Add dummy server example.

/examples/dummy-client

/examples/dummy-server

// Usage (in torrc):

//   BridgeRelay 1

//   ORPort 9001

//   ExtORPort 6669

//   ServerTransportPlugin dummy exec dummy-server

package main

import (

	"io"

	"net"

	"os"

	"os/signal"

	"sync"

	"syscall"

)

import "git.torproject.org/pluggable-transports/websocket.git/src/pt"

var ptInfo pt.ServerInfo

// When a connection handler starts, +1 is written to this channel; when it

// ends, -1 is written.

var handlerChan = make(chan int)

func copyLoop(a, b net.Conn) {

	var wg sync.WaitGroup

	wg.Add(2)

	go func() {

		io.Copy(b, a)

		wg.Done()

	}()

	go func() {

		io.Copy(a, b)

		wg.Done()

	}()

	wg.Wait()

}

func handleConnection(conn net.Conn) {

	handlerChan <- 1

	defer func() {

		handlerChan <- -1

	}()

	or, err := pt.ConnectOr(&ptInfo, conn, "dummy")

	if err != nil {

		return

	}

	copyLoop(conn, or)

}

func acceptLoop(ln net.Listener) error {

	for {

		conn, err := ln.Accept()

		if err != nil {

			return err

		}

		go handleConnection(conn)

	}

	return nil

}

func startListener(addr *net.TCPAddr) (net.Listener, error) {

	ln, err := net.ListenTCP("tcp", addr)

	if err != nil {

		return nil, err

	}

	go acceptLoop(ln)

	return ln, nil

}

func main() {

	ptInfo = pt.ServerSetup([]string{"dummy"})

	listeners := make([]net.Listener, 0)

	for _, bindAddr := range ptInfo.BindAddrs {

		ln, err := startListener(bindAddr.Addr)

		if err != nil {

			pt.SmethodError(bindAddr.MethodName, err.Error())

			continue

		}

		pt.Smethod(bindAddr.MethodName, ln.Addr())

		listeners = append(listeners, ln)

	}

	pt.SmethodsDone()

	var numHandlers int = 0

	var sig os.Signal

	sigChan := make(chan os.Signal, 1)

	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)

	// wait for first signal

	sig = nil

	for sig == nil {

		select {

		case n := <-handlerChan:

			numHandlers += n

		case sig = <-sigChan:

		}

	}

	for _, ln := range listeners {

		ln.Close()

	}

	if sig == syscall.SIGTERM {

		return

	}

	// wait for second signal or no more handlers

	sig = nil

	for sig == nil && numHandlers != 0 {

		select {

		case n := <-handlerChan:

			numHandlers += n

		case sig = <-sigChan:

		}

	}

}