Viewing file:  ContentRewriter.php (6.28 KB) -rwxr-xr-x
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
<?php
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/**
* Implements the Content-Rewrite feature which rewrites all image, css and script
* links to their proxied versions, which can be quite a latency improvement, and
* save the gadget dev's server from melting down
*
*/
class ContentRewriter extends DomRewriter {
private $rewrite;
private $baseUrl;
private $defaultRewrite = array('include-url' => array('*'), 'exclude-url' => array(), 'refresh' => '86400');
public function __construct(GadgetContext $context, Gadget &$gadget) {
parent::__construct($context, $gadget);
// if no rewrite params are set in the gadget but rewrite_by_default is on, use our default rules (rewrite all)
if (! isset($gadget->gadgetSpec->rewrite) && Config::get('rewrite_by_default')) {
$this->rewrite = $this->defaultRewrite;
} else {
$this->rewrite = $gadget->gadgetSpec->rewrite;
}
// the base url of the gadget is used for relative paths
$this->baseUrl = substr($this->context->getUrl(), 0, strrpos($this->context->getUrl(), '/') + 1);
}
/**
* Register our dom node observers
*
* @param GadgetRewriter $gadgetRewriter
*/
public function register(GadgetRewriter &$gadgetRewriter) {
$gadgetRewriter->addObserver('img', $this, 'rewriteImage');
$gadgetRewriter->addObserver('style', $this, 'rewriteStyle');
$gadgetRewriter->addObserver('script', $this, 'rewriteScript');
$gadgetRewriter->addObserver('link', $this, 'rewriteStyleLink');
}
/**
* Produces the proxied version of a URL if it falls within the content-rewrite params and
* will append a refresh param to the proxied url based on the expires param, and the gadget
* url so that the proxy server knows to rewrite it's content or not
*
* @param string $url
*/
private function getProxyUrl($url) {
if (strpos(strtolower($url), 'http://') === false && strpos(strtolower($url), 'https://') === false) {
$url = $this->baseUrl . $url;
}
$url = Config::get('web_prefix') . '/gadgets/proxy?url=' . urlencode($url);
$url .= '&refresh=' . (isset($this->rewrite['expires']) && is_numeric($this->rewrite['expires']) ? $this->rewrite['expires'] : '3600');
$url .= '&gadget=' . urlencode($this->context->getUrl());
return $url;
}
/**
* Checks the URL against the include-url and exclude-url params
*
* @param string $url
*/
private function includedUrl($url) {
$included = $excluded = false;
if (isset($this->rewrite['include-url'])) {
foreach ($this->rewrite['include-url'] as $includeUrl) {
if ($includeUrl == '*' || strpos($url, $includeUrl) !== false) {
$included = true;
break;
}
}
}
if (isset($this->rewrite['exclude-url'])) {
foreach ($this->rewrite['exclude-url'] as $excludeUrl) {
if ($excludeUrl == '*' || strpos($url, $excludeUrl) !== false) {
$excluded = true;
break;
}
}
}
return ($included && ! $excluded);
}
/**
* Rewrites the src attribute of an img tag
*
* @param DOMElement $node
*/
public function rewriteImage(DOMElement &$node) {
if (($src = $node->getAttribute('src')) != null && $this->includedUrl($src)) {
$node->setAttribute('src', $this->getProxyUrl($src));
}
}
/**
* Uses rewriteCSS to find url(<url tag>) constructs and rewrite them to their
* proxied counterparts
*
* @param DOMElement $node
*/
public function rewriteStyle(DOMElement &$node) {
$node->nodeValue = $this->rewriteCSS($node->nodeValue);
}
/**
* Does the actual CSS rewriting, this is a seperate function so it can be called
* from the proxy handler too
*
* @param string $content
* @return string
*/
public function rewriteCSS($content) {
$newVal = '';
// loop through the url elements in the content
while (($pos = strpos($content, 'url')) !== false) {
// output everything before this url tag
$newVal .= substr($content, 0, $pos + 3);
$content = substr($content, $pos + 3);
// low tech protection against miss-reading tags, if the open ( is to far away, this is probabbly a miss-read
if (($beginTag = strpos($content, '(')) < 4) {
$content = substr($content, $beginTag + 1);
$endTag = strpos($content, ')');
$tag = str_replace(array("'", "\""), '', trim(substr($content, 0, $endTag)));
// at this point $tag should be the actual url aka: http://example.org/bar/foo.gif
if ($this->includedUrl($tag)) {
$newVal .= "('" . $this->getProxyUrl($tag) . "')";
} else {
$newVal .= "('$tag')";
}
$content = substr($content, $endTag + 1);
}
}
// append what's left
$newVal .= $content;
return $newVal;
}
/**
* Rewrites <script src="http://example.org/foo.js" /> tags into their proxied versions
*
* @param DOMElement $node
*/
public function rewriteScript(DOMElement &$node) {
if (($src = $node->getAttribute('src')) != null && $this->includedUrl($src)) {
// make sure not to rewrite our forcedJsLibs src tag, else things break
if (strpos($src, '/gadgets/js') === false) {
$node->setAttribute('src', $this->getProxyUrl($src));
}
}
}
/**
* Rewrites <link href="http://example.org/foo.css" /> tags into their proxied versions
*
* @param DOMElement $node
*/
public function rewriteStyleLink(DOMElement &$node) {
if (($src = $node->getAttribute('href')) != null && $this->includedUrl($src)) {
$node->setAttribute('href', $this->getProxyUrl($src));
}
}
}
|