According to ip(7) you should use setsockopt, the following works for me
(PS: I'm running 2.4.3 and I get EPERM as non root and EINVAL as root
when running your code.)
#include <net/if.h>
#include <netinet/in.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netdb.h>
#define ASSERT(a, op, b, m...) do { if ( a op b) { \
fprintf(stderr, "ASSERT (" #a " " #op " " #b ") at %s line %d:",
__FILE__, __LINE__); \
fprintf(stderr, m);\
fprintf(stderr, "\n"); \
fflush(stderr); exit(-1); }} while(0)
struct ifreq ir;
struct ip_mreq mr;
int createmcast()
{
int s, rc;
struct hostent * he;
struct sockaddr_in to;
s = socket(AF_INET, SOCK_DGRAM, 0);
ASSERT (s, == , -1, "socket failed errno=%d", errno);
mr.imr_interface.s_addr = (in_addr_t) htonl(INADDR_ANY);
to.sin_family = AF_INET;
to.sin_port = 0;
to.sin_addr.s_addr = htonl(INADDR_ANY);
// bind(s, &to, sizeof(struct sockaddr_in));
he = gethostbyname("172.16.0.116");
ASSERT (he, ==, NULL, "gethostbyname if failed %d", h_errno);
// memcpy (&mr.imr_interface, &he->h_addr_list[0], sizeof (struct
sockaddr_in));
he = gethostbyname("225.0.0.100");
ASSERT (he, ==, NULL, "gethostbyname mc failed %d", h_errno);
memcpy (&mr.imr_multiaddr, he->h_addr_list[0], sizeof (struct
sockaddr_in));
errno = 0;
printf ("%#x %#x\n", mr.imr_multiaddr.s_addr,
mr.imr_interface.s_addr);
rc = setsockopt (s, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mr, sizeof(struct
ip_mreq));
ASSERT (rc, <, 0, "setsockopt (.., IPPROTO_IP, IP_ADD_MEMBERSHIP, ..)
failed errno=%d", errno);
rc = setsockopt (s, IPPROTO_IP, IP_MULTICAST_IF, &mr.imr_interface,
sizeof(struct in_addr));
ASSERT (rc, <, 0, "setsockopt (.., IPPROTO_IP, IP_MULTICAST_IF, ..)
failed errno=%d", errno);
return s;
};
int createudp()
{
int s, rc;
struct sockaddr_in to;
s = socket(AF_INET, SOCK_DGRAM, 0);
to.sin_family = AF_INET;
to.sin_port = htons(12345);
to.sin_addr.s_addr = htonl(INADDR_ANY);
rc = bind(s, &to, sizeof(struct sockaddr_in));
ASSERT (rc, ==, -1, "bind failed %d", errno);
return s;
};
int sendmcast (int s, char * payload, int plen)
{
int rc;
struct sockaddr_in to;
to.sin_family = AF_INET;
to.sin_port = htons(12345);
memcpy(&to.sin_addr, &mr.imr_multiaddr.s_addr, sizeof(struct
in_addr));
if (plen == 0) plen = strlen(payload);
rc = sendto (s, payload, plen , 0, &to, sizeof(struct sockaddr_in));
printf ("sendto returned %d\n", rc);
ASSERT (rc, <, 0, "snndto () failed errno=%d", errno);
};
char * getdgram(int s)
{
struct sockaddr_in from;
int rc;
static char buffer[1024];
static char addrbuf[100];
socklen_t fromlen;
fromlen = sizeof(struct sockaddr_in);
rc = recvfrom(s, buffer, 1024, 0, &from, &fromlen);
inet_ntop(AF_INET, &from.sin_addr, addrbuf, 100);
printf ("from socket %d, we got a message %s sender %s:%d (%d)\n",
s, buffer, addrbuf , ntohs(from.sin_port), fromlen);
return buffer;
};
main()
{
int ms, us;
int rc;
ms = createmcast();
us = createudp();
sendmcast(us, "heihei", 0);
sleep(3);
getdgram(us);
exit(0);
// rc = ioctl (s, SIOCGIFADDR, &ir);
//ASSERT (rc, <, 0, "ioctl failed errno=%d", errno);
};
Den 28 Aug 2001 22:56:10 +0200, skrev Peter Enderborg:
> Im trying to grab some ethernet multicasts. And the ioctl that should do
> that is SIOCADDMULTI.
> But I can't get it to work. And I have not found any who use that from
> userlevel so
> this is my guess who to do it. (I don't work but dont gives any error
> message)
>
>
> #include <stdio.h>
> #include <sys/ioctl.h>
> #include <net/if.h>
> #include <arpa/inet.h>
> #include <errno.h>
> #include <sys/un.h>
>
> int main()
> {
> int i,res,sock,from_len;
> struct sockaddr_in eb_addr,from_addr;
> char databuf[1500];
> struct ifreq req;
>
>
> if((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
> {
> printf("%s",strerror(errno));
> exit(1);
> }
>
> eb_addr.sin_family = AF_INET;
> /* eb_addr.sin_family = AF_UNSPEC; */
> eb_addr.sin_addr.s_addr = inet_addr("0.0.0.0");
> eb_addr.sin_port = htons(4711);
>
> for (i = 0; i < 8; ++i)
> eb_addr.sin_zero[i] = 0;
> if(bind(sock,(struct sockaddr*) &eb_addr, sizeof(struct sockaddr_in))
> == -1)
> {
> printf("Unable to bind the socket\n");
> exit(1);
> }
> strcpy(req.ifr_name,"eth0");
> req.ifr_ifru.ifru_addr.sa_data[0] = 0x01;
> req.ifr_ifru.ifru_addr.sa_data[1] = 0x80;
> req.ifr_ifru.ifru_addr.sa_data[2] = 0xc2;
> req.ifr_ifru.ifru_addr.sa_data[3] = 0x00;
> req.ifr_ifru.ifru_addr.sa_data[4] = 0x00;
> req.ifr_ifru.ifru_addr.sa_data[5] = 0x00;
> /* req.ifr_flags = IFF_ALLMULTI; | IFF_PROMISC; */
> res = ioctl(sock,SIOCADDMULTI,&req);
> if(res == -1)
> {
> printf("%s",strerror(errno));
> exit(1);
> }
>
> while (1)
> {
> printf("enter recvfrom\n");
> res = recvfrom(sock, databuf, sizeof(databuf), 0,(struct
> sockaddr*) &from_addr, &from_len);
> printf("Received %d bytes\n", res );
> }
> return 0;
> }
>
> This on a 2.4.9 kernel on SMP P2. Im trying to grab some 802 bridge
> packets and I see them
> with tcpdump but that is using a other interface. (BPF or what ever) Any
> ideas whats wrong ?
>
>
> -
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-- _________________________________________________________________________Terje Eggestad terje.eggestad@scali.no Scali Scalable Linux Systems http://www.scali.com
Olaf Helsets Vei 6 tel: +47 22 62 89 61 (OFFICE) P.O.Box 70 Bogerud +47 975 31 574 (MOBILE) N-0621 Oslo fax: +47 22 62 89 51 NORWAY _________________________________________________________________________
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Aug 31 2001 - 21:00:32 EST