#20150119-03 :: go :: go를 이용한 TCP/IP Echo Server Example

아래는 go를 이용한 간단한 TCP/IP Echo Server 예제 입니다.

관리 용이성을 위해 서버와 클라이언트를 한 코드에 넣었습니다.

package main

import (

  "bufio"

  "fmt"

  "net"

  "os"

  "time"

)

func main() {

  send := make(chan string)

  quit := make(chan string)

  addr, err := net.ResolveTCPAddr("tcp", ":9000")

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

  if err != nil {

    fmt.Println(err.Error())

    return;

  }

  go runServer(ln, quit)

  time.Sleep(time.Duration(1) * time.Second)

  conn, err := net.Dial("tcp", "127.0.0.1:9000")

  if err != nil {

    fmt.Println(err.Error())

    return;

  }

  go runClient(conn, quit)

  go runScan(send, quit)

  stop := false

  for !stop {

    fmt.Println("main loop ...")

    select {

    case text, ok := <- send:

      if !ok {

        ln.Close()

        conn.Close()

        stop = true

      }

      conn.Write([]byte(text))

    case err := <- quit:

      fmt.Println(err)

      stop = true

    }

  }

  fmt.Println("complete.")

}

func runScan(send chan string, quit chan string) {

  fmt.Println("runScan begin.")

  scanner := bufio.NewScanner(os.Stdin)

  for scanner.Scan() {

    text := scanner.Text()

    if text == "." {

      close(send)

      break

    }

    send <- text

  }

  

  fmt.Println("runScan end.")

}

func runServer(ln *net.TCPListener, quit chan string) {

  fmt.Println("runServer begin.")

  for {

    conn, err := ln.Accept()

    if err != nil {

      quit <- err.Error()

      break

    }

    go runSession(conn, quit)

  }

  fmt.Println("runServer end.")

}

func runSession(conn net.Conn, quit chan string) {

  fmt.Println("runSession begin.")

  buf := make([]byte, 1024)

  for {

    size, err := conn.Read(buf)

    if err != nil || size == 0 {

      quit <- err.Error()

      break

    }

    _, err = conn.Write(buf[:size])

    if err != nil {

      quit <- err.Error()

      break

    }

  }

  fmt.Println("runSession end.")

}

func runClient(conn net.Conn, quit chan string) {

  fmt.Println("runClient begin.")

  buf := make([]byte, 1024)

  for {

    size, err := conn.Read(buf)

    if err != nil {

      quit <- err.Error()

      break

    }

    fmt.Println(string(buf[:size]))

  }

  fmt.Println("runClient end.")

}