Golang golang-tcp (snippet)

Go programming example 'golang-tcp'

golang-tcp

Golang beginners example: golang-tcp

package main

import (
    "bufio"
    "fmt"
    "io"
    "log"
    "net"
    "time"
)

const retrytime = 510 * time.Millisecond

func tcpClient(str, addr string) string {
    return tcpClientHelper(str, addr, 3)
}

func tcpClientHelper(str, addr string, retry int) string {
    tcpAddr, err := net.ResolveTCPAddr("tcp", addr)
    conn, err := net.DialTCP("tcp4", nil, tcpAddr)
    if err == nil {
        defer conn.Close()

        payloadBytes := []byte(fmt.Sprintf("%s\r\n\r\n", str))
        if _, err = conn.Write(payloadBytes); err != nil {
            log.Println(err)

            if retry > 0 {
                time.Sleep(retrytime)
                return tcpClientHelper(str, addr, retry-1)
            }
        }
        bytes := make([]byte, 65535)
        _, err := bufio.NewReader(conn).Read(bytes)
        if err == nil || err == io.EOF {
            return string(bytes)
        }
        return fmt.Sprint(err)
    }
    log.Println(err)

    if retry > 0 {
        time.Sleep(retrytime)
        return tcpClientHelper(str, addr, retry-1)
    }
    return ""
}

func main() {
    var host string = "google.de"
    var port string = "80"
    var request string = "GET /index.html"

    response := tcpClient(request, host+":"+port)
    fmt.Printf("response from %v:%v for the request \"%v\" is: \n%v\n", host, port, request, response)
}

Useful links

• Learn Go: https://golangr.com
• Download Go: https://golang.org