qb_akkoma/lib/pleroma/plugs/rate_limiter/rate_limiter.ex
2019-11-11 12:13:06 +00:00

227 lines
6.2 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.
To disable a limiter set its value to `nil`.
### Example
config :pleroma, :rate_limit,
one: {1000, 10},
two: [{10_000, 10}, {10_000, 50}],
foobar: nil
Here we have three limiters:
* `one` which is not over 10req/1s
* `two` which has two limits: 10req/10s for unauthenticated users and 50req/10s for authenticated users
* `foobar` which is disabled
## Usage
AllowedSyntax:
plug(Pleroma.Plugs.RateLimiter, name: :limiter_name)
plug(Pleroma.Plugs.RateLimiter, options) # :name is a required option
Allowed options:
* `name` required, always used to fetch the limit values from the config
* `bucket_name` overrides name for counting purposes (e.g. to have a separate limit for a set of actions)
* `params` appends values of specified request params (e.g. ["id"]) to bucket name
Inside a controller:
plug(Pleroma.Plugs.RateLimiter, [name: :one] when action == :one)
plug(Pleroma.Plugs.RateLimiter, [name: :two] when action in [:two, :three])
plug(
Pleroma.Plugs.RateLimiter,
[name: :status_id_action, bucket_name: "status_id_action:fav_unfav", params: ["id"]]
when action in ~w(fav_status unfav_status)a
)
or inside a router pipeline:
pipeline :api do
...
plug(Pleroma.Plugs.RateLimiter, name: :one)
...
end
"""
import Pleroma.Web.TranslationHelpers
import Plug.Conn
alias Pleroma.Plugs.RateLimiter.LimiterSupervisor
alias Pleroma.User
def init(opts) do
limiter_name = Keyword.get(opts, :name)
case Pleroma.Config.get([:rate_limit, limiter_name]) do
nil ->
nil
config ->
name_root = Keyword.get(opts, :bucket_name, limiter_name)
%{
name: name_root,
limits: config,
opts: opts
}
end
end
# Do not limit if there is no limiter configuration
def call(conn, nil), do: conn
def call(conn, settings) do
settings
|> incorporate_conn_info(conn)
|> check_rate()
|> case do
{:ok, _count} ->
conn
{:error, _count} ->
render_throttled_error(conn)
end
end
def inspect_bucket(conn, name_root, settings) do
settings =
settings
|> incorporate_conn_info(conn)
bucket_name = make_bucket_name(%{settings | name: name_root})
key_name = make_key_name(settings)
limit = get_limits(settings)
case Cachex.get(bucket_name, key_name) do
{:error, :no_cache} ->
{:err, :not_found}
{:ok, nil} ->
{0, limit}
{:ok, value} ->
{value, limit - value}
end
end
defp check_rate(settings) do
bucket_name = make_bucket_name(settings)
key_name = make_key_name(settings)
limit = get_limits(settings)
case Cachex.get_and_update(bucket_name, key_name, &increment_value(&1, limit)) do
{:commit, value} ->
{:ok, value}
{:ignore, value} ->
{:error, value}
{:error, :no_cache} ->
initialize_buckets(settings)
check_rate(settings)
end
end
defp increment_value(nil, _limit), do: {:commit, 1}
defp increment_value(val, limit) when val >= limit, do: {:ignore, val}
defp increment_value(val, _limit), do: {:commit, val + 1}
defp incorporate_conn_info(settings, %{assigns: %{user: %User{id: user_id}}, params: params}) do
Map.merge(settings, %{
mode: :user,
conn_params: params,
conn_info: "#{user_id}"
})
end
defp incorporate_conn_info(settings, %{params: params} = conn) do
Map.merge(settings, %{
mode: :anon,
conn_params: params,
conn_info: "#{ip(conn)}"
})
end
defp ip(%{remote_ip: remote_ip}) do
remote_ip
|> Tuple.to_list()
|> Enum.join(".")
end
defp render_throttled_error(conn) do
conn
|> render_error(:too_many_requests, "Throttled")
|> halt()
end
defp make_key_name(settings) do
""
|> attach_params(settings)
|> attach_identity(settings)
end
defp get_scale(_, {scale, _}), do: scale
defp get_scale(:anon, [{scale, _}, {_, _}]), do: scale
defp get_scale(:user, [{_, _}, {scale, _}]), do: scale
defp get_limits(%{limits: {_scale, limit}}), do: limit
defp get_limits(%{mode: :user, limits: [_, {_, limit}]}), do: limit
defp get_limits(%{limits: [{_, limit}, _]}), do: limit
defp make_bucket_name(%{mode: :user, name: name_root}),
do: user_bucket_name(name_root)
defp make_bucket_name(%{mode: :anon, name: name_root}),
do: anon_bucket_name(name_root)
defp attach_params(input, %{conn_params: conn_params, opts: opts}) do
param_string =
opts
|> Keyword.get(:params, [])
|> Enum.sort()
|> Enum.map(&Map.get(conn_params, &1, ""))
|> Enum.join(":")
"#{input}#{param_string}"
end
defp initialize_buckets(%{name: _name, limits: nil}), do: :ok
defp initialize_buckets(%{name: name, limits: limits}) do
LimiterSupervisor.add_limiter(anon_bucket_name(name), get_scale(:anon, limits))
LimiterSupervisor.add_limiter(user_bucket_name(name), get_scale(:user, limits))
end
defp attach_identity(base, %{mode: :user, conn_info: conn_info}),
do: "user:#{base}:#{conn_info}"
defp attach_identity(base, %{mode: :anon, conn_info: conn_info}),
do: "ip:#{base}:#{conn_info}"
defp user_bucket_name(name_root), do: "user:#{name_root}" |> String.to_atom()
defp anon_bucket_name(name_root), do: "anon:#{name_root}" |> String.to_atom()
end