libwebsocket_create_server - Create the listening websockets server

int libwebsocket_create_server (int port, int (*callback) (struct libwebsocket *, enum libwebsocket_callback_reasons, void *, void *, size_t), int protocol, size_t user_area_size, const char * ssl_cert_filepath, const char * ssl_private_key_filepath, int gid, int uid)

Arguments

port: Port to listen on
callback: The callback in user code to perform actual serving
protocol: Which version of the websockets protocol (currently 76)
user_area_size: How much memory to allocate per connection session which will be used by the user application to store per-session data. A pointer to this space is given when the user callback is called.
ssl_cert_filepath: If libwebsockets was compiled to use ssl, and you want to listen using SSL, set to the filepath to fetch the server cert from, otherwise NULL for unencrypted
ssl_private_key_filepath: filepath to private key if wanting SSL mode, else ignored
gid: group id to change to after setting listen socket, or -1.
uid: user id to change to after setting listen socket, or -1.

Description

This function forks to create the listening socket and takes care of all initialization in one step.
The callback function is called for a handful of events including http requests coming in, websocket connections becoming established, and data arriving; it's also called periodically to allow async transmission.
The server created is a simple http server by default; part of the websocket standard is upgrading this http connection to a websocket one.
This allows the same server to provide files like scripts and favicon / images or whatever over http and dynamic data over websockets all in one place; they're all handled in the user callback.

libwebsocket_get_uri - Return the URI path being requested

const char * libwebsocket_get_uri (struct libwebsocket * wsi)

Arguments

wsi: Websocket instance

Description

The user code can find out the local path being opened from this call, it's valid on HTTP or established websocket connections. If the client opened the connection with "http://127.0.0.1/xyz/abc.d" then this call will return a pointer to "/xyz/abc.d"

libwebsocket_write - Apply protocol then write data to client

int libwebsocket_write (struct libwebsocket * wsi, unsigned char * buf, size_t len, enum libwebsocket_write_protocol protocol)

Arguments

wsi: Websocket instance (available from user callback)
buf: The data to send. For data being sent on a websocket connection (ie, not default http), this buffer MUST have LWS_SEND_BUFFER_PRE_PADDING bytes valid BEFORE the pointer and an additional LWS_SEND_BUFFER_POST_PADDING bytes valid in the buffer after (buf + len). This is so the protocol header and trailer data can be added in-situ.
len: Count of the data bytes in the payload starting from buf
protocol: Use LWS_WRITE_HTTP to reply to an http connection, and one of LWS_WRITE_BINARY or LWS_WRITE_TEXT to send appropriate data on a websockets connection. Remember to allow the extra bytes before and after buf if LWS_WRITE_BINARY or LWS_WRITE_TEXT are used.

Description

This function provides the way to issue data back to the client for both http and websocket protocols.
In the case of sending using websocket protocol, be sure to allocate valid storage before and after buf as explained above. This scheme allows maximum efficiency of sending data and protocol in a single packet while not burdening the user code with any protocol knowledge.

libwebsockets_serve_http_file - Send a file back to the client using http

int libwebsockets_serve_http_file (struct libwebsocket * wsi, const char * file, const char * content_type)

Arguments

wsi: Websocket instance (available from user callback)
file: The file to issue over http
content_type: The http content type, eg, text/html

Description

This function is intended to be called from the callback in response to http requests from the client. It allows the callback to issue local files down the http link in a single step.