First steps on converting FeedSub into the pub/sub basis for OStatus communications:

* renamed FeedSub plugin to OStatus
* now setting avatar on subscriptions
* general fixes for subscription
* integrated PuSH hub to handle only user timelines on canonical ID url; sends updates directly
* set $config['feedsub']['nohub'] = true to test w/ foreign feeds that don't have hubs (won't actually receive updates though)
* a few bits of code documentation
* HMAC support for verified distributions (safest if sub setup is on HTTPS)

And a couple core changes:
* minimizing HTML output for exceptions in API requests to aid in debugging
* fix for rel=self link in apitimelineuser when id given

This does not not yet include any of the individual subscription management (Salmon notifications for sub/unsub, etc) nor a nice UI for user subscriptions.
Needs some further cleanup to treat posts as status updates instead of link references.

1 files changed, 221 insertions, 0 deletions

diff --git a/plugins/OStatus/lib/feeddiscovery.php b/plugins/OStatus/lib/feeddiscovery.php
new file mode 100644
index 000000000..9bc7892fb
--- /dev/null
+++ b/plugins/OStatus/lib/feeddiscovery.php
@@ -0,0 +1,221 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2009, 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 FeedSubPlugin
+ * @maintainer Brion Vibber <brion@status.net>
+ */
+
+if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
+
+class FeedSubBadURLException extends FeedSubException
+{
+}
+
+class FeedSubBadResponseException extends FeedSubException
+{
+}
+
+class FeedSubEmptyException extends FeedSubException
+{
+}
+
+class FeedSubBadHTMLException extends FeedSubException
+{
+}
+
+class FeedSubUnrecognizedTypeException extends FeedSubException
+{
+}
+
+class FeedSubNoFeedException extends FeedSubException
+{
+}
+
+/**
+ * Given a web page or feed URL, discover the final location of the feed
+ * and return its current contents.
+ *
+ * @example
+ *   $feed = new FeedDiscovery();
+ *   if ($feed->discoverFromURL($url)) {
+ *     print $feed->uri;
+ *     print $feed->type;
+ *     processFeed($feed->body);
+ *   }
+ */
+class FeedDiscovery
+{
+    public $uri;
+    public $type;
+    public $body;
+
+
+    public function feedMunger()
+    {
+        require_once 'XML/Feed/Parser.php';
+        $feed = new XML_Feed_Parser($this->body, false, false, true); // @fixme
+        return new FeedMunger($feed, $this->uri);
+    }
+
+    /**
+     * @param string $url
+     * @param bool $htmlOk pass false here if you don't want to follow web pages.
+     * @return string with validated URL
+     * @throws FeedSubBadURLException
+     * @throws FeedSubBadHtmlException
+     * @throws FeedSubNoFeedException
+     * @throws FeedSubEmptyException
+     * @throws FeedSubUnrecognizedTypeException
+     */
+    function discoverFromURL($url, $htmlOk=true)
+    {
+        try {
+            $client = new HTTPClient();
+            $response = $client->get($url);
+        } catch (HTTP_Request2_Exception $e) {
+            throw new FeedSubBadURLException($e);
+        }
+
+        if ($htmlOk) {
+            $type = $response->getHeader('Content-Type');
+            $isHtml = preg_match('!^(text/html|application/xhtml\+xml)!i', $type);
+            if ($isHtml) {
+                $target = $this->discoverFromHTML($response->getUrl(), $response->getBody());
+                if (!$target) {
+                    throw new FeedSubNoFeedException($url);
+                }
+                return $this->discoverFromURL($target, false);
+            }
+        }
+        
+        return $this->initFromResponse($response);
+    }
+    
+    function initFromResponse($response)
+    {
+        if (!$response->isOk()) {
+            throw new FeedSubBadResponseException($response->getCode());
+        }
+
+        $sourceurl = $response->getUrl();
+        $body = $response->getBody();
+        if (!$body) {
+            throw new FeedSubEmptyException($sourceurl);
+        }
+
+        $type = $response->getHeader('Content-Type');
+        if (preg_match('!^(text/xml|application/xml|application/(rss|atom)\+xml)!i', $type)) {
+            $this->uri = $sourceurl;
+            $this->type = $type;
+            $this->body = $body;
+            return true;
+        } else {
+            common_log(LOG_WARNING, "Unrecognized feed type $type for $sourceurl");
+            throw new FeedSubUnrecognizedTypeException($type);
+        }
+    }
+
+    /**
+     * @param string $url source URL, used to resolve relative links
+     * @param string $body HTML body text
+     * @return mixed string with URL or false if no target found
+     */
+    function discoverFromHTML($url, $body)
+    {
+        // DOMDocument::loadHTML may throw warnings on unrecognized elements.
+        $old = error_reporting(error_reporting() & ~E_WARNING);
+        $dom = new DOMDocument();
+        $ok = $dom->loadHTML($body);
+        error_reporting($old);
+
+        if (!$ok) {
+            throw new FeedSubBadHtmlException();
+        }
+
+        // Autodiscovery links may be relative to the page's URL or <base href>
+        $base = false;
+        $nodes = $dom->getElementsByTagName('base');
+        for ($i = 0; $i < $nodes->length; $i++) {
+            $node = $nodes->item($i);
+            if ($node->hasAttributes()) {
+                $href = $node->attributes->getNamedItem('href');
+                if ($href) {
+                    $base = trim($href->value);
+                }
+            }
+        }
+        if ($base) {
+            $base = $this->resolveURI($base, $url);
+        } else {
+            $base = $url;
+        }
+
+        // Ok... now on to the links!
+        // @fixme merge with the munger link checks
+        $nodes = $dom->getElementsByTagName('link');
+        for ($i = 0; $i < $nodes->length; $i++) {
+            $node = $nodes->item($i);
+            if ($node->hasAttributes()) {
+                $rel = $node->attributes->getNamedItem('rel');
+                $type = $node->attributes->getNamedItem('type');
+                $href = $node->attributes->getNamedItem('href');
+                if ($rel && $type && $href) {
+                    $rel = trim($rel->value);
+                    $type = trim($type->value);
+                    $href = trim($href->value);
+
+                    $feedTypes = array(
+                        'application/rss+xml',
+                        'application/atom+xml',
+                    );
+                    if (trim($rel) == 'alternate' && in_array($type, $feedTypes)) {
+                        return $this->resolveURI($href, $base);
+                    }
+                }
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Resolve a possibly relative URL against some absolute base URL
+     * @param string $rel relative or absolute URL
+     * @param string $base absolute URL
+     * @return string absolute URL, or original URL if could not be resolved.
+     */
+    function resolveURI($rel, $base)
+    {
+        require_once "Net/URL2.php";
+        try {
+            $relUrl = new Net_URL2($rel);
+            if ($relUrl->isAbsolute()) {
+                return $rel;
+            }
+            $baseUrl = new Net_URL2($base);
+            $absUrl = $baseUrl->resolve($relUrl);
+            return $absUrl->getURL();
+        } catch (Exception $e) {
+            common_log(LOG_WARNING, 'Unable to resolve relative link "' .
+                $rel . '" against base "' . $base . '": ' . $e->getMessage());
+            return $rel;
+        }
+    }
+}