During a migration from one IMAP server to another, the need arose to run both the old and the new IMAP servers in paralell. By default,
Horde only allows a single primary server to be enabled in servers.php. Of course, we could have allowed our users to simply select
their server by enabling IMAP server selection, but there is a better way. What follows are instructions on using a MySQL backend to
select an IMAP server for authentication, given a username:
There are many ways to do this of course. In this example, we'll just be using a table with two rows:
| username | server.domain.com |
Your table can be constructed however you like. It can even be a part of your existing DB. The important point is that you need the
table to be constructed in such a way as to be able to query a username and have the lookup return a servername. Our example
uses a table called 'host'.
Here's some sample code for a hook that could be placed into horde/config/hooks.php:
if (!function_exists('_imp_hook_imap')) {
function _imp_hook_imap($userName)
{
global $conf;
include_once 'DB.php';
$_db = &DB::connect($conf['sql'], true);
$query = sprintf('SELECT server FROM host WHERE user=%s', $_db->quote($userName));
$result = $_db->getOne($query);
if (!is_a($result, 'PEAR_Error')) {
return $result;
} else {
return false;
}
}
}
The above hook returns a single line containing a server name. It's injected into /horde/imp/lib/Session.php as follows:
if (!empty($GLOBALS['conf']['hooks']['imap'])) {
require_once HORDE_BASE . '/config/hooks.php';
if (function_exists('_imp_hook_imap')) {
$_SESSION['imp']['server'] = call_user_func('_imp_hook_imap', $_SESSION['imp']['user']);
}
}
On our setup, this is done right before authentication is attempted (right around line 223). As best I can tell, you're fine so long
as you don't have $_SESSION['imp']['server'] overwritten by anything else before you get to the call to &Auth::singleton(array('imp', 'imp'));
This code works on our setup so far. It could be wrong, uneccesary, foolish, or otherwise idiotic. In short, YMMV.