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\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                 switch ($url) {
  45                         case 'https://w3id.org/security/v1':
  46                                 $url = DI::baseUrl() . '/static/security-v1.jsonld';
  47                                 break;
  48                         case 'https://w3id.org/identity/v1':
  49                                 $url = DI::baseUrl() . '/static/identity-v1.jsonld';
  50                                 break;
  51                         case 'https://www.w3.org/ns/activitystreams':
  52                                 $url = DI::baseUrl() . '/static/activitystreams.jsonld';
  53                                 break;
  54                         default:
  55                                 Logger::info('Got url', ['url' =>$url]);
  56                                 break;
  57                 }
  58
  59                 $recursion = 0;
  60
  61                 $x = debug_backtrace();
  62                 if ($x) {
  63                         foreach ($x as $n) {
  64                                 if ($n['function'] === __FUNCTION__)  {
  65                                         $recursion ++;
  66                                 }
  67                         }
  68                 }
  69
  70                 if ($recursion > 5) {
  71                         Logger::error('jsonld bomb detected at: ' . $url);
  72                         exit();
  73                 }
  74
  75                 $result = DI::cache()->get('documentLoader:' . $url);
  76                 if (!is_null($result)) {
  77                         return $result;
  78                 }
  79
  80                 $data = jsonld_default_document_loader($url);
  81                 DI::cache()->set('documentLoader:' . $url, $data, Duration::DAY);
  82                 return $data;
  83         }
  84
  85         /**
  86          * Normalises a given JSON array
  87          *
  88          * @param array $json
  89          *
  90          * @return mixed|bool normalized JSON string
  91          * @throws Exception
  92          */
  93         public static function normalize($json)
  94         {
  95                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
  96
  97                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  98
  99                 try {
 100                         $normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
 101                 }
 102                 catch (Exception $e) {
 103                         $normalized = false;
 104                         $messages = [];
 105                         $currentException = $e;
 106                         do {
 107                                 $messages[] = $currentException->getMessage();
 108                         } while($currentException = $currentException->getPrevious());
 109
 110                         Logger::warning('JsonLD normalize error');
 111                         Logger::notice('JsonLD normalize error', ['messages' => $messages]);
 112                         Logger::info('JsonLD normalize error', ['trace' => $e->getTraceAsString()]);
 113                         Logger::debug('JsonLD normalize error', ['jsonobj' => $jsonobj]);
 114                 }
 115
 116                 return $normalized;
 117         }
 118
 119         /**
 120          * Compacts a given JSON array
 121          *
 122          * @param array $json
 123          *
 124          * @return array Compacted JSON array
 125          * @throws Exception
 126          */
 127         public static function compact($json)
 128         {
 129                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
 130
 131                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
 132                         'w3id' => 'https://w3id.org/security#',
 133                         'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
 134                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
 135                         'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
 136                         'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
 137                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
 138                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
 139                         'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id'],
 140                         'litepub' => (object)['@id' => 'http://litepub.social/ns#', '@type' => '@id'],
 141                         'sc' => (object)['@id' => 'http://schema.org#', '@type' => '@id'],
 142                         'pt' => (object)['@id' => 'https://joinpeertube.org/ns#', '@type' => '@id']];
 143
 144                 // Preparation for adding possibly missing content to the context
 145                 if (!empty($json['@context']) && is_string($json['@context'])) {
 146                         $json['@context'] = [$json['@context']];
 147                 }
 148
 149                 // Workaround for servers with missing context
 150                 // See issue https://github.com/nextcloud/social/issues/330
 151                 if (!empty($json['@context']) && is_array($json['@context'])) {
 152                         $json['@context'][] = 'https://w3id.org/security/v1';
 153                 }
 154
 155                 // Trying to avoid memory problems with large content fields
 156                 if (!empty($json['object']['source']['content'])) {
 157                         $content = $json['object']['source']['content'];
 158                         $json['object']['source']['content'] = '';
 159                 }
 160
 161                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 162
 163                 try {
 164                         $compacted = jsonld_compact($jsonobj, $context);
 165                 }
 166                 catch (Exception $e) {
 167                         $compacted = false;
 168                         Logger::error('compacting error', ['line' => $e->getLine(), 'message' => $e->getMessage()]);
 169                 }
 170
 171                 $json = json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
 172
 173                 if (isset($json['as:object']['as:source']['as:content']) && !empty($content)) {
 174                         $json['as:object']['as:source']['as:content'] = $content;
 175                 }
 176
 177                 return $json;
 178         }
 179
 180         /**
 181          * Fetches an element array from a JSON array
 182          *
 183          * @param $array
 184          * @param $element
 185          * @param $key
 186          *
 187          * @return array fetched element
 188          */
 189         public static function fetchElementArray($array, $element, $key = null, $type = null, $type_value = null)
 190         {
 191                 if (!isset($array[$element])) {
 192                         return null;
 193                 }
 194
 195                 // If it isn't an array yet, make it to one
 196                 if (!is_int(key($array[$element]))) {
 197                         $array[$element] = [$array[$element]];
 198                 }
 199
 200                 $elements = [];
 201
 202                 foreach ($array[$element] as $entry) {
 203                         if (!is_array($entry) || is_null($key)) {
 204                                 $item = $entry;
 205                         } elseif (isset($entry[$key])) {
 206                                 $item = $entry[$key];
 207                         }
 208
 209                         if (isset($item) && (is_null($type) || is_null($type_value) || isset($item[$type]) && $item[$type] == $type_value)) {
 210                                 $elements[] = $item;
 211                         }
 212                 }
 213
 214                 return $elements;
 215         }
 216
 217         /**
 218          * Fetches an element from a JSON array
 219          *
 220          * @param $array
 221          * @param $element
 222          * @param $key
 223          * @param $type
 224          * @param $type_value
 225          *
 226          * @return string fetched element
 227          */
 228         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 229         {
 230                 if (empty($array)) {
 231                         return null;
 232                 }
 233
 234                 if (!isset($array[$element])) {
 235                         return null;
 236                 }
 237
 238                 if (!is_array($array[$element])) {
 239                         return $array[$element];
 240                 }
 241
 242                 if (is_null($type) || is_null($type_value)) {
 243                         $element_array = self::fetchElementArray($array, $element, $key);
 244                         if (is_null($element_array)) {
 245                                 return null;
 246                         }
 247
 248                         return array_shift($element_array);
 249                 }
 250
 251                 $element_array = self::fetchElementArray($array, $element);
 252                 if (is_null($element_array)) {
 253                         return null;
 254                 }
 255
 256                 foreach ($element_array as $entry) {
 257                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 258                                 return $entry[$key];
 259                         }
 260                 }
 261
 262                 return null;
 263         }
 264 }