Tunnel inbound: Support TPROXY on OpenBSD as well (#6546)

https://github.com/XTLS/Xray-core/pull/6546#issuecomment-5100711574

proxy/dokodemo/fakeudp_openbsd.go

@@ -0,0 +1,58 @@
+//go:build openbsd
+// +build openbsd
+
+package dokodemo
+
+import (
+	"fmt"
+	"net"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+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")}
+	}
+
+	fd, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM, 0)
+	if err != nil {
+		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("socket open: %w", err)}
+	}
+
+	closeFD := true
+	defer func() {
+		if closeFD {
+			unix.Close(fd)
+		}
+	}()
+
+	if err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_BINDANY, 1); err != nil {
+		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("set socket option SO_BINDANY: %w", err)}
+	}
+	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)}
+	}
+
+	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)}
+	}
+
+	fdFile := os.NewFile(uintptr(fd), fmt.Sprintf("net-udp-bindany-%s", addr.String()))
+	if fdFile == nil {
+		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("convert descriptor to file")}
+	}
+	defer fdFile.Close()
+
+	packetConn, err := net.FilePacketConn(fdFile)
+	if err != nil {
+		return nil, &net.OpError{Op: "fake", Err: fmt.Errorf("convert descriptor to packet connection: %w", err)}
+	}
+
+	closeFD = false
+	return packetConn, nil
+}

proxy/dokodemo/fakeudp_other.go

@@ -1,5 +1,5 @@
-//go:build !linux
+//go:build !linux && !openbsd
-// +build !linux
+// +build !linux,!openbsd
 
 package dokodemo
 

transport/internet/sockopt_openbsd.go

@@ -0,0 +1,33 @@
+//go:build openbsd
+// +build openbsd
+
+package internet
+
+import (
+	"github.com/xtls/xray-core/common/errors"
+	"golang.org/x/sys/unix"
+)
+
+func applyOutboundSocketOptions(network string, address string, fd uintptr, config *SocketConfig) error {
+	return nil
+}
+
+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)
+		}
+		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)
+		}
+	}
+	return nil
+}
+
+func setReuseAddr(fd uintptr) error {
+	return nil
+}
+
+func setReusePort(fd uintptr) error {
+	return nil
+}

transport/internet/sockopt_other.go

@@ -1,5 +1,5 @@
-//go:build js || netbsd || openbsd || solaris
+//go:build js || netbsd || solaris
-// +build js netbsd openbsd solaris
+// +build js netbsd solaris
 
 package internet
 

transport/internet/udp/hub_openbsd.go

@@ -0,0 +1,57 @@
+//go:build openbsd
+// +build openbsd
+
+package udp
+
+import (
+	"encoding/binary"
+
+	"github.com/xtls/xray-core/common/net"
+	"golang.org/x/sys/unix"
+)
+
+func retrieveOriginalDestFromControlMessages(msgs []unix.SocketControlMessage) net.Destination {
+	var ip []byte
+	var port uint16
+	var haveAddress bool
+	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
+			}
+			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
+		}
+	}
+
+	if !haveAddress || !havePort || port == 0 {
+		return net.Destination{}
+	}
+
+	return net.UDPDestination(net.IPAddress(ip), net.Port(port))
+}
+
+func RetrieveOriginalDest(oob []byte) net.Destination {
+	msgs, err := unix.ParseSocketControlMessage(oob)
+	if err != nil {
+		return net.Destination{}
+	}
+	return retrieveOriginalDestFromControlMessages(msgs)
+}
+
+func ReadUDPMsg(conn *net.UDPConn, payload []byte, oob []byte) (int, int, int, *net.UDPAddr, error) {
+	return conn.ReadMsgUDP(payload, oob)
+}

transport/internet/udp/hub_openbsd_test.go

@@ -0,0 +1,57 @@
+//go:build openbsd
+// +build openbsd
+
+package udp
+
+import (
+	"testing"
+
+	"golang.org/x/sys/unix"
+)
+
+func TestRetrieveOriginalDestFromControlMessages(t *testing.T) {
+	msgs := []unix.SocketControlMessage{
+		{
+			Header: unix.Cmsghdr{Level: unix.IPPROTO_IP, Type: unix.IP_RECVDSTPORT},
+			Data:   []byte{0x30, 0x39},
+		},
+		{
+			Header: unix.Cmsghdr{Level: unix.IPPROTO_IP, Type: unix.IP_RECVDSTADDR},
+			Data:   []byte{203, 0, 113, 7},
+		},
+	}
+
+	dest := retrieveOriginalDestFromControlMessages(msgs)
+	if !dest.IsValid() {
+		t.Fatal("destination is invalid")
+	}
+	if got, want := dest.Address.String(), "203.0.113.7"; 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{
+		{
+			{
+				Header: unix.Cmsghdr{Level: unix.IPPROTO_IP, Type: unix.IP_RECVDSTADDR},
+				Data:   []byte{203, 0, 113, 7},
+			},
+		},
+		{
+			{
+				Header: unix.Cmsghdr{Level: unix.IPPROTO_IP, Type: unix.IP_RECVDSTPORT},
+				Data:   []byte{0x30, 0x39},
+			},
+		},
+	}
+
+	for _, msgs := range tests {
+		if dest := retrieveOriginalDestFromControlMessages(msgs); dest.IsValid() {
+			t.Fatalf("unexpected destination: %v", dest)
+		}
+	}
+}

transport/internet/udp/hub_other.go

@@ -1,5 +1,5 @@
-//go:build !linux && !freebsd && !darwin
+//go:build !linux && !freebsd && !darwin && !openbsd
-// +build !linux,!freebsd,!darwin
+// +build !linux,!freebsd,!darwin,!openbsd
 
 package udp