Simple checks for instance user data.

Check that instance user data wont be truncated, and that it is
valid base64 data. This partially resolves bug 1035055. I don't
love the hard coded maximum length, but I haven't worked out how
to get sqlalchemy to tell me the maximum size of the data type.

Change-Id: I045d6b4481563d01cae371cf61a91781cfed6f4b

nova/compute/api.py

@@ -21,6 +21,7 @@
 """Handles all requests relating to compute resources (e.g. guest VMs,
 networking and storage of VMs, and compute hosts on which they run)."""
 
+import base64
 import functools
 import re
 import string
@@ -58,6 +59,7 @@ LOG = logging.getLogger(__name__)
 FLAGS = flags.FLAGS
 flags.DECLARE('consoleauth_topic', 'nova.consoleauth')
 
+MAX_USERDATA_SIZE = 65535
 QUOTAS = quota.QUOTAS
 
 
@@ -473,6 +475,19 @@ class API(base.Base):
             'architecture': architecture,
             'progress': 0}
 
+        if user_data:
+            l = len(user_data)
+            if l > MAX_USERDATA_SIZE:
+                # NOTE(mikal): user_data is stored in a text column, and the
+                # database might silently truncate if its over length.
+                raise exception.InstanceUserDataTooLarge(
+                    length=l, maxsize=MAX_USERDATA_SIZE)
+
+            try:
+                base64.decodestring(user_data)
+            except base64.binascii.Error:
+                raise exception.InstanceUserDataMalformed()
+
         options_from_image = self._inherit_properties_from_image(
                 image, auto_disk_config)
 

nova/exception.py

@@ -1155,6 +1155,16 @@ class ConfigDriveUnknownFormat(NovaException):
                 "iso9660 or vfat.")
 
 
+class InstanceUserDataTooLarge(NovaException):
+    message = _("User data too large. User data must be no larger than "
+                "%(maxsize)s bytes once base64 encoded. Your data is "
+                "%(length)d bytes")
+
+
+class InstanceUserDataMalformed(NovaException):
+    message = _("User data needs to be valid base 64.")
+
+
 def get_context_from_function_and_args(function, args, kwargs):
     """Find an arg of type RequestContext and return it.
 

nova/tests/compute/test_compute.py

@@ -18,6 +18,7 @@
 #    under the License.
 """Tests for compute service"""
 
+import base64
 import copy
 import datetime
 import functools
@@ -2364,6 +2365,54 @@ class ComputeAPITestCase(BaseTestCase):
         self.assertEqual(pre_build_len,
                          len(db.instance_get_all(context.get_admin_context())))
 
+    def test_create_with_large_user_data(self):
+        """Test an instance type with too much user data."""
+
+        inst_type = instance_types.get_default_instance_type()
+
+        def fake_show(*args):
+            img = copy.copy(self.fake_image)
+            img['min_ram'] = 2
+            return img
+        self.stubs.Set(fake_image._FakeImageService, 'show', fake_show)
+
+        self.assertRaises(exception.InstanceUserDataTooLarge,
+            self.compute_api.create, self.context, inst_type, None,
+                          user_data=('1' * 65536))
+
+    def test_create_with_malformed_user_data(self):
+        """Test an instance type with malformed user data."""
+
+        inst_type = instance_types.get_default_instance_type()
+
+        def fake_show(*args):
+            img = copy.copy(self.fake_image)
+            img['min_ram'] = 2
+            return img
+        self.stubs.Set(fake_image._FakeImageService, 'show', fake_show)
+
+        self.assertRaises(exception.InstanceUserDataMalformed,
+            self.compute_api.create, self.context, inst_type, None,
+                          user_data='banana')
+
+    def test_create_with_base64_user_data(self):
+        """Test an instance type with ok much user data."""
+
+        inst_type = instance_types.get_default_instance_type()
+
+        def fake_show(*args):
+            img = copy.copy(self.fake_image)
+            img['min_ram'] = 2
+            return img
+        self.stubs.Set(fake_image._FakeImageService, 'show', fake_show)
+
+        # NOTE(mikal): a string of length 48510 encodes to 65532 characters of
+        # base64
+        (refs, resv_id) = self.compute_api.create(
+            self.context, inst_type, None,
+            user_data=base64.encodestring('1' * 48510))
+        db.instance_destroy(self.context, refs[0]['uuid'])
+
     def test_default_hostname_generator(self):
         fake_uuids = [str(utils.gen_uuid()) for x in xrange(4)]