+
+	/// We were unable to complete the request since channel is disconnected or
+	/// shutdown in progress initiated by remote
+	ChannelUnavailable {
+		/// A human-readable error message
+		err: &'static str
+	}
 }
 
 impl fmt::Debug for APIError {
@@ -34,6 +42,7 @@ impl fmt::Debug for APIError {
 			APIError::APIMisuseError {ref err} => f.write_str(err),
 			APIError::FeeRateTooHigh {ref err, ref feerate} => write!(f, "{} feerate: {}", err, feerate),
 			APIError::RouteError {ref err} => f.write_str(err),
+			APIError::ChannelUnavailable {ref err} => f.write_str(err),
 		}
 	}
 }