WebSockets server implementation for Raspberry Pi Pico W on top of raw lwIP
Users of this library must provide a CMake library named lwipopts_provider which provides the lwipopts.h header for lwIP configuration.
Users must also link this library with an implementation of pico_cyw43_arch (e.g. pico_cyw43_arch_lwip_poll).
Warning: the pico_cyw43_arch implementation must allow standard library functions (including malloc/free) to be called from network workers. Since pico_cyw43_arch_lwip_threadsafe_background executes workers within ISRs, it is typically not safe unless you have added a critical section
wrapper around malloc and friends.
This server does not currently support HTTPS/WSS
This does not aim to be a general-purpose HTTP server, and only includes minimal HTTP support for the WebSocket handshake. Only GET / HTTP/1.1 requests are allowed, all other requests will return status 400/404/405.
Valid requests which do not request a WebSocket upgrade will be served a static HTML blob. This is defined at compile time via CMake, using the specified file (see example). Define STATIC_HTML_PATH to point at the directory containing the static HTML, and STATIC_HTML_FILENAME as the static HTML filename. Changes to the HTML file will get added at compile time.
No benchmarking has been done, but this server is expected to have a small memory footprint and low response latency. However, there is likely room for performance improvement when it comes to processing large payloads.
Some low hanging fruit for future improvement:
- Process payload bytes in bulk
- Provide interface to consume chunked messages, without copying into a continuous buffer