src/Util/JsonLD.php

   1 <?php
   2 /**
   3  * @file src/Util/JsonLD.php
   4  */
   5 namespace Friendica\Util;
   6
   7 use Friendica\Core\Cache;
   8 use Friendica\Core\Logger;
   9 use Exception;
  10
  11 /**
  12  * @brief This class contain methods to work with JsonLD data
  13  */
  14 class JsonLD
  15 {
  16         /**
  17          * @brief Loader for LD-JSON validation
  18          *
  19          * @param $url
  20          *
  21          * @return mixed the loaded data
  22          * @throws \JsonLdException
  23          */
  24         public static function documentLoader($url)
  25         {
  26                 $recursion = 0;
  27
  28                 $x = debug_backtrace();
  29                 if ($x) {
  30                         foreach ($x as $n) {
  31                                 if ($n['function'] === __FUNCTION__)  {
  32                                         $recursion ++;
  33                                 }
  34                         }
  35                 }
  36
  37                 if ($recursion > 5) {
  38                         Logger::error('jsonld bomb detected at: ' . $url);
  39                         exit();
  40                 }
  41
  42                 $result = Cache::get('documentLoader:' . $url);
  43                 if (!is_null($result)) {
  44                         return $result;
  45                 }
  46
  47                 $data = jsonld_default_document_loader($url);
  48                 Cache::set('documentLoader:' . $url, $data, Cache::DAY);
  49                 return $data;
  50         }
  51
  52         /**
  53          * @brief Normalises a given JSON array
  54          *
  55          * @param array $json
  56          *
  57          * @return mixed|bool normalized JSON string
  58          * @throws Exception
  59          */
  60         public static function normalize($json)
  61         {
  62                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
  63
  64                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
  65
  66                 try {
  67                         $normalized = jsonld_normalize($jsonobj, array('algorithm' => 'URDNA2015', 'format' => 'application/nquads'));
  68                 }
  69                 catch (Exception $e) {
  70                         $normalized = false;
  71                         Logger::error('normalise error');
  72                         // Sooner or later we should log some details as well - but currently this leads to memory issues
  73                         // Logger::log('normalise error:' . substr(print_r($e, true), 0, 10000), Logger::DEBUG);
  74                 }
  75
  76                 return $normalized;
  77         }
  78
  79         /**
  80          * @brief Compacts a given JSON array
  81          *
  82          * @param array $json
  83          *
  84          * @return array Compacted JSON array
  85          * @throws Exception
  86          */
  87         public static function compact($json)
  88         {
  89                 jsonld_set_document_loader('Friendica\Util\JsonLD::documentLoader');
  90
  91                 $context = (object)['as' => 'https://www.w3.org/ns/activitystreams#',
  92                         'w3id' => 'https://w3id.org/security#',
  93                         'ldp' => (object)['@id' => 'http://www.w3.org/ns/ldp#', '@type' => '@id'],
  94                         'vcard' => (object)['@id' => 'http://www.w3.org/2006/vcard/ns#', '@type' => '@id'],
  95                         'dfrn' => (object)['@id' => 'http://purl.org/macgirvin/dfrn/1.0/', '@type' => '@id'],
  96                         'diaspora' => (object)['@id' => 'https://diasporafoundation.org/ns/', '@type' => '@id'],
  97                         'ostatus' => (object)['@id' => 'http://ostatus.org#', '@type' => '@id'],
  98                         'dc' => (object)['@id' => 'http://purl.org/dc/terms/', '@type' => '@id'],
  99                         'toot' => (object)['@id' => 'http://joinmastodon.org/ns#', '@type' => '@id']];
 100
 101                 // Workaround for Nextcloud Social
 102                 // See issue https://github.com/nextcloud/social/issues/330
 103                 if (!empty($json['@context']) && is_array($json['@context'])) {
 104                         $json['@context'][] = 'https://w3id.org/security/v1';
 105                 }
 106
 107                 // Trying to avoid memory problems with large content fields
 108                 if (!empty($json['object']['source']['content'])) {
 109                         $content = $json['object']['source']['content'];
 110                         $json['object']['source']['content'] = '';
 111                 }
 112
 113                 $jsonobj = json_decode(json_encode($json, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE));
 114
 115                 try {
 116                         $compacted = jsonld_compact($jsonobj, $context);
 117                 }
 118                 catch (Exception $e) {
 119                         $compacted = false;
 120                         Logger::error('compacting error');
 121                         // Sooner or later we should log some details as well - but currently this leads to memory issues
 122                         // Logger::log('compacting error:' . substr(print_r($e, true), 0, 10000), Logger::DEBUG);
 123                 }
 124
 125                 $json = json_decode(json_encode($compacted, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE), true);
 126
 127                 if (isset($json['as:object']['as:source']['as:content']) && !empty($content)) {
 128                         $json['as:object']['as:source']['as:content'] = $content;
 129                 }
 130
 131                 return $json;
 132         }
 133
 134         /**
 135          * @brief Fetches an element array from a JSON array
 136          *
 137          * @param $array
 138          * @param $element
 139          * @param $key
 140          *
 141          * @return array fetched element
 142          */
 143         public static function fetchElementArray($array, $element, $key = '@id')
 144         {
 145                 if (empty($array)) {
 146                         return null;
 147                 }
 148
 149                 if (!isset($array[$element])) {
 150                         return null;
 151                 }
 152
 153                 // If it isn't an array yet, make it to one
 154                 if (!is_int(key($array[$element]))) {
 155                         $array[$element] = [$array[$element]];
 156                 }
 157
 158                 $elements = [];
 159
 160                 foreach ($array[$element] as $entry) {
 161                         if (!is_array($entry)) {
 162                                 $elements[] = $entry;
 163                         } elseif (!empty($entry[$key])) {
 164                                 $elements[] = $entry[$key];
 165                         } elseif (!empty($entry) || !is_array($entry)) {
 166                                 $elements[] = $entry;
 167                         }
 168                 }
 169
 170                 return $elements;
 171         }
 172
 173         /**
 174          * @brief Fetches an element from a JSON array
 175          *
 176          * @param $array
 177          * @param $element
 178          * @param $key
 179          * @param $type
 180          * @param $type_value
 181          *
 182          * @return string fetched element
 183          */
 184         public static function fetchElement($array, $element, $key = '@id', $type = null, $type_value = null)
 185         {
 186                 if (empty($array)) {
 187                         return null;
 188                 }
 189
 190                 if (!isset($array[$element])) {
 191                         return null;
 192                 }
 193
 194                 if (!is_array($array[$element])) {
 195                         return $array[$element];
 196                 }
 197
 198                 if (is_null($type) || is_null($type_value)) {
 199                         $element_array = self::fetchElementArray($array, $element, $key);
 200                         if (is_null($element_array)) {
 201                                 return null;
 202                         }
 203
 204                         return array_shift($element_array);
 205                 }
 206
 207                 $element_array = self::fetchElementArray($array, $element);
 208                 if (is_null($element_array)) {
 209                         return null;
 210                 }
 211
 212                 foreach ($element_array as $entry) {
 213                         if (isset($entry[$key]) && isset($entry[$type]) && ($entry[$type] == $type_value)) {
 214                                 return $entry[$key];
 215                         }
 216                 }
 217
 218                 return null;
 219         }
 220 }