privatebin-mirror/lib/Request.php

<?php declare(strict_types=1);
/**
 * 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;

use JsonException;
use PrivateBin\Model\Paste;

/**
 * Request
 *
 * parses request parameters and provides helper functions for routing
 */
class Request
{
    /**
     * MIME type for JSON
     *
     * @const string
     */
    const MIME_JSON = 'application/json';

    /**
     * MIME type for HTML
     *
     * @const string
     */
    const MIME_HTML = 'text/html';

    /**
     * MIME type for XHTML
     *
     * @const string
     */
    const MIME_XHTML = 'application/xhtml+xml';

    /**
     * Input stream to use for PUT parameter parsing
     *
     * @access private
     * @var string
     */
    private static $_inputStream = 'php://input';

    /**
     * Operation to perform
     *
     * @access private
     * @var string
     */
    private $_operation = 'view';

    /**
     * Request parameters
     *
     * @access private
     * @var array
     */
    private $_params = [];

    /**
     * If we are in a JSON API context
     *
     * @access private
     * @var bool
     */
    private $_isJsonApi = false;

    /**
     * Return the paste ID of the current document.
     *
     * @access private
     * @return string
     */
    private function getPasteId()
    {
        foreach ($_GET as $key => $value) {
            // only return if value is empty and key is 16 hex chars
            $key = (string) $key;
            if (empty($value) && Paste::isValidId($key)) {
                return $key;
            }
        }

        return 'invalid id';
    }

    /**
     * Constructor
     *
     * @access public
     */
    public function __construct()
    {
        // decide if we are in JSON API or HTML context
        $this->_isJsonApi = $this->_detectJsonRequest();

        // parse parameters, depending on request type
        switch ($_SERVER['REQUEST_METHOD'] ?? 'GET') {
            case 'DELETE':
            case 'PUT':
            case 'POST':
                // it might be a creation or a deletion, the latter is detected below
                $this->_operation = 'create';
                try {
                    $data          = file_get_contents(self::$_inputStream);
                    $this->_params = Json::decode($data);
                    // a valid JSON scalar (number, bool or string) decodes
                    // without error, but is not a usable set of parameters
                    if (!is_array($this->_params)) {
                        $this->_params = [];
                    }
                } catch (JsonException $e) {
                    // ignore error, $this->_params will remain empty
                }
                break;
            default:
                $this->_params = filter_var_array($_GET, [
                    'deletetoken'      => FILTER_SANITIZE_SPECIAL_CHARS,
                    'jsonld'           => FILTER_SANITIZE_SPECIAL_CHARS,
                    'link'             => FILTER_SANITIZE_URL,
                    'pasteid'          => FILTER_SANITIZE_SPECIAL_CHARS,
                    'shortenviayourls' => FILTER_SANITIZE_SPECIAL_CHARS,
                    'shortenviashlink' => FILTER_SANITIZE_SPECIAL_CHARS,
                ], false);
        }
        if (
            !array_key_exists('pasteid', $this->_params) &&
            !array_key_exists('jsonld', $this->_params) &&
            !array_key_exists('link', $this->_params) &&
            array_key_exists('QUERY_STRING', $_SERVER) &&
            !empty($_SERVER['QUERY_STRING'])
        ) {
            $this->_params['pasteid'] = $this->getPasteId();
        }

        // prepare operation, depending on current parameters
        if (
            array_key_exists('pasteid', $this->_params) &&
            is_string($this->_params['pasteid']) &&
            !empty($this->_params['pasteid'])
        ) {
            if (
                array_key_exists('deletetoken', $this->_params) &&
                is_string($this->_params['deletetoken']) &&
                !empty($this->_params['deletetoken'])
            ) {
                $this->_operation = 'delete';
            } elseif ($this->_operation !== 'create') {
                $this->_operation = 'read';
            }
        } elseif (
            array_key_exists('jsonld', $this->_params) &&
            is_string($this->_params['jsonld']) &&
            !empty($this->_params['jsonld'])
        ) {
            $this->_operation = 'jsonld';
        } elseif (
            array_key_exists('link', $this->_params) &&
            is_string($this->_params['link']) &&
            !empty($this->_params['link'])
        ) {
            if (str_contains($this->getRequestUri(), '/shortenviayourls') || array_key_exists('shortenviayourls', $this->_params)) {
                $this->_operation = 'yourlsproxy';
            }
            if (str_contains($this->getRequestUri(), '/shortenviashlink') || array_key_exists('shortenviashlink', $this->_params)) {
                $this->_operation = 'shlinkproxy';
            }
        }
    }

    /**
     * Get current operation
     *
     * @access public
     * @return string
     */
    public function getOperation()
    {
        return $this->_operation;
    }

    /**
     * Get data of paste or comment
     *
     * @access public
     * @return array
     */
    public function getData()
    {
        $data = [
            'adata' => $this->getParam('adata'),
        ];
        $required_keys = ['v', 'ct'];
        $meta          = $this->getParam('meta');
        if (empty($meta)) {
            $required_keys[] = 'pasteid';
            $required_keys[] = 'parentid';
        } else {
            $data['meta'] = $meta;
        }
        foreach ($required_keys as $key) {
            $data[$key] = $this->getParam($key, $key === 'v' ? 1 : '');
        }
        return $data;
    }

    /**
     * Get a request parameter
     *
     * @access public
     * @param  string $param
     * @param  string $default
     * @return string
     */
    public function getParam($param, $default = '')
    {
        return $this->_params[$param] ?? $default;
    }

    /**
     * Get host as requested by the client
     *
     * @access public
     * @return string
     */
    public function getHost()
    {
        $host = array_key_exists('HTTP_HOST', $_SERVER) ? filter_var($_SERVER['HTTP_HOST'], FILTER_SANITIZE_URL) : '';
        return empty($host) ? 'localhost' : $host;
    }

    /**
     * Get request URI path without GET parameters
     *
     * @access public
     * @return string
     */
    public function getRequestUri()
    {
        $uri = array_key_exists('REQUEST_URI', $_SERVER) ? filter_var($_SERVER['REQUEST_URI'], FILTER_SANITIZE_URL) : '';
        return empty($uri) ? '/' : parse_url($uri, PHP_URL_PATH);
    }

    /**
     * If we are in a JSON API context
     *
     * @access public
     * @return bool
     */
    public function isJsonApiCall()
    {
        return $this->_isJsonApi;
    }

    /**
     * Override the default input stream source, used for unit testing
     *
     * @param string $input
     */
    public static function setInputStream($input)
    {
        self::$_inputStream = $input;
    }

    /**
     * Detect the clients supported media type and decide if its a JSON API call or not
     *
     * Adapted from: https://stackoverflow.com/questions/3770513/detect-browser-language-in-php#3771447
     *
     * @access private
     * @return bool
     */
    private function _detectJsonRequest()
    {
        $acceptHeader = $_SERVER['HTTP_ACCEPT'] ?? '';

        // simple cases
        if (
            ($_SERVER['HTTP_X_REQUESTED_WITH'] ?? '') === 'JSONHttpRequest' ||
            (
                str_contains($acceptHeader, self::MIME_JSON) &&
                !str_contains($acceptHeader, self::MIME_HTML) &&
                !str_contains($acceptHeader, self::MIME_XHTML)
            )
        ) {
            return true;
        }

        // advanced case: media type negotiation
        if (!empty($acceptHeader)) {
            $mediaTypes = [];
            foreach (explode(',', trim($acceptHeader)) as $mediaTypeRange) {
                if (preg_match(
                    '#(\*/\*|[a-z\-]+/[a-z\-+*]+(?:\s*;\s*[^q]\S*)*)(?:\s*;\s*q\s*=\s*(0(?:\.\d{0,3})|1(?:\.0{0,3})))?#',
                    trim($mediaTypeRange), $match
                )) {
                    if (!isset($match[2])) {
                        $match[2] = '1.0';
                    } else {
                        $match[2] = (string) floatval($match[2]);
                        if ($match[2] === '0.0') {
                            continue;
                        }
                    }
                    if (!isset($mediaTypes[$match[2]])) {
                        $mediaTypes[$match[2]] = [];
                    }
                    $mediaTypes[$match[2]][] = strtolower($match[1]);
                }
            }
            krsort($mediaTypes);
            foreach ($mediaTypes as $acceptedQuality => $acceptedValues) {
                foreach ($acceptedValues as $acceptedValue) {
                    if (
                        str_starts_with($acceptedValue, self::MIME_HTML) ||
                        str_starts_with($acceptedValue, self::MIME_XHTML)
                    ) {
                        return false;
                    } elseif (str_starts_with($acceptedValue, self::MIME_JSON)) {
                        return true;
                    }
                }
            }
        }
        return false;
    }
}