mongoose/docs/http/events.md

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HTTP events

As discussed in the overview, mg_set_protocol_http_websocket() function parses incoming data, treats it as HTTP or WebSocket, and triggers high-level HTTP or WebSocket events. Here is a list of events specific to HTTP.

• MG_EV_HTTP_REQUEST: An HTTP request has arrived. Parsed request is passed as struct http_message through the handler's void *ev_data pointer.
• MG_EV_HTTP_REPLY: An HTTP reply has arrived. Parsed reply is passed as struct http_message through the handler's void *ev_data pointer.
• MG_EV_HTTP_MULTIPART_REQUEST: A multipart POST request has arrived. This event is sent before body is parsed. After this, the user should expect a sequence of MG_EV_HTTP_PART_BEGIN/DATA/END requests. This is also the last time when headers and other request fields are accessible.
• MG_EV_HTTP_CHUNK: An 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. The 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_HTTP_PART_BEGIN: a new part of multipart message is started, extra parameters are passed in mg_http_multipart_part
• MG_EV_HTTP_PART_DATA: a new portion of data from the multiparted message no additional headers are available, only data and data size
• MG_EV_HTTP_PART_END: a final boundary received, analogue to maybe used to find the end of packet Note: Mongoose should be compiled with MG_ENABLE_HTTP_STREAMING_MULTIPART to enable multipart events.