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    <tt>Hi Mariana,<br>
      <br>
      According to RFC3261, the CANCEL processing (as cancelling the
      call) is not up to a proxy, but up to the end devices. So a proxy
      has to simply relay all received info (INVITE and CANCEL) - it
      cannot terminate the call by itself.<br>
      <br>
      So you have to relay both INVITE and CANCEL and let the end device
      to reject the call.<br>
      <br>
      Regarding Flavio's suggestion - that function (as name says)
      solves the problem only for the flags, but not for changes as
      headers or SDP, AVPS, etc.<br>
      <br>
      Regards,<br>
    </tt>
    <pre class="moz-signature" cols="72">Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
<a class="moz-txt-link-freetext" href="http://www.opensips-solutions.com">http://www.opensips-solutions.com</a></pre>
    <br>
    On 01/09/2013 02:31 PM, Mariana Arduini wrote:
    <blockquote
cite="mid:CABHUZgBdV4Y6JaZb7N4GezcTKPObtpp9Mc1h3MJwXHWu7ZCS6Q@mail.gmail.com"
      type="cite">
      <div dir="ltr">Hi All!
        <div><br>
        </div>
        <div>Thank you both for the hints and explanation.</div>
        <div><br>
        </div>
        <div style="">The retransmission of CANCEL messages would for
          sure be really helpful, but we&acute;d like to be able to handle
          cases where processing the INVITE takes too long. If
          introducing some huge delays in INVITE processing, OpenSIPS
          will relay it when the processing finally ends, but UAC had
          already canceled it, so UAS picks a dead call up.</div>
        <div style=""><br>
        </div>
        <div style="">Flavio&acute;s suggestion looks interesting. I&acute;m just
          wondering if t_flush_flags() would update all kind of changes
          in the SIP message. We perform lots of translations in headers
          and SDP and not applying any of them would totally mess
          everything up. Any idea of limitations?</div>
        <div style=""><br>
        </div>
        <div style="">I begin to think that including timeouts during
          INVITE processing with smaller values than the previous hop
          fr_inv would be less risky. I&acute;d like to hear your oppinions.</div>
        <div style=""><br>
        </div>
        <div style="">Thanks again for the help!</div>
        <div style=""><br>
        </div>
        <div style="">Regards,</div>
        <div style="">Mariana.</div>
        <div style=""><br>
        </div>
      </div>
      <div class="gmail_extra"><br>
        <br>
        <div class="gmail_quote">On Wed, Jan 9, 2013 at 9:54 AM,
          Bogdan-Andrei Iancu <span dir="ltr">&lt;<a
              moz-do-not-send="true" href="mailto:bogdan@opensips.org"
              target="_blank">bogdan@opensips.org</a>&gt;</span> wrote:<br>
          <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
            0.8ex; border-left: 1px solid rgb(204, 204, 204);
            padding-left: 1ex;">
            <div bgcolor="#ffffff" text="#000000"> <tt>Hi Mariana,<br>
                <br>
                If CANCEL hits opensips while the the INVITE is still
                under processing (in a different process), the INVITE
                transaction will not exist yet (it is created by
                t_relay), so the t_check_trans() will return false -&gt;
                script will exit without doing anything for the CANCEL -
                more or less the CANCEL will be dropped without being
                replied or fwded. This will force retransmission of
                Cancel -&gt; buying more time to finish the processing
                of the INVITE.<br>
                <br>
                Hope this helped.<br>
                <br>
                Regards,<br>
              </tt>
              <pre cols="72">Bogdan-Andrei Iancu
OpenSIPS Founder and Developer
<a moz-do-not-send="true" href="http://www.opensips-solutions.com" target="_blank">http://www.opensips-solutions.com</a></pre>
              <div>
                <div class="h5"> <br>
                  On 01/08/2013 10:49 PM, Mariana Arduini wrote: </div>
              </div>
              <blockquote type="cite">
                <div>
                  <div class="h5">
                    <div dir="ltr">Hello all,
                      <div><br>
                      </div>
                      <div>I hope somebody can give me a kind hint on
                        what to do here.<br>
                        <div><br>
                        </div>
                        <div>We have this piece of code for CANCEL
                          handling:</div>
                        <div><br>
                        </div>
                        <div>
                          <div> &nbsp; &nbsp; # CANCEL processing</div>
                          <div>&nbsp; &nbsp; if (is_method("CANCEL")) {</div>
                          <div>&nbsp; &nbsp; &nbsp; &nbsp; if (t_check_trans()) {</div>
                          <div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; t_relay();</div>
                          <div>&nbsp; &nbsp; &nbsp; &nbsp; }</div>
                          <div>&nbsp; &nbsp; &nbsp; &nbsp; exit;</div>
                          <div>&nbsp; &nbsp; }</div>
                          <div><br>
                          </div>
                          <div>What happens is sometimes we take too
                            long to process the INVITE due to some DB
                            issues, and the UAC sends us a CANCEL before
                            we relay the INVITE.&nbsp;</div>
                          <div><br>
                          </div>
                          <div>We don&acute;t use t_newtran() because of this
                            big warning in docs saying that "<span
                              style="text-align: justify; font-size:
                              12px; font-family: Helvetica,Arial;">the
                              changes on the request that are made after
                              this function call will not be saved into
                              transaction!!!</span>". We need to perform
                            a lot of changes in the requests and I
                            understand this wouldn&acute;t be possible after
                            calling t_newtran().</div>
                          <div><br>
                          </div>
                          <div>So our transaction is not created untill
                            we relay the INVITE, which means that any
                            CANCEL received before that will be dropped.</div>
                          <div><br>
                          </div>
                          <div>We also tried testing the CANCEL messages
                            we&acute;re receiving in these cases with
                            has_totag() and loose_route(), but they
                            won&acute;t pass as well.</div>
                          <div><br>
                          </div>
                          <div>Is there any way to verify a CANCEL
                            message in this scenario and relay it in
                            case is belongs to a valid transaction?</div>
                          <div><br>
                          </div>
                          <div>Any help will be much appreciated.</div>
                          <div><br>
                          </div>
                          <div>Regards,</div>
                          <div>Mariana.</div>
                        </div>
                      </div>
                    </div>
                  </div>
                </div>
                <pre><fieldset></fieldset>
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