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<?php
namespace phinde;
class HubUrlExtractor
{
/**
* HTTP request object that's used to do the requests
*
* @var \HTTP_Request2
*/
protected $request;
/**
* Get the hub and self/canonical URL of a given topic URL.
* Uses link headers and parses HTML link rels.
*
* @param string $url Topic URL
*
* @return array Array of URLs with keys: hub, self
*/
public function getUrls($url)
{
//at first, try a HEAD request that does not transfer so much data
$req = $this->getRequest();
$req->setUrl($url);
$req->setMethod(\HTTP_Request2::METHOD_HEAD);
$res = $req->send();
if (intval($res->getStatus() / 100) >= 4
&& $res->getStatus() != 405 //method not supported/allowed
) {
return null;
}
$url = $res->getEffectiveUrl();
$base = new \Net_URL2($url);
$urls = $this->extractHeader($res);
if (count($urls) === 2) {
return $this->absolutifyUrls($urls, $base);
}
list($type) = explode(';', $res->getHeader('Content-type'));
if ($type != 'text/html' && $type != 'text/xml'
&& $type != 'application/xhtml+xml'
//FIXME: atom, rss
&& $res->getStatus() != 405//HEAD method not allowed
) {
//we will not be able to extract links from the content
return $urls;
}
//HEAD failed, do a normal GET
$req->setMethod(\HTTP_Request2::METHOD_GET);
$res = $req->send();
if (intval($res->getStatus() / 100) >= 4) {
return $urls;
}
//yes, maybe the server does return this header now
// e.g. PHP's Phar::webPhar() does not work with HEAD
// https://bugs.php.net/bug.php?id=51918
$urls = array_merge($this->extractHeader($res), $urls);
if (count($urls) === 2) {
return $this->absolutifyUrls($urls, $base);
}
//FIXME: atom/rss
$body = $res->getBody();
$doc = $this->loadHtml($body, $res);
$xpath = new \DOMXPath($doc);
$xpath->registerNamespace('h', 'http://www.w3.org/1999/xhtml');
$nodeList = $xpath->query(
'/*[self::html or self::h:html]'
. '/*[self::head or self::h:head]'
. '/*[(self::link or self::h:link)'
. ' and'
. ' ('
. ' contains(concat(" ", normalize-space(@rel), " "), " hub ")'
. ' or'
. ' contains(concat(" ", normalize-space(@rel), " "), " canonical ")'
. ' or'
. ' contains(concat(" ", normalize-space(@rel), " "), " self ")'
. ' )'
. ']'
);
if ($nodeList->length == 0) {
//topic has no links
return $urls;
}
foreach ($nodeList as $link) {
$uri = $link->attributes->getNamedItem('href')->nodeValue;
$types = explode(
' ', $link->attributes->getNamedItem('rel')->nodeValue
);
foreach ($types as $type) {
if ($type == 'canonical') {
$type = 'self';
}
if ($type == 'hub' || $type == 'self'
&& !isset($urls[$type])
) {
$urls[$type] = $uri;
}
}
}
//FIXME: base href
return $this->absolutifyUrls($urls, $base);
}
/**
* Extract hub url from the HTTP response headers.
*
* @param object $res HTTP response
*
* @return array Array with maximal two keys: hub and self
*/
protected function extractHeader(\HTTP_Request2_Response $res)
{
$http = new \HTTP2();
$urls = array();
$links = $http->parseLinks($res->getHeader('Link'));
foreach ($links as $link) {
if (isset($link['_uri']) && isset($link['rel'])) {
if (!isset($urls['hub'])
&& array_search('hub', $link['rel']) !== false
) {
$urls['hub'] = $link['_uri'];
}
if (!isset($urls['self'])
&& array_search('self', $link['rel']) !== false
) {
$urls['self'] = $link['_uri'];
}
}
}
return $urls;
}
/**
* Load a DOMDocument from the given HTML or XML
*
* @param string $sourceBody Content of $source URI
* @param object $res HTTP response from fetching $source
*
* @return \DOMDocument DOM document object with HTML/XML loaded
*/
protected static function loadHtml($sourceBody, \HTTP_Request2_Response $res)
{
$doc = new \DOMDocument();
libxml_clear_errors();
$old = libxml_use_internal_errors(true);
$typeParts = explode(';', $res->getHeader('content-type'));
$type = $typeParts[0];
if ($type == 'application/xhtml+xml'
|| $type == 'application/xml'
|| $type == 'text/xml'
) {
$doc->loadXML($sourceBody);
} else {
$doc->loadHTML($sourceBody);
}
libxml_clear_errors();
libxml_use_internal_errors($old);
return $doc;
}
/**
* Returns the HTTP request object clone that can be used
* for one HTTP request.
*
* @return HTTP_Request2 Clone of the setRequest() object
*/
public function getRequest()
{
if ($this->request === null) {
$request = new \HTTP_Request2();
$request->setConfig('follow_redirects', true);
$this->setRequestTemplate($request);
}
//we need to clone because previous requests could have
//set internal variables like POST data that we don't want now
return clone $this->request;
}
/**
* Sets a custom HTTP request object that will be used to do HTTP requests
*
* @param object $request Request object
*
* @return self
*/
public function setRequestTemplate(\HTTP_Request2 $request)
{
$this->request = $request;
return $this;
}
/**
* Make the list of urls absolute
*
* @param array $urls Array of maybe relative URLs
* @param object $base Base URL to resolve the relatives against
*
* @return array List of absolute URLs
*/
protected function absolutifyUrls($urls, \Net_URL2 $base)
{
foreach ($urls as $key => $url) {
$urls[$key] = (string) $base->resolve($url);
}
return $urls;
}
}
?>
|
