/**
* This should be called statically and will build a Yadis
* instance if the discovery process succeeds. This implements
* Yadis discovery as specified in the Yadis specification.
*
* @param string $uri The URI on which to perform Yadis discovery.
*
* @param array $http_response An array reference where the HTTP
* response object will be stored (see {@link
* Services_Yadis_HTTPResponse}.
*
* @param Services_Yadis_HTTPFetcher $fetcher An instance of a
* Services_Yadis_HTTPFetcher subclass.
*
* @param array $extra_ns_map An array which maps namespace names
* to namespace URIs to be used when parsing the Yadis XRDS
* document.
*
* @param integer $timeout An optional fetcher timeout, in seconds.
*
* @return mixed $obj Either null or an instance of
* Services_Yadis_Yadis, depending on whether the discovery
* succeeded.
*/
function discover($uri, &$http_response, &$fetcher, $extra_ns_map = null, $timeout = 20)
{
if (!$uri) {
return null;
}
$request_uri = $uri;
$headers = array("Accept: application/xrds+xml");
if (!$fetcher) {
$fetcher = Services_Yadis_Yadis::getHTTPFetcher($timeout);
}
$response = $fetcher->get($uri, $headers);
$http_response = $response;
if (!$response) {
return null;
}
if ($response->status != 200) {
return null;
}
$xrds_uri = $response->final_url;
$uri = $response->final_url;
$body = $response->body;
$xrds_header_uri = Services_Yadis_Yadis::_getHeader($response->headers, array('x-xrds-location', 'x-yadis-location'));
$content_type = Services_Yadis_Yadis::_getHeader($response->headers, array('content-type'));
if ($xrds_header_uri) {
$xrds_uri = $xrds_header_uri;
$response = $fetcher->get($xrds_uri);
$http_response = $response;
if (!$response) {
return null;
} else {
$body = $response->body;
$headers = $response->headers;
$content_type = Services_Yadis_Yadis::_getHeader($headers, array('content-type'));
}
}
if (Services_Yadis_Yadis::_getContentType($content_type) != 'application/xrds+xml') {
// Treat the body as HTML and look for a META tag.
$parser = new Services_Yadis_ParseHTML();
$new_uri = $parser->getHTTPEquiv($body);
$xrds_uri = null;
if ($new_uri) {
$response = $fetcher->get($new_uri);
if ($response->status != 200) {
return null;
}
$http_response = $response;
$body = $response->body;
$xrds_uri = $new_uri;
$content_type = Services_Yadis_Yadis::_getHeader($response->headers, array('content-type'));
}
}
$xrds = Services_Yadis_XRDS::parseXRDS($body, $extra_ns_map);
if ($xrds !== null) {
$y = new Services_Yadis_Yadis();
$y->request_uri = $request_uri;
$y->xrds = $xrds;
$y->uri = $uri;
$y->xrds_uri = $xrds_uri;
$y->body = $body;
$y->content_type = $content_type;
return $y;
} else {
return null;
}
}
