Fix Mastodon WebSocket authentication

Mastodon uses the Sec-Websocket-Protocol header to send the auth token. It is not clear if this is a violation of the RFC, but Mastodon is not the first application in the wild to use this header for authentication purposes. Phoenix does not allow accessing this header, so we work around it temporarily with a minor patch to Phoenix 1.7.14. We will reach out to Phoenix to discuss how to make this use case possible.

changelog.d/mastodon-websocket.fix

@@ -0,0 +1 @@
+Fix Mastodon WebSocket authentication

lib/pleroma/web/endpoint.ex

@@ -14,6 +14,7 @@ defmodule Pleroma.Web.Endpoint do
     websocket: [
       path: "/",
       compress: false,
+      connect_info: [:sec_websocket_protocol],
       error_handler: {Pleroma.Web.MastodonAPI.WebsocketHandler, :handle_error, []},
       fullsweep_after: 20
     ]

lib/pleroma/web/mastodon_api/websocket_handler.ex

@@ -22,7 +22,7 @@ def child_spec(_opts), do: :ignore
   # This only prepares the connection and is not in the process yet
   @impl Phoenix.Socket.Transport
   def connect(%{params: params} = transport_info) do
-    with access_token <- Map.get(params, "access_token"),
+    with access_token <- find_access_token(transport_info),
          {:ok, user, oauth_token} <- authenticate_request(access_token),
          {:ok, topic} <-
            Streamer.get_topic(params["stream"], user, oauth_token, params) do
@@ -244,4 +244,13 @@ def handle_error(conn, :unauthorized) do
   def handle_error(conn, _reason) do
     Plug.Conn.send_resp(conn, 404, "Not Found")
   end
+
+  defp find_access_token(%{
+         connect_info: %{sec_websocket_protocol: [token]}
+       }),
+       do: token
+
+  defp find_access_token(%{params: %{"access_token" => token}}), do: token
+
+  defp find_access_token(_), do: nil
 end

mix.exs

@@ -132,7 +132,8 @@ defp logger_deps do
   # Type `mix help deps` for examples and options.
   defp deps do
     [
-      {:phoenix, "~> 1.7.3"},
+      {:phoenix,
+       git: "https://github.com/feld/phoenix", branch: "v1.7.14-websocket-headers", override: true},
       {:phoenix_ecto, "~> 4.4"},
       {:ecto_sql, "~> 3.10"},
       {:ecto_enum, "~> 1.4"},

mix.lock

@@ -65,7 +65,7 @@
   "httpoison": {:hex, :httpoison, "1.8.2", "9eb9c63ae289296a544842ef816a85d881d4a31f518a0fec089aaa744beae290", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "2bb350d26972e30c96e2ca74a1aaf8293d61d0742ff17f01e0279fef11599921"},
   "idna": {:hex, :idna, "6.1.1", "8a63070e9f7d0c62eb9d9fcb360a7de382448200fbbd1b106cc96d3d8099df8d", [:rebar3], [{:unicode_util_compat, "~>0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "92376eb7894412ed19ac475e4a86f7b413c1b9fbb5bd16dccd57934157944cea"},
   "inet_cidr": {:hex, :inet_cidr, "1.0.8", "d26bb7bdbdf21ae401ead2092bf2bb4bf57fe44a62f5eaa5025280720ace8a40", [:mix], [], "hexpm", "d5b26da66603bb56c933c65214c72152f0de9a6ea53618b56d63302a68f6a90e"},
-  "jason": {:hex, :jason, "1.4.3", "d3f984eeb96fe53b85d20e0b049f03e57d075b5acda3ac8d465c969a2536c17b", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "9a90e868927f7c777689baa16d86f4d0e086d968db5c05d917ccff6d443e58a3"},
+  "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
   "joken": {:hex, :joken, "2.6.0", "b9dd9b6d52e3e6fcb6c65e151ad38bf4bc286382b5b6f97079c47ade6b1bcc6a", [:mix], [{:jose, "~> 1.11.5", [hex: :jose, repo: "hexpm", optional: false]}], "hexpm", "5a95b05a71cd0b54abd35378aeb1d487a23a52c324fa7efdffc512b655b5aaa7"},
   "jose": {:hex, :jose, "1.11.6", "613fda82552128aa6fb804682e3a616f4bc15565a048dabd05b1ebd5827ed965", [:mix, :rebar3], [], "hexpm", "6275cb75504f9c1e60eeacb771adfeee4905a9e182103aa59b53fed651ff9738"},
   "jumper": {:hex, :jumper, "1.0.2", "68cdcd84472a00ac596b4e6459a41b3062d4427cbd4f1e8c8793c5b54f1406a7", [:mix], [], "hexpm", "9b7782409021e01ab3c08270e26f36eb62976a38c1aa64b2eaf6348422f165e1"},
@@ -94,7 +94,7 @@
   "open_api_spex": {:hex, :open_api_spex, "3.18.2", "8c855e83bfe8bf81603d919d6e892541eafece3720f34d1700b58024dadde247", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:poison, "~> 3.0 or ~> 4.0 or ~> 5.0", [hex: :poison, repo: "hexpm", optional: true]}, {:ymlr, "~> 2.0 or ~> 3.0 or ~> 4.0", [hex: :ymlr, repo: "hexpm", optional: true]}], "hexpm", "aa3e6dcfc0ad6a02596b2172662da21c9dd848dac145ea9e603f54e3d81b8d2b"},
   "parse_trans": {:hex, :parse_trans, "3.4.1", "6e6aa8167cb44cc8f39441d05193be6e6f4e7c2946cb2759f015f8c56b76e5ff", [:rebar3], [], "hexpm", "620a406ce75dada827b82e453c19cf06776be266f5a67cff34e1ef2cbb60e49a"},
   "pbkdf2_elixir": {:hex, :pbkdf2_elixir, "1.2.1", "9cbe354b58121075bd20eb83076900a3832324b7dd171a6895fab57b6bb2752c", [:mix], [{:comeonin, "~> 5.3", [hex: :comeonin, repo: "hexpm", optional: false]}], "hexpm", "d3b40a4a4630f0b442f19eca891fcfeeee4c40871936fed2f68e1c4faa30481f"},
-  "phoenix": {:hex, :phoenix, "1.7.14", "a7d0b3f1bc95987044ddada111e77bd7f75646a08518942c72a8440278ae7825", [:mix], [{:castore, ">= 0.0.0", [hex: :castore, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 2.1", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:phoenix_template, "~> 1.0", [hex: :phoenix_template, repo: "hexpm", optional: false]}, {:phoenix_view, "~> 2.0", [hex: :phoenix_view, repo: "hexpm", optional: true]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 2.7", [hex: :plug_cowboy, repo: "hexpm", optional: true]}, {:plug_crypto, "~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:websock_adapter, "~> 0.5.3", [hex: :websock_adapter, repo: "hexpm", optional: false]}], "hexpm", "c7859bc56cc5dfef19ecfc240775dae358cbaa530231118a9e014df392ace61a"},
+  "phoenix": {:git, "https://github.com/feld/phoenix", "fb6dc76c657422e49600896c64aab4253fceaef6", [branch: "v1.7.14-websocket-headers"]},
   "phoenix_ecto": {:hex, :phoenix_ecto, "4.4.3", "86e9878f833829c3f66da03d75254c155d91d72a201eb56ae83482328dc7ca93", [:mix], [{:ecto, "~> 3.5", [hex: :ecto, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.14.2 or ~> 3.0 or ~> 4.0", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:plug, "~> 1.9", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "d36c401206f3011fefd63d04e8ef626ec8791975d9d107f9a0817d426f61ac07"},
   "phoenix_html": {:hex, :phoenix_html, "3.3.4", "42a09fc443bbc1da37e372a5c8e6755d046f22b9b11343bf885067357da21cb3", [:mix], [{:plug, "~> 1.5", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "0249d3abec3714aff3415e7ee3d9786cb325be3151e6c4b3021502c585bf53fb"},
   "phoenix_live_dashboard": {:hex, :phoenix_live_dashboard, "0.8.3", "7ff51c9b6609470f681fbea20578dede0e548302b0c8bdf338b5a753a4f045bf", [:mix], [{:ecto, "~> 3.6.2 or ~> 3.7", [hex: :ecto, repo: "hexpm", optional: true]}, {:ecto_mysql_extras, "~> 0.5", [hex: :ecto_mysql_extras, repo: "hexpm", optional: true]}, {:ecto_psql_extras, "~> 0.7", [hex: :ecto_psql_extras, repo: "hexpm", optional: true]}, {:ecto_sqlite3_extras, "~> 1.1.7 or ~> 1.2.0", [hex: :ecto_sqlite3_extras, repo: "hexpm", optional: true]}, {:mime, "~> 1.6 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:phoenix_live_view, "~> 0.19 or ~> 1.0", [hex: :phoenix_live_view, repo: "hexpm", optional: false]}, {:telemetry_metrics, "~> 0.6 or ~> 1.0", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}], "hexpm", "f9470a0a8bae4f56430a23d42f977b5a6205fdba6559d76f932b876bfaec652d"},