Merge "Allow TXT record over 255 characters if split"

designate/objects/rrdata_txt.py

@@ -26,14 +26,23 @@ class TXT(Record):
     Defined in: RFC1035
     """
     fields = {
-        'txt_data': fields.TxtField(maxLength=255)
+        'txt_data': fields.TxtField()
     }
 
     def _to_string(self):
         return self.txt_data
 
-    def _from_string(self, value):
-        if (not value.startswith('"') and not value.endswith('"')):
+    @staticmethod
+    def _is_wrapped_in_double_quotes(value):
+        return value.startswith('"') and value.endswith('"')
+
+    def _validate_record_single_string(self, value):
+        if len(value) > 255:
+            err = ("Any TXT record string exceeding "
+                   "255 characters has to be split.")
+            raise InvalidObject(err)
+
+        if not self._is_wrapped_in_double_quotes(value):
             # value with spaces should be quoted as per RFC1035 5.1
             for element in value:
                 if element.isspace():
@@ -50,6 +59,29 @@ class TXT(Record):
                                "backslash.")
                         raise InvalidObject(err)
 
+    def _from_string(self, value):
+        if len(value) > 255:
+            # expecting record containing multiple strings as
+            # per rfc7208 3.3 and rfc1035 3.3.14
+            stripped_value = value.strip('"')
+            if (not self._is_wrapped_in_double_quotes(value) and
+                    '" "' not in stripped_value):
+                err = ("TXT record strings over 255 characters "
+                       "have to be split into multiple strings "
+                       "wrapped in double quotes.")
+                raise InvalidObject(err)
+
+            record_strings = stripped_value.split('" "')
+            for record_string in record_strings:
+                # add back the delimiting quotes after
+                # strip and split for each string
+                record_string = '"{}"'.format(record_string)
+                # further validate each string individually
+                self._validate_record_single_string(value=record_string)
+        else:
+            # validate single TXT record string
+            self._validate_record_single_string(value=value)
+
         self.txt_data = value
 
     # The record type is defined in the RFC. This will be used when the record

designate/tests/test_api/test_v2/test_recordsets.py

@@ -567,6 +567,17 @@ class ApiV2RecordSetsTest(ApiV2TestCase):
         self._assert_exception('invalid_object', 400,
                                self.client.put_json, url, body)
 
+    def test_create_txt_record_multiple_strings(self):
+        # create TXT record with string split in 2
+        new_zone = self.create_zone(name='example.net.')
+        recordset = self.create_recordset(new_zone, 'TXT')
+        self.create_record(new_zone, recordset)
+        record = '"{}" "{}"'.format('a' * 250, 'a' * 250)
+        body = {'description': 'Tester', 'records': [record]}
+        url = '/zones/%s/recordsets/%s' % (recordset['zone_id'],
+                                           recordset['id'])
+        self.client.put_json(url, body, status=202)
+
     def test_update_recordset_with_record_clear(self):
         # Create a recordset with one record
         recordset = self.create_recordset(self.zone, 'A')

designate/tests/unit/objects/test_rrdata_txt.py

@@ -34,3 +34,13 @@ class RRDataTXTTest(oslotest.base.BaseTestCase):
             'Provided object does not match schema',
             record.validate
         )
+
+    def test_multiple_strings_one_record(self):
+        # these quotes do not have to be escaped as
+        # per rfc7208 3.3 and rfc1035 3.3.14
+        record = objects.TXT(data='"foo" "bar"')
+        self.assertRaisesRegex(
+            exceptions.InvalidObject,
+            'Provided object does not match schema',
+            record.validate
+        )

doc/source/user/manage-recordsets.rst

@@ -149,6 +149,22 @@ because it is the default:
         $ dig @ns1.example.net www.example.org. +short
         192.0.2.1
 
+If you want to construct a ``TXT`` record that exceeds the 255-octet
+maximum length of a character-string, it has to be split into
+multiple strings as defined in RFC7208 section 3.3. For example,
+``"v=DKIM1; .... firstsecond string..."`` can become
+``"v=DKIM1; .... first" "second string..."``. If you provide a record
+data with less than 255 characters, it will be treated as a
+single character-string and validated for empty spaces outside quotes
+and unescaped double quotation marks as in RFC1035 section 5.1.
+
+For example, to create a ``TXT`` record made of one string of 410
+characters you can split it into 2 to like this:
+
+   .. code-block:: console
+
+      $ openstack recordset create --type TXT --record '"210 characters string" "200 characters string"' example.org. _domainkey
+
 Updating a recordset
 --------------------