Tunnel inbound: SO_REUSEPORT fix and IPv6 support for the OpenBSD transparent proxy (#6624)

Completes https://github.com/XTLS/Xray-core/pull/6546
This commit is contained in:
Maksim Varentsov
2026-08-26 21:05:05 +00:00
committed by GitHub
parent dffc7ada5e
commit 25c11e2d2b
4 changed files with 110 additions and 25 deletions
+26 -6
View File
@@ -12,12 +12,29 @@ import (
)
func FakeUDP(addr *net.UDPAddr, mark int) (net.PacketConn, error) {
ip4 := addr.IP.To4()
if ip4 == nil {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("IPv6 is not supported by the OpenBSD transparent UDP patch")}
domain := unix.AF_INET6
var sockaddr unix.Sockaddr
if ip4 := addr.IP.To4(); ip4 != nil {
domain = unix.AF_INET
sa := &unix.SockaddrInet4{Port: addr.Port}
copy(sa.Addr[:], ip4)
sockaddr = sa
} else if ip6 := addr.IP.To16(); ip6 != nil {
sa := &unix.SockaddrInet6{Port: addr.Port}
copy(sa.Addr[:], ip6)
if addr.Zone != "" {
iface, err := net.InterfaceByName(addr.Zone)
if err != nil {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("resolve zone %s: %w", addr.Zone, err)}
}
sa.ZoneId = uint32(iface.Index)
}
sockaddr = sa
} else {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("unsupported address %v", addr.IP)}
}
fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
fd, err := unix.Socket(domain, unix.SOCK_DGRAM, 0)
if err != nil {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("socket open: %w", err)}
}
@@ -35,9 +52,12 @@ func FakeUDP(addr *net.UDPAddr, mark int) (net.PacketConn, error) {
if err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEADDR, 1); err != nil {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("set socket option SO_REUSEADDR: %w", err)}
}
// Several client sessions can be answered from the same original
// destination at the same time, so the address has to be shareable.
if err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("set socket option SO_REUSEPORT: %w", err)}
}
sockaddr := &unix.SockaddrInet4{Port: addr.Port}
copy(sockaddr.Addr[:], ip4)
if err = unix.Bind(fd, sockaddr); err != nil {
return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("bind %s: %w", addr.String(), err)}
}
+11 -4
View File
@@ -14,11 +14,18 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig) error {
if config.ReceiveOriginalDestAddress && isUDPSocket(network) {
if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_RECVDSTADDR, 1); err != nil {
return errors.New("failed to set IP_RECVDSTADDR").Base(err)
// Only the options matching the socket's address family are accepted,
// so one of the two pairs succeeding is enough.
err6 := unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_RECVPKTINFO, 1)
if err6 == nil {
err6 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_RECVDSTPORT, 1)
}
if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_RECVDSTPORT, 1); err != nil {
return errors.New("failed to set IP_RECVDSTPORT").Base(err)
err4 := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_RECVDSTADDR, 1)
if err4 == nil {
err4 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_RECVDSTPORT, 1)
}
if err4 != nil && err6 != nil {
return errors.New("failed to enable receiving the original destination").Base(err4)
}
}
return nil
+31 -15
View File
@@ -17,23 +17,39 @@ func retrieveOriginalDestFromControlMessages(msgs []unix.SocketControlMessage) n
var havePort bool
for _, msg := range msgs {
if msg.Header.Level != unix.IPPROTO_IP {
continue
}
switch msg.Header.Type {
case unix.IP_RECVDSTADDR:
if len(msg.Data) < 4 {
continue
switch msg.Header.Level {
case unix.IPPROTO_IP:
switch msg.Header.Type {
case unix.IP_RECVDSTADDR:
if len(msg.Data) < 4 {
continue
}
ip = append(ip[:0], msg.Data[:4]...)
haveAddress = true
case unix.IP_RECVDSTPORT:
if len(msg.Data) < 2 {
continue
}
port = binary.BigEndian.Uint16(msg.Data[:2])
havePort = true
}
ip = append(ip[:0], msg.Data[:4]...)
haveAddress = true
case unix.IP_RECVDSTPORT:
if len(msg.Data) < 2 {
continue
case unix.IPPROTO_IPV6:
switch msg.Header.Type {
case unix.IPV6_PKTINFO:
// struct in6_pktinfo: the destination address is followed by
// the interface index.
if len(msg.Data) < 16 {
continue
}
ip = append(ip[:0], msg.Data[:16]...)
haveAddress = true
case unix.IPV6_RECVDSTPORT:
if len(msg.Data) < 2 {
continue
}
port = binary.BigEndian.Uint16(msg.Data[:2])
havePort = true
}
port = binary.BigEndian.Uint16(msg.Data[:2])
havePort = true
}
}
@@ -33,6 +33,36 @@ func TestRetrieveOriginalDestFromControlMessages(t *testing.T) {
}
}
func TestRetrieveOriginalDestFromControlMessagesIPv6(t *testing.T) {
// 2001:db8::7 followed by the interface index, as in struct in6_pktinfo.
pktinfo := []byte{
0x20, 0x01, 0x0d, 0xb8, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0x07,
0x02, 0, 0, 0,
}
msgs := []unix.SocketControlMessage{
{
Header: unix.Cmsghdr{Level: unix.IPPROTO_IPV6, Type: unix.IPV6_RECVDSTPORT},
Data: []byte{0x30, 0x39},
},
{
Header: unix.Cmsghdr{Level: unix.IPPROTO_IPV6, Type: unix.IPV6_PKTINFO},
Data: pktinfo,
},
}
dest := retrieveOriginalDestFromControlMessages(msgs)
if !dest.IsValid() {
t.Fatal("destination is invalid")
}
if got, want := dest.Address.IP().String(), "2001:db8::7"; got != want {
t.Fatalf("address = %q, want %q", got, want)
}
if got, want := dest.Port.Value(), uint16(12345); got != want {
t.Fatalf("port = %d, want %d", got, want)
}
}
func TestRetrieveOriginalDestRequiresAddressAndPort(t *testing.T) {
tests := [][]unix.SocketControlMessage{
{
@@ -47,6 +77,18 @@ func TestRetrieveOriginalDestRequiresAddressAndPort(t *testing.T) {
Data: []byte{0x30, 0x39},
},
},
{
{
Header: unix.Cmsghdr{Level: unix.IPPROTO_IPV6, Type: unix.IPV6_PKTINFO},
Data: make([]byte, 20),
},
},
{
{
Header: unix.Cmsghdr{Level: unix.IPPROTO_IPV6, Type: unix.IPV6_RECVDSTPORT},
Data: []byte{0x30, 0x39},
},
},
}
for _, msgs := range tests {