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# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.Plugs.HTTPSignaturePlug do
import Plug.Conn
import Phoenix.Controller, only: [get_format: 1, text: 2]
require Logger
def init(options) do
options
end
def call(%{assigns: %{valid_signature: true}} = conn, _opts) do
conn
end
def call(conn, _opts) do
if get_format(conn) == "activity+json" do
conn
|> maybe_assign_valid_signature()
|> maybe_require_signature()
else
conn
end
end
defp maybe_assign_valid_signature(conn) do
if has_signature_header?(conn) do
# set (request-target) header to the appropriate value
# we also replace the digest header with the one we computed
request_target = String.downcase("#{conn.method}") <> " #{conn.request_path}"
conn =
conn
|> put_req_header("(request-target)", request_target)
|> case do
%{assigns: %{digest: digest}} = conn -> put_req_header(conn, "digest", digest)
conn -> conn
end
assign(conn, :valid_signature, HTTPSignatures.validate_conn(conn))
else
Logger.debug("No signature header!")
conn
end
end
defp has_signature_header?(conn) do
conn |> get_req_header("signature") |> Enum.at(0, false)
end
defp maybe_require_signature(%{assigns: %{valid_signature: true}} = conn), do: conn
defp maybe_require_signature(conn) do
if Pleroma.Config.get([:activitypub, :authorized_fetch_mode], false) do
conn
|> put_status(:unauthorized)
|> text("Request not signed")
|> halt()
else
conn
end
end
end
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