Add ping proxy support

stack_gvisor_icmp.go

@@ -0,0 +1,207 @@
+//go:build with_gvisor
+
+package tun
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/sagernet/gvisor/pkg/buffer"
+	"github.com/sagernet/gvisor/pkg/tcpip"
+	"github.com/sagernet/gvisor/pkg/tcpip/adapters/gonet"
+	"github.com/sagernet/gvisor/pkg/tcpip/header"
+	"github.com/sagernet/gvisor/pkg/tcpip/network/ipv4"
+	"github.com/sagernet/gvisor/pkg/tcpip/network/ipv6"
+	"github.com/sagernet/gvisor/pkg/tcpip/stack"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+type ICMPForwarder struct {
+	ctx       context.Context
+	stack     *stack.Stack
+	handler   Handler
+	directNat *RouteMapping
+}
+
+func NewICMPForwarder(ctx context.Context, stack *stack.Stack, handler Handler, timeout time.Duration) *ICMPForwarder {
+	return &ICMPForwarder{
+		ctx:       ctx,
+		stack:     stack,
+		handler:   handler,
+		directNat: NewRouteMapping(timeout),
+	}
+}
+
+func (f *ICMPForwarder) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketBuffer) bool {
+	if pkt.NetworkProtocolNumber == header.IPv4ProtocolNumber {
+		ipHdr := header.IPv4(pkt.NetworkHeader().Slice())
+		icmpHdr := header.ICMPv4(pkt.TransportHeader().Slice())
+		if icmpHdr.Type() != header.ICMPv4Echo || icmpHdr.Code() != 0 {
+			return false
+		}
+		sourceAddr := M.AddrFromIP(ipHdr.SourceAddressSlice())
+		destinationAddr := M.AddrFromIP(ipHdr.DestinationAddressSlice())
+		action, err := f.directNat.Lookup(DirectRouteSession{Source: sourceAddr, Destination: destinationAddr}, func() (DirectRouteDestination, error) {
+			return f.handler.PrepareConnection(
+				N.NetworkICMPv4,
+				M.SocksaddrFrom(sourceAddr, 0),
+				M.SocksaddrFrom(destinationAddr, 0),
+				&ICMPBackWriter{
+					stack:         f.stack,
+					packet:        pkt,
+					source:        ipHdr.SourceAddress(),
+					sourceNetwork: header.IPv4ProtocolNumber,
+				},
+			)
+		})
+		if err != nil {
+			return true
+		}
+		if action != nil {
+			// TODO: handle error
+			pkt.IncRef()
+			_ = action.WritePacketBuffer(pkt)
+			return true
+		}
+		icmpHdr.SetType(header.ICMPv4EchoReply)
+		sourceAddress := ipHdr.SourceAddress()
+		ipHdr.SetSourceAddress(ipHdr.DestinationAddress())
+		ipHdr.SetDestinationAddress(sourceAddress)
+		icmpHdr.SetChecksum(0)
+		icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr[:header.ICMPv4MinimumSize], pkt.Data().Checksum()))
+		ipHdr.SetChecksum(0)
+		ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
+		outgoingEP, gErr := f.stack.GetNetworkEndpoint(DefaultNIC, header.IPv4ProtocolNumber)
+		if gErr != nil {
+			// TODO: log error
+			return true
+		}
+		route, gErr := f.stack.FindRoute(
+			DefaultNIC,
+			id.LocalAddress,
+			id.RemoteAddress,
+			header.IPv6ProtocolNumber,
+			false,
+		)
+		if gErr != nil {
+			// TODO: log error
+			return true
+		}
+		defer route.Release()
+		outgoingEP.(ipv4.ExportedEndpoint).WritePacketDirect(route, pkt)
+		return true
+	} else {
+		ipHdr := header.IPv6(pkt.NetworkHeader().Slice())
+		icmpHdr := header.ICMPv6(pkt.TransportHeader().Slice())
+		if icmpHdr.Type() != header.ICMPv6EchoRequest || icmpHdr.Code() != 0 {
+			return false
+		}
+		sourceAddr := M.AddrFromIP(ipHdr.SourceAddressSlice())
+		destinationAddr := M.AddrFromIP(ipHdr.DestinationAddressSlice())
+		action, err := f.directNat.Lookup(DirectRouteSession{Source: sourceAddr, Destination: destinationAddr}, func() (DirectRouteDestination, error) {
+			return f.handler.PrepareConnection(
+				N.NetworkICMPv6,
+				M.SocksaddrFrom(sourceAddr, 0),
+				M.SocksaddrFrom(destinationAddr, 0),
+				&ICMPBackWriter{
+					stack:         f.stack,
+					packet:        pkt,
+					source:        ipHdr.SourceAddress(),
+					sourceNetwork: header.IPv6ProtocolNumber,
+				},
+			)
+		})
+		if err != nil {
+			return true
+		}
+		if action != nil {
+			// TODO: handle error
+			pkt.IncRef()
+			_ = action.WritePacketBuffer(pkt)
+			return true
+		}
+		icmpHdr.SetType(header.ICMPv6EchoReply)
+		sourceAddress := ipHdr.SourceAddress()
+		ipHdr.SetSourceAddress(ipHdr.DestinationAddress())
+		ipHdr.SetDestinationAddress(sourceAddress)
+		icmpHdr.SetChecksum(header.ICMPv6Checksum(header.ICMPv6ChecksumParams{
+			Header: icmpHdr,
+			Src:    ipHdr.SourceAddress(),
+			Dst:    ipHdr.DestinationAddress(),
+		}))
+		outgoingEP, gErr := f.stack.GetNetworkEndpoint(DefaultNIC, header.IPv4ProtocolNumber)
+		if gErr != nil {
+			// TODO: log error
+			return true
+		}
+		route, gErr := f.stack.FindRoute(
+			DefaultNIC,
+			id.LocalAddress,
+			id.RemoteAddress,
+			header.IPv6ProtocolNumber,
+			false,
+		)
+		if gErr != nil {
+			// TODO: log error
+			return true
+		}
+		defer route.Release()
+		outgoingEP.(ipv6.ExportedEndpoint).WritePacketDirect(route, pkt)
+		return true
+	}
+}
+
+type ICMPBackWriter struct {
+	access        sync.Mutex
+	stack         *stack.Stack
+	packet        *stack.PacketBuffer
+	source        tcpip.Address
+	sourceNetwork tcpip.NetworkProtocolNumber
+}
+
+func (w *ICMPBackWriter) WritePacket(p []byte) error {
+	if w.sourceNetwork == header.IPv4ProtocolNumber {
+		route, err := w.stack.FindRoute(
+			DefaultNIC,
+			header.IPv4(p).SourceAddress(),
+			w.source,
+			w.sourceNetwork,
+			false,
+		)
+		if err != nil {
+			return gonet.TranslateNetstackError(err)
+		}
+		defer route.Release()
+		packet := stack.NewPacketBuffer(stack.PacketBufferOptions{
+			Payload: buffer.MakeWithData(p),
+		})
+		defer packet.DecRef()
+		err = route.WriteHeaderIncludedPacket(packet)
+		if err != nil {
+			return gonet.TranslateNetstackError(err)
+		}
+	} else {
+		route, err := w.stack.FindRoute(
+			DefaultNIC,
+			header.IPv6(p).SourceAddress(),
+			w.source,
+			w.sourceNetwork,
+			false,
+		)
+		if err != nil {
+			return gonet.TranslateNetstackError(err)
+		}
+		defer route.Release()
+		packet := stack.NewPacketBuffer(stack.PacketBufferOptions{
+			Payload: buffer.MakeWithData(p),
+		})
+		defer packet.DecRef()
+		err = route.WriteHeaderIncludedPacket(packet)
+		if err != nil {
+			return gonet.TranslateNetstackError(err)
+		}
+	}
+	return nil
+}