<?php

# Copyright (c) 2009-2015 Yubico AB
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#   * Redistributions of source code must retain the above copyright
#     notice, this list of conditions and the following disclaimer.
#
#   * Redistributions in binary form must reproduce the above
#     copyright notice, this list of conditions and the following
#     disclaimer in the documentation and/or other materials provided
#     with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

require_once 'ykval-config.php';
require_once 'ykval-common.php';
require_once 'ykval-db.php';
require_once 'ykval-log.php';

function _get($arr, $key) {
    return array_key_exists($key, $arr) ? $arr[$key] : "?";
}

class SyncLib
{
    public $syncServers = array();
    public $dbConn = null;
    public $curlopts = array();

    public function __construct($logname='ykval-synclib')
    {
        $this->myLog = new Log($logname);
        global $baseParams;
        $this->syncServers = $baseParams['__YKVAL_SYNC_POOL__'];
        $this->db = Db::GetDatabaseHandle($baseParams, $logname);
        $this->isConnected=$this->db->connect();
        $this->server_nonce=md5(uniqid(rand()));

        if (array_key_exists('__YKVAL_SYNC_CURL_OPTS__', $baseParams))
        {
            $this->curlopts = $baseParams['__YKVAL_SYNC_CURL_OPTS__'];
        }
    }

    public function addField($name, $value)
    {
        $this->myLog->addField($name, $value);
        $this->db->addField($name, $value);
    }

    public function isConnected()
    {
        return $this->isConnected;
    }

    public function getNumberOfServers()
    {
        return count($this->syncServers);
    }

    public function getNumberOfValidAnswers()
    {
        if (isset($this->valid_answers))
            return $this->valid_answers;

        return 0;
    }

    public function getNumberOfAnswers()
    {
        if (isset($this->answers))
            return $this->answers;

        return 0;
    }

    public function getClientData($client)
    {
        $res = $this->db->customQuery("SELECT id, secret FROM clients WHERE active='1' AND id='" . $client . "'");
        $r = $this->db->fetchArray($res);
        $this->db->closeCursor($res);

        if ($r)
            return $r;

        return false;
    }

    public function getQueueLength()
    {
        return count($this->db->findBy('queue', null, null, null));
    }

    public function getQueueLengthByServer()
    {
        $counters = array();

        foreach ($this->syncServers as $server)
        {
            $counters[$server] = 0;
        }

        $result = $this->db->customQuery('SELECT server, COUNT(server) as count FROM queue GROUP BY server');

        while ($row = $this->db->fetchArray($result))
        {
            $counters[$row['server']] = $row['count'];
        }

        $this->db->closeCursor($result);

        return $counters;
    }

    public function queue($otpParams, $localParams)
    {
        $info = $this->createInfoString($otpParams, $localParams);
        $this->otpParams = $otpParams;
        $this->localParams = $localParams;

        $queued = time();
        $result = true;

        foreach ($this->syncServers as $server)
        {
            $arr = array(
                'queued' => $queued,
                'modified' => $otpParams['modified'],
                'otp' => $otpParams['otp'],
                'server' => $server,
                'server_nonce' => $this->server_nonce,
                'info' => $info
            );

            if (! $this->db->save('queue', $arr))
                $result = false;
        }

        return $result;
    }

    public function log($priority, $msg, $params=NULL)
    {
        if ($params)
            $msg .= ' modified=' . _get($params, 'modified') .
                 ' nonce=' . _get($params, 'nonce') .
                 ' yk_publicname=' . _get($params, 'yk_publicname') .
                 ' yk_counter=' . _get($params, 'yk_counter') .
                 ' yk_use=' . _get($params, 'yk_use') .
                 ' yk_high=' . _get($params, 'yk_high') .
                 ' yk_low=' . _get($params, 'yk_low');

        if ($this->myLog)
            $this->myLog->log($priority, $msg);
        else
            error_log("Warning: myLog uninitialized in ykval-synclib.php. Message is " . $msg);
    }

    public function getLocalParams($yk_publicname)
    {
        $this->log(LOG_DEBUG, "searching for yk_publicname $yk_publicname in local db");

        $res = $this->db->findBy('yubikeys', 'yk_publicname', $yk_publicname, 1);

        if (!$res)
        {
            $this->log(LOG_NOTICE, "Discovered new identity $yk_publicname");

            $this->db->save('yubikeys', array(
                'active' => 1,
                'created' => time(),
                'modified' => -1,
                'yk_publicname' => $yk_publicname,
                'yk_counter' => -1,
                'yk_use' => -1,
                'yk_low' => -1,
                'yk_high' => -1,
                'nonce' => '0000000000000000',
                'notes' => ''
            ));

            $res = $this->db->findBy('yubikeys', 'yk_publicname', $yk_publicname, 1);
        }

        if ($res)
        {
            $localParams = array(
                'modified' => $res['modified'],
                'nonce' => $res['nonce'],
                'active' => $res['active'],
                'yk_publicname' => $yk_publicname,
                'yk_counter' => $res['yk_counter'],
                'yk_use' => $res['yk_use'],
                'yk_high' => $res['yk_high'],
                'yk_low' => $res['yk_low']
            );

            $this->log(LOG_INFO, "yubikey found in db ", $localParams);
            return $localParams;
        }

        $this->log(LOG_NOTICE, "params for yk_publicname $yk_publicname not found in database");
        return false;
    }

    public function updateDbCounters($params)
    {
        if (!isset($params['yk_publicname']))
            return false;

        $arr = array(
            'modified' => $params['modified'],
            'yk_counter' => $params['yk_counter'],
            'yk_use' => $params['yk_use'],
            'yk_low' => $params['yk_low'],
            'yk_high' => $params['yk_high'],
            'nonce' => $params['nonce']
        );

        $condition = '('.$params['yk_counter'].'>yk_counter or ('.$params['yk_counter'].'=yk_counter and ' . $params['yk_use'] . '>yk_use))';

        if (! $this->db->conditionalUpdateBy('yubikeys', 'yk_publicname', $params['yk_publicname'], $arr, $condition))
        {
            $this->log(LOG_CRIT, 'failed to update internal DB with new counters');
            return false;
        }

        if ($this->db->rowCount() > 0)
            $this->log(LOG_INFO, 'updated database ', $params);
        else
            $this->log(LOG_INFO, 'database not updated', $params);

        return true;
    }

    public function countersHigherThan($p1, $p2)
    {
        if ($p1['yk_counter'] > $p2['yk_counter'])
            return true;

        if ($p1['yk_counter'] == $p2['yk_counter'] && $p1['yk_use'] > $p2['yk_use'])
            return true;

        return false;
    }

    public function countersHigherThanOrEqual($p1, $p2)
    {
        if ($p1['yk_counter'] > $p2['yk_counter'])
            return true;

        if ($p1['yk_counter'] == $p2['yk_counter'] && $p1['yk_use'] >= $p2['yk_use'])
            return true;

        return false;
    }

    public function countersEqual($p1, $p2)
    {
        return ($p1['yk_counter'] == $p2['yk_counter'] && $p1['yk_use'] == $p2['yk_use']);
    }

    // queue daemon
    public function reSync($older_than, $timeout)
    {
        $this->log(LOG_DEBUG, 'starting resync');

        /* Loop over all unique servers in queue */
        $queued_limit = time()-$older_than;
        $server_res = $this->db->customQuery("select distinct server from queue WHERE queued < " . $queued_limit . " or queued is null");
        $server_list = array();
        $mh = curl_multi_init();
        $ch = array();
        $entries = array();
        $handles = 0;
        $num_per_server = 4;
        $curlopts = $this->curlopts;

        while ($my_server = $this->db->fetchArray($server_res))
        {
            $server = $my_server['server'];
            $this->log(LOG_DEBUG, "Processing queue for server " . $server);

            $res = $this->db->customQuery("select * from queue WHERE (queued < " . $queued_limit . " or queued is null) and server='" . $server . "' LIMIT 1000");

            $list = array();

            while ($entry = $this->db->fetchArray($res))
            {
                $list[] = $entry;
            }
            $server_list[$server] = $list;

            $this->db->closeCursor($res);
        }
        $this->db->closeCursor($server_res);

        /* add up to n entries for each server we're going to sync */
        foreach ($server_list as $server) {
            $items = array_slice($server, 0, $num_per_server);
            $counter = 0;
            foreach ($items as $entry) {
                $label = "{$entry['server']}:$counter";
                $handle = curl_init();
                $ch[$label] = $handle;
                $counter++;
                $this->log(LOG_INFO, "server=" . $entry['server'] . ", server_nonce=" . $entry['server_nonce'] . ", info=" . $entry['info']);

                $url = $this->buildSyncUrl($entry);

                $curlopts[CURLOPT_PRIVATE] = $label;

                curl_settings($this, 'YK-VAL resync', $handle, $url, $timeout, $curlopts);
                $entries[$label] = $entry;
                curl_multi_add_handle($mh, $handle);
                $handles++;
            }
            $empty = array();
            array_splice($server, 0, $num_per_server, $empty);
            if(count($server) == 0) {
                unset($server_list[$entry['server']]);
            }
        }

        while($handles > 0) {
            while (curl_multi_exec($mh, $active) == CURLM_CALL_MULTI_PERFORM);

            while ($info = curl_multi_info_read($mh)) {
                $handle = $info['handle'];
                $server = strtok(curl_getinfo($handle, CURLINFO_EFFECTIVE_URL), "?");
                $label = curl_getinfo($handle, CURLINFO_PRIVATE);
                $entry = $entries[$label];
                $this->log(LOG_DEBUG, "handle indicated to be for $server.");
                curl_multi_remove_handle($mh, $handle);
                $handles--;
                if ($info['result'] === CURLE_OK) {
                    $response = curl_multi_getcontent($handle);
                    if (preg_match('/status=OK/', $response))
                    {
                        $resParams = $this->parseParamsFromMultiLineString($response);
                        $this->log(LOG_DEBUG, 'response contains ', $resParams);

                        /* Update database counters */
                        $this->updateDbCounters($resParams);

                        /* Retrieve info from entry info string */

                        /* This is the counter values we had in our database *before* processing the current OTP. */
                        $validationParams = $this->localParamsFromInfoString($entry['info']);

                        /* This is the data from the current OTP. */
                        $otpParams = $this->otpParamsFromInfoString($entry['info']);

                        /* Fetch current information from our database */
                        $localParams = $this->getLocalParams($otpParams['yk_publicname']);

                        $this->log(LOG_DEBUG, 'validation params: ', $validationParams);
                        $this->log(LOG_DEBUG, 'OTP params: ', $otpParams);

                        /* Check for warnings  */

                        if ($this->countersHigherThan($validationParams, $resParams))
                        {
                            $this->log(LOG_NOTICE, 'Remote server out of sync compared to counters at validation request time. ');
                        }

                        if ($this->countersHigherThan($resParams, $validationParams))
                        {
                            if ($this->countersEqual($resParams, $otpParams))
                            {
                                $this->log(LOG_INFO, 'Remote server had received the current counter values already. ');
                            }
                            else
                            {
                                $this->log(LOG_NOTICE, 'Local server out of sync compared to counters at validation request time. ');
                            }
                        }

                        if ($this->countersHigherThan($localParams, $resParams))
                        {
                            $this->log(LOG_WARNING, 'Remote server out of sync compared to current local counters.  ');
                        }

                        if ($this->countersHigherThan($resParams, $localParams))
                        {
                            $this->log(LOG_WARNING, 'Local server out of sync compared to current local counters. Local server updated. ');
                        }

                        if ($this->countersHigherThan($resParams, $otpParams))
                        {
                            $this->log(LOG_ERR, 'Remote server has higher counters than OTP. This response would have marked the OTP as invalid. ');
                        }
                        elseif ($this->countersEqual($resParams, $otpParams) && $resParams['nonce'] != $otpParams['nonce'])
                        {
                            $this->log(LOG_ERR, 'Remote server has equal counters as OTP and nonce differs. This response would have marked the OTP as invalid.');
                        }

                        /* Deletion */
                        $this->log(LOG_DEBUG, 'deleting queue entry with modified=' . $entry['modified'] .
                                   ' server_nonce=' . $entry['server_nonce'] .
                                   ' server=' . $entry['server']);

                        $this->db->deleteByMultiple('queue', array(
                            'modified' => $entry['modified'],
                            'server_nonce' => $entry['server_nonce'],
                            'server' => $entry['server']
                        ));

                    }
                    else if (preg_match('/status=BAD_OTP/', $response))
                    {
                        $this->log(LOG_WARNING, 'Remote server says BAD_OTP, pointless to try again, removing from queue.');
                        $this->db->deleteByMultiple('queue', array(
                            'modified' => $entry['modified'],
                            'server_nonce' => $entry['server_nonce'],
                            'server' => $entry['server']
                        ));
                    }
                    else
                    {
                        $this->log(LOG_ERR, 'Remote server refused our sync request. Check remote server logs.');
                    }

                    if (array_key_exists($server, $server_list)) {
                        $entry = array_shift($server_list[$server]);
                        if(count($server_list[$server]) == 0) {
                            $this->log(LOG_DEBUG, "All entries for $server synced.");
                            unset($server_list[$server]);
                        }
                        $this->log(LOG_INFO, "server=" . $entry['server'] . ", server_nonce=" . $entry['server_nonce'] . ", info=" . $entry['info']);

                        $url = $this->buildSyncUrl($entry);

                        $curlopts[CURLOPT_PRIVATE] = $label;
                        curl_settings($this, 'YK-VAL resync', $handle, $url, $timeout, $curlopts);
                        $entries[$label] = $entry;
                        curl_multi_add_handle($mh, $handle);
                        $handles++;
                    }
                } else {
                    $this->log(LOG_NOTICE, 'Timeout. Stopping queue resync for server ' . $entry['server']);
                    unset($server_list[$server]);
                }
            }
        }

        foreach ($ch as $handle) {
            curl_close($handle);
        }

        curl_multi_close($mh);

        return true;
    }

    // blocks verify requests
    public function sync($ans_req, $timeout=1)
    {
        // construct URLs
        $urls = array();
        $res = $this->db->findByMultiple('queue', array(
            'modified'     => $this->otpParams['modified'],
            'server_nonce' => $this->server_nonce
        ));
        foreach ($res as $row)
        {
            $urls[] = $this->buildSyncUrl($row);
        }

        // send out requests
        $ans_arr = retrieveURLasync('YK-VAL sync', $urls, $this->myLog, $ans_req, $match='status=OK', $returl=True, $timeout, $this->curlopts);

        if ($ans_arr === FALSE)
        {
            $this->log(LOG_WARNING, 'No responses from validation server pool');
            $ans_arr = array();
        }

        // parse responses
        $localParams = $this->localParams;

        $this->answers = count($ans_arr);
        $this->valid_answers = 0;

        foreach ($ans_arr as $answer)
        {
            // parse out parameters from each response
            $resParams=$this->parseParamsFromMultiLineString($answer);
            $this->log(LOG_DEBUG, 'local db contains ', $localParams);
            $this->log(LOG_DEBUG, 'response contains ', $resParams);
            $this->log(LOG_DEBUG, 'OTP contains ', $this->otpParams);

            // update internal DB (conditional)
            $this->updateDbCounters($resParams);

            /**
             * Check for warnings
             *
             * See https://developers.yubico.com/yubikey-val/doc/ServerReplicationProtocol.html
             *
             * NOTE: We use localParams for validationParams comparison since they are actually the
             *	same in this situation and we have them at hand.
             */

            if ($this->countersHigherThan($localParams, $resParams))
            {
                $this->log(LOG_NOTICE, 'Remote server out of sync');
            }

            if ($this->countersHigherThan($resParams, $localParams))
            {
                $this->log(LOG_NOTICE, 'Local server out of sync');
            }

            if ($this->countersEqual($resParams, $localParams) && $resParams['nonce'] != $localParams['nonce'])
            {
                $this->log(LOG_NOTICE, 'Servers out of sync. Nonce differs. ');
            }

            if ($this->countersEqual($resParams, $localParams) && $resParams['modified'] != $localParams['modified'])
            {
                $this->log(LOG_NOTICE, 'Servers out of sync. Modified differs. ');
            }

            if ($this->countersHigherThan($resParams, $this->otpParams))
            {
                $this->log(LOG_WARNING, 'OTP is replayed. Sync response counters higher than OTP counters.');
            }
            elseif ($this->countersEqual($resParams, $this->otpParams) && $resParams['nonce'] != $this->otpParams['nonce'])
            {
                $this->log(LOG_WARNING, 'OTP is replayed. Sync response counters equal to OTP counters and nonce differs.');
            }
            else
            {
                // the answer is ok since a REPLAY was not indicated
                $this->valid_answers++;
            }

            // delete entry from table
            $this->deleteQueueEntry($answer);
        }

        /**
         * NULL queued_time for remaining entries in queue, to allow
         *	daemon to take care of them as soon as possible.
         */
        $this->db->updateBy('queue', 'server_nonce', $this->server_nonce, array('queued'=>NULL));

        /**
         * Return true if valid answers equals required answers.
         *	Since we only obtain the required amount of answers from
         *	retrieveAsync this indicates that all answers were actually valid.
         *	Otherwise, return false.
         */
        if ($this->valid_answers == $ans_req)
            return true;

        return false;
    }

    private function createInfoString($otpParams, $localParams)
    {
        # FIXME &local_counter
        return 'yk_publicname=' . $otpParams['yk_publicname'] .
                                '&yk_counter=' . $otpParams['yk_counter'] .
                                '&yk_use=' . $otpParams['yk_use'] .
                                '&yk_high=' . $otpParams['yk_high'] .
                                '&yk_low=' . $otpParams['yk_low'] .
                                '&nonce=' . $otpParams['nonce'] .
                                ',local_counter=' . $localParams['yk_counter'] .
                                '&local_use=' . $localParams['yk_use'];
    }

    private function otpParamsFromInfoString($info)
    {
        $out = explode(',', $info);
        parse_str($out[0], $params);
        return $params;
    }

    private function otpPartFromInfoString($info)
    {
        $out = explode(',', $info);
        return $out[0];
    }

    private function localParamsFromInfoString($info)
    {
        $out = explode(',', $info);
        parse_str($out[1], $params);

        return array(
            'yk_counter' => $params['local_counter'],
            'yk_use' => $params['local_use']
        );
    }

    private function parseParamsFromMultiLineString($str)
    {
        $i = preg_match("/^modified=(-1|[0-9]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse modified value: $str");
        }
        $resParams['modified']=$out[1];

        $i = preg_match("/^yk_publicname=([cbdefghijklnrtuv]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse publicname value: $str");
        }
        $resParams['yk_publicname']=$out[1];

        $i = preg_match("/^yk_counter=(-1|[0-9]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse counter value: $str");
        }
        $resParams['yk_counter']=$out[1];

        $i = preg_match("/^yk_use=(-1|[0-9]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse use value: $str");
        }
        $resParams['yk_use']=$out[1];

        $i = preg_match("/^yk_high=(-1|[0-9]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse high value: $str");
        }
        $resParams['yk_high']=$out[1];

        $i = preg_match("/^yk_low=(-1|[0-9]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse low value: $str");
        }
        $resParams['yk_low']=$out[1];

        $i = preg_match("/^nonce=([[:alnum:]]+)/m", $str, $out);
        if ($i != 1) {
            $this->log(LOG_ALERT, "cannot parse nonce value: $str");
        }
        $resParams['nonce']=$out[1];

        return $resParams;
    }

    private function deleteQueueEntry($answer)
    {
        preg_match('/url=(.*)\?/', $answer, $out);
        $server = $out[1];

        $this->log(LOG_INFO, "deleting server=" . $server .
                   " modified=" . $this->otpParams['modified'] .
                   " server_nonce=" . $this->server_nonce);

        $this->db->deleteByMultiple('queue', array(
            'modified' => $this->otpParams['modified'],
            'server_nonce' => $this->server_nonce,
            'server' => $server
        ));
    }

    private function buildSyncUrl($entry)
    {
        return $entry['server'] .
                                "?otp=" . $entry['otp'] .
                                "&modified=" . $entry['modified'] .
                                "&" . $this->otpPartFromInfoString($entry['info']);
    }
}