add patch by gmargo to improve favicon detection by content

1 files changed, 27 insertions, 1 deletions

diff --git a/include/functions.php b/include/functions.php
index c19915bb7..6bc3ca4f9 100644
--- a/include/functions.php
+++ b/include/functions.php
@@ -374,7 +374,33 @@
 			$favicon_url = get_favicon_url($site_url);
 
 			if ($favicon_url) {
-				$contents = fetch_file_contents($favicon_url, "image");
+				// Limiting to "image" type misses those served with text/plain
+				$contents = fetch_file_contents($favicon_url); // , "image");
+
+				if ($contents) {
+					// Crude image type matching.
+					// Patterns gleaned from the file(1) source code.
+					if (preg_match('/^\x00\x00\x01\x00/', $contents)) {
+						// 0       string  \000\000\001\000        MS Windows icon resource
+						//error_log("check_feed_favicon: favicon_url=$favicon_url isa MS Windows icon resource");
+					}
+					elseif (preg_match('/^GIF8/', $contents)) {
+						// 0       string          GIF8            GIF image data
+						//error_log("check_feed_favicon: favicon_url=$favicon_url isa GIF image");
+					}
+					elseif (preg_match('/^\x89PNG\x0d\x0a\x1a\x0a/', $contents)) {
+						// 0       string          \x89PNG\x0d\x0a\x1a\x0a         PNG image data
+						//error_log("check_feed_favicon: favicon_url=$favicon_url isa PNG image");
+					}
+					elseif (preg_match('/^\xff\xd8/', $contents)) {
+						// 0       beshort         0xffd8          JPEG image data
+						//error_log("check_feed_favicon: favicon_url=$favicon_url isa JPG image");
+					}
+					else {
+						//error_log("check_feed_favicon: favicon_url=$favicon_url isa UNKNOWN type");
+						$contents = "";
+					}
+				}
 
 				if ($contents) {
 					$fp = @fopen($icon_file, "w");