implement domain name validation

- implement domains.forms.relative_domain_validator
- use the validator for domain field validation in
  domains.forms.CreateHostingDomainForm
- use the validator for subdomain field validation in
  websites.forms.AddWebsiteForm

gnuviechadmin/domains/forms.py

@@ -4,6 +4,8 @@ This module defines form classes for domain editing.
 """
 from __future__ import absolute_import, unicode_literals
 
+import re
+
 from django import forms
 from django.core.urlresolvers import reverse
 from django.utils.translation import ugettext as _
@@ -17,6 +19,18 @@ from crispy_forms.layout import (
 from .models import HostingDomain
 
 
+def relative_domain_validator(value):
+    """
+    This validator ensures that the given value is a valid lowercase
+    """
+    if len(value) > 254:
+        raise forms.ValidationError(
+            _('host name too long'), code='too-long')
+    allowed = re.compile(r"(?!-)[a-z\d-]{1,63}(?<!-)$")
+    if not all(allowed.match(x) for x in value.split('.')):
+        raise forms.ValidationError(_('invalid domain name'))
+
+
 class CreateHostingDomainForm(forms.ModelForm):
     """
     This form is used to create new HostingDomain instances.
@@ -29,6 +43,7 @@ class CreateHostingDomainForm(forms.ModelForm):
     def __init__(self, instance, *args, **kwargs):
         self.hosting_package = kwargs.pop('hostingpackage')
         super(CreateHostingDomainForm, self).__init__(*args, **kwargs)
+        self.fields['domain'].validators.append(relative_domain_validator)
         self.helper = FormHelper()
         self.helper.form_action = reverse(
             'create_hosting_domain', kwargs={