fix: add ipv6 support

src/internal/netfilter/firewall.go

@@ -155,6 +155,16 @@ func (f *Firewall) AddTproxyRoute(fwmark, routeTable string) error {
 		return fmt.Errorf("cmd.Run: %w", err)
 	}
 
+	cmd = exec.Command("ip", "-6", "rule", "add", "fwmark", fwmark, "table", routeTable)
+	if err := cmd.Run(); err != nil {
+		slog.Warn("ip -6 rule add", slog.String("error", err.Error()))
+	}
+
+	cmd = exec.Command("ip", "-6", "route", "add", "local", "::/0", "dev", "lo", "table", routeTable)
+	if err := cmd.Run(); err != nil {
+		slog.Warn("ip -6 route add", slog.String("error", err.Error()))
+	}
+
 	return nil
 }
 
@@ -165,6 +175,12 @@ func (f *Firewall) DeleteTproxyRoute(fwmark, routeTable string) error {
 	cmd = exec.Command("ip", "route", "flush", "table", routeTable)
 	_ = cmd.Run()
 
+	cmd = exec.Command("ip", "-6", "rule", "del", "fwmark", fwmark, "table", routeTable)
+	_ = cmd.Run()
+
+	cmd = exec.Command("ip", "-6", "route", "flush", "table", routeTable)
+	_ = cmd.Run()
+
 	return nil
 }
 

src/internal/server/base/tcp_linux.go

@@ -3,10 +3,13 @@
 package base
 
 import (
+	"encoding/binary"
 	"errors"
 	"fmt"
+	"log/slog"
 	"net"
 	"syscall"
+	"unsafe"
 
 	"golang.org/x/sys/unix"
 )
@@ -37,18 +40,43 @@ func GetOriginalDstAddr(conn net.Conn) (addr string, err error) {
 		return "", errors.New("GetConnFD connection is not *net.TCPConn")
 	}
 
-	file, err := tcpConn.File()
+	rawConn, err := tcpConn.SyscallConn()
 	if err != nil {
-		return "", fmt.Errorf("tcpConn.File: %v", err)
-	}
-	defer file.Close()
-
-	raw, err := unix.GetsockoptIPv6Mreq(int(file.Fd()), unix.SOL_IP, unix.SO_ORIGINAL_DST)
-	if err != nil {
-		return "", fmt.Errorf("unix.GetsockoptIPv6Mreq: %v", err)
+		return "", fmt.Errorf("SyscallConn: %v", err)
 	}
 
-	ip := net.IPv4(raw.Multiaddr[4], raw.Multiaddr[5], raw.Multiaddr[6], raw.Multiaddr[7])
-	port := uint16(raw.Multiaddr[2])<<8 + uint16(raw.Multiaddr[3])
-	return fmt.Sprintf("%s:%d", ip.String(), port), nil
+	var originalAddr string
+	err = rawConn.Control(func(fd uintptr) {
+		level := syscall.IPPROTO_IP
+		if conn.RemoteAddr().String()[0] == '[' {
+			level = syscall.IPPROTO_IPV6
+		}
+
+		addr, err := syscall.GetsockoptIPv6MTUInfo(int(fd), level, unix.SO_ORIGINAL_DST)
+		if err != nil {
+			slog.Warn("unix.GetsockoptIPv6MTUInfo", "error", err)
+			return
+		}
+
+		var ip net.IP
+		if level == syscall.IPPROTO_IPV6 {
+			ip = net.IP(addr.Addr.Addr[:])
+		} else {
+			ipBytes := (*[4]byte)(unsafe.Pointer(&addr.Addr.Flowinfo))[:4]
+			ip = net.IPv4(ipBytes[0], ipBytes[1], ipBytes[2], ipBytes[3])
+		}
+
+		port := binary.BigEndian.Uint16((*[2]byte)(unsafe.Pointer(&addr.Addr.Port))[:2])
+
+		if level == syscall.IPPROTO_IPV6 {
+			originalAddr = fmt.Sprintf("[%s]:%d", ip.String(), port)
+		} else {
+			originalAddr = fmt.Sprintf("%s:%d", ip.String(), port)
+		}
+	})
+	if err != nil {
+		return "", fmt.Errorf("rawConn.Control: %v", err)
+	}
+
+	return originalAddr, nil
 }

src/internal/server/tproxy/nftables.go

@@ -96,6 +96,16 @@ func (s *Server) NftSetTproxy(tx *knftables.Transaction, table *knftables.Table)
 				"counter accept",
 			),
 		})
+		tx.Add(&knftables.Rule{
+			Chain: sidecar.Name,
+			Rule: knftables.Concat(
+				"meta l4proto tcp",
+				"mark", s.tproxyFwMark,
+				"mark set 7894",
+				fmt.Sprintf("tproxy ip6 to [::1]:%d", s.Cfg.Port),
+				"counter accept",
+			),
+		})
 	}
 
 	prerouting := &knftables.Chain{
@@ -175,6 +185,15 @@ func (s *Server) NftSetTproxy(tx *knftables.Transaction, table *knftables.Table)
 			"counter accept",
 		),
 	})
+	tx.Add(&knftables.Rule{
+		Chain: prerouting.Name,
+		Rule: knftables.Concat(
+			"meta l4proto tcp",
+			"mark", s.tproxyFwMark,
+			fmt.Sprintf("tproxy ip6 to [::1]:%d", s.Cfg.Port),
+			"counter accept",
+		),
+	})
 
 	// default less hit. sc.
 	tx.Add(&knftables.Rule{
@@ -186,6 +205,15 @@ func (s *Server) NftSetTproxy(tx *knftables.Transaction, table *knftables.Table)
 			"counter accept",
 		),
 	})
+	tx.Add(&knftables.Rule{
+		Chain: prerouting.Name,
+		Rule: knftables.Concat(
+			"meta l4proto tcp",
+			"mark set", s.tproxyFwMark,
+			fmt.Sprintf("tproxy ip6 to [::1]:%d", s.Cfg.Port),
+			"counter accept",
+		),
+	})
 
 	output := &knftables.Chain{
 		Name:     "OUTPUT",