philomena/lib/philomena_web/plugs/limit_plug.ex

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2020-07-21 16:50:33 +02:00
defmodule PhilomenaWeb.LimitPlug do
@moduledoc """
This plug automatically limits requests which are submitted faster
than should be allowed for a given client.
## Example
plug PhilomenaWeb.LimitPlug, [time: 30, error: "Too fast! Slow down."]
"""
alias Plug.Conn
alias Phoenix.Controller
@doc false
@spec init(any()) :: any()
def init(opts), do: opts
@doc false
@spec call(Conn.t(), any()) :: Conn.t()
def call(conn, opts) do
limit = Keyword.get(opts, :limit, 1)
time = Keyword.get(opts, :time, 5)
error = Keyword.get(opts, :error)
data = [
current_user_id(conn.assigns.current_user),
:inet_parse.ntoa(conn.remote_ip),
conn.private.phoenix_action,
conn.private.phoenix_controller
]
key = "rl-#{Enum.join(data, "")}"
[amt, _] =
Redix.pipeline!(:redix, [
["INCR", key],
["EXPIRE", key, time]
])
cond do
amt <= limit ->
conn
true ->
conn
|> Controller.put_flash(:error, error)
|> Controller.redirect(external: conn.assigns.referrer)
|> Conn.halt()
end
end
defp current_user_id(%{id: id}), do: id
defp current_user_id(_), do: nil
end