From 07df36898e336ee6473b789d3fc78a7b95194b34 Mon Sep 17 00:00:00 2001
From: Stefan Strigler <stefan@strigler.de>
Date: Thu, 9 Jan 2025 08:22:52 +0100
Subject: [PATCH] mod_spam_filters: gracefully handle missing location header

---
 mod_spam_filter/src/mod_spam_filter.erl | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/mod_spam_filter/src/mod_spam_filter.erl b/mod_spam_filter/src/mod_spam_filter.erl
index 5e9ad82a..7c8af31a 100644
--- a/mod_spam_filter/src/mod_spam_filter.erl
+++ b/mod_spam_filter/src/mod_spam_filter.erl
@@ -441,13 +441,17 @@ do_resolve_redirects([URL | Rest], Acc) ->
                       [{autoredirect, false}, {timeout, ?HTTPC_TIMEOUT}], [])
     of
         {ok, {{_, Moved, _}, Headers, _Body}} when Moved >= 300, Moved < 400 ->
-            Location = proplists:get_value("location", Headers),
-            case lists:member(Location, Acc) of
-                false ->
-                    do_resolve_redirects([Location | Rest], [URL | Acc]);
-                true ->
-                    do_resolve_redirects(Rest, [URL | Acc])
-            end;
+            case proplists:get_value("location", Headers) of
+                undefined ->
+                    do_resolve_redirects(Rest, Acc);
+                Location ->
+                    case lists:member(Location, Acc) of
+                        false ->
+                            do_resolve_redirects([Location | Rest], [URL | Acc]);
+                        true ->
+                            do_resolve_redirects(Rest, [URL | Acc])
+                    end
+              end;
         _Res ->
             do_resolve_redirects(Rest, [URL | Acc])
     end.