[Tickets #3404] NEW: Rare random Logouts due loss of IMAP connection

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Ticket URL: http://bugs.horde.org/ticket/?id=3404
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 Ticket             | 3404
 Created By         | ag at netside.de
 Summary            | Rare random Logouts due loss of IMAP connection
 Queue              | IMP
 Version            | 4.0.1
 State              | New
 Priority           | 1. Low
 Type               | Enhancement
 Owners             | 
+New Attachment     | IMAP.php.changes.txt
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ag at netside.de (2006-02-03 10:06) wrote:

I'm right now monitoring a strange problem on a internal horde/imp setup
serving about 70 user. Authentication is IMAP-only and imp is the
login-app.

These users normally log on to their emails in the morning and keep that
window up and running until they leave work in the evening. They all have
set up a mailreminder to be instantly informed about new mail - so they
never get a session-timeout. 

Strangely sometimes one or more get logged of from horde while others stay
logged on at that point of time. This logoff occures on any action that
results in refreshing the webpage. And theres no timeout - klick and you're
back at login-page. Users who are writing a new mail loose their work if the
background-window with its refreshing INBOX gets logged of, because the
compose-popup is closed, too. This is really nasty!
You can't define a certain time-spot, any coincident or a method to cause
the users to get logged out.

I traced this thing down in a time consuming honeypot-method (as i named it)
placing a mail-sender at a prominent place to provide me with information of
imps state when someone gets logged off. By letting the honeypot move
backwards from the place the horde-log message "LOGIN FAILURE" i slowly
traced back to the origin of imps logout-reason. Everytime i made a change i
had to wait from several minutes to several hours for someone getting logged
off unreasonable.
I found the logout-reason in imp/lib/IMAP.php in the function
'openIMAPStream' which returned 'false' on every case of logged-off-users.
So i looked at imap_errors() and found constantly the same msg:
"Connection failed to 127.0.0.1,143: Die Wartezeit für die Verbindung ist
abgelaufen"
The german part of this message means something like "connection timeout" -
i don't know why this message is partly german.

Since horde/imp and the IMAP-server reside on the same machine i don't see a
reason for timeout, but i thought imp might need to retry to 'imap_open' the
IMAP stream a little more often.
I changed a part of the code in IMAP.php as you can see in the attached
file, where i documented the before- and after-state. Unless the last
imap_error is not something like 'login failure' my routine gives imap_open
10 chances to return a stream-result with a timeout of 0.3 sec between each
try. That would result at worst case in a >3 sec. delay before a user
finally gets thrown out of horde/imp.
My statistics on these rare cases show, that most imap_open that fail on
first try do succeed within 1 retry. The worst case so far had to do 2
retries.

I do think this is not a problem of imp! The imap server seems to be the
"bad boy" in this scenario, but this "feature" might be a nice improvement
to imp.

How about?

Regards Andreas