Hello,
As you'll notice I'm new to this. I want to read/write to/from
multicast adresses. I've followed the examples from Multicast-HOWTO, but I
must be missing something. I'm sending/receiving from the same host (don't
have access to another one yet) and I've tried LOOP on and LOOP off. There
are no assertion fails, but the receiver never gets anything.
These are the send and receive routines:
SEND routine
----------------------------------------------------------
#include <assert.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(void)
{ struct sockaddr_in da, la;
int ss;
unsigned char loop = 1, ttl=1;
int r;
da.sin_family = AF_INET;
da.sin_port = htons (5004);
r = inet_aton ("224.168.1.1", &(da.sin_addr));
assert (r>=0);
la.sin_family = AF_INET;
la.sin_port = htons (5004);
r = inet_aton ("192.168.1.1", &(la.sin_addr));
assert (r>=0);
/* send configuration */
ss = socket(AF_INET, SOCK_DGRAM, 0);
assert (ss>=0);
r = connect (ss, (struct sockaddr*)&da, sizeof(da));
assert (r>=0);
r = setsockopt (ss, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop));
assert (r>=0);
r = setsockopt (ss, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
assert (r>=0);
r = setsockopt (ss, IPPROTO_IP, IP_MULTICAST_IF, &(la.sin_addr),
sizeof(la.sin_addr));
assert (r>=0);
send (ss, "Msg one\0", 8, 0);
send (ss, "Msg two\0", 8, 0);
send (ss, "Msg three\0", 10, 0);
send (ss, "Msg four\0", 9, 0);
send (ss, "Msg five\0", 9, 0);
close (ss);
return (0);
}
-------------------------------------------------------------
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RECEIVE routine
--------------------------------------------------------------
#include <assert.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
int main(void)
{ struct sockaddr_in da, la;
struct ip_mreq mr;
int rs, r, n;
unsigned char msg[100];
da.sin_family = AF_INET;
da.sin_port = htons (5004);
r = inet_aton ("224.168.1.1", &(da.sin_addr));
assert (r>=0);
la.sin_family = AF_INET;
la.sin_port = htons (5004);
r = inet_aton ("192.168.1.1", &(la.sin_addr));
assert (r>=0);
/* recv configuration */
rs = socket(AF_INET, SOCK_DGRAM, 0);
assert (rs>=0);
r = bind (rs, (struct sockaddr*)&la, sizeof(la));
assert (r>=0);
r = connect (rs, (struct sockaddr*)&da, sizeof(da));
assert (r>=0);
mr.imr_multiaddr.s_addr = da.sin_addr.s_addr;
mr.imr_interface.s_addr = la.sin_addr.s_addr;
r = setsockopt (rs, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mr, sizeof(mr));
assert (r>=0);
n = 0;
while (n<4) {
r = recv (rs, msg, 100, 0);
printf ("MSG: %s\n", msg);
n++;
}
}
*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
I run the receive routine, switch to another terminal and run the send
routine. Send routine finishes, but receive routine never get anything.
Any hints?
Thank you.
--------------
Matias Freytes
Laboratorio de Comunicaciones Digitales
Universidad Nacional de Cordoba
Argentina
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