fix netns for socks5 and relay handler

internal/net/net.go

@@ -1,8 +1,13 @@
 package net
 
 import (
+	"context"
+	"fmt"
 	"net"
+	"runtime"
 	"syscall"
+
+	"github.com/vishvananda/netns"
 )
 
 type SetBuffer interface {
@@ -26,3 +31,57 @@ type SetDSCP interface {
 func IsIPv4(address string) bool {
 	return address != "" && address[0] != ':' && address[0] != '['
 }
+
+type ListenConfig struct {
+	Netns string
+	net.ListenConfig
+}
+
+func (lc *ListenConfig) Listen(ctx context.Context, network, address string) (net.Listener, error) {
+	if lc.Netns != "" {
+		runtime.LockOSThread()
+		defer runtime.UnlockOSThread()
+
+		originNs, err := netns.Get()
+		if err != nil {
+			return nil, fmt.Errorf("netns.Get(): %v", err)
+		}
+		defer netns.Set(originNs)
+
+		ns, err := netns.GetFromName(lc.Netns)
+		if err != nil {
+			return nil, fmt.Errorf("netns.GetFromName(%s): %v", lc.Netns, err)
+		}
+		defer ns.Close()
+
+		if err := netns.Set(ns); err != nil {
+			return nil, fmt.Errorf("netns.Set(%s): %v", lc.Netns, err)
+		}
+	}
+
+	return lc.ListenConfig.Listen(ctx, network, address)
+}
+
+func (lc *ListenConfig) ListenPacket(ctx context.Context, network, address string) (net.PacketConn, error) {
+	if lc.Netns != "" {
+		runtime.LockOSThread()
+		defer runtime.UnlockOSThread()
+
+		originNs, err := netns.Get()
+		if err != nil {
+			return nil, fmt.Errorf("netns.Get(): %v", err)
+		}
+		defer netns.Set(originNs)
+
+		ns, err := netns.GetFromName(lc.Netns)
+		if err != nil {
+			return nil, fmt.Errorf("netns.GetFromName(%s): %v", lc.Netns, err)
+		}
+		defer ns.Close()
+
+		if err := netns.Set(ns); err != nil {
+			return nil, fmt.Errorf("netns.Set(%s): %v", lc.Netns, err)
+		}
+	}
+	return lc.ListenConfig.ListenPacket(ctx, network, address)
+}