dmarcpipe.py: Fix potential for RecursionError in octet_streamHEADmaster

If an attachment of mime type 'application/octet-stream' is recognised
as 'application/octet-stream' then the program would enter into an
infinite loop and throw a RecursionError which likely wouldn't be too
bad but it's probably clearer to give a KeyError and mark the report
as invalid instead.

1 files changed, 6 insertions, 1 deletions

diff --git a/dmarcpipe.py b/dmarcpipe.py
index bbcc914..0178a1e 100755
--- a/dmarcpipe.py
+++ b/dmarcpipe.py
@@ -47,7 +47,12 @@ def zip2xml(data):
     return z.open(n[0]).read()
 
 gzip2xml = lambda data: gz_decompress(data)
-octet_stream = lambda data: decode(data, magic(data).mime_type)
+
+def octet_stream(data):
+    mime = magic(data).mime_type
+    if mime == 'application/octet-stream':
+        raise KeyError
+    return decode(data, mime)
 
 decoders = {
         'application/gzip': gzip2xml,