Enable Websocket support for Minecraft Java. Since most CDN providers(at least for their free tier) do not support raw TCP proxy, with the help of this mod, the owner can now hide the server behind a CDN and let the players connect via WebSocket, thus preventing DDoS attacks.

For Minecraft Forge, Neoforge and Fabric:

• 1.20.5, 1.20.6, 1.21, 1.21.1, 1.21.2, 1.21.3, 1.21.4
• 1.20.2, 1.20.3, 1.20.4
• 1.20.1
• 1.18.2, 1.19.x, 1.20

This branch is for 1.20.5 and above.

This mod runs standalone and does not have any dependency.

• The server would allow players to connect via WebSocket.
• Players can still join using vanilla TCP.
• The server accepts and handles TCP and WebSocket connections on the same listening port.
• Without installing this mod on the client side, a player can still join a server that has this mod using vanilla TCP.
• The server can acquire client statistics (e.g., real IP) from the WebSocket handshake..

• The client can join WebSocket-enabled servers using URI like ws://hostname.com:port/path_to_minecraft_endpoint.
• The client can join any servers using vanilla TCP using the old syntax, e.g. hostname_or_ip:port.

• This mod does not affect any gameplay.
• This mod does not modify any GUI.
• Vanilla clients can join your server even if you install this mod, note that other mods you have may prevent vanilla clients from joining.
• Installing this mod on your client does not prevent you from joining other vanilla or mod servers.
• The server can still get the real IP of the players who joined via CDN-proxied WebSocket.
• This mod is compatible with other TCP-WebSocket proxies, such as websocat.

Sometimes the DNS returns a slow IP for the HTTP hostname (ws) or the SNI (wss). The client may want to control how to resolve the IP address.

The client can optionally control the HTTP hostname and the SNI used during WebSocket handshake:

Insecure WebSocket connection with http hostname specified:
ws://host.com@ip.ip.ip.ip

Specify sni and http hostname to the same value(sni-host.com), resolve server IP from ip.ip.ip.ip:
wss://sni-host.com@ip.ip.ip.ip

Set sni and http hostname differently, resolve server IP from host.com:
wss://sni.com:@host.com[:port]

Set sni and http hostname differently, resolve server IP from sni.com:
wss://:host.com@sni.com[:port]

Set sni, http hostname, and the server address seperately
wss://sni.com:host.com@ip.ip.ip.ip

Port and path specification can be appended at the same time.

The configuration of this mod is passed in the "system properties". You can use -D in the JVM command line to pass such options.

• netty-codec-http for handling HTTP and WebSocket

You need to install Fabric Loader and then install this mod. Fabric API is optional but highly recommended.

To modify and debug the code, first import the "forge" or "fabric" folder as a Gradle project in Eclipse IDE, and then run the gradle task genEclipseRuns.

Windows users need to replace ./ and ../ with .\ and ..\, respectively.

The codebase uses Minecraft official mapping.

On the server side, if a client joins via WebSocket, its handshake request can be accessed via the vanilla net.minecraft.network.Connection class. To obtain such information, cast a Connection instance into IConnectionEx, then calls IConnectionEx.getWsHandshakeRequest().

This is useful for obtaining information about the original request if the Minecraft server is behind a reverse proxy (e.g. a CDN). For example, header X-Forwarded-For and CF-IPCountry indicate the client IP address and the client country code, respectively.

git clone https://github.com/rikka0w0/wsmc.git
cd wsmc/fabric
./gradlew build

To debug in Fabric, one may need to create run/config/fabric_loader_dependencies.json with the following content:

{
  "version": 1,
  "overrides": {
    "wsmc": {
      "-depends": {
        "minecraft": "IGNORED",
        "fabricloader": "IGNORED"
      }
    }
  }
} 

git clone https://github.com/rikka0w0/wsmc.git
cd wsmc/forge
./gradlew build

./gradlew -Dorg.gradle.java.home=/path_to_jdk_directory <commands>

• Since 1.18.1, Minecraft requires Java 17
• Since 1.20.5, Minecraft requires Java 21