73 lines
2.5 KiB
Elixir
73 lines
2.5 KiB
Elixir
# Amethyst - An experimental Minecraft server written in Elixir.
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# Copyright (C) 2024 KodiCraft
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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defmodule Amethyst.Server.Generic do
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@moduledoc """
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This module includes generic logic which may be used by all stages of the server, including,
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for instance, listening for packets.
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"""
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alias Amethyst.Minecraft.Read
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def get_packet(client) do
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{[length], ""} = get_varint(client, "")
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recv = :gen_tcp.recv(client, length)
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case recv do
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{:ok, full_packet} -> ({[id], data} = Read.start(full_packet) |> Read.varint() |> Read.stop()
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{id, data})
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{:error, :closed} -> raise RuntimeError, "TODO: Handle disconnections reasonably"
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{:error, error} -> raise RuntimeError, "An error has occured while waiting on a packet: #{error}"
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end
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end
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defp get_varint(client, acc) do
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{:ok, byte} = :gen_tcp.recv(client, 1)
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case byte do
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<<0::1, _::7>> -> Read.start(acc <> byte) |> Read.varint() |> Read.stop()
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<<1::1, _::7>> -> get_varint(client, acc <> byte)
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end
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end
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end
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defmodule Amethyst.Server do
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@moduledoc """
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This module includes shared boilerplate code for all stages of the server.
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"""
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require Logger
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defmacro __using__(_opts) do
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quote do
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@spec serve(:gen_tcp.socket()) :: no_return()
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def serve(client) do
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{id, data} = Amethyst.Server.Generic.get_packet(client)
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packet = deserialize(id, data)
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Logger.debug("Got packet #{inspect(packet)}")
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handle(packet, client)
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serve(client)
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end
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def transmit(packet, client) do
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Logger.debug("Transmitting #{inspect(packet)}")
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data = serialize(packet)
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length = byte_size(data) |> Amethyst.Minecraft.Write.varint()
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Logger.debug("Sending #{inspect(length <> data)}")
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:gen_tcp.send(client, length <> data)
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end
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end
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end
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end
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