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 use Friendica\Protocol\ActivityPub;
  30
  31 /**
  32  * This class contain methods to work with JsonLD data
  33  */
  34 class JsonLD
  35 {
  36         /**
  37          * Loader for LD-JSON validation
  38          *
  39          * @param $url
  40          *
  41          * @return mixed the loaded data
  42          * @throws \JsonLdException
  43          */
  44         public static function documentLoader($url)
  45         {
  46                 $recursion = 0;
  47
  48                 $x = debug_backtrace();
  49                 if ($x) {
  50                         foreach ($x as $n) {
  51                                 if ($n['function'] === __FUNCTION__)  {
  52                                         $recursion ++;
  53                                 }
  54                         }
  55                 }
  56
  57                 if ($recursion > 5) {
  58                         Logger::error('jsonld bomb detected at: ' . $url);
  59                         exit();
  60                 }
  61
  62                 $result = DI::cache()->get('documentLoader:' . $url);
  63                 if (!is_null($result)) {
  64                         return $result;
  65                 }
  66
  67                 $data = jsonld_default_document_loader($url);
  68                 DI::cache()->set('documentLoader:' . $url, $data, Duration::DAY);
  69                 return $data;
  70         }
  71
  72         public static function removeSecurityLink(array $json)
  73         {
  74                 if (!is_array($json['@context'])) {
  75                         return $json;
  76                 }
  77
  78                 if (($key = array_search('https://w3id.org/security/v1', $json['@context'])) !== false) {
  79                         unset($json['@context'][$key]);
  80                         $json['@context'] = array_values(array_filter($json['@context']));
  81                 }
  82
  83                 return $json;
  84         }
  85
  86         public static function fixContext(array $json)
  87         {
  88                 // Preparation for adding possibly missing content to the context
  89                 if (!empty($json['@context']) && is_string($json['@context'])) {
  90                         $json['@context'] = [$json['@context']];
  91                 }
  92
  93                 if (($key = array_search('https://w3id.org/security/v1', $json['@context'])) !== false) {
  94                         unset($json['@context'][$key]);
  95                         $json['@context'] = array_values(array_filter($json['@context']));
  96                 }
  97
  98                 $last_entry = count($json['@context']) - 1;
  99
 100                 $additional = [
 101                         'w3id' => 'https://w3id.org/security#',
 102                         'signature' => 'w3id:signature',
 103                         'RsaSignature2017' => 'w3id:RsaSignature2017',
 104                         'created' => 'w3id:created',
 105                         'creator' => 'w3id:creator',
 106                         'nonce' => 'w3id:nonce',
 107                         'signatureValue' => 'w3id:signatureValue',
 108                         'publicKey' => 'w3id:publicKey',
 109                         'publicKeyPem' => 'w3id:publicKeyPem'];
 110
 111                 if (is_array($json['@context'][$last_entry])) {
 112                         $json['@context'][$last_entry] = array_merge($json['@context'][$last_entry], $additional);
 113                 } else {
 114                         $json['@context'][] = $additional;
 115                 }
 116
 117                 return $json;
 118         }
 119
 120         /**
 121          * Normalises a given JSON array
 122          *
 123          * @param array $json
 124          *
 125          * @return mixed|bool normalized JSON string
 126          * @throws Exception
 127          */
 128         public static function normalize($json)
 129         {
 130                 $json = self::removeSecurityLink($json);
 131
 132                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
 133
 134                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 135
 136                 try {
 137                         $normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
 138                 }
 139                 catch (Exception $e) {
 140                         $normalized = false;
 141                         $messages = [];
 142                         $currentException = $e;
 143                         do {
 144                                 $messages[] = $currentException->getMessage();
 145                         } while($currentException = $currentException->getPrevious());
 146
 147                         Logger::warning('JsonLD normalize error');
 148                         Logger::notice('JsonLD normalize error', ['messages' => $messages]);
 149                         Logger::info('JsonLD normalize error', ['trace' => $e->getTraceAsString()]);
 150                         Logger::debug('JsonLD normalize error', ['jsonobj' => $jsonobj]);
 151                 }
 152
 153                 return $normalized;
 154         }
 155
 156         /**
 157          * Compacts a given JSON array
 158          *
 159          * @param array $json
 160          *
 161          * @return array Compacted JSON array
 162          * @throws Exception
 163          */
 164         public static function compact($json)
 165         {
 166                 $context = $json['@context'] ?? [];
 167                 $json['@context'] = ActivityPub::CONTEXT;
 168
 169                 $compacted = self::internalCompact($json);
 170                 if (empty($compacted)) {
 171                         Logger::info('Failed to compact with our context');
 172                         $json['@context'] = $context;
 173                         $compacted = self::internalCompact($json);
 174                         if (empty($compacted)) {
 175                                 Logger::info('Failed to compact with original context');
 176                         } else {
 177                                 Logger::info('Successful compacted with original context');
 178                         }
 179                 }
 180
 181                 return $compacted;
 182         }
 183
 184         private static function internalCompact($json)
 185         {
 186                 $json = self::fixContext($json);
 187
 188                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
 189
 190                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
 191                         'w3id' => (object)['@id' => 'https://w3id.org/security#', '@type' => '@id'],
 192                         'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
 193                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
 194                         'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
 195                         'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
 196                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
 197                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
 198                         'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id'],
 199                         'litepub' => (object)['@id' => 'http://litepub.social/ns#', '@type' => '@id'],
 200                         'sc' => (object)['@id' => 'http://schema.org#', '@type' => '@id'],
 201                         'pt' => (object)['@id' => 'https://joinpeertube.org/ns#', '@type' => '@id']];
 202
 203                 // Trying to avoid memory problems with large content fields
 204                 if (!empty($json['object']['source']['content'])) {
 205                         $content = $json['object']['source']['content'];
 206                         $json['object']['source']['content'] = '';
 207                 }
 208
 209                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 210
 211                 try {
 212                         $compacted = jsonld_compact($jsonobj, $context);
 213                 }
 214                 catch (Exception $e) {
 215                         $compacted = false;
 216                         Logger::error('compacting error', ['line' => $e->getLine(), 'message' => $e->getMessage(),'callstack' => System::callstack(20)]);
 217                 }
 218
 219                 $json = json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
 220
 221                 if (isset($json['as:object']['as:source']['as:content']) && !empty($content)) {
 222                         $json['as:object']['as:source']['as:content'] = $content;
 223                 }
 224
 225                 return $json;
 226         }
 227
 228         /**
 229          * Fetches an element array from a JSON array
 230          *
 231          * @param $array
 232          * @param $element
 233          * @param $key
 234          *
 235          * @return array fetched element
 236          */
 237         public static function fetchElementArray($array, $element, $key = null, $type = null, $type_value = null)
 238         {
 239                 if (!isset($array[$element])) {
 240                         return null;
 241                 }
 242
 243                 // If it isn't an array yet, make it to one
 244                 if (!is_int(key($array[$element]))) {
 245                         $array[$element] = [$array[$element]];
 246                 }
 247
 248                 $elements = [];
 249
 250                 foreach ($array[$element] as $entry) {
 251                         if (!is_array($entry) || is_null($key)) {
 252                                 $item = $entry;
 253                         } elseif (isset($entry[$key])) {
 254                                 $item = $entry[$key];
 255                         }
 256
 257                         if (isset($item) && (is_null($type) || is_null($type_value) || isset($item[$type]) && $item[$type] == $type_value)) {
 258                                 $elements[] = $item;
 259                         }
 260                 }
 261
 262                 return $elements;
 263         }
 264
 265         /**
 266          * Fetches an element from a JSON array
 267          *
 268          * @param $array
 269          * @param $element
 270          * @param $key
 271          * @param $type
 272          * @param $type_value
 273          *
 274          * @return string fetched element
 275          */
 276         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 277         {
 278                 if (empty($array)) {
 279                         return null;
 280                 }
 281
 282                 if (!isset($array[$element])) {
 283                         return null;
 284                 }
 285
 286                 if (!is_array($array[$element])) {
 287                         return $array[$element];
 288                 }
 289
 290                 if (is_null($type) || is_null($type_value)) {
 291                         $element_array = self::fetchElementArray($array, $element, $key);
 292                         if (is_null($element_array)) {
 293                                 return null;
 294                         }
 295
 296                         return array_shift($element_array);
 297                 }
 298
 299                 $element_array = self::fetchElementArray($array, $element);
 300                 if (is_null($element_array)) {
 301                         return null;
 302                 }
 303
 304                 foreach ($element_array as $entry) {
 305                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 306                                 return $entry[$key];
 307                         }
 308                 }
 309
 310                 return null;
 311         }
 312 }