Implementation and example of WebSocket (and simple HTTP) servers for ESP8266 microcontrollers in native C SDK from Espressif.
Server functions are declared in http.h file along with HTTP server and defined in http.c file.
void http_start(int16_t port)Starts HTTP and WebSocket server listening on the port.
void ICACHE_FLASH_ATTR websocket_set_receive_callback(ws_receive_callback_t callback);Users can define their own receive callback that gets called when websocket received new data. Callback must be of void type.
Callbacks parameters are:
struct espconn *con - with is current connection that sent data, char *data - pointer to the data and uint64_t length - length of that data.
Example of receive callback is presented here: src/main.c.
void websocket_write(struct espconn *con, const void *data, uint64_t len, uint8_t mode);Writes data for specified connection con of length len in websocket mode. Available modes are:
WEBSOCKET_BIN - for binary data
WEBSOCKET_TEXT - for strings
void websocket_write_all(const void *data, uint64_t len, uint8_t mode);Writes to all websocket clients existing in the connections pool. Parameters are the same as for websocket_write.
struct espconn **websocket_get_connections();Returns espconn connections of websockets in the pool. This is not equal to all espconn connections made to the server or even all websocket clients, but only pool of clients that we can send data spontaneously. We can still respond to every connected client via receive callback.
void websocket_close(struct espconn *con);Closes connection to websocket and removes it from the pool.
char *websocket_get_accept(char *key);Generates Sec-WebSocket-Accept key based on key Sec-WebSocket-Key sent by the client and WEBSOCKET_MAGIC.
void websocket_add_connection(struct espconn *con);Sets espconn connection parameters (such as KEEPALIVE and NODELAY) and adds connection to websocket pool connection.
char *websocket_decode(char *pdata, unsigned short len);Unmasks data received from websocket.
void websocket_receive(void *arg, char *pdata, unsigned short len);Gets called when raw data is received from websocket connection.
Project consist of example web page and JS script and main function that sends voltage on ADC every few seconds to all websockets in pool.
Published under MIT license.
Copyright (c) 2018 Kacper Zybała
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