cwebsocket

A portable, high-performance WebSocket client library written in C, designed for embedded systems and production environments.

Features

WebSocket Protocol (RFC 6455)

Complete implementation of the WebSocket protocol with 100% Autobahn test suite compliance.

• Binary and text frame support
• Fragmentation and control frames (ping/pong/close)
• SSL/TLS support (wss://)
• Permessage-deflate compression
• Multi-threaded client support
• UTF-8 validation with overlong encoding detection

Subprotocols

Echo - Simple echo subprotocol for testing and examples

STOMP 1.2 - Streaming Text Oriented Messaging Protocol

• Frame encoding and decoding
• Header processing
• Binary message support

MQTT 5.0 - Message Queuing Telemetry Transport with enhanced authentication

• All packet types (CONNECT, PUBLISH, SUBSCRIBE, PUBACK, PUBREC, PUBREL, PUBCOMP, DISCONNECT, AUTH)
• QoS levels 0, 1, and 2
• Retained messages
• Topic aliases for bandwidth optimization
• SCRAM-SHA-256 enhanced authentication (RFC 5802/7677)
• Subscription options
• Keep-alive with automatic PINGREQ/PINGRESP
• Session persistence
• Flow control and packet ID management
• Property system (38 property types)

Building

Dependencies: autoconf, automake, libtool, libssl-dev, zlib1g-dev

./autogen.sh
./configure
make
sudo make install

Build options:

./configure --enable-threads=no   # Disable multi-threading
./configure --enable-ssl=no       # Disable SSL/TLS support

Usage

WebSocket Client

./websocket-client wss://echo.websocket.org

STOMP Client

./stomp-client ws://localhost:61614

MQTT Client

./mqtt-client ws://localhost:8083/mqtt

Testing

Run unit tests:

make test

Run integration tests:

make test-integration

Component-specific tests:

make test-websocket     # WebSocket unit and integration tests
make test-stomp         # STOMP integration tests
make test-mqtt          # MQTT unit and integration tests
make test-mqtt-auth     # MQTT SCRAM-SHA-256 authentication tests

Quality assurance:

make qa                 # Run full QA suite (build, test, valgrind, static analysis, security scan)
make valgrind           # Memory leak detection
make static-analysis    # cppcheck analysis
make security-scan      # flawfinder security scan

Support

Please consider supporting this project for ongoing success and sustainability. I'm a passionate open source contributor making a professional living creating free, secure, scalable, robust, enterprise grade, distributed systems and cloud native solutions.

I'm also available for international consulting opportunities. Please let me know how I can assist you or your organization in achieving your desired security posture and technology goals.

https://github.com/sponsors/jeremyhahn

https://www.linkedin.com/in/jeremyhahn