Description:
------------
I made a script that get the mac address of users on my LAN, and then check in an openldap directory if it exists or not.
The probleme is that it seems to be impossible to pass a dynamic variable to "ldap_search()" for the "filter" field.

Reproduce code:
---------------
<?php
function get_mac(){
        $user_ip = $_SERVER['REMOTE_ADDR'];
        $user_mac = shell_exec('/usr/sbin/arp -a '.$user_ip.' | cut -d" " -f4');
        return $user_mac;
}
$mac = get_mac();               //the client's MAC (on my LAN) is now stored in $mac
$ldap_host = "127.0.0.1";       //my LDAP server
$connect = ldap_connect($ldap_host);                    //get a resource identifier
$base_dn = "ou=utilisateurs,dc=pinel-wifi,dc=org";      //where to search in the directory
$filter = "pager=$mac";
echo $filter;                   //to see if $filter is really what it should be
echo "<br>";
$sr=ldap_search($connect, $base_dn, $filter);           //let's search!
?>


Expected result:
----------------
the value of $filter should be placed correctly in the ldap_search function. In my ldap log, I should have :
May  6 01:47:13 Pinel-WiFi slapd[341]: conn=56 fd=14 ACCEPT from IP=127.0.0.1:32866 (IP=0.0.0.0:389)
May  6 01:47:13 Pinel-WiFi slapd[526]: begin get_filter
May  6 01:47:13 Pinel-WiFi slapd[526]: EQUALITY
May  6 01:47:13 Pinel-WiFi slapd[526]: end get_filter 0
May  6 01:47:13 Pinel-WiFi slapd[526]: conn=56 op=0 SRCH base="ou=utilisateurs,dc=pinel-wifi,dc=org" scope=2 filter="(pager=00:0A:E6:A7:27:CC)"
[...]
I cut the end, uninteresting I think.

I got this log by replacing manually 
$filter = "pager=$mac";
by this :
$filter = "pager=00:0A:E6:A7:27:CC"; 



Actual result:
--------------
And if I leave the original:
$filter = "pager=$mac";

that is what my openldap server recieve :
May  6 01:48:56 Pinel-WiFi slapd[341]: conn=58 fd=14 ACCEPT from IP=127.0.0.1:32868 (IP=0.0.0.0:389)
May  6 01:48:56 Pinel-WiFi slapd[526]: begin get_filter
May  6 01:48:56 Pinel-WiFi slapd[526]: EQUALITY
May  6 01:48:56 Pinel-WiFi slapd[526]: end get_filter 0
May  6 01:48:56 Pinel-WiFi slapd[526]: conn=58 op=0 SRCH base="ou=utilisateurs,dc=pinel-wifi,dc=org" scope=2 filter="(?=undefined)"
[...]
I cut the end too.

As you can see, there is a "(?=undefined)" in the filter field, which, I think, shouldn't be here. I tought that was a bug, so that's why I reported it.