# &adminguide;

## Overview

This module was designed to act as a mechanism to limit call duration based on credit information parameters. After getting the credit information of the call being set up, you can instruct the module to start monitoring the consumed credit to shutdown a single call or a group of calls in case of credit exhaustion.

Every call is associated to an unique client/customer identifier. If a credit event occurs, all calls hooked to this identifier are automatically shutdown.

Cnxcc is dialog-aware so there's no need to explicitly allocate/deallocate the monitoring. The dlg_manage() function must be called in the configuration file for the dialog to be tracked.

The credit discount rate is proportional to the number of calls grouped inside an identifier. Once the setup of the first call is done, the information remains while the call is active. If the customer starts a new call with the same routing criteria, it will land in the same monitoring bag and it will consume the same pool of credit in rates that are equal to the cost per second of both calls.

If your accounting program does not maintain the state of the call in real time, this module can provide you with that ability.

Cnxcc can also provide more common means of monitoring, i.e., by time limit or by maximum simultaneous calls.

## Dependencies

### Modules

The following module must be loaded before this module:

- dialog

### Libraries

The following module must be loaded before this module:

- hiredis-devel >= 0.11.0

- libevent-devel >= 2.0.18-2

## Parameters

### `redis` (integer)

Redis datasource connection information

#### redis parameter

    ...
    modparam("cnxcc", "redis", "addr=127.0.0.1;port=6379;db=1")
    ...

### `credit_check_period` (integer)

Indicates how often the credit checking function should be called. It is directly related to the precision of the module. The maximum precision is 1, which means that every call is checked every one second.

Values greater than 1 leads to precision lost but less CPU consumption.

#### credit_check_period parameter

    ...
    modparam("cnxcc", "credit_check_period", 1)
    ...

## Functions

### `cnxcc_set_max_credit(customer, maxcredit, connect, cps, ipulse, fpulse)`

The dlg_manage() function must be called in the configuration file to ensure dialog is tracked.

Associates the call with a customer id and sets the max credit, connect cost, cost per second, initial pulse and final pulse. The discount is calculated in pulses (1/1, 60/1, etc) and subtracted from the pool of credit.

The customer value can be provided as a string or a variable holding a string. This value identifies all calls from the same customer.

The maxcredit (float) value is the maximum credit available for the current call.

The connect (float) value is the connect cost for the current call.

The cps (float) value is the cost per second for the current call.

The ipuse (integer) value is the initial pulse and establishes the minimum time to be charged. For example, value 1 establishes a charge per second and value 60 sets a charge per minute. If it is taken as value 60, even if the duration is 5 seconds, 1 minute will be charged.

The fpulse (integer) value is the final pulse and establishes, from the initial pulse, the time range to be charged. For example, the value 1 establishes a charge per second, 5 sets a charge in blocks of 5 seconds, 60 sets a full minute charge.

1/1 will make a charge per seconds for the entire call. 60/1 will make a charge per seconds with the first full minute. 60/60 always perform a full minute charge.

Return code:

- 1 - successful

- -1 - failed, error logged

- -4 - call-id already present for this client

#### cnxcc_set_max_credit()

    ...
    cnxcc_set_max_credit("john-doe", "100", "3.0", "0.5", 60, 1);
    ...
    $var(customer)  = "john-doe"; # customer id
    $var(credit)    = "100";      # max credit for all calls with the same
                                  # customer id
    $var(connect)   = "3.0";      # connect cost or initial cost for the call
    $var(cps)       = "0.5";      # cost per second
    $var(initial_p) = 60;         # initial pulse (60 = the first minute will be
                                  # charged even if the call is shorter)
    $var(final_p)   = 1;          # final pulse (after the first minute, it will
                                  # be charge in ranges of 1 second)
    cnxcc_set_max_credit("$var(customer)", "$var(credit)", "$var(connect)",
            "$var(cps)", "$var(initial_p)", "$var(final_p)");
    ...

### `cnxcc_set_max_time(customer, maxtime)`

The dlg_manage() function must be called in the configuration file to ensure dialog is tracked.

Specifies the amount of time the call should last at most.

The customer value can be provided as a string or a variable holding a string.

The maxtime value is an integer values, it can be also given via a variable holding an integer.

Return code:

- 1 - successful

- -1 - failed, error logged

- -4 - call-id already present for this client

#### cnxcc_set_max_time()

    ...
    $var(customer) = "john-doe-basic";
    $var(max_time) = 120;
    cnxcc_set_max_time("$var(customer)", "$var(max_time)");
    ...

### `cnxcc_update_max_time(customer, maxtime)`

The dlg_manage() function must be called in the configuration file to ensure dialog is tracked.

Updates max-time of an established and monitored call. This can be used to grant minimum values and to update them every short periods on time as a mean to prevent frauds and/or to mimic requested/granted units of time of Credit Control Application behavior.

The customer value can be provided as a string or a variable holding a string.

The maxtime value is an integer values, it can be also given via a variable holding an integer.

Return code:

- 1 - successful

- -1 - failed, error logged

#### cnxcc_update_max_time()

    ...
    $var(client)       = "john-doe-basic";
    $var(update_time)  = 5;

    if (!cnxcc_update_max_time("$var(client)", "$var(update_time)")) {
    	xlog("Error updating max-time");
    	return;
    	}
    ...

### `cnxcc_set_max_channel(customer, maxchan)`

The dlg_manage() function must be called in the configuration file to ensure dialog is tracked.

Specifies a limit for the number of simultaneous calls.

The customer value can be provided as a string or a variable holding a string.

The maxchan value is an integer values, it can be also given via a variable holding an integer.

Return code:

- 1 - successful

- -1 - failed, error logged

- -2 - failed, calls established plus calls being established result in more than the limit you specified

- -3 - failed, number of calls established is more than the limit you specified

- -4 - call-id already present for this client

#### cnxcc_set_max_channels()

    ...
    $var(customer)  = "john-doe-123-basic";
    $var(max_chan)  = 2;
    $var(retcode)   = cnxcc_set_max_channels("$var(customer)", "$var(max_chan)");

    if ($var(retcode) == -1) {
    	xlog("Error setting up credit control");
    	return;
    }

    if ($var(retcode) < -1) {
    	xlog("Too many channels for customer");
    	sl_send_reply(403, "Forbidden");

    	if (!cnxcc_terminate_all("$var(customer)")) {
    		xlog("Error terminating customer's calls");
    	}

    	exit;
    }
    ...

### `cnxcc_terminate_all(customer)`

Terminates all calls of the specified customer/profile.

The customer value can be provided as a string or a variable holding a string.

Return code:

- 1 - successful

- -1 - failed, error logged

#### cnxcc_set_max_time()

    ...
    $var(customer)  = "john-doe-123-basic";

    if (!cnxcc_terminate_all("$var(customer)")) {
    	xlog("Error terminating customer's calls");
    }
    ...

## RPC Commands

### cnxcc.active_clients

Retrieves all calls grouped by their identifiers.

Parameters: none

Example:

    ...
    &sercmd; cnxcc.active_clients
    ...

### cnxcc.check_client

Retrieves all calls from a particular identifier.

Parameters: client/customer identifier

Example:

    ...
    &sercmd; cnxcc.check_client john-doe-premium
    ...

### cnxcc.kill_call

Kills an active call using its call ID.

Parameters: Call-ID

Example:

    ....
    &sercmd; cnxcc.kill_call test@carlosrdcnx-laptop.site
    ...

### cnxcc.stats

List credit control stats.

Parameters: none

Example:

    ...
    &sercmd; cnxcc.stats
    ...

## Events

When a call is forced to end an event route is automatically invoked. This route is suited with a fake OPTIONS message containing the call ID, ftag and ttag of the original call so it can be located somehow in the accounting database.

Example:

    ...
    event_route[cnxcc:call-shutdown]
    {
    	xlog("L_INFO", "[$ci]: call killed");

    	# perform some kind of notification, database update, email sending, etc.
    }
    ...

## Web Interface

The module contains a web management interface completely optional. With it, you can review your calls in real time and hang them up if necessary.

Link: https://github.com/caruizdiaz/cnxcc-web

## Sample Config

### kamailio-cnxcc.cfg

    ...
    route[CNXCC]
    {
    	$var(client)              = "test-client";
    	$var(credit)              = "50";
    	$var(connect_cost)        = "3.0";
    	$var(cost_per_sec)        = "0.5";
    	$var(i_pulse)             = 30;
    	$var(f_pulse)             = 6;

    	cnxcc_set_max_credit("$var(client)",
    			"$var(credit)",
    			"$var(connect_cost)",
    			"$var(cost_per_sec)",
    			"$var(i_pulse)",
    			"$var(f_pulse)");

    	switch ($?) {
    		case -1:
    			xerr("Error setting up credit control");
    			sl_send_reply("503", "Internal Server Error");
    		case -4:
    			xwarn("$ci already present for client $var(client)");
    	};
    }

    event_route[cnxcc:call-shutdown]
    {
    	xlog("L_INFO", "[$ci]: call killed");
    }
    ...