TCP Socket Example in Go

tcpsock_ex.go

// go run main.go

package main

import (
	"bytes"
	"fmt"
	"net"
	"os"
	"time"
)

func listen(end chan<- bool) {
	addr, err := net.ResolveTCPAddr("tcp4", "127.0.0.1:10111")
	if err != nil {
		fmt.Printf("listen: Failed to resolve: %v\n", err)
		os.Exit(1)
	}
	lnt, err := net.ListenTCP("tcp4", addr)
	if err != nil {
		fmt.Printf("listen: Failed to listen: %v\n", err)
		os.Exit(1)
	}
	conn, err := lnt.AcceptTCP()
	if err != nil {
		fmt.Printf("listen: Failed on accept: %v\n", err)
		os.Exit(1)
	}

	// Receive message
	buf := make([]byte, 2048)
	n, err := conn.Read(buf)
	if err != nil {
		fmt.Printf("listen: Failed to read: %v\n", err)
	} else {
		fmt.Printf("listen: Received %v bytes\n  >>\t%v\n", n, string(buf))
		// Send a message back
		conn.Write(buf)
	}
	
	conn.Close()
	lnt.Close()
	end <- true
}

func dial(end chan<- bool) {
	raddr, err := net.ResolveTCPAddr("tcp4", "127.0.0.1:10111")
	if err != nil {
		fmt.Printf("dial: Failed to resolve remote: %v\n", err)
		os.Exit(1)
	}
	laddr, err := net.ResolveTCPAddr("tcp4", "127.0.0.1:0")
	if err != nil {
		fmt.Printf("dial: Failed to resolve local: %v\n", err)
		os.Exit(1)
	}
	conn, err := net.DialTCP("tcp4", laddr, raddr)
	if err != nil {
		fmt.Printf("dial: Failed to connect: %v\n", err)
		os.Exit(1)
	}

	// Send a message
	var buf bytes.Buffer
	buf.WriteString("Hello from sender")
	n, err := conn.Write(buf.Bytes())
	if err != nil {
		fmt.Printf("dial: Failed to send: %v\n", err)
	} else {
		fmt.Printf("dial: Sent %v bytes\n", n)
		rbuf := make([]byte, 2048)
		// Receive reply
		n, _ = conn.Read(rbuf)
		fmt.Printf("dial: Received: %v\n", string(rbuf[:n]))
	}

	conn.Close()
	end <- true
}

func main() {
	end := make(chan bool, 2)
	go listen(end)
	time.Sleep(time.Second)
	go dial(end)
	<-end
	<-end
}