README.md

hlmux

Multiplexer for Half-Life games (and its mods)

hlmux is a gateway of multiple upstream GoldSource servers, offering a mechanism to redirect a client among these upstreams.

⚠ THIS PROJECT IS STILL UNDER CONSTRUCTION.

Usage

hlmux is a Go package, and theoretically it's just a building block for a gateway application.

hlmuxd

For convenience, we offer an official gateway application hlmuxd to ease most users' pains. It also serves as an example to demonstrate the usage of hlmux.

• Compilation

mkdir -p ./bin
go build -o ./bin ./cmd/hlmuxd

• Sample configuration (config.json)

{
    "bind": "0.0.0.0:27015",
    "api": "0.0.0.0:27081",
    "ttl": "30",
    "upstreams": [
        {
            "name": "cs1",
            "address": "10.1.80.51:27001",
            "default": true
        },
        {
            "name": "cs2",
            "address": "10.1.80.51:27002"
        }
    ]
}

• Running

./bin/hlmuxd -config config.json

# or without compilation
go run ./cmd/hlmuxd -config config.json

How does it work?

Valve has banned connect command for a long time (related issue) as a part of admin slowhacking mitigation. Many redirection plugins does not work any more, while they do serve as practical components, especially in community servers.

This project implements a gateway in front of multiple GoldSource game servers, so that the gateway can have its own decision on the traffic forwarding. After in-game plugins tell the gateway which nexthop the clients want, their traffic will be forwarded to the target server when they send handshakes next time.

The client side command retry is able to invoke re-handshaking (which is different from reconnect). Unfortunately, we have known that Valve's page is out of date by inspecting hw.so (or hw.dll on Windows) as shown below: retry is also banned, regardless of the value of cl_filterstuffcmd.

Good news is that there is still an approach to trick the clients into a state similar to a manually-issued retry. This is a sequential diagram of hlmux.