add support for linux network namespace

chain/route.go

@@ -38,6 +38,7 @@ func (*route) Dial(ctx context.Context, network, address string, opts ...DialOpt
 	netd := dialer.NetDialer{
 		Timeout:   options.Timeout,
 		Interface: options.Interface,
+		Netns:     options.Netns,
 		Logger:    options.Logger,
 	}
 	if options.SockOpts != nil {
@@ -95,6 +96,7 @@ func (r *route) Nodes() []*Node {
 type DialOptions struct {
 	Timeout   time.Duration
 	Interface string
+	Netns     string
 	SockOpts  *SockOpts
 	Logger    logger.Logger
 }
@@ -113,6 +115,12 @@ func InterfaceDialOption(ifName string) DialOption {
 	}
 }
 
+func NetnsDialOption(netns string) DialOption {
+	return func(opts *DialOptions) {
+		opts.Netns = netns
+	}
+}
+
 func SockOptsDialOption(so *SockOpts) DialOption {
 	return func(opts *DialOptions) {
 		opts.SockOpts = so

chain/router.go

@@ -21,6 +21,7 @@ type RouterOptions struct {
 	Retries    int
 	Timeout    time.Duration
 	IfceName   string
+	Netns      string
 	SockOpts   *SockOpts
 	Chain      Chainer
 	Resolver   resolver.Resolver
@@ -37,6 +38,12 @@ func InterfaceRouterOption(ifceName string) RouterOption {
 	}
 }
 
+func NetnsRouterOption(netns string) RouterOption {
+	return func(o *RouterOptions) {
+		o.Netns = netns
+	}
+}
+
 func SockOptsRouterOption(so *SockOpts) RouterOption {
 	return func(o *RouterOptions) {
 		o.SockOpts = so
@@ -181,6 +188,7 @@ func (r *Router) dial(ctx context.Context, network, address string) (conn net.Co
 		}
 		conn, err = route.Dial(ctx, network, ipAddr,
 			InterfaceDialOption(r.options.IfceName),
+			NetnsDialOption(r.options.Netns),
 			SockOptsDialOption(r.options.SockOpts),
 			LoggerDialOption(r.options.Logger),
 			TimeoutDialOption(r.options.Timeout),

chain/transport.go

@@ -13,6 +13,7 @@ import (
 type TransportOptions struct {
 	Addr     string
 	IfceName string
+	Netns    string
 	SockOpts *SockOpts
 	Route    Route
 	Timeout  time.Duration
@@ -32,6 +33,12 @@ func InterfaceTransportOption(ifceName string) TransportOption {
 	}
 }
 
+func NetnsTransportOption(netns string) TransportOption {
+	return func(o *TransportOptions) {
+		o.Netns = netns
+	}
+}
+
 func SockOptsTransportOption(so *SockOpts) TransportOption {
 	return func(o *TransportOptions) {
 		o.SockOpts = so
@@ -73,6 +80,7 @@ func NewTransport(d dialer.Dialer, c connector.Connector, opts ...TransportOptio
 func (tr *Transport) Dial(ctx context.Context, addr string) (net.Conn, error) {
 	netd := &net_dialer.NetDialer{
 		Interface: tr.options.IfceName,
+		Netns:     tr.options.Netns,
 		Timeout:   tr.options.Timeout,
 	}
 	if tr.options.SockOpts != nil {
@@ -108,6 +116,7 @@ func (tr *Transport) Handshake(ctx context.Context, conn net.Conn) (net.Conn, er
 func (tr *Transport) Connect(ctx context.Context, conn net.Conn, network, address string) (net.Conn, error) {
 	netd := &net_dialer.NetDialer{
 		Interface: tr.options.IfceName,
+		Netns:     tr.options.Netns,
 		Timeout:   tr.options.Timeout,
 	}
 	if tr.options.SockOpts != nil {

common/net/dialer/dialer.go

@@ -4,12 +4,14 @@ import (
 	"context"
 	"fmt"
 	"net"
+	"runtime"
 	"strings"
 	"syscall"
 	"time"
 
 	xnet "github.com/go-gost/core/common/net"
 	"github.com/go-gost/core/logger"
+	"github.com/vishvananda/netns"
 )
 
 const (
@@ -22,6 +24,7 @@ var (
 
 type NetDialer struct {
 	Interface string
+	Netns     string
 	Mark      int
 	Timeout   time.Duration
 	DialFunc  func(ctx context.Context, network, addr string) (net.Conn, error)
@@ -33,6 +36,32 @@ func (d *NetDialer) Dial(ctx context.Context, network, addr string) (conn net.Co
 		d = DefaultNetDialer
 	}
 
+	log := d.Logger
+	if log == nil {
+		log = logger.Default()
+	}
+
+	if d.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(d.Netns)
+		if err != nil {
+			return nil, fmt.Errorf("netns.GetFromName(%s): %v", d.Netns, err)
+		}
+		defer ns.Close()
+
+		if err := netns.Set(ns); err != nil {
+			return nil, fmt.Errorf("netns.Set(%s): %v", d.Netns, err)
+		}
+	}
+
 	timeout := d.Timeout
 	if timeout <= 0 {
 		timeout = DefaultTimeout
@@ -42,11 +71,6 @@ func (d *NetDialer) Dial(ctx context.Context, network, addr string) (conn net.Co
 		return d.DialFunc(ctx, network, addr)
 	}
 
-	log := d.Logger
-	if log == nil {
-		log = logger.Default()
-	}
-
 	switch network {
 	case "unix":
 		netd := net.Dialer{}
@@ -150,5 +174,10 @@ func (d *NetDialer) dialOnce(ctx context.Context, network, addr, ifceName string
 			})
 		},
 	}
+	if d.Netns != "" {
+		// https://github.com/golang/go/issues/44922#issuecomment-796645858
+		netd.FallbackDelay = -1
+	}
+
 	return netd.DialContext(ctx, network, addr)
 }

go.mod

@@ -6,5 +6,6 @@ toolchain go1.22.2
 
 require (
 	github.com/go-gost/x v0.0.0-20240131151842-25dcf536c6f5
-	golang.org/x/sys v0.18.0
+	github.com/vishvananda/netns v0.0.4
+	golang.org/x/sys v0.21.0
 )

go.sum

@@ -1,4 +1,6 @@
 github.com/go-gost/x v0.0.0-20240131151842-25dcf536c6f5 h1:IiZLdqGMx0lGVbDBy/N9LPu10qSlxm939EBvZ77qJNI=
 github.com/go-gost/x v0.0.0-20240131151842-25dcf536c6f5/go.mod h1:FDqjiiPbCqJLU/wY+q2IZCBVcYnfTJTw+SJLrspLQms=
-golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
+github.com/vishvananda/netns v0.0.4 h1:Oeaw1EM2JMxD51g9uhtC0D7erkIjgmj8+JZc26m1YX8=
-golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+github.com/vishvananda/netns v0.0.4/go.mod h1:SpkAiCQRtJ6TvvxPnOSyH3BMl6unz3xZlaprSwhNNJM=
+golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
+golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=