Remove SignedMixin in favour of base entity signing by default

While the signing methods are empty at the moment, preparation for ActivityPub, where every object would need to be signed separately (as signature is not in payload header but in the object itself), get rid of separate SignedMixin and just have signature and sign() on the base entity. Diaspora entities provide the necessary methods for signing and validation for DiasporaComment currently.

federation/entities/base.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 import datetime
 import warnings
 
@@ -16,6 +15,8 @@ class BaseEntity(object):
     _allowed_children = ()
     _source_protocol = ""
     _source_object = None
+    _sender_key = ""
+    signature = ""
 
     def __init__(self, *args, **kwargs):
         self._required = []
@@ -89,6 +90,10 @@ class BaseEntity(object):
         """Override in subclasses where necessary"""
         pass
 
+    def sign(self, private_key):
+        """Implement in subclasses."""
+        pass
+
 
 class GUIDMixin(BaseEntity):
     guid = ""
@@ -167,23 +172,6 @@ class OptionalRawContentMixin(RawContentMixin):
         self._required.remove("raw_content")
 
 
-class SignedMixin(BaseEntity):
-    """Adds a signature string or object (depending on protocol).
-    
-    This will be needed to for example when relaying content.
-    """
-    _sender_key = ""
-    signature = ""
-
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self._required += ["signature"]
-
-    def sign(self, private_key):
-        """Implement in subclasses."""
-        pass
-
-
 class Image(GUIDMixin, HandleMixin, PublicMixin, OptionalRawContentMixin, CreatedAtMixin, BaseEntity):
     """Reflects a single image, possibly linked to another object."""
     remote_path = ""
@@ -225,14 +213,14 @@ class ParticipationMixin(TargetGUIDMixin):
             ))
 
 
-class Comment(RawContentMixin, GUIDMixin, ParticipationMixin, CreatedAtMixin, HandleMixin, SignedMixin):
+class Comment(RawContentMixin, GUIDMixin, ParticipationMixin, CreatedAtMixin, HandleMixin):
     """Represents a comment, linked to another object."""
     participation = "comment"
 
     _allowed_children = (Image,)
 
 
-class Reaction(GUIDMixin, ParticipationMixin, CreatedAtMixin, HandleMixin, SignedMixin):
+class Reaction(GUIDMixin, ParticipationMixin, CreatedAtMixin, HandleMixin):
     """Represents a reaction to another object, for example a like."""
     participation = "reaction"
     reaction = ""

federation/entities/diaspora/entities.py

@@ -1,6 +1,6 @@
 from lxml import etree
 
-from federation.entities.base import Comment, Post, Reaction, Relationship, Profile, Retraction, BaseEntity, SignedMixin
+from federation.entities.base import Comment, Post, Reaction, Relationship, Profile, Retraction, BaseEntity
 from federation.entities.diaspora.utils import format_dt, struct_to_xml, get_base_attributes
 from federation.exceptions import SignatureVerificationError
 from federation.protocols.diaspora.signatures import verify_relayable_signature, create_relayable_signature
@@ -31,7 +31,11 @@ class DiasporaEntityMixin(BaseEntity):
         return attributes
 
 
-class DiasporaRelayableMixin(SignedMixin, DiasporaEntityMixin):
+class DiasporaRelayableMixin(DiasporaEntityMixin):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._required += ["signature"]
+
     def _validate_signatures(self):
         super()._validate_signatures()
         if not self._sender_key:

federation/entities/diaspora/mappers.py

@@ -1,12 +1,12 @@
-# -*- coding: utf-8 -*-
 import logging
 from datetime import datetime
 
 from lxml import etree
 
-from federation.entities.base import Image, Relationship, Post, Reaction, Comment, Profile, Retraction, SignedMixin
+from federation.entities.base import Image, Relationship, Post, Reaction, Comment, Profile, Retraction
 from federation.entities.diaspora.entities import (
-    DiasporaPost, DiasporaComment, DiasporaLike, DiasporaRequest, DiasporaProfile, DiasporaRetraction)
+    DiasporaPost, DiasporaComment, DiasporaLike, DiasporaRequest, DiasporaProfile, DiasporaRetraction,
+    DiasporaRelayableMixin)
 from federation.utils.diaspora import retrieve_and_parse_profile
 
 logger = logging.getLogger("federation")
@@ -66,8 +66,8 @@ def element_to_objects(tree, sender_key_fetcher=None):
         entity._source_protocol = "diaspora"
         # Save element object to entity for possible later use
         entity._source_object = element
-        # If signable, fetch sender key
-        if issubclass(cls, SignedMixin):
+        # If relayable, fetch sender key for validation
+        if issubclass(cls, DiasporaRelayableMixin):
             if sender_key_fetcher:
                 entity._sender_key = sender_key_fetcher(entity.handle)
             else:
@@ -204,6 +204,6 @@ def get_outbound_entity(entity, private_key):
         outbound = DiasporaRetraction.from_base(entity)
     if not outbound:
         raise ValueError("Don't know how to convert this base entity to Diaspora protocol entities.")
-    if issubclass(cls, SignedMixin):
+    if issubclass(cls, DiasporaRelayableMixin):
         outbound.sign(private_key)
     return outbound

federation/tests/entities/diaspora/test_utils.py

@@ -13,7 +13,8 @@ class TestGetBaseAttributes():
         entity = Post()
         attrs = get_base_attributes(entity).keys()
         assert set(attrs) == {
-            'created_at', 'guid', 'handle', 'location', 'photos', 'provider_display_name', 'public', 'raw_content'
+            "created_at", "guid", "handle", "location", "photos", "provider_display_name", "public", "raw_content",
+            "signature",
         }
 
 

federation/tests/entities/test_base.py

@@ -4,7 +4,6 @@ import pytest
 
 from federation.entities.base import (
     BaseEntity, Relationship, Profile, RawContentMixin, GUIDMixin, HandleMixin, PublicMixin, Image, Retraction,
-    SignedMixin,
 )
 from federation.tests.factories.entities import TaggedPostFactory, PostFactory
 
@@ -70,15 +69,6 @@ class TestPublicMixinValidate():
             public.validate()
 
 
-class TestSignedMixinValidate():
-    def test_required_validates(self):
-        signed = SignedMixin()
-        with pytest.raises(ValueError):
-            signed.validate()
-        signed.signature = "foobar"
-        signed.validate()
-
-
 class TestEntityRequiredAttributes():
     def test_entity_checks_for_required_attributes(self):
         entity = BaseEntity()