go-tcp-client-server

tcp-client-server_cmds_client_main.go

package main

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

func main() {
	arguments := os.Args
	if len(arguments) < 2 {
		fmt.Println("Please provide a port number!")
		return
	}
	port := ":" + arguments[1]
	conn, err := net.Dial("tcp", "127.0.0.1"+port)
	if err != nil {
		fmt.Printf("error occurred when trying to connect to port: %s error: %s", port, err)
		return
	}
	defer conn.Close()
	reader := bufio.NewReader(os.Stdin)
	fmt.Println("Connected...")
	for {
		line, _, err := reader.ReadLine()
		if err != nil {
			fmt.Println("error while reading form stdin", err)
			return
		}
		line = append(line, '\n')
		_, err = conn.Write(line)
		if err != nil {
			fmt.Println("Writing error:", err)
			return
		}
		readLine, _, err := bufio.NewReader(conn).ReadLine()
		if err != nil {
			if err.Error() == "EOF" {
				fmt.Println("Disconnected!")
				return
			}
			fmt.Println("Error while reading from server: ", err)
			return
		}
		fmt.Printf("> %s\n", readLine)
	}
}

tcp-client-server_cmds_server_main.go

package main

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

func main() {
	arguments := os.Args

	if len(arguments) < 2 {
		fmt.Println("please provide a port number!")
		return
	}

	port := ":" + arguments[1]
	l, err := net.Listen("tcp4", port)
	if err != nil {
		fmt.Printf("error occurred when trying to listen to port: %s error: %s", port, err)
		return
	}
	defer l.Close()
	fmt.Println("Server started...")
	for {
		c, err := l.Accept()
		if err != nil {
			fmt.Println("Accept error: ", err)
			return
		}
		go handleConnection(c)
	}
}

func handleConnection(c net.Conn) {
	fmt.Printf("Serving... %s\n", c.RemoteAddr().String())
	for {
		line, _, err := bufio.NewReader(c).ReadLine()
		if err != nil {
			fmt.Println("Reader error:", err)
			fmt.Printf(`"%s"`, line)
			return
		}
		trimmedLine := strings.TrimSpace(string(line))
		fmt.Println("Received: ", trimmedLine)
		if trimmedLine == "STOP" {
			break
		}
		c.Write([]byte(fmt.Sprintf("echo: %s\n", trimmedLine)))
	}
	c.Close()
}