Tor Hidden (TCP) Service Example in Golang

client.go

package main

import (
	"log"
	"os"
	"strings"

	"golang.org/x/net/proxy"
)

func main() {
	args := os.Args[1:]
	if len(args) != 2 {
		log.Fatalf("usage: %s toraddress hidserviceaddress", os.Args[0])
	}
	torAddress, serviceAddress := args[0], args[1]

	dialer, err := proxy.SOCKS5("tcp", torAddress, nil, proxy.Direct)
	if err != nil {
		log.Fatal(err)
	}

	conn, err := dialer.Dial("tcp", serviceAddress)
	if err != nil {
		log.Fatal(err)
	}
	defer conn.Close()

	_, err = conn.Write([]byte("PING"))
	if err != nil {
		log.Fatal(err)
	}

	var reply [4]byte
	_, err = conn.Read(reply[:])
	if err != nil {
		log.Fatal(err)
	}
	if strings.ToUpper(string(reply[:])) != "PONG" {
		log.Fatal("received unknown reply:", reply)
	}

	log.Println("Connection Works!")
}

server.go

package main

import (
	"log"
	"net"
	"os"
	"strings"
)

func handleConnection(conn net.Conn) {
	defer conn.Close()
	var request [4]byte
	_, err := conn.Read(request[:])
	if err != nil {
		log.Println("error while reading from conn:", err)
		return
	}
	if strings.ToUpper(string(request[:])) != "PING" {
		log.Println("received unknown request:", request)
		return
	}
	conn.Write([]byte("PONG"))
	log.Println("Succesfull ping received")
}

func main() {
	args := os.Args[1:]
	if len(args) != 1 {
		log.Fatalf("usage: %s serveraddress", os.Args[0])
	}
	address := args[0]

	ln, err := net.Listen("tcp", address)
	if err != nil {
		log.Fatal(err)
	}
	for {
		conn, err := ln.Accept()
		if err != nil {
			log.Fatal(err)
		}
		go handleConnection(conn)
	}
}