ldap_compare

(PHP 4 >= 4.0.2, PHP 5, PHP 7, PHP 8)

ldap_compare — Compare value of attribute found in entry specified with DN

Description

ldap_compare(
    LDAP\Connection $ldap,
    string $dn,
    string $attribute,
    string $value,
    ?array $controls = null
): bool|int

Compare value of attribute with value of same attribute in an LDAP directory entry.

Parameters

ldap: An LDAP\Connection instance, returned by ldap_connect().
dn: The distinguished name of an LDAP entity.
attribute: The attribute name.
value: The compared value.
controls: Array of LDAP Controls to send with the request.

Return Values

Returns true if value matches otherwise returns false. Returns -1 on error.

Changelog

Version	Description
8.1.0	The `ldap` parameter expects an LDAP\Connection instance now; previously, a valid `ldap link` resource was expected.
8.0.0	`controls` is nullable now; previously, it defaulted to `[]`.
7.3.0	Support for `controls` added

Examples

The following example demonstrates how to check whether or not given password matches the one defined in DN specified entry.

Example #1 Complete example of password check

<?php

$ds=ldap_connect("localhost");  // assuming the LDAP server is on this host

if ($ds) {

    // bind
    if (ldap_bind($ds)) {

        // prepare data
        $dn = "cn=Matti Meikku, ou=My Unit, o=My Company, c=FI";
        $value = "secretpassword";
        $attr = "password";

        // compare value
        $r=ldap_compare($ds, $dn, $attr, $value);

        if ($r === -1) {
            echo "Error: " . ldap_error($ds);
        } elseif ($r === true) {
            echo "Password correct.";
        } elseif ($r === false) {
            echo "Wrong guess! Password incorrect.";
        }

    } else {
        echo "Unable to bind to LDAP server.";
    }

    ldap_close($ds);

} else {
    echo "Unable to connect to LDAP server.";
}
?>

Notes

Warning

ldap_compare() can NOT be used to compare BINARY values!

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User Contributed Notes 4 notes

down

chuck+ldap at 2006 dot snew dot com ¶

20 years ago

Just a side note that this is not how you'd ever AUTHENTICATE someone, just an example code.

The common way to authenticate is to get the users name, use search and perhaps selection to the user to get her DN (single value) then attempt to BIND to the ldapserver using that dn and the offered password.  If it works, then it's the right password.

Note that the password offered MUST NOT BE EMPTY or many LDAPs will presume you meant to authenticate anonymously and it will succeed, leaving you thinking it's the right password.

down

oudejans at zeelandnet dot nl ¶

19 years ago

With PHP 4.3.* is Password no longer a valid attribute.. try to use userPassword

down

Brian Kerhin <kerhin at bigfoot dot com> ¶

23 years ago

Not probably, will.  With PHP 4.0.4 and openldap 1.2.9 this little script, even with the correct attributes for the password does not do the job.  Would superb if it did!

down

-1

334647 at swin dot edu dot au ¶

24 years ago

Interesting example. Apart from the fact that very few people would allow comaprisions of the password attribute for security reasons. The attribute name of "password" does not match the usual schemas.



The usual method of user id + password verification is to attempt to bind using the supplied credentials.



Ldap compare on password values will probably fail with ns directroy server and openldap v2+ becuase of server support for password hashing.

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