friendica/src/Util/JsonLD.php

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<?php
/**
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* @copyright Copyright (C) 2010-2021, the Friendica project
*
* @license GNU AGPL version 3 or any later version
*
* 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 <https://www.gnu.org/licenses/>.
*
*/
namespace Friendica\Util;
use Friendica\Core\Cache\Duration;
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use Friendica\Core\Logger;
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use Exception;
use Friendica\DI;
/**
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* This class contain methods to work with JsonLD data
*/
class JsonLD
{
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/**
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* Loader for LD-JSON validation
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*
* @param $url
*
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* @return mixed the loaded data
* @throws \JsonLdException
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*/
public static function documentLoader($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, Duration::DAY);
return $data;
}
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public static function fixContext(array $json)
{
// Preparation for adding possibly missing content to the context
if (!empty($json['@context']) && is_string($json['@context'])) {
$json['@context'] = [$json['@context']];
}
if (($key = array_search('https://w3id.org/security/v1', $json['@context'])) !== false) {
unset($json['@context'][$key]);
$json['@context'] = array_values(array_filter($json['@context']));
}
$last_entry = count($json['@context']) - 1;
$additional = [
'w3id' => 'https://w3id.org/security#',
'signature' => 'w3id:signature',
'RsaSignature2017' => 'w3id:RsaSignature2017',
'created' => 'w3id:created',
'creator' => 'w3id:creator',
'nonce' => 'w3id:nonce',
'signatureValue' => 'w3id:signatureValue',
'publicKey' => 'w3id:publicKey',
'publicKeyPem' => 'w3id:publicKeyPem'];
if (is_array($json['@context'][$last_entry])) {
$json['@context'][$last_entry] = array_merge($json['@context'][$last_entry], $additional);
} else {
$json['@context'][] = $additional;
}
return $json;
}
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/**
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* Normalises a given JSON array
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*
* @param array $json
*
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* @return mixed|bool normalized JSON string
* @throws Exception
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*/
public static function normalize($json)
{
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$json = self::fixContext($json);
jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
$jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
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try {
$normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
}
catch (Exception $e) {
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$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]);
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}
return $normalized;
}
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/**
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* Compacts a given JSON array
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*
* @param array $json
*
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* @return array Compacted JSON array
* @throws Exception
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*/
public static function compact($json)
{
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$json = self::fixContext($json);
jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
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$context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
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'w3id' => (object)['@id' => 'https://w3id.org/security#', '@type' => '@id'],
'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
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'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id'],
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'litepub' => (object)['@id' => 'http://litepub.social/ns#', '@type' => '@id'],
'sc' => (object)['@id' => 'http://schema.org#', '@type' => '@id'],
'pt' => (object)['@id' => 'https://joinpeertube.org/ns#', '@type' => '@id']];
// Trying to avoid memory problems with large content fields
if (!empty($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;
}
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/**
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* Fetches an element array from a JSON array
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*
* @param $array
* @param $element
* @param $key
*
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* @return array fetched element
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*/
public static function fetchElementArray($array, $element, $key = null, $type = null, $type_value = null)
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{
if (!isset($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) || is_null($key)) {
$item = $entry;
} elseif (isset($entry[$key])) {
$item = $entry[$key];
}
if (isset($item) && (is_null($type) || is_null($type_value) || isset($item[$type]) && $item[$type] == $type_value)) {
$elements[] = $item;
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}
}
return $elements;
}
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/**
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* Fetches an element from a JSON array
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*
* @param $array
* @param $element
* @param $key
* @param $type
* @param $type_value
*
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* @return string fetched element
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*/
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public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
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{
if (empty($array)) {
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return null;
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}
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if (!isset($array[$element])) {
return null;
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}
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if (!is_array($array[$element])) {
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return $array[$element];
}
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if (is_null($type) || is_null($type_value)) {
$element_array = self::fetchElementArray($array, $element, $key);
if (is_null($element_array)) {
return null;
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}
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return array_shift($element_array);
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}
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$element_array = self::fetchElementArray($array, $element);
if (is_null($element_array)) {
return null;
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}
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foreach ($element_array as $entry) {
if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
return $entry[$key];
}
}
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return null;
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}
}