fix fuzz test

Author: arik-so

lightning/src/ln/peer_handler.rs

@@ -537,13 +537,18 @@ impl<Descriptor: SocketDescriptor, CM: Deref> PeerManager<Descriptor, CM> where
 								}
 							}
 
-							let mut messages = conduit.decrypt_message_stream(Some(&peer.pending_read_buffer));
-
-							if messages.len() != 1 {
-								break; // the length should initially be one, though there will be a possibility of decrypting multiple messages at once in the future
+							let mut next_message_result = conduit.decrypt(&peer.pending_read_buffer);
+
+							let offset = next_message_result.1;
+							if offset == 0 {
+								// nothing got read
+								break;
+							}else{
+								peer.pending_read_buffer.drain(0..offset);
 							}
 
-							let msg_data = messages.remove(1);
+							// something got read, so we definitely have a message
+							let msg_data = next_message_result.0.unwrap();
 
 							let mut reader = ::std::io::Cursor::new(&msg_data[..]);
 							let message_result = wire::read(&mut reader);

lightning/src/ln/peers/conduit.rs

@@ -75,7 +75,7 @@ impl Conduit {
 	}
 
 	/// Decrypt a single message. Buffer is an undelimited amount of bytes
-	fn decrypt(&mut self, buffer: &[u8]) -> (Option<Vec<u8>>, usize) { // the response slice should have the same lifetime as the argument. It's the slice data is read from
+	pub(crate) fn decrypt(&mut self, buffer: &[u8]) -> (Option<Vec<u8>>, usize) { // the response slice should have the same lifetime as the argument. It's the slice data is read from
 		if buffer.len() < 18 {
 			return (None, 0);
 		}