Added validation for the admin forms.

Especially the validation of the key should be helpful, as it prevents users to
store wrongly formatted keys.

binder/admin.py

@@ -1,11 +1,38 @@
+import binascii
+import dns.tsigkeyring
 from models import BindServer, Key
 from django.contrib import admin
+from django.forms import ModelForm, ValidationError
+
+class BindServerAdminForm(ModelForm):
+    def clean_statistics_port(self):
+        port = self.cleaned_data["statistics_port"]
+        if port < 1 or port > 65535:
+            raise ValidationError("Invalid port number %(port)s. Please enter "
+                                  "a valid one between 1 and 65535.",
+                                  params={'port': port})
+        return self.cleaned_data["statistics_port"]
+
 
 class BindServerAdmin(admin.ModelAdmin):
-    list_display = [ 'hostname',  'statistics_port', 'default_transfer_key' ]
+    form = BindServerAdminForm
+    list_display = ['hostname', 'statistics_port', 'default_transfer_key']
+
+
+class KeyAdminForm(ModelForm):
+    def clean_data(self):
+        try:
+            keyring = dns.tsigkeyring.from_text({'': self.cleaned_data["data"]})
+        except binascii.Error as err:
+            raise ValidationError("Invalid key data: %(error)s",
+                                  params={'error': err})
+        return self.cleaned_data["data"]
+
 
 class KeyAdmin(admin.ModelAdmin):
-    list_display = [ 'name', 'data', 'algorithm' ]
+    form = KeyAdminForm
+    list_display = ['name', 'data', 'algorithm']
+
 
 admin.site.register(BindServer, BindServerAdmin)
 admin.site.register(Key, KeyAdmin)