add support for linux network namespace

config/parsing/hop/parse.go

@@ -8,7 +8,9 @@ import (
 	"github.com/go-gost/core/chain"
 	"github.com/go-gost/core/hop"
 	"github.com/go-gost/core/logger"
+	mdutil "github.com/go-gost/core/metadata/util"
 	"github.com/go-gost/x/config"
+	"github.com/go-gost/x/config/parsing"
 	bypass_parser "github.com/go-gost/x/config/parsing/bypass"
 	node_parser "github.com/go-gost/x/config/parsing/node"
 	selector_parser "github.com/go-gost/x/config/parsing/selector"
@@ -16,6 +18,7 @@ import (
 	hop_plugin "github.com/go-gost/x/hop/plugin"
 	"github.com/go-gost/x/internal/loader"
 	"github.com/go-gost/x/internal/plugin"
+	"github.com/go-gost/x/metadata"
 )
 
 func ParseHop(cfg *config.HopConfig, log logger.Logger) (hop.Hop, error) {
@@ -47,6 +50,16 @@ func ParseHop(cfg *config.HopConfig, log logger.Logger) (hop.Hop, error) {
 		}
 	}
 
+	ifce := cfg.Interface
+	var netns string
+	if cfg.Metadata != nil {
+		md := metadata.NewMetadata(cfg.Metadata)
+		if v := mdutil.GetString(md, parsing.MDKeyInterface); v != "" {
+			ifce = v
+		}
+		netns = mdutil.GetString(md, "netns")
+	}
+
 	var nodes []*chain.Node
 	for _, v := range cfg.Nodes {
 		if v == nil {
@@ -60,8 +73,12 @@ func ParseHop(cfg *config.HopConfig, log logger.Logger) (hop.Hop, error) {
 			v.Hosts = cfg.Hosts
 		}
 		if v.Interface == "" {
-			v.Interface = cfg.Interface
+			v.Interface = ifce
 		}
+		if v.Netns == "" {
+			v.Netns = netns
+		}
+
 		if v.SockOpts == nil {
 			v.SockOpts = cfg.SockOpts
 		}

config/parsing/node/parse.go

@@ -143,6 +143,7 @@ func ParseNode(hop string, cfg *config.NodeConfig, log logger.Logger) (*chain.No
 	tr := chain.NewTransport(d, cr,
 		chain.AddrTransportOption(cfg.Addr),
 		chain.InterfaceTransportOption(cfg.Interface),
+		chain.NetnsTransportOption(cfg.Netns),
 		chain.SockOptsTransportOption(sockOpts),
 		chain.TimeoutTransportOption(10*time.Second),
 	)

config/parsing/service/parse.go

@@ -2,6 +2,7 @@ package service
 
 import (
 	"fmt"
+	"runtime"
 	"strings"
 	"time"
 
@@ -32,6 +33,7 @@ import (
 	"github.com/go-gost/x/registry"
 	xservice "github.com/go-gost/x/service"
 	"github.com/go-gost/x/stats"
+	"github.com/vishvananda/netns"
 )
 
 func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
@@ -104,6 +106,7 @@ func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
 	var ignoreChain bool
 	var pStats *stats.Stats
 	var observePeriod time.Duration
+	var netnsIn, netnsOut string
 	if cfg.Metadata != nil {
 		md := metadata.NewMetadata(cfg.Metadata)
 		ppv = mdutil.GetInt(md, parsing.MDKeyProxyProtocol)
@@ -125,6 +128,8 @@ func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
 			pStats = &stats.Stats{}
 		}
 		observePeriod = mdutil.GetDuration(md, "observePeriod")
+		netnsIn = mdutil.GetString(md, "netns")
+		netnsOut = mdutil.GetString(md, "netns.out")
 	}
 
 	listenOpts := []listener.Option{
@@ -146,6 +151,27 @@ func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
 		)
 	}
 
+	if netnsIn != "" {
+		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(netnsIn)
+		if err != nil {
+			return nil, fmt.Errorf("netns.GetFromName(%s): %v", netnsIn, err)
+		}
+		defer ns.Close()
+
+		if err := netns.Set(ns); err != nil {
+			return nil, fmt.Errorf("netns.Set(%s): %v", netnsIn, err)
+		}
+	}
+
 	var ln listener.Listener
 	if rf := registry.ListenerRegistry().Get(cfg.Listener.Type); rf != nil {
 		ln = rf(listenOpts...)
@@ -209,6 +235,7 @@ func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
 		chain.RetriesRouterOption(cfg.Handler.Retries),
 		// chain.TimeoutRouterOption(10*time.Second),
 		chain.InterfaceRouterOption(ifce),
+		chain.NetnsRouterOption(netnsOut),
 		chain.SockOptsRouterOption(sockOpts),
 		chain.ResolverRouterOption(registry.ResolverRegistry().Get(cfg.Resolver)),
 		chain.HostMapperRouterOption(registry.HostsRegistry().Get(cfg.Hosts)),