src/Util/JsonLD.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2021, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Util;
  23
  24 use Friendica\Core\Cache\Duration;
  25 use Friendica\Core\Logger;
  26 use Exception;
  27 use Friendica\Core\System;
  28 use Friendica\DI;
  29
  30 /**
  31  * This class contain methods to work with JsonLD data
  32  */
  33 class JsonLD
  34 {
  35         /**
  36          * Loader for LD-JSON validation
  37          *
  38          * @param $url
  39          *
  40          * @return mixed the loaded data
  41          * @throws \JsonLdException
  42          */
  43         public static function documentLoader($url)
  44         {
  45                 $recursion = 0;
  46
  47                 $x = debug_backtrace();
  48                 if ($x) {
  49                         foreach ($x as $n) {
  50                                 if ($n['function'] === __FUNCTION__)  {
  51                                         $recursion ++;
  52                                 }
  53                         }
  54                 }
  55
  56                 if ($recursion > 5) {
  57                         Logger::error('jsonld bomb detected at: ' . $url);
  58                         exit();
  59                 }
  60
  61                 $result = DI::cache()->get('documentLoader:' . $url);
  62                 if (!is_null($result)) {
  63                         return $result;
  64                 }
  65
  66                 $data = jsonld_default_document_loader($url);
  67                 DI::cache()->set('documentLoader:' . $url, $data, Duration::DAY);
  68                 return $data;
  69         }
  70
  71         public static function removeSecurityLink(array $json)
  72         {
  73                 if (!is_array($json['@context'])) {
  74                         return $json;
  75                 }
  76
  77                 if (($key = array_search('https://w3id.org/security/v1', $json['@context'])) !== false) {
  78                         unset($json['@context'][$key]);
  79                         $json['@context'] = array_values(array_filter($json['@context']));
  80                 }
  81
  82                 return $json;
  83         }
  84
  85         public static function fixContext(array $json)
  86         {
  87                 // Preparation for adding possibly missing content to the context
  88                 if (!empty($json['@context']) && is_string($json['@context'])) {
  89                         $json['@context'] = [$json['@context']];
  90                 }
  91
  92                 if (($key = array_search('https://w3id.org/security/v1', $json['@context'])) !== false) {
  93                         unset($json['@context'][$key]);
  94                         $json['@context'] = array_values(array_filter($json['@context']));
  95                 }
  96
  97                 $last_entry = count($json['@context']) - 1;
  98
  99                 $additional = [
 100                         'w3id' => 'https://w3id.org/security#',
 101                         'signature' => 'w3id:signature',
 102                         'RsaSignature2017' => 'w3id:RsaSignature2017',
 103                         'created' => 'w3id:created',
 104                         'creator' => 'w3id:creator',
 105                         'nonce' => 'w3id:nonce',
 106                         'signatureValue' => 'w3id:signatureValue',
 107                         'publicKey' => 'w3id:publicKey',
 108                         'publicKeyPem' => 'w3id:publicKeyPem'];
 109
 110                 if (is_array($json['@context'][$last_entry])) {
 111                         $json['@context'][$last_entry] = array_merge($json['@context'][$last_entry], $additional);
 112                 } else {
 113                         $json['@context'][] = $additional;
 114                 }
 115
 116                 return $json;
 117         }
 118
 119         /**
 120          * Normalises a given JSON array
 121          *
 122          * @param array $json
 123          *
 124          * @return mixed|bool normalized JSON string
 125          * @throws Exception
 126          */
 127         public static function normalize($json)
 128         {
 129                 $json = self::removeSecurityLink($json);
 130
 131                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
 132
 133                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 134
 135                 try {
 136                         $normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
 137                 }
 138                 catch (Exception $e) {
 139                         $normalized = false;
 140                         $messages = [];
 141                         $currentException = $e;
 142                         do {
 143                                 $messages[] = $currentException->getMessage();
 144                         } while($currentException = $currentException->getPrevious());
 145
 146                         Logger::warning('JsonLD normalize error');
 147                         Logger::notice('JsonLD normalize error', ['messages' => $messages]);
 148                         Logger::info('JsonLD normalize error', ['trace' => $e->getTraceAsString()]);
 149                         Logger::debug('JsonLD normalize error', ['jsonobj' => $jsonobj]);
 150                 }
 151
 152                 return $normalized;
 153         }
 154
 155         /**
 156          * Compacts a given JSON array
 157          *
 158          * @param array $json
 159          *
 160          * @return array Compacted JSON array
 161          * @throws Exception
 162          */
 163         public static function compact($json)
 164         {
 165                 $json = self::fixContext($json);
 166
 167                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
 168
 169                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
 170                         'w3id' => (object)['@id' => 'https://w3id.org/security#', '@type' => '@id'],
 171                         'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
 172                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
 173                         'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
 174                         'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
 175                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
 176                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
 177                         'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id'],
 178                         'litepub' => (object)['@id' => 'http://litepub.social/ns#', '@type' => '@id'],
 179                         'sc' => (object)['@id' => 'http://schema.org#', '@type' => '@id'],
 180                         'pt' => (object)['@id' => 'https://joinpeertube.org/ns#', '@type' => '@id']];
 181
 182                 // Trying to avoid memory problems with large content fields
 183                 if (!empty($json['object']['source']['content'])) {
 184                         $content = $json['object']['source']['content'];
 185                         $json['object']['source']['content'] = '';
 186                 }
 187
 188                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 189
 190                 try {
 191                         $compacted = jsonld_compact($jsonobj, $context);
 192                 }
 193                 catch (Exception $e) {
 194                         $compacted = false;
 195                         Logger::error('compacting error', ['callstack' => System::callstack(20)]);
 196                         // Sooner or later we should log some details as well - but currently this leads to memory issues
 197                         // Logger::log('compacting error:' . substr(print_r($e, true), 0, 10000), Logger::DEBUG);
 198                 }
 199
 200                 $json = json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
 201
 202                 if (isset($json['as:object']['as:source']['as:content']) && !empty($content)) {
 203                         $json['as:object']['as:source']['as:content'] = $content;
 204                 }
 205
 206                 return $json;
 207         }
 208
 209         /**
 210          * Fetches an element array from a JSON array
 211          *
 212          * @param $array
 213          * @param $element
 214          * @param $key
 215          *
 216          * @return array fetched element
 217          */
 218         public static function fetchElementArray($array, $element, $key = null, $type = null, $type_value = null)
 219         {
 220                 if (!isset($array[$element])) {
 221                         return null;
 222                 }
 223
 224                 // If it isn't an array yet, make it to one
 225                 if (!is_int(key($array[$element]))) {
 226                         $array[$element] = [$array[$element]];
 227                 }
 228
 229                 $elements = [];
 230
 231                 foreach ($array[$element] as $entry) {
 232                         if (!is_array($entry) || is_null($key)) {
 233                                 $item = $entry;
 234                         } elseif (isset($entry[$key])) {
 235                                 $item = $entry[$key];
 236                         }
 237
 238                         if (isset($item) && (is_null($type) || is_null($type_value) || isset($item[$type]) && $item[$type] == $type_value)) {
 239                                 $elements[] = $item;
 240                         }
 241                 }
 242
 243                 return $elements;
 244         }
 245
 246         /**
 247          * Fetches an element from a JSON array
 248          *
 249          * @param $array
 250          * @param $element
 251          * @param $key
 252          * @param $type
 253          * @param $type_value
 254          *
 255          * @return string fetched element
 256          */
 257         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 258         {
 259                 if (empty($array)) {
 260                         return null;
 261                 }
 262
 263                 if (!isset($array[$element])) {
 264                         return null;
 265                 }
 266
 267                 if (!is_array($array[$element])) {
 268                         return $array[$element];
 269                 }
 270
 271                 if (is_null($type) || is_null($type_value)) {
 272                         $element_array = self::fetchElementArray($array, $element, $key);
 273                         if (is_null($element_array)) {
 274                                 return null;
 275                         }
 276
 277                         return array_shift($element_array);
 278                 }
 279
 280                 $element_array = self::fetchElementArray($array, $element);
 281                 if (is_null($element_array)) {
 282                         return null;
 283                 }
 284
 285                 foreach ($element_array as $entry) {
 286                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 287                                 return $entry[$key];
 288                         }
 289                 }
 290
 291                 return null;
 292         }
 293 }