[Question] validators.domain return True on too long FQDN

Hey,
I don't know if this is really an issue, but according to RFC1035 section 2.3.4 (https://www.freesoft.org/CIE/RFC/1035/9.htm) , FQDN cannot be longer than 253 octets.
See also: https://devblogs.microsoft.com/oldnewthing/?p=7873

Idk if this is intentional but the actual behavior of validators.domain return True even if the FQDN is too long.

Step to reproduce:

Install the latest version of validators
Run the following code

a = "www.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.abcdefghijklmnop.fr"
print(len(a)) # 261
print(validators.domain(a)) # True

Expected behavior:

The method must return False

Actual behavior:

The method return True

The Microsoft blog URL you shared, mentions that it is harder to describe the length of UTF-8 characters in octets, so if I such a have condition:

if len(value) > 253:
    return False

it would work, but that's not what RFC 1035, section 3.1 means.

test: cover IDN octet length and the #407 example

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[Question] validators.domain return True on too long FQDN #407

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[Question] validators.domain return True on too long FQDN #407

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nandgator commented on Oct 19, 2024

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