[dev] IMAP path prefix not set in horde webmail 5.2

[Quinn Comendant]

Hello horde-dev,

I have had difficulty setting the IMAP path prefix in horde webmail 5.2 on a CentOS 6 server running Courier-IMAP 4.1.2. When creating folders I was getting the error, "The mailbox 'New folder' was not created. This is what the server said: IMAP error reported by server."

The imp_imap debug log shows that it is trying to create folders  
without the `INBOX.` prefix, which I think is the reason it is failing:

	S: * OK [CAPABILITY IMAP4rev1] Courier-IMAP ready. Copyright 1998-2005  
	Double Precision, Inc.  See COPYING for distribution information.
	C: 1 LOGIN quinn at example.com [PASSWORD]
	S: 1 OK LOGIN Ok.
	C: 2 LSUB "" New folder
	S: 2 OK LSUB completed
	C: 3 LIST "" New folder
	S: 3 OK LIST completed
	C: 4 CREATE New folder
	S: 4 NO Invalid mailbox name.
	C: 5 LOGOUT
	S: * BYE Courier-IMAP server shutting down
	S: 5 OK LOGOUT completed

I *am* able to create a folder if I manually include the IMAP prefix  
to its name, i.e. I go to Folder Actions > Create Mailbox and then use  
a folder name literally as `INBOX.New folder`. The new folder is created  
with that name literally and `INBOX.New folder` is created on the server and  
is displayed in IMP's sidebar. =\

As far as I can tell, this is configured using the 'namespace' option  
in backends.local.php, but I have tried the following variations with  
no success:

     'namespace' => array('INBOX.')
     'namespace' => array('#INBOX.')
     'namespace' => array('INBOX/')
     'namespace' => array('#INBOX/')

I believe the correct method of setting the IMAP path prefix is to define the following in backends.local.php:

    'namespace' => array('INBOX.'),

However, that alone has not solved the problem. I may have found issues with horde/imp or our server configuration. Now, even with the namespace specified thusly, IMP is still sending IMAP commands without the namespace (i.e., `CREATE New folder` instead of `CREATE INBOX.New folder`).

I have read the source code of horde/imp and found the following changes were required for this to work:

## /var/www/html/horde/imp/lib/Imap.php : 474

The `getNamespace()` function defined here would return null when the specified mailbox was the default, despite `$this->getNamespaces()` returning a valid result. To solve this I added the following at line 474:

    if ($mailbox === self::NS_DEFAULT && $ns->count() == 1) {
        return end(end($ns));
    }

## /usr/share/pear/Horde/Imap/Client/Base.php : 742

Here, the name of the namespace is an array and would result in an array-to-string conversion, with the resulting namespace name `Array` instead of the correct name `INBOX`. I've added a tertiary clause to test if it is an array before assigning the value. Secondly, the namespace name lacking the delimiter would result in the use of folder names such as `INBOXNew folder` instead of `INBOX.New folder` (because in other parts of the code where the namespace is used the namespace is concatenated with the folder name with no delimiter), so I added the delimiter to the name here. The following is a modification of line 742:

    $ob->name = (is_array($val) ? end($val) : $val) . $val['delimiter'];

With these two changes, horde/imp is now successfully creating folders, displaying folders, auto-creating special folders, and moving messages between folders. The IMAP transactions now send the prefix correctly:

	S: * OK [CAPABILITY IMAP4rev1] Courier-IMAP ready. Copyright 1998-2005 Double Precision, Inc.  See COPYING for distribution information.
	C: 1 LOGIN q at asdf.com [PASSWORD]
	S: 1 OK LOGIN Ok.
	C: 2 LIST "" INBOX.
	S: * LIST (\Marked \HasChildren) "." "INBOX"
	S: 2 OK LIST completed
	C: 3 LSUB "" "INBOX.New folder"
	S: 3 OK LSUB completed
	C: 4 LIST "" "INBOX.New folder"
	S: 4 OK LIST completed
	C: 5 CREATE "INBOX.New folder"
	S: 5 OK "INBOX.New folder" created.
	C: 6 LSUB "" "INBOX.New folder"
	S: 6 OK LSUB completed
	C: 7 LIST "" "INBOX.New folder"
	S: * LIST (\HasNoChildren) "." "INBOX.New folder"
	S: 7 OK LIST completed
	C: 8 LOGOUT
	S: * BYE Courier-IMAP server shutting down
	S: 8 OK LOGOUT completed

If I have discovered bugs in horde/imp 5.2, please let me know how best I can contribute these changes (pull request on github?) or if you believe this is a problem with my Courier IMAP configuration, I would appreciate some help identifying if that may be the case.

Attached is IMP's imap log output during a successful folder creation operation (also so you can see imap capabilities, etc).

Regards,

Quinn