apps/amethyst/lib/apps/connection_handler.ex

@@ -105,7 +105,7 @@ defmodule Amethyst.ConnectionHandler do
         end
         loop(socket, connstate, version, state)
       {:send_packet, packet} ->
-        Logger.debug("Sending packet #{inspect(packet)}")
+        # Logger.debug("Sending packet #{inspect(packet)}")
         send_packet(socket, connstate, packet, version, state)
         loop(socket, connstate, version, state)
       after 0 ->
@@ -258,7 +258,6 @@ defmodule Amethyst.ConnectionHandler do
   defp send_packet(socket, connstate, packet, version, state) do
     try do
       data = connstate.serialize(packet, version)
-      Logger.debug("#{inspect(Map.get(state, :compression))}")
       container = if Map.get(state, :compression) == nil do
         # Packet ID is included in data
         Write.varint(byte_size(data)) <> data
@@ -273,7 +272,6 @@ defmodule Amethyst.ConnectionHandler do
           Write.varint(byte_size(compressed)) <> compressed
         end
       end
-      Logger.debug(inspect(container))
       encrypted = if Map.get(state, :encryption_state) == nil do
         container
       else

apps/amethyst/lib/sha1.ex

@@ -0,0 +1,26 @@
+# Amethyst - An experimental Minecraft server written in Elixir.
+# Copyright (C) 2024 KodiCraft
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+defmodule Amethyst.Minecraft.Sha1 do
+  @moduledoc """
+  This module implements the awkward non-standard hex digest hash that Minecraft uses
+  """
+  def hash(input) do
+    # this sucks but so does the fact that mojang makes me do this so it fits
+    <<number::integer-signed-size(20*8)>> = :crypto.hash(:sha, input)
+    inspect(number, base: :hex) |> String.replace("0x", "") |> String.downcase()
+  end
+end

apps/amethyst/lib/states/login.ex

@@ -97,14 +97,41 @@ defmodule Amethyst.ConnectionState.Login do
         send(self(), {:set_compression, threshold})
       end
 
-      send(self(), {:send_packet, %{
+      if Application.get_env(:amethyst, :auth, false) == false do
-        packet_type: :login_success,
+        # Don't check authentication
-        uuid: Map.get(state, :uuid),
+        send(self(), {:send_packet, %{
-        username: Map.get(state, :name),
+          packet_type: :login_success,
-        properties: [],
+          uuid: Map.get(state, :uuid),
-        strict_error_handling: true
+          username: Map.get(state, :name),
-      }})
+          properties: [],
-      :ok
+          strict_error_handling: true
+        }})
+        Map.put(state, :authenticated, false)
+      else
+        # Check authentication
+        pubkey = Amethyst.Keys.get_pub()
+        hash = Amethyst.Minecraft.Sha1.hash(secret <> pubkey)
+        url = Application.get_env(:amethyst, :session_server, "https://sessionserver.mojang.com") <> "/session/minecraft/hasJoined?username=" <>
+          Map.get(state, :name) <> "&serverId=" <> hash # I don't think we need to verify the IP in the use case of Amethyst...
+        Logger.debug(url)
+        response = Req.get!(url,
+        headers: [
+          {"user-agent", "Amethyst/1.0"}
+        ]).body
+
+        <<c1::binary-size(8), c2::binary-size(4), c3::binary-size(4), c4::binary-size(4), c5::binary>> = response["id"]
+        uuid = [c1, c2, c3, c4, c5] |> Enum.join("-")
+
+        send(self(), {:send_packet, %{
+          packet_type: :login_success,
+          uuid: uuid,
+          username: response["name"],
+          properties: response["properties"] |>
+            Enum.map(fn prop -> %{name: prop["name"], value: prop["value"], signature: Map.get(prop, "signature") |> Base.decode64!} end),
+          strict_error_handling: true
+        }})
+        Map.put(state, :authenticated, true)
+      end
     else
       raise RuntimeError, "Invalid verify token. Broken encryption?"
     end

apps/amethyst/lib/states/macros.ex

@@ -106,7 +106,7 @@ defmodule Amethyst.ConnectionState.Macros do
       Enum.all?(signature, fn {name, type} ->
         case Map.get(packet, name, :missing) do
           :missing ->
-            if elem(type, 0) == :literal do
+            if is_tuple(type) && elem(type, 0) == :literal do
               true
             else
               throw {:missing, name}

apps/amethyst/mix.exs

@@ -39,7 +39,8 @@ defmodule Amethyst.MixProject do
       {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
       {:uuid, "~> 1.1"},
       {:ex_doc, "~> 0.22", only: :dev, runtime: false},
-      {:jason, "~> 1.4"}
+      {:jason, "~> 1.4"},
+      {:req, "~> 0.5.6", runtime: true}
     ]
   end
 end

apps/amethyst/test/hash_test.exs

@@ -0,0 +1,10 @@
+defmodule Sha1Test do
+  alias Amethyst.Minecraft.Sha1
+  use ExUnit.Case, async: true
+
+  test "Mojang sha1 hash digest" do
+    assert Sha1.hash("Notch") == "4ed1f46bbe04bc756bcb17c0c7ce3e4632f06a48"
+    assert Sha1.hash("jeb_") == "-7c9d5b0044c130109a5d7b5fb5c317c02b4e28c1"
+    assert Sha1.hash("simon") == "88e16a1019277b15d58faf0541e11910eb756f6"
+  end
+end

config/runtime.exs

@@ -3,6 +3,7 @@ import Config
 config :amethyst,
   port: 25599, # Bogus port for testing, avoids unexpected conflicts
   encryption: true, # Whether or not to request encryption from clients.
-  auth: false, # Whether or not users should be authenticated with Mojang.
+  auth: true, # Whether or not users should be authenticated with Mojang.
+  session_server: "https://sessionserver.mojang.com", # Base URL to the Mojang session server
   compression: 256, # Packets larger than this amount are sent compressed. Set to nil to disable compression.
   default_game: Example.Game # Which game new players should be sent to

mix.lock

@@ -5,11 +5,19 @@
   "elixir_math": {:hex, :elixir_math, "0.1.2", "5655bdf7f34e30906f31cdcf3031b43dd522ce8d2936b60ad4696b2c752bf5c9", [:mix], [], "hexpm", "34f4e4384903097a8ec566784fa8e9aa2b741247d225741f07cc48250c2aa64c"},
   "ex_doc": {:hex, :ex_doc, "0.34.2", "13eedf3844ccdce25cfd837b99bea9ad92c4e511233199440488d217c92571e8", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "5ce5f16b41208a50106afed3de6a2ed34f4acfd65715b82a0b84b49d995f95c1"},
   "file_system": {:hex, :file_system, "1.0.1", "79e8ceaddb0416f8b8cd02a0127bdbababe7bf4a23d2a395b983c1f8b3f73edd", [:mix], [], "hexpm", "4414d1f38863ddf9120720cd976fce5bdde8e91d8283353f0e31850fa89feb9e"},
+  "finch": {:hex, :finch, "0.19.0", "c644641491ea854fc5c1bbaef36bfc764e3f08e7185e1f084e35e0672241b76d", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.6.2 or ~> 1.7", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 1.1", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "fc5324ce209125d1e2fa0fcd2634601c52a787aff1cd33ee833664a5af4ea2b6"},
+  "hpax": {:hex, :hpax, "1.0.0", "28dcf54509fe2152a3d040e4e3df5b265dcb6cb532029ecbacf4ce52caea3fd2", [:mix], [], "hexpm", "7f1314731d711e2ca5fdc7fd361296593fc2542570b3105595bb0bc6d0fad601"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
   "makeup": {:hex, :makeup, "1.1.2", "9ba8837913bdf757787e71c1581c21f9d2455f4dd04cfca785c70bbfff1a76a3", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cce1566b81fbcbd21eca8ffe808f33b221f9eee2cbc7a1706fc3da9ff18e6cac"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.16.2", "627e84b8e8bf22e60a2579dad15067c755531fea049ae26ef1020cad58fe9578", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "41193978704763f6bbe6cc2758b84909e62984c7752b3784bd3c218bb341706b"},
   "makeup_erlang": {:hex, :makeup_erlang, "1.0.1", "c7f58c120b2b5aa5fd80d540a89fdf866ed42f1f3994e4fe189abebeab610839", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "8a89a1eeccc2d798d6ea15496a6e4870b75e014d1af514b1b71fa33134f57814"},
+  "mime": {:hex, :mime, "2.0.6", "8f18486773d9b15f95f4f4f1e39b710045fa1de891fada4516559967276e4dc2", [:mix], [], "hexpm", "c9945363a6b26d747389aac3643f8e0e09d30499a138ad64fe8fd1d13d9b153e"},
+  "mint": {:hex, :mint, "1.6.2", "af6d97a4051eee4f05b5500671d47c3a67dac7386045d87a904126fd4bbcea2e", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1 or ~> 0.2.0 or ~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "5ee441dffc1892f1ae59127f74afe8fd82fda6587794278d924e4d90ea3d63f9"},
+  "nimble_options": {:hex, :nimble_options, "1.1.1", "e3a492d54d85fc3fd7c5baf411d9d2852922f66e69476317787a7b2bb000a61b", [:mix], [], "hexpm", "821b2470ca9442c4b6984882fe9bb0389371b8ddec4d45a9504f00a66f650b44"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
+  "nimble_pool": {:hex, :nimble_pool, "1.1.0", "bf9c29fbdcba3564a8b800d1eeb5a3c58f36e1e11d7b7fb2e084a643f645f06b", [:mix], [], "hexpm", "af2e4e6b34197db81f7aad230c1118eac993acc0dae6bc83bac0126d4ae0813a"},
   "pre_commit": {:hex, :pre_commit, "0.3.4", "e2850f80be8090d50ad8019ef2426039307ff5dfbe70c736ad0d4d401facf304", [:mix], [], "hexpm", "16f684ba4f1fed1cba6b19e082b0f8d696e6f1c679285fedf442296617ba5f4e"},
+  "req": {:hex, :req, "0.5.6", "8fe1eead4a085510fe3d51ad854ca8f20a622aae46e97b302f499dfb84f726ac", [:mix], [{:brotli, "~> 0.3.1", [hex: :brotli, repo: "hexpm", optional: true]}, {:ezstd, "~> 1.0", [hex: :ezstd, repo: "hexpm", optional: true]}, {:finch, "~> 0.17", [hex: :finch, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}, {:mime, "~> 2.0.6 or ~> 2.1", [hex: :mime, repo: "hexpm", optional: false]}, {:nimble_csv, "~> 1.0", [hex: :nimble_csv, repo: "hexpm", optional: true]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "cfaa8e720945d46654853de39d368f40362c2641c4b2153c886418914b372185"},
+  "telemetry": {:hex, :telemetry, "1.3.0", "fedebbae410d715cf8e7062c96a1ef32ec22e764197f70cda73d82778d61e7a2", [:rebar3], [], "hexpm", "7015fc8919dbe63764f4b4b87a95b7c0996bd539e0d499be6ec9d7f3875b79e6"},
   "uuid": {:hex, :uuid, "1.1.8", "e22fc04499de0de3ed1116b770c7737779f226ceefa0badb3592e64d5cfb4eb9", [:mix], [], "hexpm", "c790593b4c3b601f5dc2378baae7efaf5b3d73c4c6456ba85759905be792f2ac"},
 }