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<?php
/*
Question2Answer by Gideon Greenspan and contributors
http://www.question2answer.org/
Description: Monitoring and rate-limiting user actions (application level)
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
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 General Public License for more details.
More about this license: http://www.question2answer.org/license.php
*/
if (!defined('QA_VERSION')) { // don't allow this page to be requested directly from browser
header('Location: ../../');
exit;
}
define('QA_LIMIT_QUESTIONS', 'Q');
define('QA_LIMIT_ANSWERS', 'A');
define('QA_LIMIT_COMMENTS', 'C');
define('QA_LIMIT_VOTES', 'V');
define('QA_LIMIT_REGISTRATIONS', 'R');
define('QA_LIMIT_LOGINS', 'L');
define('QA_LIMIT_UPLOADS', 'U');
define('QA_LIMIT_FLAGS', 'F');
define('QA_LIMIT_MESSAGES', 'M'); // i.e. private messages
define('QA_LIMIT_WALL_POSTS', 'W');
/**
* How many more times the logged in user (and requesting IP address) can perform an action this hour.
* @param string $action One of the QA_LIMIT_* constants defined above.
* @return int
*/
function qa_user_limits_remaining($action)
{
$userlimits = qa_db_get_pending_result('userlimits', qa_db_user_limits_selectspec(qa_get_logged_in_userid()));
$iplimits = qa_db_get_pending_result('iplimits', qa_db_ip_limits_selectspec(qa_remote_ip_address()));
return qa_limits_calc_remaining($action, @$userlimits[$action], @$iplimits[$action]);
}
/**
* Return how many more times user $userid and/or the requesting IP can perform $action (a QA_LIMIT_* constant) this hour.
* @deprecated Deprecated from 1.6.0; use `qa_user_limits_remaining($action)` instead.
* @param int $userid
* @param string $action
* @return mixed
*/
function qa_limits_remaining($userid, $action)
{
if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }
require_once QA_INCLUDE_DIR . 'db/limits.php';
$dblimits = qa_db_limits_get($userid, qa_remote_ip_address(), $action);
return qa_limits_calc_remaining($action, @$dblimits['user'], @$dblimits['ip']);
}
/**
* Calculate how many more times an action can be performed this hour by the user/IP.
* @param string $action One of the QA_LIMIT_* constants defined above.
* @param array $userlimits Limits for the user.
* @param array $iplimits Limits for the requesting IP.
* @return mixed
*/
function qa_limits_calc_remaining($action, $userlimits, $iplimits)
{
switch ($action) {
case QA_LIMIT_QUESTIONS:
$usermax = qa_opt('max_rate_user_qs');
$ipmax = qa_opt('max_rate_ip_qs');
break;
case QA_LIMIT_ANSWERS:
$usermax = qa_opt('max_rate_user_as');
$ipmax = qa_opt('max_rate_ip_as');
break;
case QA_LIMIT_COMMENTS:
$usermax = qa_opt('max_rate_user_cs');
$ipmax = qa_opt('max_rate_ip_cs');
break;
case QA_LIMIT_VOTES:
$usermax = qa_opt('max_rate_user_votes');
$ipmax = qa_opt('max_rate_ip_votes');
break;
case QA_LIMIT_REGISTRATIONS:
$usermax = 1; // not really relevant
$ipmax = qa_opt('max_rate_ip_registers');
break;
case QA_LIMIT_LOGINS:
$usermax = 1; // not really relevant
$ipmax = qa_opt('max_rate_ip_logins');
break;
case QA_LIMIT_UPLOADS:
$usermax = qa_opt('max_rate_user_uploads');
$ipmax = qa_opt('max_rate_ip_uploads');
break;
case QA_LIMIT_FLAGS:
$usermax = qa_opt('max_rate_user_flags');
$ipmax = qa_opt('max_rate_ip_flags');
break;
case QA_LIMIT_MESSAGES:
case QA_LIMIT_WALL_POSTS:
$usermax = qa_opt('max_rate_user_messages');
$ipmax = qa_opt('max_rate_ip_messages');
break;
default:
qa_fatal_error('Unknown limit code in qa_limits_calc_remaining: ' . $action);
break;
}
$period = (int)(qa_opt('db_time') / 3600);
return max(0, min(
$usermax - (@$userlimits['period'] == $period ? $userlimits['count'] : 0),
$ipmax - (@$iplimits['period'] == $period ? $iplimits['count'] : 0)
));
}
/**
* Determine whether the requesting IP address has been blocked from write operations.
* @return bool
*/
function qa_is_ip_blocked()
{
if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }
global $qa_curr_ip_blocked;
// return cached value early
if (isset($qa_curr_ip_blocked))
return $qa_curr_ip_blocked;
$qa_curr_ip_blocked = false;
$blockipclauses = qa_block_ips_explode(qa_opt('block_ips_write'));
$ip = qa_remote_ip_address();
foreach ($blockipclauses as $blockipclause) {
if (qa_block_ip_match($ip, $blockipclause)) {
$qa_curr_ip_blocked = true;
break;
}
}
return $qa_curr_ip_blocked;
}
/**
* Return an array of the clauses within $blockipstring, each of which can contain hyphens or asterisks
* @param string $blockipstring
* @return array
*/
function qa_block_ips_explode($blockipstring)
{
$blockipstring = preg_replace('/\s*\-\s*/', '-', $blockipstring); // special case for 'x.x.x.x - x.x.x.x'
return preg_split('/[^0-9A-Fa-f\.:\-\*]/', $blockipstring, -1, PREG_SPLIT_NO_EMPTY);
}
/**
* Checks if the IP address is matched by the individual block clause, which can contain a hyphen or asterisk
* @param string $ip The IP address
* @param string $blockipclause The IP/clause to check against, e.g. 127.0.0.*
* @return bool
*/
function qa_block_ip_match($ip, $blockipclause)
{
$ipv4 = filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false;
$blockipv4 = filter_var($blockipclause, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4) !== false;
// allow faster return if IP and blocked IP are plain IPv4 strings (IPv6 requires expanding)
if ($ipv4 && $blockipv4) {
return $ip === $blockipclause;
}
if (filter_var($ip, FILTER_VALIDATE_IP)) {
if (preg_match('/^(.*)\-(.*)$/', $blockipclause, $matches)) {
// match IP range
if (filter_var($matches[1], FILTER_VALIDATE_IP) && filter_var($matches[2], FILTER_VALIDATE_IP)) {
return qa_ip_between($ip, $matches[1], $matches[2]);
}
} elseif (strlen($blockipclause)) {
// normalize IPv6 addresses
if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
$ip = qa_ipv6_expand($ip);
$blockipclause = qa_ipv6_expand($blockipclause);
}
// expand wildcards; preg_quote misses hyphens but that is OK here
return preg_match('/^' . str_replace('\\*', '([0-9A-Fa-f]+)', preg_quote($blockipclause, '/')) . '$/', $ip) > 0;
}
}
return false;
}
/**
* Check if IP falls between two others.
* @param string $ip
* @param string $startip
* @param string $endip
* @return bool
*/
function qa_ip_between($ip, $startip, $endip)
{
$uip = unpack('C*', @inet_pton($ip));
$ustartip = unpack('C*', @inet_pton($startip));
$uendip = unpack('C*', @inet_pton($endip));
if (count($uip) != count($ustartip) || count($uip) != count($uendip))
return false;
foreach ($uip as $i => $byte) {
if ($byte < $ustartip[$i] || $byte > $uendip[$i]) {
return false;
}
}
return true;
}
/**
* Expands an IPv6 address (possibly containing wildcards), e.g. ::ffff:1 to 0000:0000:0000:0000:0000:0000:ffff:0001.
* Based on http://stackoverflow.com/a/12095836/753676
* @param string $ip The IP address to expand.
* @return string
*/
function qa_ipv6_expand($ip)
{
$ipv6_wildcard = false;
$wildcards = '';
$wildcards_matched = array();
if (strpos($ip, "*") !== false) {
$ipv6_wildcard = true;
}
if ($ipv6_wildcard) {
$wildcards = explode(":", $ip);
foreach ($wildcards as $index => $value) {
if ($value == "*") {
$wildcards_matched[] = count($wildcards) - 1 - $index;
$wildcards[$index] = "0";
}
}
$ip = implode($wildcards, ":");
}
$hex = unpack("H*hex", @inet_pton($ip));
$ip = substr(preg_replace("/([0-9A-Fa-f]{4})/", "$1:", $hex['hex']), 0, -1);
if ($ipv6_wildcard) {
$wildcards = explode(":", $ip);
foreach ($wildcards_matched as $value) {
$i = count($wildcards) - 1 - $value;
$wildcards[$i] = "*";
}
$ip = implode($wildcards, ":");
}
return $ip;
}
/**
* Called after a database write $action performed by a user identified by $userid and/or $cookieid.
* @param int $userid
* @param string $cookieid
* @param string $action
* @param int $questionid
* @param int $answerid
* @param int $commentid
*/
function qa_report_write_action($userid, $cookieid, $action, $questionid, $answerid, $commentid)
{
}
/**
* Take note for rate limits that a user and/or the requesting IP just performed an action.
* @param int|null $userid User performing the action.
* @param string $action One of the QA_LIMIT_* constants defined above.
* @return mixed
*/
function qa_limits_increment($userid, $action)
{
if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }
require_once QA_INCLUDE_DIR . 'db/limits.php';
$period = (int)(qa_opt('db_time') / 3600);
if (isset($userid))
qa_db_limits_user_add($userid, $action, $period, 1);
qa_db_limits_ip_add(qa_remote_ip_address(), $action, $period, 1);
}