PrivateBin / PrivateBin

lib/Data/Filesystem.php

<?php
/**
 * PrivateBin
 *
 * a zero-knowledge paste bin
 *
 * @link      https://github.com/PrivateBin/PrivateBin
 * @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
 * @license   https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
 */

namespace PrivateBin\Data;

use Exception;
use GlobIterator;
use PrivateBin\Json;

/**
 * Filesystem
 *
 * Model for filesystem data access, implemented as a singleton.
 */
class Filesystem extends AbstractData
{
    /**
     * glob() pattern of the two folder levels and the paste files under the
     * configured path. Needs to return both files with and without .php suffix,
     * so they can be hardened by _prependRename(), which is hooked into exists().
     *
     * > Note that wildcard patterns are not regular expressions, although they
     * > are a bit similar.
     *
     * @link  https://man7.org/linux/man-pages/man7/glob.7.html
     * @const string
     */
    const PASTE_FILE_PATTERN = DIRECTORY_SEPARATOR . '[a-f0-9][a-f0-9]' .
        DIRECTORY_SEPARATOR . '[a-f0-9][a-f0-9]' . DIRECTORY_SEPARATOR .
        '[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]' .
        '[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]*';

    /**
     * first line in paste or comment files, to protect their contents from browsing exposed data directories
     *
     * @const string
     */
    const PROTECTION_LINE = '<?php http_response_code(403); /*';

    /**
     * line in generated .htaccess files, to protect exposed directories from being browsable on apache web servers
     *
     * @const string
     */
    const HTACCESS_LINE = 'Require all denied';

    /**
     * path in which to persist something
     *
     * @access private
     * @var    string
     */
    private $_path = 'data';

    /**
     * instantiates a new Filesystem data backend
     *
     * @access public
     * @param  array $options
     */
    public function __construct(array $options)
    {
        // if given update the data directory
        if (
            is_array($options) &&
            array_key_exists('dir', $options)
        ) {
            $this->_path = $options['dir'];
        }
    }

    /**
     * Create a paste.
     *
     * @access public
     * @param  string $pasteid
     * @param  array  $paste
     * @return bool
     */
    public function create($pasteid, array $paste)
    {
        $storagedir = $this->_dataid2path($pasteid);
        $file       = $storagedir . $pasteid . '.php';
        if (is_file($file)) {
            return false;
        }
        if (!is_dir($storagedir)) {
            mkdir($storagedir, 0700, true);
        }
        return $this->_store($file, $paste);
    }

    /**
     * Read a paste.
     *
     * @access public
     * @param  string $pasteid
     * @return array|false
     */
    public function read($pasteid)
    {
        if (
            !$this->exists($pasteid) ||
            !$paste = $this->_get($this->_dataid2path($pasteid) . $pasteid . '.php')
        ) {
            return false;
        }
        return self::upgradePreV1Format($paste);
    }

    /**
     * Delete a paste and its discussion.
     *
     * @access public
     * @param  string $pasteid
     */
    public function delete($pasteid)
    {
        $pastedir = $this->_dataid2path($pasteid);
        if (is_dir($pastedir)) {
            // Delete the paste itself.
            if (is_file($pastedir . $pasteid . '.php')) {
                unlink($pastedir . $pasteid . '.php');
            }

            // Delete discussion if it exists.
            $discdir = $this->_dataid2discussionpath($pasteid);
            if (is_dir($discdir)) {
                // Delete all files in discussion directory
                $dir = dir($discdir);
                while (false !== ($filename = $dir->read())) {
                    if (is_file($discdir . $filename)) {
                        unlink($discdir . $filename);
                    }
                }
                $dir->close();
                rmdir($discdir);
            }
        }
    }

    /**
     * Test if a paste exists.
     *
     * @access public
     * @param  string $pasteid
     * @return bool
     */
    public function exists($pasteid)
    {
        $basePath  = $this->_dataid2path($pasteid) . $pasteid;
        $pastePath = $basePath . '.php';
        // convert to PHP protected files if needed
        if (is_readable($basePath)) {
            $this->_prependRename($basePath, $pastePath);

            // convert comments, too
            $discdir = $this->_dataid2discussionpath($pasteid);
            if (is_dir($discdir)) {
                $dir = dir($discdir);
                while (false !== ($filename = $dir->read())) {
                    if (substr($filename, -4) !== '.php' && strlen($filename) >= 16) {
                        $commentFilename = $discdir . $filename . '.php';
                        $this->_prependRename($discdir . $filename, $commentFilename);
                    }
                }
                $dir->close();
            }
        }
        return is_readable($pastePath);
    }

    /**
     * Create a comment in a paste.
     *
     * @access public
     * @param  string $pasteid
     * @param  string $parentid
     * @param  string $commentid
     * @param  array  $comment
     * @return bool
     */
    public function createComment($pasteid, $parentid, $commentid, array $comment)
    {
        $storagedir = $this->_dataid2discussionpath($pasteid);
        $file       = $storagedir . $pasteid . '.' . $commentid . '.' . $parentid . '.php';
        if (is_file($file)) {
            return false;
        }
        if (!is_dir($storagedir)) {
            mkdir($storagedir, 0700, true);
        }
        return $this->_store($file, $comment);
    }

    /**
     * Read all comments of paste.
     *
     * @access public
     * @param  string $pasteid
     * @return array
     */
    public function readComments($pasteid)
    {
        $comments = array();
        $discdir  = $this->_dataid2discussionpath($pasteid);
        if (is_dir($discdir)) {
            $dir = dir($discdir);
            while (false !== ($filename = $dir->read())) {
                // Filename is in the form pasteid.commentid.parentid.php:
                // - pasteid is the paste this reply belongs to.
                // - commentid is the comment identifier itself.
                // - parentid is the comment this comment replies to (It can be pasteid)
                if (is_file($discdir . $filename)) {
                    $comment = $this->_get($discdir . $filename);
                    $items   = explode('.', $filename);
                    // Add some meta information not contained in file.
                    $comment['id']       = $items[1];
                    $comment['parentid'] = $items[2];

                    // Store in array
                    $key            = $this->getOpenSlot(
                        $comments,
                        (int) array_key_exists('created', $comment['meta']) ?
                        $comment['meta']['created'] : // v2 comments
                        $comment['meta']['postdate']  // v1 comments
                    );
                    $comments[$key] = $comment;
                }
            }
            $dir->close();

            // Sort comments by date, oldest first.
            ksort($comments);
        }
        return $comments;
    }

    /**
     * Test if a comment exists.
     *
     * @access public
     * @param  string $pasteid
     * @param  string $parentid
     * @param  string $commentid
     * @return bool
     */
    public function existsComment($pasteid, $parentid, $commentid)
    {
        return is_file(
            $this->_dataid2discussionpath($pasteid) .
            $pasteid . '.' . $commentid . '.' . $parentid . '.php'
        );
    }

    /**
     * Save a value.
     *
     * @access public
     * @param  string $value
     * @param  string $namespace
     * @param  string $key
     * @return bool
     */
    public function setValue($value, $namespace, $key = '')
    {
        switch ($namespace) {
            case 'purge_limiter':
                return $this->_storeString(
                    $this->_path . DIRECTORY_SEPARATOR . 'purge_limiter.php',
                    '<?php' . PHP_EOL . '$GLOBALS[\'purge_limiter\'] = ' . $value . ';'
                );
            case 'salt':
                return $this->_storeString(
                    $this->_path . DIRECTORY_SEPARATOR . 'salt.php',
                    '<?php # |' . $value . '|'
                );
            case 'traffic_limiter':
                $this->_last_cache[$key] = $value;
                return $this->_storeString(
                    $this->_path . DIRECTORY_SEPARATOR . 'traffic_limiter.php',
                    '<?php' . PHP_EOL . '$GLOBALS[\'traffic_limiter\'] = ' . var_export($this->_last_cache, true) . ';'
                );
        }
        return false;
    }

    /**
     * Load a value.
     *
     * @access public
     * @param  string $namespace
     * @param  string $key
     * @return string
     */
    public function getValue($namespace, $key = '')
    {
        switch ($namespace) {
            case 'purge_limiter':
                $file = $this->_path . DIRECTORY_SEPARATOR . 'purge_limiter.php';
                if (is_readable($file)) {
                    require $file;
                    return $GLOBALS['purge_limiter'];
                }
                break;
            case 'salt':
                $file = $this->_path . DIRECTORY_SEPARATOR . 'salt.php';
                if (is_readable($file)) {
                    $items = explode('|', file_get_contents($file));
                    if (is_array($items) && count($items) == 3) {
                        return $items[1];
                    }
                }
                break;
            case 'traffic_limiter':
                $file = $this->_path . DIRECTORY_SEPARATOR . 'traffic_limiter.php';
                if (is_readable($file)) {
                    require $file;
                    $this->_last_cache = $GLOBALS['traffic_limiter'];
                    if (array_key_exists($key, $this->_last_cache)) {
                        return $this->_last_cache[$key];
                    }
                }
                break;
        }
        return '';
    }

    /**
     * get the data
     *
     * @access public
     * @param  string $filename
     * @return array|false $data
     */
    private function _get($filename)
    {
        return Json::decode(
            substr(
                file_get_contents($filename),
                strlen(self::PROTECTION_LINE . PHP_EOL)
            )
        );
    }

    /**
     * Returns up to batch size number of paste ids that have expired
     *
     * @access private
     * @param  int $batchsize
     * @return array
     */
    protected function _getExpiredPastes($batchsize)
    {
        $pastes = array();
        $count  = 0;
        $opened = 0;
        $limit  = $batchsize * 10; // try at most 10 times $batchsize pastes before giving up
        $time   = time();
        $files  = $this->getAllPastes();
        shuffle($files);
        foreach ($files as $pasteid) {
            if ($this->exists($pasteid)) {
                $data = $this->read($pasteid);
                if (
                    array_key_exists('expire_date', $data['meta']) &&
                    $data['meta']['expire_date'] < $time
                ) {
                    $pastes[] = $pasteid;
                    if (++$count >= $batchsize) {
                        break;
                    }
                }
                if (++$opened >= $limit) {
                    break;
                }
            }
        }
        return $pastes;
    }

    /**
     * @inheritDoc
     */
    public function getAllPastes()
    {
        $pastes = array();
        foreach (new GlobIterator($this->_path . self::PASTE_FILE_PATTERN) as $file) {
            if ($file->isFile()) {
                $pastes[] = $file->getBasename('.php');
            }
        }
        return $pastes;
    }

    /**
     * Convert paste id to storage path.
     *
     * The idea is to creates subdirectories in order to limit the number of files per directory.
     * (A high number of files in a single directory can slow things down.)
     * eg. "f468483c313401e8" will be stored in "data/f4/68/f468483c313401e8"
     * High-trafic websites may want to deepen the directory structure (like Squid does).
     *
     * eg. input 'e3570978f9e4aa90' --> output 'data/e3/57/'
     *
     * @access private
     * @param  string $dataid
     * @return string
     */
    private function _dataid2path($dataid)
    {
        return $this->_path . DIRECTORY_SEPARATOR .
            substr($dataid, 0, 2) . DIRECTORY_SEPARATOR .
            substr($dataid, 2, 2) . DIRECTORY_SEPARATOR;
    }

    /**
     * Convert paste id to discussion storage path.
     *
     * eg. input 'e3570978f9e4aa90' --> output 'data/e3/57/e3570978f9e4aa90.discussion/'
     *
     * @access private
     * @param  string $dataid
     * @return string
     */
    private function _dataid2discussionpath($dataid)
    {
        return $this->_dataid2path($dataid) . $dataid .
            '.discussion' . DIRECTORY_SEPARATOR;
    }

    /**
     * store the data
     *
     * @access public
     * @param  string $filename
     * @param  array  $data
     * @return bool
     */
    private function _store($filename, array $data)
    {
        try {
            return $this->_storeString(
                $filename,
                self::PROTECTION_LINE . PHP_EOL . Json::encode($data)
            );
        } catch (Exception $e) {
            return false;
        }
    }

    /**
     * store a string
     *
     * @access public
     * @param  string $filename
     * @param  string $data
     * @return bool
     */
    private function _storeString($filename, $data)
    {
        // Create storage directory if it does not exist.
        if (!is_dir($this->_path)) {
            if (!@mkdir($this->_path, 0700)) {
                return false;
            }
        }
        $file = $this->_path . DIRECTORY_SEPARATOR . '.htaccess';
        if (!is_file($file)) {
            $writtenBytes = 0;
            if ($fileCreated = @touch($file)) {
                $writtenBytes = @file_put_contents(
                    $file,
                    self::HTACCESS_LINE . PHP_EOL,
                    LOCK_EX
                );
            }
            if (
                $fileCreated === false ||
                $writtenBytes === false ||
                $writtenBytes < strlen(self::HTACCESS_LINE . PHP_EOL)
            ) {
                return false;
            }
        }

        $fileCreated  = true;
        $writtenBytes = 0;
        if (!is_file($filename)) {
            $fileCreated = @touch($filename);
        }
        if ($fileCreated) {
            $writtenBytes = @file_put_contents($filename, $data, LOCK_EX);
        }
        if ($fileCreated === false || $writtenBytes === false || $writtenBytes < strlen($data)) {
            return false;
        }
        @chmod($filename, 0640); // protect file from access by other users on the host

It seems like you do not handle an error condition for chmod(). This can introduce security issues, and is generally not recommended.

        return true;
    }

    /**
     * rename a file, prepending the protection line at the beginning
     *
     * @access public
     * @param  string $srcFile
     * @param  string $destFile
     * @return void
     */
    private function _prependRename($srcFile, $destFile)
    {
        // don't overwrite already converted file
        if (!is_readable($destFile)) {
            $handle = fopen($srcFile, 'r', false, stream_context_create());
            file_put_contents($destFile, self::PROTECTION_LINE . PHP_EOL);
            file_put_contents($destFile, $handle, FILE_APPEND);
            fclose($handle);
        }
        unlink($srcFile);
    }
}