# # Copyright (C) 2026 GNS3 Technologies Inc. # Author: Yue Guobin # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . """ MCP (Model Context Protocol) service for GNS3 server. Implements the standard MCP protocol over SSE transport using FastMCP: /v3/mcp/sse — SSE stream /v3/mcp/messages/ — JSON-RPC messages Tools are registered via @mcp.tool() decorators. """ import contextvars import json import asyncio import logging import socket from typing import Any, Annotated from urllib.parse import parse_qs from fastapi import APIRouter from fastapi.responses import Response from pydantic import Field from mcp.server.fastmcp import FastMCP from mcp.server.transport_security import TransportSecuritySettings from gns3server.config import Config from gns3server.services import auth_service from gns3server.utils.request_utils import extract_client_info from .projects import ( list_projects_handler, get_project_handler, create_project_handler, delete_project_handler, open_project_handler, close_project_handler, get_project_stats_handler, update_project_handler, duplicate_project_handler, get_project_readme_handler, update_project_readme_handler, ) from .nodes import ( get_nodes_handler, get_node_handler, start_node_handler, stop_node_handler, reload_node_handler, suspend_node_handler, create_node_handler, delete_node_handler, update_node_handler, get_node_console_info_handler, ) from .links import ( get_links_handler, get_link_handler, create_link_handler, delete_link_handler, update_link_handler, ) from .templates import ( list_templates_handler, get_template_handler, create_template_handler, update_template_handler, delete_template_handler, ) from .computes import ( list_computes_handler, get_compute_handler, get_compute_images_handler, ) log = logging.getLogger(__name__) # ── Server ready state ──────────────────────────────────────────────── # Tracks whether GNS3 server has completed initialization. # MCP connections wait up to 5 seconds for startup to complete, then return # 503 Service Unavailable if initialization is not complete to prevent # "Received request before initialization was complete" errors. _mcp_ready_event = asyncio.Event() def set_mcp_server_ready(ready: bool = True) -> None: """ Set MCP server ready state. Should be called after GNS3 startup completes (database, controller, etc.) to allow MCP connections to proceed. Args: ready: True to mark server as ready, False to mark as not ready """ if ready: _mcp_ready_event.set() log.info("MCP server is now ready to accept connections") else: _mcp_ready_event.clear() async def wait_for_mcp_ready() -> bool: """ Wait until MCP server is ready before accepting connections. Returns: True if server is ready, False if timeout reached Returns immediately if already ready. Otherwise waits with a timeout and returns False if server does not become ready in time. """ if _mcp_ready_event.is_set(): return True log.debug("MCP server not ready yet, waiting for initialization to complete...") try: await asyncio.wait_for(_mcp_ready_event.wait(), timeout=5.0) log.debug("MCP server is now ready, proceeding with connection") return True except asyncio.TimeoutError: log.warning( "MCP server ready check timed out after 5 seconds - " "GNS3 server initialization may have issues" ) return False # ── Per‑connection JWT token ───────────────────────────────────────── # Set during SSE authentication, read by tool handlers running in the # same asyncio task (contextvars propagate through asyncio.to_thread). _jwt_token_var: contextvars.ContextVar[str | None] = contextvars.ContextVar( "mcp_jwt_token", default=None ) # ── Token validation ────────────────────────────────────────────────── async def _validate_token(token: str) -> bool: """Return True if token is a valid GNS3 JWT.""" try: auth_service.get_username_from_token(token) return True except Exception: return False # ── Server URL helper ───────────────────────────────────────────────── def _server_url() -> str: cfg = Config.instance().settings host = cfg.Server.host if host in ("0.0.0.0", "::"): try: with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s: s.settimeout(0.1) s.connect(("8.8.8.8", 80)) host = s.getsockname()[0] except OSError: host = "127.0.0.1" scheme = "https" if cfg.Server.enable_ssl else "http" return f"{scheme}://{host}:{cfg.Server.port}" # ── FastMCP Server ──────────────────────────────────────────────────── def _create_mcp_server() -> FastMCP: """Create MCP server with security settings from configuration.""" cfg = Config.instance().settings.Server # Always pass an explicit TransportSecuritySettings to prevent FastMCP # from auto-enabling protection when host is localhost (its default). if cfg.mcp_enable_dns_rebinding_protection: transport_security = TransportSecuritySettings( enable_dns_rebinding_protection=True, allowed_hosts=cfg.mcp_allowed_hosts or ["127.0.0.1:*", "localhost:*"], allowed_origins=cfg.mcp_allowed_origins or ["http://127.0.0.1:*", "http://localhost:*"], ) else: transport_security = TransportSecuritySettings( enable_dns_rebinding_protection=False, ) mcp = FastMCP("GNS3 MCP Server", transport_security=transport_security) return mcp mcp = _create_mcp_server() # ── Tool handlers ───────────────────────────────────────────────────── def _run_handler_sync(handler, params: dict[str, Any]) -> list[dict[str, Any]]: """Run a synchronous Gns3Connector handler in a thread.""" ctx = { "server_url": _server_url(), "jwt_token": _jwt_token_var.get(), } result = handler(params, ctx) return [{"type": "text", "text": json.dumps(result, ensure_ascii=False, default=str)}] @mcp.tool() async def list_projects() -> list[dict[str, Any]]: """List all GNS3 projects accessible to the current user.""" return await asyncio.to_thread(_run_handler_sync, list_projects_handler, {}) @mcp.tool() async def get_project( project_id: Annotated[str, Field(description="UUID of the project")], ) -> list[dict[str, Any]]: """Get detailed information about a specific project.""" return await asyncio.to_thread(_run_handler_sync, get_project_handler, {"project_id": project_id}) @mcp.tool() async def create_project( name: Annotated[str, Field(description="Project name")], description: Annotated[str, Field(description="Optional project description")] = "", ) -> list[dict[str, Any]]: """Create a new GNS3 project.""" params = {"name": name} if description: params["description"] = description return await asyncio.to_thread(_run_handler_sync, create_project_handler, params) @mcp.tool() async def delete_project( project_id: Annotated[str, Field(description="UUID of the project to delete")], ) -> list[dict[str, Any]]: """Delete a GNS3 project permanently.""" return await asyncio.to_thread(_run_handler_sync, delete_project_handler, {"project_id": project_id}) @mcp.tool() async def open_project( project_id: Annotated[str, Field(description="UUID of the project to open")], ) -> list[dict[str, Any]]: """Open a closed GNS3 project.""" return await asyncio.to_thread(_run_handler_sync, open_project_handler, {"project_id": project_id}) @mcp.tool() async def close_project( project_id: Annotated[str, Field(description="UUID of the project to close")], ) -> list[dict[str, Any]]: """Close an open GNS3 project.""" return await asyncio.to_thread(_run_handler_sync, close_project_handler, {"project_id": project_id}) @mcp.tool() async def get_project_stats( project_id: Annotated[str, Field(description="UUID of the project to get statistics for")], ) -> list[dict[str, Any]]: """Get statistics (nodes, links, snapshots, drawings) for a project.""" return await asyncio.to_thread(_run_handler_sync, get_project_stats_handler, {"project_id": project_id}) @mcp.tool() async def update_project( project_id: Annotated[str, Field(description="UUID of the project to update")], name: Annotated[str, Field(description="New project name")] = None, auto_close: Annotated[bool, Field(description="Close project when last client leaves")] = None, auto_open: Annotated[bool, Field(description="Project opens when GNS3 starts")] = None, auto_start: Annotated[bool, Field(description="Project starts when opened")] = None, scene_width: Annotated[int, Field(description="Width of the drawing area")] = None, scene_height: Annotated[int, Field(description="Height of the drawing area")] = None, zoom: Annotated[int, Field(description="Zoom of the drawing area")] = None, show_layers: Annotated[bool, Field(description="Show layers on the drawing area")] = None, snap_to_grid: Annotated[bool, Field(description="Snap to grid on the drawing area")] = None, show_grid: Annotated[bool, Field(description="Show the grid on the drawing area")] = None, grid_size: Annotated[int, Field(description="Grid size for the drawing area for nodes")] = None, drawing_grid_size: Annotated[int, Field(description="Grid size for the drawing area for drawings")] = None, show_interface_labels: Annotated[bool, Field(description="Show interface labels on the drawing area")] = None, ) -> list[dict[str, Any]]: """Update a project's properties (name, auto_close, auto_open, etc.).""" params = {"project_id": project_id} local_vars = { "name": name, "auto_close": auto_close, "auto_open": auto_open, "auto_start": auto_start, "scene_width": scene_width, "scene_height": scene_height, "zoom": zoom, "show_layers": show_layers, "snap_to_grid": snap_to_grid, "show_grid": show_grid, "grid_size": grid_size, "drawing_grid_size": drawing_grid_size, "show_interface_labels": show_interface_labels, } for key, val in local_vars.items(): if val is not None: params[key] = val return await asyncio.to_thread(_run_handler_sync, update_project_handler, params) @mcp.tool() async def duplicate_project( project_id: Annotated[str, Field(description="UUID of the project to duplicate")], name: Annotated[str, Field(description="New project name")], reset_mac_addresses: Annotated[bool, Field(description="Reset MAC addresses for this project")] = False, ) -> list[dict[str, Any]]: """Duplicate a project.""" params = {"project_id": project_id, "name": name} if reset_mac_addresses: params["reset_mac_addresses"] = reset_mac_addresses return await asyncio.to_thread(_run_handler_sync, duplicate_project_handler, params) @mcp.tool() async def get_project_readme( project_id: Annotated[str, Field(description="UUID of the project")], ) -> list[dict[str, Any]]: """Get the content of a project's README.md file — the project documentation (Markdown format).""" return await asyncio.to_thread(_run_handler_sync, get_project_readme_handler, {"project_id": project_id}) @mcp.tool() async def update_project_readme( project_id: Annotated[str, Field(description="UUID of the project")], content: Annotated[str, Field(description="Content to write to README.md (Markdown format)")], ) -> list[dict[str, Any]]: """Update or create a project's README.md file — the project documentation (Markdown format).""" return await asyncio.to_thread(_run_handler_sync, update_project_readme_handler, {"project_id": project_id, "content": content}) # ── Node tools ──────────────────────────────────────────────────────── @mcp.tool() async def get_nodes(project_id: str) -> list[dict[str, Any]]: """List all nodes in a project.""" return await asyncio.to_thread(_run_handler_sync, get_nodes_handler, {"project_id": project_id}) @mcp.tool() async def get_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node")], ) -> list[dict[str, Any]]: """Get detailed information about a specific node.""" return await asyncio.to_thread(_run_handler_sync, get_node_handler, {"project_id": project_id, "node_id": node_id}) @mcp.tool() async def start_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node to start")], ) -> list[dict[str, Any]]: """Start a node in a project.""" return await asyncio.to_thread(_run_handler_sync, start_node_handler, {"project_id": project_id, "node_id": node_id}) @mcp.tool() async def stop_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node to stop")], ) -> list[dict[str, Any]]: """Stop a node in a project.""" return await asyncio.to_thread(_run_handler_sync, stop_node_handler, {"project_id": project_id, "node_id": node_id}) @mcp.tool() async def reload_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node to reload")], ) -> list[dict[str, Any]]: """Reload (restart) a node in a project.""" return await asyncio.to_thread(_run_handler_sync, reload_node_handler, {"project_id": project_id, "node_id": node_id}) @mcp.tool() async def suspend_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node to suspend")], ) -> list[dict[str, Any]]: """Suspend a node in a project.""" return await asyncio.to_thread(_run_handler_sync, suspend_node_handler, {"project_id": project_id, "node_id": node_id}) @mcp.tool() async def create_node( project_id: Annotated[str, Field(description="UUID of the project")], template_id: Annotated[str, Field(description="UUID of the template to create the node from")], x: Annotated[int, Field(description="X coordinate on the project canvas")] = 0, y: Annotated[int, Field(description="Y coordinate on the project canvas")] = 0, compute_id: Annotated[str, Field(description="Compute ID (default: local)")] = "local", ) -> list[dict[str, Any]]: """Create a new node from a template in a project.""" return await asyncio.to_thread(_run_handler_sync, create_node_handler, { "project_id": project_id, "template_id": template_id, "x": x, "y": y, "compute_id": compute_id, }) @mcp.tool() async def delete_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node to delete")], ) -> list[dict[str, Any]]: """Delete a node from a project.""" return await asyncio.to_thread(_run_handler_sync, delete_node_handler, {"project_id": project_id, "node_id": node_id}) @mcp.tool() async def update_node( project_id: Annotated[str, Field(description="UUID of the project")], node_id: Annotated[str, Field(description="UUID of the node to update")], **kwargs: Any, ) -> list[dict[str, Any]]: """Update a node's properties (name, position, etc.).""" params = {"project_id": project_id, "node_id": node_id, **kwargs} return await asyncio.to_thread(_run_handler_sync, update_node_handler, params) @mcp.tool() async def get_node_console_info( project_id: Annotated[str, Field(description="UUID of the project containing the node")], node_id: Annotated[str, Field(description="UUID of the node to get console info for")], ) -> list[dict[str, Any]]: """Get WebSocket console connection info for a node. Returns the WebSocket URL, console type (telnet/ssh/vnc), and other connection details needed to interact with a node's console via WebSocket. Complete workflow: 1. Call this tool with project_id and node_id to get the WebSocket URL 2. Connect to the returned URL using websocat in text mode (-t): > websocat -t "ws://:3080/v3/projects/{project_id}/nodes/{node_id}/console/ws?token={jwt_token}" 3. Send device commands with \\r\\n line endings via heredoc: > websocat -t "ws://..." <<< $'\\r\\nenable\\r\\nshow version\\r\\nexit\\r\\n' 4. Receive response: websocat receives and displays device output Use 'timeout' to avoid connection hanging: > timeout 10 websocat -t "ws://..." <<< $'commands\\r\\n' Key points: - Use \\r\\n (not \\n) to match console protocol line endings - Use $'...' format for escape sequences in bash - Set a timeout to prevent hanging connections """ return await asyncio.to_thread(_run_handler_sync, get_node_console_info_handler, { "project_id": project_id, "node_id": node_id, }) # ── Link tools ──────────────────────────────────────────────────────── @mcp.tool() async def get_links(project_id: str) -> list[dict[str, Any]]: """List all links in a project.""" return await asyncio.to_thread(_run_handler_sync, get_links_handler, {"project_id": project_id}) @mcp.tool() async def get_link( project_id: Annotated[str, Field(description="UUID of the project")], link_id: Annotated[str, Field(description="UUID of the link")], ) -> list[dict[str, Any]]: """Get detailed information about a specific link.""" return await asyncio.to_thread(_run_handler_sync, get_link_handler, {"project_id": project_id, "link_id": link_id}) @mcp.tool() async def create_link( project_id: Annotated[str, Field(description="UUID of the project")], nodes: Annotated[list, Field(description="List of node connections, e.g. [{\"node_id\": \"...\", \"adapter_number\": 0, \"port_number\": 0}]")], link_type: Annotated[str, Field(description="Link type - ethernet or serial")] = "ethernet", filters: Annotated[dict, Field(description="Optional packet filters (must use array format): frequency_drop: [N], packet_loss: [rate], delay: [ms, jitter], corrupt: [rate], bpf: [expression]")] = None, ) -> list[dict[str, Any]]: """Create a link between two nodes in a project. Filters must use array format: - frequency_drop: [N] - Drop every Nth packet (N: -1 to 32767) - packet_loss: [rate] - Packet loss percentage (rate: 0 to 100) - delay: [ms, jitter] - Latency and jitter in milliseconds - corrupt: [rate] - Packet corruption percentage (rate: 0 to 100) - bpf: [expression] - Berkeley Packet Filter expression Example: {"filters": {"delay": [100, 10], "packet_loss": [5]}} """ params = {"project_id": project_id, "nodes": nodes, "link_type": link_type} if filters: params["filters"] = filters return await asyncio.to_thread(_run_handler_sync, create_link_handler, params) @mcp.tool() async def delete_link( project_id: Annotated[str, Field(description="UUID of the project")], link_id: Annotated[str, Field(description="UUID of the link to delete")], ) -> list[dict[str, Any]]: """Delete a link from a project.""" return await asyncio.to_thread(_run_handler_sync, delete_link_handler, {"project_id": project_id, "link_id": link_id}) @mcp.tool() async def update_link( project_id: Annotated[str, Field(description="UUID of the project")], link_id: Annotated[str, Field(description="UUID of the link to update")], **kwargs: Any, ) -> list[dict[str, Any]]: """Update a link's properties (suspend, filters, etc.). Supported kwargs: - suspend: boolean - Suspend or resume the link - filters: dict - Packet filters (must use array format): * frequency_drop: [N] - Drop every Nth packet (N: -1 to 32767) * packet_loss: [rate] - Packet loss percentage (rate: 0 to 100) * delay: [ms, jitter] - Latency and jitter in milliseconds * corrupt: [rate] - Packet corruption percentage (rate: 0 to 100) * bpf: [expression] - Berkeley Packet Filter expression Example filters: {"filters": {"frequency_drop": [10]}} {"filters": {"delay": [100, 10]}} {"filters": {"packet_loss": [5]}} {"filters": {"delay": [50, 5], "packet_loss": [2]}} """ params = {"project_id": project_id, "link_id": link_id, **kwargs} return await asyncio.to_thread(_run_handler_sync, update_link_handler, params) # ── Template tools ──────────────────────────────────────────────────── @mcp.tool() async def list_templates() -> list[dict[str, Any]]: """List all available templates on the server.""" return await asyncio.to_thread(_run_handler_sync, list_templates_handler, {}) @mcp.tool() async def get_template( template_id: Annotated[str | None, Field(description="Template UUID (optional if name is provided)")] = None, name: Annotated[str | None, Field(description="Template name (optional if template_id is provided)")] = None, ) -> list[dict[str, Any]]: """Get detailed information about a specific template.""" return await asyncio.to_thread(_run_handler_sync, get_template_handler, { "template_id": template_id, "name": name, }) @mcp.tool() async def create_template( name: Annotated[str, Field(description="Template name")], template_type: Annotated[str, Field(description="Template type (e.g. qemu, docker, dynamips)")], compute_id: Annotated[str, Field(description="Compute ID (default: local)")] = "local", ) -> list[dict[str, Any]]: """Create a new template.""" return await asyncio.to_thread(_run_handler_sync, create_template_handler, { "name": name, "template_type": template_type, "compute_id": compute_id, }) @mcp.tool() async def update_template( template_id: Annotated[str | None, Field(description="Template UUID (optional if name is provided)")] = None, name: Annotated[str | None, Field(description="Template name (optional if template_id is provided)")] = None, **kwargs: Any, ) -> list[dict[str, Any]]: """Update an existing template's properties.""" params = {"template_id": template_id, "name": name, **kwargs} return await asyncio.to_thread(_run_handler_sync, update_template_handler, params) @mcp.tool() async def delete_template( template_id: Annotated[str | None, Field(description="Template UUID (optional if name is provided)")] = None, name: Annotated[str | None, Field(description="Template name (optional if template_id is provided)")] = None, ) -> list[dict[str, Any]]: """Delete a template.""" return await asyncio.to_thread(_run_handler_sync, delete_template_handler, { "template_id": template_id, "name": name, }) # ── Compute tools ───────────────────────────────────────────────────── @mcp.tool() async def list_computes() -> list[dict[str, Any]]: """List all compute nodes available to the server.""" return await asyncio.to_thread(_run_handler_sync, list_computes_handler, {}) @mcp.tool() async def get_compute( compute_id: Annotated[str, Field(description="Compute ID (default: local)")] = "local", ) -> list[dict[str, Any]]: """Get detailed information about a compute node.""" return await asyncio.to_thread(_run_handler_sync, get_compute_handler, {"compute_id": compute_id}) @mcp.tool() async def get_compute_images( emulator: Annotated[str, Field(description="Emulator type (e.g. qemu, iou, docker)")], compute_id: Annotated[str, Field(description="Compute ID (default: local)")] = "local", ) -> list[dict[str, Any]]: """List available images for an emulator on a compute node.""" return await asyncio.to_thread(_run_handler_sync, get_compute_images_handler, { "emulator": emulator, "compute_id": compute_id, }) # ── Auth‑wrapped SSE app ────────────────────────────────────────────── def _make_auth_wrapper(inner_app): """Wrap the SSE app with JWT validation. Supports two ways to pass the token (checked in order): 1. Authorization: Bearer header 2. ?token= query parameter POST messages are passed through (authenticated by their session). """ async def auth_wrapper(scope, receive, send): # Wait for GNS3 server to complete initialization before accepting MCP connections server_ready = await wait_for_mcp_ready() if not server_ready: # Server initialization timed out - return 503 Service Unavailable client_info = extract_client_info(scope, auth_service) log.warning( f"Rejecting MCP connection - GNS3 server initialization not complete. " f"Client: {client_info['host']}:{client_info['port']} ({client_info['user_info']}, Path: {client_info['path']})" ) response = Response( "GNS3 server initialization not complete - please retry later", status_code=503 ) await response(scope, receive, send) return if scope["type"] == "http" and scope["method"] == "GET": token = None headers = dict(scope.get("headers", [])) auth = headers.get(b"authorization", b"").decode() if auth.startswith("Bearer "): token = auth[7:] if not token: params = parse_qs(scope.get("query_string", b"").decode()) tokens = params.get("token", []) if tokens: token = tokens[0] if not token or not await _validate_token(token): response = Response("Missing or invalid token", status_code=401) await response(scope, receive, send) return _jwt_token_var.set(token) await inner_app(scope, receive, send) return auth_wrapper # ── FastAPI router ──────────────────────────────────────────────────── router = APIRouter(prefix="/mcp", tags=["MCP"]) @router.get("/") async def mcp_root(): """MCP service metadata.""" return { "name": "GNS3 MCP Server", "version": "1.0.0", "authentication": ["Authorization: Bearer ", "?token="], "transports": { "sse": "/v3/mcp/transport/sse", }, } def register_starlette_routes(app): """Mount MCP transports on the FastAPI app.""" sse_app = _make_auth_wrapper(mcp.sse_app(mount_path="")) app.mount("/v3/mcp/transport", sse_app, name="mcp-sse") log.info("MCP SSE server mounted at /v3/mcp/transport")