<?php

use dokuwiki\Extension\AuthPlugin;
use dokuwiki\PassHash;
use dokuwiki\Utf8\Sort;

/**
 * LDAP authentication backend
 *
 * @license   GPL 2 (http://www.gnu.org/licenses/gpl.html)
 * @author    Andreas Gohr <andi@splitbrain.org>
 * @author    Chris Smith <chris@jalakaic.co.uk>
 * @author    Jan Schumann <js@schumann-it.com>
 */
class auth_plugin_authldap extends AuthPlugin
{
    /* @var resource $con holds the LDAP connection */
    protected $con;

    /* @var int $bound What type of connection does already exist? */
    protected $bound = 0; // 0: anonymous, 1: user, 2: superuser

    /* @var array $users User data cache */
    protected $users;

    /* @var array $pattern User filter pattern */
    protected $pattern;

    /**
     * Constructor
     */
    public function __construct()
    {
        parent::__construct();

        // ldap extension is needed
        if (!function_exists('ldap_connect')) {
            $this->debug("LDAP err: PHP LDAP extension not found.", -1, __LINE__, __FILE__);
            $this->success = false;
            return;
        }

        // Add the capabilities to change the password
        $this->cando['modPass'] = $this->getConf('modPass');
    }

    /**
     * Check user+password
     *
     * Checks if the given user exists and the given
     * plaintext password is correct by trying to bind
     * to the LDAP server
     *
     * @param string $user
     * @param string $pass
     * @return  bool
     * @author  Andreas Gohr <andi@splitbrain.org>
     */
    public function checkPass($user, $pass)
    {
        // reject empty password
        if (empty($pass)) return false;
        if (!$this->openLDAP()) return false;

        // indirect user bind
        if ($this->getConf('binddn') && $this->getConf('bindpw')) {
            // use superuser credentials
            if (!@ldap_bind($this->con, $this->getConf('binddn'), conf_decodeString($this->getConf('bindpw')))) {
                $this->debug('LDAP bind as superuser: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                return false;
            }
            $this->bound = 2;
        } elseif (
            $this->getConf('binddn') &&
            $this->getConf('usertree') &&
            $this->getConf('userfilter')
        ) {
            // special bind string
            $dn = $this->makeFilter(
                $this->getConf('binddn'),
                ['user' => $user, 'server' => $this->getConf('server')]
            );
        } elseif (strpos($this->getConf('usertree'), '%{user}')) {
            // direct user bind
            $dn = $this->makeFilter(
                $this->getConf('usertree'),
                ['user' => $user, 'server' => $this->getConf('server')]
            );
        } elseif (!@ldap_bind($this->con)) {
            // Anonymous bind
            msg("LDAP: can not bind anonymously", -1);
            $this->debug('LDAP anonymous bind: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
            return false;
        }

        // Try to bind to with the dn if we have one.
        if (!empty($dn)) {
            // User/Password bind
            if (!@ldap_bind($this->con, $dn, $pass)) {
                $this->debug("LDAP: bind with $dn failed", -1, __LINE__, __FILE__);
                $this->debug('LDAP user dn bind: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                return false;
            }
            $this->bound = 1;
            return true;
        } else {
            // See if we can find the user
            $info = $this->fetchUserData($user, true);
            if (empty($info['dn'])) {
                return false;
            } else {
                $dn = $info['dn'];
            }

            // Try to bind with the dn provided
            if (!@ldap_bind($this->con, $dn, $pass)) {
                $this->debug("LDAP: bind with $dn failed", -1, __LINE__, __FILE__);
                $this->debug('LDAP user bind: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                return false;
            }
            $this->bound = 1;
            return true;
        }
    }

    /**
     * Return user info
     *
     * Returns info about the given user needs to contain
     * at least these fields:
     *
     * name string  full name of the user
     * mail string  email addres of the user
     * grps array   list of groups the user is in
     *
     * This LDAP specific function returns the following
     * addional fields:
     *
     * dn     string  distinguished name (DN)
     * uid    string  Posix User ID
     * inbind bool    for internal use - avoid loop in binding
     *
     * @param string $user
     * @param bool $requireGroups (optional) - ignored, groups are always supplied by this plugin
     * @return  array containing user data or false
     * @author  <evaldas.auryla@pheur.org>
     * @author  Stephane Chazelas <stephane.chazelas@emerson.com>
     * @author  Steffen Schoch <schoch@dsb.net>
     *
     * @author  Andreas Gohr <andi@splitbrain.org>
     * @author  Trouble
     * @author  Dan Allen <dan.j.allen@gmail.com>
     */
    public function getUserData($user, $requireGroups = true)
    {
        return $this->fetchUserData($user);
    }

    /**
     * @param string $user
     * @param bool $inbind authldap specific, true if in bind phase
     * @return  array containing user data or false
     */
    protected function fetchUserData($user, $inbind = false)
    {
        global $conf;
        if (!$this->openLDAP()) return [];

        // force superuser bind if wanted and not bound as superuser yet
        if ($this->getConf('binddn') && $this->getConf('bindpw') && $this->bound < 2) {
            // use superuser credentials
            if (!@ldap_bind($this->con, $this->getConf('binddn'), conf_decodeString($this->getConf('bindpw')))) {
                $this->debug('LDAP bind as superuser: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                return [];
            }
            $this->bound = 2;
        } elseif ($this->bound == 0 && !$inbind) {
            // in some cases getUserData is called outside the authentication workflow
            // eg. for sending email notification on subscribed pages. This data might not
            // be accessible anonymously, so we try to rebind the current user here
            [$loginuser, $loginsticky, $loginpass] = auth_getCookie();
            if ($loginuser && $loginpass) {
                $loginpass = auth_decrypt($loginpass, auth_cookiesalt(!$loginsticky, true));
                $this->checkPass($loginuser, $loginpass);
            }
        }

        $info = [];
        $info['user'] = $user;
        $this->debug('LDAP user to find: ' . hsc($info['user']), 0, __LINE__, __FILE__);

        $info['server'] = $this->getConf('server');
        $this->debug('LDAP Server: ' . hsc($info['server']), 0, __LINE__, __FILE__);

        //get info for given user
        $base = $this->makeFilter($this->getConf('usertree'), $info);
        if ($this->getConf('userfilter')) {
            $filter = $this->makeFilter($this->getConf('userfilter'), $info);
        } else {
            $filter = "(ObjectClass=*)";
        }

        $this->debug('LDAP Filter: ' . hsc($filter), 0, __LINE__, __FILE__);

        $this->debug('LDAP user search: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
        $this->debug('LDAP search at: ' . hsc($base . ' ' . $filter), 0, __LINE__, __FILE__);
        $sr = $this->ldapSearch($this->con, $base, $filter, $this->getConf('userscope'), $this->getConf('attributes'));
        if ($sr === false) {
            $this->debug('User ldap_search failed. Check configuration.', 0, __LINE__, __FILE__);
            return false;
        }

        $result = @ldap_get_entries($this->con, $sr);

        // if result is not an array
        if (!is_array($result)) {
            // no objects found
            $this->debug('LDAP search returned non-array result: ' . hsc(print($result)), -1, __LINE__, __FILE__);
            return [];
        }

        // Don't accept more or less than one response
        if ($result['count'] != 1) {
            $this->debug(
                'LDAP search returned ' . hsc($result['count']) . ' results while it should return 1!',
                -1,
                __LINE__,
                __FILE__
            );
            //for($i = 0; $i < $result["count"]; $i++) {
            //$this->_debug('result: '.hsc(print_r($result[$i])), 0, __LINE__, __FILE__);
            //}
            return [];
        }

        $this->debug('LDAP search found single result !', 0, __LINE__, __FILE__);

        $user_result = $result[0];
        ldap_free_result($sr);

        // general user info
        $info['dn'] = $user_result['dn'];
        $info['gid'] = $user_result['gidnumber'][0] ?? null;
        $info['mail'] = $user_result['mail'][0];
        $info['name'] = $user_result['cn'][0];
        $info['grps'] = [];

        // overwrite if other attribs are specified.
        if (is_array($this->getConf('mapping'))) {
            foreach ($this->getConf('mapping') as $localkey => $key) {
                if (is_array($key)) {
                    // use regexp to clean up user_result
                    // $key = array($key=>$regexp), only handles the first key-value
                    $regexp = current($key);
                    $key = key($key);
                    if ($user_result[$key]) foreach ($user_result[$key] as $grpkey => $grp) {
                        if ($grpkey !== 'count' && preg_match($regexp, $grp, $match)) {
                            if ($localkey == 'grps') {
                                $info[$localkey][] = $match[1];
                            } else {
                                $info[$localkey] = $match[1];
                            }
                        }
                    }
                } else {
                    $info[$localkey] = $user_result[$key][0];
                }
            }
        }
        $user_result = array_merge($info, $user_result);

        //get groups for given user if grouptree is given
        if ($this->getConf('grouptree') || $this->getConf('groupfilter')) {
            $base = $this->makeFilter($this->getConf('grouptree'), $user_result);
            $filter = $this->makeFilter($this->getConf('groupfilter'), $user_result);
            $sr = $this->ldapSearch(
                $this->con,
                $base,
                $filter,
                $this->getConf('groupscope'),
                [$this->getConf('groupkey')]
            );
            $this->debug('LDAP group search: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
            $this->debug('LDAP search at: ' . hsc($base . ' ' . $filter), 0, __LINE__, __FILE__);

            if (!$sr) {
                msg("LDAP: Reading group memberships failed", -1);
                return [];
            }
            $result = ldap_get_entries($this->con, $sr);
            ldap_free_result($sr);

            if (is_array($result)) foreach ($result as $grp) {
                if (!empty($grp[$this->getConf('groupkey')])) {
                    $group = $grp[$this->getConf('groupkey')];
                    if (is_array($group)) {
                        $group = $group[0];
                    } else {
                        $this->debug('groupkey did not return a detailled result', 0, __LINE__, __FILE__);
                    }
                    if ($group === '') continue;

                    $this->debug('LDAP usergroup: ' . hsc($group), 0, __LINE__, __FILE__);
                    $info['grps'][] = $group;
                }
            }
        }

        // always add the default group to the list of groups
        if (!$info['grps'] || !in_array($conf['defaultgroup'], $info['grps'])) {
            $info['grps'][] = $conf['defaultgroup'];
        }
        return $info;
    }

    /**
     * Definition of the function modifyUser in order to modify the password
     *
     * @param string $user nick of the user to be changed
     * @param array $changes array of field/value pairs to be changed (password will be clear text)
     * @return  bool   true on success, false on error
     */
    public function modifyUser($user, $changes)
    {

        // open the connection to the ldap
        if (!$this->openLDAP()) {
            $this->debug('LDAP cannot connect: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
            return false;
        }

        // find the information about the user, in particular the "dn"
        $info = $this->getUserData($user, true);
        if (empty($info['dn'])) {
            $this->debug('LDAP cannot find your user dn', 0, __LINE__, __FILE__);
            return false;
        }
        $dn = $info['dn'];

        // find the old password of the user
        [$loginuser, $loginsticky, $loginpass] = auth_getCookie();
        if ($loginuser !== null) { // the user is currently logged in
            $secret = auth_cookiesalt(!$loginsticky, true);
            $pass = auth_decrypt($loginpass, $secret);

            // bind with the ldap
            if (!@ldap_bind($this->con, $dn, $pass)) {
                $this->debug(
                    'LDAP user bind failed: ' . hsc($dn) . ': ' . hsc(ldap_error($this->con)),
                    0,
                    __LINE__,
                    __FILE__
                );
                return false;
            }
        } elseif ($this->getConf('binddn') && $this->getConf('bindpw')) {
            // we are changing the password on behalf of the user (eg: forgotten password)
            // bind with the superuser ldap
            if (!@ldap_bind($this->con, $this->getConf('binddn'), conf_decodeString($this->getConf('bindpw')))) {
                $this->debug('LDAP bind as superuser: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                return false;
            }
        } else {
            return false; // no otherway
        }

        // Generate the salted hashed password for LDAP
        $phash = new PassHash();
        $hash = $phash->hash_ssha($changes['pass']);

        // change the password
        if (!@ldap_mod_replace($this->con, $dn, ['userpassword' => $hash])) {
            $this->debug(
                'LDAP mod replace failed: ' . hsc($dn) . ': ' . hsc(ldap_error($this->con)),
                0,
                __LINE__,
                __FILE__
            );
            return false;
        }

        return true;
    }

    /**
     * Most values in LDAP are case-insensitive
     *
     * @return bool
     */
    public function isCaseSensitive()
    {
        return false;
    }

    /**
     * Bulk retrieval of user data
     *
     * @param int $start index of first user to be returned
     * @param int $limit max number of users to be returned
     * @param array $filter array of field/pattern pairs, null for no filter
     * @return  array of userinfo (refer getUserData for internal userinfo details)
     * @author  Dominik Eckelmann <dokuwiki@cosmocode.de>
     */
    public function retrieveUsers($start = 0, $limit = 0, $filter = [])
    {
        if (!$this->openLDAP()) return [];

        if (is_null($this->users)) {
            // Perform the search and grab all their details
            if ($this->getConf('userfilter')) {
                $all_filter = str_replace('%{user}', '*', $this->getConf('userfilter'));
            } else {
                $all_filter = "(ObjectClass=*)";
            }
            $sr = ldap_search($this->con, $this->getConf('usertree'), $all_filter);
            $entries = ldap_get_entries($this->con, $sr);
            $users_array = [];
            $userkey = $this->getConf('userkey');
            for ($i = 0; $i < $entries["count"]; $i++) {
                $users_array[] = $entries[$i][$userkey][0];
            }
            Sort::asort($users_array);
            $result = $users_array;
            if (!$result) return [];
            $this->users = array_fill_keys($result, false);
        }
        $i = 0;
        $count = 0;
        $this->constructPattern($filter);
        $result = [];

        foreach ($this->users as $user => &$info) {
            if ($i++ < $start) {
                continue;
            }
            if ($info === false) {
                $info = $this->getUserData($user);
            }
            if ($this->filter($user, $info)) {
                $result[$user] = $info;
                if (($limit > 0) && (++$count >= $limit)) break;
            }
        }
        return $result;
    }

    /**
     * Make LDAP filter strings.
     *
     * Used by auth_getUserData to make the filter
     * strings for grouptree and groupfilter
     *
     * @param string $filter ldap search filter with placeholders
     * @param array $placeholders placeholders to fill in
     * @return  string
     * @author  Troels Liebe Bentsen <tlb@rapanden.dk>
     */
    protected function makeFilter($filter, $placeholders)
    {
        preg_match_all("/%{([^}]+)/", $filter, $matches, PREG_PATTERN_ORDER);
        //replace each match
        foreach ($matches[1] as $match) {
            //take first element if array
            if (is_array($placeholders[$match])) {
                $value = $placeholders[$match][0];
            } else {
                $value = $placeholders[$match];
            }
            $value = $this->filterEscape($value);
            $filter = str_replace('%{' . $match . '}', $value, $filter);
        }
        return $filter;
    }

    /**
     * return true if $user + $info match $filter criteria, false otherwise
     *
     * @param string $user the user's login name
     * @param array $info the user's userinfo array
     * @return bool
     * @author Chris Smith <chris@jalakai.co.uk>
     *
     */
    protected function filter($user, $info)
    {
        foreach ($this->pattern as $item => $pattern) {
            if ($item == 'user') {
                if (!preg_match($pattern, $user)) return false;
            } elseif ($item == 'grps') {
                if (!count(preg_grep($pattern, $info['grps']))) return false;
            } elseif (!preg_match($pattern, $info[$item])) {
                return false;
            }
        }
        return true;
    }

    /**
     * Set the filter pattern
     *
     * @param $filter
     * @return void
     * @author Chris Smith <chris@jalakai.co.uk>
     *
     */
    protected function constructPattern($filter)
    {
        $this->pattern = [];
        foreach ($filter as $item => $pattern) {
            $this->pattern[$item] = '/' . str_replace('/', '\/', $pattern) . '/i'; // allow regex characters
        }
    }

    /**
     * Escape a string to be used in a LDAP filter
     *
     * Ported from Perl's Net::LDAP::Util escape_filter_value
     *
     * @param string $string
     * @return string
     * @author Andreas Gohr
     */
    protected function filterEscape($string)
    {
        // see https://github.com/adldap/adLDAP/issues/22
        return preg_replace_callback(
            '/([\x00-\x1F\*\(\)\\\\])/',
            static fn($matches) => "\\" . implode("", unpack("H2", $matches[1])),
            $string
        );
    }

    /**
     * Opens a connection to the configured LDAP server and sets the wanted
     * option on the connection
     *
     * @author  Andreas Gohr <andi@splitbrain.org>
     */
    protected function openLDAP()
    {
        if ($this->con) return true; // connection already established

        if ($this->getConf('debug')) {
            ldap_set_option(null, LDAP_OPT_DEBUG_LEVEL, 7);
        }

        $this->bound = 0;

        $port = $this->getConf('port');
        $bound = false;
        $servers = explode(',', $this->getConf('server'));
        foreach ($servers as $server) {
            $server = trim($server);
            $this->con = @ldap_connect($server, $port);
            if (!$this->con) {
                continue;
            }

            /*
             * When OpenLDAP 2.x.x is used, ldap_connect() will always return a resource as it does
             * not actually connect but just initializes the connecting parameters. The actual
             * connect happens with the next calls to ldap_* funcs, usually with ldap_bind().
             *
             * So we should try to bind to server in order to check its availability.
             */

            //set protocol version and dependend options
            if ($this->getConf('version')) {
                if (
                    !@ldap_set_option(
                        $this->con,
                        LDAP_OPT_PROTOCOL_VERSION,
                        $this->getConf('version')
                    )
                ) {
                    msg('Setting LDAP Protocol version ' . $this->getConf('version') . ' failed', -1);
                    $this->debug('LDAP version set: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                } else {
                    //use TLS (needs version 3)
                    if ($this->getConf('starttls')) {
                        if (!@ldap_start_tls($this->con)) {
                            msg('Starting TLS failed', -1);
                            $this->debug('LDAP TLS set: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                        }
                    }
                    // needs version 3
                    if ($this->getConf('referrals') > -1) {
                        if (
                            !@ldap_set_option(
                                $this->con,
                                LDAP_OPT_REFERRALS,
                                $this->getConf('referrals')
                            )
                        ) {
                            msg('Setting LDAP referrals failed', -1);
                            $this->debug('LDAP referal set: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                        }
                    }
                }
            }

            //set deref mode
            if ($this->getConf('deref')) {
                if (!@ldap_set_option($this->con, LDAP_OPT_DEREF, $this->getConf('deref'))) {
                    msg('Setting LDAP Deref mode ' . $this->getConf('deref') . ' failed', -1);
                    $this->debug('LDAP deref set: ' . hsc(ldap_error($this->con)), 0, __LINE__, __FILE__);
                }
            }
            /* As of PHP 5.3.0 we can set timeout to speedup skipping of invalid servers */
            if (defined('LDAP_OPT_NETWORK_TIMEOUT')) {
                ldap_set_option($this->con, LDAP_OPT_NETWORK_TIMEOUT, 1);
            }

            if ($this->getConf('binddn') && $this->getConf('bindpw')) {
                $bound = @ldap_bind($this->con, $this->getConf('binddn'), conf_decodeString($this->getConf('bindpw')));
                $this->bound = 2;
            } else {
                $bound = @ldap_bind($this->con);
            }
            if ($bound) {
                break;
            }
        }

        if (!$bound) {
            msg("LDAP: couldn't connect to LDAP server", -1);
            $this->debug(ldap_error($this->con), 0, __LINE__, __FILE__);
            return false;
        }

        $this->cando['getUsers'] = true;
        return true;
    }

    /**
     * Wraps around ldap_search, ldap_list or ldap_read depending on $scope
     *
     * @param resource $link_identifier
     * @param string $base_dn
     * @param string $filter
     * @param string $scope can be 'base', 'one' or 'sub'
     * @param null|array $attributes
     * @param int $attrsonly
     * @param int $sizelimit
     * @return resource
     * @author Andreas Gohr <andi@splitbrain.org>
     */
    protected function ldapSearch(
        $link_identifier,
        $base_dn,
        $filter,
        $scope = 'sub',
        $attributes = null,
        $attrsonly = 0,
        $sizelimit = 0
    ) {
        if (is_null($attributes)) $attributes = [];

        if ($scope == 'base') {
            return @ldap_read(
                $link_identifier,
                $base_dn,
                $filter,
                $attributes,
                $attrsonly,
                $sizelimit
            );
        } elseif ($scope == 'one') {
            return @ldap_list(
                $link_identifier,
                $base_dn,
                $filter,
                $attributes,
                $attrsonly,
                $sizelimit
            );
        } else {
            return @ldap_search(
                $link_identifier,
                $base_dn,
                $filter,
                $attributes,
                $attrsonly,
                $sizelimit
            );
        }
    }

    /**
     * Wrapper around msg() but outputs only when debug is enabled
     *
     * @param string $message
     * @param int $err
     * @param int $line
     * @param string $file
     * @return void
     */
    protected function debug($message, $err, $line, $file)
    {
        if (!$this->getConf('debug')) return;
        msg($message, $err, $line, $file);
    }
}
