Moved TUN device creation to pre-fork

src/daemon_linux.go

@@ -11,18 +11,9 @@ import (
  * TODO: Use env variable to spawn in background
  */
 
-func Daemonize() error {
+func Daemonize(attr *os.ProcAttr) error {
 	argv := []string{os.Args[0], "--foreground"}
 	argv = append(argv, os.Args[1:]...)
-	attr := &os.ProcAttr{
-		Dir: ".",
-		Env: os.Environ(),
-		Files: []*os.File{
-			os.Stdin,
-			nil,
-			nil,
-		},
-	}
 	process, err := os.StartProcess(
 		argv[0],
 		argv,

src/device.go

@@ -126,13 +126,13 @@ func (device *Device) PutMessageBuffer(msg *[MaxMessageSize]byte) {
 	device.pool.messageBuffers.Put(msg)
 }
 
-func NewDevice(tun TUNDevice, logLevel int) *Device {
+func NewDevice(tun TUNDevice, logger *Logger) *Device {
 	device := new(Device)
 
 	device.mutex.Lock()
 	defer device.mutex.Unlock()
 
-	device.log = NewLogger(logLevel, "("+tun.Name()+") ")
+	device.log = logger
 	device.peers = make(map[NoisePublicKey]*Peer)
 	device.tun.device = tun
 

src/main.go

@@ -2,10 +2,14 @@ package main
 
 import (
 	"fmt"
-	"log"
 	"os"
 	"os/signal"
 	"runtime"
+	"strconv"
+)
+
+const (
+	EnvWGTunFD = "WG_TUN_FD"
 )
 
 func printUsage() {
@@ -43,28 +47,6 @@ func main() {
 		interfaceName = os.Args[1]
 	}
 
-	// daemonize the process
-
-	if !foreground {
-		err := Daemonize()
-		if err != nil {
-			log.Println("Failed to daemonize:", err)
-		}
-		return
-	}
-
-	// increase number of go workers (for Go <1.5)
-
-	runtime.GOMAXPROCS(runtime.NumCPU())
-
-	// open TUN device
-
-	tun, err := CreateTUN(interfaceName)
-	if err != nil {
-		log.Println("Failed to create tun device:", err)
-		return
-	}
-
 	// get log level (default: info)
 
 	logLevel := func() int {
@@ -79,22 +61,76 @@ func main() {
 		return LogLevelInfo
 	}()
 
+	logger := NewLogger(
+		logLevel,
+		fmt.Sprintf("(%s) ", interfaceName),
+	)
+	logger.Debug.Println("Debug log enabled")
+
+	// open TUN device
+
+	tun, err := func() (TUNDevice, error) {
+		tunFdStr := os.Getenv(EnvWGTunFD)
+		if tunFdStr == "" {
+			return CreateTUN(interfaceName)
+		}
+
+		// construct tun device from supplied FD
+
+		fd, err := strconv.ParseUint(tunFdStr, 10, 32)
+		if err != nil {
+			return nil, err
+		}
+
+		file := os.NewFile(uintptr(fd), "/dev/net/tun")
+		return CreateTUNFromFile(interfaceName, file)
+	}()
+
+	if err != nil {
+		logger.Error.Println("Failed to create TUN device:", err)
+	}
+
+	// daemonize the process
+
+	if !foreground {
+		env := os.Environ()
+		_, ok := os.LookupEnv(EnvWGTunFD)
+		if !ok {
+			kvp := fmt.Sprintf("%s=3", EnvWGTunFD)
+			env = append(env, kvp)
+		}
+		attr := &os.ProcAttr{
+			Files: []*os.File{
+				nil, // stdin
+				nil, // stdout
+				nil, // stderr
+				tun.File(),
+			},
+			Dir: ".",
+			Env: env,
+		}
+		err = Daemonize(attr)
+		if err != nil {
+			logger.Error.Println("Failed to daemonize:", err)
+		}
+		return
+	}
+
+	// increase number of go workers (for Go <1.5)
+
+	runtime.GOMAXPROCS(runtime.NumCPU())
+
 	// create wireguard device
 
-	device := NewDevice(tun, logLevel)
-
-	logInfo := device.log.Info
-	logError := device.log.Error
-	logDebug := device.log.Debug
-
-	logInfo.Println("Device started")
-	logDebug.Println("Debug log enabled")
+	device := NewDevice(tun, logger)
+	logger.Info.Println("Device started")
 
 	// start configuration lister
 
 	uapi, err := NewUAPIListener(interfaceName)
 	if err != nil {
-		logError.Fatal("UAPI listen error:", err)
+		logger.Error.Println("UAPI listen error:", err)
+		return
 	}
 
 	errs := make(chan error)
@@ -112,7 +148,7 @@ func main() {
 		}
 	}()
 
-	logInfo.Println("UAPI listener started")
+	logger.Info.Println("UAPI listener started")
 
 	// wait for program to terminate
 
@@ -129,5 +165,5 @@ func main() {
 
 	uapi.Close()
 
-	logInfo.Println("Closing")
+	logger.Info.Println("Shutting down")
 }

src/tests/netns.sh

@@ -28,7 +28,7 @@ netns0="wg-test-$$-0"
 netns1="wg-test-$$-1"
 netns2="wg-test-$$-2"
 program="../wireguard-go"
-export LOG_LEVEL="debug"
+export LOG_LEVEL="info"
 
 pretty() { echo -e "\x1b[32m\x1b[1m[+] ${1:+NS$1: }${2}\x1b[0m" >&3; }
 pp() { pretty "" "$*"; "$@"; }
@@ -72,13 +72,11 @@ pp ip netns add $netns2
 ip0 link set up dev lo
 
 # ip0 link add dev wg1 type wireguard
-n0 $program -f wg1 &
-sleep 1
+n0 $program wg1
 ip0 link set wg1 netns $netns1
 
 # ip0 link add dev wg1 type wireguard
-n0 $program -f wg2 &
-sleep 1
+n0 $program wg2
 ip0 link set wg2 netns $netns2
 
 key1="$(pp wg genkey)"
@@ -147,8 +145,6 @@ tests() {
     n1 iperf3 -Z -n 1G -b 0 -u -c fd00::2
 }
 
-echo "4"
-
 [[ $(ip1 link show dev wg1) =~ mtu\ ([0-9]+) ]] && orig_mtu="${BASH_REMATCH[1]}"
 big_mtu=$(( 34816 - 1500 + $orig_mtu ))
 
@@ -234,9 +230,8 @@ ip2 link del wg2
 # ip1 link add dev wg1 type wireguard
 # ip2 link add dev wg1 type wireguard
 
-n1 $program -f wg1 &
-n2 $program -f wg2 &
-sleep 5
+n1 $program wg1
+n2 $program wg2
 
 configure_peers
 
@@ -291,9 +286,8 @@ ip2 link del wg2
 
 # ip1 link add dev wg1 type wireguard
 # ip2 link add dev wg1 type wireguard
-n1 $program -f wg1 &
-n2 $program -f wg2 &
-sleep 5
+n1 $program wg1
+n2 $program wg2
 
 configure_peers
 
@@ -354,4 +348,5 @@ n2 ping -W 1 -c 1 192.168.241.1
 ip1 link del veth1
 ip1 link del wg1
 ip2 link del wg2
+
 echo "done"

src/tun.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"sync/atomic"
 )
 
@@ -15,6 +16,7 @@ const (
 )
 
 type TUNDevice interface {
+	File() *os.File            // returns the file descriptor of the device
 	Read([]byte) (int, error)  // read a packet from the device (without any additional headers)
 	Write([]byte) (int, error) // writes a packet to the device (without any additional headers)
 	MTU() (int, error)         // returns the MTU of the device

src/tun_linux.go

@@ -56,6 +56,11 @@ type NativeTun struct {
 	events chan TUNEvent // device related events
 }
 
+func (tun *NativeTun) File() *os.File {
+	println(tun.fd.Name())
+	return tun.fd
+}
+
 func (tun *NativeTun) RoutineNetlinkListener() {
 	sock := int(C.bind_rtmgrp())
 	if sock < 0 {
@@ -248,6 +253,29 @@ func (tun *NativeTun) Close() error {
 	return nil
 }
 
+func CreateTUNFromFile(name string, fd *os.File) (TUNDevice, error) {
+	device := &NativeTun{
+		fd:     fd,
+		name:   name,
+		events: make(chan TUNEvent, 5),
+		errors: make(chan error, 5),
+	}
+
+	// start event listener
+
+	var err error
+	device.index, err = getIFIndex(device.name)
+	if err != nil {
+		return nil, err
+	}
+
+	go device.RoutineNetlinkListener()
+
+	// set default MTU
+
+	return device, device.setMTU(DefaultMTU)
+}
+
 func CreateTUN(name string) (TUNDevice, error) {
 
 	// open clone device