libuv WebSocket

this will eventually be a websocket server library and set of tools for building fast and small websocket servers in c using the wonderful libuv. the goal is to be very small and very fast and leave most of the decisions to the user of the library

Proposed API

• sha1.h - function to calculate SHA1 hash of a buffer
• wsparser.h - functions for parsing websocket frames
• websock.h - functions for running websocket servers

Building

git clone [email protected]:billywhizz/ws-uv.git
cd ws-uv
git submodule init
git submodule update
make -j 4

Running

the websock server will listen on port 80. see main in websocket.c for setup

./websock

Features

• supports parsing of all websocket control and data frames from a stream
• evented io handled by libuv
• does not support HTTP beyond what is required for performing a websocket handshake
• should be pretty straightforward to build on windows/mac. if anyone feels like contributing patches for this, please feel free
• no plans to add SSL support. if you want to do ssl then put something in front of this
• zero dependencies. libuv and http-parser are statically linked into the websocket library
• at startup only consumes 600KB of RAM on linux
• very small overhead per connection (need to measure)
• handshake performed using joyent http-parser which is very low overhead and fast
• only supports http://tools.ietf.org/html/rfc6455. is not backwards compatible
• only low level support - hands off messages to user. does not react to control messages or perform any logic around fragmented messages
• does not do any utf8 decoding for text frames. chunks of frame payloads are returned as pointers to char buffers whether they are binary or text

Future

• support pausing of parser
• !!!!handle overflows on headers and header sizes!!!!
• allow user definable limits on headers and header sizes
• allow configuration of port, tcp backlog, nodelay, keepalive, connection limits, bandwidth throttling,
• daemonization
• cluster support by receiving socket on stdin/pipe
• support quitting parser execution with return values from callbacks
• no plans to add SSL support. if you want to do ssl then put something in front of this
• websocket extension support
• higher level api to deal with control frames and fragmented messages
• possibly add support for static file serving and http user modules
• SPDY support? do we really want to do ssl?
• possibly add fastcgi and memcached protocol support
• thread safety
• node.js scripts for benchmarking
• tests
• benchmarks
• improve the make file to build and run tests
• windows/mac support
• clean and small websocket api for servers and clients
• easy to hook into server for running websocket applications
• user supplied c scripts (llvm)
• defined interface for libraries that can be loaded at runtime
• user scripts are written in c and can be compiled and run on the fly by the server (llvm)

Usage

Parser:

see test-parser.c for usage of the parser

// websocket message struct
struct ws_header {
  uint8_t fin;
  uint8_t reserved[3];
  uint8_t opcode;
  uint32_t length;
  uint8_t mask;
  uint8_t maskkey[4];
};

// callbacks for parser

// this is called when a websocket frame header has been parsed
int on_header(ws_parser* p);
// this is called for each chunk of the body of a frame received. it
// is up to the callee to manage assembly of message bodies
int on_chunk(ws_parser* p, const char* at, size_t len);
// called when a frame is complete
int on_complete(ws_parser* p);

// allocate a new parser
ws_parser* parser = malloc(sizeof(ws_parser));
// allocate a settings structure
ws_settings* settings = malloc(sizeof(ws_settings));
// set callbacks for parser
settings->on_header = &on_header;
settings->on_chunk = &on_chunk;
settings->on_complete = &on_complete;
// initialise the parser. you should call this if you are reusing a parser
// across multiple connections
ws_init(parser);
// execute the parser with 
ws_execute(parser, settings, buffer, 0, sizeof(login));