[damned-lies] Use HTTP_X_FORWARDED_FOR header when available

[Claude Paroz <claudep src gnome org>]

commit 1dcac133debf853e53171fadabfb9bf0cf4601c5
Author: Claude Paroz <claude 2xlibre net>
Date:   Tue Sep 17 08:42:49 2019 +0200

    Use HTTP_X_FORWARDED_FOR header when available

 common/utils.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/common/utils.py b/common/utils.py
index eead3f6f..638fb6dd 100644
--- a/common/utils.py
+++ b/common/utils.py
@@ -97,7 +97,11 @@ def send_mail(subject, message, **kwargs):
 
 
 def check_gitlab_request(request):
-    from_host = socket.gethostbyaddr(request.META.get('REMOTE_ADDR'))[0]
+    remote_ip = request.META.get('HTTP_X_FORWARDED_FOR', request.META.get('REMOTE_ADDR'))
+    try:
+        from_host = socket.gethostbyaddr(remote_ip)[0]
+    except socket.herror:
+        return False
     return (
         request.method == 'POST' and (
             from_host == 'gitlab.gnome.org' or (