From 1d741d785a55af202878755f2490a7dcf7755278 Mon Sep 17 00:00:00 2001
From: Kodi Craft <kodi@kdcf.me>
Date: Mon, 8 Jul 2024 17:59:44 +0200
Subject: [PATCH] "Implement" "login"

---
 config/runtime.exs     |  3 ++-
 lib/data.ex            |  7 +++++++
 lib/servers/generic.ex | 10 +++++++---
 lib/servers/login.ex   | 16 ++++++++++++++--
 4 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/config/runtime.exs b/config/runtime.exs
index 3cd9ca6..7ef1357 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -1,4 +1,5 @@
 import Config
 
 config :amethyst,
-  port: 25599 # Bogus port for testing, avoids unexpected conflicts
+  port: 25599, # Bogus port for testing, avoids unexpected conflicts
+  encryption: false
diff --git a/lib/data.ex b/lib/data.ex
index 37afc44..a927731 100644
--- a/lib/data.ex
+++ b/lib/data.ex
@@ -26,6 +26,13 @@ defmodule Amethyst.Minecraft.Write do
     UUID.string_to_binary!(uuid)
   end
 
+  def bool(value) do
+    case value do
+      true -> <<0x01::8>>
+      false -> <<0x00::8>>
+    end
+  end
+
   def varint(value) when value in -2_147_483_648..2_147_483_647 do
     <<value::32-unsigned>> = <<value::32-signed>> # This is a trick to allow the arithmetic shift to act as a logical shift
     varnum("", value)
diff --git a/lib/servers/generic.ex b/lib/servers/generic.ex
index 5731a0a..3acfe60 100644
--- a/lib/servers/generic.ex
+++ b/lib/servers/generic.ex
@@ -24,9 +24,13 @@ defmodule Amethyst.Server.Generic do
 
   def get_packet(client) do
     {[length], ""} = get_varint(client, "")
-    {:ok, full_packet} = :gen_tcp.recv(client, length)
-    {[id], data} = Read.start(full_packet) |> Read.varint() |> Read.stop()
-    {id, data}
+    recv = :gen_tcp.recv(client, length)
+    case recv do
+      {:ok, full_packet} -> ({[id], data} = Read.start(full_packet) |> Read.varint() |> Read.stop()
+                            {id, data})
+      {:error, :closed} -> raise RuntimeError, "TODO: Handle disconnections reasonably"
+      {:error, error} -> raise RuntimeError, "An error has occured while waiting on a packet: #{error}"
+    end
   end
 
   defp get_varint(client, acc) do
diff --git a/lib/servers/login.ex b/lib/servers/login.ex
index cade3ce..0cff919 100644
--- a/lib/servers/login.ex
+++ b/lib/servers/login.ex
@@ -72,7 +72,7 @@ defmodule Amethyst.Server.Login do
   end
   # Encryption Request https://wiki.vg/Protocol#Encryption_Request
   def serialize({:encryption_request, id, pubkey, verify_token, auth}) do
-    Write.varint(0x01) <> Write.string(id) <> Write.varint(byte_size(pubkey)) <> pubkey <> Write.varint(byte_size(verify_token)) <> verify_token <> <<auth::8>>
+    Write.varint(0x01) <> Write.string(id) <> Write.varint(byte_size(pubkey)) <> pubkey <> Write.varint(byte_size(verify_token)) <> verify_token <> Write.bool(auth)
   end
   # Login Success https://wiki.vg/Protocol#Login_Success
   def serialize({:login_success, uuid, username, props, strict}) do
@@ -80,7 +80,7 @@ defmodule Amethyst.Server.Login do
     Enum.reduce(props, "", fn {name, value, signature}, acc -> acc <> Write.string(name) <> Write.string(value) <> case signature do
       nil -> <<0x00>>
       signature -> <<0x01>> <> Write.string(signature)
-    end end) <> <<strict::8>>
+    end end) <> Write.bool(strict)
   end
   # Set Compression https://wiki.vg/Protocol#Set_Compression
   def serialize({:set_compression, threshold}) do
@@ -99,6 +99,18 @@ defmodule Amethyst.Server.Login do
   end
 
   ## HANDLING
+  # Login Start https://wiki.vg/Protocol#Login_Start
+  def handle({:login_start, name, uuid}, client) do
+    Logger.info("Logging in #{name} (#{uuid})")
+    if Application.fetch_env!(:amethyst, :encryption) do
+      raise RuntimeError, "Encryption is not currently supported!"
+    else
+      transmit({:login_success, uuid, name, [], false}, client)
+    end
+  end
+  def handle({:login_acknowledged}, _client) do
+    raise RuntimeError, "Configuration stage is not implemented."
+  end
   def handle(tuple, _) do
     Logger.error("Unhandled but known packet #{elem(tuple, 0)}")
   end