From fc226f6c6823dee62db0ffa79084b243657a1450 Mon Sep 17 00:00:00 2001
From: Chocobozzz <me@florianbigard.com>
Date: Fri, 7 Dec 2018 10:47:31 +0100
Subject: [PATCH] Add digest, date and request-target in HTTP signature

---
 lib/service/activity_pub/activity_pub.ex      | 23 +++++++++++++++----
 .../http_signatures/http_signatures.ex        | 18 +++++++++++++++
 mix.exs                                       |  2 +-
 .../service/activitypub/activitypub_test.exs  | 18 +++++++++++++++
 4 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/lib/service/activity_pub/activity_pub.ex b/lib/service/activity_pub/activity_pub.ex
index 7c07452d8..ee44e1d43 100644
--- a/lib/service/activity_pub/activity_pub.ex
+++ b/lib/service/activity_pub/activity_pub.ex
@@ -15,6 +15,7 @@ defmodule Mobilizon.Service.ActivityPub do
   alias Mobilizon.Actors.Actor
 
   alias Mobilizon.Service.Federator
+  alias Mobilizon.Service.HTTPSignatures
 
   require Logger
   import Mobilizon.Service.ActivityPub.Utils
@@ -277,23 +278,35 @@ defmodule Mobilizon.Service.ActivityPub do
 
   def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
     Logger.info("Federating #{id} to #{inbox}")
-    host = URI.parse(inbox).host
+    {host, path} = URI.parse(inbox)
+
+    digest = HTTPSignatures.build_digest(json)
+    date = HTTPSignatures.generate_date_header()
+    request_target = HTTPSignatures.generate_request_target("POST", path)
 
     signature =
-      Mobilizon.Service.HTTPSignatures.sign(actor, %{
+      HTTPSignatures.sign(actor, %{
         host: host,
-        "content-length": byte_size(json)
+        "content-length": byte_size(json),
+        "(request-target)": request_target,
+        digest: digest,
+        date: date
       })
 
     HTTPoison.post(
       inbox,
       json,
-      [{"Content-Type", "application/activity+json"}, {"signature", signature}],
+      [
+        {"Content-Type", "application/activity+json"},
+        {"signature", signature},
+        {"digest", digest},
+        {"date", date}
+      ],
       hackney: [pool: :default]
     )
   end
 
-  # Fetching a remote actor's informations through it's AP ID 
+  # Fetching a remote actor's informations through it's AP ID
   @spec fetch_and_prepare_actor_from_url(String.t()) :: {:ok, struct()} | {:error, atom()} | any()
   defp fetch_and_prepare_actor_from_url(url) do
     Logger.debug("Fetching and preparing actor from url")
diff --git a/lib/service/http_signatures/http_signatures.ex b/lib/service/http_signatures/http_signatures.ex
index ef4aae7cf..9c1a320fc 100644
--- a/lib/service/http_signatures/http_signatures.ex
+++ b/lib/service/http_signatures/http_signatures.ex
@@ -94,6 +94,24 @@ defmodule Mobilizon.Service.HTTPSignatures do
       err ->
         Logger.error("Unable to sign headers")
         Logger.error(inspect(err))
+        nil
     end
   end
+
+  def generate_date_header(date \\ Timex.now("GMT")) do
+    with {:ok, date} <- Timex.format(date, "%a, %d %b %Y %H:%M:%S %Z", :strftime) do
+      date
+    else
+      {:error, err} ->
+        Logger.error("Unable to generate date header")
+        Logger.error(inspect(err))
+        nil
+    end
+  end
+
+  def generate_request_target(method, path), do: "#{method} #{path}"
+
+  def build_digest(body) do
+    "SHA-256=" <> (:crypto.hash(:sha256, body) |> Base.encode64())
+  end
 end
diff --git a/mix.exs b/mix.exs
index 8725cf8d8..30476dbb7 100644
--- a/mix.exs
+++ b/mix.exs
@@ -35,7 +35,7 @@ defmodule Mobilizon.Mixfile do
   def application do
     [
       mod: {Mobilizon.Application, []},
-      extra_applications: [:logger, :runtime_tools, :guardian, :bamboo, :geolix]
+      extra_applications: [:logger, :runtime_tools, :guardian, :bamboo, :geolix, :crypto]
     ]
   end
 
diff --git a/test/mobilizon/service/activitypub/activitypub_test.exs b/test/mobilizon/service/activitypub/activitypub_test.exs
index 714bed538..d9c004102 100644
--- a/test/mobilizon/service/activitypub/activitypub_test.exs
+++ b/test/mobilizon/service/activitypub/activitypub_test.exs
@@ -6,6 +6,7 @@ defmodule Mobilizon.Service.Activitypub.ActivitypubTest do
   alias Mobilizon.Events
   alias Mobilizon.Actors.Actor
   alias Mobilizon.Actors
+  alias Mobilizon.Service.HTTPSignatures
   alias Mobilizon.Service.ActivityPub
   use ExVCR.Mock, adapter: ExVCR.Adapter.Hackney
 
@@ -13,6 +14,23 @@ defmodule Mobilizon.Service.Activitypub.ActivitypubTest do
     HTTPoison.start()
   end
 
+  describe "setting HTTP signature" do
+    test "set http signature header" do
+      actor = insert(:actor)
+
+      signature =
+        HTTPSignatures.sign(actor, %{
+          host: "example.com",
+          "content-length": 15,
+          digest: Jason.encode!(%{id: "my_id"}) |> HTTPSignatures.build_digest(),
+          "(request-target)": HTTPSignatures.generate_request_target("POST", "/inbox"),
+          date: HTTPSignatures.generate_date_header()
+        })
+
+      assert signature =~ "headers=\"(request-target) content-length date digest host\""
+    end
+  end
+
   describe "fetching actor from it's url" do
     test "returns an actor from nickname" do
       use_cassette "activity_pub/fetch_tcit@framapiaf.org" do