The following issue has been SUBMITTED. ====================================================================== http://www.dbmail.org/mantis/view.php?id=483 ====================================================================== Reported By: stsch Assigned To: ====================================================================== Project: DBMail Issue ID: 483 Category: POP3 daemon Reproducibility: always Severity: major Priority: normal Status: new target: ====================================================================== Date Submitted: 04-Jan-07 01:06 CET Last Modified: 04-Jan-07 01:06 CET ====================================================================== Summary: Possible race condition when using dbmail-pop3d, which results in receiving messages twice Description: When using dbmail-pop3d you can run into a race condition which results in receiving the same messages twice.
So, when a mail client sends the "QUIT" command at the end of a pop3 session, dbmail-pop3d responds immediately with "+OK ...". After sending that status the client disconnects and dbmail-pop3d is going on to do the usual cleanup work which includes a call to the function db_update_pop(..). The function "db_update_pop" is responsible for executing an "update" query for every deleted messages. Calling db_update_pop(...) _after_ the client disconnects ( which is possible because of the "+OK .." after the "QUIT" command ) , you can end up in a situation where one dbmail-pop3d process is busy updating the dbmail_messages table while another dbmail-pop3d process ( new pop3 session from the same client ! ) delivers the same mails to your client twice ( the mails you received and deleted in the first pop3 session ) You can trigger this with a filled mailbox ( http://www.dbmail.org/mantis/view.php?id=173#1000 messages ) and a mail client which starts immediately another pop3 session _after_ finishing the first one. So as long as the several hundred "update" queries are slower than the "select" queries for the login of the second pop3 session ( right after finishing the first one ) , you'll receive messages twice - race condition. ====================================================================== Issue History Date Modified Username Field Change ====================================================================== 04-Jan-07 01:06 stsch New Issue 04-Jan-07 01:06 stsch File Added: pop3_c.patch ====================================================================== _______________________________________________ Dbmail-dev mailing list Dbmail-dev@dbmail.org http://twister.fastxs.net/mailman/listinfo/dbmail-dev
