Hello all,
I am a beginner with the multicast socket, I would really appreciate a little help with the following question :
I have to network interfaces, eth0 and eth1.
I assigned no IP addresses to both of them, by using :
Code:
ifconfig eth0 0.0.0.0 up
ifconfig eth0 0.0.0.0 up
I added a bridge to forward the trafic from an interface to an other:
Code:
brctl addbr br0
brctl addif bro eth0
brctl addif bro eth1
I also created several IP aliases, to use them with the two interfaces:
Code:
ifconfig eth0:0 192.168.0.1 netmask 255.255.255.0 up
ifconfig eth1:0 192.168.1.1 netmask 255.255.255.0 up
I would like to run a sample code for udp multicasting:
Here's the sender code:
Code:
int main(int argc, char *argv[]) {
int sock; /* socket descriptor */
char send_str[MAX_LEN]; /* string to send */
struct sockaddr_in mc_addr; /* socket address structure */
unsigned int send_len; /* length of string to send */
char* mc_addr_str; /* multicast IP address */
unsigned short mc_port; /* multicast port */
unsigned char mc_ttl=1; /* time to live (hop count) */
mc_addr_str = "224.0.0.10"; /* arg 1: multicast IP address */
mc_port = 6666; /* arg 2: multicast port number */
/* create a socket for sending to the multicast address */
if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
perror("socket() failed");
exit(1);
}
/* set the TTL (time to live/hop count) for the send */
if ((setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL,
(void*) &mc_ttl, sizeof(mc_ttl))) < 0) {
perror("setsockopt() failed");
exit(1);
}
/* construct a multicast address structure */
memset(&mc_addr, 0, sizeof(mc_addr));
mc_addr.sin_family = AF_INET;
mc_addr.sin_addr.s_addr = inet_addr(mc_addr_str);
mc_addr.sin_port = htons(mc_port);
printf("Begin typing (return to send, ctrl-C to quit):\n");
/* clear send buffer */
memset(send_str, 0, sizeof(send_str));
while (fgets(send_str, MAX_LEN, stdin)) {
send_len = strlen(send_str);
/* send string to multicast address */
if ((sendto(sock, send_str, send_len, 0,
(struct sockaddr *) &mc_addr,
sizeof(mc_addr))) != send_len) {
perror("sendto() sent incorrect number of bytes");
exit(1);
}
/* clear send buffer */
memset(send_str, 0, sizeof(send_str));
}
close(sock);
exit(0);
}
Here's the receiver code:
Code:
int main(int argc, char *argv[]) {
int sock; /* socket descriptor */
int flag_on = 1; /* socket option flag */
struct sockaddr_in mc_addr; /* socket address structure */
char recv_str[MAX_LEN+1]; /* buffer to receive string */
int recv_len; /* length of string received */
struct ip_mreq mc_req; /* multicast request structure */
char* mc_addr_str; /* multicast IP address */
unsigned short mc_port; /* multicast port */
struct sockaddr_in from_addr; /* packet source */
unsigned int from_len; /* source addr length */
mc_addr_str = "224.0.0.10"; /* arg 1: multicast ip address */
mc_port = 6666; /* arg 2: multicast port number */
/* create socket to join multicast group on */
if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
perror("socket() failed");
exit(1);
}
/* set reuse port to on to allow multiple binds per host */
if ((setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flag_on,
sizeof(flag_on))) < 0) {
perror("setsockopt() failed");
exit(1);
}
/* construct a multicast address structure */
memset(&mc_addr, 0, sizeof(mc_addr));
mc_addr.sin_family = AF_INET;
mc_addr.sin_addr.s_addr = htonl(INADDR_ANY);
mc_addr.sin_port = htons(mc_port);
/* bind to multicast address to socket */
if ((bind(sock, (struct sockaddr *) &mc_addr,
sizeof(mc_addr))) < 0) {
perror("bind() failed");
exit(1);
}
/* construct an IGMP join request structure */
mc_req.imr_multiaddr.s_addr = inet_addr(mc_addr_str);
mc_req.imr_interface.s_addr = htonl(INADDR_ANY);
/* send an ADD MEMBERSHIP message via setsockopt */
if ((setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
(void*) &mc_req, sizeof(mc_req))) < 0) {
perror("setsockopt() failed");
exit(1);
}
for (;;) { /* loop forever */
/* clear the receive buffers & structs */
memset(recv_str, 0, sizeof(recv_str));
from_len = sizeof(from_addr);
memset(&from_addr, 0, from_len);
/* block waiting to receive a packet */
if ((recv_len = recvfrom(sock, recv_str, MAX_LEN, 0,
(struct sockaddr*)&from_addr, &from_len)) < 0) {
perror("recvfrom() failed");
exit(1);
}
/* output received string */
printf("Received %d bytes from %s: ", recv_len,
inet_ntoa(from_addr.sin_addr));
printf("%s", recv_str);
}
/* send a DROP MEMBERSHIP message via setsockopt */
if ((setsockopt(sock, IPPROTO_IP, IP_DROP_MEMBERSHIP,
(void*) &mc_req, sizeof(mc_req))) < 0) {
perror("setsockopt() failed");
exit(1);
}
close(sock);
}
So when I run the receiver program, here's the error that occurs:
Code:
setsockopt() failed: No such device
I didn't have any problems before switching to the bridge configuration, I'm missing something, but don't what ..
Thanks a lot for your help guys !
