Add remaining ban time to fail2ban

lib/rule.ex

@@ -98,7 +98,7 @@ defmodule PlugAttack.Rule do
   Be careful not to use the same `key` for different rules that use the same
   storage.
 
-  Passes `{:fail2ban, key}`, as the data to `block_action` calls when an
+  Passes `{:fail2ban, key, remaining_ban}`, as the data to `block_action` calls when an
   abusive request is detected. Each misbehaving client is blocked after each
   call and tracked for `:period` time. If more than `:limit` abusive requests
   are detected within the `:period`, the client is banned for `:ban_for`.
@@ -129,15 +129,17 @@ defmodule PlugAttack.Rule do
     ban_for = Keyword.fetch!(opts, :ban_for)
     now = System.system_time(:millisecond)
 
-    if banned?(key, storage, now) do
-      {:block, {:fail2ban, :banned, key}}
-    else
-      track_fail2ban(key, storage, limit, period, ban_for, now)
+    case banned?(key, storage, now) do
+      {true, remaining_ban} -> {:block, {:fail2ban, :banned, key, remaining_ban}}
+      false -> track_fail2ban(key, storage, limit, period, ban_for, now)
     end
   end
 
   defp banned?(key, {mod, opts}, now) do
-    mod.read(opts, {:fail2ban_banned, key}, now) == {:ok, true}
+    case mod.read(opts, {:fail2ban_banned, key}, now) do
+      {:ok, true, remaining_ban} -> {true, remaining_ban}
+      _ -> false
+    end
   end
 
   defp track_fail2ban(key, {mod, opts}, limit, period, ban_for, now) do

lib/storage/ets.ex

@@ -53,7 +53,7 @@ defmodule PlugAttack.Storage.Ets do
   def read(name, key, now) do
     case :ets.lookup(name, key) do
       [{^key, value, expires_at}] when expires_at > now ->
-        {:ok, value}
+        {:ok, value, expires_at - now}
 
       _ ->
         :error

test/rules_test.exs

@@ -18,7 +18,7 @@ defmodule PlugAttack.RuleTest do
     :timer.sleep(1)
     assert {:allow, {:fail2ban, :counting, :key}} = fail2ban()
     :timer.sleep(100)
-    assert {:block, {:fail2ban, :banned, :key}} = fail2ban()
+    assert {:block, {:fail2ban, :banned, :key, 99}} = fail2ban()
     :timer.sleep(200)
     assert {:allow, {:fail2ban, :counting, :key}} = fail2ban()
   end

test/storage/ets_test.exs

@@ -26,7 +26,7 @@ defmodule PlugAttack.Storage.EtsTest do
   test "read/write" do
     assert :error = Ets.read(__MODULE__, :foo, now())
     Ets.write(__MODULE__, :foo, true, expires_in(20))
-    assert {:ok, true} == Ets.read(__MODULE__, :foo, now())
+    assert {:ok, true, 20} == Ets.read(__MODULE__, :foo, now())
     :timer.sleep(30)
     assert :error = Ets.read(__MODULE__, :foo, now())
   end