fix udp original destination on windows

proxy/dokodemo/fakeudp_other.go

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

proxy/dokodemo/fakeudp_windows.go

@@ -0,0 +1,27 @@
+//go:build windows
+// +build windows
+
+package dokodemo
+
+import (
+	"net"
+	"syscall"
+)
+
+func FakeUDP(addr *net.UDPAddr, mark int) (net.PacketConn, error) {
+	udpConn, err := net.ListenUDP("udp", addr)
+	if err != nil {
+		return udpConn, err
+	}
+	rawConn, err := udpConn.SyscallConn()
+	if err != nil {
+		return nil, err
+	}
+	err = rawConn.Control(func(fd uintptr) {
+		syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return udpConn, nil
+}

transport/internet/sockopt_windows.go

@@ -11,6 +11,7 @@ import (
 	"unsafe"
 
 	"github.com/xtls/xray-core/common/errors"
+	"golang.org/x/sys/windows"
 )
 
 const (
@@ -142,6 +143,15 @@ func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig)
 		}
 	}
 
+	if config.ReceiveOriginalDestAddress && isUDPSocket(network) {
+		if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IP, windows.IP_PKTINFO, 1); err != nil {
+			return errors.New("failed to set IP_PKTINFO").Base(err)
+		}
+		if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IPV6, windows.IPV6_PKTINFO, 1); err != nil {
+			return errors.New("failed to set IPV6_PKTINFO").Base(err)
+		}
+	}
+
 	if len(config.CustomSockopt) > 0 {
 		for _, custom := range config.CustomSockopt {
 			if custom.System != "" && custom.System != runtime.GOOS {

transport/internet/udp/hub_other.go

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

transport/internet/udp/hub_windows.go

@@ -0,0 +1,54 @@
+//go:build windows
+// +build windows
+
+package udp
+
+import (
+	"encoding/binary"
+	"unsafe"
+
+	"github.com/xtls/xray-core/common/buf"
+	"github.com/xtls/xray-core/common/net"
+	"golang.org/x/sys/windows"
+)
+
+func RetrieveOriginalDest(oob []byte) net.Destination {
+	dest := net.Destination{}
+	port := binary.LittleEndian.Uint16(oob[:2])
+	buf := buf.FromBytes(oob[2:])
+	defer buf.Release()
+
+	for !buf.IsEmpty() {
+		cm := &windows.WSACMSGHDR{}
+		len := make([]byte, unsafe.Sizeof(cm.Len))
+		nRead, err := buf.Read(len)
+		if err != nil {
+			return dest
+		}
+		cm.Len = uintptr(binary.LittleEndian.Uint16(len))
+		binary.Read(buf, binary.LittleEndian, &cm.Level)
+		binary.Read(buf, binary.LittleEndian, &cm.Type)
+		nRead += 8 // len cm.Level + cm.Type
+
+		if cm.Type == windows.IP_PKTINFO {
+			if cm.Level == windows.IPPROTO_IP { // IPv4
+				pktinf := &windows.IN_PKTINFO{}
+				binary.Read(buf, binary.LittleEndian, pktinf)
+				return net.UDPDestination(net.IPAddress(pktinf.Addr[:]), net.Port(port))
+			} else { // IPv6
+				pktinfv6 := &windows.IN6_PKTINFO{}
+				binary.Read(buf, binary.LittleEndian, pktinfv6)
+				return net.UDPDestination(net.IPAddress(pktinfv6.Addr[:]), net.Port(port))
+			}
+		}
+		buf.Advance(int32(cm.Len) - int32(nRead))
+	}
+	return dest
+}
+
+func ReadUDPMsg(conn *net.UDPConn, payload []byte, oob []byte) (int, int, int, *net.UDPAddr, error) {
+	udpAddr, _ := net.ResolveUDPAddr(conn.LocalAddr().Network(), conn.LocalAddr().String())
+	binary.LittleEndian.PutUint16(oob[:2], uint16(udpAddr.Port))
+	n, oobn, flags, addr, err := conn.ReadMsgUDP(payload, oob[2:])
+	return n, oobn + 2, flags, addr, err
+}