1.2.1. OpenSER Modules

The following modules must be loaded before this module:

• No dependencies on other OpenSER modules.

1.2.2. External Libraries or Applications

The following libraries or applications must be installed before running OpenSER with this module loaded:

• None.

1.3.1. max_limit (integer)

Set an upper limit for the max-forward value in the outgoing requests. If the header is present, the decremented value is not allowed to exceed this max_limits - if it does, the header value will by decreased to "max_limit".

Note: This check is done when calling the mf_process_maxfwd_header() header.

The range of values stretches from 1 to 256, which is the maximum MAX-FORWARDS value allowed by RFC 3261.

Default value is "256".

...
modparam("maxfwd", "max_limit", 32)
...

1.4.1. mf_process_maxfwd_header(max_value)

If no Max-Forward header is present in the received request, a header will be added having the original value equal with "max_value". If a Max-Forward header is already present, its value will be decremented (if not 0).

Retuning codes:

• 2 (true) - header was not found and a new header was succesfully added.

• 1 (true) - header was found and its value was successfully decremented (had a non-0 value).

• -1 (false) - the header was found and its value is 0 (cannot be decremented).

• -2 (false) - error during processing.

The return code may be extensivly tested via script variable "retcode" (or "$?").

Meaning of the parameters is as follows:

• max_value - Value to be added if there is no Max-Forwards header field in the message.

This function can be used from REQUEST_ROUTE.

...
# initial sanity checks -- messages with
# max_forwards==0, or excessively long requests
if (!mf_process_maxfwd_header("10") && retcode==-1) {
	sl_send_reply("483","Too Many Hops");
	exit;
};
...

1.4.2. is_maxfwd_lt(max_value)

Checks if the Max-Forward header value is less then the "max_value" parameter value. It considers also the value of the new inserted header (if locally added).

Retuning codes:

• 1 (true) - header was found or set and its value is stricly less than "max_value".

• -1 (false) - the header was found or set and its value is greater or equal to "max_value".

• -2 (false) - header was not found or not set.

• -3 (false) - error during processing.

The return code may be extensivly tested via script variable "retcode" (or "$?").

Meaning of the parameters is as follows:

• max_value - value to check the Max-Forward.value against (as less than).

...
# next hope is a gateway, so make no sens to
# forward if MF is 0 (after decrement)
if ( is_maxfwd_lt("1") ) {
	sl_send_reply("483","Too Many Hops");
	exit;
};
...