[imp] IMAP login code

[Stephen A. Cochran Lists]

In IMP-4.1.1 lib/IMAP/Client.php on line 561, the generic IMAP login  
is handled with the following code:

         case 'login':
             $tag = $this->_generateSid();
             $query = $tag . " LOGIN $username {" . strlen 
($password) . "}\r\n";
             fwrite($this->_stream, $query);
             $read = $this->_fgets();
             if (substr($read, 0, 1) == '+') {
                 fwrite($this->_stream, "$password\r\n");
                 $read = $this->_fgets();
             } else {
                 return PEAR::raiseError(_("Unexpected response from  
server to LOGIN command."), 'horde.error');
             }
             break;

But this is failing against our IMAP server because of the check for  
the '+' as the first character in the response, and I believe it's  
incorrect according to the RFC:

<http://www.ietf.org/rfc/rfc3501.txt>

6.2.3.  LOGIN Command

    Arguments:  user name
                password

    Responses:  no specific responses for this command

    Result:     OK - login completed, now in authenticated state
                NO - login failure: user name or password rejected
                BAD - command unknown or arguments invalid

       The LOGIN command identifies the client to the server and carries
       the plaintext password authenticating this user.

An example given in section 6.2.1 also clearly demonstrates no plus  
sign returned in response to the LOGIN command:

    Example:    C: a001 CAPABILITY
                S: * CAPABILITY IMAP4rev1 STARTTLS LOGINDISABLED
                S: a001 OK CAPABILITY completed
                C: a002 STARTTLS
                S: a002 OK Begin TLS negotiation now
                <TLS negotiation, further commands are under [TLS]  
layer>
                C: a003 CAPABILITY
                S: * CAPABILITY IMAP4rev1 AUTH=PLAIN
                S: a003 OK CAPABILITY completed
                C: a004 LOGIN joe password
                S: a004 OK LOGIN completed


Steve Cochran