StoreRemoteMedia plugin to enable locally served thumbs of remote images

Add addPlugin('StoreRemoteMedia'); in your config.php to enable.

plugins/StoreRemoteMedia/StoreRemoteMediaPlugin.php

@@ -0,0 +1,154 @@
+<?php
+
+if (!defined('GNUSOCIAL')) { exit(1); }
+
+// FIXME: To support remote video/whatever files, this plugin needs reworking.
+
+class StoreRemoteMediaPlugin extends Plugin
+{
+    // settings which can be set in config.php with addPlugin('Oembed', array('param'=>'value', ...));
+    // WARNING, these are _regexps_ (slashes added later). Always escape your dots and end your strings
+    public $domain_whitelist = array(       // hostname => service provider
+                                    '^i\d*\.ytimg\.com$' => 'YouTube',
+                                    '^i\d*\.vimeocdn\.com$' => 'Vimeo',
+                                    );
+    public $append_whitelist = array(); // fill this array as domain_whitelist to add more trusted sources
+    public $check_whitelist  = false;    // security/abuse precaution
+
+    protected $imgData = array();
+
+    // these should be declared protected everywhere
+    public function initialize()
+    {
+        parent::initialize();
+
+        $this->domain_whitelist = array_merge($this->domain_whitelist, $this->append_whitelist);
+    }
+
+    /**
+     * Save embedding information for a File, if applicable.
+     *
+     * Normally this event is called through File::saveNew()
+     *
+     * @param File   $file       The newly inserted File object.
+     * @param array  $redir_data lookup data eg from File_redirection::where()
+     * @param string $given_url
+     *
+     * @return boolean success
+     */
+    public function onStartFileSaveNew(array &$redir_data, $given_url)
+    {
+        // save given URL as title if it's a media file this plugin understands
+        // which will make it shown in the AttachmentList widgets
+
+        if (isset($redir_data['title']) && strlen($redir_data['title']>0)) {
+            // Title is already set
+            return true;
+        }
+        if (!isset($redir_data['type'])) {
+            // Unknown mimetype, it's not our job to figure out what it is.
+            return true;
+        }
+        switch (common_get_mime_media($redir_data['type'])) {
+        case 'image':
+            // Just to set something for now at least...
+            $redir_data['title'] = $given_url;
+            break;
+        }
+        
+        return true;
+    }
+
+    public function onCreateFileImageThumbnailSource(File $file, &$imgPath, $media=null)
+    {
+        // If we are on a private node, we won't do any remote calls (just as a precaution until
+        // we can configure this from config.php for the private nodes)
+        if (common_config('site', 'private')) {
+            return true;
+        }
+
+        if ($media !== 'image') {
+            return true;
+        }
+
+        // If there is a local filename, it is either a local file already or has already been downloaded.
+        if (!empty($file->filename)) {
+            return true;
+        }
+
+        $this->checkWhitelist($url);
+
+        // First we download the file to memory and test whether it's actually an image file
+        $imgData = HTTPClient::quickGet($file->getUrl());
+        common_debug(sprintf('Downloading remote file id==%u with URL: %s', $file->id, $file->url));
+        $info = @getimagesizefromstring($imgData);
+        if ($info === false) {
+            throw new UnsupportedMediaException(_('Remote file format was not identified as an image.'), $url);
+        } elseif (!$info[0] || !$info[1]) {
+            throw new UnsupportedMediaException(_('Image file had impossible geometry (0 width or height)'));
+        }
+
+        $filehash = hash(File::FILEHASH_ALG, $imgData);
+        try {
+            // Exception will be thrown before $file is set to anything, so old $file value will be kept
+            $file = File::getByHash($filehash);
+
+            //FIXME: Add some code so we don't have to store duplicate File rows for same hash files.
+        } catch (NoResultException $e) {
+            $filename = $filehash . '.' . common_supported_mime_to_ext($info['mime']);
+            $fullpath = File::path($filename);
+
+            // Write the file to disk if it doesn't exist yet. Throw Exception on failure.
+            if (!file_exists($fullpath) && file_put_contents($fullpath, $imgData) === false) {
+                throw new ServerException(_('Could not write downloaded file to disk.'));
+            }
+
+            // Updated our database for the file record
+            $orig = clone($file);
+            $file->filehash = $filehash;
+            $file->filename = $filename;
+            $file->width = $info[0];    // array indexes documented on php.net:
+            $file->height = $info[1];   // https://php.net/manual/en/function.getimagesize.php
+            // Throws exception on failure.
+            $file->updateWithKeys($orig, 'id');
+        }
+        // Get rid of the file from memory
+        unset($imgData);
+
+        $imgPath = $file->getPath();
+
+        return false;
+    }
+
+    /**
+     * @return boolean          false on no check made, provider name on success
+     * @throws ServerException  if check is made but fails
+     */
+    protected function checkWhitelist($url)
+    {
+        if (!$this->check_whitelist) {
+            return false;   // indicates "no check made"
+        }
+
+        $host = parse_url($url, PHP_URL_HOST);
+        foreach ($this->domain_whitelist as $regex => $provider) {
+            if (preg_match("/$regex/", $host)) {
+                return $provider;    // we trust this source, return provider name
+            }
+        }
+
+        throw new ServerException(sprintf(_('Domain not in remote source whitelist: %s'), $host));
+    }
+
+    public function onPluginVersion(array &$versions)
+    {
+        $versions[] = array('name' => 'StoreRemoteMedia',
+                            'version' => GNUSOCIAL_VERSION,
+                            'author' => 'Mikael Nordfeldth',
+                            'homepage' => 'https://gnu.io/',
+                            'description' =>
+                            // TRANS: Plugin description.
+                            _m('Plugin for downloading remotely attached files to local server.'));
+        return true;
+    }
+}