golang-exercises/query-cpu/cmd/server.go

/*
Copyright © 2024 Raul
*/
package cmd

import (
	"bufio"
	"fmt"
	"log"
	"net"
	"os"
	"strings"
	"time"

	"github.com/spf13/cobra"
)

// serverCmd represents the server command
var serverCmd = &cobra.Command{
	Use:   "server",
	Short: "Start the server (default port: 8080)",
	Long: `A longer description that spans multiple lines and likely contains examples
and usage of using your command. For example:

Cobra is a CLI library for Go that empowers applications.
This application is a tool to generate the needed files
to quickly create a Cobra application.`,
	Run: func(cmd *cobra.Command, args []string) {
		server()
	},
}

func init() {
	rootCmd.AddCommand(serverCmd)

	// Here you will define your flags and configuration settings.

	// Cobra supports Persistent Flags which will work for this command
	// and all subcommands, e.g.:
	// serverCmd.PersistentFlags().String("foo", "", "A help for foo")

	// Cobra supports local flags which will only run when this command
	// is called directly, e.g.:
	// serverCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
}

func server() {
	ln, err := net.Listen("tcp", ":8080")
	catchErr(err)
	fmt.Println("Listening on port 8080...")
	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')
	message = strings.TrimRight(message, "\n")
	catchErr(err)
	conn_IP := getIP(conn)
	t := time.Now()
	date := fmt.Sprintf("%d-%02d-%02dT%02d:%02d:%02d", t.Year(), t.Month(), t.Day(), t.Hour(), t.Minute(), t.Second())

	final_message := fmt.Sprintf("[%v] Received connection from %v with message: %v\n", date, conn_IP, message)
	writer(final_message)
	reply_message := fmt.Sprintf("Your message was sent successfully\n")
	conn.Write([]byte(reply_message))
	fmt.Print(final_message)

}

func getIP(conn net.Conn) (IP string) {
	if addr, ok := conn.RemoteAddr().(*net.TCPAddr); ok {
		IP = fmt.Sprintf("%v", addr)
	}
	return IP
}

func catchErr(err error) (errHappened bool) {
	errHappened = false
	if err != nil {
		errHappened = true
		log.Fatalf("Error: %v\n", err)
		os.Exit(2)
	}
	return errHappened
}

func writer(logstring string) {
	file, err := os.OpenFile("./connections.log", os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0640)
	if err != nil {
		log.Fatalf("Error occurred: %v\n", err)
	}
	defer file.Close()
	file.WriteString(logstring)
}