Friendica Communications Platform (please note that this is a clone of the repository at github, issues are handled there) https://friendi.ca
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<?php
/**
* @file src/Util/JsonLD.php
*/
namespace Friendica\Util;
use Friendica\Core\Cache\Cache;
use Friendica\Core\Logger;
use Exception;
use Friendica\DI;
/**
* @brief This class contain methods to work with JsonLD data
*/
class JsonLD
{
/**
* @brief Loader for LD-JSON validation
*
* @param $url
*
* @return mixed the loaded data
* @throws \JsonLdException
*/
public static function documentLoader($url)
{
$recursion = 0;
$x = debug_backtrace();
if ($x) {
foreach ($x as $n) {
if ($n['function'] === __FUNCTION__) {
$recursion ++;
}
}
}
if ($recursion > 5) {
Logger::error('jsonld bomb detected at: ' . $url);
exit();
}
$result = DI::cache()->get('documentLoader:' . $url);
if (!is_null($result)) {
return $result;
}
$data = jsonld_default_document_loader($url);
DI::cache()->set('documentLoader:' . $url, $data, Cache::DAY);
return $data;
}
/**
* @brief Normalises a given JSON array
*
* @param array $json
*
* @return mixed|bool normalized JSON string
* @throws Exception
*/
public static function normalize($json)
{
jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
$jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
try {
$normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
}
catch (Exception $e) {
$normalized = false;
$messages = [];
$currentException = $e;
do {
$messages[] = $currentException->getMessage();
} while($currentException = $currentException->getPrevious());
Logger::warning('JsonLD normalize error');
Logger::notice('JsonLD normalize error', ['messages' => $messages]);
Logger::info('JsonLD normalize error', ['trace' => $e->getTraceAsString()]);
Logger::debug('JsonLD normalize error', ['jsonobj' => $jsonobj]);
}
return $normalized;
}
/**
* @brief Compacts a given JSON array
*
* @param array $json
*
* @return array Compacted JSON array
* @throws Exception
*/
public static function compact($json)
{
jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
$context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
'w3id' => 'https://w3id.org/security#',
'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id'],
'litepub' => (object)['@id' => 'http://litepub.social/ns#', '@type' => '@id']];
// Preparation for adding possibly missing content to the context
if (!empty($json['@context']) && is_string($json['@context'])) {
$json['@context'] = [$json['@context']];
}
// Workaround for servers with missing context
// See issue https://github.com/nextcloud/social/issues/330
if (!empty($json['@context']) && is_array($json['@context'])) {
$json['@context'][] = 'https://w3id.org/security/v1';
}
// Trying to avoid memory problems with large content fields
if (!empty($json['object']['source']['content'])) {
$content = $json['object']['source']['content'];
$json['object']['source']['content'] = '';
}
$jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
try {
$compacted = jsonld_compact($jsonobj, $context);
}
catch (Exception $e) {
$compacted = false;
Logger::error('compacting error');
// Sooner or later we should log some details as well - but currently this leads to memory issues
// Logger::log('compacting error:' . substr(print_r($e, true), 0, 10000), Logger::DEBUG);
}
$json = json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
if (isset($json['as:object']['as:source']['as:content']) && !empty($content)) {
$json['as:object']['as:source']['as:content'] = $content;
}
return $json;
}
/**
* @brief Fetches an element array from a JSON array
*
* @param $array
* @param $element
* @param $key
*
* @return array fetched element
*/
public static function fetchElementArray($array, $element, $key = '@id')
{
if (empty($array)) {
return null;
}
if (!isset($array[$element])) {
return null;
}
// If it isn't an array yet, make it to one
if (!is_int(key($array[$element]))) {
$array[$element] = [$array[$element]];
}
$elements = [];
foreach ($array[$element] as $entry) {
if (!is_array($entry)) {
$elements[] = $entry;
} elseif (isset($entry[$key])) {
$elements[] = $entry[$key];
} elseif (!empty($entry) || !is_array($entry)) {
$elements[] = $entry;
}
}
return $elements;
}
/**
* @brief Fetches an element from a JSON array
*
* @param $array
* @param $element
* @param $key
* @param $type
* @param $type_value
*
* @return string fetched element
*/
public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
{
if (empty($array)) {
return null;
}
if (!isset($array[$element])) {
return null;
}
if (!is_array($array[$element])) {
return $array[$element];
}
if (is_null($type) || is_null($type_value)) {
$element_array = self::fetchElementArray($array, $element, $key);
if (is_null($element_array)) {
return null;
}
return array_shift($element_array);
}
$element_array = self::fetchElementArray($array, $element);
if (is_null($element_array)) {
return null;
}
foreach ($element_array as $entry) {
if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
return $entry[$key];
}
}
return null;
}
}