ping: Add gVisor destination

ping/destination_gvisor.go

@@ -0,0 +1,113 @@
+//go:build with_gvisor
+
+package ping
+
+import (
+	"context"
+	"net/netip"
+
+	"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/stack"
+	"github.com/sagernet/gvisor/pkg/waiter"
+	"github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/logger"
+)
+
+var _ tun.DirectRouteDestination = (*GVisorDestination)(nil)
+
+type GVisorDestination struct {
+	ctx      context.Context
+	logger   logger.ContextLogger
+	conn     *gonet.TCPConn
+	rewriter *Rewriter
+}
+
+func ConnectGVisor(
+	ctx context.Context, logger logger.ContextLogger,
+	sourceAddress, destinationAddress netip.Addr,
+	routeContext tun.DirectRouteContext,
+	stack *stack.Stack,
+	bindAddress4, bindAddress6 netip.Addr,
+) (*GVisorDestination, error) {
+	var (
+		bindAddress tcpip.Address
+		wq          waiter.Queue
+		endpoint    tcpip.Endpoint
+		gErr        tcpip.Error
+	)
+	if !destinationAddress.Is6() {
+		if !bindAddress4.IsValid() {
+			return nil, E.New("missing IPv4 interface address")
+		}
+		bindAddress = tun.AddressFromAddr(bindAddress4)
+		endpoint, gErr = stack.NewRawEndpoint(header.ICMPv4ProtocolNumber, header.IPv4ProtocolNumber, &wq, true)
+	} else {
+		if !bindAddress6.IsValid() {
+			return nil, E.New("missing IPv6 interface address")
+		}
+		bindAddress = tun.AddressFromAddr(bindAddress6)
+		endpoint, gErr = stack.NewRawEndpoint(header.ICMPv6ProtocolNumber, header.IPv6ProtocolNumber, &wq, true)
+	}
+	if gErr != nil {
+		return nil, gonet.TranslateNetstackError(gErr)
+	}
+	gErr = endpoint.Bind(tcpip.FullAddress{
+		NIC:  1,
+		Addr: bindAddress,
+	})
+	if gErr != nil {
+		return nil, gonet.TranslateNetstackError(gErr)
+	}
+	gErr = endpoint.Connect(tcpip.FullAddress{
+		NIC:  1,
+		Addr: tun.AddressFromAddr(destinationAddress),
+	})
+	if gErr != nil {
+		return nil, gonet.TranslateNetstackError(gErr)
+	}
+	endpoint.SocketOptions().SetHeaderIncluded(true)
+	rewriter := NewRewriter(bindAddress4, bindAddress6)
+	rewriter.CreateSession(tun.DirectRouteSession{Source: sourceAddress, Destination: destinationAddress}, routeContext)
+	destination := &GVisorDestination{
+		ctx:      ctx,
+		logger:   logger,
+		conn:     gonet.NewTCPConn(&wq, endpoint),
+		rewriter: rewriter,
+	}
+	go destination.loopRead()
+	return destination, nil
+}
+
+func (d *GVisorDestination) loopRead() {
+	for {
+		buffer := buf.NewPacket()
+		n, err := d.conn.Read(buffer.FreeBytes())
+		if err != nil {
+			buffer.Release()
+			if !E.IsClosed(err) {
+				d.logger.ErrorContext(d.ctx, E.Cause(err, "receive ICMP echo reply"))
+			}
+			return
+		}
+		buffer.Truncate(n)
+		_, err = d.rewriter.WriteBack(buffer.Bytes())
+		if err != nil {
+			d.logger.ErrorContext(d.ctx, E.Cause(err, "write ICMP echo reply"))
+		}
+		buffer.Release()
+	}
+}
+
+func (d *GVisorDestination) WritePacket(packet *buf.Buffer) error {
+	d.rewriter.RewritePacket(packet.Bytes())
+	return common.Error(d.conn.Write(packet.Bytes()))
+}
+
+func (d *GVisorDestination) Close() error {
+	return d.conn.Close()
+}