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Bot prevention

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This commit is contained in:
Savetheinternet 2011-02-17 22:03:52 +11:00
parent fab3618afe
commit 7622e84b62
5 changed files with 137 additions and 2 deletions
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101
inc/functions.php
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@ -634,6 +634,105 @@
}
}
function createHiddenInputs() {
global $config;
$inputs = Array();
shuffle($config['spam']['hidden_input_names']);
$hidden_input_names_x = 0;
$input_count = rand($config['spam']['hidden_inputs_min'], $config['spam']['hidden_inputs_max']);
for($x=0;$x<$input_count;$x++) {
if(rand(0, 2) == 0 || $hidden_input_names_x < 0) {
// Use an obscure name
$name = substr(base64_encode(sha1(rand())), 0, rand(2, 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 = -1;
}
if(rand(0, 2) == 0) {
// Value must be null
$inputs[$name] = '';
} elseif(rand(0, 4) == 0) {
// Numeric value
$inputs[$name] = rand(0, 100);
} else {
// Obscure value
$inputs[$name] = substr(base64_encode(sha1(rand())), 0, rand(2, 40));
}
}
$content = '';
foreach($inputs as $name => $value) {
$content .= '<input type="hidden" name="' . htmlspecialchars($name) . '" value="' . htmlspecialchars($value) . '" />' . "\n ";
}
// Create a hash to validate it after
// This is the tricky part.
// First, sort the keys in alphabetical order (A-Z)
ksort($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);
// Append it to the HTML
$content .= '<input type="hidden" name="hash" value="' . $hash . '" />';
return $content;
}
function checkSpam() {
global $config;
if(!isset($_POST['hash']))
return true;
$hash = $_POST['hash'];
// 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);
return $hash != $_hash;
}
function buildIndex() {
global $board, $config;
sql_open();
@ -648,6 +747,7 @@
$content['pages'] = $pages;
$content['pages'][$page-1]['selected'] = true;
$content['btn'] = getPageButtons($content['pages']);
$content['hidden_inputs'] = createHiddenInputs();
@file_put_contents($filename, Element('index.html', $content)) or error("Couldn't write to file.");
if(isset($md5) && $md5 == md5_file($filename)) {
@ -837,6 +937,7 @@
'index' => $config['root'],
'id' => $id,
'mod' => $mod,
'hidden_inputs' => $content['hidden_inputs'] = createHiddenInputs(),
'return' => ($mod ? '?' . $board['url'] . $config['file_index'] : $config['root'] . $board['uri'] . '/' . $config['file_index'])
));