Avoid unnecessarily alloc'ing a new buffer when decrypting messages

[rust-lightning] / lightning / src / ln / peer_handler.rs

diff --git a/lightning/src/ln/peer_handler.rs b/lightning/src/ln/peer_handler.rs
index ba3a733d225db072f70cc4d185ce4e4cfe1030e9..a1a4d4b26729c6822227b7d58f576ed0e1725ad1 100644 (file)
--- a/lightning/src/ln/peer_handler.rs
+++ b/lightning/src/ln/peer_handler.rs
@@ -27,7 +27,7 @@ use crate::ln::msgs::{ChannelMessageHandler, LightningError, SocketAddress, Onio
 #[cfg(not(c_bindings))]
 use crate::ln::channelmanager::{SimpleArcChannelManager, SimpleRefChannelManager};
 use crate::util::ser::{VecWriter, Writeable, Writer};
-use crate::ln::peer_channel_encryptor::{PeerChannelEncryptor,NextNoiseStep};
+use crate::ln::peer_channel_encryptor::{PeerChannelEncryptor, NextNoiseStep, MSG_BUF_ALLOC_SIZE};
 use crate::ln::wire;
 use crate::ln::wire::{Encode, Type};
 #[cfg(not(c_bindings))]
@@ -785,7 +785,7 @@ impl From<LightningError> for MessageHandlingError {
 
 macro_rules! encode_msg {
        ($msg: expr) => {{
-               let mut buffer = VecWriter(Vec::new());
+               let mut buffer = VecWriter(Vec::with_capacity(MSG_BUF_ALLOC_SIZE));
                wire::write($msg, &mut buffer).unwrap();
                buffer.0
        }}
@@ -1402,17 +1402,18 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
                                                                        }
                                                                        peer.pending_read_is_header = false;
                                                                } else {
-                                                                       let msg_data = try_potential_handleerror!(peer,
-                                                                               peer.channel_encryptor.decrypt_message(&peer.pending_read_buffer[..]));
-                                                                       assert!(msg_data.len() >= 2);
+                                                                       debug_assert!(peer.pending_read_buffer.len() >= 2 + 16);
+                                                                       try_potential_handleerror!(peer,
+                                                                               peer.channel_encryptor.decrypt_message(&mut peer.pending_read_buffer[..]));
+
+                                                                       let mut reader = io::Cursor::new(&peer.pending_read_buffer[..peer.pending_read_buffer.len() - 16]);
+                                                                       let message_result = wire::read(&mut reader, &*self.message_handler.custom_message_handler);
 
                                                                        // Reset read buffer
                                                                        if peer.pending_read_buffer.capacity() > 8192 { peer.pending_read_buffer = Vec::new(); }
                                                                        peer.pending_read_buffer.resize(18, 0);
                                                                        peer.pending_read_is_header = true;
 
-                                                                       let mut reader = io::Cursor::new(&msg_data[..]);
-                                                                       let message_result = wire::read(&mut reader, &*self.message_handler.custom_message_handler);
                                                                        let message = match message_result {
                                                                                Ok(x) => x,
                                                                                Err(e) => {