f-8: code: use local usage of netns #8

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

go.mod

@@ -1,6 +1,8 @@
 module git.g3e.fr/syonad/two
 
-go 1.23.8
+go 1.24.0
+
+toolchain go1.24.11
 
 require (
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
@@ -29,7 +31,7 @@ require (
 	go.opentelemetry.io/otel/trace v1.37.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/net v0.41.0 // indirect
-	golang.org/x/sys v0.34.0 // indirect
+	golang.org/x/sys v0.39.0 // indirect
 	golang.org/x/text v0.28.0 // indirect
 	google.golang.org/protobuf v1.36.6 // indirect
 )

go.sum

@@ -53,6 +53,8 @@ golang.org/x/net v0.41.0 h1:vBTly1HeNPEn3wtREYfy4GZ/NECgw2Cnl+nK6Nz3uvw=
 golang.org/x/net v0.41.0/go.mod h1:B/K4NNqkfmg07DQYrbwvSluqCJOOXwUjeb/5lOisjbA=
 golang.org/x/sys v0.34.0 h1:H5Y5sJ2L2JRdyv7ROF1he/lPdvFsd0mJHFw2ThKHxLA=
 golang.org/x/sys v0.34.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
+golang.org/x/sys v0.39.0 h1:CvCKL8MeisomCi6qNZ+wbb0DN9E5AATixKsvNtMoMFk=
+golang.org/x/sys v0.39.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
 golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
 google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=

internal/metadata/server.go

@@ -9,14 +9,17 @@ import (
 	"net"
 	"net/http"
 	"time"
+
+	"git.g3e.fr/syonad/two/internal/netns"
 )
 
 var data NoCloudData
 
 var (
-	iface = flag.String("interface", "0.0.0.0", "Interface IP à écouter")
-	port  = flag.Int("port", 8080, "Port à utiliser")
-	file  = flag.String("file", "", "Fichier JSON contenant les données NoCloud")
+	iface      = flag.String("interface", "0.0.0.0", "Interface IP à écouter")
+	port       = flag.Int("port", 8080, "Port à utiliser")
+	file       = flag.String("file", "", "Fichier JSON contenant les données NoCloud")
+	netns_name = flag.String("netns", "", "Network namespace à utiliser")
 )
 
 func getIP(r *http.Request) string {
@@ -54,6 +57,12 @@ func rootHandler(w http.ResponseWriter, r *http.Request) {
 func StartServer() {
 	flag.Parse()
 
+	if *netns_name != "" {
+		if err := netns.Enter(*netns_name); err != nil {
+			log.Fatalf("Impossible d'entrer dans le netns: %v", err)
+		}
+	}
+
 	if *file == "" {
 		log.Fatal("Vous devez spécifier un fichier via --file")
 	}

internal/netns/enter.go

@@ -0,0 +1,5 @@
+package netns
+
+func Enter(name string) error {
+	return enter(name)
+}

internal/netns/enter_linux.go

@@ -0,0 +1,26 @@
+//go:build linux
+
+package netns
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+
+	"golang.org/x/sys/unix"
+)
+
+func enter(name string) error {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	path := fmt.Sprintf("/var/run/netns/%s", name)
+
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return unix.Setns(int(f.Fd()), unix.CLONE_NEWNET)
+}

internal/netns/enter_other.go

@@ -0,0 +1,8 @@
+//go:build !linux
+
+package netns
+
+func enter(name string) error {
+	// Ignoré hors Linux
+	return nil
+}