Make link checker in MD_STD_RSS_TEST non-final

and the domain is whitelisted

src/MD_STD.php

@@ -775,13 +775,55 @@ final class MD_STD {
             throw new Exception("Failed to get temporary file location");
         }
 
-        $fp = \fopen($tmp_file, 'w');
+        // Check remote headers
 
-        if (!($ch = \curl_init($url))) {
+        if (!($ch_headers = \curl_init())) {
             throw new Exception("Failed to initialize curl for $url");
         };
 
-        \curl_setopt($ch, CURLOPT_FILE, $fp);
+        \curl_setopt_array($ch_headers, [
+            CURLOPT_URL => $url,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_CONNECTTIMEOUT_MS => 10000,
+            CURLOPT_TIMEOUT_MS => 10000,
+            CURLOPT_FOLLOWLOCATION => true,
+            CURLOPT_AUTOREFERER => true,
+            CURLOPT_USERAGENT => 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:10.0.2) Gecko/20100101 Firefox/10.0.2',
+            CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_2_0,
+            CURLOPT_TCP_FASTOPEN => true,
+            CURLOPT_HEADER => true,
+            CURLOPT_NOBODY => true,
+        ]);
+        \curl_exec($ch_headers);
+
+        // If the content length is too high and the request went out to a trusted source,
+        // return the content type as stated by the remote server.
+
+        if (curl_getinfo($ch_headers, CURLINFO_CONTENT_LENGTH_DOWNLOAD_T) > 2000000) {
+            if (($url_parsed = parse_url($url)) && str_contains($url_parsed['host'], 'archive.org') && !empty($remote_content_type = curl_getinfo($ch_headers, CURLINFO_CONTENT_TYPE))) {
+                return $remote_content_type;
+            }
+        }
+
+        // Validate that the remote file really is of the correct content type.
+
+        $fp = \fopen($tmp_file, 'w');
+
+        if (!($ch = \curl_init())) {
+            throw new Exception("Failed to initialize curl for $url");
+        };
+
+        \curl_setopt_array($ch, [
+            CURLOPT_URL => $url,
+            CURLOPT_CONNECTTIMEOUT_MS => 10000,
+            CURLOPT_TIMEOUT_MS => 10000,
+            CURLOPT_FOLLOWLOCATION => true,
+            CURLOPT_AUTOREFERER => true,
+            CURLOPT_USERAGENT => 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:10.0.2) Gecko/20100101 Firefox/10.0.2',
+            CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_2_0,
+            CURLOPT_TCP_FASTOPEN => true,
+            CURLOPT_FILE => $fp,
+        ]);
         \curl_exec($ch);
 
         $mime_type = MD_STD::mime_content_type($tmp_file);

src/testing/MD_STD_RSS_TEST.php

@@ -25,9 +25,22 @@ abstract class MD_STD_RSS_TEST extends TestCase {
 
         $domDoc = new DomDocument();
         self::assertTrue($domDoc->loadXML($this->feed));
-        self::assertTrue($domDoc->schemaValidate(__DIR__ . "/../../assets/xsd/Rss2.xsd"));
+
+        // Don't just validate, but validate after ignoring warning on
+        // the existence of a non-specified <updated/> element.
+        libxml_use_internal_errors(true);
+        $domDoc->schemaValidate(__DIR__ . "/../../assets/xsd/Rss2.xsd");
+        $errors = libxml_get_errors();
         unset($domDoc);
 
+        foreach ($errors as $e) {
+
+            if (str_contains((string)$e->message, '\'updated\': This element is not expected')) {
+                continue;
+            }
+            throw new Exception($e->message);
+        }
+
     }
 
     /**
@@ -35,7 +48,7 @@ abstract class MD_STD_RSS_TEST extends TestCase {
      *
      * @return void
      */
-    final public function testRssFeedLinksAndEnclosure() {
+    public function testRssFeedLinksAndEnclosure() {
 
         if (!($xmlData = simplexml_load_string($this->feed))) {
             throw new Exception("Failed to load RSS feed string to SimpleXML element");