Monday, October 6, 2008

Registrar Enhancements

In the last time several enhancements were added to registrar module to help in dealing with user location records. This correlated with the new modue pv shall give lot of control over the destination set for calls.

To get the latest Kamailio (OpenSER) devel version, check out the latest svn:

svn co kamailio

The news in registrar module are:

- ability to unregister all contacts for a SIP addres - there is a new function: unregister(table, uri)
- ability to store and maintain single contact per user - the save() function accepts a new value for flags parameter (0x04) to restrict to one single record in location table
- ability to access the attributes of all contacts for a user - there are two new functions: reg_fetch_contacts(table, uri, profile) and reg_free_contacts(profile) to make available/release the contacts for a SIP uri. After fetching the contacts, the attributes can be accessed via pseudo variable $ulc(profile=>attr).

For more details see the README:

Here are couple of use cases:

1) only one contact per user

save("location", "0x04");

Note that if you have couple of phones registering for same user, the one that sent last REGISTER message will be the only ringing.

2) check if a user is calling from a registered device and if not, deny the call

if(!reg_fetch_contacts("location", "$fu", "caller"))
sl_send_reply("403", "Please register first");
$var(i) = 0;
$var(found) = 0;
$var(contact) = $(ct{nameaddr.uri});
while($var(found) == 0 && $var(i) < $(ulc(caller=>count)))
$var(found) = 1;
$var(i) = $var(i) + 1;
if($var(found) == 0)
sl_send_reply("403", "Please register first");

For the future:
- unregister() to get a $ulc(...) variable as parameter to unregister a specific contact
- drop a branch via pv module

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