<?php
/**
 * Name: LDAP Authenticate
 * Description: Authenticate a user against an LDAP directory
 * Version: 1.0
 * Author: Mike Macgirvin <zot:mike@zothub.com>
 */
 
/**
 * 
 * Module: LDAP Authenticate
 *
 * Authenticate a user against an LDAP directory
 * Useful for Windows Active Directory and other LDAP-based organisations
 * to maintain a single password across the organisation.
 *
 * Optionally authenticates only if a member of a given group in the directory.
 *
 * The person must have registered with Friendica using the normal registration 
 * procedures in order to have a Friendica user record, contact, and profile.
 *
 * Note when using with Windows Active Directory: you may need to set TLS_CACERT in your site
 * ldap.conf file to the signing cert for your LDAP server. 
 * 
 * The required configuration options for this module may be set in the .htconfig.php file
 * e.g.:
 *
 * $a->config['ldapauth']['ldap_server'] = 'host.example.com';
 *
 * Parameters:
 * ldap_server = DNS hostname of LDAP service, or URL e.g. ldaps://example.com
 * ldap_binddn = LDAP DN of an account to bind with to search LDAP
 * ldap_bindpw = password for LDAP bind DN
 * ldap_searchdn = base DN for the search root of the LDAP directory
 * ldap_userattr = the name of the attribute containing the username, e.g. SAMAccountName
 * ldap_group = (optional) DN of group to check membership
 * create_account = (optional) 1 or 0 (default), automatically create Hubzilla accounts based on the LDAP 'mail' attribute
 *
 */


function ldapauth_load() {
	register_hook('authenticate', 'addon/ldapauth/ldapauth.php', 'ldapauth_hook_authenticate');
}


function ldapauth_unload() {
	unregister_hook('authenticate', 'addon/ldapauth/ldapauth.php', 'ldapauth_hook_authenticate');
}


function ldapauth_hook_authenticate($a,&$b) {
	$mail = '';
	if(ldapauth_authenticate($b['username'],$b['password'],$mail)) {
		$results = q("SELECT * FROM account where account_email = '%s' OR account_email = '%s'  AND account_flags in (0,1) limit 1",
			dbesc($b['username']), dbesc($mail)
		);
		if((! $results) && ($mail) && intval(get_config('ldapauth','create_account')) == 1) {
			require_once('include/account.php');
			$acct = create_account(array('email' => $mail, 'password' => random_string()));			
			if($acct['success']) {
				logger('ldapauth: Created account for ' . $b['username'] . ' using ' . $mail);
				info(t('An account has been created for you.'));
				$b['user_record'] = $acct['account'];
				$b['authenticated'] = 1;
			}

		} elseif(intval(get_config('ldapauth','create_account')) != 1 && (! $results)) {
                  logger('ldapauth: User '.$b['username'].' authenticated but no db-record and. Rejecting auth.');
		  notice( t('Authentication successful but rejected: account creation is disabled.'));
		  return;
		}
		if($results) {
			logger('ldapauth: Login success for ' . $b['username']);
			$b['user_record'] = $results[0];
			$b['authenticated'] = 1;
		}
	}
	return;
}


function ldapauth_authenticate($username,$password,&$mail) {
    logger('ldapauth: Searching user '.$username.'.');
    $ldap_server   = get_config('ldapauth','ldap_server');
    $ldap_binddn   = get_config('ldapauth','ldap_binddn');
    $ldap_bindpw   = get_config('ldapauth','ldap_bindpw');
    $ldap_searchdn = get_config('ldapauth','ldap_searchdn');
    $ldap_userattr = get_config('ldapauth','ldap_userattr');
    $ldap_group    = get_config('ldapauth','ldap_group');

    if(empty($password)) {
        logger('ldapauth: Empty Password not allowed.');
        return false;
    }

    if(!function_exists('ldap_connect')
       || empty($ldap_server)) {
            logger('ldapauth: PHP-LDAP fail or no server set.');
            return false;
    }

    $connect = @ldap_connect($ldap_server);

    if(! $connect) {
	logger('ldapauth: Unable to connect to server');
        return false;
    }

    @ldap_set_option($connect, LDAP_OPT_PROTOCOL_VERSION,3);
    @ldap_set_option($connect, LDAP_OPT_REFERRALS, 0);
    if((@ldap_bind($connect,$ldap_binddn,$ldap_bindpw)) === false) {
	logger('ldapauth: Unable to bind to server. Check credentials of binddn.');
        return false;
    }

    $res = @ldap_search($connect,$ldap_searchdn, $ldap_userattr . '=' . $username, array('mail'));

    if(! $res) {
	logger('ldapauth: User '.$username.' not found.');
        return false;
    }

    $id = @ldap_first_entry($connect,$res);

    if(! $id) {
	logger('ldapauth: User '.$username.' found but unable to load data.');
        return false;
    }

	// get primary email

	$mail = '';

	$attrs = @ldap_get_attributes($connect,$id);
	if($attrs['count'] && $attrs['mail']) {
		if(is_array($attrs['mail']))
			$mail = $attrs['mail'][0];
		else
			$mail = $attrs['mail'];
	}

    $dn = @ldap_get_dn($connect,$id);

    if(! @ldap_bind($connect,$dn,$password)) {
	logger('ldapauth: User '.$username.' provided wrong credentials.');
        return false;
    }

    if(empty($ldap_group)) {
	logger('ldapauth: User '.$username.' authenticated.');
        return true;
    }

    $r = @ldap_compare($connect,$ldap_group,'member',$dn);
    if ($r === -1) {
        $err = @ldap_error($connect);
        $eno = @ldap_errno($connect);
        @ldap_close($connect);

        if ($eno === 32) {
            logger('ldapauth: access control group Does Not Exist');
            return false;
        }
        elseif ($eno === 16) {
            logger('ldapauth: membership attribute does not exist in access control group');
            return false;
        }
        else {
            logger('ldapauth: error: ' . $err);
            return false;
        }
    }
    elseif ($r === false) {
	logger('ldapauth: User '.$username.' is not in the allowed group.');
        @ldap_close($connect);
        return false;
    }
//    logger('ldapauth: User '.$username.' authenticated and in allowed group.');
  return true;
}