Add restart endpoint

Former-commit-id: 734542c3ed

main.go

@@ -1032,6 +1032,19 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 		logger.Info("Tunnel destroyed, ready for reconnection")
 	})
 
+	client.RegisterHandler("newt/wg/restart", func(msg websocket.WSMessage) {
+		closeWgTunnel()
+		closeClients()
+		if healthMonitor != nil {
+			healthMonitor.Stop()
+		}
+		client.Close()
+		if err := reexec(); err != nil {
+			logger.Error("Failed to restart: %v", err)
+			os.Exit(1)
+		}
+	})
+
 	client.RegisterHandler("newt/wg/terminate", func(msg websocket.WSMessage) {
 		logger.Info("Received termination message")
 		if wgData.PublicKey != "" {
@@ -1968,13 +1981,8 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 						healthMonitor.Stop()
 					}
 					client.Close()
-					exe, exeErr := os.Executable()
-					if exeErr != nil {
-						logger.Error("Failed to get executable path for restart: %v", exeErr)
-						os.Exit(0)
-					}
-					if err := syscall.Exec(exe, os.Args, os.Environ()); err != nil {
-						logger.Error("Failed to re-exec for restart: %v", err)
+					if err := reexec(); err != nil {
+						logger.Error("Failed to restart: %v", err)
 						os.Exit(1)
 					}
 				}

reexec_unix.go

@@ -0,0 +1,21 @@
+//go:build !windows
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+// reexec replaces the current process image with a fresh copy of itself,
+// preserving all arguments and environment variables. On success it never
+// returns (execve replaces the process in-place). On failure it returns an
+// error describing why the exec could not be performed.
+func reexec() error {
+	exe, err := os.Executable()
+	if err != nil {
+		return fmt.Errorf("failed to get executable path: %w", err)
+	}
+	return syscall.Exec(exe, os.Args, os.Environ())
+}

reexec_windows.go

@@ -0,0 +1,30 @@
+//go:build windows
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+)
+
+// reexec spawns a new copy of the current process with the same arguments and
+// environment, then exits the current process. On Windows, execve is not
+// available, so we start a child process and exit. On success it never returns
+// (os.Exit terminates the current process). On failure it returns an error.
+func reexec() error {
+	exe, err := os.Executable()
+	if err != nil {
+		return fmt.Errorf("failed to get executable path: %w", err)
+	}
+	cmd := exec.Command(exe, os.Args[1:]...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.Stdin = os.Stdin
+	cmd.Env = os.Environ()
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("failed to start new process: %w", err)
+	}
+	os.Exit(0)
+	return nil // unreachable
+}