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I manage two WordPress installations with multi-site (previously WP MU). Logins via LDAP would be ideal. I hadn’t had any luck making the existing LDAP plugins to work with Novell eDirectory. However, we just moved to use Active Directory (AD) and so I retried some of the plugins. I now have Simple LDAP Login (plugin) working. Since I’ve installed it on a multi-site installation I made some further modifications to the plugin. Here’s how I did it.

I wanted the plugin to run on any blog so I put it in the mu-plugins folder. Anything in wp-content/mu-plugins will be run on every blog in the system and doesn’t show up in the ‘Plugins’ menu to activate / de-activate. After copying the plugin into the mu-plugin you also have to create a file in mu-plugins that includes a specific plugin file since WP won’t include folders in mu-plugins like it does with the plugins folder — it only executes the files in the mu-plugins folder itself. To cater for this, you must change the following line in Simple-LDAP-Login.php:

	require_once( WP_PLUGIN_DIR."/simple-ldap-login/adLDAP.php");

to:

	require_once( WPMU_PLUGIN_DIR."/simple-ldap-login/adLDAP.php");

I wanted the configuration for the LDAP plugin to be only accessible to Super Admin users to that individual users of any of the blogs in the system, even administrators wouldn’t be able to mess around with the settings for the pluing. To do this, you need to find the call to add_options_page() in Simple-LDAP-Login.php and change it to:

    add_options_page("Simple LDAP Login", "Simple LDAP Login", 'update_core', "simple-ldap-login", "simpleldap_menu");

The key here is the third argument. This requires that in order for a user to see this options page the user must have ‘update_core’ capability. This capability is possessed by Super Admins. See more about WordPress Roles and Capabilities.

Finally, I created a quick PHP script that will update the blog options sitewide. Point it at a WordPress database, and edit it to adjust settings that you want and this will update the options on all blogs (with exceptions if you like) on a WordPress installation. The script is rough and ready and there no protection for SQL injection, so be careful if you’re thinking about hooking this up to some user input.

<?php
	// a quick script to update blog options in a WordPress 3.0 multi-site environment.

	$conn = mysql_connection(...); // insert your db connection info here.

	// options to set. this just alters options in the wp_*_options table
	// with these 'option_name' => array('value' => 'option_value', 'autoload' => 'autoload')

	$options = array(
		// format: '<option-name>' => array('value' => '<option_value>', 'autoload' => '<yes|no>'),
		// examples
		"simpleldap_account_suffix" => array('value'=>'@domain', 'autoload'=>'yes'),
		"show_avatars" => array('value'=>0, 'autoload'=>'yes'), // hide avatars.
		);

	// blog id's to exclude.
	$wp_id_exceptions = array();	

	foreach( get_option_tables( $wp_id_exceptions ) as $table ) {
		echo "processing TABLE ". $table."\n";
		update_options($options,$table);
	}

function get_option_tables($wp_id_exceptions) {
	global $db;
	$query = " show tables like 'wp_%_options'";
	$result = mysql_query($query);
	if ($result) {
		$tables = array();
		while($row = mysql_fetch_row($result)) {
			$add = 1;
			foreach($wp_id_exceptions as $id) {
				if ($row[0] == "wp_{$id}_options") {
					$add = 0;
				}
			}
			if ($add) {
				$tables[] = $row[0];
			}
		}
	}
	return $tables;
}

function update_options($options,$table) {
	global $db;
	foreach($options as $opt_name => $info) {
		$insert = "insert into $table (option_name, option_value, autoload) values ('$opt_name','{$info['value']}','{$info['autoload']}')";
		$insert_result = mysql_query($insert);

		if ($insert_result) {
			echo "\t inserted OPTION $opt_name = {$info['value']}\n";
		}
		else if (mysql_errno() == 1062) {
			// attempt to update what's already there.
			$update_query = "update $table set option_value = '".$info['value']."', autoload = '{$info['autoload']}' where option_name = '$opt_name'	\n";
			$update_result = mysql_query($update_query);
			if ($update_result) {
				if (mysql_affected_rows()) {
					echo "\t updated OPTION $opt_name = {$info['value']}\n";
				}
				else {
					echo "\t no change OPTION $opt_name = {$info['value']}\n";
				}
			}
			else {
				echo mysql_errno() . " " . mysql_error()."\n";
			}
		}
		else {
			echo mysql_errno() . " " . mysql_error(). "\n";
		}

	}

}

?>

I wrote this script to keep the LDAP plugin up-to-date across blogs, but it has already proven really useful for other purposes.