wintun: Read/write packet size from/to exchange buffer directly

Driver <-> user-space communication is local and using native endian.

Signed-off-by: Simon Rozman <simon@rozman.si>

diff --git a/tun/tun_windows.go b/tun/tun_windows.go
index 65c32f21569b831880f682ae71c263944a8c596a..e9bf0b77ff2e5374fd23f31ff7b8be8ac29c22d0 100644 (file)
--- a/tun/tun_windows.go
+++ b/tun/tun_windows.go
@@ -6,10 +6,10 @@
 package tun
 
 import (
-       "encoding/binary"
        "errors"
        "os"
        "sync"
+       "unsafe"
 
        "golang.org/x/sys/windows"
        "golang.zx2c4.com/wireguard/tun/wintun"
@@ -230,7 +230,7 @@ func (tun *nativeTun) Read(buff []byte, offset int) (int, error) {
                if tun.rdBuff.offset+packetExchangeAlignment <= tun.rdBuff.avail {
                        // Get packet from the exchange buffer.
                        packet := tun.rdBuff.data[tun.rdBuff.offset:]
-                       size := binary.LittleEndian.Uint32(packet[:4])
+                       size := *(*uint32)(unsafe.Pointer(&packet[0]))
                        pSize := packetAlign(packetExchangeAlignment + size)
                        if packetSizeMax < size || tun.rdBuff.avail < tun.rdBuff.offset+pSize {
                                // Invalid packet size.
@@ -332,7 +332,7 @@ func (tun *nativeTun) putTunPacket(buff []byte) error {
 
        // Write packet to the exchange buffer.
        packet := tun.wrBuff.data[tun.wrBuff.offset : tun.wrBuff.offset+pSize]
-       binary.LittleEndian.PutUint32(packet[:4], size)
+       *(*uint32)(unsafe.Pointer(&packet[0])) = size
        copy(packet[packetExchangeAlignment:packetExchangeAlignment+size], buff)
 
        tun.wrBuff.packetNum++