Correct signature in ARC-Seal on LF as linesep (LP: #2052720) - Thanks to Nikolay Vizovitin for the report and the fix

dkim/__init__.py

@@ -1119,14 +1119,12 @@ class ARC(DomainSigner):
 
     # Compute ARC-Authentication-Results
     aar_value = ("i=%d; " % instance).encode('utf-8') + auth_results.rstrip() + self.linesep
-
+    canon_policy = CanonicalizationPolicy.from_c_value(b'relaxed/relaxed')
     new_arc_set.append(b"ARC-Authentication-Results: " + aar_value)
-    self.headers.insert(0, (b"arc-authentication-results", aar_value))
     arc_headers.insert(0, (b"ARC-Authentication-Results", aar_value))
+    self.headers = canon_policy.canonicalize_headers(arc_headers[:1]) + self.headers
 
     # Compute bh=
-    canon_policy = CanonicalizationPolicy.from_c_value(b'relaxed/relaxed')
-
     self.hasher = HASH_ALGORITHMS[self.signature_algorithm]
     h = HashThrough(self.hasher(), self.debug_content)
     h.update(canon_policy.canonicalize_body(self.body))
@@ -1154,8 +1152,8 @@ class ARC(DomainSigner):
                           b"ARC-Message-Signature", pk, standardize)
 
     new_arc_set.append(b"ARC-Message-Signature: " + res)
-    self.headers.insert(0, (b"ARC-Message-Signature", res))
     arc_headers.insert(0, (b"ARC-Message-Signature", res))
+    self.headers = canon_policy.canonicalize_headers(arc_headers[:1]) + self.headers
 
     # Compute ARC-Seal
     as_fields = [x for x in [
@@ -1183,8 +1181,8 @@ class ARC(DomainSigner):
                            b"ARC-Seal", pk, standardize)
 
     new_arc_set.append(b"ARC-Seal: " + res)
-    self.headers.insert(0, (b"ARC-Seal", res))
     arc_headers.insert(0, (b"ARC-Seal", res))
+    self.headers = canon_policy.canonicalize_headers(arc_headers[:1]) + self.headers
 
     new_arc_set.reverse()
 

dkim/canonicalization.py

@@ -58,7 +58,7 @@ def strip_trailing_lines(content):
     return content[:end]
 
 def unfold_header_value(content):
-    return re.sub(b"\r\n", b"", content)
+    return re.sub(b"\r?\n", b"", content)
 
 
 def correct_empty_body(content):