[SR-Users] Htable sht_rm_name_re usage

[Grant Bagdasarian]

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 at 1.0.0.1<mailto:1-14875 at 1.0.0.1>.
When you generate enough calls, for instance 30 calls, the 21st call will have the call-id 21-14875 at 1.0.0.1<mailto:21-14875 at 1.0.0.1>.
If for instance the BYE for the call-id 1-14875 at 1.0.0.1<mailto:1-14875 at 1.0.0.1> arrives before 21-14875 at 1.0.0.1<mailto:21-14875 at 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
CM

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