Chore: update tproxy udp packet read logic

listener/tproxy/packet.go

@@ -2,12 +2,13 @@ package tproxy
 
 import (
 	"net"
+	"net/netip"
 
 	"github.com/Dreamacro/clash/common/pool"
 )
 
 type packet struct {
-	lAddr *net.UDPAddr
+	lAddr netip.AddrPort
 	buf   []byte
 }
 
@@ -17,7 +18,7 @@ func (c *packet) Data() []byte {
 
 // WriteBack opens a new socket binding `addr` to write UDP packet back
 func (c *packet) WriteBack(b []byte, addr net.Addr) (n int, err error) {
-	tc, err := dialUDP("udp", addr.(*net.UDPAddr), c.lAddr)
+	tc, err := dialUDP("udp", addr.(*net.UDPAddr).AddrPort(), c.lAddr)
 	if err != nil {
 		n = 0
 		return
@@ -29,7 +30,7 @@ func (c *packet) WriteBack(b []byte, addr net.Addr) (n int, err error) {
 
 // LocalAddr returns the source IP/Port of UDP Packet
 func (c *packet) LocalAddr() net.Addr {
-	return c.lAddr
+	return &net.UDPAddr{IP: c.lAddr.Addr().AsSlice(), Port: int(c.lAddr.Port()), Zone: c.lAddr.Addr().Zone()}
 }
 
 func (c *packet) Drop() {

listener/tproxy/udp.go

@@ -2,6 +2,7 @@ package tproxy
 
 import (
 	"net"
+	"net/netip"
 
 	"github.com/Dreamacro/clash/adapter/inbound"
 	"github.com/Dreamacro/clash/common/pool"
@@ -58,7 +59,7 @@ func NewUDP(addr string, in chan<- *inbound.PacketAdapter) (*UDPListener, error)
 		oob := make([]byte, 1024)
 		for {
 			buf := pool.Get(pool.UDPBufferSize)
-			n, oobn, _, lAddr, err := c.ReadMsgUDP(buf, oob)
+			n, oobn, _, lAddr, err := c.ReadMsgUDPAddrPort(buf, oob)
 			if err != nil {
 				pool.Put(buf)
 				if rl.closed {
@@ -67,19 +68,19 @@ func NewUDP(addr string, in chan<- *inbound.PacketAdapter) (*UDPListener, error)
 				continue
 			}
 
-			rAddr, err := getOrigDst(oob, oobn)
+			rAddr, err := getOrigDst(oob[:oobn])
 			if err != nil {
 				continue
 			}
-			handlePacketConn(l, in, buf[:n], lAddr, rAddr)
+			handlePacketConn(in, buf[:n], lAddr, rAddr)
 		}
 	}()
 
 	return rl, nil
 }
 
-func handlePacketConn(pc net.PacketConn, in chan<- *inbound.PacketAdapter, buf []byte, lAddr *net.UDPAddr, rAddr *net.UDPAddr) {
+func handlePacketConn(in chan<- *inbound.PacketAdapter, buf []byte, lAddr, rAddr netip.AddrPort) {
-	target := socks5.ParseAddrToSocksAddr(rAddr)
+	target := socks5.AddrFromStdAddrPort(rAddr)
 	pkt := &packet{
 		lAddr: lAddr,
 		buf:   buf,

listener/tproxy/udp_linux.go

@@ -3,13 +3,14 @@
 package tproxy
 
 import (
-	"encoding/binary"
-	"errors"
 	"fmt"
 	"net"
+	"net/netip"
 	"os"
 	"strconv"
 	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 const (
@@ -19,7 +20,7 @@ const (
 
 // dialUDP acts like net.DialUDP for transparent proxy.
 // It binds to a non-local address(`lAddr`).
-func dialUDP(network string, lAddr *net.UDPAddr, rAddr *net.UDPAddr) (*net.UDPConn, error) {
+func dialUDP(network string, lAddr, rAddr netip.AddrPort) (uc *net.UDPConn, err error) {
 	rSockAddr, err := udpAddrToSockAddr(rAddr)
 	if err != nil {
 		return nil, err
@@ -35,23 +36,25 @@ func dialUDP(network string, lAddr *net.UDPAddr, rAddr *net.UDPAddr) (*net.UDPCo
 		return nil, err
 	}
 
+	defer func() {
+		if err != nil {
+			syscall.Close(fd)
+		}
+	}()
+
 	if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err != nil {
-		syscall.Close(fd)
 		return nil, err
 	}
 
 	if err = syscall.SetsockoptInt(fd, syscall.SOL_IP, syscall.IP_TRANSPARENT, 1); err != nil {
-		syscall.Close(fd)
 		return nil, err
 	}
 
 	if err = syscall.Bind(fd, lSockAddr); err != nil {
-		syscall.Close(fd)
 		return nil, err
 	}
 
 	if err = syscall.Connect(fd, rSockAddr); err != nil {
-		syscall.Close(fd)
 		return nil, err
 	}
 
@@ -60,35 +63,26 @@ func dialUDP(network string, lAddr *net.UDPAddr, rAddr *net.UDPAddr) (*net.UDPCo
 
 	c, err := net.FileConn(fdFile)
 	if err != nil {
-		syscall.Close(fd)
 		return nil, err
 	}
 
 	return c.(*net.UDPConn), nil
 }
 
-func udpAddrToSockAddr(addr *net.UDPAddr) (syscall.Sockaddr, error) {
+func udpAddrToSockAddr(addr netip.AddrPort) (syscall.Sockaddr, error) {
-	switch {
+	if addr.Addr().Is4() {
-	case addr.IP.To4() != nil:
+		return &syscall.SockaddrInet4{Addr: addr.Addr().As4(), Port: int(addr.Port())}, nil
-		ip := [4]byte{}
-		copy(ip[:], addr.IP.To4())
-
-		return &syscall.SockaddrInet4{Addr: ip, Port: addr.Port}, nil
-
-	default:
-		ip := [16]byte{}
-		copy(ip[:], addr.IP.To16())
-
-		zoneID, err := strconv.ParseUint(addr.Zone, 10, 32)
-		if err != nil {
-			zoneID = 0
-		}
-
-		return &syscall.SockaddrInet6{Addr: ip, Port: addr.Port, ZoneId: uint32(zoneID)}, nil
 	}
+
+	zoneID, err := strconv.ParseUint(addr.Addr().Zone(), 10, 32)
+	if err != nil {
+		zoneID = 0
+	}
+
+	return &syscall.SockaddrInet6{Addr: addr.Addr().As16(), Port: int(addr.Port()), ZoneId: uint32(zoneID)}, nil
 }
 
-func udpAddrFamily(net string, lAddr, rAddr *net.UDPAddr) int {
+func udpAddrFamily(net string, lAddr, rAddr netip.AddrPort) int {
 	switch net[len(net)-1] {
 	case '4':
 		return syscall.AF_INET
@@ -96,29 +90,35 @@ func udpAddrFamily(net string, lAddr, rAddr *net.UDPAddr) int {
 		return syscall.AF_INET6
 	}
 
-	if (lAddr == nil || lAddr.IP.To4() != nil) && (rAddr == nil || lAddr.IP.To4() != nil) {
+	if lAddr.Addr().Is4() && rAddr.Addr().Is4() {
 		return syscall.AF_INET
 	}
 	return syscall.AF_INET6
 }
 
-func getOrigDst(oob []byte, oobn int) (*net.UDPAddr, error) {
+func getOrigDst(oob []byte) (netip.AddrPort, error) {
-	msgs, err := syscall.ParseSocketControlMessage(oob[:oobn])
+	// oob contains socket control messages which we need to parse.
+	scms, err := unix.ParseSocketControlMessage(oob)
 	if err != nil {
-		return nil, err
+		return netip.AddrPort{}, fmt.Errorf("parse control message: %w", err)
 	}
 
-	for _, msg := range msgs {
+	// retrieve the destination address from the SCM.
-		if msg.Header.Level == syscall.SOL_IP && msg.Header.Type == syscall.IP_RECVORIGDSTADDR {
+	sa, err := unix.ParseOrigDstAddr(&scms[0])
-			ip := net.IP(msg.Data[4:8])
+	if err != nil {
-			port := binary.BigEndian.Uint16(msg.Data[2:4])
+		return netip.AddrPort{}, fmt.Errorf("retrieve destination: %w", err)
-			return &net.UDPAddr{IP: ip, Port: int(port)}, nil
-		} else if msg.Header.Level == syscall.SOL_IPV6 && msg.Header.Type == IPV6_RECVORIGDSTADDR {
-			ip := net.IP(msg.Data[8:24])
-			port := binary.BigEndian.Uint16(msg.Data[2:4])
-			return &net.UDPAddr{IP: ip, Port: int(port)}, nil
-		}
 	}
 
-	return nil, errors.New("cannot find origDst")
+	// encode the destination address into a cmsg.
+	var rAddr netip.AddrPort
+	switch v := sa.(type) {
+	case *unix.SockaddrInet4:
+		rAddr = netip.AddrPortFrom(netip.AddrFrom4(v.Addr), uint16(v.Port))
+	case *unix.SockaddrInet6:
+		rAddr = netip.AddrPortFrom(netip.AddrFrom16(v.Addr), uint16(v.Port))
+	default:
+		return netip.AddrPort{}, fmt.Errorf("unsupported address type: %T", v)
+	}
+
+	return rAddr, nil
 }

listener/tproxy/udp_other.go

@@ -5,12 +5,13 @@ package tproxy
 import (
 	"errors"
 	"net"
+	"net/netip"
 )
 
-func getOrigDst(oob []byte, oobn int) (*net.UDPAddr, error) {
+func getOrigDst(oob []byte) (netip.AddrPort, error) {
-	return nil, errors.New("UDP redir not supported on current platform")
+	return netip.AddrPort{}, errors.New("UDP redir not supported on current platform")
 }
 
-func dialUDP(network string, lAddr *net.UDPAddr, rAddr *net.UDPAddr) (*net.UDPConn, error) {
+func dialUDP(network string, lAddr, rAddr netip.AddrPort) (*net.UDPConn, error) {
 	return nil, errors.New("UDP redir not supported on current platform")
 }

transport/socks5/socks5.go

@@ -398,6 +398,21 @@ func ParseAddrToSocksAddr(addr net.Addr) Addr {
 	return parsed
 }
 
+func AddrFromStdAddrPort(addrPort netip.AddrPort) Addr {
+	addr := addrPort.Addr()
+	if addr.Is4() {
+		ip4 := addr.As4()
+		return []byte{AtypIPv4, ip4[0], ip4[1], ip4[2], ip4[3], byte(addrPort.Port() >> 8), byte(addrPort.Port())}
+	}
+
+	buf := make([]byte, 1+net.IPv6len+2)
+	buf[0] = AtypIPv6
+	copy(buf[1:], addr.AsSlice())
+	buf[1+net.IPv6len] = byte(addrPort.Port() >> 8)
+	buf[1+net.IPv6len+1] = byte(addrPort.Port())
+	return buf
+}
+
 // DecodeUDPPacket split `packet` to addr payload, and this function is mutable with `packet`
 func DecodeUDPPacket(packet []byte) (addr Addr, payload []byte, err error) {
 	if len(packet) < 5 {