switch-lan-play

Make you and your friends play games like in a LAN.

                     Internet
                        |
                  [SOCKS5 Proxy] (optional)
                        |
        ARP,IPv4        |          LAN Packets
Switch <-------->  PC(lan-play)  <-------------> Server
                                       UDP

NOTE:

• This project is in an early stage. The protocol may change frequently.
• The Internet part is WIP.

Usage

To play with your friends, you and your friends should run lan-play connecting to the same Server on your PC, and set static IP on your Switch.

Your PC and Switch should be connected to the same router.

Windows Client

1. Download and install WinPcap from https://www.winpcap.org/install/default.htm

2. Download lan-play.exe from https://github.com/spacemeowx2/switch-lan-play/releases

3. Run lan-play.exe with paramter --relay-server-addr. For example:

lan-play.exe --relay-server-addr example.com:11451

After that, you may see the list like below:

1. en0 (No description available)
        IP: [192.168.1.100]
2. p2p0 (No description available)
        IP: []
Enter the interface number (1-2):

Select the interface which is in the same LAN with your Switch.

Switch

1. Go to your Switch settings page, set the IP address to static. The IP address can be any from 10.13.0.1 to 10.13.255.254, excepting 10.13.37.1. But don't use the same IP address with your friend.

   IP Address	10.13.?.?
   Subnet Mask	255.255.0.0
   Gateway	10.13.37.1

2. Click save. Press B. Switch may not be able to connect to the Internet and refuse to connect to this setting, but it doesn't matter.

3. Launch your game, hold L+R+LStick to enter lan-play mode, Switch will try to connect the no Internet setting. Host or join a game, enjoy!

Server

git clone https://github.com/spacemeowx2/switch-lan-play.git
cd switch-lan-play/server
npm install
npm run build
npm run server

Build

Debug or Release

cmake -DCMAKE_BUILD_TYPE=Debug .. cmake -DCMAKE_BUILD_TYPE=Release ..

Ubuntu / Debian

This project depends on libpcap and libuv, you can install libpcap0.8-dev and libuv1-dev on Ubuntu or Debian:

sudo apt install libpcap0.8-dev libuv1-dev

Prepare a cmake, gcc, and run like this:

mkdir build
cd build
cmake ..
make

Windows

Use MSYS2 to compile.

pacman -Sy
pacman -S mingw-w64-x86_64-gcc \
    mingw-w64-x86_64-cmake \
    mingw-w64-x86_64-make

Open MSYS2 MinGW 64-bit.

mkdir build
cd build
cmake -G "MSYS Makefiles" ..
make

Mac OS

brew install cmake libpcap libuv

mkdir build
cd build
cmake ..
make

Server

cd server
npm install
npm run build # build ts to js, only run it when code changed.
npm start

The server will listen to port 11451/udp,

Protocol

The protocol is very simple now, but I'm going to add some fileds to calculate network quality(packet loss, ping), like timestamp, seq_id, etc.

struct packet {
    uint8_t type;
    uint8_t payload[packet_len - 1];
};

enum type {
    KEEPALIVE = 0,
    IPV4 = 1,
};

The server can read IP addresses from payload and save source IP -> LAN IP to a cache table. If target ip address shown in payload doesn't hit the cache, broadcast this packet to the entire room(now a server is a room).