On Tue, 28 Mar 2000, Jeff Kann wrote:
> You need to join the multicast groups in order to receive the multicast
> traffic for that group (unless you run the machine as a multicast router).
> To join/leave a mcast group, use IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP
> socket options and pass ip_mreq structure as its parameter.
I'm using IP_ADD_MEMBERSHIP in the receive routine, it's the last
setsockopt (), just after initializing structure ip_mreq. Do I need it
anywhere else?
>
> Jeff
>
> On Tue, 28 Mar 2000, Matias Freytes wrote:
>
> - 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);
> - }
> - -------------------------------------------------------------
> -
> - =*=*=*=*=*=*=*=*=*==*=*=*=*=*=*=*=*=*=*==*=*=*==*=*=*=*=*=*=*=*==*
> -
> - 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
> -
> -
> - -
> - To unsubscribe from this list: send the line "unsubscribe linux-net" in
> - the body of a message to [EMAIL PROTECTED]
> -
>
>
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