<?php
/**
* ZeroBin
*
* a zero-knowledge paste bin
*
* @link http://sebsauvage.net/wiki/doku.php?id=php:zerobin
* @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
* @license http://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
* @version 0.19
*/
/**
* zerobin
*
* Controller, puts it all together.
*/
class zerobin
{
/**
* version
*
* @const string
*/
const VERSION = 'Alpha 0.19';
/**
* configuration array
*
* @access private
* @var array
*/
private $_conf = array(
'model' => 'zerobin_data',
);
/**
* data
*
* @access private
* @var string
*/
private $_data = '';
/**
* error message
*
* @access private
* @var string
*/
private $_error = '';
/**
* status message
*
* @access private
* @var string
*/
private $_status = '';
/**
* data storage model
*
* @access private
* @var zerobin_abstract
*/
private $_model;
/**
* constructor
*
* initializes and runs ZeroBin
*
* @access public
* @return void
*/
public function __construct()
{
if (version_compare(PHP_VERSION, '5.2.6') < 0)
throw new Exception('ZeroBin requires php 5.2.6 or above to work. Sorry.', 1);
// in case stupid admin has left magic_quotes enabled in php.ini
if (get_magic_quotes_gpc())
{
$_POST = array_map('filter::stripslashes_deep', $_POST);
$_GET = array_map('filter::stripslashes_deep', $_GET);
$_COOKIE = array_map('filter::stripslashes_deep', $_COOKIE);
}
// load config from ini file
$this->_init();
// create new paste or comment
if (!empty($_POST['data']))
{
echo $this->_create($_POST['data']);
return;
}
// delete an existing paste
elseif (!empty($_GET['deletetoken']) && !empty($_GET['pasteid']))
{
$this->_delete($_GET['pasteid'], $_GET['deletetoken']);
}
// display an existing paste
elseif (!empty($_SERVER['QUERY_STRING']))
{
$this->_read($_SERVER['QUERY_STRING']);
}
// display ZeroBin frontend
$this->_view();
}
/**
* initialize zerobin
*
* @access private
* @return void
*/
private function _init()
{
foreach (array('cfg', 'lib') as $dir)
{
if (!is_file(PATH . $dir . DIRECTORY_SEPARATOR . '.htaccess')) file_put_contents(
PATH . $dir . DIRECTORY_SEPARATOR . '.htaccess',
'Allow from none' . PHP_EOL .
'Deny from all'. PHP_EOL,
LOCK_EX
);
}
$this->_conf = parse_ini_file(PATH . 'cfg' . DIRECTORY_SEPARATOR . 'conf.ini', true);
foreach (array('main', 'model') as $section) {
if (!array_key_exists($section, $this->_conf)) {
throw new Exception("ZeroBin requires configuration section [$section] to be present in configuration file.", 2);
}
}
$this->_model = $this->_conf['model']['class'];
}
/**
* get the model, create one if needed
*
* @access private
* @return zerobin_abstract
*/
private function _model()
{
// if needed, initialize the model
if(is_string($this->_model)) {
$this->_model = forward_static_call(
array($this->_model, 'getInstance'),
$this->_conf['model_options']
);
}
return $this->_model;
}
/**
* Store new paste or comment
*
* POST contains:
* data (mandatory) = json encoded SJCL encrypted text (containing keys: iv,salt,ct)
*
* All optional data will go to meta information:
* expire (optional) = expiration delay (never,5min,10min,1hour,1day,1week,1month,1year,burn) (default:never)
* opendiscusssion (optional) = is the discussion allowed on this paste ? (0/1) (default:0)
* nickname (optional) = in discussion, encoded SJCL encrypted text nickname of author of comment (containing keys: iv,salt,ct)
* parentid (optional) = in discussion, which comment this comment replies to.
* pasteid (optional) = in discussion, which paste this comment belongs to.
*
* @access private
* @param string $data
* @return string
*/
private function _create($data)
{
header('Content-type: application/json');
$error = false;
// Make sure last paste from the IP address was more than X seconds ago.
trafficlimiter::setLimit($this->_conf['traffic']['limit']);
trafficlimiter::setPath($this->_conf['traffic']['dir']);
if (
!trafficlimiter::canPass($_SERVER['REMOTE_ADDR'])
) return $this->_return_message(
1,
'Please wait ' .
$this->_conf['traffic']['limit'] .
' seconds between each post.'
);
// Make sure content is not too big.
$sizelimit = (int) $this->_getMainConfig('sizelimit', 2097152);
if (
strlen($data) > $sizelimit
) return $this->_return_message(
1,
'Paste is limited to ' .
filter::size_humanreadable($sizelimit) .
' of encrypted data.'
);
// Make sure format is correct.
if (!sjcl::isValid($data)) return $this->_return_message(1, 'Invalid data.');
// Read additional meta-information.
$meta=array();
// Read expiration date
if (!empty($_POST['expire']))
{
$selected_expire = (string) $_POST['expire'];
if (array_key_exists($selected_expire, $this->_conf['expire_options'])) {
$expire = $this->_conf['expire_options'][$selected_expire];
} else {
$expire = $this->_conf['expire_options'][$this->_conf['expire']['default']];
}
if ($expire > 0) $meta['expire_date'] = time() + $expire;
}
// Destroy the paste when it is read.
if (!empty($_POST['burnafterreading']))
{
$burnafterreading = $_POST['burnafterreading'];
if ($burnafterreading !== '0')
{
if ($burnafterreading !== '1') $error = true;
$meta['burnafterreading'] = true;
}
}
// Read open discussion flag.
if ($this->_conf['main']['opendiscussion'] && !empty($_POST['opendiscussion']))
{
$opendiscussion = $_POST['opendiscussion'];
if ($opendiscussion !== '0')
{
if ($opendiscussion !== '1') $error = true;
$meta['opendiscussion'] = true;
}
}
// You can't have an open discussion on a "Burn after reading" paste:
if (isset($meta['burnafterreading'])) unset($meta['opendiscussion']);
// Optional nickname for comments
if (!empty($_POST['nickname']))
{
// Generation of the anonymous avatar (Vizhash):
// If a nickname is provided, we generate a Vizhash.
// (We assume that if the user did not enter a nickname, he/she wants
// to be anonymous and we will not generate the vizhash.)
$nick = $_POST['nickname'];
if (!sjcl::isValid($nick))
{
$error = true;
}
else
{
$meta['nickname'] = $nick;
$vz = new vizhash16x16();
$pngdata = $vz->generate($_SERVER['REMOTE_ADDR']);
if ($pngdata != '')
{
$meta['vizhash'] = 'data:image/png;base64,' . base64_encode($pngdata);
}
// Once the avatar is generated, we do not keep the IP address, nor its hash.
}
}
if ($error) return $this->_return_message(1, 'Invalid data.');
// Add post date to meta.
$meta['postdate'] = time();
// We just want a small hash to avoid collisions:
// Half-MD5 (64 bits) will do the trick
$dataid = substr(hash('md5', $data), 0, 16);
$storage = array('data' => $data);
// Add meta-information only if necessary.
if (count($meta)) $storage['meta'] = $meta;
// The user posts a comment.
if (
!empty($_POST['parentid']) &&
!empty($_POST['pasteid'])
)
{
$pasteid = (string) $_POST['pasteid'];
$parentid = (string) $_POST['parentid'];
if (
!filter::is_valid_paste_id($pasteid) ||
!filter::is_valid_paste_id($parentid)
) return $this->_return_message(1, 'Invalid data.');
// Comments do not expire (it's the paste that expires)
unset($storage['expire_date']);
unset($storage['opendiscussion']);
// Make sure paste exists.
if (
!$this->_model()->exists($pasteid)
) return $this->_return_message(1, 'Invalid data.');
// Make sure the discussion is opened in this paste.
$paste = $this->_model()->read($pasteid);
if (
!$paste->meta->opendiscussion
) return $this->_return_message(1, 'Invalid data.');
// Check for improbable collision.
if (
$this->_model()->existsComment($pasteid, $parentid, $dataid)
) return $this->_return_message(1, 'You are unlucky. Try again.');
// New comment
if (
$this->_model()->createComment($pasteid, $parentid, $dataid, $storage) === false
) return $this->_return_message(1, 'Error saving comment. Sorry.');
// 0 = no error
return $this->_return_message(0, $dataid);
}
// The user posts a standard paste.
else
{
// Check for improbable collision.
if (
$this->_model()->exists($dataid)
) return $this->_return_message(1, 'You are unlucky. Try again.');
// New paste
if (
$this->_model()->create($dataid, $storage) === false
) return $this->_return_message(1, 'Error saving paste. Sorry.');
// Generate the "delete" token.
// The token is the hmac of the pasteid signed with the server salt.
// The paste can be delete by calling http://example.com/zerobin/?pasteid=<pasteid>&deletetoken=<deletetoken>
$deletetoken = hash_hmac('sha1', $dataid, serversalt::get());
// 0 = no error
return $this->_return_message(0, $dataid, array('deletetoken' => $deletetoken));
}
return $this->_return_message(1, 'Server error.');
}
/**
* Delete an existing paste
*
* @access private
* @param string $dataid
* @param string $deletetoken
* @return void
*/
private function _delete($dataid, $deletetoken)
{
// Is this a valid paste identifier?
if (!filter::is_valid_paste_id($dataid))
{
$this->_error = 'Invalid paste ID.';
return;
}
// Check that paste exists.
if (!$this->_model()->exists($dataid))
{
$this->_error = 'Paste does not exist, has expired or has been deleted.';
return;
}
// Make sure token is valid.
serversalt::setPath($this->_conf['traffic']['dir']);
if (!filter::slow_equals($deletetoken, hash_hmac('sha1', $dataid, serversalt::get())))
{
$this->_error = 'Wrong deletion token. Paste was not deleted.';
return;
}
// Paste exists and deletion token is valid: Delete the paste.
$this->_model()->delete($dataid);
$this->_status = 'Paste was properly deleted.';
}
/**
* Read an existing paste or comment
*
* @access private
* @param string $dataid
* @return void
*/
private function _read($dataid)
{
// Is this a valid paste identifier?
if (!filter::is_valid_paste_id($dataid))
{
$this->_error = 'Invalid paste ID.';
return;
}
// show the same error message if the paste expired or does not exist
$genericError = 'Paste does not exist, has expired or has been deleted.';
// Check that paste exists.
if ($this->_model()->exists($dataid))
{
// Get the paste itself.
$paste = $this->_model()->read($dataid);
// See if paste has expired.
if (
isset($paste->meta->expire_date) &&
$paste->meta->expire_date < time()
)
{
// Delete the paste
$this->_model()->delete($dataid);
$this->_error = $genericError;
}
// If no error, return the paste.
else
{
// We kindly provide the remaining time before expiration (in seconds)
if (
property_exists($paste->meta, 'expire_date')
) $paste->meta->remaining_time = $paste->meta->expire_date - time();
// The paste itself is the first in the list of encrypted messages.
$messages = array($paste);
// If it's a discussion, get all comments.
if (
property_exists($paste->meta, 'opendiscussion') &&
$paste->meta->opendiscussion
)
{
$messages = array_merge(
$messages,
$this->_model()->readComments($dataid)
);
}
$this->_data = json_encode($messages);
// If the paste was meant to be read only once, delete it.
if (
property_exists($paste->meta, 'burnafterreading') &&
$paste->meta->burnafterreading
) $this->_model()->delete($dataid);
}
}
else
{
$this->_error = $genericError;
}
}
/**
* Display ZeroBin frontend.
*
* @access private
* @return void
*/
private function _view()
{
// set headers to disable caching
$time = gmdate('D, d M Y H:i:s \G\M\T');
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Pragma: no-cache');
header('Expires: ' . $time);
header('Last-Modified: ' . $time);
header('Vary: Accept');
// label all the expiration options
$expire = array();
foreach ($this->_conf['expire_options'] as $key => $value) {
$expire[$key] = array_key_exists($key, $this->_conf['expire_labels']) ?
$this->_conf['expire_labels'][$key] :
$key;
}
$page = new RainTPL;
$page::$path_replace = false;
// we escape it here because ENT_NOQUOTES can't be used in RainTPL templates
$page->assign('CIPHERDATA', htmlspecialchars($this->_data, ENT_NOQUOTES));
$page->assign('ERROR', $this->_error);
$page->assign('STATUS', $this->_status);
$page->assign('VERSION', self::VERSION);
$page->assign('OPENDISCUSSION', $this->_getMainConfig('opendiscussion', true));
$page->assign('SYNTAXHIGHLIGHTING', $this->_getMainConfig('syntaxhighlighting', true));
$page->assign('SYNTAXHIGHLIGHTINGTHEME', $this->_getMainConfig('syntaxhighlightingtheme', ''));
$page->assign('NOTICE', $this->_getMainConfig('notice', ''));
$page->assign('BURNAFTERREADINGSELECTED', $this->_getMainConfig('burnafterreadingselected', false));
$page->assign('BASE64JSVERSION', $this->_getMainConfig('base64version', '2.1.9'));
$page->assign('EXPIRE', $expire);
$page->assign('EXPIREDEFAULT', $this->_conf['expire']['default']);
$page->draw($this->_getMainConfig('template', 'page'));
}
/**
* get configuration option from [main] section, optionally set a default
*
* @access private
* @param string $option
* @param mixed $default (optional)
* @return mixed
*/
private function _getMainConfig($option, $default = false)
{
return array_key_exists($option, $this->_conf['main']) ?
$this->_conf['main'][$option] :
$default;
}
/**
* return JSON encoded message and exit
*
* @access private
* @param bool $status
* @param string $message
* @param array $other
* @return string
*/
private function _return_message($status, $message, $other = array())
{
$result = array('status' => $status);
if ($status)
{
$result['message'] = $message;
}
else
{
$result['id'] = $message;
}
$result += $other;
return json_encode($result);
}
}