wintun: Adopt new packet data alignment

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

diff --git a/tun/tun_windows.go b/tun/tun_windows.go
index 5f9c0f445f9b52356728a6665d698ac9393cce81..838fdd1f2136f17ebde37dfc8b4ccd5d6cb103ee 100644 (file)
--- a/tun/tun_windows.go
+++ b/tun/tun_windows.go
@@ -16,11 +16,11 @@ import (
 )
 
 const (
-       packetSizeMax           uint32 = 0xeffc   // Maximum packet size: 4 + packetSizeMax == 0xf000
-       packetExchangeMax       uint32 = 256      // Number of packets that may be written at a time
-       packetExchangeAlignment uint32 = 16       // Number of bytes packets are aligned to in exchange buffers
-       packetExchangeSizeRead  uint32 = 0x100000 // Read exchange buffer size (defaults to 1MiB)
-       packetExchangeSizeWrite uint32 = 0x10000  // Write exchange buffer size (defaults to 64kiB)
+       packetExchangeMax       uint32 = 256                              // Number of packets that may be written at a time
+       packetExchangeAlignment uint32 = 16                               // Number of bytes packets are aligned to in exchange buffers
+       packetSizeMax           uint32 = 0xf000 - packetExchangeAlignment // Maximum packet size
+       packetExchangeSizeRead  uint32 = 0x100000                         // Read exchange buffer size (defaults to 1MiB)
+       packetExchangeSizeWrite uint32 = 0x10000                          // Write exchange buffer size (defaults to 64kiB)
 )
 
 type exchgBufRead struct {
@@ -228,10 +228,10 @@ func (tun *nativeTun) Read(buff []byte, offset int) (int, error) {
        }
 
        for {
-               if tun.rdBuff.offset+4 <= tun.rdBuff.avail {
+               if tun.rdBuff.offset+packetExchangeAlignment <= tun.rdBuff.avail {
                        // Get packet from the exchange buffer.
                        size := *(*uint32)(unsafe.Pointer(&tun.rdBuff.data[tun.rdBuff.offset]))
-                       pSize := packetAlign(4 + size)
+                       pSize := packetAlign(packetExchangeAlignment + size)
                        if packetSizeMax < size || tun.rdBuff.avail < tun.rdBuff.offset+pSize {
                                // Invalid packet size.
                                tun.rdBuff.avail = 0
@@ -239,7 +239,7 @@ func (tun *nativeTun) Read(buff []byte, offset int) (int, error) {
                        }
 
                        // Copy data.
-                       copy(buff[offset:], tun.rdBuff.data[tun.rdBuff.offset+4:][:size])
+                       copy(buff[offset:], tun.rdBuff.data[tun.rdBuff.offset+packetExchangeAlignment:][:size])
                        tun.rdBuff.offset += pSize
                        return int(size), nil
                }
@@ -319,7 +319,7 @@ func (tun *nativeTun) putTunPacket(buff []byte) error {
        if size > packetSizeMax {
                return errors.New("Packet too big")
        }
-       pSize := packetAlign(4 + size)
+       pSize := packetAlign(packetExchangeAlignment + size)
 
        if tun.wrBuff.packetNum >= packetExchangeMax || tun.wrBuff.offset+pSize >= packetExchangeSizeWrite {
                // Exchange buffer is full -> flush first.
@@ -331,7 +331,7 @@ func (tun *nativeTun) putTunPacket(buff []byte) error {
 
        // Write packet to the exchange buffer.
        *(*uint32)(unsafe.Pointer(&tun.wrBuff.data[tun.wrBuff.offset])) = size
-       copy(tun.wrBuff.data[tun.wrBuff.offset+4:][:size], buff)
+       copy(tun.wrBuff.data[tun.wrBuff.offset+packetExchangeAlignment:][:size], buff)
 
        tun.wrBuff.packetNum++
        tun.wrBuff.offset += pSize