How can i use my existing cakephp based project users to work with XMPP ejabberd chat application - xmpp

Question

I have a cakephp2.3 based project with table name "user_master".
I am using ejabberd chat application and ejabberd user table name is "user".
I am using convers.js client.
Now i am facing problem to use my existing project user with XMPP ejabberd to authenticate , send friend request , chat with friends.
I tried using external auth but it allowed me to login even if I add wrong credentials on ejabberd server using http://localhost:5280/admin link.
I am using Ubuntu and i have add all types of setting.It is working fine if i use it as stand alone application but when i want use it for my existing user it stopped working.
Ejabberd Server : http://localhost:5280/admin
External authentication configuration in "ejabberd.cfg" file.
{auth_method, external}.
{extauth_program, "/etc/ejabberd/auth.php"}.
External authentication file "auth.php".
<?php
require 'ejabberd_external_auth.php';
class Auth extends EjabberdExternalAuth {
protected function authenticate($user, $server, $password) {
$stmt = $this->db()->prepare("SELECT username FROM users WHERE username = ? AND password = ? ");
$stmt->execute(array($user, $password));
if($stmt->rowCount() >= 0 )
{
return true;
}
else
{
return false;
}
}
protected function exists($user, $server) {
$stmt = $this->db()->prepare("SELECT username FROM users WHERE username = ? ");
$stmt->execute(array($user));
if($stmt->rowCount() >= 0 )
{
return true;
}
else
{
return false;
}
}
}
$pdo = new PDO('mysql:dbname=ejabberd;host=localhost', 'root', 'root');
new Auth($pdo, 'auth.log');
Thanks in advance