PING server using Go

ping.go

// Start using
//  go run ping.go -addr=:3141
// Query using
//  nc -u localhost 3141

package main
 
import (
    "log"
    "net"
    "flag"
    "bytes"
)

func main() {
    addr := flag.String("addr", "localhost:0", "addr")
    flag.Parse()

    // resolve address
    ServerAddr, err := net.ResolveUDPAddr("udp", *addr)
    if err != nil {
        log.Fatal("Couldn't resolve passed in addr ", err)
    }
    
    // start listening
    ServerConn, err := net.ListenUDP("udp", ServerAddr)
    if err != nil {
        log.Fatal("Couldn't listen on passed in addr " , err)
    }
    log.Println("Listening on", ServerConn.LocalAddr().String())

    // close connection as soon as program exists
    defer ServerConn.Close()

    // used for incoming messages 
    buf := make([]byte, 1024)

    PING := []byte("PING\n")
    PONG := []byte("PONG\n")
 
    for {
        n, addr, err := ServerConn.ReadFromUDP(buf)
        log.Println("Received ", string(buf[0:n]), " from ", addr)

        if err != nil {
            log.Println("Error: ", err)
        } 

        if bytes.Equal(buf[:len(PING)], PING) {
            ServerConn.WriteTo(PONG, addr)
            continue
        }
    }
}