httpd_sess_process() function

Server instance data

Session

Retrieve a session by its descriptor

Enumerates all sessions

Remove client descriptor from the session / socket database and close the connection for this client.

Checks if session can accept another connection from new client. If sockets database is full then this returns false.

Returns next free session slot (fd<0)

Delete sessions whose FDs have became invalid. This is a recovery strategy e.g. after select() fails.

Initializes an http session by resetting the sockets database.

Starts a new session for client requesting connection and adds it's descriptor to the socket database.

Add descriptors present in the socket database to an fdset and update the value of maxfd which are needed by the select function for looking through all available sockets for incoming data.

Checks if session has any pending data/packets for processing This is needed as httpd_unrecv may un-receive next packet in the stream. If only partial packet was received then select() would mark the fd for processing as remaining part of the packet would still be in socket recv queue. But if a complete packet got unreceived then it would not be processed until further data is received on the socket. This is when this function comes in use, as it checks the socket's pending data buffer.

Removes the least recently used client from the session This may be useful if new clients are requesting for connection but max number of connections is reached, in which case the client which is inactive for the longest will be removed from the session.

Closes all sessions

For an HTTP request, searches through all the registered URI handlers and invokes the appropriate one if found

Unregister all URI handlers

Initiates the processing of HTTP request Receives incoming TCP packet on a socket, then parses the packet as HTTP request and fills httpd_req_t data structure with the extracted URI, headers are ready to be fetched from scratch buffer and calling http_recv() after this reads the body of the request.

For an HTTP request, resets the resources allocated for it and purges any data left to be received