mongoose/docs/c-api/http.h/mg_set_protocol_http_websocket.md

title	decl_name	symbol_kind	signature
mg_set_protocol_http_websocket()	mg_set_protocol_http_websocket	func	void mg_set_protocol_http_websocket(struct mg_connection *nc);

Attaches a built-in HTTP event handler to the given connection. The user-defined event handler will receive following extra events:

• MG_EV_HTTP_REQUEST: HTTP request has arrived. Parsed HTTP request is passed as struct http_message through the handler's void *ev_data pointer.
• MG_EV_HTTP_REPLY: The HTTP reply has arrived. The parsed HTTP reply is passed as struct http_message through the handler's void *ev_data pointer.
• MG_EV_HTTP_CHUNK: The HTTP chunked-encoding chunk has arrived. The parsed HTTP reply is passed as struct http_message through the handler's void *ev_data pointer. http_message::body would contain incomplete, reassembled HTTP body. It will grow with every new chunk that arrives, and it can potentially consume a lot of memory. An event handler may process the body as chunks are coming, and signal Mongoose to delete processed body by setting MG_F_DELETE_CHUNK in mg_connection::flags. When the last zero chunk is received, Mongoose sends MG_EV_HTTP_REPLY event with full reassembled body (if handler did not signal to delete chunks) or with empty body (if handler did signal to delete chunks).
• MG_EV_WEBSOCKET_HANDSHAKE_REQUEST: server has received the WebSocket handshake request. ev_data contains parsed HTTP request.
• MG_EV_WEBSOCKET_HANDSHAKE_DONE: server has completed the WebSocket handshake. ev_data is NULL.
• MG_EV_WEBSOCKET_FRAME: new WebSocket frame has arrived. ev_data is struct websocket_message *

When compiled with MG_ENABLE_HTTP_STREAMING_MULTIPART, Mongoose parses multipart requests and splits them into separate events:

• MG_EV_HTTP_MULTIPART_REQUEST: Start of the request. This event is sent before body is parsed. After this, the user should expect a sequence of PART_BEGIN/DATA/END requests. This is also the last time when headers and other request fields are accessible.
• MG_EV_HTTP_PART_BEGIN: Start of a part of a multipart message. Argument: mg_http_multipart_part with var_name and file_name set (if present). No data is passed in this message.
• MG_EV_HTTP_PART_DATA: new portion of data from the multipart message. Argument: mg_http_multipart_part. var_name and file_name are preserved, data is available in mg_http_multipart_part.data.
• MG_EV_HTTP_PART_END: End of the current part. var_name, file_name are the same, no data in the message. If status is 0, then the part is properly terminated with a boundary, status < 0 means that connection was terminated.
• MG_EV_HTTP_MULTIPART_REQUEST_END: End of the multipart request. Argument: mg_http_multipart_part, var_name and file_name are NULL, status = 0 means request was properly closed, < 0 means connection was terminated (note: in this case both PART_END and REQUEST_END are delivered).