Implement packet type checking and get back up to speed

apps/amethyst/lib/apps/connection_handler.ex

@@ -87,7 +87,7 @@ alias ElixirSense.Log
           if is_map(newstate) do
             newstate
           else
-            Logger.warning("State change to #{newstate} is not a map! Did you forget to return :ok?")
+            Logger.warning("State change to #{inspect(newstate)} is not a map! Did you forget to return :ok?")
             state
           end
       end
@@ -100,9 +100,15 @@ alias ElixirSense.Log
   end
 
   defp send_packet(socket, connstate, packet, version) do
+    try do
       data = connstate.serialize(packet, version)
       length = byte_size(data) |> Amethyst.Minecraft.Write.varint()
       :gen_tcp.send(socket, length <> data)
+    rescue
+      e ->
+        Logger.error("Error sending packet #{inspect(packet)} in state #{connstate}: #{Exception.format(:error, e, __STACKTRACE__)}")
+        send(self(), {:disconnect, "§cError sending packet #{inspect(packet)}:\n#{Exception.format(:error, e, __STACKTRACE__)}"})
+    end
   end
 
   defp disconnect(socket, reason, connstate, version) do

apps/amethyst/lib/nbt.ex

@@ -27,6 +27,20 @@ defmodule Amethyst.NBT.Write do
     <<type_id(type)::size(8), payload(type, value)::binary>>
   end
 
+  def check_type({:byte, value}) when is_integer(value) and value in -128..127, do: true
+  def check_type({:short, value}) when is_integer(value) and value in -32_768..32_767, do: true
+  def check_type({:int, value}) when is_integer(value) and value in -2_147_483_648..2_147_483_647, do: true
+  def check_type({:long, value}) when is_integer(value) and value in -9_223_372_036_854_775_808..9_223_372_036_854_775_807, do: true
+  def check_type({:float, value}) when is_float(value), do: true
+  def check_type({:double, value}) when is_float(value), do: true
+  def check_type({:byte_array, values}) when is_list(values), do: Enum.all?(values, &is_integer/1)
+  def check_type({:string, value}) when is_binary(value), do: true
+  def check_type({:list, {type, values}}) when is_list(values), do: Enum.all?(values, &check_type({type, &1}))
+  def check_type({:compound, values}) when is_map(values), do: Enum.all?(values, fn {name, {type, value}} -> check_type({type, value}) end)
+  def check_type({:int_array, values}) when is_list(values), do: Enum.all?(values, &is_integer/1)
+  def check_type({:long_array, values}) when is_list(values), do: Enum.all?(values, &is_integer/1)
+  def check_type(_), do: false
+
   defp type_id(:end), do: 0
   defp type_id(:byte), do: 1
   defp type_id(:short), do: 2

apps/amethyst/lib/states/configuration.ex

@@ -61,7 +61,7 @@ defmodule Amethyst.ConnectionState.Configuration do
   ]
   Macros.defpacket_clientbound :clientbound_known_packs, 0x0E, 767, [
     packs: {:array, [
-      nameshape: :string,
+      namespace: :string,
       id: :string,
       version: :string
     ]}
@@ -269,8 +269,9 @@ defmodule Amethyst.ConnectionState.Configuration do
     send(self(), {:set_state, Amethyst.ConnectionState.Play})
     game = Application.fetch_env!(:amethyst, :default_game) |> Amethyst.GameCoordinator.find_or_create()
     state = state |> Map.put(:game, game)
-    if Amethyst.Api.Game.login(game, state) == :reject do
+    if Amethyst.API.Game.login(game, state) == :reject do
       send(self(), {:disconnect, "Default game rejected connection"})
+      :ok
     else
       send(self(), {:send_packet, %{
         packet_type: :login,
@@ -294,6 +295,7 @@ defmodule Amethyst.ConnectionState.Configuration do
         portal_cooldown: 0,
         enforces_secure_chat: false
       }})
+      state
     end
   end
 

apps/amethyst/lib/states/macros.ex

@@ -15,6 +15,7 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 defmodule Amethyst.ConnectionState.Macros do
+  require Logger
   defmacro defpacket_serverbound(name, id, version, signature) do
     quote do
       def deserialize(unquote(id), unquote(version), data) do
@@ -27,7 +28,11 @@ defmodule Amethyst.ConnectionState.Macros do
   defmacro defpacket_clientbound(name, id, version, signature) do
     quote do
       def serialize(%{packet_type: unquote(name)} = packet, unquote(version)) do
+        if Amethyst.ConnectionState.Macros.check_type(packet, unquote(signature)) do
           Amethyst.Minecraft.Write.varint(unquote(id)) <> Amethyst.ConnectionState.Macros.write_signature(packet, unquote(signature))
+        else
+          raise "Invalid packet type for #{unquote(name)}! Got #{inspect(packet)}"
+        end
       end
     end
   end
@@ -56,11 +61,15 @@ defmodule Amethyst.ConnectionState.Macros do
           end
         {:array, signature} ->
           {[count], rest} = Read.start(rest) |> Read.varint() |> Read.stop()
+          if count == 0 do
+            {[[] | acc], rest, :reversed}
+          else
             {items, rest} = Enum.reduce(1..count, {[], rest}, fn _, {acc, rest} ->
                 {item, rest} = read_signature(rest, signature)
                 {[item | acc], rest}
             end)
             {[Enum.reverse(items) | acc], rest, :reversed}
+          end
         t -> apply(Read, t, [{acc, rest, :reversed}])
       end
     end) |> Read.stop()
@@ -91,4 +100,56 @@ defmodule Amethyst.ConnectionState.Macros do
       end
     end)
   end
+
+  def check_type(packet, signature) do
+    try do
+      Enum.all?(signature, fn {name, type} ->
+        case Map.get(packet, name, :missing) do
+          :missing -> throw {:missing, name}
+          value -> case type_matches(value, type) do
+            true -> true
+            false -> throw {:mismatch, name, value, type}
+          end
+        end
+      end)
+    catch
+      reason ->
+        Logger.debug("Found invalid packet type: #{inspect(reason)}")
+        false
+    end
+  end
+
+  def type_matches(value, :bool) when is_boolean(value), do: true
+  def type_matches(value, :byte) when is_integer(value) and value in -128..127, do: true
+  def type_matches(value, :ubyte) when is_integer(value) and value in 0..255, do: true
+  def type_matches(value, :short) when is_integer(value) and value in -32768..32767, do: true
+  def type_matches(value, :ushort) when is_integer(value) and value in 0..65535, do: true
+  def type_matches(value, :int) when is_integer(value) and value in -2147483648..2147483647, do: true
+  def type_matches(value, :long) when is_integer(value) and value in -9223372036854775808..9223372036854775807, do: true
+  def type_matches(value, :float) when is_float(value), do: true
+  def type_matches(value, :double) when is_float(value), do: true
+  def type_matches(value, :varint) when is_integer(value) and value in -2147483648..2147483647, do: true
+  def type_matches(value, :varlong) when is_integer(value) and value in -9223372036854775808..9223372036854775807, do: true
+  def type_matches(value, :uuid) when is_binary(value) and byte_size(value) == 36, do: true
+  def type_matches(value, :string) when is_binary(value), do: true
+  def type_matches(value, :raw) when is_binary(value), do: true
+  def type_matches(value, :byte_array) when is_binary(value), do: true
+  def type_matches({x, y, z}, :position) when
+          is_integer(x) and x in -33554432..33554431 and
+          is_integer(y) and y in -2048..2047 and
+          is_integer(z) and z in -33554432..33554431, do: true
+  def type_matches(value, :nbt), do: Amethyst.NBT.Write.check_type(value)
+  def type_matches(value, :json) do
+    case Jason.encode(value) do
+      {:ok, _} -> true
+      _ -> false
+    end
+  end
+  def type_matches(value, {:optional, type}) when is_nil(value), do: true
+  def type_matches(value, {:optional, type}), do: type_matches(value, type)
+  def type_matches(value, {:array, signature}) when is_list(value), do: Enum.all?(value, fn item -> check_type(item, signature) end)
+  def type_matches(value, {:compound, signature}) when is_map(value), do: check_type(value, signature)
+  def type_matches(_, _) do
+    false
+  end
 end