A reply is re-sent in case of retransmission if the transaction of the first subscribe sent out already a reply, otherwise no -- you can see in the c code you pasted the function to retransmit reply.

Anyhow, it is up to yiou if you want to do retransmission handling as per default config, you can skip that part of config for subscribe by enclosing it inside an if block like:

if(!is_method("SUBSCRIBE")) {
  ...
}

Cheers,
Daniel

On 11.10.17 10:43, Jack Wang wrote:

Yes, the SUBSCRIBE was sent continuously 2~3 times captured by wireshark,

I tested using Ekiga as the sip client on windows 7.

However, after I rebooted the pc and re-test  this,

it only send one SUBSCRIBE now no matter how I tried,

even I changed the codes back.

And as you said, "it means that the same SUBSCRIBE was already processed...",

but I think it should send 200 OK and the NOTIFY back in a normal situation if it is indeed processed,

rather than stopping there when it received a retransmitted SIP message.

I can not generate the situation now, but I'll keep watching for this. 

Thanks. :)

2017-10-11 15:52 GMT+08:00 Daniel-Constantin Mierla <miconda@gmail.com>:

Hello,

it means that the same SUBSCRIBE was aready processed and the current one is a retransmission. Can you look at sip network traffic (using ngrep, sngrep, ...) and see if there are two SUBSCRIBE requests received?

Cheers,
Daniel

On 05.10.17 11:34, Jack Wang wrote:

Hello everyone,

According to the routing flow set in kamailio.cfg

 # handle retransmissions

 if(t_precheck_trans()) {

             t_check_trans();

             exit;

 }

t_check_trans();

After I traced the flow it seems that SUBSCRIBE message failed on t_check_trans() and stopped there.

I add some logs to keep tracing this function and found that:

int t_check_trans(struct sip_msg* msg) { struct cell* t; int branch; int ret; /* already processing a T */ if(is_route_type(FAILURE_ROUTE) || is_route_type(BRANCH_ROUTE) || is_route_type(BRANCH_FAILURE_ROUTE) || is_route_type(TM_ONREPLY_ROUTE)) { return 1; } if (msg->first_line.type==SIP_REPLY) { branch = 0; ret = (t_check_msg( msg , &branch)==1) ? 1 : -1; tm_ctx_set_branch_index(branch); return ret; } else if (msg->REQ_METHOD==METHOD_CANCEL) { return w_t_lookup_cancel(msg, 0, 0); } else { switch(t_check_msg(msg, 0)){ case -2: /* possible e2e ack */ return 1; case 1: /* found */ t=get_t(); if (msg->REQ_METHOD==METHOD_ACK){ /* ack to neg. reply or ack to local trans. => process it and end the script */ /* FIXME: there's no way to distinguish here between acks to local trans. and neg. acks */ if (unlikely(has_tran_tmcbs(t, TMCB_ACK_NEG_IN))) run_trans_callbacks(TMCB_ACK_NEG_IN, t, msg, 0, msg->REQ_METHOD); t_release_transaction(t); } else { /* is a retransmission */ if (unlikely(has_tran_tmcbs(t, TMCB_REQ_RETR_IN))) run_trans_callbacks(TMCB_REQ_RETR_IN, t, msg, 0, msg->REQ_METHOD); t_retransmit_reply(t); } /* no need for UNREF(t); set_t(0) - the end-of-script t_unref callback will take care of them */ return 0; /* exit from the script */ <---------------------------- THE POINT !! } /* not found or error */ } return -1; }

If the line "return 0; /* exit from the script */" was changed to "return 1; /* exit from the script */" , it works ---- means that the configuration script can keep being proceeded now.

Any suggestions?

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-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - www.asipto.com
Kamailio World Conference - www.kamailioworld.com

-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - www.asipto.com
Kamailio World Conference - www.kamailioworld.com