Very Computer

I've been trying, without success, to get one machine to send a UDP
broadcast and another machine on the network to read it.  I can get the
two machines to talk to each other via UDP when one is sending messages
directly to the other (not broadcasting).  I can also see the packets on
the receiver machine using snoop.

I would have thought something similar to the following would have
worked..

Broadcaster:

char buffer[80];
int send_size, optval = 1;
union sock
{
      struct sockaddr s;
      struct sockaddr_in i;

Quote:}    remote_addr;

setsockopt (sd, SOL_SOCKET, SO_BROADCAST, (const void *) &optval,
sizeof(optval));

remote_addr.i.sin_family = AF_INET;
remote_addr.i.sin_port = htons (PORT_NUMER);
remote_addr.i.sin_addr.s_addr = inet_addr ("###.###.###.255");

/* While you don't have to call connect for UDP, doing so allows you */
/* to send packets without specifying the IP address with each send. */

connect (sd, &remote_addr.s, sizeof(struct sockaddr));

send_size = sprintf (buffer, "Whatever");
send (sd, buffer, send_size, 0);

Receiver

sd = socket (AF_INET, SOCK_DGRAM, 0);

local_addr.i.sin_family = AF_INET;
local_addr.i.sin_port = htons (PORT_NUMBER);
local_addr.i.sin_addr.s_addr = htonl (INADDR_BROADCAST);

bind (sd,  &local_addr.s, sizeof (struct sockaddr));

remote_addr.i.sin_family = AF_INET;
remote_addr.i.sin_port = htons (PORT_NUMER);
remote_addr.i.sin_addr.s_addr = inet_addr (BROADCASTERS_IP_ADDR);

connect (sd, &remote_addr.s, sizeof(struct sockaddr));

recv (sd, buffer, size, 0);

Any ideas why this doesn't work?  Can anyone provide source that does
work?

Did you try not to call connect() but to use recvfrom() for the receiver
instead?

Michael.

Keith schrieb:

Quote:> I've been trying, without success, to get one machine to send a UDP
> broadcast and another machine on the network to read it.  I can get
> the two machines to talk to each other via UDP when one is sending
> messages directly to the other (not broadcasting).  I can also see the
> packets on the receiver machine using snoop.

> I would have thought something similar to the following would have
> worked..

> Broadcaster:

> char buffer[80];
> int send_size, optval = 1;
> union sock
> {
>       struct sockaddr s;
>       struct sockaddr_in i;
> }    remote_addr;

> sd = socket (AF_INET, SOCK_DGRAM, 0);

> setsockopt (sd, SOL_SOCKET, SO_BROADCAST, (const void *) &optval,
> sizeof(optval));

> remote_addr.i.sin_family = AF_INET;
> remote_addr.i.sin_port = htons (PORT_NUMER);
> remote_addr.i.sin_addr.s_addr = inet_addr ("###.###.###.255");

> /* While you don't have to call connect for UDP, doing so allows you
> */
> /* to send packets without specifying the IP address with each send.
> */

> connect (sd, &remote_addr.s, sizeof(struct sockaddr));

> send_size = sprintf (buffer, "Whatever");
> send (sd, buffer, send_size, 0);

> Receiver

> sd = socket (AF_INET, SOCK_DGRAM, 0);

> local_addr.i.sin_family = AF_INET;
> local_addr.i.sin_port = htons (PORT_NUMBER);
> local_addr.i.sin_addr.s_addr = htonl (INADDR_BROADCAST);

> bind (sd,  &local_addr.s, sizeof (struct sockaddr));

> remote_addr.i.sin_family = AF_INET;
> remote_addr.i.sin_port = htons (PORT_NUMER);
> remote_addr.i.sin_addr.s_addr = inet_addr (BROADCASTERS_IP_ADDR);

> connect (sd, &remote_addr.s, sizeof(struct sockaddr));

> recv (sd, buffer, size, 0);

> Any ideas why this doesn't work?  Can anyone provide source that does
> work?

--
                Fletcher Glenn