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#
# 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 <http://www.gnu.org/licenses/>.
"""
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
from typing import Any
from urllib.parse import parse_qs
from fastapi import APIRouter
from fastapi.responses import Response
from mcp.server.fastmcp import FastMCP
from gns3server.config import Config
from gns3server.services import auth_service
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,
)
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__)
# ── Perconnection 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 == "0.0.0.0":
host = "127.0.0.1"
scheme = "https" if cfg.Server.enable_ssl else "http"
return f"{scheme}://{host}:{cfg.Server.port}"
# ── FastMCP Server ────────────────────────────────────────────────────
mcp = FastMCP("GNS3 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: str) -> list[dict[str, Any]]:
"""Get detailed information about a specific project.
Args:
project_id: Project UUID
"""
return await asyncio.to_thread(_run_handler_sync, get_project_handler, {"project_id": project_id})
@mcp.tool()
async def create_project(name: str, description: str = "") -> list[dict[str, Any]]:
"""Create a new GNS3 project.
Args:
name: Project name
description: Optional project description
"""
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: str) -> list[dict[str, Any]]:
"""Delete a GNS3 project permanently.
Args:
project_id: UUID of the project to delete
"""
return await asyncio.to_thread(_run_handler_sync, delete_project_handler, {"project_id": project_id})
@mcp.tool()
async def open_project(project_id: str) -> list[dict[str, Any]]:
"""Open a closed GNS3 project.
Args:
project_id: Project UUID
"""
return await asyncio.to_thread(_run_handler_sync, open_project_handler, {"project_id": project_id})
@mcp.tool()
async def close_project(project_id: str) -> list[dict[str, Any]]:
"""Close an open GNS3 project.
Args:
project_id: Project UUID
"""
return await asyncio.to_thread(_run_handler_sync, close_project_handler, {"project_id": project_id})
@mcp.tool()
async def get_project_stats(project_id: str) -> list[dict[str, Any]]:
"""Get statistics (nodes, links, snapshots, drawings) for a project.
Args:
project_id: Project UUID
"""
return await asyncio.to_thread(_run_handler_sync, get_project_stats_handler, {"project_id": project_id})
# ── 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: str, node_id: str) -> list[dict[str, Any]]:
"""Get detailed information about a specific node.
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, node_id: str) -> list[dict[str, Any]]:
"""Start a node in a project.
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, node_id: str) -> list[dict[str, Any]]:
"""Stop a node in a project.
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, node_id: str) -> list[dict[str, Any]]:
"""Reload (restart) a node in a project.
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, node_id: str) -> list[dict[str, Any]]:
"""Suspend a node in a project.
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, template_id: str, x: int = 0, y: int = 0, compute_id: str = "local") -> list[dict[str, Any]]:
"""Create a new node from a template in a project.
Args:
project_id: Project UUID
template_id: Template UUID
x: X coordinate (optional)
y: Y coordinate (optional)
compute_id: Compute ID (optional, default: local)
"""
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: str, node_id: str) -> list[dict[str, Any]]:
"""Delete a node from a project.
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, node_id: str, **kwargs: Any) -> list[dict[str, Any]]:
"""Update a node's properties (name, position, etc.).
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, node_id: str) -> list[dict[str, Any]]:
"""Get console WebSocket URL for a node (use websocat to connect).
Args:
project_id: Project UUID
node_id: Node UUID
"""
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: str, link_id: str) -> list[dict[str, Any]]:
"""Get detailed information about a specific link.
Args:
project_id: Project UUID
link_id: Link UUID
"""
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: str, nodes: list, link_type: str = "ethernet", filters: dict = None) -> list[dict[str, Any]]:
"""Create a link between two nodes in a project.
Args:
project_id: Project UUID
nodes: List of node connections, e.g. [{"node_id": "...", "adapter_number": 0, "port_number": 0}, ...]
link_type: Link type - ethernet or serial (optional)
filters: Packet filters (optional)
"""
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: str, link_id: str) -> list[dict[str, Any]]:
"""Delete a link from a project.
Args:
project_id: Project UUID
link_id: Link UUID
"""
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: str, link_id: str, **kwargs: Any) -> list[dict[str, Any]]:
"""Update a link's properties (suspend, filters, etc.).
Args:
project_id: Project UUID
link_id: Link UUID
"""
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: str = None, name: str = None) -> list[dict[str, Any]]:
"""Get detailed information about a specific template.
Args:
template_id: Template UUID (optional if name is provided)
name: Template name (optional if template_id is provided)
"""
return await asyncio.to_thread(_run_handler_sync, get_template_handler, {
"template_id": template_id, "name": name,
})
@mcp.tool()
async def create_template(name: str, template_type: str, compute_id: str = "local") -> list[dict[str, Any]]:
"""Create a new template.
Args:
name: Template name
template_type: Template type (e.g. qemu, docker, dynamips)
compute_id: Compute ID (optional, default: local)
"""
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: str = None, name: str = None, **kwargs: Any) -> list[dict[str, Any]]:
"""Update an existing template's properties.
Args:
template_id: Template UUID (optional if name is provided)
name: Template name (optional if template_id is provided)
"""
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: str = None, name: str = None) -> list[dict[str, Any]]:
"""Delete a template.
Args:
template_id: Template UUID (optional if name is provided)
name: Template name (optional if template_id is provided)
"""
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: str = "local") -> list[dict[str, Any]]:
"""Get detailed information about a compute node.
Args:
compute_id: Compute ID (default: local)
"""
return await asyncio.to_thread(_run_handler_sync, get_compute_handler, {"compute_id": compute_id})
@mcp.tool()
async def get_compute_images(emulator: str, compute_id: str = "local") -> list[dict[str, Any]]:
"""List available images for an emulator on a compute node.
Args:
emulator: Emulator type (e.g. qemu, iou, docker)
compute_id: Compute ID (default: local)
"""
return await asyncio.to_thread(_run_handler_sync, get_compute_images_handler, {
"emulator": emulator, "compute_id": compute_id,
})
# ── Authwrapped 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 <jwt> header
2. ?token=<jwt> query parameter
POST messages are passed through (authenticated by their session).
"""
async def auth_wrapper(scope, receive, send):
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 <jwt>", "?token=<jwt>"],
"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")