fix(api): disallow generic type format like TYPExxx

pdns would convert types like TYPE99 to the named ones (here: SPF),
but our API cannot do so without maintaining a mapping table that
depends on the pdns version. Currently, we would store two distinct
RRsets in our API database, corresponding to only one RRset in pdns.
Worse, if one RRset was deleted (along with the one on pdns), the
other would remain as an orphan.

The only usecase for this would be new types quickly gaining
popularity although pdns does not know them yet. In this case, we
can address the issue again.

api/desecapi/serializers.py

@@ -167,6 +167,9 @@ def validate_type(self, value):
         if value in RRset.RESTRICTED_TYPES:
             raise serializers.ValidationError(
                 "You cannot tinker with the %s RRset." % value)
+        if value.startswith('TYPE'):
+            raise serializers.ValidationError(
+                "Generic type format is not supported.")
         return value
 
     def to_representation(self, instance):

test/e2e/spec/api_spec.js

@@ -306,6 +306,7 @@ describe("API", function () {
                                 {'subname': 'd.1', 'ttl': 50, 'type': 'AAAA'},
                                 {'subname': 'd.1', 'ttl': 50, 'type': 'SOA', 'records': ['ns1.desec.io. peter.desec.io. 2018034419 10800 3600 604800 60']},
                                 {'subname': 'd.1', 'ttl': 50, 'type': 'OPT', 'records': ['9999']},
+                                {'subname': 'd.1', 'ttl': 50, 'type': 'TYPE099', 'records': ['v=spf1 mx -all']},
                             ]
                         );
                         expect(response).to.have.status(400);
@@ -317,6 +318,7 @@ describe("API", function () {
                             { records: [ 'This field is required.' ] },
                             { type: [ 'You cannot tinker with the SOA RRset.' ] },
                             { type: [ 'You cannot tinker with the OPT RRset.' ] },
+                            { type: [ 'Generic type format is not supported.' ] },
                         ]);
 
                         return chakram.wait();