# Pleroma: A lightweight social networking server # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/> # SPDX-License-Identifier: AGPL-3.0-only defmodule Pleroma.Plugs.IdempotencyPlug do import Phoenix.Controller, only: [json: 2] import Plug.Conn @behaviour Plug @impl true def init(opts), do: opts # Sending idempotency keys in `GET` and `DELETE` requests has no effect # and should be avoided, as these requests are idempotent by definition. @impl true def call(%{method: method} = conn, _) when method in ["POST", "PUT", "PATCH"] do case get_req_header(conn, "idempotency-key") do [key] -> process_request(conn, key) _ -> conn end end def call(conn, _), do: conn def process_request(conn, key) do case Cachex.get(:idempotency_cache, key) do {:ok, nil} -> cache_resposnse(conn, key) {:ok, record} -> send_cached(conn, key, record) {atom, message} when atom in [:ignore, :error] -> render_error(conn, message) end end defp cache_resposnse(conn, key) do register_before_send(conn, fn conn -> [request_id] = get_resp_header(conn, "x-request-id") content_type = get_content_type(conn) record = {request_id, content_type, conn.status, conn.resp_body} {:ok, _} = Cachex.put(:idempotency_cache, key, record) conn |> put_resp_header("idempotency-key", key) |> put_resp_header("x-original-request-id", request_id) end) end defp send_cached(conn, key, record) do {request_id, content_type, status, body} = record conn |> put_resp_header("idempotency-key", key) |> put_resp_header("idempotent-replayed", "true") |> put_resp_header("x-original-request-id", request_id) |> put_resp_content_type(content_type) |> send_resp(status, body) |> halt() end defp render_error(conn, message) do conn |> put_status(:unprocessable_entity) |> json(%{error: message}) |> halt() end defp get_content_type(conn) do [content_type] = get_resp_header(conn, "content-type") if String.contains?(content_type, ";") do content_type |> String.split(";") |> hd() else content_type end end end