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/websites/forms.py

@@ -15,6 +15,7 @@ from crispy_forms.layout import (
     Submit,
 )
 
+from domains.forms import relative_domain_validator
 from .models import Website
 
 
@@ -31,7 +32,10 @@ class AddWebsiteForm(forms.ModelForm):
         self.hosting_package = kwargs.pop('hostingpackage')
         self.hosting_domain = kwargs.pop('domain')
         super(AddWebsiteForm, self).__init__(*args, **kwargs)
-        if Website.objects.filter(wildcard=True).exists():
+        self.fields['subdomain'].validators.append(relative_domain_validator)
+        if Website.objects.filter(
+            wildcard=True, domain=self.hosting_domain
+        ).exists():
             self.fields['wildcard'].widget = forms.HiddenInput()
 
         self.helper = FormHelper()
@@ -54,6 +58,8 @@ class AddWebsiteForm(forms.ModelForm):
         ).exists():
             raise forms.ValidationError(
                 _('There is already a website for this subdomain'))
+        relative_domain_validator(
+            "{0}.{1}".format(data, self.hosting_domain.domain))
         return data
 
     def save(self, commit=True):