spc-pleroma/lib/pleroma/plugs/rate_limiter.ex

88 lines
2.5 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Plugs.RateLimiter do
@moduledoc """
## Configuration
A keyword list of rate limiters where a key is a limiter name and value is the limiter configuration. The basic configuration is a tuple where:
* The first element: `scale` (Integer). The time scale in milliseconds.
* The second element: `limit` (Integer). How many requests to limit in the time scale provided.
It is also possible to have different limits for unauthenticated and authenticated users: the keyword value must be a list of two tuples where the first one is a config for unauthenticated users and the second one is for authenticated.
### Example
config :pleroma, :rate_limit,
one: {1000, 10},
two: [{10_000, 10}, {10_000, 50}]
Here we have two limiters: `one` which is not over 10req/1s and `two` which has two limits 10req/10s for unauthenticated users and 50req/10s for authenticated users.
## Usage
Inside a controller:
plug(Pleroma.Plugs.RateLimiter, :one when action == :one)
plug(Pleroma.Plugs.RateLimiter, :two when action in [:two, :three])
or inside a router pipiline:
pipeline :api do
...
plug(Pleroma.Plugs.RateLimiter, :one)
...
end
"""
import Phoenix.Controller, only: [json: 2]
import Plug.Conn
alias Pleroma.User
def init(limiter_name) do
case Pleroma.Config.get([:rate_limit, limiter_name]) do
nil -> nil
config -> {limiter_name, config}
end
end
# do not limit if there is no limiter configuration
def call(conn, nil), do: conn
def call(conn, opts) do
case check_rate(conn, opts) do
{:ok, _count} -> conn
{:error, _count} -> render_error(conn)
end
end
defp check_rate(%{assigns: %{user: %User{id: user_id}}}, {limiter_name, [_, {scale, limit}]}) do
ExRated.check_rate("#{limiter_name}:#{user_id}", scale, limit)
end
defp check_rate(conn, {limiter_name, [{scale, limit} | _]}) do
ExRated.check_rate("#{limiter_name}:#{ip(conn)}", scale, limit)
end
defp check_rate(conn, {limiter_name, {scale, limit}}) do
check_rate(conn, {limiter_name, [{scale, limit}]})
end
def ip(%{remote_ip: remote_ip}) do
remote_ip
|> Tuple.to_list()
|> Enum.join(".")
end
defp render_error(conn) do
conn
|> put_status(:too_many_requests)
|> json(%{error: "Throttled"})
|> halt()
end
end