client.go

package main

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

func main() {
	var conn [257]net.Conn
	var err error
	for i := 0; i < 257; i++ {
		addr := "127.0.0.1:" + strconv.Itoa(9000+i)
		conn[i], err = net.Dial("udp", addr)
		if err != nil {
			fmt.Printf("Dial error %v", err)
			return
		}
		defer conn[i].Close()
	}
	fmt.Printf("Starting readers...")
	for i := 0; i < 256; i++ {
		go reader(conn[i], i, conn[256])
	}
	fmt.Printf("Done.\n")
	fmt.Printf("Initializing connections...")
	for i := 0; i < 256; i++ {
		fmt.Fprintf(conn[i], "")
	}
	fmt.Printf("Done.\n")
	fmt.Printf("Sending start signal...")
	fmt.Fprintf(conn[256], "")
	fmt.Printf("Done.\n")
	fmt.Printf("Receiving file...")
	outFile, _ := os.Create("testfile")
	outFile.Close()
	p :=  make([]byte, 1)
	// Wait for server to send end of file signal
	_, _ = bufio.NewReader(conn[256]).Read(p)
	fmt.Printf("Complete!\n")
	return
}

func reader(conn net.Conn, val int, nextConn net.Conn) {
	for {
		p :=  make([]byte, 1)
		_, err := bufio.NewReader(conn).Read(p)
		if err == nil {
			writer(byte(val))
		}
		// Send signal for next byte
		fmt.Fprintf(nextConn, "")
	}
}

func writer(v byte) {
	val := make([]byte, 1)
	val[0] = v
	outFile, _ := os.OpenFile("testfile",os.O_APPEND|os.O_WRONLY,0666)
	_, _ = outFile.Write(val)
	outFile.Close()
}