ensure that hmac.digest does not raise OverflowError`

Author: picnixz

Lib/hmac.py

@@ -241,19 +241,22 @@ def digest(key, msg, digest):
     if _hashopenssl and isinstance(digest, (str, _functype)):
         try:
             return _hashopenssl.hmac_digest(key, msg, digest)
-        except OverflowError as exc:
-            if (not _hmac and isinstance(digest, str)) or callable(digest):
-                # Without re-raising now, slow HMAC will be used as
-                # HACL* HMAC only identifies digests by their name.
-                raise exc
+        except OverflowError:
+            try:
+                return _hashopenssl.hmac_new(key, msg, digest).digest()
+            except _hashopenssl.UnsupportedDigestmodError:
+                pass
         except _hashopenssl.UnsupportedDigestmodError:
             pass
 
     if _hmac and isinstance(digest, str):
         try:
-            # The following call may raise an OverflowError
-            # but we do not want to fallback to slow HMAC.
             return _hmac.compute_digest(key, msg, digest)
+        except OverflowError:
+            try:
+                return _hmac.new(key, msg, digest).digest()
+            except _hmac.UnknownHashError:
+                pass
         except _hmac.UnknownHashError:
             pass
 

Lib/test/test_hmac.py

@@ -1513,8 +1513,8 @@ def test_hmac_digest_overflow_error_no_openssl(self, size):
         bigmsg = b'M' * size
 
         with unittest.mock.patch.object(hmac, "_compute_digest_fallback") as f:
-            self.assertRaises(OverflowError, hmac.digest, bigkey, b'm', "md5")
-            self.assertRaises(OverflowError, hmac.digest, b'k', bigmsg, "md5")
+            self.assertIsInstance(hmac.digest(bigkey, b'msg', "md5"), bytes)
+            self.assertIsInstance(hmac.digest(b'key', bigmsg, "md5"), bytes)
         f.assert_not_called()
 
     @hashlib_helper.requires_openssl_hashdigest("md5")
@@ -1528,8 +1528,8 @@ def test_hmac_digest_overflow_error_no_builtin(self, size):
         bigmsg = b'M' * size
 
         with unittest.mock.patch.object(hmac, "_compute_digest_fallback") as f:
-            self.assertRaises(OverflowError, hmac.digest, bigkey, b'm', "md5")
-            self.assertRaises(OverflowError, hmac.digest, b'k', bigmsg, "md5")
+            self.assertIsInstance(hmac.digest(bigkey, b'msg', "md5"), bytes)
+            self.assertIsInstance(hmac.digest(b'key', bigmsg, "md5"), bytes)
         f.assert_not_called()
 
     @hashlib_helper.requires_hashdigest("md5", openssl=True)