GOST Relay Protocol

Zero-dependency Go implementation of the GOST relay wire protocol (v1). Used by go-gost/gost for relay tunnel communication.

Install

go get github.com/go-gost/relay

Protocol

Fixed 4-byte header, version always 0x01.

Request:   | VER(1) | CMD/FLAGS(1) | FEALEN(2) | FEATURES(VAR) |
Response:  | VER(1) | STATUS(1)    | FEALEN(2) | FEATURES(VAR) |

Commands

Constant	Value	Purpose
CmdConnect	0x01	TCP forward
CmdBind	0x02	Bind listener
CmdAssociate	0x03	UDP associate

Features

Each feature has a 3-byte header: TYPE(1) + LEN(2) + DATA(VAR).

Type	Payload
FeatureUserAuth (0x01)	Username/password for authentication
FeatureAddr (0x02)	Target address (IPv4, IPv6, or domain + port)
FeatureTunnel (0x03)	20-byte tunnel/connector ID
FeatureNetwork (0x04)	2-byte network type (TCP, UDP, IP, Unix, Serial)

Usage

package main

import (
    "bytes"
    "net"

    "github.com/go-gost/relay"
)

func main() {
    // Build a request
    req := &relay.Request{
        Version: relay.Version1,
        Cmd:     relay.CmdConnect,
        Features: []relay.Feature{
            &relay.UserAuthFeature{Username: "user", Password: "pass"},
            &relay.AddrFeature{AType: relay.AddrDomain, Host: "example.com", Port: 443},
            &relay.NetworkFeature{Network: relay.NetworkTCP},
        },
    }

    // Write to a connection
    conn, _ := net.Dial("tcp", "relay-server:8421")
    req.WriteTo(conn)

    // Read the response
    var resp relay.Response
    resp.ReadFrom(conn)
}

AddrFeature from string

var f relay.AddrFeature
f.ParseFrom("example.com:8080") // auto-detects IPv4/IPv6/domain

TunnelID / ConnectorID

Both are 20-byte value types with UUID-format string output:

tid := relay.NewTunnelID(uuidBytes)         // standard
tid := relay.NewPrivateTunnelID(uuidBytes)  // sets private flag (0x80)
tid.String() // "abababab-abab-abab-abab-abababababab"

cid := relay.NewConnectorID(uuidBytes)
cid := relay.NewUDPConnectorID(uuidBytes)   // sets UDP flag (0x01)

All setter methods (SetPrivate, SetUDP, SetWeight) return a new value — they do not mutate the receiver.

License

MIT