Fix GSO write

stack_mixed.go

@@ -13,7 +13,6 @@ import (
 	"github.com/sagernet/gvisor/pkg/tcpip/transport/udp"
 	"github.com/sagernet/gvisor/pkg/waiter"
 	"github.com/sagernet/sing-tun/internal/clashtcpip"
-	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/bufio"
 	"github.com/sagernet/sing/common/canceler"
 	E "github.com/sagernet/sing/common/exceptions"
@@ -95,7 +94,6 @@ func (m *Mixed) tunLoop() {
 		m.wintunLoop(winTun)
 		return
 	}
-
 	if batchTUN, isBatchTUN := m.tun.(BatchTUN); isBatchTUN {
 		batchSize := batchTUN.BatchSize()
 		if batchSize > 1 {
@@ -118,7 +116,12 @@ func (m *Mixed) tunLoop() {
 		}
 		rawPacket := packetBuffer[:frontHeadroom+n]
 		packet := packetBuffer[frontHeadroom+PacketOffset : frontHeadroom+n]
-		m.processPacket(rawPacket, packet)
+		if m.processPacket(packet) {
+			_, err = m.tun.Write(rawPacket)
+			if err != nil {
+				m.logger.Trace(E.Cause(err, "write packet"))
+			}
+		}
 	}
 }
 
@@ -132,7 +135,12 @@ func (m *Mixed) wintunLoop(winTun WinTun) {
 			release()
 			continue
 		}
-		m.processPacket(packet, packet)
+		if m.processPacket(packet) {
+			_, err = winTun.Write(packet)
+			if err != nil {
+				m.logger.Trace(E.Cause(err, "write packet"))
+			}
+		}
 		release()
 	}
 }
@@ -141,6 +149,7 @@ func (m *Mixed) batchLoop(linuxTUN BatchTUN, batchSize int) {
 	frontHeadroom := m.tun.FrontHeadroom()
 	packetBuffers := make([][]byte, batchSize)
 	readBuffers := make([][]byte, batchSize)
+	writeBuffers := make([][]byte, batchSize)
 	packetSizes := make([]int, batchSize)
 	for i := range packetBuffers {
 		packetBuffers[i] = make([]byte, m.mtu+frontHeadroom+PacketOffset)
@@ -163,69 +172,83 @@ func (m *Mixed) batchLoop(linuxTUN BatchTUN, batchSize int) {
 				continue
 			}
 			packetBuffer := packetBuffers[i]
-			rawPacket := packetBuffer[:frontHeadroom+packetSize]
 			packet := packetBuffer[frontHeadroom+PacketOffset : frontHeadroom+packetSize]
-			m.processPacket(rawPacket, packet)
+			if m.processPacket(packet) {
+				writeBuffers = append(writeBuffers, packetBuffer[:frontHeadroom+packetSize])
+			}
+		}
+		if len(writeBuffers) > 0 {
+			err = linuxTUN.BatchWrite(writeBuffers)
+			if err != nil {
+				m.logger.Trace(E.Cause(err, "batch write packet"))
+			}
+			writeBuffers = writeBuffers[:0]
 		}
 	}
 }
 
-func (m *Mixed) processPacket(rawPacket []byte, packet []byte) {
-	var err error
+func (m *Mixed) processPacket(packet []byte) bool {
+	var (
+		writeBack bool
+		err       error
+	)
 	switch ipVersion := packet[0] >> 4; ipVersion {
 	case 4:
-		err = m.processIPv4(rawPacket, packet)
+		writeBack, err = m.processIPv4(packet)
 	case 6:
-		err = m.processIPv6(rawPacket, packet)
+		writeBack, err = m.processIPv6(packet)
 	default:
 		err = E.New("ip: unknown version: ", ipVersion)
 	}
 	if err != nil {
 		m.logger.Trace(err)
+		return false
 	}
+	return writeBack
 }
 
-func (m *Mixed) processIPv4(rawPacket []byte, packet clashtcpip.IPv4Packet) error {
+func (m *Mixed) processIPv4(packet clashtcpip.IPv4Packet) (writeBack bool, err error) {
+	writeBack = true
 	destination := packet.DestinationIP()
 	if destination == m.broadcastAddr || !destination.IsGlobalUnicast() {
-		return common.Error(m.tun.Write(rawPacket))
+		return
 	}
 	switch packet.Protocol() {
 	case clashtcpip.TCP:
-		return m.processIPv4TCP(rawPacket, packet, packet.Payload())
+		err = m.processIPv4TCP(packet, packet.Payload())
 	case clashtcpip.UDP:
+		writeBack = false
 		pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
 			Payload: buffer.MakeWithData(packet),
 		})
 		m.endpoint.InjectInbound(header.IPv4ProtocolNumber, pkt)
 		pkt.DecRef()
-		return nil
+		return
 	case clashtcpip.ICMP:
-		return m.processIPv4ICMP(rawPacket, packet, packet.Payload())
-	default:
-		return common.Error(m.tun.Write(rawPacket))
+		err = m.processIPv4ICMP(packet, packet.Payload())
 	}
+	return
 }
 
-func (m *Mixed) processIPv6(rawPacket []byte, packet clashtcpip.IPv6Packet) error {
+func (m *Mixed) processIPv6(packet clashtcpip.IPv6Packet) (writeBack bool, err error) {
+	writeBack = true
 	if !packet.DestinationIP().IsGlobalUnicast() {
-		return common.Error(m.tun.Write(rawPacket))
+		return
 	}
 	switch packet.Protocol() {
 	case clashtcpip.TCP:
-		return m.processIPv6TCP(rawPacket, packet, packet.Payload())
+		err = m.processIPv6TCP(packet, packet.Payload())
 	case clashtcpip.UDP:
+		writeBack = false
 		pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
 			Payload: buffer.MakeWithData(packet),
 		})
 		m.endpoint.InjectInbound(header.IPv6ProtocolNumber, pkt)
 		pkt.DecRef()
-		return nil
 	case clashtcpip.ICMPv6:
-		return m.processIPv6ICMP(rawPacket, packet, packet.Payload())
-	default:
-		return common.Error(m.tun.Write(rawPacket))
+		err = m.processIPv6ICMP(packet, packet.Payload())
 	}
+	return
 }
 
 func (m *Mixed) packetLoop() {