discovery piece - hand merged :P

plugins/OStatus/OStatusPlugin.php

@@ -53,6 +53,19 @@ class OStatusPlugin extends Plugin
      */
     function onRouterInitialized($m)
     {
+        $m->connect('.well-known/host-meta',
+                    array('action' => 'hostmeta'));
+        $m->connect('main/webfinger',
+                    array('action' => 'webfinger'));
+        $m->connect('main/ostatus',
+                    array('action' => 'ostatusinit'));
+        $m->connect('main/ostatus?nickname=:nickname',
+                  array('action' => 'ostatusinit'), array('nickname' => '[A-Za-z0-9_-]+'));
+        $m->connect('main/ostatussub',
+                    array('action' => 'ostatussub'));          
+        $m->connect('main/ostatussub',
+                    array('action' => 'ostatussub'), array('feed' => '[A-Za-z0-9\.\/\:]+'));          
+        
         $m->connect('main/push/hub', array('action' => 'pushhub'));
 
         $m->connect('main/push/callback/:feed',
@@ -148,6 +161,28 @@ class OStatusPlugin extends Plugin
         return true;
     }
 
+    /**
+     * Add in an OStatus subscribe button
+     */
+    function onStartProfilePageActionsElements($output, $profile)
+    {
+        $cur = common_current_user();
+
+        if (empty($cur)) {
+            // Add an OStatus subscribe
+            $output->elementStart('li', 'entity_subscribe');
+            $url = common_local_url('ostatusinit',
+                                    array('nickname' => $profile->nickname));
+            $output->element('a', array('href' => $url,
+                                        'class' => 'entity_remote_subscribe'),
+                                _('OStatus'));
+            
+            $output->elementEnd('li');
+        }
+    }
+    
+
+    
     function onCheckSchema() {
         // warning: the autoincrement doesn't seem to set.
         // alter table feedinfo change column id id int(11) not null  auto_increment;

plugins/OStatus/actions/hostmeta.php

@@ -0,0 +1,42 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * 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/>.
+ */
+
+/**
+ * @package OStatusPlugin
+ * @maintainer James Walker <james@status.net>
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
+
+class HostMetaAction extends Action
+{
+
+    function handle()
+    {
+        parent::handle();
+
+        $w = new Webfinger();
+
+
+        $domain = common_config('site', 'server');
+        $url = common_local_url('webfinger');
+        $url.= '?uri={uri}';
+        print $w->getHostMeta($domain, $url);
+    }
+}

plugins/OStatus/actions/ostatusinit.php

@@ -0,0 +1,128 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * 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/>.
+ */
+
+/**
+ * @package OStatusPlugin
+ * @maintainer James Walker <james@status.net>
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
+
+
+class OStatusInitAction extends Action
+{
+
+    var $nickname;
+    var $acct;
+    var $err;
+
+    function prepare($args)
+    {
+        parent::prepare($args);
+
+        if (common_logged_in()) {
+            $this->clientError(_('You can use the local subscription!'));
+            return false;
+        }
+
+        $this->nickname    = $this->trimmed('nickname');
+        $this->acct = $this->trimmed('acct');
+
+        return true;
+    }
+    
+    function handle($args)
+    {
+        parent::handle($args);
+
+        if ($_SERVER['REQUEST_METHOD'] == 'POST') {
+            /* Use a session token for CSRF protection. */
+            $token = $this->trimmed('token');
+            if (!$token || $token != common_session_token()) {
+                $this->showForm(_('There was a problem with your session token. '.
+                                  'Try again, please.'));
+                return;
+            }
+            $this->ostatusConnect();
+        } else {
+            $this->showForm();
+        }
+    }
+    
+    function showForm($err = null)
+    {
+      $this->err = $err;
+      $this->showPage();
+
+    }
+
+    function showContent()
+    {
+        $this->elementStart('form', array('id' => 'form_ostatus_connect',
+                                          'method' => 'post',
+                                          'class' => 'form_settings',
+                                          'action' => common_local_url('ostatusinit')));
+        $this->elementStart('fieldset');
+        $this->element('legend', _('Subscribe to a remote user'));
+        $this->hidden('token', common_session_token());
+
+        $this->elementStart('ul', 'form_data');
+        $this->elementStart('li');
+        $this->input('nickname', _('User nickname'), $this->nickname,
+                     _('Nickname of the user you want to follow'));
+        $this->elementEnd('li');
+        $this->elementStart('li');
+        $this->input('acct', _('Profile Account'), $this->acct,
+                     _('Your account id (i.e. user@identi.ca)'));
+        $this->elementEnd('li');
+        $this->elementEnd('ul');
+        $this->submit('submit', _('Subscribe'));
+        $this->elementEnd('fieldset');
+        $this->elementEnd('form');
+    }        
+
+    function ostatusConnect()
+    {
+      $w = new Webfinger;
+
+      $result = $w->lookup($this->acct);
+      foreach ($result->links as $link) {
+          if ($link['rel'] == 'http://ostatus.org/schema/1.0/subscribe') {
+              // We found a URL - let's redirect!
+
+              $user = User::staticGet('nickname', $this->nickname);
+
+              $feed_url = common_local_url('ApiTimelineUser',
+                                           array('id' => $user->id,
+                                                 'format' => 'atom'));
+              $url = $w->applyTemplate($link['template'], $feed_url);
+
+              common_redirect($url, 303);
+          }
+
+      }
+      
+    }
+    
+    function title()
+    {
+      return _('OStatus Connect');  
+    }
+  
+}

plugins/OStatus/actions/ostatussub.php

@@ -0,0 +1,226 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * 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/>.
+ */
+
+/**
+ * @package OStatusPlugin
+ * @maintainer James Walker <james@status.net>
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
+
+class OStatusSubAction extends Action
+{
+
+    protected $feedurl;
+    
+    function title()
+    {
+        return _m("OStatus Subscribe");
+    }
+
+    function handle($args)
+    {
+        if ($this->validateFeed()) {
+            $this->showForm();
+        }
+
+        return true;
+
+    }
+
+    function showForm($err = null)
+    {
+        $this->err = $err;
+        $this->showPage();
+    }
+
+
+    function showContent()
+    {
+        $user = common_current_user();
+
+        $profile = $user->getProfile();
+
+        $fuser = null;
+
+        $flink = Foreign_link::getByUserID($user->id, FEEDSUB_SERVICE);
+
+        if (!empty($flink)) {
+            $fuser = $flink->getForeignUser();
+        }
+
+        $this->elementStart('form', array('method' => 'post',
+                                          'id' => 'form_settings_feedsub',
+                                          'class' => 'form_settings',
+                                          'action' =>
+                                          common_local_url('feedsubsettings')));
+
+        $this->hidden('token', common_session_token());
+
+        $this->elementStart('fieldset', array('id' => 'settings_feeds'));
+
+        $this->elementStart('ul', 'form_data');
+        $this->elementStart('li', array('id' => 'settings_twitter_login_button'));
+        $this->input('feedurl', _('Feed URL'), $this->feedurl, _('Enter the URL of a PubSubHubbub-enabled feed'));
+        $this->elementEnd('li');
+        $this->elementEnd('ul');
+
+        $this->submit('subscribe', _m('Subscribe'));
+
+        $this->elementEnd('fieldset');
+
+        $this->elementEnd('form');
+
+        $this->previewFeed();
+    }
+
+    /**
+     * Handle posts to this form
+     *
+     * Based on the button that was pressed, muxes out to other functions
+     * to do the actual task requested.
+     *
+     * All sub-functions reload the form with a message -- success or failure.
+     *
+     * @return void
+     */
+
+    function handlePost()
+    {
+        // CSRF protection
+        $token = $this->trimmed('token');
+        if (!$token || $token != common_session_token()) {
+            $this->showForm(_('There was a problem with your session token. '.
+                              'Try again, please.'));
+            return;
+        }
+
+        if ($this->arg('subscribe')) {
+            $this->saveFeed();
+        } else {
+            $this->showForm(_('Unexpected form submission.'));
+        }
+    }
+
+    
+    /**
+     * Set up and add a feed
+     *
+     * @return boolean true if feed successfully read
+     * Sends you back to input form if not.
+     */
+    function validateFeed()
+    {
+        $feedurl = $this->trimmed('feed');
+        
+        if ($feedurl == '') {
+            $this->showForm(_m('Empty feed URL!'));
+            return;
+        }
+        $this->feedurl = $feedurl;
+        
+        // Get the canonical feed URI and check it
+        try {
+            $discover = new FeedDiscovery();
+            $uri = $discover->discoverFromURL($feedurl);
+        } catch (FeedSubBadURLException $e) {
+            $this->showForm(_m('Invalid URL or could not reach server.'));
+            return false;
+        } catch (FeedSubBadResponseException $e) {
+            $this->showForm(_m('Cannot read feed; server returned error.'));
+            return false;
+        } catch (FeedSubEmptyException $e) {
+            $this->showForm(_m('Cannot read feed; server returned an empty page.'));
+            return false;
+        } catch (FeedSubBadHTMLException $e) {
+            $this->showForm(_m('Bad HTML, could not find feed link.'));
+            return false;
+        } catch (FeedSubNoFeedException $e) {
+            $this->showForm(_m('Could not find a feed linked from this URL.'));
+            return false;
+        } catch (FeedSubUnrecognizedTypeException $e) {
+            $this->showForm(_m('Not a recognized feed type.'));
+            return false;
+        } catch (FeedSubException $e) {
+            // Any new ones we forgot about
+            $this->showForm(_m('Bad feed URL.'));
+            return false;
+        }
+        
+        $this->munger = $discover->feedMunger();
+        $this->feedinfo = $this->munger->feedInfo();
+
+        if ($this->feedinfo->huburi == '') {
+            $this->showForm(_m('Feed is not PuSH-enabled; cannot subscribe.'));
+            return false;
+        }
+        
+        return true;
+    }
+
+    function saveFeed()
+    {
+        if ($this->validateFeed()) {
+            $this->preview = true;
+            $this->feedinfo = Feedinfo::ensureProfile($this->munger);
+
+            // If not already in use, subscribe to updates via the hub
+            if ($this->feedinfo->sub_start) {
+                common_log(LOG_INFO, __METHOD__ . ": double the fun! new sub for {$this->feedinfo->feeduri} last subbed {$this->feedinfo->sub_start}");
+            } else {
+                $ok = $this->feedinfo->subscribe();
+                common_log(LOG_INFO, __METHOD__ . ": sub was $ok");
+                if (!$ok) {
+                    $this->showForm(_m('Feed subscription failed! Bad response from hub.'));
+                    return;
+                }
+            }
+            
+            // And subscribe the current user to the local profile
+            $user = common_current_user();
+            $profile = $this->feedinfo->getProfile();
+            
+            if ($user->isSubscribed($profile)) {
+                $this->showForm(_m('Already subscribed!'));
+            } elseif ($user->subscribeTo($profile)) {
+                $this->showForm(_m('Feed subscribed!'));
+            } else {
+                $this->showForm(_m('Feed subscription failed!'));
+            }
+        }
+    }
+
+    
+    function previewFeed()
+    {
+        $feedinfo = $this->munger->feedinfo();
+        $notice = $this->munger->notice(0, true); // preview
+
+        if ($notice) {
+            $this->element('b', null, 'Preview of latest post from this feed:');
+
+            $item = new NoticeList($notice, $this);
+            $item->show();
+        } else {
+            $this->element('b', null, 'No posts in this feed yet.');
+        }
+    }
+
+
+}

plugins/OStatus/actions/webfinger.php

@@ -0,0 +1,70 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * 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/>.
+ */
+
+/**
+ * @package OStatusPlugin
+ * @maintainer James Walker <james@status.net>
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
+
+class WebfingerAction extends Action
+{
+
+    public $uri;
+
+    function prepare($args)
+    {
+        parent::prepare($args);
+
+        $this->uri = $this->trimmed('uri');
+
+        return true;
+    }
+        
+    function handle()
+    {
+        $acct = Webfinger::normalize($this->uri);
+
+        $xrd = new XRD();
+
+        list($nick, $domain) = explode('@', urldecode($acct));
+        $nick = common_canonical_nickname($nick);
+
+        $this->user = User::staticGet('nickname', $nick);
+        if (!$this->user) {
+            $this->clientError(_('No such user.'), 404);
+            return false;
+        }
+
+        $xrd->subject = $this->uri;
+        $xrd->alias[] = common_profile_url($nick);
+        $xrd->links[] = array('rel' => 'http://webfinger.net/rel/profile-page',
+                              'type' => 'text/html',
+                              'href' => common_profile_url($nick));
+        // TODO - finalize where the redirect should go on the publisher
+        $url = common_local_url('ostatussub') . '?feed={uri}';
+        $xrd->links[] = array('rel' => 'http://ostatus.org/schema/1.0/subscribe',
+                              'template' => $url );
+
+        header('Content-type: text/xml');
+        print $xrd->toXML();
+    }
+
+}

plugins/OStatus/lib/Webfinger.php

@@ -0,0 +1,139 @@
+<?php
+/**
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * A sample module to show best practices for StatusNet plugins
+ *
+ * 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/>.
+ *
+ * @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/
+ */
+
+define('WEBFINGER_SERVICE_REL_VALUE', 'lrdd');
+
+/**
+ * Implement the webfinger protocol.
+ */
+class Webfinger
+{
+    /**
+     * Perform a webfinger lookup given an account.
+     */ 
+    public function lookup($id)
+    {
+        $id = $this->normalize($id);
+        list($name, $domain) = explode('@', $id);
+
+        $links = $this->getServiceLinks($domain);
+        if (!$links) {
+            return false;
+        }
+        
+        $services = array();
+        foreach ($links as $link) {
+            if ($link['template']) {
+                return $this->getServiceDescription($link['template'], $id);
+            }
+            if ($link['href']) {
+                return $this->getServiceDescription($link['href'], $id);
+            }
+        }
+    }
+
+    /**
+     * Normalize an account ID
+     */
+    function normalize($id)
+    {
+        if (substr($id, 0, 7) == 'acct://') {
+            return substr($id, 7); 
+        } else if (substr($id, 0, 5) == 'acct:') {
+            return substr($id, 5);
+        }
+
+        return $id;
+    }
+
+    function getServiceLinks($domain)
+    {
+        $url = 'http://'. $domain .'/.well-known/host-meta';
+        $content = $this->fetchURL($url);
+        $result = XRD::parse($content);
+
+        // Ensure that the host == domain (spec may include signing later)
+        if ($result->host != $domain) {
+            return false;
+        }
+        
+        $links = array();
+        foreach ($result->links as $link) {
+            if ($link['rel'] == WEBFINGER_SERVICE_REL_VALUE) {
+                $links[] = $link;
+            }
+
+        }
+        return $links;
+    }
+
+    function getServiceDescription($template, $id)
+    {
+        $url = $this->applyTemplate($template, 'acct:' . $id);
+
+        $content = $this->fetchURL($url);
+
+        return XRD::parse($content);
+    }
+
+    function fetchURL($url)
+    {
+        try {
+            $client = new HTTPClient();
+            $response = $client->get($url);
+        } catch (HTTP_Request2_Exception $e) {
+            return false;
+        }
+
+        if ($response->getStatus() != 200) {
+            return false;
+        }
+
+        return $response->getBody();
+    }
+
+    function applyTemplate($template, $id)
+    {
+        $template = str_replace('{uri}', urlencode($id), $template);
+
+        return $template;
+    }
+
+    function getHostMeta($domain, $template) {
+        $xrd = new XRD();
+        $xrd->host = $domain;
+        $xrd->links[] = array('rel' => 'lrdd',
+                              'template' => $template,
+                              'title' => array('Resource Descriptor'));
+
+        return $xrd->toXML();
+    }
+}
+
+

plugins/OStatus/lib/XRD.php

@@ -0,0 +1,183 @@
+<?php
+/**
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2010, StatusNet, Inc.
+ *
+ * A sample module to show best practices for StatusNet plugins
+ *
+ * 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/>.
+ *
+ * @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 XRD
+{
+    const XML_NS = 'http://www.w3.org/2000/xmlns/';
+    
+    const XRD_NS = 'http://docs.oasis-open.org/ns/xri/xrd-1.0';
+
+    const HOST_META_NS = 'http://host-meta.net/xrd/1.0';
+    
+    public $expires;
+
+    public $subject;
+
+    public $host;
+
+    public $alias = array();
+    
+    public $types = array();
+    
+    public $links = array();
+    
+    public static function parse($xml)
+    {
+        $xrd = new XRD();
+
+        $dom = new DOMDocument();
+        $dom->loadXML($xml);
+        $xrd_element = $dom->getElementsByTagName('XRD')->item(0);
+
+        // Check for host-meta host
+        $host = $xrd_element->getElementsByTagName('Host')->item(0)->nodeValue;
+        if ($host) {
+            $xrd->host = $host;
+        }
+
+        // Loop through other elements
+        foreach ($xrd_element->childNodes as $node) {
+            switch ($node->tagName) {
+            case 'Expires':
+                $xrd->expires = $node->nodeValue;
+                break;
+            case 'Subject':
+                $xrd->subject = $node->nodeValue;
+                break;
+                
+            case 'Alias':
+                $xrd->alias[] = $node->nodeValue;
+                break;
+
+            case 'Link':
+                $xrd->links[] = $xrd->parseLink($node);
+                break;
+
+            case 'Type':
+                $xrd->types[] = $xrd->parseType($node);
+                break;
+
+            }
+        }
+        return $xrd;
+    }
+
+    public function toXML()
+    {
+        $dom = new DOMDocument('1.0', 'UTF-8');
+        $dom->formatOutput = true;
+        
+        $xrd_dom = $dom->createElementNS(XRD::XRD_NS, 'XRD');
+        $dom->appendChild($xrd_dom);
+
+        if ($this->host) {
+            $host_dom = $dom->createElement('hm:Host', $this->host);
+            $xrd_dom->setAttributeNS(XRD::XML_NS, 'xmlns:hm', XRD::HOST_META_NS);
+            $xrd_dom->appendChild($host_dom);
+        }
+        
+		if ($this->expires) {
+			$expires_dom = $dom->createElement('Expires', $this->expires);
+			$xrd_dom->appendChild($expires_dom);
+		}
+
+		if ($this->subject) {
+			$subject_dom = $dom->createElement('Subject', $this->subject);
+			$xrd_dom->appendChild($subject_dom);
+		}
+
+		foreach ($this->alias as $alias) {
+			$alias_dom = $dom->createElement('Alias', $alias);
+			$xrd_dom->appendChild($alias_dom);
+		}
+
+		foreach ($this->types as $type) {
+			$type_dom = $dom->createElement('Type', $type);
+			$xrd_dom->appendChild($type_dom);
+		}
+
+		foreach ($this->links as $link) {
+			$link_dom = $this->saveLink($dom, $link);
+			$xrd_dom->appendChild($link_dom);
+		}
+
+        return $dom->saveXML();
+    }
+
+    function parseType($element)
+    {
+        return array();
+    }
+    
+    function parseLink($element)
+    {
+        $link = array();
+        $link['rel'] = $element->getAttribute('rel');
+        $link['type'] = $element->getAttribute('type');
+        $link['href'] = $element->getAttribute('href');
+        $link['template'] = $element->getAttribute('template');
+        foreach ($element->childNodes as $node) {
+            switch($node->tagName) {
+            case 'Title':
+                $link['title'][] = $node->nodeValue;
+            }
+        }
+
+        return $link;
+    }
+
+    function saveLink($doc, $link)
+    {
+        $link_element = $doc->createElement('Link');
+        if ($link['rel']) {
+            $link_element->setAttribute('rel', $link['rel']);
+        }
+        if ($link['type']) {
+            $link_element->setAttribute('type', $link['type']);
+        }
+        if ($link['href']) {
+            $link_element->setAttribute('href', $link['href']);
+        }
+        if ($link['template']) {
+            $link_element->setAttribute('template', $link['template']);
+        }
+
+        if (is_array($link['title'])) {
+            foreach($link['title'] as $title) {
+                $title = $doc->createElement('Title', $title);
+                $link_element->appendChild($title);
+            }
+        }
+
+        
+        return $link_element;
+    }
+}
+