<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * Plugin to enable LDAP Authentication
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Plugin
 * @package   StatusNet
 * @author    Craig Andrews <candrews@integralblue.com>
 * @copyright 2009 Craig Andrews http://candrews.integralblue.com
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link      http://status.net/
 */

if (!defined('STATUSNET') && !defined('LACONICA')) {
    exit(1);
}

require_once 'Net/LDAP2.php';

class LdapAuthenticationPlugin extends AuthenticationPlugin
{
    public $host=null;
    public $port=null;
    public $version=null;
    public $starttls=null;
    public $binddn=null;
    public $bindpw=null;
    public $basedn=null;
    public $options=null;
    public $filter=null;
    public $scope=null;
    public $password_encoding=null;
    public $attributes=array();

    function onInitializePlugin(){
        parent::onInitializePlugin();
        if(!isset($this->host)){
            throw new Exception("must specify a host");
        }
        if(!isset($this->basedn)){
            throw new Exception("must specify a basedn");
        }
        if(!isset($this->attributes['nickname'])){
            throw new Exception("must specify a nickname attribute");
        }
        if(!isset($this->attributes['username'])){
            throw new Exception("must specify a username attribute");
        }
        if($this->password_changeable && (! isset($this->attributes['password']) || !isset($this->password_encoding))){
            throw new Exception("if password_changeable is set, the password attribute and password_encoding must also be specified");
        }
    }

    function onAutoload($cls)
    {   
        switch ($cls)
        {
         case 'MemcacheSchemaCache':
            require_once(INSTALLDIR.'/plugins/LdapAuthentication/MemcacheSchemaCache.php');
            return false;
        }
    }

    function onEndShowPageNotice($action)
    {
        $name = $action->trimmed('action');
        $instr = false;

        switch ($name)
        {
         case 'register':
            if($this->autoregistration) {
                $instr = 'Have an LDAP account? Use your standard username and password.';
            }
            break;
         case 'login':
            $instr = 'Have an LDAP account? Use your standard username and password.';
            break;
         default:
            return true;
        }

        if($instr) {
            $output = common_markup_to_html($instr);
            $action->raw($output);
        }
        return true;
    }
    
    //---interface implementation---//

    function checkPassword($username, $password)
    {
        $entry = $this->ldap_get_user($username);
        if(!$entry){
            return false;
        }else{
            $config = $this->ldap_get_config();
            $config['binddn']=$entry->dn();
            $config['bindpw']=$password;
            if($this->ldap_get_connection($config)){
                return true;
            }else{
                return false;
            }
        }
    }

    function autoRegister($username, $nickname)
    {
        if(is_null($nickname)){
            $nickname = $username;
        }
        $entry = $this->ldap_get_user($username,$this->attributes);
        if($entry){
            $registration_data = array();
            foreach($this->attributes as $sn_attribute=>$ldap_attribute){
                $registration_data[$sn_attribute]=$entry->getValue($ldap_attribute,'single');
            }
            if(isset($registration_data['email']) && !empty($registration_data['email'])){
                $registration_data['email_confirmed']=true;
            }
            $registration_data['nickname'] = $nickname;
            //set the database saved password to a random string.
            $registration_data['password']=common_good_rand(16);
            return User::register($registration_data);
        }else{
            //user isn't in ldap, so we cannot register him
            return false;
        }
    }

    function changePassword($username,$oldpassword,$newpassword)
    {
        if(! isset($this->attributes['password']) || !isset($this->password_encoding)){
            //throw new Exception(_('Sorry, changing LDAP passwords is not supported at this time'));
            return false;
        }
        $entry = $this->ldap_get_user($username);
        if(!$entry){
            return false;
        }else{
            $config = $this->ldap_get_config();
            $config['binddn']=$entry->dn();
            $config['bindpw']=$oldpassword;
            if($ldap = $this->ldap_get_connection($config)){
                $entry = $this->ldap_get_user($username,array(),$ldap);
                
                $newCryptedPassword = $this->hashPassword($newpassword, $this->password_encoding);
                if ($newCryptedPassword===false) {
                    return false;
                }
                if($this->password_encoding=='ad') {
                    //TODO I believe this code will work once this bug is fixed: http://pear.php.net/bugs/bug.php?id=16796
                    $oldCryptedPassword = $this->hashPassword($oldpassword, $this->password_encoding);
                    $entry->delete( array($this->attributes['password'] => $oldCryptedPassword ));
                }
                $entry->replace( array($this->attributes['password'] => $newCryptedPassword ), true);
                if( Net_LDAP2::isError($entry->upate()) ) {
                    return false;
                }
                return true;
            }else{
                return false;
            }
        }

        return false;
    }

    function suggestNicknameForUsername($username)
    {
        $entry = $this->ldap_get_user($username, $this->attributes);
        if(!$entry){
            //this really shouldn't happen
            $nickname = $username;
        }else{
            $nickname = $entry->getValue($this->attributes['nickname'],'single');
            if(!$nickname){
                $nickname = $username;
            }
        }
        return common_nicknamize($nickname);
    }
    
    //---utility functions---//
    function ldap_get_config(){
        $config = array();
        $keys = array('host','port','version','starttls','binddn','bindpw','basedn','options','filter','scope');
        foreach($keys as $key){
            $value = $this->$key;
            if($value!==null){
                $config[$key]=$value;
            }
        }
        return $config;
    }
    
    function ldap_get_connection($config = null){
        if($config == null && isset($this->default_ldap)){
            return $this->default_ldap;
        }
        
        //cannot use Net_LDAP2::connect() as StatusNet uses
        //PEAR::setErrorHandling(PEAR_ERROR_CALLBACK, 'handleError');
        //PEAR handling can be overridden on instance objects, so we do that.
        $ldap = new Net_LDAP2(isset($config)?$config:$this->ldap_get_config());
        $ldap->setErrorHandling(PEAR_ERROR_RETURN);
        $err=$ldap->bind();
        if (Net_LDAP2::isError($err)) {
            // if we were called with a config, assume caller will handle
            // incorrect username/password (LDAP_INVALID_CREDENTIALS)
            if (isset($config) && $err->getCode() == 0x31) {
                return null;
            }
            throw new Exception('Could not connect to LDAP server: '.$err->getMessage());
        }
        if($config == null) $this->default_ldap=$ldap;

        $c = common_memcache();
        if (!empty($c)) {
            $cacheObj = new MemcacheSchemaCache(
                array('c'=>$c,
                   'cacheKey' => common_cache_key('ldap_schema:' . crc32(serialize($config)))));
            $ldap->registerSchemaCache($cacheObj);
        }
        return $ldap;
    }
    
    /**
     * get an LDAP entry for a user with a given username
     * 
     * @param string $username
     * $param array $attributes LDAP attributes to retrieve
     * @return string DN
     */
    function ldap_get_user($username,$attributes=array(),$ldap=null){
        if($ldap==null) {
            $ldap = $this->ldap_get_connection();
        }
        $filter = Net_LDAP2_Filter::create($this->attributes['username'], 'equals',  $username);
        $options = array(
            'attributes' => $attributes
        );
        $search = $ldap->search($this->basedn, $filter, $options);
        
        if (PEAR::isError($search)) {
            common_log(LOG_WARNING, 'Error while getting DN for user: '.$search->getMessage());
            return false;
        }

        $searchcount = $search->count();
        if($searchcount == 0) {
            return false;
        }else if($searchcount == 1) {
            $entry = $search->shiftEntry();
            return $entry;
        }else{
            common_log(LOG_WARNING, 'Found ' . $searchcount . ' ldap user with the username: ' . $username);
            return false;
        }
    }
    
    /**
     * Code originaly from the phpLDAPadmin development team
     * http://phpldapadmin.sourceforge.net/
     *
     * Hashes a password and returns the hash based on the specified enc_type.
     *
     * @param string $passwordClear The password to hash in clear text.
     * @param string $encodageType Standard LDAP encryption type which must be one of
     *        crypt, ext_des, md5crypt, blowfish, md5, sha, smd5, ssha, or clear.
     * @return string The hashed password.
     *
     */

    function hashPassword( $passwordClear, $encodageType ) 
    {
        $encodageType = strtolower( $encodageType );
        switch( $encodageType ) {
            case 'crypt': 
                $cryptedPassword = '{CRYPT}' . crypt($passwordClear,$this->randomSalt(2)); 
                break;
                
            case 'ext_des':
                // extended des crypt. see OpenBSD crypt man page.
                if ( ! defined( 'CRYPT_EXT_DES' ) || CRYPT_EXT_DES == 0 ) {return FALSE;} //Your system crypt library does not support extended DES encryption.
                $cryptedPassword = '{CRYPT}' . crypt( $passwordClear, '_' . $this->randomSalt(8) );
                break;

            case 'md5crypt':
                if( ! defined( 'CRYPT_MD5' ) || CRYPT_MD5 == 0 ) {return FALSE;} //Your system crypt library does not support md5crypt encryption.
                $cryptedPassword = '{CRYPT}' . crypt( $passwordClear , '$1$' . $this->randomSalt(9) );
                break;

            case 'blowfish':
                if( ! defined( 'CRYPT_BLOWFISH' ) || CRYPT_BLOWFISH == 0 ) {return FALSE;} //Your system crypt library does not support blowfish encryption.
                $cryptedPassword = '{CRYPT}' . crypt( $passwordClear , '$2a$12$' . $this->randomSalt(13) ); // hardcoded to second blowfish version and set number of rounds
                break;

            case 'md5':
                $cryptedPassword = '{MD5}' . base64_encode( pack( 'H*' , md5( $passwordClear) ) );
                break;

            case 'sha':
                if( function_exists('sha1') ) {
                    // use php 4.3.0+ sha1 function, if it is available.
                    $cryptedPassword = '{SHA}' . base64_encode( pack( 'H*' , sha1( $passwordClear) ) );
                } elseif( function_exists( 'mhash' ) ) {
                    $cryptedPassword = '{SHA}' . base64_encode( mhash( MHASH_SHA1, $passwordClear) );
                } else {
                    return FALSE; //Your PHP install does not have the mhash() function. Cannot do SHA hashes.
                }
                break;

            case 'ssha':
                if( function_exists( 'mhash' ) && function_exists( 'mhash_keygen_s2k' ) ) {
                    mt_srand( (double) microtime() * 1000000 );
                    $salt = mhash_keygen_s2k( MHASH_SHA1, $passwordClear, substr( pack( "h*", md5( mt_rand() ) ), 0, 8 ), 4 );
                    $cryptedPassword = "{SSHA}".base64_encode( mhash( MHASH_SHA1, $passwordClear.$salt ).$salt );
                } else {
                    return FALSE; //Your PHP install does not have the mhash() function. Cannot do SHA hashes.
                }
                break;

            case 'smd5':
                if( function_exists( 'mhash' ) && function_exists( 'mhash_keygen_s2k' ) ) {
                    mt_srand( (double) microtime() * 1000000 );
                    $salt = mhash_keygen_s2k( MHASH_MD5, $passwordClear, substr( pack( "h*", md5( mt_rand() ) ), 0, 8 ), 4 );
                    $cryptedPassword = "{SMD5}".base64_encode( mhash( MHASH_MD5, $passwordClear.$salt ).$salt );
                } else {
                    return FALSE; //Your PHP install does not have the mhash() function. Cannot do SHA hashes.
                }
                break;

            case 'ad':
                $cryptedPassword = '';
                $passwordClear = "\"" . $passwordClear . "\"";
                $len = strlen($passwordClear);
                for ($i = 0; $i < $len; $i++) {
                    $cryptedPassword .= "{$passwordClear{$i}}\000";
                }

            case 'clear':
            default:
                $cryptedPassword = $passwordClear;
        }

        return $cryptedPassword;
    }

    /**
     * Code originaly from the phpLDAPadmin development team
     * http://phpldapadmin.sourceforge.net/
     *
     * Used to generate a random salt for crypt-style passwords. Salt strings are used
     * to make pre-built hash cracking dictionaries difficult to use as the hash algorithm uses
     * not only the user's password but also a randomly generated string. The string is
     * stored as the first N characters of the hash for reference of hashing algorithms later.
     *
     * --- added 20021125 by bayu irawan <bayuir@divnet.telkom.co.id> ---
     * --- ammended 20030625 by S C Rigler <srigler@houston.rr.com> ---
     *
     * @param int $length The length of the salt string to generate.
     * @return string The generated salt string.
     */
     
    function randomSalt( $length ) 
    {
        $possible = '0123456789'.
            'abcdefghijklmnopqrstuvwxyz'.
            'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.
            './';
        $str = "";
        mt_srand((double)microtime() * 1000000);

        while( strlen( $str ) < $length )
            $str .= substr( $possible, ( rand() % strlen( $possible ) ), 1 );

        return $str;
    }

    function onPluginVersion(&$versions)
    {
        $versions[] = array('name' => 'LDAP Authentication',
                            'version' => STATUSNET_VERSION,
                            'author' => 'Craig Andrews',
                            'homepage' => 'http://status.net/wiki/Plugin:LdapAuthentication',
                            'rawdescription' =>
                            _m('The LDAP Authentication plugin allows for StatusNet to handle authentication through LDAP.'));
        return true;
    }
}