Lightweight MCP Server in C

This repository contains a lightweight Model Context Protocol (MCP) server integrated directly into ovs-vswitchd.

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Module 1 & 2 - Basic MCP Server Integration

Files Added

• vswitchd/mcp_server.c
• vswitchd/mcp_server.h

Files Modified

• vswitchd/ovs-vswitchd.c
  • Called mcp_server_init() during startup.
  • Called mcp_server_run() inside the main loop.
  • Called mcp_server_close() during shutdown.
• vswitchd/automake.mk
  • Added mcp_server.c to build sources.

Functionality

• Server Port: 8080
• Endpoint: POST /mcp
• Response: {"status": "ok"}

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Module 3 - MCP Tool Routing and Hardening

Files Modified

• vswitchd/mcp_server.c

  • Added HTTP request parsing and JSON dispatcher so MCP calls can route to real tool handlers.
  • Added non-blocking socket handling and mcp_server_wait() polling so ovs-vswitchd stays responsive.
  • Added Content-Length validation and request-size checks so malformed or incomplete requests are handled safely.
  • Switched startup and shutdown logs to OVS VLOG style so runtime logs are consistent with the rest of OVS.

• vswitchd/mcp_server.h

  • Added mcp_server_wait() declaration so the main loop can register MCP socket wakeups.

• vswitchd/ovs-vswitchd.c

  • Hooked mcp_server_wait() into the wait phase so incoming MCP traffic wakes the poll loop correctly.

• vswitchd/bridge.h

  • Added MCP bridge handler APIs so request dispatch can call bridge data collectors directly.

• vswitchd/bridge.c

  • Implemented handlers for switch.get_ports, switch.get_flows, and switch.get_port_stats so MCP returns useful switch data.

• restart.sh

  • Simplified to incremental build, install, and restart flow so day-to-day development is faster.

• build.sh

  • Kept a full bootstrap path so a clean rebuild remains one command when needed.

• Makefile.am

  • Added helper scripts to EXTRA_DIST so dist checks pass when scripts are tracked in Git.

Functionality

• Supported MCP Tools: switch.get_ports, switch.get_flows, switch.get_port_stats
• Request Safety: method and path checks, JSON validation, content-length validation, max request-size guard
• Response Style: structured JSON success and error responses for easier debugging and integration

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Setup and Run

Build OVS

./boot.sh
./configure
make -j"$(nproc)"

sudo make install

Start OVS

Start database server:

sudo ovsdb-server \
  --remote=punix:/usr/local/var/run/openvswitch/db.sock \
  --remote=db:Open_vSwitch,Open_vSwitch,manager_options \
  --pidfile --detach

Initialize DB:

sudo ovs-vsctl --no-wait init

Start switch daemon:

sudo ovs-vswitchd --pidfile --detach

Testing the MCP API

To set the VLAN tag to 100:

curl -X POST -H "Content-Type: application/json" \
  -d '{"id": "1", "tool": "switch.set_vlan", "arguments": {"bridge": "br0", "port": "br0", "vlan": 100}}' \
  http://localhost:8080/mcp

Verify tag is set:

sudo ovs-vsctl get port br0 tag

AI Assistant Chat

Configure your API Key and choice of model inside .env:

GEMINI_API_KEY="AQ.your-key-here"
GEMINI_MODEL="gemini-3.1-flash-lite"

Start the interactive chat interface:

make chat