feat: support to mark direct traffic (#24)

control/utils.go

@@ -0,0 +1,90 @@
+/*
+ * SPDX-License-Identifier: AGPL-3.0-only
+ * Copyright (c) 2022-2023, v2rayA Organization <team@v2raya.org>
+ */
+
+package control
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"github.com/mzz2017/softwind/netproxy"
+	"github.com/v2rayA/dae/common/consts"
+	internal "github.com/v2rayA/dae/pkg/ebpf_internal"
+	"golang.org/x/sys/unix"
+	"net/netip"
+	"os"
+	"syscall"
+)
+
+func (c *ControlPlaneCore) RetrieveRoutingResult(src, dst netip.AddrPort, l4proto uint8) (result *bpfRoutingResult, err error) {
+	srcIp6 := src.Addr().As16()
+	dstIp6 := dst.Addr().As16()
+
+	tuples := &bpfTuples{
+		Sip:     struct{ U6Addr8 [16]uint8 }{U6Addr8: srcIp6},
+		Sport:   internal.Htons(src.Port()),
+		Dip:     struct{ U6Addr8 [16]uint8 }{U6Addr8: dstIp6},
+		Dport:   internal.Htons(dst.Port()),
+		L4proto: l4proto,
+	}
+
+	var routingResult bpfRoutingResult
+	if err := c.bpf.RoutingTuplesMap.Lookup(tuples, &routingResult); err != nil {
+		return nil, fmt.Errorf("reading map: key [%v, %v, %v]: %w", src.String(), l4proto, dst.String(), err)
+	}
+	return &routingResult, nil
+}
+
+func RetrieveOriginalDest(oob []byte) netip.AddrPort {
+	msgs, err := syscall.ParseSocketControlMessage(oob)
+	if err != nil {
+		return netip.AddrPort{}
+	}
+	for _, msg := range msgs {
+		if msg.Header.Level == syscall.SOL_IP && msg.Header.Type == syscall.IP_RECVORIGDSTADDR {
+			ip := msg.Data[4:8]
+			port := binary.BigEndian.Uint16(msg.Data[2:4])
+			return netip.AddrPortFrom(netip.AddrFrom4(*(*[4]byte)(ip)), port)
+		} else if msg.Header.Level == syscall.SOL_IPV6 && msg.Header.Type == unix.IPV6_RECVORIGDSTADDR {
+			ip := msg.Data[8:24]
+			port := binary.BigEndian.Uint16(msg.Data[2:4])
+			return netip.AddrPortFrom(netip.AddrFrom16(*(*[16]byte)(ip)), port)
+		}
+	}
+	return netip.AddrPort{}
+}
+
+func checkIpforward(ifname string, ipversion consts.IpVersionStr) error {
+	path := fmt.Sprintf("/proc/sys/net/ipv%v/conf/%v/forwarding", ipversion, ifname)
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+	if bytes.Equal(bytes.TrimSpace(b), []byte("1")) {
+		return nil
+	}
+	return fmt.Errorf("ipforward on %v is off: %v; see https://github.com/v2rayA/dae#enable-ip-forwarding", ifname, path)
+}
+
+func CheckIpforward(ifname string) error {
+	if err := checkIpforward(ifname, consts.IpVersionStr_4); err != nil {
+		return err
+	}
+	if err := checkIpforward(ifname, consts.IpVersionStr_6); err != nil {
+		return err
+	}
+	return nil
+}
+
+func GetNetwork(network string, mark uint32) string {
+	if mark == 0 {
+		return network
+	} else {
+		return netproxy.MagicNetwork{
+			Network: network,
+			Mark:    mark,
+		}.Encode()
+	}
+}