From b0b043a2804712bf93f1cb3a2ff486e9e3b3a984 Mon Sep 17 00:00:00 2001
From: nadoo <287492+nadoo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 11:16:24 +0800
Subject: [PATCH] tproxy: setsockopt in listener to suuport ipv6

---
 .github/workflows/docker.yml |  2 +-
 proxy/tproxy/tproxy.go       | 59 ++++++++++++------------------------
 2 files changed, 21 insertions(+), 40 deletions(-)

diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index 373555f..84012f3 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -11,7 +11,7 @@ on:
 env:
   DOCKERHUB_REPO: nadoo/glider
   GHCR_REPO: ghcr.io/nadoo/glider
-  PLATFORMS: linux/amd64,linux/arm64,linux/arm/v7
+  PLATFORMS: linux/amd64,linux/386,linux/arm64,linux/arm/v7,linux/arm/v6
 
 jobs:
   publish:
diff --git a/proxy/tproxy/tproxy.go b/proxy/tproxy/tproxy.go
index b5c93e2..fda1fa5 100644
--- a/proxy/tproxy/tproxy.go
+++ b/proxy/tproxy/tproxy.go
@@ -1,14 +1,11 @@
 package tproxy
 
 import (
-	"bytes"
 	"encoding/binary"
 	"fmt"
 	"net"
 	"os"
-	"strconv"
 	"syscall"
-	"unsafe"
 
 	"golang.org/x/sys/unix"
 )
@@ -35,8 +32,16 @@ func ListenUDP(network string, laddr *net.UDPAddr) (*net.UDPConn, error) {
 		return nil, &net.OpError{Op: "listen", Net: network, Source: nil, Addr: laddr, Err: fmt.Errorf("set socket option: IP_TRANSPARENT: %s", err)}
 	}
 
-	if err = syscall.SetsockoptInt(fileDescriptor, syscall.SOL_IP, syscall.IP_RECVORIGDSTADDR, 1); err != nil {
-		return nil, &net.OpError{Op: "listen", Net: network, Source: nil, Addr: laddr, Err: fmt.Errorf("set socket option: IP_RECVORIGDSTADDR: %s", err)}
+	if laddr.IP == nil || laddr.IP.To4() != nil {
+		if err = syscall.SetsockoptInt(fileDescriptor, syscall.SOL_IP, syscall.IP_RECVORIGDSTADDR, 1); err != nil {
+			return nil, &net.OpError{Op: "listen", Net: network, Source: nil, Addr: laddr, Err: fmt.Errorf("set socket option: IP_RECVORIGDSTADDR: %s", err)}
+		}
+	}
+
+	if laddr.IP == nil || laddr.IP.To4() == nil {
+		if err = syscall.SetsockoptInt(fileDescriptor, syscall.SOL_IPV6, unix.IPV6_RECVORIGDSTADDR, 1); err != nil {
+			return nil, &net.OpError{Op: "listen", Net: network, Source: nil, Addr: laddr, Err: fmt.Errorf("set socket option: IPV6_RECVORIGDSTADDR: %s", err)}
+		}
 	}
 
 	return listener, nil
@@ -60,44 +65,20 @@ func ReadFromUDP(conn *net.UDPConn, b []byte) (int, *net.UDPAddr, *net.UDPAddr,
 		return 0, nil, nil, fmt.Errorf("parsing socket control message: %s", err)
 	}
 
-	var originalDst *net.UDPAddr
 	for _, msg := range msgs {
-		if (msg.Header.Level == syscall.SOL_IP || msg.Header.Level == syscall.SOL_IPV6) &&
-			msg.Header.Type == syscall.IP_RECVORIGDSTADDR {
-			originalDstRaw := &syscall.RawSockaddrInet4{}
-			if err = binary.Read(bytes.NewReader(msg.Data), binary.LittleEndian, originalDstRaw); err != nil {
-				return 0, nil, nil, fmt.Errorf("reading original destination address: %s", err)
-			}
-
-			switch originalDstRaw.Family {
-			case syscall.AF_INET:
-				pp := (*syscall.RawSockaddrInet4)(unsafe.Pointer(originalDstRaw))
-				p := (*[2]byte)(unsafe.Pointer(&pp.Port))
-				originalDst = &net.UDPAddr{
-					IP:   net.IPv4(pp.Addr[0], pp.Addr[1], pp.Addr[2], pp.Addr[3]),
-					Port: int(p[0])<<8 + int(p[1]),
-				}
-
-			case syscall.AF_INET6:
-				pp := (*syscall.RawSockaddrInet6)(unsafe.Pointer(originalDstRaw))
-				p := (*[2]byte)(unsafe.Pointer(&pp.Port))
-				originalDst = &net.UDPAddr{
-					IP:   net.IP(pp.Addr[:]),
-					Port: int(p[0])<<8 + int(p[1]),
-					Zone: strconv.Itoa(int(pp.Scope_id)),
-				}
-
-			default:
-				return 0, nil, nil, fmt.Errorf("original destination is an unsupported network family")
-			}
+		if msg.Header.Level == syscall.SOL_IP && msg.Header.Type == syscall.IP_RECVORIGDSTADDR {
+			ip := net.IP(msg.Data[4:8])
+			port := binary.BigEndian.Uint16(msg.Data[2:4])
+			return n, addr, &net.UDPAddr{IP: ip, Port: int(port)}, nil
+		}
+		if msg.Header.Level == syscall.SOL_IPV6 && msg.Header.Type == unix.IPV6_RECVORIGDSTADDR {
+			ip := net.IP(msg.Data[8:24])
+			port := binary.BigEndian.Uint16(msg.Data[2:4])
+			return n, addr, &net.UDPAddr{IP: ip, Port: int(port)}, nil
 		}
 	}
 
-	if originalDst == nil {
-		return 0, nil, nil, fmt.Errorf("unable to obtain original destination: %s", err)
-	}
-
-	return n, addr, originalDst, nil
+	return 0, nil, nil, fmt.Errorf("unable to obtain original destination: %s", err)
 }
 
 // ListenPacket acts like net.ListenPacket but the addr could be non-local.