Fix bad type cast in dispatcher

common/buf/reader.go

@@ -7,7 +7,7 @@ import (
 	"github.com/xtls/xray-core/common/errors"
 )
 
-func readOneUDP(r io.Reader) (*Buffer, error) {
+func ReadOneUDP(r io.Reader) (*Buffer, error) {
 	b := New()
 	for i := 0; i < 64; i++ {
 		_, err := b.ReadFrom(r)
@@ -166,7 +166,7 @@ type PacketReader struct {
 
 // ReadMultiBuffer implements Reader.
 func (r *PacketReader) ReadMultiBuffer() (MultiBuffer, error) {
-	b, err := readOneUDP(r.Reader)
+	b, err := ReadOneUDP(r.Reader)
 	if err != nil {
 		return nil, err
 	}

common/singbridge/handler.go

@@ -2,11 +2,10 @@ package singbridge
 
 import (
 	"context"
-	"io"
 
+	"github.com/sagernet/sing/common/bufio"
 	M "github.com/sagernet/sing/common/metadata"
 	N "github.com/sagernet/sing/common/network"
-	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/session"
@@ -40,9 +39,10 @@ func (d *Dispatcher) NewConnection(ctx context.Context, conn net.Conn, metadata
 }
 
 func (d *Dispatcher) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata M.Metadata) error {
+	packetConn := &PacketConn{bufio.NewBindPacketConn(conn.(net.PacketConn), metadata.Destination)}
 	return d.upstream.DispatchLink(ctx, ToDestination(metadata.Destination, net.Network_UDP), &transport.Link{
-		Reader: buf.NewPacketReader(conn.(io.Reader)),
-		Writer: buf.NewWriter(conn.(io.Writer)),
+		Reader: packetConn,
+		Writer: packetConn,
 	})
 }
 

common/singbridge/reader.go

@@ -14,6 +14,9 @@ var (
 	_ buf.Reader        = (*Conn)(nil)
 	_ buf.TimeoutReader = (*Conn)(nil)
 	_ buf.Writer        = (*Conn)(nil)
+	_ buf.Reader        = (*PacketConn)(nil)
+	_ buf.TimeoutReader = (*PacketConn)(nil)
+	_ buf.Writer        = (*PacketConn)(nil)
 )
 
 type Conn struct {
@@ -64,3 +67,30 @@ func (c *Conn) WriteMultiBuffer(bufferList buf.MultiBuffer) error {
 	}
 	return nil
 }
+
+type PacketConn struct {
+	net.Conn
+}
+
+func (c *PacketConn) ReadMultiBuffer() (buf.MultiBuffer, error) {
+	buffer, err := buf.ReadOneUDP(c.Conn)
+	if err != nil {
+		return nil, err
+	}
+	return buf.MultiBuffer{buffer}, nil
+}
+
+func (c *PacketConn) ReadMultiBufferTimeout(duration time.Duration) (buf.MultiBuffer, error) {
+	err := c.SetReadDeadline(time.Now().Add(duration))
+	if err != nil {
+		return nil, err
+	}
+	defer c.SetReadDeadline(time.Time{})
+	return c.ReadMultiBuffer()
+}
+
+func (c *PacketConn) WriteMultiBuffer(mb buf.MultiBuffer) error {
+	mb, err := buf.WriteMultiBuffer(c.Conn, mb)
+	buf.ReleaseMulti(mb)
+	return err
+}