#398

backend/app/services/preview/http_fetcher.rb

@@ -28,11 +28,29 @@ module Preview
           raise FetchFailed, 'redirect が多すぎます．'
         end
 
-        raise FetchFailed, 'redirect 先が不正です．' if location.blank?
+        if location.blank?
+          log_failure(:blank_redirect_location,
+                      url: uri.to_s,
+                      redirects:,
+                      content_type: response['content-type'],
+                      content_length: response['content-length'])
+          raise FetchFailed, 'redirect 先が不正です．'
+        end
 
-        return fetch(URI.join(uri, location).to_s,
-                     max_bytes:,
-                     redirects: redirects - 1)
+        redirect_url =
+            begin
+              URI.join(uri, location).to_s
+            rescue URI::InvalidURIError => e
+              log_failure(:invalid_redirect_location,
+                          url: uri.to_s,
+                          redirects:,
+                          location:,
+                          error: e.class.name,
+                          message: e.message)
+              raise FetchFailed, 'redirect 先が不正です．'
+            end
+
+        return fetch(redirect_url, max_bytes:, redirects: redirects - 1)
       end
 
       unless response.is_a?(Net::HTTPSuccess)