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Local copy of Akkoma, an ActivityPub server software. Contains modifications running live on fedi.underscore.world
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akkoma/lib/pleroma/object/fetcher.ex

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# 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
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
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),
{:ok, object} <- reinject_object(object, new_data) do
{:ok, object}
else
{:local, true} -> {:ok, object}
e -> {:error, e}
end
end
# Note: will create a Create activity, which we need internally at the moment.
def fetch_object_from_id(id, options \\ []) do
with %URI{} = uri <- URI.parse(id),
# 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} <- {:containment, Containment.contain_origin(id, params)},
{_, {: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."}
{:containment, _} ->
{:error, "Object containment failed."}
{:transmogrifier, {:error, {:reject, e}}} ->
{:reject, e}
{:transmogrifier, {:reject, 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, error}} ->
{:error, error}
{:reject, reason} ->
{:reject, reason}
e ->
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
def fetch_object_from_id!(id, options \\ []) do
with {:ok, object} <- fetch_object_from_id(id, options) do
object
else
{:error, %Tesla.Mock.Error{}} ->
nil
{:error, {"Object has been deleted", _id, _code}} ->
nil
{:reject, reason} ->
Logger.debug("Rejected #{id} while fetching: #{inspect(reason)}")
nil
e ->
Logger.error("Error while fetching #{id}: #{inspect(e)}")
nil
end
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
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, body} <- get_object(id),
{:ok, data} <- safe_json_decode(body),
:ok <- Containment.contain_origin_from_id(id, data) do
unless Instances.reachable?(id) do
Instances.set_reachable(id)
end
{:ok, data}
else
{:scheme, _} ->
{:error, "Unsupported URI scheme"}
{: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 get_object(id) do
date = Pleroma.Signature.signed_date()
headers =
[{"accept", "application/activity+json"}]
|> maybe_date_fetch(date)
|> sign_fetch(id, date)
case HTTP.get(id, headers) do
{:ok, %{body: body, status: code, headers: headers}} when code in 200..299 ->
case List.keyfind(headers, "content-type", 0) do
{_, content_type} ->
case Plug.Conn.Utils.media_type(content_type) do
{:ok, "application", "activity+json", _} ->
{:ok, body}
{:ok, "application", "ld+json",
%{"profile" => "https://www.w3.org/ns/activitystreams"}} ->
{:ok, body}
_ ->
{:error, {:content_type, content_type}}
end
_ ->
{:error, {:content_type, nil}}
end
{:ok, %{status: code}} when code in [404, 410] ->
{:error, {"Object has been deleted", id, code}}
{:error, e} ->
{:error, e}
e ->
{:error, e}
end
end
defp safe_json_decode(nil), do: {:ok, nil}
defp safe_json_decode(json), do: Jason.decode(json)
end