lainchan/inc/anti-bot.php

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<?php
/*
* Copyright (c) 2010-2012 Tinyboard Development Group
*/
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if (realpath($_SERVER['SCRIPT_FILENAME']) == str_replace('\\', '/', __FILE__)) {
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// You cannot request this file directly.
exit;
}
$hidden_inputs_twig = array();
class AntiBot {
public $salt, $inputs = array(), $index = 0;
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public static function randomString($length, $uppercase = false, $special_chars = false) {
$chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
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if ($uppercase)
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$chars .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
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if ($special_chars)
$chars .= ' ~!@#$%^&*()_+,./;\'[]\\{}|:<>?=-` ';
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$chars = str_split($chars);
$ch = array();
// fill up $ch until we reach $length
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while (count($ch) < $length) {
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$n = $length - count($ch);
$keys = array_rand($chars, $n > count($chars) ? count($chars) : $n);
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if ($n == 1) {
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$ch[] = $chars[$keys];
break;
}
shuffle($keys);
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foreach ($keys as $key)
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$ch[] = $chars[$key];
}
$chars = $ch;
return implode('', $chars);
}
public static function make_confusing($string) {
$chars = str_split($string);
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foreach ($chars as &$c) {
if (rand(0, 2) != 0)
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$c = utf8tohtml($c);
else
$c = mb_encode_numericentity($c, array(0, 0xffff, 0, 0xffff), 'UTF-8');
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}
return implode('', $chars);
}
public function __construct(array $salt = array()) {
global $config;
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if (!empty($salt)) {
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// create a salted hash of the "extra salt"
$this->salt = implode(':', $salt);
} else {
$this->salt = '';
}
shuffle($config['spam']['hidden_input_names']);
$input_count = rand($config['spam']['hidden_inputs_min'], $config['spam']['hidden_inputs_max']);
$hidden_input_names_x = 0;
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for ($x = 0; $x < $input_count ; $x++) {
if ($hidden_input_names_x === false || rand(0, 2) == 0) {
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// Use an obscure name
$name = $this->randomString(rand(10, 40));
} else {
// Use a pre-defined confusing name
$name = $config['spam']['hidden_input_names'][$hidden_input_names_x++];
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if ($hidden_input_names_x >= count($config['spam']['hidden_input_names']))
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$hidden_input_names_x = false;
}
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if (rand(0, 2) == 0) {
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// Value must be null
$this->inputs[$name] = '';
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} elseif (rand(0, 4) == 0) {
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// Numeric value
$this->inputs[$name] = (string)rand(0, 100);
} else {
// Obscure value
$this->inputs[$name] = $this->randomString(rand(5, 100), true, true);
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}
}
}
public function html($count = false) {
global $config;
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$elements = array(
'<input type="hidden" name="%name%" value="%value%">',
'<input type="hidden" value="%value%" name="%name%">',
'<input style="display:none" type="text" name="%name%" value="%value%">',
'<input style="display:none" type="text" value="%value%" name="%name%">',
'<span style="display:none"><input type="text" name="%name%" value="%value%"></span>',
'<div style="display:none"><input type="text" name="%name%" value="%value%"></div>',
'<div style="display:none"><input type="text" name="%name%" value="%value%"></div>',
'<textarea style="display:none" name="%name%">%value%</textarea>',
'<textarea name="%name%" style="display:none">%value%</textarea>'
);
$html = '';
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if ($count === false) {
$count = rand(1, count($this->inputs) / 15);
}
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if ($count === true) {
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// all elements
$inputs = array_slice($this->inputs, $this->index);
} else {
$inputs = array_slice($this->inputs, $this->index, $count);
}
$this->index += count($inputs);
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foreach ($inputs as $name => $value) {
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$element = false;
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while (!$element) {
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$element = $elements[array_rand($elements)];
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if (strpos($element, 'textarea') !== false && $value == '') {
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// There have been some issues with mobile web browsers and empty <textarea>'s.
$element = false;
}
}
$element = str_replace('%name%', utf8tohtml($name), $element);
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if (rand(0, 2) == 0)
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$value = $this->make_confusing($value);
else
$value = utf8tohtml($value);
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if (strpos($element, 'textarea') === false)
$value = str_replace('"', '&quot;', $value);
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$element = str_replace('%value%', $value, $element);
$html .= $element;
}
return $html;
}
public function hash() {
global $config;
// This is the tricky part: create a hash to validate it after
// First, sort the keys in alphabetical order (A-Z)
$inputs = $this->inputs;
ksort($inputs);
$hash = '';
// Iterate through each input
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foreach ($inputs as $name => $value) {
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$hash .= $name . '=' . $value;
}
// Add a salt to the hash
$hash .= $config['cookies']['salt'];
// Use SHA1 for the hash
return sha1($hash . $this->salt);
}
}
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function _create_antibot($board, $thread) {
global $config;
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$antibot = new AntiBot(array($board, $thread));
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query('DELETE FROM `antispam` WHERE `expires` < UNIX_TIMESTAMP()') or error(db_error());
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if ($thread)
$query = prepare('UPDATE `antispam` SET `expires` = UNIX_TIMESTAMP() + :expires WHERE `board` = :board AND `thread` = :thread AND `expires` IS NULL');
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else
$query = prepare('UPDATE `antispam` SET `expires` = UNIX_TIMESTAMP() + :expires WHERE `board` = :board AND `thread` IS NULL AND `expires` IS NULL');
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$query->bindValue(':board', $board);
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if ($thread)
$query->bindValue(':thread', $thread);
$query->bindValue(':expires', $config['spam']['hidden_inputs_expire']);
$query->execute() or error(db_error($query));
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$query = prepare('INSERT INTO `antispam` VALUES (:board, :thread, :hash, UNIX_TIMESTAMP(), NULL, 0)');
$query->bindValue(':board', $board);
$query->bindValue(':thread', $thread);
$query->bindValue(':hash', $antibot->hash());
$query->execute() or error(db_error($query));
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return $antibot;
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}
function checkSpam(array $extra_salt = array()) {
global $config, $pdo;
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if (!isset($_POST['hash']))
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return true;
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$hash = $_POST['hash'];
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if (!empty($extra_salt)) {
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// create a salted hash of the "extra salt"
$extra_salt = implode(':', $extra_salt);
} else {
$extra_salt = '';
}
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// Reconsturct the $inputs array
$inputs = array();
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foreach ($_POST as $name => $value) {
if (in_array($name, $config['spam']['valid_inputs']))
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continue;
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$inputs[$name] = $value;
}
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// Sort the inputs in alphabetical order (A-Z)
ksort($inputs);
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$_hash = '';
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// Iterate through each input
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foreach ($inputs as $name => $value) {
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$_hash .= $name . '=' . $value;
}
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// Add a salt to the hash
$_hash .= $config['cookies']['salt'];
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// Use SHA1 for the hash
$_hash = sha1($_hash . $extra_salt);
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if ($hash != $_hash)
return true;
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$query = prepare('SELECT `passed` FROM `antispam` WHERE `hash` = :hash');
$query->bindValue(':hash', $hash);
$query->execute() or error(db_error($query));
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if ((($passed = $query->fetchColumn(0)) === false) || ($passed > $config['spam']['hidden_inputs_max_pass'])) {
// there was no database entry for this hash. most likely expired.
return true;
}
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return $hash;
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}
function incrementSpamHash($hash) {
$query = prepare('UPDATE `antispam` SET `passed` = `passed` + 1 WHERE `hash` = :hash');
$query->bindValue(':hash', $hash);
$query->execute() or error(db_error($query));
}