From fcd55808759ccaf89422c51673cff206e3dd4d01 Mon Sep 17 00:00:00 2001
From: gVisor bot <gvisor-bot@google.com>
Date: Thu, 22 Dec 2022 08:45:11 +0800
Subject: [PATCH] chore: linux ipv6 REDIRECT (#311)

---
 listener/redir/tcp_linux.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/listener/redir/tcp_linux.go b/listener/redir/tcp_linux.go
index c4a47d8e..949ca717 100644
--- a/listener/redir/tcp_linux.go
+++ b/listener/redir/tcp_linux.go
@@ -29,6 +29,9 @@ func parserPacket(conn net.Conn) (socks5.Addr, error) {
 
 	rc.Control(func(fd uintptr) {
 		addr, err = getorigdst(fd)
+		if err != nil {
+			addr, err = getorigdst6(fd)
+		}
 	})
 
 	return addr, err
@@ -49,3 +52,17 @@ func getorigdst(fd uintptr) (socks5.Addr, error) {
 	addr[1+net.IPv4len], addr[1+net.IPv4len+1] = port[0], port[1]
 	return addr, nil
 }
+
+func getorigdst6(fd uintptr) (socks5.Addr, error) {
+	raw := syscall.RawSockaddrInet6{}
+	siz := uint32(unsafe.Sizeof(raw))
+	if err := socketcall(GETSOCKOPT, fd, syscall.IPPROTO_IPV6, IP6T_SO_ORIGINAL_DST, uintptr(unsafe.Pointer(&raw)), uintptr(unsafe.Pointer(&siz)), 0); err != nil {
+		return nil, err
+	}
+	addr := make([]byte, 1+net.IPv6len+2)
+	addr[0] = socks5.AtypIPv6
+	copy(addr[1:1+net.IPv6len], raw.Addr[:])
+	port := (*[2]byte)(unsafe.Pointer(&raw.Port)) // big-endian
+	addr[1+net.IPv6len], addr[1+net.IPv6len+1] = port[0], port[1]
+	return addr, nil
+}