From fbca37c42b444429c4841983306553ffa2109cc0 Mon Sep 17 00:00:00 2001
From: embeddedlove <118641459+embeddedlove@users.noreply.github.com>
Date: Thu, 22 Dec 2022 19:25:30 +0800
Subject: [PATCH] Feature: REDIRECT support IPv6 (#2473)

---
 listener/redir/tcp_linux.go | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/listener/redir/tcp_linux.go b/listener/redir/tcp_linux.go
index a8b6d967..b65c34ee 100644
--- a/listener/redir/tcp_linux.go
+++ b/listener/redir/tcp_linux.go
@@ -32,7 +32,11 @@ func parserPacket(conn net.Conn) (socks5.Addr, error) {
 	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 socks5.AddrFromStdAddrPort(addr), err
@@ -48,3 +52,13 @@ func getorigdst(fd uintptr) (netip.AddrPort, error) {
 	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))
+	if err := socketcall(GETSOCKOPT, fd, syscall.IPPROTO_IPV6, IP6T_SO_ORIGINAL_DST, uintptr(unsafe.Pointer(&addr)), uintptr(unsafe.Pointer(&size)), 0); err != nil {
+		return netip.AddrPort{}, err
+	}
+	port := binary.BigEndian.Uint16((*(*[2]byte)(unsafe.Pointer(&addr.Port)))[:])
+	return netip.AddrPortFrom(netip.AddrFrom16(addr.Addr), port), nil
+}