Handlers

The handlers are functions that are responsible for specific operations in the application. A handler could be invoked as a result of an event in the ICQ network or as a result of a user request. The handlers are implemented in the files:

• handlers.h
• handlers.c

The description above gives a very intuitive separation of handlers into two basic groups:

ICQ handlers

are handlers (also referred to as ``callbacks'') invoked by events in the ICQ network. In fact, they are being called by the icq_Main() function. Please refer to the icqlib manual for more information on callbacks.

The convention in the code is to name these handlers icq_handle_$x$ where $x$ is the event to be handled.

The callbacks implemented in the current version of csicq are:

• icq_handle_logged_in which handles connection establishment messages from the ICQ network, informing the client that they are connected to the network and initializing the contact list.

• icq_handle_not_logged_in which handles messages from the ICQ network notifying that we could not login to the network, notifying the user that the attempt was unsuccessful.

• icq_handle_disconnect which handles messages from the ICQ network notifying that we have been disconnected from the network, notifying the user of that and trying to reconnect.

• icq_handle_recv_message which handles the event of a new message received by the user. The handler composes a message to the user using our protocol and sends if over the TCP connection, notifying the user of the incoming message.

• icq_handle_update_status handles the event of a change in status of one of the user's contacts. The handler composes a message to the user using our protocol and sends if over the TCP connection, notifying the user of the change in status.

• icq_handle_user_online handles the event of a contact coming online. Similar to icq_handle_update_status.

• icq_handle_user_offline handles the event of a contact going offline. Similar to icq_handle_update_status.

• icq_handle_arv_ack handles the event of receiving server ack message. This handler is not used by the current version of csicq and used for testing purposes only.

User handlers

are invoked as a response to an event on the user connection. The user sends a message using our protocol, it is being received and then interpreted by the handle_message function (which is not really a handler but rather a dispatcher of messages to handlers). The function determines according to the message type which user handler should be invoked and activates it. The naming convention for these handlers is handle_$x$ where $x$ is the event to be handled.

The handlers implemented in the current version of csicq are:

• handle_login_req handles a login request fro mthe user. It initializes the ICQLINK of the connection and attempts to connect to the ICQ network.

• handle_disconnect handles a disconnection request from the user. Namely it ends the session.

• handle_send_msg handles a request by the user to send a message. The handler calls the appropriate icqlib function to forward the message to the ICQ network.

• handle_add_usr handles a user request to add some contact to their contact list. The handler adds the new contact to the list of contacts and notifies the ICQ network of the addition.

• handle_del_usr handles a user request to remove a contact from their contact list. The handler removes the contact from the contact list.