rmm2/agent-linux/ws/handler.go

package ws

import (
	"context"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"log"
	"os"
	"os/exec"
	"strconv"
	"time"
)

type Handler struct {
	client *Client
}

func NewHandler(client *Client) *Handler {
	return &Handler{client: client}
}

func (h *Handler) HandleCommand(msg Message) {
	log.Printf("Command erhalten: %s (ID: %s)", msg.Command, msg.ID)

	var response Message
	response.Type = "response"
	response.ID = msg.ID

	switch msg.Command {
	case "exec":
		response = h.handleExec(msg)
	case "reboot":
		response = h.handleReboot(msg)
	case "tunnel_connect":
		response = h.handleTunnelConnect(msg)
	case "tunnel_disconnect":
		h.handleTunnelDisconnect(msg)
		return
	case "agent_update":
		response = h.handleAgentUpdate(msg)
	default:
		response.Status = "error"
		response.Error = fmt.Sprintf("Unbekanntes Command: %s", msg.Command)
	}

	if err := h.client.SendMessage(response); err != nil {
		log.Printf("Response senden fehlgeschlagen: %v", err)
	}
}

// handleExec fuehrt einen beliebigen Befehl aus
func (h *Handler) handleExec(msg Message) Message {
	response := Message{Type: "response", ID: msg.ID}

	command, ok := msg.Params["command"].(string)
	if !ok || command == "" {
		response.Status = "error"
		response.Error = "Parameter 'command' erforderlich"
		return response
	}

	timeoutSec := 30
	if t, ok := msg.Params["timeout"]; ok {
		if ts, ok := t.(float64); ok {
			timeoutSec = int(ts)
		} else if ts, ok := t.(string); ok {
			if parsed, err := strconv.Atoi(ts); err == nil {
				timeoutSec = parsed
			}
		}
	}

	output, err := h.runCommand(command, timeoutSec)

	if err != nil {
		response.Status = "error"
		response.Error = err.Error()
		response.Data = map[string]interface{}{"output": output}
	} else {
		response.Status = "ok"
		response.Data = map[string]interface{}{"output": output}
	}

	return response
}

// handleReboot fuehrt einen Reboot durch
func (h *Handler) handleReboot(msg Message) Message {
	response := Message{Type: "response", ID: msg.ID}

	delaySec := 5
	if d, ok := msg.Params["delay"].(float64); ok && d > 0 {
		delaySec = int(d)
	}

	log.Printf("Reboot angefordert (Verzoegerung: %ds)", delaySec)

	response.Status = "ok"
	response.Data = map[string]interface{}{
		"message": fmt.Sprintf("Reboot in %d Sekunden", delaySec),
	}

	go func() {
		time.Sleep(time.Duration(delaySec) * time.Second)
		log.Println("Reboot wird ausgefuehrt...")
		exec.Command("/sbin/shutdown", "-r", "now").Run()
	}()

	return response
}

// handleAgentUpdate aktualisiert den Agent
func (h *Handler) handleAgentUpdate(msg Message) Message {
	response := Message{Type: "response", ID: msg.ID}

	// Binary kommt als Base64 im Data-Feld
	data, ok := msg.Data.(map[string]interface{})
	if !ok {
		response.Status = "error"
		response.Error = "Ungueltige Daten"
		return response
	}

	binaryB64, _ := data["binary"].(string)
	expectedHash, _ := data["hash"].(string)
	newVersion, _ := data["version"].(string)

	if binaryB64 == "" || expectedHash == "" {
		response.Status = "error"
		response.Error = "Binary oder Hash fehlt"
		return response
	}

	log.Printf("Agent-Update empfangen: Version %s, Hash %s", newVersion, expectedHash[:16])

	// Base64 dekodieren
	binary, err := base64.StdEncoding.DecodeString(binaryB64)
	if err != nil {
		response.Status = "error"
		response.Error = fmt.Sprintf("Base64-Dekodierung fehlgeschlagen: %v", err)
		return response
	}

	// Hash pruefen
	hash := sha256.Sum256(binary)
	actualHash := hex.EncodeToString(hash[:])
	if actualHash != expectedHash {
		response.Status = "error"
		response.Error = fmt.Sprintf("Hash-Mismatch: erwartet %s, bekommen %s", expectedHash[:16], actualHash[:16])
		return response
	}

	// Aktuelles Binary finden
	binaryPath := "/usr/local/bin/rmm-agent-linux"
	if _, err := os.Stat(binaryPath); os.IsNotExist(err) {
		// Fallback: eigener Pfad
		binaryPath, _ = os.Executable()
	}

	// Backup vom alten Binary
	backupPath := binaryPath + ".old"
	if err := os.Rename(binaryPath, backupPath); err != nil {
		response.Status = "error"
		response.Error = fmt.Sprintf("Backup fehlgeschlagen: %v", err)
		return response
	}

	// Neues Binary schreiben
	if err := os.WriteFile(binaryPath, binary, 0755); err != nil {
		// Rollback
		os.Rename(backupPath, binaryPath)
		response.Status = "error"
		response.Error = fmt.Sprintf("Binary schreiben fehlgeschlagen: %v", err)
		return response
	}

	log.Printf("Neues Binary geschrieben: %s (%d bytes)", binaryPath, len(binary))

	response.Status = "ok"
	response.Data = map[string]interface{}{
		"message":     fmt.Sprintf("Update auf %s erfolgreich, Neustart...", newVersion),
		"old_version": data["old_version"],
		"new_version": newVersion,
	}

	// Response senden, dann Neustart
	go func() {
		time.Sleep(2 * time.Second)
		log.Printf("Agent-Neustart nach Update auf %s", newVersion)
		// Versuche systemd service restart, fallback zu kill + restart
		if err := exec.Command("systemctl", "restart", "rmm-agent-linux").Run(); err != nil {
			log.Printf("systemctl restart fehlgeschlagen, versuche manuelle Wiederbelebung: %v", err)
			// Als letzter Ausweg: sich selbst ersetzen
			os.Exit(0)
		}
	}()

	return response
}

// --- Tunnel Handlers ---

func (h *Handler) handleTunnelConnect(msg Message) Message {
	response := Message{Type: "response", ID: msg.ID}

	sessionID, _ := msg.Params["session_id"].(string)
	tunnelID, _ := msg.Params["tunnel_id"].(string)
	targetHost, _ := msg.Params["target_host"].(string)
	targetPortFloat, _ := msg.Params["target_port"].(float64)
	targetPort := int(targetPortFloat)

	if sessionID == "" || targetHost == "" || targetPort <= 0 {
		response.Status = "error"
		response.Error = "session_id, target_host und target_port erforderlich"
		return response
	}

	if err := h.client.tunnelManager.ConnectSession(sessionID, tunnelID, targetHost, targetPort); err != nil {
		response.Status = "error"
		response.Error = fmt.Sprintf("Session-Connect fehlgeschlagen: %v", err)
		return response
	}

	response.Status = "ok"
	response.Data = map[string]interface{}{"session_id": sessionID}
	return response
}

func (h *Handler) handleTunnelDisconnect(msg Message) {
	sessionID, _ := msg.Params["session_id"].(string)
	if sessionID != "" {
		h.client.tunnelManager.DisconnectSession(sessionID)
	}
}

// SendSessionData schickt Tunnel-Daten als Binary-Message zurueck zum Backend
func (h *Handler) SendSessionData(sessionID string, data []byte) error {
	idBytes := []byte(sessionID)
	if len(idBytes) > 255 {
		return fmt.Errorf("session_id zu lang")
	}

	message := make([]byte, 1+len(idBytes)+len(data))
	message[0] = byte(len(idBytes))
	copy(message[1:], idBytes)
	copy(message[1+len(idBytes):], data)

	return h.client.SendBinaryData(message)
}

// runCommand fuehrt einen Shell-Befehl mit Timeout aus
func (h *Handler) runCommand(command string, timeoutSec int) (string, error) {
	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeoutSec)*time.Second)
	defer cancel()

	cmd := exec.CommandContext(ctx, "/bin/sh", "-c", command)
	output, err := cmd.CombinedOutput()
	return string(output), err
}