msnet

msnet is a pure Golang networking package for MapleStory

Installation

$ go get github.com/zhyonc/msnet@latest

Quick Start

package main

import (
	"log/slog"
	"net"

	"github.com/zhyonc/msnet"
	"github.com/zhyonc/msnet/enum"
)

type server struct {
	addr string
	lis  net.Listener
}

func NewServer(addr string) *server {
	s := &server{
		addr: addr,
	}
	return s
}

func (s *server) Run() {
	lis, err := net.Listen("tcp", s.addr)
	if err != nil {
		slog.Error("Failed to create tcp listener", "err", err)
		return
	}
	slog.Info("TCPListener is starting on " + s.addr)
	s.lis = lis
	for {
		if s.lis == nil {
			slog.Warn("TCPListener is nil")
			break
		}
		conn, err := s.lis.Accept()
		if err != nil {
			slog.Error("Failed to accept conn", "err", err)
			continue
		}
		slog.Info("New client connected", "addr", conn.RemoteAddr())
		cs := msnet.NewCClientSocket(s, conn, nil, nil)
		go cs.OnRead()
		cs.OnConnect()
	}
}

func (s *server) Shutdown() {
	s.lis.Close()
	s.lis = nil
}

func main() {
	msnet.New(&msnet.Setting{
		MSRegion: enum.GMS,
		MSVersion: 95,
		MSMinorVersion: "1",
	})
	s := NewServer("127.0.0.1:8484")
	s.Run()
}

Setting

• MSRegion: MapleStory Regions including KMS(1)/KMST(2)/JMS(3)/CMS(4)/TMS(6)/MSEA(7)/GMS(8)/BMS(9)

• MSVersion: MapleStory Client Version

• MSMinorVersion: MapleStory Client Minor Version

• RecvXOR: The server must use the same XOR key to recover the original packet

• SendXOR: The client must use the same XOR key to recover the original packet

• IsXORCipher: Used in versions about 2004

• IsCycleAESKey:

  • Default is false, old AES key will be used, which is compatible with most earlier versions
  • If set true, cycle AES key will be used, which is compatible with newer versions

• CustomAESKey(optional): It's used to instead of old AES key and cycle AES key

  • Decrypt: A 32-byte array used for decrypting data in CInPacket::DecryptData
  • Encrypt: A 32-byte array used for encrypting data in COutPacket::MakeBufferList

• AESInitType(optional): Compatible with older versions based on tutorial

  • Default: Used in versions after about 2008
  • Duplicate: Used in versions about 2005~2007 (excluding TMS)
  • Shuffle: Used in TMS versions about 2005~2007

Packet

Header	AESOFB	Note
4 Bytes	Any Bytes	Except for the first packet

Decode

Decode packet length using XOR of two little-endian uint16 values from header
PacketLen = (Header[0]+Header[1]*0x100) ^ (Header[2]+Header[3]*0x100)

Encode

Encode packet length using little-endian XOR with sVersion and sendIV

• sVersion = (^clientVer >> 8 & 0xFF) | ((^clientVer << 8) & 0xFF00)
• a = int(sendIV[3])
• a |= int(sendIV[2])<<8
• a ^= sVersion
• b = ((PacketLen << 8) & 0xFF00) | (PacketLen >> 8)
• c = a ^ b
• Header = [a>>8, a, c>>8, b]

Format

Opcode	Data	Note
2 Bytes	Any Bytes	Except for the connect packet

Connect Packet

Name	PacketLen	Version	MinorVersionLen	MinorVersion	RecvIV	SendIV	Region	Note
Connect	2 Bytes	2 Bytes	2 Bytes	1 Byte	4 Bytes	4 Bytes	1 Bytes	The connect packet