Hello,

t_precheck_trans() is returning true if a SIP worker process has received the SIP request and it is handling it at that moment. However, in case of a retransmission, that can be at the moment when the transaction was already created for the previous same requests (e.g., via t_newtran() or the execution is in a branch_route block). The specs require that a stateful proxy re-sends the last response in case of a re-transmission. t_check_trans() is used for that purpose, to see if the transaction was already created and to what specs require.

If still not clear, I will try to add more details.

Cheers,
Daniel

Probably an elementary question, but we're relatively new at digging into the details.  We are trying to understand the following block of config code and have a question or two.  Our assumption is the t_precheck_trans() function tells us whether another packet has arrived already as a retransmission.  However, we're not clear on what the t_check_trans() is doing assuming the condition is true.  Any direction on this?

Thanks.

route[CHECK_RETRANS]

{

  # handle retransmissions

    if(t_precheck_trans()) {

        t_check_trans();

        exit;

    }

}

Joe Baran

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