golang-exercises/sockets/main.go

package main

import (
	"bufio"
	"fmt"
	"net"
	"os"
	"strings"
)

var LISTENING_PORT string = ":1302"

func main() {
	if len(os.Args) != 1 {
		LISTENING_PORT = ":" + os.Args[1]
	}
	ln, err := net.Listen("tcp", LISTENING_PORT)
	catchErr(err)
	fmt.Printf("Listening on port %v...\n", strings.TrimLeft(LISTENING_PORT, ":"))

	for {
		conn, err := ln.Accept()
		catchErr(err)
		go handleConn(conn)
	}
}

func handleConn(conn net.Conn) {
	defer conn.Close()

	message, err := bufio.NewReader(conn).ReadString('\n')
	catchErr(err)
	fmt.Printf("Message received: %v", string(message))
	newMsg := strings.ToUpper(message)
	conn.Write([]byte(newMsg))
}

func catchErr(err error) (errHappened bool) {
	errHappened = false
	if err != nil {
		errHappened = true
		fmt.Println(err)
		os.Exit(2)
	}
	return errHappened
}