open_fn() was introduced in the context of HTTPS server, as a configurable callback function that is called by the HTTP server, on every newly created socket. It is responsible of allocating resources for per session transport security.
Earlier, if open_fn were to fail, the newly created socket would be closed by the server but the corresponding entry, for the now invalid socket, will remain in the internal socket database until that invalid socket is detected due to error when calling select(). Because of this delayed closing of sockets, the HTTPS server would quickly face shortage of available sessions when a lot of SSL handshake errors are happening (this typically occurs when a browser finds that the server certificate is self signed). This changes in this MR fix this issue by clearing up the socket from internal database, right after open_fn fails.
Closes https://github.com/espressif/esp-idf/issues/3479
* http_sess_set_*_override APIs are now the only ones available to set custom recv/send/pending functions
* Fixed side effects to using http_sess_set/get_context inside URI handlers
Changes:
- renamed `httpd_free_sess_ctx_fn_t` to `httpd_free_ctx_fn_t`
- added a `httpd_handle_t` argument to `httpd_send_func_t` and `httpd_recv_func_t`
- internal function `httpd_sess_get()` is no longer static, as it's used in other
files besides httpd_sess.c
Bug fixes:
- removed a trailing semicolon from `HTTPD_DEFAULT_CONFIG()`
- fixed issue with failed `select()`, now it automatically closes invalid sockets
instead of shutting down the entire server
New features:
- `httpd_resp_send()` and `httpd_resp_send_chunk()` now accept -1 as length to use
`strlen()` internally
- added `httpd_sess_set_ctx()` to accompany `httpd_sess_get_ctx()`
- added a "transport context" to the session structure (next to user context)
- added `httpd_sess_{get,set}_transport_ctx()` to work with this transport context
- added "global user context" and "global transport context" stored in the server
config (and then the handle); supports a user-provided free_fn
- added a "pending func" to e.g. check for data in the transport layer receive
buffer
- added functions `httpd_set_sess_{send,recv,pending}_override()` that target
a session by ID (i.e. not using a request object)
- added `httpd_set_pending_override()`
- added a "open_fn" and "close_fn" - functions called when creating and closing
a session. These may be used to set up transport layer encryption or some other
session-wide feature
