Add LegacyAuthenticationPlug

lib/pleroma/plugs/legacy_authentication_plug.ex

@@ -0,0 +1,31 @@
+defmodule Pleroma.Plugs.LegacyAuthenticationPlug do
+  import Plug.Conn
+  alias Pleroma.User
+
+  def init(options) do
+    options
+  end
+
+  def call(%{assigns: %{user: %User{}}} = conn, _), do: conn
+
+  def call(
+        %{
+          assigns: %{
+            auth_user: %{password_hash: "$6$" <> _ = password_hash} = auth_user,
+            auth_credentials: %{password: password}
+          }
+        } = conn,
+        _
+      ) do
+    if :crypt.crypt(password, password_hash) == password_hash do
+      conn
+      |> assign(:user, auth_user)
+    else
+      conn
+    end
+  end
+
+  def call(conn, _) do
+    conn
+  end
+end