src/Util/JsonLD.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2020, Friendica
   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\DI;
  28
  29 /**
  30  * This class contain methods to work with JsonLD data
  31  */
  32 class JsonLD
  33 {
  34         /**
  35          * Loader for LD-JSON validation
  36          *
  37          * @param $url
  38          *
  39          * @return mixed the loaded data
  40          * @throws \JsonLdException
  41          */
  42         public static function documentLoader($url)
  43         {
  44                 $recursion = 0;
  45
  46                 $x = debug_backtrace();
  47                 if ($x) {
  48                         foreach ($x as $n) {
  49                                 if ($n['function'] === __FUNCTION__)  {
  50                                         $recursion ++;
  51                                 }
  52                         }
  53                 }
  54
  55                 if ($recursion > 5) {
  56                         Logger::error('jsonld bomb detected at: ' . $url);
  57                         exit();
  58                 }
  59
  60                 $result = DI::cache()->get('documentLoader:' . $url);
  61                 if (!is_null($result)) {
  62                         return $result;
  63                 }
  64
  65                 $data = jsonld_default_document_loader($url);
  66                 DI::cache()->set('documentLoader:' . $url, $data, Duration::DAY);
  67                 return $data;
  68         }
  69
  70         /**
  71          * Normalises a given JSON array
  72          *
  73          * @param array $json
  74          *
  75          * @return mixed|bool normalized JSON string
  76          * @throws Exception
  77          */
  78         public static function normalize($json)
  79         {
  80                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
  81
  82                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  83
  84                 try {
  85                         $normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
  86                 }
  87                 catch (Exception $e) {
  88                         $normalized = false;
  89                         $messages = [];
  90                         $currentException = $e;
  91                         do {
  92                                 $messages[] = $currentException->getMessage();
  93                         } while($currentException = $currentException->getPrevious());
  94
  95                         Logger::warning('JsonLD normalize error');
  96                         Logger::notice('JsonLD normalize error', ['messages' => $messages]);
  97                         Logger::info('JsonLD normalize error', ['trace' => $e->getTraceAsString()]);
  98                         Logger::debug('JsonLD normalize error', ['jsonobj' => $jsonobj]);
  99                 }
 100
 101                 return $normalized;
 102         }
 103
 104         /**
 105          * Compacts a given JSON array
 106          *
 107          * @param array $json
 108          *
 109          * @return array Compacted JSON array
 110          * @throws Exception
 111          */
 112         public static function compact($json)
 113         {
 114                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
 115
 116                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
 117                         'w3id' => 'https://w3id.org/security#',
 118                         'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
 119                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
 120                         'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
 121                         'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
 122                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
 123                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
 124                         'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id'],
 125                         'litepub' => (object)['@id' => 'http://litepub.social/ns#', '@type' => '@id']];
 126
 127                 // Preparation for adding possibly missing content to the context
 128                 if (!empty($json['@context']) && is_string($json['@context'])) {
 129                         $json['@context'] = [$json['@context']];
 130                 }
 131
 132                 // Workaround for servers with missing context
 133                 // See issue https://github.com/nextcloud/social/issues/330
 134                 if (!empty($json['@context']) && is_array($json['@context'])) {
 135                         $json['@context'][] = 'https://w3id.org/security/v1';
 136                 }
 137
 138                 // Trying to avoid memory problems with large content fields
 139                 if (!empty($json['object']['source']['content'])) {
 140                         $content = $json['object']['source']['content'];
 141                         $json['object']['source']['content'] = '';
 142                 }
 143
 144                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 145
 146                 try {
 147                         $compacted = jsonld_compact($jsonobj, $context);
 148                 }
 149                 catch (Exception $e) {
 150                         $compacted = false;
 151                         Logger::error('compacting error');
 152                         // Sooner or later we should log some details as well - but currently this leads to memory issues
 153                         // Logger::log('compacting error:' . substr(print_r($e, true), 0, 10000), Logger::DEBUG);
 154                 }
 155
 156                 $json = json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
 157
 158                 if (isset($json['as:object']['as:source']['as:content']) && !empty($content)) {
 159                         $json['as:object']['as:source']['as:content'] = $content;
 160                 }
 161
 162                 return $json;
 163         }
 164
 165         /**
 166          * Fetches an element array from a JSON array
 167          *
 168          * @param $array
 169          * @param $element
 170          * @param $key
 171          *
 172          * @return array fetched element
 173          */
 174         public static function fetchElementArray($array, $element, $key = '@id')
 175         {
 176                 if (empty($array)) {
 177                         return null;
 178                 }
 179
 180                 if (!isset($array[$element])) {
 181                         return null;
 182                 }
 183
 184                 // If it isn't an array yet, make it to one
 185                 if (!is_int(key($array[$element]))) {
 186                         $array[$element] = [$array[$element]];
 187                 }
 188
 189                 $elements = [];
 190
 191                 foreach ($array[$element] as $entry) {
 192                         if (!is_array($entry)) {
 193                                 $elements[] = $entry;
 194                         } elseif (isset($entry[$key])) {
 195                                 $elements[] = $entry[$key];
 196                         } elseif (!empty($entry) || !is_array($entry)) {
 197                                 $elements[] = $entry;
 198                         }
 199                 }
 200
 201                 return $elements;
 202         }
 203
 204         /**
 205          * Fetches an element from a JSON array
 206          *
 207          * @param $array
 208          * @param $element
 209          * @param $key
 210          * @param $type
 211          * @param $type_value
 212          *
 213          * @return string fetched element
 214          */
 215         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 216         {
 217                 if (empty($array)) {
 218                         return null;
 219                 }
 220
 221                 if (!isset($array[$element])) {
 222                         return null;
 223                 }
 224
 225                 if (!is_array($array[$element])) {
 226                         return $array[$element];
 227                 }
 228
 229                 if (is_null($type) || is_null($type_value)) {
 230                         $element_array = self::fetchElementArray($array, $element, $key);
 231                         if (is_null($element_array)) {
 232                                 return null;
 233                         }
 234
 235                         return array_shift($element_array);
 236                 }
 237
 238                 $element_array = self::fetchElementArray($array, $element);
 239                 if (is_null($element_array)) {
 240                         return null;
 241                 }
 242
 243                 foreach ($element_array as $entry) {
 244                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 245                                 return $entry[$key];
 246                         }
 247                 }
 248
 249                 return null;
 250         }
 251 }