Hello Community,

We were facing a weird issue in one of our Kamailio servers where custom htable entries were removed which did not belong to a particular call.

Background Information:

We use htable to store the call-id and a uuid when an INVITE message is received and remove these entries when the call is completed/failed (so on CANCEL, BYE, 4XX, 5XX, 6XX, etc).

In this case the function sht_rm_name_re was causing incremented call-id’s belonging to different calls to be removed from the htable, since the removal is based on regex and not the exact key.

On INVITE we do this:

$var(reference) = $uuid(g);

$sht(calls=>$ci) = $ci;

$sht(calls=>$ci::reference) = $var(reference);

On BYE/4XX,5XX,6XX, etc we did this:

sht_rm_name_re("calls=>$ci");

sht_rm_name_re("calls=>$ci::reference");

SIPP generates incremented call-id’s, like this: 1-14875@1.0.0.1.

When you generate enough calls, for instance 30 calls, the 21^st call will have the call-id 21-14875@1.0.0.1.

If for instance the BYE for the call-id 1-14875@1.0.0.1 arrives before 21-14875@1.0.0.1 , both htable entries will be removed by the sht_rm_name_re function, since it matches based on regex.

To fix this we made sure the function matches on the exact keys by doing this:

$var(callid) = '^' + $ci + '$';

$var(callid_reference) = '^' + $ci + '::reference' + '$';

sht_rm_name_re("calls=>$var(callid)");

sht_rm_name_re("calls=>$var(callid_reference)");

Hope this may help someone in the future facing the same issue.

Regards,

Grant Bagdasarian