CacheHandler.php

Go to the documentation of this file.

<?php

namespace Elgg\Application;

use Elgg\Application;
use Elgg\Config;
use Elgg\Http\Request;
use Symfony\Component\HttpFoundation\BinaryFileResponse;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;

class CacheHandler {
    
    public static $extensions = [
        'bmp' => "image/bmp",
        'css' => "text/css",
        'gif' => "image/gif",
        'html' => "text/html",
        'ico' => "image/x-icon",
        'jpeg' => "image/jpeg",
        'jpg' => "image/jpeg",
        'js' => "application/javascript",
        'json' => "application/json",
        'png' => "image/png",
        'svg' => "image/svg+xml",
        'swf' => "application/x-shockwave-flash",
        'tiff' => "image/tiff",
        'webp' => "image/webp",
        'xml' => "text/xml",
        'eot' => "application/vnd.ms-fontobject",
        'ttf' => "application/font-ttf",
        'woff' => "application/font-woff",
        'woff2' => "application/font-woff2",
        'otf' => "application/font-otf",
    ];

    public static $utf8_content_types = [
        "text/css",
        "text/html",
        "application/javascript",
        "application/json",
        "image/svg+xml",
        "text/xml",
    ];

    private $config;

    private $request;
    
    protected $simplecache_enabled;

    public function __construct(Config $config, Request $request, $simplecache_enabled) {
        $this->config = $config;
        $this->request = $request;
        $this->simplecache_enabled = $simplecache_enabled;
    }

    public function handleRequest(Request $request, Application $app) {
        $config = $this->config;

        $parsed = $this->parsePath($request->getElggPath());
        if (!$parsed) {
            return $this->send403();
        }
        
        $ts = $parsed['ts'];
        $view = $parsed['view'];
        $viewtype = $parsed['viewtype'];

        $content_type = $this->getContentType($view);
        if (empty($content_type)) {
            return $this->send403("Asset must have a valid file extension");
        }

        $response = Response::create();
        if (in_array($content_type, self::$utf8_content_types)) {
            $response->headers->set('Content-Type', "$content_type;charset=utf-8", true);
        } else {
            $response->headers->set('Content-Type', $content_type, true);
        }

        if (!$this->simplecache_enabled) {
            $app->bootCore();
            if (!headers_sent()) {
                header_remove('Cache-Control');
                header_remove('Pragma');
                header_remove('Expires');
            }
            
            if (!$this->isCacheableView($view)) {
                return $this->send403("Requested view ({$view}) is not an asset");
            }

            $content = $this->getProcessedView($view, $viewtype);
            if ($content === false) {
                return $this->send403();
            }

            $etag = '"' . md5($content) . '"';
            $this->setRevalidateHeaders($etag, $response);
            if ($this->is304($etag)) {
                return Response::create()->setNotModified();
            }

            return $response->setContent($content);
        }

        $etag = "\"$ts\"";
        if ($this->is304($etag)) {
            return Response::create()->setNotModified();
        }

        // trust the client but check for an existing cache file
        $filename = $config->assetroot . "$ts/$viewtype/$view";
        if (file_exists($filename)) {
            $this->sendCacheHeaders($etag, $response);
            return BinaryFileResponse::create($filename, 200, $response->headers->all());
        }

        // the hard way
        $app->bootCore();
        header_remove('Cache-Control');
        header_remove('Pragma');
        header_remove('Expires');

        elgg_set_viewtype($viewtype);
        if (!$this->isCacheableView($view)) {
            return $this->send403("Requested view is not an asset");
        }

        $lastcache = (int) $config->lastcache;

        $filename = $config->assetroot . "$lastcache/$viewtype/$view";

        if ($lastcache == $ts) {
            $this->sendCacheHeaders($etag, $response);

            $content = $this->getProcessedView($view, $viewtype);

            $dir_name = dirname($filename);
            if (!is_dir($dir_name)) {
                // PHP and the server accessing the cache symlink may be a different user. And here
                // it's safe to make everything readable anyway.
                mkdir($dir_name, 0775, true);
            }

            file_put_contents($filename, $content);
            chmod($filename, 0664);
        } else {
            // if wrong timestamp, don't send HTTP cache
            $content = $this->getProcessedView($view, $viewtype);
        }

        return $response->setContent($content);
    }

    public function parsePath($path) {
        // no '..'
        if (false !== strpos($path, '..')) {
            return [];
        }
        // only alphanumeric characters plus /, ., -, and _
        if (preg_match('#[^a-zA-Z0-9/\.\-_]#', $path)) {
            return [];
        }

        // testing showed regex to be marginally faster than array / string functions over 100000 reps
        // it won't make a difference in real life and regex is easier to read.
        // <ts>/<viewtype>/<name/of/view.and.dots>.<type>
        if (!preg_match('#^/cache/([0-9]+)/([^/]+)/(.+)$#', $path, $matches)) {
            return [];
        }

        return [
            'ts' => $matches[1],
            'viewtype' => $matches[2],
            'view' => $matches[3],
        ];
    }

    protected function isCacheableView($view) {
        if (preg_match('~^languages/(.*)\.js$~', $view, $m)) {
            return in_array($m[1],  _elgg_services()->localeService->getLanguageCodes());
        }
        return _elgg_services()->views->isCacheableView($view);
    }

    protected function sendCacheHeaders($etag, Response $response) {
        $response->setSharedMaxAge(86400 * 30 * 6);
        $response->setMaxAge(86400 * 30 * 6);
        $response->headers->set('ETag', $etag);
    }

    protected function setRevalidateHeaders($etag, Response $response) {
        $response->headers->set('Cache-Control', "public, max-age=0, must-revalidate", true);
        $response->headers->set('ETag', $etag);
    }

    protected function is304($etag) {
        $if_none_match = $this->request->headers->get('If-None-Match');
        if ($if_none_match === null) {
            return false;
        }

        // strip -gzip and leading /W
        $if_none_match = trim($if_none_match);
        if (0 === strpos($if_none_match, 'W/')) {
            $if_none_match = substr($if_none_match, 2);
        }
        $if_none_match = str_replace('-gzip', '', $if_none_match);

        return ($if_none_match === $etag);
    }

    public function getContentType($view) {
        $extension = $this->getViewFileType($view);
        
        if (isset(self::$extensions[$extension])) {
            return self::$extensions[$extension];
        } else {
            return null;
        }
    }
    
    public function getViewFileType($view) {
        $extension = (new \SplFileInfo($view))->getExtension();
        $hasValidExtension = isset(self::$extensions[$extension]);

        if ($hasValidExtension) {
            return $extension;
        }
        
        if (preg_match('~(?:^|/)(css|js)(?:$|/)~', $view, $m)) {
            return $m[1];
        }
        
        return 'unknown';
    }

    protected function getProcessedView($view, $viewtype) {
        $content = $this->renderView($view, $viewtype);
        if ($content === false) {
            return false;
        }

        if ($this->simplecache_enabled) {
            $hook_name = 'simplecache:generate';
        } else {
            $hook_name = 'cache:generate';
        }
        $hook_type = $this->getViewFileType($view);
        $hook_params = [
            'view' => $view,
            'viewtype' => $viewtype,
            'view_content' => $content,
        ];
        return \_elgg_services()->hooks->trigger($hook_name, $hook_type, $hook_params, $content);
    }

    protected function renderView($view, $viewtype) {
        elgg_set_viewtype($viewtype);

        if ($viewtype === 'default' && preg_match("#^languages/(.*?)\\.js$#", $view, $matches)) {
            $view = "languages.js";
            $vars = ['language' => $matches[1]];
        } else {
            $vars = [];
        }

        if (!elgg_view_exists($view)) {
            return false;
        }

        // disable error reporting so we don't cache problems
        $this->config->debug = null;

        return elgg_view($view, $vars);
    }

    protected function send403($msg = 'Cache error: bad request') {
        return Response::create($msg, 403);
    }
}