[feat] listen on available port

cmd/bitmask-helper/main.go

@@ -24,8 +24,8 @@ import (
 )
 
 const (
-	bindAddr = "localhost:7171"
-	logFile  = "helper.log"
+	preferredPort = 7171
+	logFile       = "helper.log"
 )
 
 func main() {
@@ -36,6 +36,5 @@ func main() {
 		defer logger.Close()
 	}
 
-	helper.ServeHTTP(bindAddr)
-
+	helper.ServeHTTP(preferredPort)
 }

pkg/helper/darwin.go

@@ -33,6 +33,7 @@ import (
 	"os"
 	"os/exec"
 	"path"
+	"strconv"
 	"strings"
 
 	"0xacab.org/leap/bitmask-vpn/pkg/config"
@@ -86,8 +87,8 @@ func daemonize() {
 	log.Print("bitmask-helper daemon started")
 }
 
-func doHandleCommands(bindAddr string) {
-	runCommandServer(bindAddr)
+func doHandleCommands(port int) {
+	runCommandServer("localhost:" + strconv.Itoa(port))
 }
 
 func getOpenvpnPath() string {

pkg/helper/helper.go

@@ -37,10 +37,10 @@ func runCommandServer(bindAddr string) {
 	log.Fatal(http.ListenAndServe(bindAddr, nil))
 }
 
-func ServeHTTP(bindAddr string) {
+func ServeHTTP(port int) {
 	parseCliArgs()
 	daemonize()
-	doHandleCommands(bindAddr)
+	doHandleCommands(port)
 }
 
 func (openvpn *openvpnT) start(w http.ResponseWriter, r *http.Request) {

pkg/helper/linux.go

@@ -20,6 +20,7 @@ import (
 	"log"
 	"os"
 	"os/exec"
+	"strconv"
 
 	"0xacab.org/leap/bitmask-vpn/pkg/config"
 )
@@ -46,8 +47,8 @@ func parseCliArgs() {
 
 func daemonize() {}
 
-func doHandleCommands(bindAddr string) {
-	runCommandServer(bindAddr)
+func doHandleCommands(port int) {
+	runCommandServer("localhost:" + strconv.Itoa(port))
 }
 
 func getOpenvpnPath() string {

pkg/helper/ports.go

+package helper
+
+import (
+	"io/ioutil"
+	"net"
+	"os"
+	"path"
+	"strconv"
+)
+
+func getFirstAvailablePortFrom(port int) int {
+	for {
+		if isPortAvailable(port) {
+			return port
+		}
+		if port > 65535 {
+			return 0
+		}
+		port += 1
+	}
+}
+
+func isPortAvailable(port int) bool {
+	conn, err := net.Dial("tcp", "127.0.0.1:"+strconv.Itoa(port))
+	if err != nil {
+		return true
+	} else {
+		defer conn.Close()
+		return false
+	}
+}
+
+func writePortToFile(port int) error {
+	exeDir, err := getExecutableDir()
+	if err != nil {
+		return err
+	}
+	portFile := path.Join(exeDir, "port")
+	return ioutil.WriteFile(portFile, []byte(strconv.Itoa(port)+"\n"), 0644)
+
+}
+
+func getExecutableDir() (string, error) {
+	ex, err := os.Executable()
+	if err != nil {
+		return "", err
+	}
+	return path.Dir(ex), nil
+}

pkg/helper/windows.go

@@ -21,6 +21,7 @@ import (
 	"log"
 	"os"
 	"os/exec"
+	"strconv"
 	"strings"
 
 	"0xacab.org/leap/bitmask-vpn/pkg/config"
@@ -97,7 +98,10 @@ func usage(errmsg string) {
 func daemonize() {}
 
 // http server is called from within Execute in windows
-func doHandleCommands(bindAddr string) {
+func doHandleCommands(preferredPort int) {
+	port := getFirstAvailablePortFrom(preferredPort)
+	writePortToFile(port)
+	bindAddr := "localhost:" + strconv.Itoa(port)
 	httpBindAddr = bindAddr
 }
 

pkg/helper/windows_service.go

@@ -8,8 +8,6 @@ package helper
 
 import (
 	"fmt"
-	//"strings"
-	//"time"
 
 	"golang.org/x/sys/windows/svc"
 	"golang.org/x/sys/windows/svc/debug"
@@ -24,8 +22,7 @@ func (m *myservice) Execute(args []string, r <-chan svc.ChangeRequest, changes c
 	const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown | svc.AcceptPauseAndContinue
 	changes <- svc.Status{State: svc.StartPending}
 	changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
-	// TODO use httpBindAddr
-	go runCommandServer("localhost:7171")
+	go runCommandServer(httpBindAddr)
 loop:
 	for {
 		select {