~bigbes/shroud

ref: 3defea82da661a79fbae52bda7225127ce4b13f8 shroud/cmd/shroud/main.go -rw-r--r-- 29.9 KiB
3defea82 — Eugene Blikh feat(vless): add scan command for reality targets 2 months ago
                                                                                
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package main

import (
	"crypto/rand"
	"crypto/sha256"
	"crypto/tls"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"net/netip"
	"os"
	"os/signal"
	"path/filepath"
	"sync"
	"syscall"
	"time"

	"golang.getoutline.org/tunnel-server/ipinfo"
	"github.com/google/uuid"
	"github.com/lmittmann/tint"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/spf13/cobra"
	"golang.org/x/term"
	"gopkg.in/yaml.v3"

	"encoding/base64"

	"sourcecraft.dev/bigbes/shroud/internal/api"
	"sourcecraft.dev/bigbes/shroud/internal/awgserver"
	"sourcecraft.dev/bigbes/shroud/internal/config"
	"sourcecraft.dev/bigbes/shroud/internal/metrics"
	"sourcecraft.dev/bigbes/shroud/internal/mmdb"
	"sourcecraft.dev/bigbes/shroud/internal/reality"
	"sourcecraft.dev/bigbes/shroud/internal/ssserver"
	"sourcecraft.dev/bigbes/shroud/internal/store"
	"sourcecraft.dev/bigbes/shroud/internal/vless"
)

var version = "dev"

func main() {
	if err := newRootCmd().Execute(); err != nil {
		os.Exit(1)
	}
}

func newRootCmd() *cobra.Command {
	var (
		configFile string
		verbose    bool
	)

	root := &cobra.Command{
		Use:     "shroud",
		Short:   "Shadowsocks + AmneziaWG + VLESS VPN server",
		Version: version,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runServe(configFile, verbose)
		},
		SilenceUsage:  true,
		SilenceErrors: true,
	}

	pf := root.PersistentFlags()
	pf.StringVarP(&configFile, "config", "c", "config.yaml", "configuration file path")
	pf.BoolVarP(&verbose, "verbose", "v", false, "enable debug logging")

	root.AddCommand(
		newCompletionCmd(),
		newKeyCmd(&configFile),
		newServerCmd(&configFile),
		newVLESSCmd(&configFile),
	)

	return root
}

// --- completion ---

func newCompletionCmd() *cobra.Command {
	cmd := &cobra.Command{
		Use:   "completion [bash|zsh|fish|powershell]",
		Short: "Generate shell completion scripts",
		Long: `Generate shell completion scripts for shroud.

To load completions:

Bash:
  $ source <(shroud completion bash)
  # To install permanently:
  $ shroud completion bash > /etc/bash_completion.d/shroud

Zsh:
  $ source <(shroud completion zsh)
  # To install permanently:
  $ shroud completion zsh > "${fpath[1]}/_shroud"

Fish:
  $ shroud completion fish | source
  # To install permanently:
  $ shroud completion fish > ~/.config/fish/completions/shroud.fish

PowerShell:
  PS> shroud completion powershell | Out-String | Invoke-Expression
`,
		DisableFlagsInUseLine: true,
		ValidArgs:             []string{"bash", "zsh", "fish", "powershell"},
		Args:                  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			switch args[0] {
			case "bash":
				return cmd.Root().GenBashCompletion(os.Stdout)
			case "zsh":
				return cmd.Root().GenZshCompletion(os.Stdout)
			case "fish":
				return cmd.Root().GenFishCompletion(os.Stdout, true)
			case "powershell":
				return cmd.Root().GenPowerShellCompletionWithDesc(os.Stdout)
			default:
				return fmt.Errorf("unsupported shell: %s", args[0])
			}
		},
	}
	return cmd
}

// --- key commands ---

func newKeyCmd(configFile *string) *cobra.Command {
	cmd := &cobra.Command{
		Use:   "key",
		Short: "Manage access keys",
	}
	cmd.AddCommand(
		newKeyListCmd(configFile),
		newKeyAddCmd(configFile),
		newKeyRemoveCmd(configFile),
		newKeyRenameCmd(configFile),
	)
	return cmd
}

func newKeyListCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "list",
		Short: "List all access keys",
		Args:  cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			keys := st.ListKeys()
			if len(keys) == 0 {
				fmt.Println("No access keys configured.")
				return nil
			}
			for _, k := range keys {
				limit := "none"
				if k.DataLimit != nil {
					limit = fmt.Sprintf("%d bytes", k.DataLimit.Bytes)
				}
				awgInfo := ""
				if k.AWG != nil {
					awgInfo = fmt.Sprintf("  awg=%s", k.AWG.AllowedIP)
				}
				vlessInfo := ""
				if k.VLESS != nil {
					vlessInfo = fmt.Sprintf("  vless=%s", k.VLESS.UUID)
				}
				fmt.Printf("%-6s  %-20s  port=%-6d  cipher=%s  limit=%s%s%s\n",
					k.ID, k.Name, k.Port, k.Method, limit, awgInfo, vlessInfo)
			}
			return nil
		},
	}
}

func newKeyAddCmd(configFile *string) *cobra.Command {
	var (
		name   string
		port   int
		cipher string
	)
	cmd := &cobra.Command{
		Use:   "add",
		Short: "Add a new access key",
		Args:  cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			cfg, err := config.Load(*configFile)
			if err != nil {
				return fmt.Errorf("loading config: %w", err)
			}
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			srv := st.GetServer()

			password, err := store.GeneratePassword()
			if err != nil {
				return err
			}

			id := fmt.Sprintf("%d", srv.NextID)
			if err := st.UpdateServer(func(s *store.ServerState) {
				s.NextID++
			}); err != nil {
				return err
			}

			if cipher == "" {
				cipher = srv.DefaultCipher
			}
			if port == 0 {
				port = srv.PortForNewAccessKeys
			}

			ak := store.AccessKey{
				ID:       id,
				Name:     name,
				Password: password,
				Port:     port,
				Method:   cipher,
			}

			// Generate AWG credentials if AWG is enabled.
			if cfg.AmneziaWG.Enabled && cfg.AmneziaWG.Address != "" {
				privKey, err := awgserver.GeneratePrivateKey()
				if err != nil {
					return fmt.Errorf("generating AWG key: %w", err)
				}
				pubKey, err := awgserver.PublicKeyFromPrivate(privKey)
				if err != nil {
					return fmt.Errorf("deriving AWG public key: %w", err)
				}
				keys := st.ListKeys()
				used := make([]string, 0, len(keys))
				for _, k := range keys {
					if k.AWG != nil {
						used = append(used, k.AWG.AllowedIP)
					}
				}
				alloc, err := awgserver.NewIPAllocator(cfg.AmneziaWG.Address)
				if err != nil {
					return fmt.Errorf("creating IP allocator: %w", err)
				}
				ip, err := alloc.Allocate(used)
				if err != nil {
					return fmt.Errorf("allocating AWG IP: %w", err)
				}
				ak.AWG = &store.AWGKeyData{
					PrivateKey: privKey,
					PublicKey:  pubKey,
					AllowedIP:  ip,
				}
			}

			// Generate VLESS credentials if VLESS is enabled.
			if cfg.VLESS.Enabled {
				ak.VLESS = &store.VLESSKeyData{
					UUID: uuid.New().String(),
				}
			}

			if err := st.CreateKey(ak); err != nil {
				return err
			}
			fmt.Printf("Created key %s (port=%d, cipher=%s)\n", id, port, cipher)
			fmt.Printf("  ss://%s\n", password)
			if ak.AWG != nil {
				fmt.Printf("  awg: %s (pubkey=%s)\n", ak.AWG.AllowedIP, ak.AWG.PublicKey)
			}
			if ak.VLESS != nil {
				fmt.Printf("  vless: %s\n", ak.VLESS.UUID)
			}
			return nil
		},
	}
	cmd.Flags().StringVarP(&name, "name", "n", "", "key name")
	cmd.Flags().IntVarP(&port, "port", "p", 0, "port (default: server's default port)")
	cmd.Flags().StringVar(&cipher, "cipher", "", "cipher (default: server's default cipher)")
	return cmd
}

func newKeyRemoveCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "remove <id>",
		Short: "Remove an access key",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			if err := st.DeleteKey(args[0]); err != nil {
				return err
			}
			fmt.Printf("Removed key %s\n", args[0])
			return nil
		},
	}
}

func newKeyRenameCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "rename <id> <name>",
		Short: "Rename an access key",
		Args:  cobra.ExactArgs(2),
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			return st.UpdateKey(args[0], func(k *store.AccessKey) {
				k.Name = args[1]
			})
		},
	}
}

// --- server commands ---

func newServerCmd(configFile *string) *cobra.Command {
	cmd := &cobra.Command{
		Use:   "server",
		Short: "Server configuration commands",
	}
	cmd.AddCommand(
		newServerInfoCmd(configFile),
		newServerSetPortCmd(configFile),
		newServerSetHostnameCmd(configFile),
		newServerSetNameCmd(configFile),
	)
	return cmd
}

func newServerInfoCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "info",
		Short: "Show server configuration",
		Args:  cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			srv := st.GetServer()
			fmt.Printf("Server ID:        %s\n", srv.ID)
			fmt.Printf("Name:             %s\n", srv.Name)
			fmt.Printf("Hostname:         %s\n", srv.Hostname)
			fmt.Printf("Default Port:     %d\n", srv.PortForNewAccessKeys)
			fmt.Printf("Default Cipher:   %s\n", srv.DefaultCipher)
			fmt.Printf("Metrics Enabled:  %v\n", srv.MetricsEnabled)
			fmt.Printf("Access Keys:      %d\n", len(st.ListKeys()))
			if srv.AccessKeyDataLimit != nil {
				fmt.Printf("Data Limit:       %d bytes\n", srv.AccessKeyDataLimit.Bytes)
			}
			return nil
		},
	}
}

func newServerSetPortCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "set-port <port>",
		Short: "Set the default port for new access keys",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			var port int
			if _, err := fmt.Sscanf(args[0], "%d", &port); err != nil || port < 1 || port > 65535 {
				return fmt.Errorf("invalid port: %s", args[0])
			}
			if err := st.UpdateServer(func(s *store.ServerState) {
				s.PortForNewAccessKeys = port
			}); err != nil {
				return err
			}
			fmt.Printf("Default port set to %d\n", port)
			return nil
		},
	}
}

func newServerSetHostnameCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "set-hostname <hostname>",
		Short: "Set the hostname for access key URLs",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			if err := st.UpdateServer(func(s *store.ServerState) {
				s.Hostname = args[0]
			}); err != nil {
				return err
			}
			fmt.Printf("Hostname set to %s\n", args[0])
			return nil
		},
	}
}

func newServerSetNameCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "set-name <name>",
		Short: "Set the server display name",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			if err := st.UpdateServer(func(s *store.ServerState) {
				s.Name = args[0]
			}); err != nil {
				return err
			}
			fmt.Printf("Server name set to %s\n", args[0])
			return nil
		},
	}
}

// --- helpers ---

func openStore(configFile string) (*store.YAMLFileStore, error) {
	cfg, err := config.Load(configFile)
	if err != nil {
		return nil, fmt.Errorf("loading config: %w", err)
	}
	return store.NewYAMLFileStore(
		cfg.StateFile(),
		"", cfg.Server.Name, cfg.Server.Hostname,
		cfg.Shadowsocks.DefaultCipher, cfg.Shadowsocks.DefaultPort,
	)
}

// --- access info YAML ---

type accessInfo struct {
	APIURL     string `yaml:"api_url"`
	CertSHA256 string `yaml:"cert_sha256"`
}

func writeAccessInfo(apiAddr, secret, certFile, infoFile string) error {
	certSHA256 := ""
	if certFile != "" {
		cert, err := tls.LoadX509KeyPair(certFile, certFile)
		if err == nil && len(cert.Certificate) > 0 {
			hash := sha256.Sum256(cert.Certificate[0])
			certSHA256 = hex.EncodeToString(hash[:])
		}
	}

	info := accessInfo{
		APIURL:     fmt.Sprintf("https://%s/%s", apiAddr, secret),
		CertSHA256: certSHA256,
	}

	data, err := yaml.Marshal(info)
	if err != nil {
		return err
	}
	return os.WriteFile(infoFile, data, 0600)
}

// --- serve ---

func runServe(configFile string, verbose bool) error {
	logLevel := new(slog.LevelVar)
	logHandler := tint.NewHandler(
		os.Stderr,
		&tint.Options{NoColor: !term.IsTerminal(int(os.Stderr.Fd())), Level: logLevel},
	)
	logger := slog.New(logHandler)
	slog.SetDefault(logger)

	if verbose {
		logLevel.Set(slog.LevelDebug)
	}

	cfg, err := config.Load(configFile)
	if err != nil {
		return fmt.Errorf("loading config: %w", err)
	}

	// Generate server ID if not set.
	serverID := cfg.Server.ID
	if serverID == "" {
		serverID = uuid.New().String()
	}

	// Generate API secret if not set.
	apiSecret := cfg.API.Secret
	if apiSecret == "" {
		buf := make([]byte, 16)
		if _, err := rand.Read(buf); err != nil {
			return fmt.Errorf("generating API secret: %w", err)
		}
		apiSecret = hex.EncodeToString(buf)
		logger.Info("Generated API secret.", "secret", apiSecret)
	}

	// Set up MMDB files (download if needed, start auto-update).
	mmdbMgr, err := mmdb.NewManager(cfg.Shadowsocks.MMDBConfig(), logger)
	if err != nil {
		return fmt.Errorf("setting up MMDB manager: %w", err)
	}
	mmdbPaths, err := mmdbMgr.Resolve()
	if err != nil {
		return fmt.Errorf("resolving MMDB files: %w", err)
	}
	mmdbMgr.StartAutoUpdate()
	defer mmdbMgr.Stop()

	// Set up IP info for geo-metrics.
	var ip2info ipinfo.IPInfoMap
	if mmdbPaths.CountryPath != "" || mmdbPaths.ASNPath != "" {
		mmdbMap, err := ipinfo.NewMMDBIPInfoMap(mmdbPaths.CountryPath, mmdbPaths.ASNPath)
		if err != nil {
			return fmt.Errorf("loading IP info databases: %w", err)
		}
		defer mmdbMap.Close()
		ip2info = mmdbMap
	}

	// Set up metrics.
	serverMetrics := metrics.NewServerMetrics()
	registry, transferTracker, _, err := metrics.SetupRegistry(
		ip2info,
		serverMetrics,
		version,
		cfg.Metrics.NodeExporterCollectors,
		logger,
	)
	if err != nil {
		return fmt.Errorf("setting up metrics: %w", err)
	}

	// Set up persistent store.
	st, err := store.NewYAMLFileStore(
		cfg.StateFile(),
		serverID,
		cfg.Server.Name,
		cfg.Server.Hostname,
		cfg.Shadowsocks.DefaultCipher,
		cfg.Shadowsocks.DefaultPort,
	)
	if err != nil {
		return fmt.Errorf("initializing store: %w", err)
	}

	// Set up Shadowsocks server (optional).
	var ss *ssserver.Server
	if *cfg.Shadowsocks.Enabled {
		natTimeout, err := time.ParseDuration(cfg.Shadowsocks.NATTimeout)
		if err != nil {
			return fmt.Errorf("invalid NAT timeout: %w", err)
		}

		// Pick a random unused port for Shadowsocks if not configured.
		ssDefaultPort := cfg.Shadowsocks.DefaultPort
		if ssDefaultPort == 0 {
			p, err := pickRandomPort()
			if err != nil {
				return fmt.Errorf("picking random port for shadowsocks: %w", err)
			}
			ssDefaultPort = p
			logger.Info("Selected random port for new access keys.", "port", ssDefaultPort)
		}

		ss = ssserver.New(
			natTimeout,
			cfg.Shadowsocks.ReplayHistory,
			serverMetrics,
			transferTracker,
			logger,
		)

		// Start with existing keys.
		if keys := st.ListKeys(); len(keys) > 0 {
			if err := ss.SyncKeys(keys); err != nil {
				return fmt.Errorf("starting Shadowsocks with existing keys: %w", err)
			}
			logger.Info("Loaded existing access keys.", "count", len(keys))
		}
		logger.Info("Shadowsocks server enabled.")
	}

	// Set up AmneziaWG server (optional).
	var awg *awgserver.Server
	if cfg.AmneziaWG.Enabled {
		// Ensure server has AWG keypair.
		srv := st.GetServer()
		if srv.AWGPrivateKey == "" {
			privKey, err := awgserver.GeneratePrivateKey()
			if err != nil {
				return fmt.Errorf("generating AWG server key: %w", err)
			}
			pubKey, err := awgserver.PublicKeyFromPrivate(privKey)
			if err != nil {
				return fmt.Errorf("deriving AWG server public key: %w", err)
			}
			if err := st.UpdateServer(func(s *store.ServerState) {
				s.AWGPrivateKey = privKey
				s.AWGPublicKey = pubKey
			}); err != nil {
				return fmt.Errorf("persisting AWG server key: %w", err)
			}
			logger.Info("Generated AWG server keypair.")
			srv = st.GetServer()
		}

		// Parse H1-H4 ranges.
		h1, err := awgserver.ParseHeaderRange(cfg.AmneziaWG.H1)
		if err != nil {
			return fmt.Errorf("parsing AWG H1: %w", err)
		}
		h2, err := awgserver.ParseHeaderRange(cfg.AmneziaWG.H2)
		if err != nil {
			return fmt.Errorf("parsing AWG H2: %w", err)
		}
		h3, err := awgserver.ParseHeaderRange(cfg.AmneziaWG.H3)
		if err != nil {
			return fmt.Errorf("parsing AWG H3: %w", err)
		}
		h4, err := awgserver.ParseHeaderRange(cfg.AmneziaWG.H4)
		if err != nil {
			return fmt.Errorf("parsing AWG H4: %w", err)
		}

		// Build server address from subnet (take .1).
		alloc, err := awgserver.NewIPAllocator(cfg.AmneziaWG.Address)
		if err != nil {
			return fmt.Errorf("parsing AWG address: %w", err)
		}
		serverAddr := fmt.Sprintf("%s/%d", alloc.ServerIP().String(), netip.MustParsePrefix(cfg.AmneziaWG.Address).Bits())

		awgCfg := awgserver.Config{
			ListenPort:   cfg.AmneziaWG.ListenPort,
			TUNName:      cfg.AmneziaWG.TUNName,
			Address:      serverAddr,
			MTU:          cfg.AmneziaWG.MTU,
			PrivateKey:   srv.AWGPrivateKey,
			MuxEnabled:   cfg.AmneziaWG.AWGMuxEnabled(),
			Domain:       cfg.AmneziaWG.Domain,
			CertCache:    cfg.ACME.CertCache,
			ACMEHTTPPort: cfg.ACME.HTTPPort,
			Jc:           cfg.AmneziaWG.Jc,
			Jmin:         cfg.AmneziaWG.Jmin,
			Jmax:         cfg.AmneziaWG.Jmax,
			S1:           cfg.AmneziaWG.S1,
			S2:           cfg.AmneziaWG.S2,
			S3:           cfg.AmneziaWG.S3,
			S4:           cfg.AmneziaWG.S4,
			H1:           h1,
			H2:           h2,
			H3:           h3,
			H4:           h4,
		}

		awg = awgserver.New(awgCfg, logger)
		if err := awg.Start(); err != nil {
			return fmt.Errorf("starting AWG server: %w", err)
		}

		if keys := st.ListKeys(); len(keys) > 0 {
			if err := awg.SyncKeys(keys); err != nil {
				return fmt.Errorf("syncing AWG peers: %w", err)
			}
		}
		logger.Info("AmneziaWG server started.", "port", cfg.AmneziaWG.ListenPort)
	}

	// Set up VLESS+REALITY server (optional).
	var vlessServer *vless.Server
	if cfg.VLESS.Enabled {
		srv := st.GetServer()
		if srv.VLESSPrivateKey == "" {
			priv, pub, err := vless.GenerateX25519Keypair()
			if err != nil {
				return fmt.Errorf("generating REALITY keypair: %w", err)
			}
			shortID, err := vless.GenerateShortID()
			if err != nil {
				return fmt.Errorf("generating REALITY short ID: %w", err)
			}
			if err := st.UpdateServer(func(s *store.ServerState) {
				s.VLESSPrivateKey = priv
				s.VLESSPublicKey = pub
				s.VLESSShortID = shortID
			}); err != nil {
				return fmt.Errorf("persisting REALITY keys: %w", err)
			}
			logger.Info("Generated REALITY keypair.")
			srv = st.GetServer()
		}

		privKey, err := base64.StdEncoding.DecodeString(srv.VLESSPrivateKey)
		if err != nil {
			return fmt.Errorf("decoding REALITY private key: %w", err)
		}
		var shortID [8]byte
		shortIDBytes, err := hex.DecodeString(srv.VLESSShortID)
		if err != nil {
			return fmt.Errorf("decoding REALITY short ID: %w", err)
		}
		copy(shortID[:], shortIDBytes)

		pubKey, err := base64.StdEncoding.DecodeString(srv.VLESSPublicKey)
		if err != nil {
			return fmt.Errorf("decoding REALITY public key: %w", err)
		}

		vlessCfg := vless.Config{
			ListenAddr:  cfg.VLESS.ListenAddr,
			PrivateKey:  privKey,
			PublicKey:   pubKey,
			ShortID:     shortID,
			ServerNames: cfg.VLESS.ServerNames,
			Dest:        cfg.VLESS.Dest,
			Show:        cfg.VLESS.Show,
		}

		vlessServer = vless.New(vlessCfg, logger)
		if err := vlessServer.Start(); err != nil {
			return fmt.Errorf("starting VLESS server: %w", err)
		}

		if keys := st.ListKeys(); len(keys) > 0 {
			if err := vlessServer.SyncKeys(keys); err != nil {
				return fmt.Errorf("syncing VLESS keys: %w", err)
			}
		}
		logger.Info("VLESS+REALITY server started.", "addr", cfg.VLESS.ListenAddr)
	}

	// Start Prometheus metrics + /healthz endpoint.
	metricsHandler := promhttp.HandlerFor(registry, promhttp.HandlerOpts{})
	metricsMux := http.NewServeMux()
	metricsMux.Handle("/metrics", metricsHandler)
	metricsMux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		json.NewEncoder(w).Encode(map[string]any{
			"healthy":    true,
			"version":    version,
			"accessKeys": len(st.ListKeys()),
		})
	})
	metricsServer := &http.Server{Addr: cfg.Metrics.ListenAddr, Handler: metricsMux}
	go func() {
		logger.Info("Prometheus metrics server started.", "address", cfg.Metrics.ListenAddr)
		if err := metricsServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			logger.Error("Metrics server failed.", "err", err)
		}
	}()

	// Start REST API.
	var awgCfgPtr *config.AmneziaWGConfig
	if cfg.AmneziaWG.Enabled {
		awgCfgPtr = &cfg.AmneziaWG
	}
	handler := api.NewHandler(st, ss, awg, awgCfgPtr, vlessServer, transferTracker, version, logger)
	router := api.NewRouter(apiSecret, handler)
	apiServer := &http.Server{Addr: cfg.API.ListenAddr, Handler: router}
	go func() {
		logger.Info("Management API started.", "address", cfg.API.ListenAddr, "prefix", "/"+apiSecret)
		if err := apiServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			logger.Error("API server failed.", "err", err)
		}
	}()

	// Write access info.
	infoFile := filepath.Join(filepath.Dir(cfg.StateFile()), "access.yaml")
	if err := writeAccessInfo(cfg.API.ListenAddr, apiSecret, cfg.API.CertFile, infoFile); err != nil {
		logger.Warn("Failed to write access info.", "err", err)
	} else {
		logger.Info("Access info written.", "file", infoFile)
	}

	logger.Info("shroud started.",
		"version", version,
		"api", cfg.API.ListenAddr,
		"metrics", cfg.Metrics.ListenAddr,
	)

	// Wait for shutdown signal.
	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
	<-sigCh

	logger.Info("Shutting down...")
	if vlessServer != nil {
		vlessServer.Stop()
	}
	if awg != nil {
		awg.Stop()
	}
	if ss != nil {
		ss.Stop()
	}
	apiServer.Close()
	metricsServer.Close()

	return nil
}

// --- vless commands ---

func newVLESSCmd(configFile *string) *cobra.Command {
	cmd := &cobra.Command{
		Use:   "vless",
		Short: "VLESS+REALITY management commands",
	}
	cmd.AddCommand(
		newVLESSKeygenCmd(),
		newVLESSInfoCmd(configFile),
		newVLESSShareCmd(configFile),
		newVLESSScanCmd(),
	)
	return cmd
}

func newVLESSKeygenCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "keygen",
		Short: "Generate a new REALITY x25519 keypair and short ID",
		Args:  cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			priv, pub, err := vless.GenerateX25519Keypair()
			if err != nil {
				return err
			}
			shortID, err := vless.GenerateShortID()
			if err != nil {
				return err
			}
			fmt.Printf("Private Key: %s\n", priv)
			fmt.Printf("Public Key:  %s\n", pub)
			fmt.Printf("Short ID:    %s\n", shortID)
			return nil
		},
	}
}

func newVLESSInfoCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "info",
		Short: "Show VLESS+REALITY server info",
		Args:  cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) error {
			cfg, err := config.Load(*configFile)
			if err != nil {
				return fmt.Errorf("loading config: %w", err)
			}
			if !cfg.VLESS.Enabled {
				fmt.Println("VLESS is not enabled.")
				return nil
			}
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			srv := st.GetServer()
			fmt.Printf("Listen Addr:  %s\n", cfg.VLESS.ListenAddr)
			fmt.Printf("Server Names: %v\n", cfg.VLESS.ServerNames)
			fmt.Printf("Dest:         %s\n", cfg.VLESS.Dest)
			if srv.VLESSPublicKey != "" {
				fmt.Printf("Public Key:   %s\n", srv.VLESSPublicKey)
				fmt.Printf("Short ID:     %s\n", srv.VLESSShortID)
			} else {
				fmt.Println("REALITY keypair not yet generated (start the server first).")
			}
			return nil
		},
	}
}

func newVLESSShareCmd(configFile *string) *cobra.Command {
	return &cobra.Command{
		Use:   "share <key-id>",
		Short: "Generate a VLESS share link for a key",
		Args:  cobra.ExactArgs(1),
		RunE: func(cmd *cobra.Command, args []string) error {
			cfg, err := config.Load(*configFile)
			if err != nil {
				return fmt.Errorf("loading config: %w", err)
			}
			if !cfg.VLESS.Enabled {
				return fmt.Errorf("VLESS is not enabled")
			}
			st, err := openStore(*configFile)
			if err != nil {
				return err
			}
			srv := st.GetServer()
			if srv.VLESSPublicKey == "" {
				return fmt.Errorf("REALITY keypair not yet generated (start the server first)")
			}

			key, ok := st.GetKey(args[0])
			if !ok {
				return fmt.Errorf("key %q not found", args[0])
			}
			if key.VLESS == nil {
				return fmt.Errorf("key %q has no VLESS credentials", args[0])
			}

			hostname := srv.Hostname
			if hostname == "" {
				hostname = "localhost"
			}

			// Extract port from listen address.
			_, portStr, err := net.SplitHostPort(cfg.VLESS.ListenAddr)
			if err != nil {
				portStr = "443"
			}

			sni := ""
			if len(cfg.VLESS.ServerNames) > 0 {
				sni = cfg.VLESS.ServerNames[0]
			}

			// Base64url encode the public key (no padding).
			pubKeyB64URL := base64.RawURLEncoding.EncodeToString([]byte(srv.VLESSPublicKey))

			name := key.Name
			if name == "" {
				name = key.ID
			}

			fmt.Printf("vless://%s@%s:%s?encryption=none&security=reality&sni=%s&fp=chrome&pbk=%s&sid=%s&type=tcp#%s\n",
				key.VLESS.UUID, hostname, portStr, sni, pubKeyB64URL, srv.VLESSShortID, name)
			return nil
		},
	}
}

func newVLESSScanCmd() *cobra.Command {
	var (
		addr    string
		inFile  string
		urlFlag string
		port    int
		threads int
		timeout int
		outFile string
		ipv6    bool
	)

	cmd := &cobra.Command{
		Use:   "scan",
		Short: "Scan TLS servers to find REALITY-suitable decoy targets",
		Long: `Scan TLS servers and identify those suitable for use as REALITY decoy targets.
A server is feasible if it negotiates TLS 1.3 with HTTP/2 ALPN and presents
a certificate with a valid Common Name and Issuer.

Exactly one of --addr, --in, or --url must be specified.`,
		RunE: func(cmd *cobra.Command, args []string) error {
			return runVLESSScan(cmd, addr, inFile, urlFlag, port, threads, timeout, outFile, ipv6)
		},
	}

	f := cmd.Flags()
	f.StringVar(&addr, "addr", "", "single target: IP, CIDR, or domain")
	f.StringVar(&inFile, "in", "", "file with line-separated targets")
	f.StringVar(&urlFlag, "url", "", "HTTP URL to crawl for domains")
	f.IntVar(&port, "port", 443, "target TLS port")
	f.IntVar(&threads, "threads", 2, "number of concurrent scan workers")
	f.IntVar(&timeout, "timeout", 10, "per-scan timeout in seconds")
	f.StringVar(&outFile, "out", "out.csv", "output CSV file path")
	f.BoolVar(&ipv6, "ipv6", false, "include IPv6 addresses")

	return cmd
}

func runVLESSScan(cmd *cobra.Command, addr, inFile, urlFlag string, port, threads, timeout int, outFile string, ipv6 bool) error {
	// Validate: exactly one input source.
	sources := 0
	if addr != "" {
		sources++
	}
	if inFile != "" {
		sources++
	}
	if urlFlag != "" {
		sources++
	}
	if sources != 1 {
		return fmt.Errorf("exactly one of --addr, --in, or --url must be specified")
	}

	logger := slog.Default()

	scanCfg := reality.ScanConfig{
		Port:    port,
		Timeout: time.Duration(timeout) * time.Second,
	}

	// Set up GeoIP resolver (best-effort).
	var geo *reality.GeoResolver
	cfg, cfgErr := config.Load(cmd.Root().Flag("config").Value.String())
	if cfgErr == nil {
		mmdbCfg := mmdb.Config{
			CountryURL: cfg.Shadowsocks.IPCountryDB,
			CacheDir:   cfg.Shadowsocks.IPDBCacheDir,
		}
		mgr, err := mmdb.NewManager(mmdbCfg, logger)
		if err == nil {
			result, err := mgr.Resolve()
			if err == nil {
				geo, _ = reality.NewGeoResolver(result.CountryPath)
			}
		}
	}
	if geo == nil {
		// Try with defaults if config loading failed.
		mgr, err := mmdb.NewManager(mmdb.Config{}, logger)
		if err == nil {
			result, err := mgr.Resolve()
			if err == nil {
				geo, _ = reality.NewGeoResolver(result.CountryPath)
			}
		}
	}
	defer geo.Close()

	// Open CSV output file.
	csvFile, err := os.Create(outFile)
	if err != nil {
		return fmt.Errorf("creating output file: %w", err)
	}
	defer csvFile.Close()
	fmt.Fprintln(csvFile, "IP,ORIGIN,CERT_DOMAIN,CERT_ISSUER,GEO_CODE")

	// Set up context with SIGINT cancellation.
	ctx, cancel := signal.NotifyContext(cmd.Context(), os.Interrupt, syscall.SIGTERM)
	defer cancel()

	// Build host channel from input source.
	hostCh := make(chan reality.Host, threads*4)
	go func() {
		defer close(hostCh)
		switch {
		case addr != "":
			hosts, err := reality.ParseTarget(addr, ipv6)
			if err != nil {
				logger.Error("Failed to parse target.", "addr", addr, "err", err)
				return
			}
			for _, h := range hosts {
				select {
				case hostCh <- h:
				case <-ctx.Done():
					return
				}
			}
		case inFile != "":
			f, err := os.Open(inFile)
			if err != nil {
				logger.Error("Failed to open input file.", "path", inFile, "err", err)
				return
			}
			defer f.Close()
			for h := range reality.ParseTargetsFromReader(f, ipv6) {
				select {
				case hostCh <- h:
				case <-ctx.Done():
					return
				}
			}
		case urlFlag != "":
			hosts, err := reality.ParseTargetsFromURL(urlFlag, ipv6)
			if err != nil {
				logger.Error("Failed to fetch URL targets.", "url", urlFlag, "err", err)
				return
			}
			for _, h := range hosts {
				select {
				case hostCh <- h:
				case <-ctx.Done():
					return
				}
			}
		}
	}()

	// Worker pool.
	var (
		wg       sync.WaitGroup
		mu       sync.Mutex
		total    int
		feasible int
	)
	for i := 0; i < threads; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for host := range hostCh {
				result := reality.ScanHost(ctx, host, scanCfg)
				result.GeoCode = geo.Lookup(host.IP)

				mu.Lock()
				total++
				if result.Error != nil {
					logger.Debug("Scan failed.",
						"ip", result.IP, "origin", result.Origin, "err", result.Error)
				} else if result.Feasible {
					feasible++
					fmt.Fprintf(csvFile, "%s,%s,%s,%q,%s\n",
						result.IP, result.Origin, result.CertDomain, result.CertIssuer, result.GeoCode)
					logger.Info("FEASIBLE",
						"ip", result.IP, "origin", result.Origin,
						"tls", reality.TLSVersionName(result.TLSVersion),
						"alpn", result.ALPN,
						"cn", result.CertDomain, "issuer", result.CertIssuer,
						"geo", result.GeoCode)
				} else {
					logger.Debug("Not feasible.",
						"ip", result.IP, "origin", result.Origin,
						"tls", reality.TLSVersionName(result.TLSVersion),
						"alpn", result.ALPN,
						"cn", result.CertDomain, "issuer", result.CertIssuer)
				}
				mu.Unlock()
			}
		}()
	}

	wg.Wait()
	fmt.Printf("\nScan complete: %d scanned, %d feasible. Results written to %s\n", total, feasible, outFile)
	return nil
}

func pickRandomPort() (int, error) {
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		return 0, err
	}
	port := ln.Addr().(*net.TCPAddr).Port
	ln.Close()
	return port, nil
}