client-message

name	client-message
description	Implement Thistle Tea CMSG_* client messages following our architecture patterns. Use this when asked to implement a new message or you need to use one that isn't implemented yet.

Create/modify a module under lib/game/network/message/ that:

• use ThistleTea.Game.Network.ClientMessage, :CMSG_FOO
• defines a defstruct matching the fields decoded from the payload
• implements from_binary/1 using little-endian bit syntax patterns like <<x::little-size(32)>>
• implements handle/2 to update state and send any responses

Quick examples

Minimal payload (CMSG_PING):

defmodule ThistleTea.Game.Network.Message.CmsgPing do
  @moduledoc false
  use ThistleTea.Game.Network.ClientMessage, :CMSG_PING

  defstruct [:sequence_id, :latency]

  @impl ClientMessage
  def handle(%__MODULE__{sequence_id: sequence_id, latency: latency}, state) do
    Network.send_packet(%Message.SmsgPong{sequence_id: sequence_id})
    Map.put(state, :latency, latency)
  end

  @impl ClientMessage
  def from_binary(payload) do
    <<sequence_id::little-size(32), latency::little-size(32)>> = payload

    %__MODULE__{
      sequence_id: sequence_id,
      latency: latency
    }
  end
end

Payload with strings (CMSG_MESSAGECHAT):

def from_binary(payload) do
  <<chat_type::little-size(32), language::little-size(32), rest::binary>> = payload
  {:ok, message, _rest} = BinaryUtils.parse_string(rest)

  %__MODULE__{
    chat_type: chat_type,
    language: language,
    message: message
  }
end

How to find the packet spec

• Packet formats are cataloged in the wow_messages git submodule at refs/wow_messages/.
• Look up the .wowm spec here: refs/wow_messages/wow_message_parser/wowm/*/${CMSG_NAME}.wowm.
• Thistle Tea is a Vanilla (patch 1.12.1) server, so ignore future client versions.
• The refs/mangos/ directory contains the Mangos C++ server codebase and can be used as a reference for expected handle/2 behavior.

Workflow

• Translate the .wowm fields into defstruct fields and a decoder in from_binary/1.
• Use pattern matching in the function head for type safety: handle(%__MODULE__{} = msg, state).
• Register the new handler in lib/game/network/packet.ex under the @l map so packets dispatch correctly.