Save order of elements for Diaspora relayables to the entities

Refs: diaspora/diaspora_federation#26

CHANGELOG.md

@@ -19,6 +19,7 @@ Additionally, Diaspora entity mappers `message_to_objects` and `element_to_objec
     * Add source payload object to the entity at `_source_object` when processing it.
     * Add sender public key to the entity at `_sender_key`, but only if it was used for validating signatures.
 * Add support for the new Diaspora payload properties coming in the next protocol version. Old XML payloads are and will be still supported.
+* `DiasporaComment` and `DiasporaLike` will get the order of elements in the XML payload as a list in `xml_tags`. For implementers who want to recreate payloads for these relayables, this list should be saved for later use.
 
 ### Changed
 * Refactor processing of Diaspora payload XML into entities. Diaspora protocol is dropping the `<XML><post></post></XML>` wrapper for the payloads. Payloads with the wrapper will still be parsed as before.

federation/entities/diaspora/entities.py

@@ -32,6 +32,7 @@ class DiasporaEntityMixin(BaseEntity):
 
 
 class DiasporaRelayableMixin(DiasporaEntityMixin):
+    _xml_tags = []
     parent_signature = ""
 
     def __init__(self, *args, **kwargs):

federation/entities/diaspora/mappers.py

@@ -7,6 +7,7 @@ from federation.entities.base import Image, Relationship, Post, Reaction, Commen
 from federation.entities.diaspora.entities import (
     DiasporaPost, DiasporaComment, DiasporaLike, DiasporaRequest, DiasporaProfile, DiasporaRetraction,
     DiasporaRelayableMixin)
+from federation.protocols.diaspora.signatures import get_element_child_info
 from federation.utils.diaspora import retrieve_and_parse_profile
 
 logger = logging.getLogger("federation")
@@ -74,6 +75,7 @@ def element_to_objects(element, sender_key_fetcher=None):
     entity._source_object = element
     # If relayable, fetch sender key for validation
     if issubclass(cls, DiasporaRelayableMixin):
+        entity._xml_tags = get_element_child_info(element, "tag")
         if sender_key_fetcher:
             entity._sender_key = sender_key_fetcher(entity.handle)
         else:
@@ -124,7 +126,7 @@ def message_to_objects(message, sender_key_fetcher=None):
 
 def transform_attributes(attrs, cls):
     """Transform some attribute keys.
-    
+
     :param attrs: Properties from the XML
     :type attrs: dict
     :param cls: Class of the entity

federation/protocols/diaspora/signatures.py

@@ -5,11 +5,23 @@ from Crypto.PublicKey import RSA
 from Crypto.Signature import PKCS1_v1_5
 
 
-def _create_signature_hash(doc):
+def get_element_child_info(doc, attr):
+    """Get information from child elements of this elementas a list since order is important.
+
+    Don't include signature tags.
+
+    :param doc: XML element
+    :param attr: Attribute to get from the elements, for example "tag" or "text".
+    """
     props = []
     for child in doc:
         if child.tag not in ["author_signature", "parent_author_signature"]:
-            props.append(child.text)
+            props.append(getattr(child, attr))
+    return props
+
+
+def _create_signature_hash(doc):
+    props = get_element_child_info(doc, "text")
     content = ";".join(props)
     return SHA256.new(content.encode("ascii"))
 

federation/tests/entities/diaspora/test_mappers.py

@@ -47,7 +47,7 @@ class TestDiasporaEntityMappersReceive():
         assert post.raw_content == "((status message))"
         assert post.guid == "((guidguidguidguidguidguidguid))"
         assert post.handle == "alice@alice.diaspora.example.org"
-        assert post.public == False
+        assert post.public is False
         assert post.created_at == datetime(2011, 7, 20, 1, 36, 7)
         assert post.provider_display_name == "Socialhome"
 
@@ -88,6 +88,9 @@ class TestDiasporaEntityMappersReceive():
         assert comment.participation == "comment"
         assert comment.raw_content == "((text))"
         assert comment.signature == "((signature))"
+        assert comment._xml_tags == [
+            "guid", "parent_guid", "text", "author",
+        ]
         mock_validate.assert_called_once_with()
 
     @patch("federation.entities.diaspora.mappers.DiasporaLike._validate_signatures")
@@ -103,6 +106,9 @@ class TestDiasporaEntityMappersReceive():
         assert like.participation == "reaction"
         assert like.reaction == "like"
         assert like.signature == "((signature))"
+        assert like._xml_tags == [
+            "parent_type", "guid", "parent_guid", "positive", "author",
+        ]
         mock_validate.assert_called_once_with()
 
     def test_message_to_objects_request(self):