gnu-social/lib/linkheader.php

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<?php
/**
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* StatusNet - the distributed open-source microblogging tool
* Copyright (C) 2010, StatusNet, Inc.
*
* Parse HTTP response for interesting Link: headers
*
* PHP version 5
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* @category Discovery
* @package StatusNet
* @author James Walker <james@status.net>
* @copyright 2010 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
* @link http://status.net/
*/
if (!defined('STATUSNET')) {
exit(1);
}
/**
* Class to represent Link: headers in an HTTP response
*
* Since these are a fairly important part of Hammer-stack discovery, they're
* reified and implemented here.
*
* @category Discovery
* @package StatusNet
* @author James Walker <james@status.net>
* @copyright 2010 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
* @link http://status.net/
*
* @see Discovery
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*/
class LinkHeader
{
var $href;
var $rel;
var $type;
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/**
* Initialize from a string
*
* @param string $str Link: header value
*
* @return LinkHeader self
*/
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function __construct($str)
{
preg_match('/^<[^>]+>/', $str, $uri_reference);
//if (empty($uri_reference)) return;
$this->href = trim($uri_reference[0], '<>');
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$this->rel = array();
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$this->type = null;
// remove uri-reference from header
$str = substr($str, strlen($uri_reference[0]));
// parse link-params
$params = explode(';', $str);
foreach ($params as $param) {
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if (empty($param)) {
continue;
}
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list($param_name, $param_value) = explode('=', $param, 2);
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$param_name = trim($param_name);
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$param_value = preg_replace('(^"|"$)', '', trim($param_value));
// for now we only care about 'rel' and 'type' link params
// TODO do something with the other links-params
switch ($param_name) {
case 'rel':
$this->rel = trim($param_value);
break;
case 'type':
$this->type = trim($param_value);
}
}
}
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/**
* Given an HTTP response, return the requested Link: header
*
* @param HTTP_Request2_Response $response response to check
* @param string $rel relationship to look for
* @param string $type media type to look for
*
* @return LinkHeader discovered header, or null on failure
*/
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static function getLink($response, $rel=null, $type=null)
{
$headers = $response->getHeader('Link');
if ($headers) {
// Can get an array or string, so try to simplify the path
if (!is_array($headers)) {
$headers = array($headers);
}
foreach ($headers as $header) {
$lh = new LinkHeader($header);
if ((is_null($rel) || $lh->rel == $rel) &&
(is_null($type) || $lh->type == $type)) {
return $lh->href;
}
}
}
return null;
}
}