update jsonfeed detection

lib/XRay/Feeds.php

@@ -55,12 +55,14 @@ class Feeds {
         'url' => $result['url'],
         'type' => 'rss'
       ];
-    } elseif(strpos($contentType, 'application/json') !== false
-      && substr($body, 0, 1) == '{' && strpos(substr($body, 0, 100), 'https://jsonfeed.org/version/1')) {
-      $feeds[] = [
-        'url' => $result['url'],
-        'type' => 'jsonfeed'
-      ];
+    } elseif(strpos($contentType, 'application/json') !== false && substr($body, 0, 1) == '{') {
+      $feeddata = json_decode($body, true);
+      if($feeddata && isset($feeddata['version']) && $feeddata['version'] == 'https://jsonfeed.org/version/1') {
+        $feeds[] = [
+          'url' => $result['url'],
+          'type' => 'jsonfeed'
+        ];
+      }
     } else {
       // Some other document was returned, parse the HTML and look for rel alternates and Microformats
 

lib/XRay/Formats/JSONFeed.php

@@ -10,7 +10,7 @@ class JSONFeed extends Format {
   public static function matches_host($url) { return true; }
   public static function matches($url) { return true; }
 
-  public static function parse($json, $url) {
+  public static function parse($feed, $url) {
     $result = [
       'data' => [
         'type' => 'unknown',
@@ -18,8 +18,6 @@ class JSONFeed extends Format {
       'url' => $url,
     ];
 
-    $feed = json_decode($json, true);
-
     if($feed) {
       $result['data']['type'] = 'feed';
 

lib/XRay/Parser.php

@@ -46,8 +46,11 @@ class Parser {
       return Formats\XML::parse($body, $url);
     }
 
-    if(substr($body, 0, 1) == '{' && strpos(substr($body, 0, 100), 'https://jsonfeed.org/version/1')) {
-      return Formats\JSONFeed::parse($body, $url);
+    if(substr($body, 0, 1) == '{') {
+      $feeddata = json_decode($body, true);
+      if($feeddata && isset($feeddata['version']) && $feeddata['version'] == 'https://jsonfeed.org/version/1') {
+        return Formats\JSONFeed::parse($feeddata, $url);
+      }
     }
 
     // No special parsers matched, parse for Microformats now