Update the Register payloads to support KMIP 2.0

This change updates the Register payloads to support KMIP 2.0
features, including swapping out TemplateAttributes for the new
Attributes structure in the request payload and removing all
attribute-related encodings from the response payload. Unit tests
have been added to cover these changes.

kmip/core/messages/payloads/register.py

@@ -174,17 +174,37 @@ class RegisterRequestPayload(primitives.Struct):
                 "type."
             )
 
-        if self.is_tag_next(enums.Tags.TEMPLATE_ATTRIBUTE, local_buffer):
-            self._template_attribute = objects.TemplateAttribute()
-            self._template_attribute.read(
-                local_buffer,
-                kmip_version=kmip_version
-            )
+        if kmip_version < enums.KMIPVersion.KMIP_2_0:
+            if self.is_tag_next(enums.Tags.TEMPLATE_ATTRIBUTE, local_buffer):
+                self._template_attribute = objects.TemplateAttribute()
+                self._template_attribute.read(
+                    local_buffer,
+                    kmip_version=kmip_version
+                )
+            else:
+                raise exceptions.InvalidKmipEncoding(
+                    "The Register request payload encoding is missing the "
+                    "template attribute."
+                )
         else:
-            raise exceptions.InvalidKmipEncoding(
-                "The Register request payload encoding is missing the "
-                "template attribute."
-            )
+            # NOTE (ph) For now, leave attributes natively in TemplateAttribute
+            # form and just convert to the KMIP 2.0 Attributes form as needed
+            # for encoding/decoding purposes. Changing the payload to require
+            # the new Attributes structure will trigger a bunch of second-order
+            # effects across the client and server codebases that is beyond
+            # the scope of updating the Register payloads to support KMIP 2.0.
+            if self.is_tag_next(enums.Tags.ATTRIBUTES, local_buffer):
+                attributes = objects.Attributes()
+                attributes.read(local_buffer, kmip_version=kmip_version)
+                value = objects.convert_attributes_to_template_attribute(
+                    attributes
+                )
+                self._template_attribute = value
+            else:
+                raise exceptions.InvalidKmipEncoding(
+                    "The Register request payload encoding is missing the "
+                    "attributes structure."
+                )
 
         managed_object = self.secret_factory.create(self.object_type)
 
@@ -224,16 +244,34 @@ class RegisterRequestPayload(primitives.Struct):
                 "field."
             )
 
-        if self._template_attribute:
-            self._template_attribute.write(
-                local_buffer,
-                kmip_version=kmip_version
-            )
+        if kmip_version < enums.KMIPVersion.KMIP_2_0:
+            if self._template_attribute:
+                self._template_attribute.write(
+                    local_buffer,
+                    kmip_version=kmip_version
+                )
+            else:
+                raise exceptions.InvalidField(
+                    "The Register request payload is missing the template "
+                    "attribute field."
+                )
         else:
-            raise exceptions.InvalidField(
-                "The Register request payload is missing the template "
-                "attribute field."
-            )
+            # NOTE (ph) For now, leave attributes natively in TemplateAttribute
+            # form and just convert to the KMIP 2.0 Attributes form as needed
+            # for encoding/decoding purposes. Changing the payload to require
+            # the new Attributes structure will trigger a bunch of second-order
+            # effects across the client and server codebases that is beyond
+            # the scope of updating the Register payloads to support KMIP 2.0.
+            if self._template_attribute:
+                attributes = objects.convert_template_attribute_to_attributes(
+                    self._template_attribute
+                )
+                attributes.write(local_buffer, kmip_version=kmip_version)
+            else:
+                raise exceptions.InvalidField(
+                    "The Register request payload is missing the template "
+                    "attribute field."
+                )
 
         if self._managed_object:
             self._managed_object.write(local_buffer, kmip_version=kmip_version)
@@ -391,12 +429,13 @@ class RegisterResponsePayload(primitives.Struct):
                 "identifier."
             )
 
-        if self.is_tag_next(enums.Tags.TEMPLATE_ATTRIBUTE, local_buffer):
-            self._template_attribute = objects.TemplateAttribute()
-            self._template_attribute.read(
-                local_buffer,
-                kmip_version=kmip_version
-            )
+        if kmip_version < enums.KMIPVersion.KMIP_2_0:
+            if self.is_tag_next(enums.Tags.TEMPLATE_ATTRIBUTE, local_buffer):
+                self._template_attribute = objects.TemplateAttribute()
+                self._template_attribute.read(
+                    local_buffer,
+                    kmip_version=kmip_version
+                )
 
         self.is_oversized(local_buffer)
 
@@ -427,11 +466,12 @@ class RegisterResponsePayload(primitives.Struct):
                 "identifier field."
             )
 
-        if self._template_attribute:
-            self._template_attribute.write(
-                local_buffer,
-                kmip_version=kmip_version
-            )
+        if kmip_version < enums.KMIPVersion.KMIP_2_0:
+            if self._template_attribute:
+                self._template_attribute.write(
+                    local_buffer,
+                    kmip_version=kmip_version
+                )
 
         self.length = local_buffer.length()
         super(RegisterResponsePayload, self).write(