Fix URLField to allow numbers in top level domain

Add a custom regex to URLField that allows numbers to be present in the
top level domain, e.g. https://towerhost.org42

Set by variable allow_numbers_in_top_level_domain in URLField __init__,
and is set to True by default. If set to False, it will use the regex
specified in the built-in django URLValidator class.

This solution was originally implemented in LDAPServerURIField, but is
now implemented in URLField to support this behavior more generally. The
changes in LDAPServerURIField are longer needed and have been removed in
this commit.

Adds unit testing to make sure URLField changes handle regex input
and settings correctly.

awx/conf/fields.py

@@ -1,11 +1,12 @@
 # Python
 import os
+import re
 import logging
 import urllib.parse as urlparse
 from collections import OrderedDict
 
 # Django
-from django.core.validators import URLValidator
+from django.core.validators import URLValidator, _lazy_re_compile
 from django.utils.translation import ugettext_lazy as _
 
 # Django REST Framework
@@ -118,17 +119,42 @@ class StringListPathField(StringListField):
 
 
 class URLField(CharField):
+    # these lines set up a custom regex that allow numbers in the
+    # top-level domain
+    tld_re = (
+        r'\.'                                              # dot
+        r'(?!-)'                                           # can't start with a dash
+        r'(?:[a-z' + URLValidator.ul + r'0-9' + '-]{2,63}' # domain label, this line was changed from the original URLValidator
+        r'|xn--[a-z0-9]{1,59})'                            # or punycode label
+        r'(?<!-)'                                          # can't end with a dash
+        r'\.?'                                             # may have a trailing dot
+    )
+
+    host_re = '(' + URLValidator.hostname_re + URLValidator.domain_re + tld_re + '|localhost)'
+
+    regex = _lazy_re_compile(
+        r'^(?:[a-z0-9\.\-\+]*)://'  # scheme is validated separately
+        r'(?:[^\s:@/]+(?::[^\s:@/]*)?@)?'  # user:pass authentication
+        r'(?:' + URLValidator.ipv4_re + '|' + URLValidator.ipv6_re + '|' + host_re + ')'
+        r'(?::\d{2,5})?'  # port
+        r'(?:[/?#][^\s]*)?'  # resource path
+        r'\Z', re.IGNORECASE)
 
     def __init__(self, **kwargs):
         schemes = kwargs.pop('schemes', None)
         regex = kwargs.pop('regex', None)
         self.allow_plain_hostname = kwargs.pop('allow_plain_hostname', False)
+        self.allow_numbers_in_top_level_domain = kwargs.pop('allow_numbers_in_top_level_domain', True)
         super(URLField, self).__init__(**kwargs)
         validator_kwargs = dict(message=_('Enter a valid URL'))
         if schemes is not None:
             validator_kwargs['schemes'] = schemes
         if regex is not None:
             validator_kwargs['regex'] = regex
+        if self.allow_numbers_in_top_level_domain and regex is None:
+            # default behavior is to allow numbers in the top level domain
+            # if a custom regex isn't provided
+            validator_kwargs['regex'] = URLField.regex
         self.validators.append(URLValidator(**validator_kwargs))
 
     def to_representation(self, value):