Broadcasting

Question

Could anyone please provide me with the code or link to send and receive broadcast messages if possible using UDP?

I have been stuck in a problem and hope if u guys could help me resolve it. Thanks

Answer 1

Here's a C# example:

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;

class MainClass {
    static void Main(string[] args)
    {
        ThreadPool.QueueUserWorkItem(StartUDPListener);

        UdpClient udpClient = new UdpClient();
        udpClient.Send(new byte[]{0x00}, 1, new IPEndPoint(IPAddress.Broadcast, 4567));

        Console.ReadLine();
   }

   private static void StartUDPListener(object state) {
       UdpClient udpServer = new UdpClient(new IPEndPoint(IPAddress.Broadcast, 4567));

       IPEndPoint remoteEndPoint = null;
       udpServer.Receive(ref remoteEndPoint);

       Console.WriteLine("UDP broadcast received from " + remoteEndPoint + ".");   
   }
}

Answer 2

Here is example code for both the broadcast sender and receiver.

It should be easily portable to any language which has access to the standard Berkly Sockets API.

#!/usr/bin/perl -w
# broadcast sender script
use strict;
use diagnostics;
use Socket;

my $sock;
my $receiverPort = 9722;
my $senderPort = 9721;

socket($sock, PF_INET, SOCK_DGRAM, getprotobyname('udp'))   || die "socket: $!";
setsockopt($sock, SOL_SOCKET, SO_REUSEADDR, pack("l", 1))   || die "setsockopt: $!";
setsockopt($sock, SOL_SOCKET, SO_BROADCAST, pack("l", 1)) or die "sockopt: $!";
bind($sock, sockaddr_in($senderPort, inet_aton('192.168.2.103')))  || die "bind: $!";

while (1) {
    my $datastring = `date`;
    my $bytes = send($sock, $datastring, 0, 
                     sockaddr_in($receiverPort, inet_aton('192.168.2.255')));
    if (!defined($bytes)) { 
        print("$!\n"); 
    } else { 
        print("sent $bytes bytes\n"); 
    }
    sleep(2);
}

#!/usr/bin/perl -w
# broadcast receiver script
use strict;
use diagnostics;
use Socket;

my $sock;

socket($sock, PF_INET, SOCK_DGRAM, getprotobyname('udp'))   || die "socket: $!";
setsockopt($sock, SOL_SOCKET, SO_REUSEADDR, pack("l", 1))   || die "setsockopt: $!";
bind($sock, sockaddr_in(9722, inet_aton('192.168.2.255')))  || die "bind: $!"; 

# just loop forever listening for packets
while (1) {
    my $datastring = '';
    my $hispaddr = recv($sock, $datastring, 64, 0); # blocking recv
    if (!defined($hispaddr)) {
        print("recv failed: $!\n");
        next;
    }
    print "$datastring";
}