gnu-social/lib/discovery.php

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<?php
/**
* StatusNet - the distributed open-source microblogging tool
* Copyright (C) 2010, StatusNet, Inc.
*
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* Use Hammer discovery stack to find out interesting things about an URI
*
* 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/>.
*
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* @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/
*/
/**
* This class implements LRDD-based service discovery based on the "Hammer Draft"
* (including webfinger)
*
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* @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 http://groups.google.com/group/webfinger/browse_thread/thread/9f3d93a479e91bbf
*/
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class Discovery
{
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const LRDD_REL = 'lrdd';
const PROFILEPAGE = 'http://webfinger.net/rel/profile-page';
const UPDATESFROM = 'http://schemas.google.com/g/2010#updates-from';
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const HCARD = 'http://microformats.org/profile/hcard';
public $methods = array();
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/**
* Constructor for a discovery object
*
* Registers different discovery methods.
*
* @return Discovery this
*/
public function __construct()
{
$this->registerMethod('Discovery_LRDD_Host_Meta');
$this->registerMethod('Discovery_LRDD_Link_Header');
$this->registerMethod('Discovery_LRDD_Link_HTML');
}
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/**
* Register a discovery class
*
* @param string $class Class name
*
* @return void
*/
public function registerMethod($class)
{
$this->methods[] = $class;
}
/**
* Given a "user id" make sure it's normalized to either a webfinger
* acct: uri or a profile HTTP URL.
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*
* @param string $user_id User ID to normalize
*
* @return string normalized acct: or http(s)?: URI
*/
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public static function normalize($user_id)
{
if (substr($user_id, 0, 5) == 'http:' ||
substr($user_id, 0, 6) == 'https:' ||
substr($user_id, 0, 5) == 'acct:') {
return $user_id;
}
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if (strpos($user_id, '@') !== false) {
return 'acct:' . $user_id;
}
return 'http://' . $user_id;
}
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/**
* Determine if a string is a Webfinger ID
*
* Webfinger IDs look like foo@example.com or acct:foo@example.com
*
* @param string $user_id ID to check
*
* @return boolean true if $user_id is a Webfinger, else false
*/
public static function isWebfinger($user_id)
{
$uri = Discovery::normalize($user_id);
return (substr($uri, 0, 5) == 'acct:');
}
/**
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* Given a user ID, return the first available XRD
*
* @param string $id User ID URI
*
* @return XRD XRD object for the user
*/
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public function lookup($id)
{
// Normalize the incoming $id to make sure we have a uri
$uri = $this->normalize($id);
foreach ($this->methods as $class) {
$links = call_user_func(array($class, 'discover'), $uri);
if ($link = Discovery::getService($links, Discovery::LRDD_REL)) {
// Load the LRDD XRD
if (!empty($link['template'])) {
$xrd_uri = Discovery::applyTemplate($link['template'], $uri);
} else {
$xrd_uri = $link['href'];
}
$xrd = $this->fetchXrd($xrd_uri);
if ($xrd) {
return $xrd;
}
}
}
// TRANS: Exception.
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throw new Exception(sprintf(_('Unable to find services for %s.'), $id));
}
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/**
* Given an array of links, returns the matching service
*
* @param array $links Links to check
* @param string $service Service to find
*
* @return array $link assoc array representing the link
*/
public static function getService($links, $service)
{
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if (!is_array($links)) {
return false;
}
foreach ($links as $link) {
if ($link['rel'] == $service) {
return $link;
}
}
}
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/**
* Apply a template using an ID
*
* Replaces {uri} in template string with the ID given.
*
* @param string $template Template to match
* @param string $id User ID to replace with
*
* @return string replaced values
*/
public static function applyTemplate($template, $id)
{
$template = str_replace('{uri}', urlencode($id), $template);
return $template;
}
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/**
* Fetch an XRD file and parse
*
* @param string $url URL of the XRD
*
* @return XRD object representing the XRD file
*/
public static function fetchXrd($url)
{
try {
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$client = new HTTPClient();
$response = $client->get($url);
} catch (HTTP_Request2_Exception $e) {
return false;
}
if ($response->getStatus() != 200) {
return false;
}
return XRD::parse($response->getBody());
}
}
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/**
* Abstract interface for discovery
*
* Objects that implement this interface can retrieve an array of
* XRD links for the URI.
*
* @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/
*/
interface Discovery_LRDD
{
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/**
* Discover interesting info about the URI
*
* @param string $uri URI to inquire about
*
* @return array Links in the XRD file
*/
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public function discover($uri);
}
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/**
* Implementation of discovery using host-meta file
*
* Discovers XRD file for a user by going to the organization's
* host-meta file and trying to find a template for LRDD.
*
* @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/
*/
class Discovery_LRDD_Host_Meta implements Discovery_LRDD
{
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/**
* Discovery core method
*
* For Webfinger and HTTP URIs, fetch the host-meta file
* and look for LRDD templates
*
* @param string $uri URI to inquire about
*
* @return array Links in the XRD file
*/
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public function discover($uri)
{
if (Discovery::isWebfinger($uri)) {
// We have a webfinger acct: - start with host-meta
list($name, $domain) = explode('@', $uri);
} else {
$domain = parse_url($uri, PHP_URL_HOST);
}
$url = 'http://'. $domain .'/.well-known/host-meta';
$xrd = Discovery::fetchXrd($url);
if ($xrd) {
if ($xrd->host != $domain) {
return false;
}
return $xrd->links;
}
}
}
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/**
* Implementation of discovery using HTTP Link header
*
* Discovers XRD file for a user by fetching the URL and reading any
* Link: headers in the HTTP response.
*
* @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/
*/
class Discovery_LRDD_Link_Header implements Discovery_LRDD
{
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/**
* Discovery core method
*
* For HTTP IDs fetch the URL and look for Link headers.
*
* @param string $uri URI to inquire about
*
* @return array Links in the XRD file
*
* @todo fail out of Webfinger URIs faster
*/
public function discover($uri)
{
try {
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$client = new HTTPClient();
$response = $client->get($uri);
} catch (HTTP_Request2_Exception $e) {
return false;
}
if ($response->getStatus() != 200) {
return false;
}
$link_header = $response->getHeader('Link');
if (!$link_header) {
// return false;
}
return array(Discovery_LRDD_Link_Header::parseHeader($link_header));
}
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/**
* Given a string or array of headers, returns XRD-like assoc array
*
* @param string|array $header string or array of strings for headers
*
* @return array Link header in XRD-like format
*/
protected static function parseHeader($header)
{
$lh = new LinkHeader($header);
return array('href' => $lh->href,
'rel' => $lh->rel,
'type' => $lh->type);
}
}
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/**
* Implementation of discovery using HTML <link> element
*
* Discovers XRD file for a user by fetching the URL and reading any
* <link> elements in the HTML response.
*
* @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/
*/
class Discovery_LRDD_Link_HTML implements Discovery_LRDD
{
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/**
* Discovery core method
*
* For HTTP IDs, fetch the URL and look for <link> elements
* in the HTML response.
*
* @param string $uri URI to inquire about
*
* @return array Links in XRD-ish assoc array
*
* @todo fail out of Webfinger URIs faster
*/
public function discover($uri)
{
try {
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$client = new HTTPClient();
$response = $client->get($uri);
} catch (HTTP_Request2_Exception $e) {
return false;
}
if ($response->getStatus() != 200) {
return false;
}
return Discovery_LRDD_Link_HTML::parse($response->getBody());
}
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/**
* Parse HTML and return <link> elements
*
* Given an HTML string, scans the string for <link> elements
*
* @param string $html HTML to scan
*
* @return array array of associative arrays in XRD-ish format
*/
public function parse($html)
{
$links = array();
preg_match('/<head(\s[^>]*)?>(.*?)<\/head>/is', $html, $head_matches);
$head_html = $head_matches[2];
preg_match_all('/<link\s[^>]*>/i', $head_html, $link_matches);
foreach ($link_matches[0] as $link_html) {
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$link_url = null;
$link_rel = null;
$link_type = null;
preg_match('/\srel=(("|\')([^\\2]*?)\\2|[^"\'\s]+)/i', $link_html, $rel_matches);
if ( isset($rel_matches[3]) ) {
$link_rel = $rel_matches[3];
} else if ( isset($rel_matches[1]) ) {
$link_rel = $rel_matches[1];
}
preg_match('/\shref=(("|\')([^\\2]*?)\\2|[^"\'\s]+)/i', $link_html, $href_matches);
if ( isset($href_matches[3]) ) {
$link_uri = $href_matches[3];
} else if ( isset($href_matches[1]) ) {
$link_uri = $href_matches[1];
}
preg_match('/\stype=(("|\')([^\\2]*?)\\2|[^"\'\s]+)/i', $link_html, $type_matches);
if ( isset($type_matches[3]) ) {
$link_type = $type_matches[3];
} else if ( isset($type_matches[1]) ) {
$link_type = $type_matches[1];
}
$links[] = array(
'href' => $link_url,
'rel' => $link_rel,
'type' => $link_type,
);
}
return $links;
}
}