Add code for verifying homeservers' signatures on API requests

lib/matrix_server/schema/event.ex

@@ -5,7 +5,6 @@ defmodule MatrixServer.Event do
 
   alias MatrixServer.{Repo, Room, Event, Account, OrderedMap, SigningServer}
 
-  @schema_meta_fields [:__meta__]
   @primary_key {:event_id, :string, []}
   schema "events" do
     field :type, :string
@@ -287,7 +286,7 @@ defmodule MatrixServer.Event do
   defp calculate_content_hash(event) do
     result =
       event
-      |> to_map()
+      |> MatrixServer.to_serializable_map()
       |> Map.drop([:unsigned, :signature, :hashes])
       |> OrderedMap.from_map()
       |> Jason.encode()
@@ -305,7 +304,7 @@ defmodule MatrixServer.Event do
   defp redact(%Event{type: type, content: content} = event) do
     redacted_event =
       event
-      |> to_map()
+      |> MatrixServer.to_serializable_map()
       |> Map.take([
         :event_id,
         :type,
@@ -347,14 +346,4 @@ defmodule MatrixServer.Event do
         "users",
         "users_default"
       ])
-
-  # https://stackoverflow.com/questions/41523762/41671211
-  def to_map(event) do
-    association_fields = event.__struct__.__schema__(:associations)
-    waste_fields = association_fields ++ @schema_meta_fields
-
-    event
-    |> Map.from_struct()
-    |> Map.drop(waste_fields)
-  end
 end

lib/matrix_server/signing_server.ex

@@ -1,8 +1,6 @@
 defmodule MatrixServer.SigningServer do
   use GenServer
 
-  alias MatrixServer.OrderedMap
-
   # TODO: only support one signing key for now.
   @signing_key_id "ed25519:1"
 
@@ -16,8 +14,8 @@ defmodule MatrixServer.SigningServer do
     GenServer.call(__MODULE__, {:sign_object, object})
   end
 
-  def get_signing_keys do
-    GenServer.call(__MODULE__, :get_signing_keys)
+  def get_signing_keys(encoded \\ false) do
+    GenServer.call(__MODULE__, {:get_signing_keys, encoded})
   end
 
   ## Implementation
@@ -35,12 +33,7 @@ defmodule MatrixServer.SigningServer do
         _from,
         %{private_key: private_key} = state
       ) do
-    ordered_map =
-      object
-      |> Map.drop([:signatures, :unsigned])
-      |> OrderedMap.from_map()
-
-    case Jason.encode(ordered_map) do
+    case MatrixServer.encode_canonical_json(object) do
       {:ok, json} ->
         signature =
           json
@@ -62,10 +55,10 @@ defmodule MatrixServer.SigningServer do
     end
   end
 
-  def handle_call(:get_signing_keys, _from, %{public_key: public_key} = state) do
-    encoded_public_key = MatrixServer.encode_unpadded_base64(public_key)
+  def handle_call({:get_signing_keys, encoded}, _from, %{public_key: public_key} = state) do
+    result = if encoded, do: MatrixServer.encode_unpadded_base64(public_key), else: public_key
 
-    {:reply, [{@signing_key_id, encoded_public_key}], state}
+    {:reply, [{@signing_key_id, result}], state}
   end
 
   # TODO: not sure if there is a better way to do this...