Description of problem:
From https://bugzilla.redhat.com/show_bug.cgi?id=817413#c3 a component in a
zone name cannot be longer than 63 chars.

Tried adding using command:
# ipa dnszone-add  domain.sixthreemax.12345678901234567890123345678901234567890
123456789012345678901234567890.com

Got error:
ipa: ERROR: non-public: UnicodeError: label empty or too long
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/ipalib/backend.py", line 129, in
execute
    result = self.Command[_name](*args, **options)
  File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 431, in
__call__
    params.update(self.get_default(**params))
  File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 657, in
get_default
    return dict(self.__get_default_iter(params, kw))
  File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 686, in
__get_default_iter
    kw[param.name] = param(kw[param.name], **kw)
  File "/usr/lib/python2.7/site-packages/ipalib/parameters.py", line 565, in
__call__
    value = self.convert(self.normalize(value))
  File "/usr/lib/python2.7/site-packages/ipalib/parameters.py", line 797, in
convert
    return self._convert_scalar(value)
  File "/usr/lib/python2.7/site-packages/ipalib/parameters.py", line 1953, in
_convert_scalar
    domain_name = DNSName(value)
  File "/usr/lib/python2.7/site-packages/ipapython/dnsutil.py", line 34, in
__init__
    labels = dns.name.from_unicode(labels, origin).labels
  File "/usr/lib/python2.7/site-packages/dns/name.py", line 590, in
from_unicode
    labels.append(encodings.idna.ToASCII(label))
  File "/usr/lib64/python2.7/encodings/idna.py", line 73, in ToASCII
    raise UnicodeError("label empty or too long")
UnicodeError: label empty or too long
ipa: ERROR: an internal error has occurred




Version-Release number of selected component (if applicable):
ipa-server-4.1.0-6.el7.x86_64
bind-dyndb-ldap-6.0-1.el7.x86_64


How reproducible:
always

Steps to Reproduce:
1. Add a zone with long name
# ipa dnszone-add  domain.sixthreemax.12345678901234567890123345678901234567890
123456789012345678901234567890.com


Actual results:
Got traceback as above


Expected results:
Should fail gracefully, and not allow this zone to be added


Additional info: