providers/saml: handle uncompressed SAML AuthNRequest

passbook/providers/saml/processors/base.py

@@ -159,8 +159,9 @@ class Processor:
         request_acs_url = self._request_params["ACS_URL"]
 
         if self._remote.acs_url != request_acs_url:
-            msg = "couldn't find ACS url '{}' in SAML2IDP_REMOTES " "setting.".format(
-                request_acs_url
+            msg = (
+                f"ACS URL of {request_acs_url} doesn't match Provider "
+                f"ACS URL of {self._remote.acs_url}."
             )
             self._logger.info(msg)
             raise CannotHandleAssertion(msg)

passbook/providers/saml/utils/encoding.py

@@ -6,7 +6,10 @@ import zlib
 def decode_base64_and_inflate(b64string):
     """Base64 decode and ZLib decompress b64string"""
     decoded_data = base64.b64decode(b64string)
-    return zlib.decompress(decoded_data, -15)
+    try:
+        return zlib.decompress(decoded_data, -15)
+    except zlib.error:
+        return decoded_data
 
 
 def deflate_and_base64_encode(string_val):