Add EXP_UDPConn interface

common/bufio/bind.go

@@ -18,10 +18,25 @@ type bindPacketConn struct {
 	addr net.Addr
 }
 
+type bindUDPConn struct {
+	bindPacketConn
+	N.EXP_UDPConn
+}
+
 func NewBindPacketConn(conn net.PacketConn, addr net.Addr) BindPacketConn {
-	return &bindPacketConn{
+	if udpConn, isUDPConn := conn.(N.EXP_UDPConn); isUDPConn {
-		NewPacketConn(conn),
+		return &bindUDPConn{
-		addr,
+			bindPacketConn{
+				NewPacketConn(conn),
+				addr,
+			},
+			udpConn,
+		}
+	} else {
+		return &bindPacketConn{
+			NewPacketConn(conn),
+			addr,
+		}
 	}
 }
 
@@ -61,16 +76,36 @@ type UnbindPacketConn struct {
 }
 
 func NewUnbindPacketConn(conn net.Conn) N.NetPacketConn {
-	return &UnbindPacketConn{
+	if udpConn, isUDPConn := conn.(N.EXP_UDPConn); isUDPConn {
-		NewExtendedConn(conn),
+		return &UnbindUDPConn{
-		M.SocksaddrFromNet(conn.RemoteAddr()),
+			UnbindPacketConn{
+				NewExtendedConn(conn),
+				M.SocksaddrFromNet(conn.RemoteAddr()),
+			},
+			udpConn,
+		}
+	} else {
+		return &UnbindPacketConn{
+			NewExtendedConn(conn),
+			M.SocksaddrFromNet(conn.RemoteAddr()),
+		}
 	}
 }
 
 func NewUnbindPacketConnWithAddr(conn net.Conn, addr M.Socksaddr) N.NetPacketConn {
-	return &UnbindPacketConn{
+	if udpConn, isUDPConn := conn.(N.EXP_UDPConn); isUDPConn {
-		NewExtendedConn(conn),
+		return &UnbindUDPConn{
-		addr,
+			UnbindPacketConn{
+				NewExtendedConn(conn),
+				addr,
+			},
+			udpConn,
+		}
+	} else {
+		return &UnbindPacketConn{
+			NewExtendedConn(conn),
+			addr,
+		}
 	}
 }
 
@@ -110,3 +145,22 @@ func (c *UnbindPacketConn) CreateReadWaiter() (N.PacketReadWaiter, bool) {
 func (c *UnbindPacketConn) Upstream() any {
 	return c.ExtendedConn
 }
+
+var _ N.EXP_UDPConn = (*UnbindUDPConn)(nil)
+
+type UnbindUDPConn struct {
+	UnbindPacketConn
+	N.EXP_UDPConn
+}
+
+func (c *UnbindUDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *net.UDPAddr, err error) {
+	n, oobn, flags, addr, err = c.EXP_UDPConn.ReadMsgUDP(b, oob)
+	if err == nil {
+		addr = c.addr.UDPAddr()
+	}
+	return
+}
+
+func (c *UnbindUDPConn) WriteMsgUDP(b, oob []byte, _ *net.UDPAddr) (n, oobn int, err error) {
+	return c.EXP_UDPConn.WriteMsgUDP(b, oob, c.addr.UDPAddr())
+}

common/bufio/conn.go

@@ -148,40 +148,40 @@ type ExtendedConnWrapper struct {
 	writer N.ExtendedWriter
 }
 
-func (w *ExtendedConnWrapper) ReadBuffer(buffer *buf.Buffer) error {
+func (c *ExtendedConnWrapper) ReadBuffer(buffer *buf.Buffer) error {
-	return w.reader.ReadBuffer(buffer)
+	return c.reader.ReadBuffer(buffer)
 }
 
-func (w *ExtendedConnWrapper) WriteBuffer(buffer *buf.Buffer) error {
+func (c *ExtendedConnWrapper) WriteBuffer(buffer *buf.Buffer) error {
-	return w.writer.WriteBuffer(buffer)
+	return c.writer.WriteBuffer(buffer)
 }
 
-func (w *ExtendedConnWrapper) ReadFrom(r io.Reader) (n int64, err error) {
+func (c *ExtendedConnWrapper) ReadFrom(r io.Reader) (n int64, err error) {
-	return Copy(w.writer, r)
+	return Copy(c.writer, r)
 }
 
-func (r *ExtendedConnWrapper) WriteTo(w io.Writer) (n int64, err error) {
+func (c *ExtendedConnWrapper) WriteTo(w io.Writer) (n int64, err error) {
-	return Copy(w, r.reader)
+	return Copy(w, c.reader)
 }
 
-func (w *ExtendedConnWrapper) UpstreamReader() any {
+func (c *ExtendedConnWrapper) UpstreamReader() any {
-	return w.reader
+	return c.reader
 }
 
-func (w *ExtendedConnWrapper) ReaderReplaceable() bool {
+func (c *ExtendedConnWrapper) ReaderReplaceable() bool {
 	return true
 }
 
-func (w *ExtendedConnWrapper) UpstreamWriter() any {
+func (c *ExtendedConnWrapper) UpstreamWriter() any {
-	return w.writer
+	return c.writer
 }
 
-func (w *ExtendedConnWrapper) WriterReplaceable() bool {
+func (c *ExtendedConnWrapper) WriterReplaceable() bool {
 	return true
 }
 
-func (w *ExtendedConnWrapper) Upstream() any {
+func (c *ExtendedConnWrapper) Upstream() any {
-	return w.Conn
+	return c.Conn
 }
 
 func NewExtendedConn(conn net.Conn) N.ExtendedConn {

common/network/conn.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"io"
 	"net"
+	"syscall"
 	"time"
 
 	"github.com/sagernet/sing/common"
@@ -85,6 +86,15 @@ type BindPacketConn interface {
 	net.Conn
 }
 
+// EXP_UDPConn is a interface used x/net/ipv4 and quic-go
+type EXP_UDPConn interface {
+	net.PacketConn
+	syscall.Conn
+	SetReadBuffer(bytes int) error
+	ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *net.UDPAddr, err error)
+	WriteMsgUDP(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error)
+}
+
 type UDPHandler interface {
 	NewPacket(ctx context.Context, conn PacketConn, buffer *buf.Buffer, metadata M.Metadata) error
 }