Add daemon into newt

authdaemon.go

@@ -0,0 +1,151 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"runtime"
+
+	"github.com/fosrl/newt/authdaemon"
+	"github.com/fosrl/newt/logger"
+)
+
+const (
+	defaultPrincipalsPath = "/var/run/auth-daemon/principals"
+	defaultCACertPath     = "/etc/ssh/ca.pem"
+)
+
+var (
+	errPresharedKeyRequired = errors.New("auth-daemon-key is required when --auth-daemon is enabled")
+	errRootRequired         = errors.New("auth-daemon must be run as root (use sudo)")
+	authDaemonServer        *authdaemon.Server // Global auth daemon server instance
+)
+
+// startAuthDaemon initializes and starts the auth daemon in the background.
+// It validates requirements (Linux, root, preshared key) and starts the server
+// in a goroutine so it runs alongside normal newt operation.
+func startAuthDaemon(ctx context.Context) error {
+	// Validation
+	if runtime.GOOS != "linux" {
+		return fmt.Errorf("auth-daemon is only supported on Linux, not %s", runtime.GOOS)
+	}
+	if os.Geteuid() != 0 {
+		return errRootRequired
+	}
+
+	// Use defaults if not set
+	principalsFile := authDaemonPrincipalsFile
+	if principalsFile == "" {
+		principalsFile = defaultPrincipalsPath
+	}
+	caCertPath := authDaemonCACertPath
+	if caCertPath == "" {
+		caCertPath = defaultCACertPath
+	}
+
+	// Create auth daemon server
+	cfg := authdaemon.Config{
+		DisableHTTPS:       true, // We run without HTTP server in newt
+		PresharedKey:       "this-key-is-not-used",   // Not used in embedded mode, but set to non-empty to satisfy validation
+		PrincipalsFilePath: principalsFile,
+		CACertPath:         caCertPath,
+		Force:              true,
+	}
+
+	srv, err := authdaemon.NewServer(cfg)
+	if err != nil {
+		return fmt.Errorf("create auth daemon server: %w", err)
+	}
+
+	authDaemonServer = srv
+
+	// Start the auth daemon in a goroutine so it runs alongside newt
+	go func() {
+		logger.Info("Auth daemon starting (native mode, no HTTP server)")
+		if err := srv.Run(ctx); err != nil {
+			logger.Error("Auth daemon error: %v", err)
+		}
+		logger.Info("Auth daemon stopped")
+	}()
+
+	return nil
+}
+
+
+
+// runPrincipalsCmd executes the principals subcommand logic
+func runPrincipalsCmd(args []string) {
+	opts := struct {
+		PrincipalsFile string
+		Username       string
+	}{
+		PrincipalsFile: defaultPrincipalsPath,
+	}
+
+	// Parse flags manually
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--principals-file":
+			if i+1 >= len(args) {
+				fmt.Fprintf(os.Stderr, "Error: --principals-file requires a value\n")
+				os.Exit(1)
+			}
+			opts.PrincipalsFile = args[i+1]
+			i++
+		case "--username":
+			if i+1 >= len(args) {
+				fmt.Fprintf(os.Stderr, "Error: --username requires a value\n")
+				os.Exit(1)
+			}
+			opts.Username = args[i+1]
+			i++
+		case "--help", "-h":
+			printPrincipalsHelp()
+			os.Exit(0)
+		default:
+			fmt.Fprintf(os.Stderr, "Error: unknown flag: %s\n", args[i])
+			printPrincipalsHelp()
+			os.Exit(1)
+		}
+	}
+
+	// Validation
+	if opts.Username == "" {
+		fmt.Fprintf(os.Stderr, "Error: username is required\n")
+		printPrincipalsHelp()
+		os.Exit(1)
+	}
+
+	// Get principals
+	list, err := authdaemon.GetPrincipals(opts.PrincipalsFile, opts.Username)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+	if len(list) == 0 {
+		fmt.Println("")
+		return
+	}
+	for _, principal := range list {
+		fmt.Println(principal)
+	}
+}
+
+func printPrincipalsHelp() {
+	fmt.Fprintf(os.Stderr, `Usage: newt principals [flags]
+
+Output principals for a username (for AuthorizedPrincipalsCommand in sshd_config).
+Read the principals file and print principals that match the given username, one per line.
+Configure in sshd_config with AuthorizedPrincipalsCommand and %%u for the username.
+
+Flags:
+  --principals-file string   Path to the principals file (default "%s")
+  --username string          Username to look up (required)
+  --help, -h                 Show this help message
+
+Example:
+  newt principals --username alice
+
+`, defaultPrincipalsPath)
+}