ssh.pm recv() stuck on logout

[LabRat002a]

Our software sometimes sends a request-logout-user command whose name also matches the active session: "$client->send_and_recv_rpc('our-name');" But the send_and_recv_rpm call never returns in that case. In older NET::NETCONF versions it caused the script to exit with an error message about losing connection, which is the desired behavior. Looking at the code, I expect it would also get stuck if the session spontaneously died for other reasons, like idle timeout.

Looking in the NET::NETCONF code, I traced this problem to 2 causes. One already appears to be addressed in #31 "adding exception handling for reads and writes". The other though is that poll() never returns when the session dies in this case. Poll() is calling libssh2_poll(), which is a deprecated function. I tried changing it to use blocking reads instead, but those weren't returning from read() even for commands that did work with non-blocking reads before.

[hatramatra]

I noticed also, that recv() never ends if ]]>]]> string it not the last string. That typically happens if the closing session reply message looks like this:

<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" xmlns:junos="http://xml.juniper.net/junos/14.1X53/junos" message-id='2'>
<ok/>
</rpc-reply>
]]>]]>
<!-- session end at 2018-09-01 19:08:23 UTC -->

In which case the condition terminating the reading loop ...

} until($resp =~ s/]]>]]>$//);

... never matches and it loops infinitely as it will never read anything again. The fix which worked for me was to use the multiline match:

--- ssh.pm.orig	2018-08-31 20:54:53.535774074 +0200
+++ ssh.pm	2018-09-01 22:33:46.234021174 +0200
@@ -126,7 +126,7 @@
         $nbytes = $chan->read($buf, 65536) || 0;
         $self->trace("Read $nbytes bytes from SSH channel: '$buf'");
         $resp .= $buf;
-    } until($resp =~ s/]]>]]>$//);
+    } until($resp =~ s/]]>]]>$//m);
     $self->trace("Received XML response '$resp'");
 
     return $resp;

Is this the right fix?