[Devel] ask invite/cancel race condition issue again

[Norman Brandinger]

Here is an example adapted from one of Klaus' postings.  Thanks Klaus.

#------------------------------------------------------------------
# CANCEL without matching INVITE transaction, discard it
#------------------------------------------------------------------
if ( is_method("CANCEL") && !t_check_trans() ) {
    # CANCEL without matching INVITE transaction, ignore
    # may happen if the INVITE is slower than the CANCEL
    #  ignore the CANCEL, as the client will retransmit it,
    # and maybe next time the INVITE transaction is already created
    xlog("L_NOTICE", "CANCEL without matching transaction discard.\n");
    exit;
}

Regards,
Norm


Bogdan-Andrei Iancu wrote:
> Hi Di-Shi,
>
> yes, there is a solution for this - at the beginning of the script use 
> t_check_tran() to see if the CANCEL does match an INVITE request. IF 
> no, just silently discard it - this will force the UAC to retransmit 
> the CANCEL until the proxy actually finished processing the INVITE 
> (and build transaction for it).
>
> BTW, fo you have any input for bug 1592883 ?
>
> regards,
> bogdan
>
> Di-Shi Sun wrote:
>> Hi All,
>>  
>> I met the INVITE/CANCEL race condition that had been disscussed long 
>> ago in this maillist. The formal script of this issue like this:
>>  
>> *the CANCEL arrives BEFORE the INVITE, or
>> *it arrives after but you are doing other high-cost processing steps 
>> (i.e., DNS lookup (ENUM)) before calling t_relay which will lead to 
>> process the CANCEL before creating the transaction.
>>  
>> It said that this issue had been fixed. But I cannot find the 
>> solution. Could anyone give me some suggestion?
>>  
>> Thanks,
>>  
>> Di-Shi Sun.
>>  
>> ------------------------------------------------------------------------
>>
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