moviewyrm/bookwyrm/views/inbox.py
2021-09-07 16:33:43 -07:00

132 lines
4.4 KiB
Python

""" incoming activities """
import json
import re
from urllib.parse import urldefrag
from django.http import HttpResponse, HttpResponseNotFound
from django.http import HttpResponseBadRequest, HttpResponseForbidden
from django.utils.decorators import method_decorator
from django.views import View
from django.views.decorators.csrf import csrf_exempt
import requests
from bookwyrm import activitypub, models
from bookwyrm.tasks import app
from bookwyrm.signatures import Signature
from bookwyrm.utils import regex
@method_decorator(csrf_exempt, name="dispatch")
# pylint: disable=no-self-use
class Inbox(View):
"""requests sent by outside servers"""
# pylint: disable=too-many-return-statements
def post(self, request, username=None):
"""only works as POST request"""
# first check if this server is on our shitlist
if is_blocked_user_agent(request):
return HttpResponseForbidden()
# make sure the user's inbox even exists
if username:
try:
models.User.objects.get(localname=username)
except models.User.DoesNotExist:
return HttpResponseNotFound()
# is it valid json? does it at least vaguely resemble an activity?
try:
activity_json = json.loads(request.body)
except json.decoder.JSONDecodeError:
return HttpResponseBadRequest()
# let's be extra sure we didn't block this domain
if is_blocked_activity(activity_json):
return HttpResponseForbidden()
if (
not "object" in activity_json
or not "type" in activity_json
or not activity_json["type"] in activitypub.activity_objects
):
return HttpResponseNotFound()
# verify the signature
if not has_valid_signature(request, activity_json):
if activity_json["type"] == "Delete":
# Pretend that unauth'd deletes succeed. Auth may be failing
# because the resource or owner of the resource might have
# been deleted.
return HttpResponse()
return HttpResponse(status=401)
activity_task.delay(activity_json)
return HttpResponse()
def is_blocked_user_agent(request):
"""check if a request is from a blocked server based on user agent"""
# check user agent
user_agent = request.headers.get("User-Agent")
if not user_agent:
return False
url = re.search(r"https?://{:s}/?".format(regex.DOMAIN), user_agent)
if not url:
return False
url = url.group()
return models.FederatedServer.is_blocked(url)
def is_blocked_activity(activity_json):
"""get the sender out of activity json and check if it's blocked"""
actor = activity_json.get("actor")
# check if the user is banned/deleted
existing = models.User.find_existing_by_remote_id(actor)
if existing and existing.deleted:
return True
if not actor:
# well I guess it's not even a valid activity so who knows
return False
return models.FederatedServer.is_blocked(actor)
@app.task(queue="medium_priority")
def activity_task(activity_json):
"""do something with this json we think is legit"""
# lets see if the activitypub module can make sense of this json
activity = activitypub.parse(activity_json)
# cool that worked, now we should do the action described by the type
# (create, update, delete, etc)
activity.action()
def has_valid_signature(request, activity):
"""verify incoming signature"""
try:
signature = Signature.parse(request)
key_actor = urldefrag(signature.key_id).url
if key_actor != activity.get("actor"):
raise ValueError("Wrong actor created signature.")
remote_user = activitypub.resolve_remote_id(key_actor, model=models.User)
if not remote_user:
return False
try:
signature.verify(remote_user.key_pair.public_key, request)
except ValueError:
old_key = remote_user.key_pair.public_key
remote_user = activitypub.resolve_remote_id(
remote_user.remote_id, model=models.User, refresh=True
)
if remote_user.key_pair.public_key == old_key:
raise # Key unchanged.
signature.verify(remote_user.key_pair.public_key, request)
except (ValueError, requests.exceptions.HTTPError):
return False
return True