LDAP authentication.

ldap.php

$conn = ldap_connect($host, $port);
if ($conn) {
    echo "ldap connected\n";
    if (ldap_bind($conn, $bind_dn, $password)) {
        echo "bind suceeded\n";
        $search_result = ldap_search($conn, $base_dn, "(&(objectClass=person)(uid={$username}))");
        if ($search_result) {
            echo "search suceeded\n";
            $entries = ldap_get_entries($conn, $search_result);
            if (0 < count($entries)) {
                $user_dn = $entries[0]['dn'];
                if (ldap_bind($conn, $user_dn, $userpwd)) {
                    echo "user authentication succeeded\n";
                } else {
                    echo "user authentication failed\n";
                }
            } 
        }
    } else {
        echo "bind failed\n";
    }
    ldap_close($conn);
} else {
    echo "connect faild\n";
}