Address review comments

Lib/email/_policybase.py

@@ -4,6 +4,7 @@
 """
 
 import abc
+import re
 from email import header
 from email import charset as _charset
 from email.utils import _has_surrogates
@@ -14,6 +15,15 @@
     'compat32',
     ]
 
+header_re  = re.compile(r'^[^\s:]+$')
+header_ascii_re = re.compile("[\041-\071\073-\176]+$")
+
+def validate_header_name(name):
+    # Validate header name according to RFC 5322
+    if not header_re.match(name):
+        raise ValueError(f"Invalid header field name {name!r}")
+    if not header_ascii_re.match(name):
+        raise ValueError(f"Header field name contains invalid characters: {name!r}")
 
 class _PolicyBase:
 
@@ -90,14 +100,6 @@ def __add__(self, other):
         """
         return self.clone(**other.__dict__)
 
-def validate_header(name):
-    # Validate header name according to RFC 5322
-    import re
-    if not re.match(r'^[^\s:]+$', name):
-        raise ValueError(f"Invalid header field name {name!r}")
-    # Only allow printable ASCII characters
-    if any(ord(c) < 33 or ord(c) > 126 for c in name):
-        raise ValueError(f"Invalid header field name {name!r}")
 
 def _append_doc(doc, added_doc):
     doc = doc.rsplit('\n', 1)[0]
@@ -322,7 +324,7 @@ def header_store_parse(self, name, value):
         """+
         The name and value are returned unmodified.
         """
-        validate_header(name)
+        validate_header_name(name)
         return (name, value)
 
     def header_fetch_parse(self, name, value):

Lib/email/policy.py

@@ -4,7 +4,13 @@
 
 import re
 import sys
-from email._policybase import Policy, Compat32, compat32, _extend_docstrings, validate_header
+from email._policybase import (
+    _extend_docstrings,
+    Compat32,
+    compat32,
+    Policy,
+    validate_header
+)
 from email.utils import _has_surrogates
 from email.headerregistry import HeaderRegistry as HeaderRegistry
 from email.contentmanager import raw_data_manager