From b21c82e32d955e15d846aed87535b6d728ab1d0b Mon Sep 17 00:00:00 2001
From: Mathias Hall-Andersen <mathias@hall-andersen.dk>
Date: Sat, 15 Jul 2017 13:41:02 +0200
Subject: [PATCH] Conforming to the cross-platform UX

The implementation now terminates when the unix socket is deleted.
Currently we are unable to use fsnotify (on linux),
since it does not notify on the deletion of open files.

The implementation can now daemonize (on linux)
or be kept in the foreground by providing the necessary flag.
---
 src/daemon_linux.go | 34 +++++++++++++++++++
 src/main.go         | 73 +++++++++++++++++++++++++--------------
 src/uapi_linux.go   | 83 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 165 insertions(+), 25 deletions(-)
 create mode 100644 src/daemon_linux.go
 create mode 100644 src/uapi_linux.go

diff --git a/src/daemon_linux.go b/src/daemon_linux.go
new file mode 100644
index 0000000..809c176
--- /dev/null
+++ b/src/daemon_linux.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"os"
+)
+
+/* Daemonizes the process on linux
+ *
+ * This is done by spawning and releasing a copy with the --foreground flag
+ */
+
+func Daemonize() 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,
+		attr,
+	)
+	if err != nil {
+		return err
+	}
+	process.Release()
+	return nil
+}
diff --git a/src/main.go b/src/main.go
index dc27472..74e7ec9 100644
--- a/src/main.go
+++ b/src/main.go
@@ -1,23 +1,45 @@
 package main
 
 import (
-	"fmt"
 	"log"
-	"net"
 	"os"
 	"runtime"
 )
 
-/* TODO: Fix logging
- * TODO: Fix daemon
- */
-
 func main() {
 
-	if len(os.Args) != 2 {
+	// parse arguments
+
+	var foreground bool
+	var interfaceName string
+	if len(os.Args) < 2 || len(os.Args) > 3 {
+		return
+	}
+
+	switch os.Args[1] {
+	case "-f", "--foreground":
+		foreground = true
+		if len(os.Args) != 3 {
+			return
+		}
+		interfaceName = os.Args[2]
+	default:
+		foreground = false
+		if len(os.Args) != 2 {
+			return
+		}
+		interfaceName = os.Args[1]
+	}
+
+	// daemonize the process
+
+	if !foreground {
+		err := Daemonize()
+		if err != nil {
+			log.Println("Failed to daemonize:", err)
+		}
 		return
 	}
-	deviceName := os.Args[1]
 
 	// increase number of go workers (for Go <1.5)
 
@@ -25,32 +47,33 @@ func main() {
 
 	// open TUN device
 
-	tun, err := CreateTUN(deviceName)
+	tun, err := CreateTUN(interfaceName)
 	log.Println(tun, err)
 	if err != nil {
 		return
 	}
 
+	// create wireguard device
+
 	device := NewDevice(tun, LogLevelDebug)
-	device.log.Info.Println("Starting device")
+
+	logInfo := device.log.Info
+	logError := device.log.Error
+	logInfo.Println("Starting device")
 
 	// start configuration lister
 
-	go func() {
-		socketPath := fmt.Sprintf("/var/run/wireguard/%s.sock", deviceName)
-		l, err := net.Listen("unix", socketPath)
+	uapi, err := NewUAPIListener(interfaceName)
+	if err != nil {
+		logError.Fatal("UAPI listen error:", err)
+	}
+	defer uapi.Close()
+
+	for {
+		conn, err := uapi.Accept()
 		if err != nil {
-			log.Fatal("listen error:", err)
+			logError.Fatal("accept error:", err)
 		}
-
-		for {
-			conn, err := l.Accept()
-			if err != nil {
-				log.Fatal("accept error:", err)
-			}
-			go ipcHandle(device, conn)
-		}
-	}()
-
-	device.Wait()
+		go ipcHandle(device, conn)
+	}
 }
diff --git a/src/uapi_linux.go b/src/uapi_linux.go
new file mode 100644
index 0000000..ee6ee0b
--- /dev/null
+++ b/src/uapi_linux.go
@@ -0,0 +1,83 @@
+package main
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"time"
+)
+
+/* TODO:
+ * This code can be improved by using fsnotify once:
+ * https://github.com/fsnotify/fsnotify/pull/205
+ * Is merged
+ */
+
+type UAPIListener struct {
+	listener net.Listener // unix socket listener
+	connNew  chan net.Conn
+	connErr  chan error
+}
+
+func (l *UAPIListener) Accept() (net.Conn, error) {
+	for {
+		select {
+		case conn := <-l.connNew:
+			return conn, nil
+
+		case err := <-l.connErr:
+			return nil, err
+		}
+	}
+}
+
+func (l *UAPIListener) Close() error {
+	return l.listener.Close()
+}
+
+func (l *UAPIListener) Addr() net.Addr {
+	return nil
+}
+
+func NewUAPIListener(name string) (net.Listener, error) {
+
+	// open UNIX socket
+
+	socketPath := fmt.Sprintf("/var/run/wireguard/%s.sock", name)
+	listener, err := net.Listen("unix", socketPath)
+	if err != nil {
+		return nil, err
+	}
+
+	uapi := &UAPIListener{
+		listener: listener,
+		connNew:  make(chan net.Conn, 1),
+		connErr:  make(chan error, 1),
+	}
+
+	// watch for deletion of socket
+
+	go func(l *UAPIListener) {
+		for ; ; time.Sleep(time.Second) {
+			if _, err := os.Stat(socketPath); os.IsNotExist(err) {
+				l.connErr <- err
+				return
+			}
+		}
+	}(uapi)
+
+	// watch for new connections
+
+	go func(l *UAPIListener) {
+		for {
+			conn, err := l.listener.Accept()
+			if err != nil {
+				l.connErr <- err
+				break
+			}
+			l.connNew <- conn
+		}
+	}(uapi)
+
+	return uapi, nil
+}