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diff --git a/lib/pleroma/object/fetcher.ex b/lib/pleroma/object/fetcher.ex
index dc13810c8..431ad4845 100644
--- a/lib/pleroma/object/fetcher.ex
+++ b/lib/pleroma/object/fetcher.ex
@@ -1,374 +1,369 @@
# Pleroma: A lightweight social networking server
# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Object.Fetcher do
alias Pleroma.HTTP
alias Pleroma.Instances
alias Pleroma.Maps
alias Pleroma.Object
alias Pleroma.Object.Containment
alias Pleroma.Repo
alias Pleroma.Signature
alias Pleroma.Web.ActivityPub.InternalFetchActor
alias Pleroma.Web.ActivityPub.ObjectValidator
alias Pleroma.Web.ActivityPub.Transmogrifier
alias Pleroma.Web.Federator
require Logger
require Pleroma.Constants
@moduledoc """
This module deals with correctly fetching Acitivity Pub objects in a safe way.
The core function is `fetch_and_contain_remote_object_from_id/1` which performs
the actual fetch and common safety and authenticity checks. Other `fetch_*`
function use the former and perform some additional tasks
"""
@mix_env Mix.env()
defp touch_changeset(changeset) do
updated_at =
NaiveDateTime.utc_now()
|> NaiveDateTime.truncate(:second)
Ecto.Changeset.put_change(changeset, :updated_at, updated_at)
end
defp maybe_reinject_internal_fields(%{data: %{} = old_data}, new_data) do
has_history? = fn
%{"formerRepresentations" => %{"orderedItems" => list}} when is_list(list) -> true
_ -> false
end
internal_fields = Map.take(old_data, Pleroma.Constants.object_internal_fields())
remote_history_exists? = has_history?.(new_data)
# If the remote history exists, we treat that as the only source of truth.
new_data =
if has_history?.(old_data) and not remote_history_exists? do
Map.put(new_data, "formerRepresentations", old_data["formerRepresentations"])
else
new_data
end
# If the remote does not have history information, we need to manage it ourselves
new_data =
if not remote_history_exists? do
changed? =
Pleroma.Constants.status_updatable_fields()
|> Enum.any?(fn field -> Map.get(old_data, field) != Map.get(new_data, field) end)
%{updated_object: updated_object} =
new_data
|> Object.Updater.maybe_update_history(old_data,
updated: changed?,
use_history_in_new_object?: false
)
updated_object
else
new_data
end
Map.merge(new_data, internal_fields)
end
defp maybe_reinject_internal_fields(_, new_data), do: new_data
@spec reinject_object(struct(), map()) :: {:ok, Object.t()} | {:error, any()}
defp reinject_object(%Object{data: %{"type" => "Question"}} = object, new_data) do
Logger.debug("Reinjecting object #{new_data["id"]}")
with data <- maybe_reinject_internal_fields(object, new_data),
{:ok, data, _} <- ObjectValidator.validate(data, %{}),
changeset <- Object.change(object, %{data: data}),
changeset <- touch_changeset(changeset),
{:ok, object} <- Repo.insert_or_update(changeset),
{:ok, object} <- Object.set_cache(object) do
{:ok, object}
else
e ->
Logger.error("Error while processing object: #{inspect(e)}")
{:error, e}
end
end
defp reinject_object(%Object{} = object, new_data) do
Logger.debug("Reinjecting object #{new_data["id"]}")
with new_data <- Transmogrifier.fix_object(new_data),
data <- maybe_reinject_internal_fields(object, new_data),
changeset <- Object.change(object, %{data: data}),
changeset <- touch_changeset(changeset),
{:ok, object} <- Repo.insert_or_update(changeset),
{:ok, object} <- Object.set_cache(object) do
{:ok, object}
else
e ->
Logger.error("Error while processing object: #{inspect(e)}")
{:error, e}
end
end
@doc "Assumes object already is in our database and refetches from remote to update (e.g. for polls)"
def refetch_object(%Object{data: %{"id" => id}} = object) do
with {:local, false} <- {:local, Object.local?(object)},
{:ok, new_data} <- fetch_and_contain_remote_object_from_id(id),
{:id, true} <- {:id, new_data["id"] == id},
{:ok, object} <- reinject_object(object, new_data) do
{:ok, object}
else
{:local, true} -> {:ok, object}
{:id, false} -> {:error, "Object id changed on refetch"}
e -> {:error, e}
end
end
@doc """
Fetches a new object and puts it through the processing pipeline for inbound objects
Note: will also insert a fake Create activity, since atm we internally
need everything to be traced back to a Create activity.
"""
def fetch_object_from_id(id, options \\ []) do
with %URI{} = uri <- URI.parse(id),
# let's check the URI is even vaguely valid first
{:scheme, true} <- {:scheme, uri.scheme == "http" or uri.scheme == "https"},
# If we have instance restrictions, apply them here to prevent fetching from unwanted instances
{:ok, nil} <- Pleroma.Web.ActivityPub.MRF.SimplePolicy.check_reject(uri),
{:ok, _} <- Pleroma.Web.ActivityPub.MRF.SimplePolicy.check_accept(uri),
{_, nil} <- {:fetch_object, Object.get_cached_by_ap_id(id)},
{_, true} <- {:allowed_depth, Federator.allowed_thread_distance?(options[:depth])},
{_, {:ok, data}} <- {:fetch, fetch_and_contain_remote_object_from_id(id)},
{_, nil} <- {:normalize, Object.normalize(data, fetch: false)},
params <- prepare_activity_params(data),
{_, {:ok, activity}} <-
{:transmogrifier, Transmogrifier.handle_incoming(params, options)},
{_, _data, %Object{} = object} <-
{:object, data, Object.normalize(activity, fetch: false)} do
{:ok, object}
else
{:allowed_depth, false} ->
{:error, "Max thread distance exceeded."}
{:scheme, false} ->
{:error, "URI Scheme Invalid"}
{:containment, e} ->
Logger.info("Error while fetching #{id}: Object containment failed. #{inspect(e)}")
{:error, e}
{:transmogrifier, {:error, {:reject, e}}} ->
Logger.info("Rejected #{id} while fetching: #{inspect(e)}")
{:reject, e}
{:transmogrifier, {:reject, e}} ->
Logger.info("Rejected #{id} while fetching: #{inspect(e)}")
{:reject, e}
{:transmogrifier, _} = e ->
{:error, e}
{:object, data, nil} ->
reinject_object(%Object{}, data)
{:normalize, object = %Object{}} ->
{:ok, object}
{:fetch_object, %Object{} = object} ->
{:ok, object}
- {:fetch, {:error, {:ok, %Tesla.Env{status: 403}}}} ->
- Instances.set_consistently_unreachable(id)
-
- Logger.error(
- "Error while fetching #{id}: HTTP 403 likely due to instance block rejecting the signed fetch."
- )
-
- {:error, "Object fetch has been denied"}
-
{:fetch, {:error, error}} ->
Logger.error("Error while fetching #{id}: #{inspect(error)}")
{:error, error}
{:reject, reason} ->
{:reject, reason}
e ->
Logger.error("Error while fetching #{id}: #{inspect(e)}")
{:error, e}
end
end
defp prepare_activity_params(data) do
%{
"type" => "Create",
# Should we seriously keep this attributedTo thing?
"actor" => data["actor"] || data["attributedTo"],
"object" => data
}
|> Maps.put_if_present("to", data["to"])
|> Maps.put_if_present("cc", data["cc"])
|> Maps.put_if_present("bto", data["bto"])
|> Maps.put_if_present("bcc", data["bcc"])
end
defp make_signature(id, date) do
uri = URI.parse(id)
signature =
InternalFetchActor.get_actor()
|> Signature.sign(%{
"(request-target)": "get #{uri.path}",
host: uri.host,
date: date
})
{"signature", signature}
end
defp sign_fetch(headers, id, date) do
if Pleroma.Config.get([:activitypub, :sign_object_fetches]) do
[make_signature(id, date) | headers]
else
headers
end
end
defp maybe_date_fetch(headers, date) do
if Pleroma.Config.get([:activitypub, :sign_object_fetches]) do
[{"date", date} | headers]
else
headers
end
end
@doc "Fetches arbitrary remote object and performs basic safety and authenticity checks"
def fetch_and_contain_remote_object_from_id(id)
def fetch_and_contain_remote_object_from_id(%{"id" => id}),
do: fetch_and_contain_remote_object_from_id(id)
def fetch_and_contain_remote_object_from_id(id) when is_binary(id) do
Logger.debug("Fetching object #{id} via AP")
with {:scheme, true} <- {:scheme, String.starts_with?(id, "http")},
{_, :ok} <- {:local_fetch, Containment.contain_local_fetch(id)},
{:ok, final_id, body} <- get_object(id),
{:ok, data} <- safe_json_decode(body),
{_, :ok} <- {:strict_id, Containment.contain_id_to_fetch(final_id, data)},
{_, :ok} <- {:containment, Containment.contain_origin(final_id, data)} do
unless Instances.reachable?(final_id) do
Instances.set_reachable(final_id)
end
{:ok, data}
else
{:strict_id, _} ->
{:error, "Object's ActivityPub id/url does not match final fetch URL"}
{:scheme, _} ->
{:error, "Unsupported URI scheme"}
{:local_fetch, _} ->
{:error, "Trying to fetch local resource"}
{:containment, _} ->
{:error, "Object containment failed."}
{:error, e} ->
{:error, e}
e ->
{:error, e}
end
end
def fetch_and_contain_remote_object_from_id(_id),
do: {:error, "id must be a string"}
defp check_crossdomain_redirect(final_host, original_url)
# HOPEFULLY TEMPORARY
# Basically none of our Tesla mocks in tests set the (supposed to
# exist for Tesla proper) url parameter for their responses
# causing almost every fetch in test to fail otherwise
if @mix_env == :test do
defp check_crossdomain_redirect(nil, _) do
{:cross_domain_redirect, false}
end
end
defp check_crossdomain_redirect(final_host, original_url) do
{:cross_domain_redirect, final_host != URI.parse(original_url).host}
end
if @mix_env == :test do
defp get_final_id(nil, initial_url), do: initial_url
defp get_final_id("", initial_url), do: initial_url
end
defp get_final_id(final_url, _intial_url) do
final_url
end
@doc "Do NOT use; only public for use in tests"
def get_object(id) do
date = Pleroma.Signature.signed_date()
headers =
[
# The first is required by spec, the second provided as a fallback for buggy implementations
{"accept", "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""},
{"accept", "application/activity+json"}
]
|> maybe_date_fetch(date)
|> sign_fetch(id, date)
with {:ok, %{body: body, status: code, headers: headers, url: final_url}}
when code in 200..299 <-
HTTP.get(id, headers),
remote_host <-
URI.parse(final_url).host,
{:cross_domain_redirect, false} <-
check_crossdomain_redirect(remote_host, id),
{:has_content_type, {_, content_type}} <-
{:has_content_type, List.keyfind(headers, "content-type", 0)},
{:parse_content_type, {:ok, "application", subtype, type_params}} <-
{:parse_content_type, Plug.Conn.Utils.media_type(content_type)} do
final_id = get_final_id(final_url, id)
case {subtype, type_params} do
{"activity+json", _} ->
{:ok, final_id, body}
{"ld+json", %{"profile" => "https://www.w3.org/ns/activitystreams"}} ->
{:ok, final_id, body}
_ ->
{:error, {:content_type, content_type}}
end
else
+ {:ok, %{status: 403}} ->
+ Instances.set_consistently_unreachable(id)
+ {:error, "Object fetch has been denied"}
+
{:ok, %{status: code}} when code in [404, 410] ->
{:error, {"Object has been deleted", id, code}}
{:error, e} ->
{:error, e}
{:has_content_type, _} ->
{:error, {:content_type, nil}}
{:parse_content_type, e} ->
{:error, {:content_type, e}}
e ->
{:error, e}
end
end
defp safe_json_decode(nil), do: {:ok, nil}
defp safe_json_decode(json), do: Jason.decode(json)
end

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