Add new DecodeError for messages that include zlib-compressed values

No need to disconnect peers if this error is encountered. It just means
we can't use some of their gossip messages.

Author: valentinewallace

fuzz/src/router.rs

@@ -133,6 +133,7 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 					msgs::DecodeError::BadLengthDescriptor => return,
 					msgs::DecodeError::ShortRead => panic!("We picked the length..."),
 					msgs::DecodeError::Io(e) => panic!("{:?}", e),
+					msgs::DecodeError::UnsupportedCompression => return,
 				}
 			}
 		}}

lightning/src/ln/msgs.rs

@@ -63,6 +63,8 @@ pub enum DecodeError {
 	/// Error from std::io
 	Io(/// (C-not exported) as ErrorKind doesn't have a reasonable mapping
         ::std::io::ErrorKind),
+	/// The message included zlib-compressed values, which we don't support.
+	UnsupportedCompression,
 }
 
 /// An init message to be sent or received from a peer
@@ -953,6 +955,7 @@ impl fmt::Display for DecodeError {
 			DecodeError::ShortRead => f.write_str("Packet extended beyond the provided bytes"),
 			DecodeError::BadLengthDescriptor => f.write_str("A length descriptor in the packet didn't describe the later data correctly"),
 			DecodeError::Io(ref e) => e.fmt(f),
+			DecodeError::UnsupportedCompression => f.write_str("We don't support receiving messages with zlib-compressed fields"),
 		}
 	}
 }

lightning/src/ln/peer_handler.rs

@@ -783,6 +783,10 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref> PeerManager<D
 													}
 													msgs::DecodeError::BadLengthDescriptor => return Err(PeerHandleError { no_connection_possible: false }),
 													msgs::DecodeError::Io(_) => return Err(PeerHandleError { no_connection_possible: false }),
+													msgs::DecodeError::UnsupportedCompression => {
+														log_debug!(self.logger, "We don't support zlib-compressed message fields, ignoring message");
+														continue;
+													}
 												}
 											}
 										};