""" activitypub model functionality """ from base64 import b64encode from collections import namedtuple from functools import reduce import json import operator import logging from uuid import uuid4 import requests from requests.exceptions import RequestException from Crypto.PublicKey import RSA from Crypto.Signature import pkcs1_15 from Crypto.Hash import SHA256 from django.apps import apps from django.core.paginator import Paginator from django.db.models import Q from django.utils.http import http_date from bookwyrm import activitypub from bookwyrm.settings import USER_AGENT, PAGE_LENGTH from bookwyrm.signatures import make_signature, make_digest from bookwyrm.tasks import app from bookwyrm.models.fields import ImageField, ManyToManyField logger = logging.getLogger(__name__) # I tried to separate these classes into mutliple files but I kept getting # circular import errors so I gave up. I'm sure it could be done though! PropertyField = namedtuple("PropertyField", ("set_activity_from_field")) # pylint: disable=invalid-name def set_activity_from_property_field(activity, obj, field): """assign a model property value to the activity json""" activity[field[1]] = getattr(obj, field[0]) class ActivitypubMixin: """add this mixin for models that are AP serializable""" activity_serializer = lambda: {} reverse_unfurl = False def __init__(self, *args, **kwargs): """collect some info on model fields for later use""" self.image_fields = [] self.many_to_many_fields = [] self.simple_fields = [] # "simple" # sort model fields by type for field in self._meta.get_fields(): if not hasattr(field, "field_to_activity"): continue if isinstance(field, ImageField): self.image_fields.append(field) elif isinstance(field, ManyToManyField): self.many_to_many_fields.append(field) else: self.simple_fields.append(field) # a list of allll the serializable fields self.activity_fields = ( self.image_fields + self.many_to_many_fields + self.simple_fields ) if hasattr(self, "property_fields"): self.activity_fields += [ # pylint: disable=cell-var-from-loop PropertyField(lambda a, o: set_activity_from_property_field(a, o, f)) for f in self.property_fields ] # these are separate to avoid infinite recursion issues self.deserialize_reverse_fields = ( self.deserialize_reverse_fields if hasattr(self, "deserialize_reverse_fields") else [] ) self.serialize_reverse_fields = ( self.serialize_reverse_fields if hasattr(self, "serialize_reverse_fields") else [] ) super().__init__(*args, **kwargs) @classmethod def find_existing_by_remote_id(cls, remote_id): """look up a remote id in the db""" return cls.find_existing({"id": remote_id}) @classmethod def find_existing(cls, data): """compare data to fields that can be used for deduplation. This always includes remote_id, but can also be unique identifiers like an isbn for an edition""" filters = [] # grabs all the data from the model to create django queryset filters for field in cls._meta.get_fields(): if ( not hasattr(field, "deduplication_field") or not field.deduplication_field ): continue value = data.get(field.get_activitypub_field()) if not value: continue filters.append({field.name: value}) if hasattr(cls, "origin_id") and "id" in data: # kinda janky, but this handles special case for books filters.append({"origin_id": data["id"]}) if not filters: # if there are no deduplication fields, it will match the first # item no matter what. this shouldn't happen but just in case. return None objects = cls.objects if hasattr(objects, "select_subclasses"): objects = objects.select_subclasses() # an OR operation on all the match fields, sorry for the dense syntax match = objects.filter(reduce(operator.or_, (Q(**f) for f in filters))) # there OUGHT to be only one match return match.first() def broadcast(self, activity, sender, software=None): """send out an activity""" broadcast_task.delay( sender.id, json.dumps(activity, cls=activitypub.ActivityEncoder), self.get_recipients(software=software), ) def get_recipients(self, software=None): """figure out which inbox urls to post to""" # first we have to figure out who should receive this activity privacy = self.privacy if hasattr(self, "privacy") else "public" # is this activity owned by a user (statuses, lists, shelves), or is it # general to the instance (like books) user = self.user if hasattr(self, "user") else None user_model = apps.get_model("bookwyrm.User", require_ready=True) if not user and isinstance(self, user_model): # or maybe the thing itself is a user user = self # find anyone who's tagged in a status, for example mentions = self.recipients if hasattr(self, "recipients") else [] # we always send activities to explicitly mentioned users' inboxes recipients = [u.inbox for u in mentions or [] if not u.local] # unless it's a dm, all the followers should receive the activity if privacy != "direct": # we will send this out to a subset of all remote users queryset = ( user_model.viewer_aware_objects(user) .filter( local=False, ) .distinct() ) # filter users first by whether they're using the desired software # this lets us send book updates only to other bw servers if software: queryset = queryset.filter(bookwyrm_user=(software == "bookwyrm")) # if there's a user, we only want to send to the user's followers if user: queryset = queryset.filter(following=user) # ideally, we will send to shared inboxes for efficiency shared_inboxes = ( queryset.filter(shared_inbox__isnull=False) .values_list("shared_inbox", flat=True) .distinct() ) # but not everyone has a shared inbox inboxes = queryset.filter(shared_inbox__isnull=True).values_list( "inbox", flat=True ) recipients += list(shared_inboxes) + list(inboxes) return list(set(recipients)) def to_activity_dataclass(self): """convert from a model to an activity""" activity = generate_activity(self) return self.activity_serializer(**activity) def to_activity(self, **kwargs): # pylint: disable=unused-argument """convert from a model to a json activity""" return self.to_activity_dataclass().serialize() class ObjectMixin(ActivitypubMixin): """add this mixin for object models that are AP serializable""" def save(self, *args, created=None, software=None, **kwargs): """broadcast created/updated/deleted objects as appropriate""" broadcast = kwargs.get("broadcast", True) # this bonus kwarg would cause an error in the base save method if "broadcast" in kwargs: del kwargs["broadcast"] created = created or not bool(self.id) # first off, we want to save normally no matter what super().save(*args, **kwargs) if not broadcast or ( hasattr(self, "status_type") and self.status_type == "Announce" ): return # this will work for objects owned by a user (lists, shelves) user = self.user if hasattr(self, "user") else None if created: # broadcast Create activities for objects owned by a local user if not user or not user.local: return try: # do we have a "pure" activitypub version of this for mastodon? if not software and hasattr(self, "pure_content"): pure_activity = self.to_create_activity(user, pure=True) self.broadcast(pure_activity, user, software="other") # set bookwyrm so that that type is also sent software = "bookwyrm" if software == "bookwyrm": # sends to BW only if we just did a pure version for masto activity = self.to_create_activity(user) self.broadcast(activity, user, software=software) except AttributeError: # janky as heck, this catches the mutliple inheritence chain # for boosts and ignores this auxilliary broadcast return return # --- updating an existing object if not user: # users don't have associated users, they ARE users user_model = apps.get_model("bookwyrm.User", require_ready=True) if isinstance(self, user_model): user = self # book data tracks last editor user = user or getattr(self, "last_edited_by", None) # again, if we don't know the user or they're remote, don't bother if not user or not user.local: return # is this a deletion? if hasattr(self, "deleted") and self.deleted: activity = self.to_delete_activity(user) else: activity = self.to_update_activity(user) self.broadcast(activity, user) def to_create_activity(self, user, **kwargs): """returns the object wrapped in a Create activity""" activity_object = self.to_activity_dataclass(**kwargs) signature = None create_id = self.remote_id + "/activity" if hasattr(activity_object, "content") and activity_object.content: signer = pkcs1_15.new(RSA.import_key(user.key_pair.private_key)) content = activity_object.content signed_message = signer.sign(SHA256.new(content.encode("utf8"))) signature = activitypub.Signature( creator=f"{user.remote_id}#main-key", created=activity_object.published, signatureValue=b64encode(signed_message).decode("utf8"), ) return activitypub.Create( id=create_id, actor=user.remote_id, to=activity_object.to, cc=activity_object.cc, object=activity_object, signature=signature, ).serialize() def to_delete_activity(self, user): """notice of deletion""" return activitypub.Delete( id=self.remote_id + "/activity", actor=user.remote_id, to=[f"{user.remote_id}/followers"], cc=["https://www.w3.org/ns/activitystreams#Public"], object=self, ).serialize() def to_update_activity(self, user): """wrapper for Updates to an activity""" uuid = uuid4() return activitypub.Update( id=f"{self.remote_id}#update/{uuid}", actor=user.remote_id, to=["https://www.w3.org/ns/activitystreams#Public"], object=self, ).serialize() class OrderedCollectionPageMixin(ObjectMixin): """just the paginator utilities, so you don't HAVE to override ActivitypubMixin's to_activity (ie, for outbox)""" @property def collection_remote_id(self): """this can be overriden if there's a special remote id, ie outbox""" return self.remote_id def to_ordered_collection( self, queryset, remote_id=None, page=False, collection_only=False, **kwargs ): """an ordered collection of whatevers""" if not queryset.ordered: raise RuntimeError("queryset must be ordered") remote_id = remote_id or self.remote_id if page: if isinstance(page, list) and len(page) > 0: page = page[0] return to_ordered_collection_page(queryset, remote_id, page=page, **kwargs) if collection_only or not hasattr(self, "activity_serializer"): serializer = activitypub.OrderedCollection activity = {} else: serializer = self.activity_serializer # a dict from the model fields activity = generate_activity(self) if remote_id: activity["id"] = remote_id paginated = Paginator(queryset, PAGE_LENGTH) # add computed fields specific to orderd collections activity["totalItems"] = paginated.count activity["first"] = f"{remote_id}?page=1" activity["last"] = f"{remote_id}?page={paginated.num_pages}" return serializer(**activity) class OrderedCollectionMixin(OrderedCollectionPageMixin): """extends activitypub models to work as ordered collections""" @property def collection_queryset(self): """usually an ordered collection model aggregates a different model""" raise NotImplementedError("Model must define collection_queryset") activity_serializer = activitypub.OrderedCollection def to_activity_dataclass(self, **kwargs): return self.to_ordered_collection(self.collection_queryset, **kwargs) def to_activity(self, **kwargs): """an ordered collection of the specified model queryset""" return self.to_ordered_collection( self.collection_queryset, **kwargs ).serialize() def delete(self, *args, broadcast=True, **kwargs): """Delete the object""" activity = self.to_delete_activity(self.user) super().delete(*args, **kwargs) if self.user.local and broadcast: self.broadcast(activity, self.user) class CollectionItemMixin(ActivitypubMixin): """for items that are part of an (Ordered)Collection""" activity_serializer = activitypub.CollectionItem def broadcast(self, activity, sender, software="bookwyrm"): """only send book collection updates to other bookwyrm instances""" super().broadcast(activity, sender, software=software) @property def privacy(self): """inherit the privacy of the list, or direct if pending""" collection_field = getattr(self, self.collection_field) if self.approved: return collection_field.privacy return "direct" @property def recipients(self): """the owner of the list is a direct recipient""" collection_field = getattr(self, self.collection_field) if collection_field.user.local: # don't broadcast to yourself return [] return [collection_field.user] def save(self, *args, broadcast=True, **kwargs): """broadcast updated""" # first off, we want to save normally no matter what super().save(*args, **kwargs) # list items can be updateda, normally you would only broadcast on created if not broadcast or not self.user.local: return # adding an obj to the collection activity = self.to_add_activity(self.user) self.broadcast(activity, self.user) def delete(self, *args, broadcast=True, **kwargs): """broadcast a remove activity""" activity = self.to_remove_activity(self.user) super().delete(*args, **kwargs) if self.user.local and broadcast: self.broadcast(activity, self.user) def to_add_activity(self, user): """AP for shelving a book""" collection_field = getattr(self, self.collection_field) return activitypub.Add( id=f"{collection_field.remote_id}#add", actor=user.remote_id, object=self.to_activity_dataclass(), target=collection_field.remote_id, ).serialize() def to_remove_activity(self, user): """AP for un-shelving a book""" collection_field = getattr(self, self.collection_field) return activitypub.Remove( id=f"{collection_field.remote_id}#remove", actor=user.remote_id, object=self.to_activity_dataclass(), target=collection_field.remote_id, ).serialize() class ActivityMixin(ActivitypubMixin): """add this mixin for models that are AP serializable""" def save(self, *args, broadcast=True, **kwargs): """broadcast activity""" super().save(*args, **kwargs) user = self.user if hasattr(self, "user") else self.user_subject if broadcast and user.local: self.broadcast(self.to_activity(), user) def delete(self, *args, broadcast=True, **kwargs): """nevermind, undo that activity""" user = self.user if hasattr(self, "user") else self.user_subject if broadcast and user.local: self.broadcast(self.to_undo_activity(), user) super().delete(*args, **kwargs) def to_undo_activity(self): """undo an action""" user = self.user if hasattr(self, "user") else self.user_subject return activitypub.Undo( id=f"{self.remote_id}#undo", actor=user.remote_id, object=self, ).serialize() def generate_activity(obj): """go through the fields on an object""" activity = {} for field in obj.activity_fields: field.set_activity_from_field(activity, obj) if hasattr(obj, "serialize_reverse_fields"): # for example, editions of a work for ( model_field_name, activity_field_name, sort_field, ) in obj.serialize_reverse_fields: related_field = getattr(obj, model_field_name) activity[activity_field_name] = unfurl_related_field( related_field, sort_field=sort_field ) if not activity.get("id"): activity["id"] = obj.get_remote_id() return activity def unfurl_related_field(related_field, sort_field=None): """load reverse lookups (like public key owner or Status attachment""" if sort_field and hasattr(related_field, "all"): return [ unfurl_related_field(i) for i in related_field.order_by(sort_field).all() ] if related_field.reverse_unfurl: # if it's a one-to-one (key pair) if hasattr(related_field, "field_to_activity"): return related_field.field_to_activity() # if it's one-to-many (attachments) return related_field.to_activity() return related_field.remote_id @app.task(queue="medium_priority") def broadcast_task(sender_id, activity, recipients): """the celery task for broadcast""" user_model = apps.get_model("bookwyrm.User", require_ready=True) sender = user_model.objects.get(id=sender_id) for recipient in recipients: try: sign_and_send(sender, activity, recipient) except RequestException: pass def sign_and_send(sender, data, destination): """crpyto whatever and http junk""" now = http_date() if not sender.key_pair.private_key: # this shouldn't happen. it would be bad if it happened. raise ValueError("No private key found for sender") digest = make_digest(data) response = requests.post( destination, data=data, headers={ "Date": now, "Digest": digest, "Signature": make_signature(sender, destination, now, digest), "Content-Type": "application/activity+json; charset=utf-8", "User-Agent": USER_AGENT, }, ) if not response.ok: response.raise_for_status() return response # pylint: disable=unused-argument def to_ordered_collection_page( queryset, remote_id, id_only=False, page=1, pure=False, **kwargs ): """serialize and pagiante a queryset""" paginated = Paginator(queryset, PAGE_LENGTH) activity_page = paginated.get_page(page) if id_only: items = [s.remote_id for s in activity_page.object_list] else: items = [s.to_activity(pure=pure) for s in activity_page.object_list] prev_page = next_page = None if activity_page.has_next(): next_page = f"{remote_id}?page={activity_page.next_page_number()}" if activity_page.has_previous(): prev_page = f"{remote_id}?page=%d{activity_page.previous_page_number()}" return activitypub.OrderedCollectionPage( id=f"{remote_id}?page={page}", partOf=remote_id, orderedItems=items, next=next_page, prev=prev_page, )