LDAP 问题，ldap_bind 无效的 dn 语法

I am trying to create a function with php, so I can be able to connect to LDAP and find the desired information.

我的php代码如下:

$ldapconfig['host'] = "127.0.0.1";
$ldapconfig['port'] = NULL;
$ldapconfig['basedn'] = "dc=example,dc=com";
$ldapconfig['binddn'] = "user";
$ldapconfig['bindpw'] = "password";


function ldap_authenticate($user, $pass) {
global $ldapconfig;
ldap_set_option(NULL, LDAP_OPT_DEBUG_LEVEL, 7); 
if ($user != "" && $pass != "") {
    $ds=ldap_connect($ldapconfig['host'],$ldapconfig['port']);
    if(!ldap_set_option($ds, LDAP_OPT_PROTOCOL_VERSION, 3)) {
        return NULL;
    }
    ldap_set_option($ds, LDAP_OPT_REFERRALS, 0);
    ldap_bind( $ds, $ldapconfig['binddn'], $ldapconfig['bindpw']);
    $r = ldap_search( $ds, $ldapconfig['basedn'], 'sAMAccountName=' . $user);
    if ($r) {
        $result = ldap_get_entries( $ds, $r);
        if ($result[0]) {
            if (ldap_bind( $ds, $result[0]['dn'], $pass) ) {
                return $result[0]['mail'][0];
            }
        }
    }
}
return NULL;

当我尝试运行代码时，它给了我以下错误:ldap_bind 第 xxxx 行的 DN 语法无效该行如下:

ldap_bind( $ds, $ldapconfig['binddn'], $ldapconfig['bindpw']);