gnu-social/plugins/StoreRemoteMedia/StoreRemoteMediaPlugin.php

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<?php
class StoreRemoteMediaPlugin extends Plugin
{
const PLUGIN_VERSION = '2.0.0';
// settings which can be set in config.php with addPlugin('StoreRemoteMedia', array('param'=>'value', ...));
// WARNING, these are _regexps_ (slashes added later). Always escape your dots and end your strings
public $domain_whitelist = [
// hostname => service provider
'^i\d*\.ytimg\.com$' => 'YouTube',
'^i\d*\.vimeocdn\.com$' => 'Vimeo',
];
public $append_whitelist = []; // fill this array as domain_whitelist to add more trusted sources
public $check_whitelist = false; // security/abuse precaution
public $thumbnail_width = null;
public $thumbnail_height = 128;
public $thumbnail_crop = true;
public $max_size = 10 * 1024 * 1024; // 10MiB max image size by default
protected $imgData = [];
/**
* Initialize the StoreRemoteMedia plugin and set up the environment it needs for it.
* Returns true if it initialized properly, the exception object if it
* doesn't.
*/
public function initialize()
{
parent::initialize();
if (is_null($this->thumbnail_width)) {
$this->thumbnail_width = common_config('thumbnail', 'width');
$this->thumbnail_height = common_config('thumbnail', 'height');
$this->thumbnail_crop = common_config('thumbnail', 'crop');
$this->max_size = common_get_preferred_php_upload_limit();
}
$this->domain_whitelist = array_merge($this->domain_whitelist, $this->append_whitelist);
}
/**
* This event executes when GNU social is creating a file thumbnail entry in
* the database. We glom onto this to fetch remote attachments.
*
* @param $file File the file of the created thumbnail
* @param &$imgPath string = the path to the created thumbnail
* @param $media string = media type
* @return bool
* @throws AlreadyFulfilledException
* @throws FileNotFoundException
* @throws FileNotStoredLocallyException
* @throws HTTP_Request2_Exception
* @throws ServerException
*/
public function onCreateFileImageThumbnailSource(File $file, &$imgPath, string $media): bool
{
// If we are on a private node, we won't do any remote calls (just as a precaution until
// we can configure this from config.php for the private nodes)
if (common_config('site', 'private')) {
return true;
}
// If there is a local filename, it is either a local file already or has already been downloaded.
if (!$file->isStoredRemotely()) {
common_debug(sprintf('File id==%d isn\'t a non-fetched remote file (%s), so nothing StoreRemoteMedia '.
'should handle.', $file->getID(), _ve($file->filename)));
return true;
}
try {
File_thumbnail::byFile($file);
// If we don't get the exception `No result found on File_thumbnail lookup.` then Embed has already handled it most likely.
return true;
} catch (NoResultException $e) {
// We can move on
}
$url = $file->getUrl();
if (substr($url, 0, 7) == 'file://') {
$filename = substr($url, 7);
$info = getimagesize($filename);
$filename = basename($filename);
$width = $info[0];
$height = $info[1];
} else {
$this->checkWhitelist($url);
$head = (new HTTPClient())->head($url);
$headers = $head->getHeader();
$headers = array_change_key_case($headers, CASE_LOWER);
try {
$is_image = $this->isRemoteImage($url, $headers);
if ($is_image == true) {
$file_size = $this->getRemoteFileSize($url, $headers);
if (($file_size!=false) && ($file_size > $this->max_size)) {
common_debug("Went to store remote thumbnail of size " . $file_size .
" but the upload limit is " . $this->max_size . " so we aborted.");
return false;
}
} else {
return false;
}
} catch (Exception $err) {
common_debug("Could not determine size of remote image, aborted local storage.");
throw $err;
}
// First we download the file to memory and test whether it's actually an image file
// FIXME: To support remote video/whatever files, this needs reworking.
common_debug(sprintf(
'Downloading remote image for file id==%u with URL: %s',
$file->getID(),
$url
));
try {
$imgData = HTTPClient::quickGet($url);
if (isset($imgData)) {
list($filename, $filehash, $width, $height) = $this->validateAndWriteImage(
$imgData,
$url,
$headers,
$file->getID()
);
} else {
throw new UnsupportedMediaException('HTTPClient returned an empty result');
}
} catch (UnsupportedMediaException $e) {
// Couldn't find anything that looks like an image, nothing to do
common_debug("StoreRemoteMedia was not able to find an image for URL `{$url}`: " . $e->getMessage());
return false;
}
}
try {
// Update our database for the file record
$orig = clone($file);
$file->filename = $filename;
$file->filehash = $filehash;
$file->width = $width;
$file->height = $height;
// Throws exception on failure.
$file->updateWithKeys($orig);
} catch (Exception $err) {
common_log(LOG_ERR, "Went to update a file entry to the database in " .
"StoreRemoteMediaPlugin::storeRemoteThumbnail but encountered error: ".$err);
throw $err;
}
// Out
$imgPath = $file->getPath();
return !file_exists($imgPath);
}
/**
* Check the file size of a remote file using a HEAD request and checking
* the content-length variable returned. This isn't 100% foolproof but is
* reliable enough for our purposes.
*
* @return string|bool the file size if it succeeds, false otherwise.
*/
private function getRemoteFileSize($url, $headers = null)
{
try {
if ($headers === null) {
if (!common_valid_http_url($url)) {
common_log(LOG_ERR, "Invalid URL in StoreRemoteMedia::getRemoteFileSize()");
return false;
}
$head = (new HTTPClient())->head($url);
$headers = $head->getHeader();
$headers = array_change_key_case($headers, CASE_LOWER);
}
return isset($headers['content-length']) ? $headers['content-length'] : false;
} catch (Exception $err) {
common_log(LOG_ERR, __CLASS__.': getRemoteFileSize on URL : '._ve($url).
' threw exception: '.$err->getMessage());
return false;
}
}
/**
* A private helper function that uses a CURL lookup to check the mime type
* of a remote URL to see it it's an image.
*
* @return bool true if the remote URL is an image, or false otherwise.
*/
private function isRemoteImage($url, $headers = null)
{
if (empty($headers)) {
if (!common_valid_http_url($url)) {
common_log(LOG_ERR, "Invalid URL in StoreRemoteMedia::isRemoteImage()");
return false;
}
$head = (new HTTPClient())->head($url);
$headers = $head->getHeader();
$headers = array_change_key_case($headers, CASE_LOWER);
}
return !empty($headers['content-type']) && common_get_mime_media($headers['content-type']) === 'image';
}
/**
* Validate that $imgData is a valid image before writing it to
* disk, as well as resizing it to at most $this->thumbnail_width
* by $this->thumbnail_height
*
* @param $imgData - The image data to validate. Taken by reference to avoid copying
* @param string|null $url - The url where the image came from, to fetch metadata
* @param array|null $headers - The headers possible previous request to $url
* @param int|null $file_id - The id of the file this image belongs to, used for logging
*/
protected function validateAndWriteImage(&$imgData, ?string $url = null, ?array $headers = null, ?int $file_id = null) : array
{
$info = @getimagesizefromstring($imgData);
// array indexes documented on php.net:
// https://php.net/manual/en/function.getimagesize.php
if ($info === false) {
throw new UnsupportedMediaException(_m('Remote file format was not identified as an image.'), $url);
} elseif (!$info[0] || !$info[1]) {
throw new UnsupportedMediaException(_m('Image file had impossible geometry (0 width or height)'));
}
$width = min($info[0], $this->thumbnail_width);
$height = min($info[1], $this->thumbnail_height);
$filehash = hash(File::FILEHASH_ALG, $imgData);
try {
if (!empty($url)) {
$original_name = HTTPClient::get_filename($url, $headers);
}
$filename = MediaFile::encodeFilename($original_name ?? _m('Untitled attachment'), $filehash);
$filepath = File::path($filename);
// Write the file to disk. Throw Exception on failure
if (!file_exists($filepath)) {
if (strpos($filepath, INSTALLDIR) !== 0 || file_put_contents($filepath, $imgData) === false) {
throw new ServerException(_m('Could not write downloaded file to disk.'));
}
if (common_get_mime_media(MediaFile::getUploadedMimeType($filepath)) !== 'image') {
@unlink($filepath);
throw new UnsupportedMediaException(
_m('Remote file format was not identified as an image.'),
$url
);
}
// If the image is not of the desired size, resize it
if ($info[0] > $this->thumbnail_width || $info[1] > $this->thumbnail_height) {
// Temporary object, not stored in DB
$img = new ImageFile(-1, $filepath);
$box = $img->scaleToFit($this->thumbnail_width, $this->thumbnail_height, $this->thumbnail_crop);
$width = $box['width'];
$height = $box['height'];
$outpath = $img->resizeTo($filepath, $box);
$result = rename($outpath, $filepath);
if (!$result) {
// TRANS: Client exception thrown when a file upload operation fails because the file could
// TRANS: not be moved from the temporary folder to the permanent file location.
// UX: too specific
throw new ClientException(_m('File could not be moved to destination directory.'));
}
}
} else {
throw new AlreadyFulfilledException('A thumbnail seems to already exist for remote file' .
($file_id ? 'with id==' . $file_id : '') . ' at path ' . $filepath);
}
} catch (AlreadyFulfilledException $e) {
// Carry on
} catch (Exception $err) {
common_log(LOG_ERR, "Went to write a thumbnail to disk in StoreRemoteMediaPlugin::storeRemoteThumbnail " .
"but encountered error: {$err}");
throw $err;
} finally {
unset($imgData);
}
return [$filename, $filehash, $width, $height];
}
/**
* @return bool false on no check made, provider name on success
* @throws ServerException if check is made but fails
*/
protected function checkWhitelist($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(_m('Domain not in remote thumbnail source whitelist: %s'), $host));
}
/**
* Event raised when GNU social polls the plugin for information about it.
* Adds this plugin's version information to $versions array
*
* @param &$versions array inherited from parent
* @return bool true hook value
*/
public function onPluginVersion(array &$versions): bool
{
$versions[] = ['name' => 'StoreRemoteMedia',
'version' => self::PLUGIN_VERSION,
'author' => 'Mikael Nordfeldth, Diogo Peralta Cordeiro',
'homepage' => GNUSOCIAL_ENGINE_URL,
'description' =>
// TRANS: Plugin description.
_m('Plugin for downloading remotely attached files to local server.')];
return true;
}
}