Fix: fakeip udp should not replace with another ip

adapter/inbound/util.go

@@ -1,13 +1,13 @@
 package inbound
 
 import (
+	"github.com/Dreamacro/clash/common/nnip"
 	"net"
 	"net/http"
 	"net/netip"
 	"strconv"
 	"strings"
 
-	"github.com/Dreamacro/clash/common/nnip"
 	C "github.com/Dreamacro/clash/constant"
 	"github.com/Dreamacro/clash/transport/socks5"
 )
@@ -26,7 +26,8 @@ func parseSocksAddr(target socks5.Addr) *C.Metadata {
 		metadata.DstIP = nnip.IpToAddr(net.IP(target[1 : 1+net.IPv4len]))
 		metadata.DstPort = strconv.Itoa((int(target[1+net.IPv4len]) << 8) | int(target[1+net.IPv4len+1]))
 	case socks5.AtypIPv6:
-		metadata.DstIP = nnip.IpToAddr(net.IP(target[1 : 1+net.IPv6len]))
+		ip6, _ := netip.AddrFromSlice(target[1 : 1+net.IPv6len])
+		metadata.DstIP = ip6.Unmap()
 		metadata.DstPort = strconv.Itoa((int(target[1+net.IPv6len]) << 8) | int(target[1+net.IPv6len+1]))
 	}
 

tunnel/connection.go

@@ -3,26 +3,17 @@ package tunnel
 import (
 	"errors"
 	"net"
+	"net/netip"
 	"time"
 
 	N "github.com/Dreamacro/clash/common/net"
 	"github.com/Dreamacro/clash/common/pool"
-	"github.com/Dreamacro/clash/component/resolver"
 	C "github.com/Dreamacro/clash/constant"
 )
 
 func handleUDPToRemote(packet C.UDPPacket, pc C.PacketConn, metadata *C.Metadata) error {
 	defer packet.Drop()
 
-	// local resolve UDP dns
-	if !metadata.Resolved() {
-		ip, err := resolver.ResolveIP(metadata.Host)
-		if err != nil {
-			return err
-		}
-		metadata.DstIP = ip
-	}
-
 	addr := metadata.UDPAddr()
 	if addr == nil {
 		return errors.New("udp addr invalid")
@@ -32,29 +23,36 @@ func handleUDPToRemote(packet C.UDPPacket, pc C.PacketConn, metadata *C.Metadata
 		return err
 	}
 	// reset timeout
-	pc.SetReadDeadline(time.Now().Add(udpTimeout))
+	_ = pc.SetReadDeadline(time.Now().Add(udpTimeout))
 
 	return nil
 }
 
-func handleUDPToLocal(packet C.UDPPacket, pc net.PacketConn, key string, fAddr net.Addr) {
+func handleUDPToLocal(packet C.UDPPacket, pc net.PacketConn, key string, oAddr, fAddr netip.Addr) {
 	buf := pool.Get(pool.UDPBufferSize)
-	defer pool.Put(buf)
+	defer func() {
-	defer natTable.Delete(key)
+		_ = pc.Close()
-	defer pc.Close()
+		natTable.Delete(key)
+		_ = pool.Put(buf)
+	}()
 
 	for {
-		pc.SetReadDeadline(time.Now().Add(udpTimeout))
+		_ = pc.SetReadDeadline(time.Now().Add(udpTimeout))
 		n, from, err := pc.ReadFrom(buf)
 		if err != nil {
 			return
 		}
 
-		if fAddr != nil {
+		fromUDPAddr := from.(*net.UDPAddr)
-			from = fAddr
+		if fAddr.IsValid() {
+			fromAddr, _ := netip.AddrFromSlice(fromUDPAddr.IP)
+			fromAddr.Unmap()
+			if oAddr == fromAddr {
+				fromUDPAddr.IP = fAddr.AsSlice()
+			}
 		}
 
-		_, err = packet.WriteBack(buf[:n], from)
+		_, err = packet.WriteBack(buf[:n], fromUDPAddr)
 		if err != nil {
 			return
 		}

tunnel/tunnel.go

@@ -209,9 +209,9 @@ func handleUDPConn(packet *inbound.PacketAdapter) {
 	}
 
 	// make a fAddr if request ip is fakeip
-	var fAddr net.Addr
+	var fAddr netip.Addr
 	if resolver.IsExistFakeIP(metadata.DstIP) {
-		fAddr = metadata.UDPAddr()
+		fAddr = metadata.DstIP
 	}
 
 	if err := preHandleMetadata(metadata); err != nil {
@@ -219,6 +219,15 @@ func handleUDPConn(packet *inbound.PacketAdapter) {
 		return
 	}
 
+	// local resolve UDP dns
+	if !metadata.Resolved() {
+		ip, err := resolver.ResolveIP(metadata.Host)
+		if err != nil {
+			return
+		}
+		metadata.DstIP = ip
+	}
+
 	key := packet.LocalAddr().String()
 
 	handle := func() bool {
@@ -288,7 +297,8 @@ func handleUDPConn(packet *inbound.PacketAdapter) {
 			log.Infoln("[UDP] %s --> %s doesn't match any rule using DIRECT", metadata.SourceDetail(), metadata.RemoteAddress())
 		}
 
-		go handleUDPToLocal(packet.UDPPacket, pc, key, fAddr)
+		oAddr := metadata.DstIP
+		go handleUDPToLocal(packet.UDPPacket, pc, key, oAddr, fAddr)
 
 		natTable.Set(key, pc)
 		handle()