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better anti-bot check

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Michael Save 2012-04-12 17:20:49 +10:00
parent 96ffd9eb3b
commit dd0f421015
5 changed files with 274 additions and 178 deletions
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inc/anti-bot.php Normal file
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<?php
/*
* Copyright (c) 2010-2012 Tinyboard Development Group
*/
if(realpath($_SERVER['SCRIPT_FILENAME']) == str_replace('\\', '/', __FILE__)) {
// You cannot request this file directly.
exit;
}
$hidden_inputs_twig = array();
class AntiBot {
public $inputs = array(), $index = 0;
private $salt;
public static function randomString($length, $uppercase = false, $special_chars = false) {
$chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
if($uppercase)
$chars .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
if($special_chars)
$chars .= ' ~!@#$%^&*()_+,./;\'[]\\{}|:"<>?=-` ';
$chars = str_split($chars);
$ch = array();
// fill up $ch until we reach $length
while(count($ch) < $length) {
$n = $length - count($ch);
$keys = array_rand($chars, $n > count($chars) ? count($chars) : $n);
if($n == 1) {
$ch[] = $chars[$keys];
break;
}
shuffle($keys);
foreach($keys as $key)
$ch[] = $chars[$key];
}
$chars = $ch;
return implode('', $chars);
}
public static function make_confusing($string) {
$chars = str_split($string);
foreach($chars as &$c) {
if(rand(0, 2) != 0)
continue;
$c = mb_encode_numericentity($c, array(0, 0xffff, 0, 0xffff), 'UTF-8');
}
return implode('', $chars);
}
public function __construct(array $salt = array()) {
global $config;
if(!empty($salt)) {
// 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']);
$hidden_input_names_x = 0;
for($x = 0; $x < $input_count ; $x++) {
if($hidden_input_names_x === false || rand(0, 2) == 0) {
// 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++];
if($hidden_input_names_x >= count($config['spam']['hidden_input_names']))
$hidden_input_names_x = false;
}
if(rand(0, 2) == 0) {
// Value must be null
$this->inputs[$name] = '';
} elseif(rand(0, 4) == 0) {
// Numeric value
$this->inputs[$name] = (string)rand(0, 100);
} else {
// Obscure value
$this->inputs[$name] = $this->randomString(rand(5, 100));
}
}
}
public function html($count = false) {
$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>'
);
$html = '';
if($count == 0) {
// all elements
$inputs = array_slice($this->inputs, $this->index);
} else {
$inputs = array_slice($this->inputs, $this->index, $count);
}
$this->index += count($inputs);
foreach($inputs as $name => $value) {
$element = false;
while(!$element) {
$element = $elements[array_rand($elements)];
if(strpos($element, 'textarea') !== false && $value == '') {
// There have been some issues with mobile web browsers and empty <textarea>'s.
$element = false;
}
}
$element = str_replace('%name%', utf8tohtml($name), $element);
if(rand(0, 2) == 0)
$value = $this->make_confusing($value);
else
$value = utf8tohtml($value);
$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);
$hash = '';
// Iterate through each input
foreach($inputs as $name => $value) {
$hash .= $name . '=' . $value;
}
// Add a salt to the hash
$hash .= $config['cookies']['salt'];
// Use SHA1 for the hash
return sha1($hash . $this->salt);
}
};;
function hiddenInputs(array $salt, $print_the_rest = false) {
global $hidden_inputs_twig;
$salt_str = implode(':', $salt);
if(!isset($hidden_inputs_twig[$salt_str]))
$hidden_inputs_twig[$salt_str] = new AntiBot($salt);
if($print_the_rest)
return $hidden_inputs_twig[$salt_str]->html(0);
else
return $hidden_inputs_twig[$salt_str]->html(rand(1, 5));
}
function hiddenInputsHash(array $salt) {
global $hidden_inputs_twig;
$salt_str = implode(':', $salt);
if(!isset($hidden_inputs_twig[$salt_str]))
$hidden_inputs_twig[$salt_str] = new AntiBot($salt);
return $hidden_inputs_twig[$salt_str]->hash();
}
function checkSpam(array $extra_salt = array()) {
global $config;
if(!isset($_POST['hash']))
return true;
$hash = $_POST['hash'];
if(!empty($extra_salt)) {
// create a salted hash of the "extra salt"
$extra_salt = implode(':', $extra_salt);
} else {
$extra_salt = '';
}
// Reconsturct the $inputs array
$inputs = array();
foreach($_POST as $name => $value) {
if(in_array($name, $config['spam']['valid_inputs']))
continue;
$inputs[$name] = $value;
}
// Sort the inputs in alphabetical order (A-Z)
ksort($inputs);
$_hash = '';
// Iterate through each input
foreach($inputs as $name => $value) {
$_hash .= $name . '=' . $value;
}
// Add a salt to the hash
$_hash .= $config['cookies']['salt'];
// Use SHA1 for the hash
$_hash = sha1($_hash . $extra_salt);
return $hash != $_hash;
}