Improve build tags

tun_darwin_gvisor.go

@@ -0,0 +1,138 @@
+//go:build !no_gvisor && darwin
+
+package tun
+
+import (
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/rw"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/bufferv2"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+var _ GVisorTun = (*NativeTun)(nil)
+
+func (t *NativeTun) NewEndpoint() (stack.LinkEndpoint, error) {
+	return &DarwinEndpoint{tun: t}, nil
+}
+
+var _ stack.LinkEndpoint = (*DarwinEndpoint)(nil)
+
+type DarwinEndpoint struct {
+	tun        *NativeTun
+	dispatcher stack.NetworkDispatcher
+}
+
+func (e *DarwinEndpoint) MTU() uint32 {
+	return e.tun.mtu
+}
+
+func (e *DarwinEndpoint) MaxHeaderLength() uint16 {
+	return 0
+}
+
+func (e *DarwinEndpoint) LinkAddress() tcpip.LinkAddress {
+	return ""
+}
+
+func (e *DarwinEndpoint) Capabilities() stack.LinkEndpointCapabilities {
+	return stack.CapabilityNone
+}
+
+func (e *DarwinEndpoint) Attach(dispatcher stack.NetworkDispatcher) {
+	if dispatcher == nil && e.dispatcher != nil {
+		e.dispatcher = nil
+		return
+	}
+	if dispatcher != nil && e.dispatcher == nil {
+		e.dispatcher = dispatcher
+		go e.dispatchLoop()
+	}
+}
+
+func (e *DarwinEndpoint) dispatchLoop() {
+	_buffer := buf.StackNewSize(int(e.tun.mtu) + 4)
+	defer common.KeepAlive(_buffer)
+	buffer := common.Dup(_buffer)
+	defer buffer.Release()
+	data := buffer.FreeBytes()
+	for {
+		n, err := e.tun.tunFile.Read(data)
+		if err != nil {
+			break
+		}
+		packet := data[4:n]
+		var networkProtocol tcpip.NetworkProtocolNumber
+		switch header.IPVersion(packet) {
+		case header.IPv4Version:
+			networkProtocol = header.IPv4ProtocolNumber
+			if header.IPv4(packet).DestinationAddress() == tcpip.Address(e.tun.inet4Address) {
+				e.tun.tunFile.Write(data[:n])
+				continue
+			}
+		case header.IPv6Version:
+			networkProtocol = header.IPv6ProtocolNumber
+			if header.IPv6(packet).DestinationAddress() == tcpip.Address(e.tun.inet6Address) {
+				e.tun.tunFile.Write(data[:n])
+				continue
+			}
+		default:
+			e.tun.tunFile.Write(data[:n])
+			continue
+		}
+		pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
+			Payload:           bufferv2.MakeWithData(data[4:n]),
+			IsForwardedPacket: true,
+		})
+		pkt.NetworkProtocolNumber = networkProtocol
+		dispatcher := e.dispatcher
+		if dispatcher == nil {
+			pkt.DecRef()
+			return
+		}
+		dispatcher.DeliverNetworkPacket(networkProtocol, pkt)
+		pkt.DecRef()
+	}
+}
+
+func (e *DarwinEndpoint) IsAttached() bool {
+	return e.dispatcher != nil
+}
+
+func (e *DarwinEndpoint) Wait() {
+}
+
+func (e *DarwinEndpoint) ARPHardwareType() header.ARPHardwareType {
+	return header.ARPHardwareNone
+}
+
+func (e *DarwinEndpoint) AddHeader(buffer *stack.PacketBuffer) {
+}
+
+var (
+	packetHeader4 = [4]byte{0x00, 0x00, 0x00, unix.AF_INET}
+	packetHeader6 = [4]byte{0x00, 0x00, 0x00, unix.AF_INET6}
+)
+
+func (e *DarwinEndpoint) WritePackets(packetBufferList stack.PacketBufferList) (int, tcpip.Error) {
+	var n int
+	for _, packet := range packetBufferList.AsSlice() {
+		var packetHeader []byte
+		switch packet.NetworkProtocolNumber {
+		case header.IPv4ProtocolNumber:
+			packetHeader = packetHeader4[:]
+		case header.IPv6ProtocolNumber:
+			packetHeader = packetHeader6[:]
+		}
+		_, err := rw.WriteV(e.tun.tunFd, append([][]byte{packetHeader}, packet.AsSlices()...))
+		if err != nil {
+			return n, &tcpip.ErrAborted{}
+		}
+		n++
+	}
+	return n, nil
+}