Merge ~spitap/dkimpy:FixSilentFailNonAsync into dkimpy:master

[Adrien]

Raise an exception when calling an async function where it shouldn't.

Bug #1954331

Unmerged commits

8f008c0... by Adrien on 2022-08-04

Raise exception when calling async function where it shouldn't

diff --git a/dkim/__init__.py b/dkim/__init__.py
index acdad51..4c4ba09 100644
--- a/dkim/__init__.py
+++ b/dkim/__init__.py
@@ -39,6 +39,7 @@ import re
 import sys
 import time
 import binascii
+import inspect
 
 # only needed for arc
 try:
@@ -187,6 +188,9 @@ class NaClNotFoundError(DKIMException):
 class UnknownKeyTypeError(DKIMException):
     """ Key type (k tag) is not known (rsa/ed25519) """
 
+class AsyncFunctionCalledFromNonAsync(DKIMException):
+    """ Tried to call async function not properly"""
+
 
 def select_headers(headers, include_headers):
     """Select message header fields to be signed/verified.
@@ -946,6 +950,8 @@ class DKIM(DomainSigner):
   #: @return: True if signature verifies or False otherwise
   #: @raise DKIMException: when the message, signature, or key are badly formed
   def verify(self,idx=0,dnsfunc=get_txt):
+    if inspect.iscoroutinefunction(dnsfunc):
+        raise AsyncFunctionCalledFromNonAsync()
     prep = self.verify_headerprep(idx)
     if prep:
         sig, include_headers, sigheaders = prep