Check the volume metadata value is a string or not

When creating or updating the metadata for a volume, if user
give a nested value, cinder-api will raise a 500 error, the root
cause is a syntax error in sql statement.

According to cinder api ref [1], the metadata value should be a
string.

[1] https://developer.openstack.org/api-ref/block-storage/v3/?expanded=update-a-volume-s-metadata-detail#update-a-volume-s-metadata

Change-Id: I6febfe177fb49372bb6413d3b6478cb762170b2a
Closes-Bug: #1690363

cinder/tests/unit/test_utils.py

@@ -1494,3 +1494,20 @@ class TestLogLevels(test.TestCase):
         utils.set_log_levels(prefix, 'debug')
         levels = utils.get_log_levels(prefix)
         self.assertEqual('DEBUG', levels[prefix])
+
+
+@ddt.ddt
+class TestCheckMetadataProperties(test.TestCase):
+    @ddt.data(
+        {'a': {'foo': 'bar'}},  # value is a nested dict
+        {'a': 123},  # value is an integer
+        {'a': 123.4},  # value is a float
+        {'a': True},  # value is a bool
+        {'a': ('foo', 'bar')},  # value is a tuple
+        {'a': []},  # value is a list
+        {'a': None}  # value is None
+    )
+    def test_metadata_value_not_string_raise(self, meta):
+        self.assertRaises(exception.InvalidVolumeMetadata,
+                          utils.check_metadata_properties,
+                          meta)

cinder/utils.py

@@ -165,22 +165,19 @@ def check_metadata_properties(metadata=None):
         metadata = {}
 
     for k, v in metadata.items():
-        if len(k) == 0:
-            msg = _("Metadata property key blank.")
-            LOG.debug(msg)
-            raise exception.InvalidVolumeMetadata(reason=msg)
+        try:
+            check_string_length(k, "Metadata key: %s" % k, min_length=1)
+            check_string_length(v, "Value for metadata key: %s" % k)
+        except exception.InvalidInput as exc:
+            raise exception.InvalidVolumeMetadata(reason=exc)
+        # for backward compatibility
         if len(k) > 255:
             msg = _("Metadata property key %s greater than 255 "
                     "characters.") % k
-            LOG.debug(msg)
             raise exception.InvalidVolumeMetadataSize(reason=msg)
-        if v is None:
-            msg = _("Metadata property key '%s' value is None.") % k
-            raise exception.InvalidVolumeMetadata(reason=msg)
         if len(v) > 255:
             msg = _("Metadata property key %s value greater than "
                     "255 characters.") % k
-            LOG.debug(msg)
             raise exception.InvalidVolumeMetadataSize(reason=msg)