From 2b6dd2a90993dd4a406c22e5fa4f4e4137946b2e Mon Sep 17 00:00:00 2001
From: Yonas Yanfa <yonas.y@gmail.com>
Date: Thu, 25 May 2023 09:13:42 -0400
Subject: [PATCH] Feature: add REDIRECT IPv6 support for FreeBSD. (#2768)

Upstream patch from FreeBSD ports which adds IPv6 support.
---
 listener/redir/tcp_freebsd.go | 44 +++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/listener/redir/tcp_freebsd.go b/listener/redir/tcp_freebsd.go
index 12c4ba6..ada1c2a 100644
--- a/listener/redir/tcp_freebsd.go
+++ b/listener/redir/tcp_freebsd.go
@@ -1,12 +1,16 @@
 package redir
 
 import (
+	"encoding/binary"
 	"errors"
 	"net"
+	"net/netip"
 	"syscall"
 	"unsafe"
 
 	"github.com/Dreamacro/clash/transport/socks5"
+
+	"golang.org/x/sys/unix"
 )
 
 const (
@@ -25,28 +29,38 @@ func parserPacket(conn net.Conn) (socks5.Addr, error) {
 		return nil, err
 	}
 
-	var addr socks5.Addr
+	var addr netip.AddrPort
 
 	rc.Control(func(fd uintptr) {
-		addr, err = getorigdst(fd)
+		if ip4 := c.LocalAddr().(*net.TCPAddr).IP.To4(); ip4 != nil {
+			addr, err = getorigdst(fd)
+		} else {
+			addr, err = getorigdst6(fd)
+		}
 	})
 
-	return addr, err
+	return socks5.AddrFromStdAddrPort(addr), err
 }
 
 // Call getorigdst() from linux/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
-func getorigdst(fd uintptr) (socks5.Addr, error) {
-	raw := syscall.RawSockaddrInet4{}
-	siz := unsafe.Sizeof(raw)
-	_, _, err := syscall.Syscall6(syscall.SYS_GETSOCKOPT, fd, syscall.IPPROTO_IP, SO_ORIGINAL_DST, uintptr(unsafe.Pointer(&raw)), uintptr(unsafe.Pointer(&siz)), 0)
+func getorigdst(fd uintptr) (netip.AddrPort, error) {
+	addr := unix.RawSockaddrInet4{}
+	size := uint32(unsafe.Sizeof(addr))
+	 _, _, err := syscall.Syscall6(syscall.SYS_GETSOCKOPT, fd, syscall.IPPROTO_IP, SO_ORIGINAL_DST, uintptr(unsafe.Pointer(&addr)), uintptr(unsafe.Pointer(&size)), 0)
 	if err != 0 {
-		return nil, err
+		return netip.AddrPort{}, err
 	}
-
-	addr := make([]byte, 1+net.IPv4len+2)
-	addr[0] = socks5.AtypIPv4
-	copy(addr[1:1+net.IPv4len], raw.Addr[:])
-	port := (*[2]byte)(unsafe.Pointer(&raw.Port)) // big-endian
-	addr[1+net.IPv4len], addr[1+net.IPv4len+1] = port[0], port[1]
-	return addr, nil
+	port := binary.BigEndian.Uint16((*(*[2]byte)(unsafe.Pointer(&addr.Port)))[:])
+	return netip.AddrPortFrom(netip.AddrFrom4(addr.Addr), port), nil
+}
+
+func getorigdst6(fd uintptr) (netip.AddrPort, error) {
+	addr := unix.RawSockaddrInet6{}
+	size := uint32(unsafe.Sizeof(addr))
+	_, _, err := syscall.Syscall6(syscall.SYS_GETSOCKOPT, fd, syscall.IPPROTO_IPV6, IP6T_SO_ORIGINAL_DST, uintptr(unsafe.Pointer(&addr)), uintptr(unsafe.Pointer(&size)), 0);
+	if err != 0 {
+		return netip.AddrPort{}, err
+	}
+	port := binary.BigEndian.Uint16((*(*[2]byte)(unsafe.Pointer(&addr.Port)))[:])
+	return netip.AddrPortFrom(netip.AddrFrom16(addr.Addr), port), nil
 }