go-bbs/main.go

package main

import (
	"bufio"
	"flag"
	"io"
	"log"
	"net"
	"os/exec"
	"strconv"
	"sync"
	"time"

	"github.com/xtaci/gaio"
)

func main() {
	port := flag.Int("port", 3333, "Port to accept connections on.")
	host := flag.String("host", "127.0.0.1", "Host or IP to bind to")
	flag.Parse()

	w, err := gaio.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}
	defer w.Close()

	l, err := net.Listen("tcp", *host+":"+strconv.Itoa(*port))
	if err != nil {
		log.Panicln(err)
	}
	log.Println("Listening to connections at '"+*host+"' on port", strconv.Itoa(*port))
	defer l.Close()

	for {
		conn, err := l.Accept()
		if err != nil {
			log.Panicln(err)
		}

		log.Println("new client", conn.RemoteAddr())

		// set up io channel for this connection
		chIO := make(chan gaio.OpResult)

		// submit the first async write IO request
		err = (chIO, conn, welcomeHandler())
		if err != nil {
            log.Printf("err sending welcomeHandler: %v\n", err)
			return
		}
		// hand off channel to menuHandler
		menuHandler(chIO, conn, *w)
	}
}

func menuHandler(chIO chan gaio.OpResult, c net.Conn, w gaio.Watcher) {
	log.Printf("Connection received: %s", c.RemoteAddr())

	// watcher.WaitIO goroutine
	go func() {
		for {
			results, err := w.WaitIO()
			if err != nil {
				log.Println(err)
				return
			}

			for _, res := range results {
				chIO <- res
			}
		}
	}()

	// send welcome banner
	if err := welcomeHandler(&c); err != nil {
		log.Printf("error sending welcomeHandler on initial connect: %v", err)
	}

	wg := new(sync.WaitGroup)

	wg.Add(1)
	go func() {
		defer wg.Done()
		scanner := bufio.NewScanner(c)
		scanner.Split(bufio.ScanLines)

		for scanner.Scan() {
			line := scanner.Bytes()

			log.Printf("Menu received line: %v (%v)", line, string(line))
			switch string(line) {
			case "welcome":
				if err := welcomeHandler(&c); err != nil {
					log.Printf("error sending welcomeHandler from cmd `welcome`: %v", err)
				}
			case "adventure":
				// start the door and wait
				log.Printf("starting door handler...")
				if err := doorHandler(&c); err != nil {
					log.Printf("error from cmd `adventure`: %v", err)
				}
				log.Printf("returning from door")
				n, err := c.Write([]byte("\n\n> "))
				if err != nil {
					log.Printf("error writing to connection: %v", err)
				} else {
					log.Printf("wrote %d byte prompt to connection", n)
				}
			case "exit":
				if err := exitHandler(c); err != nil {
					log.Printf("error sending exitHandler from cmd `exit`: %v", err)
				}
			default:
				n, err := c.Write([]byte("huh?\n\n> "))
				if err != nil {
					log.Printf("error writing to connection: %v", err)
				} else {
					log.Printf("wrote %d bytes to connection", n)
				}
			}
		}
	}()

	time.Sleep(time.Millisecond)
	wg.Wait()
	log.Printf("Goodbye %s!", c.RemoteAddr())
}

func sendClientText(c net.Conn, s string) error {
	n, err := c.Write([]byte(s))
	if err != nil { //	svr.ListenAndServe()

		log.Printf("error writing to connection: %v", err)
		return err
	} else {
		log.Printf("wrote %d bytes to connection", n)
	}
	return nil
}

func welcomeHandler(c *net.Conn) error {
	const bannerText = "\x1b[2J\x1b[H\x1b[31m\x1b[J\r\n" + `

    _       __     _ ` + "" + `
   | |     / /__  / /________  ____ ___  ___` + "" + `
   | | /| / / _ \/ / ___/ __ \/ __ '__ \/ _ \` + "" + `
   | |/ |/ /  __/ / /__/ /_/ / / / / / /  __/` + "" + `
   |__/|__/\___/_/\___/\____/_/ /_/ /_/\___/` + "\r\n\x1b[33m" + `
                __` + "" + `
               / /_____ ` + "" + `
              / __/ __ \` + "" + `
             / /_/ /_/ /` + "" + `
             \__/\____/` + "\x1b[35m\r\n" + `
                    _    __` + "" + `
                   | |  / /__  _____________` + "" + `
                   | | / / _ \/ ___/ ___/ _ \` + "" + `
                   | |/ /  __/ /  (__  )  __/` + "" + `
                   |___/\___/_/  /____/\___/` + "\x1b[37m\r\n" + `
                          _____ __            ___` + "" + `
                         / ___// /___  ______/ (_)___  _____` + "" + `
                         \__ \/ __/ / / / __  / / __ \/ ___/` + "" + `
                        ___/ / /_/ /_/ / /_/ / / /_/ (__  ) ` + "" + `
                       /____/\__/\__,_/\__,_/_/\____/____/  ` + "\x1b[32m\r\n\r\n\r\n" + `
   Help is available: type help` + "\r\n\r\n> "
	err := sendClientText(*c, bannerText)
	if err != nil {
		log.Printf("error writing to connection: %v", err)
	}
	return nil
}

func exitHandler(c net.Conn) error {
	const exitMessage = "\x1b[2J\x1b[H\x1b[31m\x1b[J\r\n" + `

      ___|                                                                                  |                 | 
    \___ \   _ \  _ \  |   |  _ \  |   |     __| __ \   _' |  __|  _ \   __|  _ \\ \  \   / __ \   _ \  |   | | 
          |  __/  __/  |   | (   | |   |   \__ \ |   | (   | (     __/  (    (   |\ \  \ /  |   | (   | |   |_| 
    _____/ \___|\___| \__, |\___/ \__,_| ) ____/ .__/ \__,_|\___|\___| \___|\___/  \_/\_/  _.__/ \___/ \__, |_) 
                      ____/             /       _|                                                     ____/    


`
	err := sendClientText(c, exitMessage)
	if err != nil {
		log.Printf("error writing to connection: %v", err)
	}
	time.Sleep(500 * time.Millisecond)

	return c.Close()
}

func doorHandler(c *net.Conn) error {
	const bannerText = "\r\nCOLOSSAL CAVE\r\n\r\n"
	err := sendClientText(*c, bannerText)
	if err != nil {
		log.Printf("error writing to connection: %v\n", err)
	}

	cmd := exec.Command("/usr/games/adventure")

	stdout, _ := cmd.StdoutPipe()
	stdin, _ := cmd.StdinPipe()

	cmd.Start()
	Terminator := make(chan bool)
	wg := new(sync.WaitGroup)
	wg.Add(1)
	go func(c net.Conn, Terminator *chan bool, wg *sync.WaitGroup) {
		log.Println("starting stdin reader goroutine")
		defer wg.Done()
	Check:
		for {
			select {
			case <-*Terminator:
				break Check
			default:
				time.Sleep(time.Second)
				inBuf := make([]byte, 80)
				var l int
				if l, err = c.Read(inBuf); err != nil {
					if err == io.EOF {
						log.Println("connection closed?")
						break Check
					} else {
						log.Printf("error reading conn: %v\n", err)
						break Check
					}
				}
				if l > 0 {
					log.Printf("writing %d bytes to stdin: %v\n", l, string(inBuf[:l]))
					stdin.Write(inBuf[:l])
				}
			}
		}
		log.Println("exiting stdin reader goroutine")
	}(*c, &Terminator, wg)

	log.Println("starting stdout reader goroutine")
	scanner := bufio.NewScanner(stdout)
	scanner.Split(bufio.ScanLines)

	for scanner.Scan() {
		m := scanner.Bytes()
		(*c).Write(m)
		(*c).Write([]byte{'\n'})
		log.Printf("wrote %d bytes to stdout: %v\n", len(m)+1, string(m))
	}
	log.Println("exiting stdout reader goroutine")
	Terminator <- true

	log.Println("waiting for wg")
	wg.Wait()
	log.Println("waiting for cmd")
	exitErr := cmd.Wait()
	if exitErr != nil {
		log.Printf("cmd exited with err: %v\n", exitErr)
	}
	return nil
}