Pleroma/lib/pleroma/plugs/rate_limiter/rate_limiter.ex
rinpatch c46d035f7b rate limiter: disable based on if remote ip was found, not on if the plug was enabled
The current rate limiter disable logic won't trigger when the remote ip
is not forwarded, only when the remoteip plug is not enabled, which is
not the case on most instances since it's enabled by default. This
changes the behavior to warn and disable  when the remote ip was not forwarded,
even if the RemoteIP plug is enabled.

Also closes 
2020-03-16 00:15:21 +03:00

279 lines
7.7 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 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.Config
alias Pleroma.Plugs.RateLimiter.LimiterSupervisor
alias Pleroma.User
require Logger
@doc false
def init(plug_opts) do
plug_opts
end
def call(conn, plug_opts) do
if disabled?(conn) do
handle_disabled(conn)
else
action_settings = action_settings(plug_opts)
handle(conn, action_settings)
end
end
defp handle_disabled(conn) do
Logger.warn(
"Rate limiter disabled due to forwarded IP not being found. Please ensure your reverse proxy is providing the X-Forwarded-For header or disable the RemoteIP plug/rate limiter."
)
conn
end
defp handle(conn, nil), do: conn
defp handle(conn, action_settings) do
action_settings
|> incorporate_conn_info(conn)
|> check_rate()
|> case do
{:ok, _count} ->
conn
{:error, _count} ->
render_throttled_error(conn)
end
end
def disabled?(conn) do
localhost_or_socket =
case Config.get([Pleroma.Web.Endpoint, :http, :ip]) do
{127, 0, 0, 1} -> true
{0, 0, 0, 0, 0, 0, 0, 1} -> true
{:local, _} -> true
_ -> false
end
remote_ip_not_found =
if Map.has_key?(conn.assigns, :remote_ip_found),
do: !conn.assigns.remote_ip_found,
else: false
localhost_or_socket and remote_ip_not_found
end
@inspect_bucket_not_found {:error, :not_found}
def inspect_bucket(conn, bucket_name_root, plug_opts) do
with %{name: _} = action_settings <- action_settings(plug_opts) do
action_settings = incorporate_conn_info(action_settings, conn)
bucket_name = make_bucket_name(%{action_settings | name: bucket_name_root})
key_name = make_key_name(action_settings)
limit = get_limits(action_settings)
case Cachex.get(bucket_name, key_name) do
{:error, :no_cache} ->
@inspect_bucket_not_found
{:ok, nil} ->
{0, limit}
{:ok, value} ->
{value, limit - value}
end
else
_ -> @inspect_bucket_not_found
end
end
def action_settings(plug_opts) do
with limiter_name when is_atom(limiter_name) <- plug_opts[:name],
limits when not is_nil(limits) <- Config.get([:rate_limit, limiter_name]) do
bucket_name_root = Keyword.get(plug_opts, :bucket_name, limiter_name)
%{
name: bucket_name_root,
limits: limits,
opts: plug_opts
}
end
end
defp check_rate(action_settings) do
bucket_name = make_bucket_name(action_settings)
key_name = make_key_name(action_settings)
limit = get_limits(action_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!(action_settings)
check_rate(action_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(action_settings, %{
assigns: %{user: %User{id: user_id}},
params: params
}) do
Map.merge(action_settings, %{
mode: :user,
conn_params: params,
conn_info: "#{user_id}"
})
end
defp incorporate_conn_info(action_settings, %{params: params} = conn) do
Map.merge(action_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(action_settings) do
""
|> attach_selected_params(action_settings)
|> attach_identity(action_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: bucket_name_root}),
do: user_bucket_name(bucket_name_root)
defp make_bucket_name(%{mode: :anon, name: bucket_name_root}),
do: anon_bucket_name(bucket_name_root)
defp attach_selected_params(input, %{conn_params: conn_params, opts: plug_opts}) do
params_string =
plug_opts
|> Keyword.get(:params, [])
|> Enum.sort()
|> Enum.map(&Map.get(conn_params, &1, ""))
|> Enum.join(":")
[input, params_string]
|> Enum.join(":")
|> String.replace_leading(":", "")
end
defp initialize_buckets!(%{name: _name, limits: nil}), do: :ok
defp initialize_buckets!(%{name: name, limits: limits}) do
{:ok, _pid} =
LimiterSupervisor.add_or_return_limiter(anon_bucket_name(name), get_scale(:anon, limits))
{:ok, _pid} =
LimiterSupervisor.add_or_return_limiter(user_bucket_name(name), get_scale(:user, limits))
:ok
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(bucket_name_root), do: "user:#{bucket_name_root}" |> String.to_atom()
defp anon_bucket_name(bucket_name_root), do: "anon:#{bucket_name_root}" |> String.to_atom()
end