moviewyrm/bookwyrm/models/activitypub_mixin.py
2021-02-09 17:26:27 -08:00

497 lines
18 KiB
Python

''' activitypub model functionality '''
from base64 import b64encode
from functools import reduce
import json
import operator
import logging
from uuid import uuid4
import requests
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!
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 '''
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
# 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 []]
# 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.objects.filter(
local=False,
)
# 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 recipients
def to_activity(self):
''' convert from a model to an activity '''
activity = generate_activity(self)
return self.activity_serializer(**activity).serialize()
class ObjectMixin(ActivitypubMixin):
''' add this mixin for object models that are AP serializable '''
def save(self, *args, created=None, **kwargs):
''' broadcast created/updated/deleted objects as appropriate '''
broadcast = kwargs.get('broadcast', True)
# this bonus kwarg woul 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:
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:
software = None
# do we have a "pure" activitypub version of this for mastodon?
if hasattr(self, 'pure_content'):
pure_activity = self.to_create_activity(user, pure=True)
self.broadcast(pure_activity, user, software='other')
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 KeyError:
# 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
elif hasattr(self, 'last_edited_by'):
user = self.last_edited_by
# 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(**kwargs)
signature = None
create_id = self.remote_id + '/activity'
if 'content' in activity_object 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='%s#main-key' % user.remote_id,
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=['%s/followers' % user.remote_id],
cc=['https://www.w3.org/ns/activitystreams#Public'],
object=self.to_activity(),
).serialize()
def to_update_activity(self, user):
''' wrapper for Updates to an activity '''
activity_id = '%s#update/%s' % (self.remote_id, uuid4())
return activitypub.Update(
id=activity_id,
actor=user.remote_id,
to=['https://www.w3.org/ns/activitystreams#Public'],
object=self.to_activity()
).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:
return to_ordered_collection_page(
queryset, remote_id, **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'] = '%s?page=1' % remote_id
activity['last'] = '%s?page=%d' % (remote_id, paginated.num_pages)
return serializer(**activity).serialize()
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(self, **kwargs):
''' an ordered collection of the specified model queryset '''
return self.to_ordered_collection(self.collection_queryset, **kwargs)
class CollectionItemMixin(ActivitypubMixin):
''' for items that are part of an (Ordered)Collection '''
activity_serializer = activitypub.Add
object_field = collection_field = None
def save(self, *args, broadcast=True, **kwargs):
''' broadcast updated '''
created = not bool(self.id)
# first off, we want to save normally no matter what
super().save(*args, **kwargs)
# these shouldn't be edited, only created and deleted
if not broadcast or not created or not self.user.local:
return
# adding an obj to the collection
activity = self.to_add_activity()
self.broadcast(activity, self.user)
def delete(self, *args, **kwargs):
''' broadcast a remove activity '''
activity = self.to_remove_activity()
super().delete(*args, **kwargs)
self.broadcast(activity, self.user)
def to_add_activity(self):
''' AP for shelving a book'''
object_field = getattr(self, self.object_field)
collection_field = getattr(self, self.collection_field)
return activitypub.Add(
id='%s#add' % self.remote_id,
actor=self.user.remote_id,
object=object_field.to_activity(),
target=collection_field.remote_id
).serialize()
def to_remove_activity(self):
''' AP for un-shelving a book'''
object_field = getattr(self, self.object_field)
collection_field = getattr(self, self.collection_field)
return activitypub.Remove(
id='%s#remove' % self.remote_id,
actor=self.user.remote_id,
object=object_field.to_activity(),
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='%s#undo' % self.remote_id,
actor=user.remote_id,
object=self.to_activity()
).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)
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 hasattr(related_field, 'all'):
return [unfurl_related_field(i) for i in related_field.order_by(
sort_field).all()]
if related_field.reverse_unfurl:
return related_field.field_to_activity()
return related_field.remote_id
@app.task
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 requests.exceptions.HTTPError as e:
logger.exception(e)
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, **kwargs):
''' serialize and pagiante a queryset '''
paginated = Paginator(queryset, PAGE_LENGTH)
activity_page = paginated.page(page)
if id_only:
items = [s.remote_id for s in activity_page.object_list]
else:
items = [s.to_activity() for s in activity_page.object_list]
prev_page = next_page = None
if activity_page.has_next():
next_page = '%s?page=%d' % (remote_id, activity_page.next_page_number())
if activity_page.has_previous():
prev_page = '%s?page=%d' % \
(remote_id, activity_page.previous_page_number())
return activitypub.OrderedCollectionPage(
id='%s?page=%s' % (remote_id, page),
partOf=remote_id,
orderedItems=items,
next=next_page,
prev=prev_page
).serialize()