[Freeswitch-users] Limit application usage in Lua

[Florent Krieg]

Hi Michael,

Actually, here is what happens:

Context: XML dialplan with the following extensions:
        <extension name="limit_exceeded">
            <condition field="destination_number"
expression="^limit_exceeded$">
                <action application="respond" data="503"/>
            </condition>
        </extension>
        <extension name="outgoing_call">
            <condition>
                <action application="lua"
data="dialplans/caller_script.lua"/>
            </condition>
        </extension>

1/ a call is started, the second extension entry in the XML dialplan
matches and the action starts the lua script
2/ after having set some (a lot actually) variables, here is the code part
for checking call-rate limits:
-- Security (to avoid outage): limit CAPS
--   hash backend is needed when using interval
--   2 call attempts per 10 seconds here
logz("[Calls limit] Checking caps for " .. billedcaller)
session:execute("limit", "hash " .. billedcaller .. " caps 2/10
!REQUESTED_CHAN_UNAVAIL")
rate_var = session:getVariable("limit_rate_" .. billedcaller .. "_caps")
if not rate_var then
    logz("[Calls limit] CAPS limit reached for " .. billedcaller .. ",
aborting the dialplan.")
    return
end
3/ after this code part, a lot of processing is done (for instance checking
call restrictions calling external web services and so on), it's like 600
lines of lua there
4/ in the end, the session:execute bridge app is run

At 2/, when limit is exceeded, I see in the log:
2015-03-13 12:22:40.454660 [INFO] switch_cpp.cpp:1328 * (caller/0) #
7a16c525263a8bb740517f5a28552016 at trunkinge.voip * [Calls limit] Checking
caps for asteriskrd at trunkinge.voip
EXECUTE sofia/internal_auth/asteriskrd at trunkinge.voip limit(hash
asteriskrd at trunkinge.voip caps 2/10 !REQUESTED_CHAN_UNAVAIL)
2015-03-13 12:22:40.454660 [DEBUG] switch_limit.c:126 incr called:
asteriskrd at trunkinge.voip_caps max:2, interval:10
2015-03-13 12:22:40.454660 [INFO] mod_hash.c:176 Usage for
asteriskrd at trunkinge.voip_caps exceeds maximum rate of 2/10s, now at 3
2015-03-13 12:22:40.454660 [INFO] switch_cpp.cpp:1328 * (caller/0) #
7a16c525263a8bb740517f5a28552016 at trunkinge.voip * [Calls limit] CAPS limit
reached for asteriskrd at trunkinge.voip, aborting the dialplan.

and the a-leg is successfully hangup.

But here, 3/ and 4/ are aborting only because of that code part:
rate_var = session:getVariable("limit_rate_" .. billedcaller .. "_caps")
if not rate_var then
    logz("[Calls limit] CAPS limit reached for " .. billedcaller .. ",
aborting the dialplan.")
    return
end

It works, but I'm pretty sure that it is not the proper way to do it.

If I remove that code part, even though the a-leg is hangup because of the
leg being transferred to 'limit_exceeded', the rest of the dialplan is
still processed, even though the call is aborted.

I'd like to be able to catch right after doing session:execute limit app,
the return of the command.
If the call is transferred to 'limit_exceeded', then I'd like to abort the
rest of the dialplan execution.

I have to admit I might be missing something here therefore if you can help
me, that'd be amazing.
Thanks in advance
Florent


2015-03-12 21:28 GMT+01:00 Michael S Collins <msc at freeswitch.org>:

> Some context here would be helpful. Can you pastebin your Lua script, or
> at least the relevant lines that demonstrate what is happening? Also, when
> you say that the rest of the Lua dialplan is still processed, what does
> that mean?
>
>
>
> -MC
>
>
>
> *From:* freeswitch-users-bounces at lists.freeswitch.org [mailto:
> freeswitch-users-bounces at lists.freeswitch.org] *On Behalf Of *Florent
> Krieg
> *Sent:* Thursday, March 12, 2015 11:43 AM
> *To:* FreeSWITCH Users Help
> *Subject:* [Freeswitch-users] Limit application usage in Lua
>
>
>
> Hi all,
>
> I wanted to implement call rate limits using this Lua instruction:
> session:execute("limit", "hash " .. billedcaller .. " caps 10/1
> !REQUESTED_CHAN_UNAVAIL")
>
> It is actually working, but the rest of the Lua dialplan is still
> processed, which is a problem in my case.
>
> I made a dirty but quick workaround, looking like this:
> rate_var = session:getVariable("limit_rate_" .. billedcaller .. "_caps")
> if not rate_var then
>     logz("[Calls limit] CAPS limit reached for " .. billedcaller .. ",
> aborting the dialplan.")
>     return
> end
>
> How can it be done properly?
>
> Is there a way to be able to get the result of the 'limit' app call?
>
> Or shall I check the status of the a-leg just after to decide to process
> the rest of the dialplan or not?
>
> I know that this issue doesn't occur in a 'pure' XML dialplan, but I'm
> trying to find a solution for my Lua-only dialplan.
>
> Thanks in advance if you have any idea.
>
> I'm willing to try any possible solution you would think about!
>
> Florent
>
>
>
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