<html>
<body>
<div style="font-family: Verdana, Arial, Helvetica, Sans-Serif;">
<table bgcolor="#f9f3c9" width="100%" cellpadding="8" style="border: 1px #c9c399 solid;">
<tr>
<td>
This is an automatically generated e-mail. To reply, visit:
<a href="https://reviewboard.asterisk.org/r/1977/">https://reviewboard.asterisk.org/r/1977/</a>
</td>
</tr>
</table>
<br />
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="8" style="background-image: url('https://reviewboard.asterisk.org/media/rb/images/review_request_box_top_bg.png'); background-position: left top; background-repeat: repeat-x; border: 1px black solid;">
<tr>
<td>
<div>Review request for Asterisk Developers.</div>
<div>By Mark Michelson.</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px solid #b8b5a0">
<tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">When Asterisk receives what it believes to be a dialog-starting INVITE with a to-tag, Asterisk will reply with a 481. There was an issue where Asterisk would not recognize the incoming ACK of the 481 because Asterisk's internally generated to-tag did not match the actual to-tag used in the transaction. My initial fix for this was to make Asterisk send its generated to-tag in the 481 to essentially "change" the to-tag of the transaction. This way, the UA would respond with an ACK with a matching to-tag and all would be happy.
Unfortunately, it was pointed out to me that just because Asterisk thinks that an INVITE is out-of-dialog doesn't make it so. For instance, Asterisk could crash with a SIP dialog up, be restarted, and then receive a reinvite for that dialog. The new Asterisk instance would have no knowledge of the dialog, so it would think the INVITE was out-of-dialog with an illegitimate to-tag. In this case, the sender of the reinvite would not recognize the 481 as being in-dialog and would thus continue retransmitting the reinvite until the transaction timed out.
The new approach here is to update Asterisk's local tag to be the to-tag present in the INVITE in the case that Asterisk will be transmitting a 481 response. Taking this approach meant having to change the local tag to be a string field instead of a static buffer and rewriting the make_our_tag() method.</pre>
</td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: 1px solid #b8b5a0">
<tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">I have tested using Walter Doekes's 481 test. The 481 that Asterisk sends has the same to-tag as the INVITE, and Asterisk properly recognizes the inbound ACK.</pre>
</td>
</tr>
</table>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>
<a href="https://issues.asterisk.org/jira/browse/ASTERISK-19892">ASTERISK-19892</a>
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>/branches/1.8/channels/chan_sip.c <span style="color: grey">(368625)</span></li>
<li>/branches/1.8/channels/sip/include/sip.h <span style="color: grey">(368624)</span></li>
</ul>
<p><a href="https://reviewboard.asterisk.org/r/1977/diff/" style="margin-left: 3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>