<?php
namespace App\Auth;

use Cake\Auth\BaseAuthenticate;
use Cake\Network\Request;
use Cake\Network\Response;

class LdapAuthenticate extends BaseAuthenticate
{

    protected $_host = 'your_host';

    public function authenticate(Request $request, Response $response)
    {
        $username = $request->data['username'];
        $password = $request->data['password'];
        $ds       = @ldap_connect($this->_host);
        if (!$ds) {
            throw \Cake\Error\FatalErrorException('Unable to connect to LDAP host.');
        }
        $basedn   = "cn=Users,dc=your_dc";
        $dn       = "cn=$username, " . $basedn;
        $ldapbind = ldap_bind($ds, $dn, $password);
        if (!$ldapbind) {
            return false;
        }

        $entry = ldap_first_entry($ldapbind);
        $attrs = ldap_get_attributes($ldapbind, $entry);
        $user  = [];
        // Loop
        for ($i = 0; $i < $attrs["count"]; $i++) {
            $user[$attrs[$i]] = ldap_values($ldapbind, $entry, $attrs[$i])[0];
        }
        // Then close it and return the authenticated user
        ldap_unbind($ldapbind);
        return $user;
    }
}