[Serusers] [RFC] ideas about new dialog module

Hi, I am thinking about writing a new module for SER, which will track SIP dialogs and will serve as an abstraction layer for other modules, much like the tm module now. We need such module for 2 reasons: 1. Call accounting. Our billing engine is based on the assumption that a node provides accounting information for completed calls, not for individual transactions. It is easier for us to extend proxy with similar features than to modify billing engine to do transaction matching. 2. Debit card application. Currently, there is no way to use SER for debit card applications, where it is necessary to set the maximum duration of the call and terminate it forcefully if that duration is exceeded. The raw idea is as follows: - the module will register callbacks with tm.register_tmcb(), probably TMCB_REQUEST_IN and TMCB_REPLY_IN ones and will match INVITEs to BYEs keeping information about the state of ongoing sessions in the shared memory. - the module will provide interested modules with ability to register several callbacks, i.e. on dialog creation/teardown and yet another callback on dialog timeouts (more about that below). - the module will provide utility functions for forceful termination of any ongoing dialog. - when invoking dialog creation callback function, the module will give the function opportunity to install a timer on that dialog, so that if the dialog is still active after timer expires, then some action is performed. For example, in the debit card applications, in such case the accounting module can decide to forcefully terminate a dialog. What do you think? -Maxim