Don't rewrite data URLs (#467)

feed-parsers/class-feed-parser.php

@@ -94,16 +94,21 @@ public function convert_relative_urls_to_absolute_urls( $html, $permalink ) {
 		return preg_replace_callback(
 			'~(src|href)=(?:"([^"]+)|\'([^\']+))~i',
 			function ( $m ) use ( $permalink ) {
+				// Don't update hash-only links.
 				if ( str_starts_with( $m[2], '#' ) ) {
-					// Don't update hash-only links.
 					return $m[0];
 				}
 
+				// Remove absolute URL from hashes so that it can become relative.
 				if ( str_starts_with( $m[2], $permalink . '#' ) ) {
-					// Remove absolute URL from hashes.
 					return str_replace( $permalink, '', $m[0] );
 				}
 
+				// Don't convert content URLs like data:image/png;base64, etc.
+				if ( str_starts_with( $m[2], 'data:' ) ) {
+					return $m[0];
+				}
+
 				// Convert relative URLs to absolute ones.
 				return str_replace( $m[2], Mf2\resolveUrl( $permalink, $m[2] ), $m[0] );
 			},