Andrew Lunn wrote:
On Thu, Jan 10, 2008 at 09:29:05AM -0500, Chad Handrich wrote:
Hello,
I wrote about this problem previously, but still have not found a solution
(see the subject "Problem with multicast using FreeBSD stack" from
11/29/07)
I have eCos configured with the FreeBSD stack. Everything is working
except a portion where I have to SEND multicast UDP packets using sendto().
In these instances, sendto() returns -1, and errno == EHOSTUNREACH.
Here is my test multicast code that is failing:
struct in_addr interface_addr;
// eth0 is configured to be 89.89.200.181
inet_aton("89.89.200.181", &interface_addr);
setsockopt(skt, IPPROTO_IP, IP_MULTICAST_IF, &interface_addr,
sizeof(interface_addr));
struct in_addr multi_iface;
getsockopt(skt, IPPROTO_IP, IP_MULTICAST_IF, &multi_iface,
sizeof(multi_iface));
diag_printf("getsockopt specifies %s as multicast interface\n",
inet_ntoa(multi_iface));
// This outputs the string: getsockopt specifies 89.89.200.181 as
multicast interface
// Sample data to send via multicast
char buf[5]; buf[0] = 0; buf[1] = 1; buf[2] = 2; buf[3] = 3; buf[4] = 4;
struct sockaddr_in to;
to.sin_family = AF_INET;
to.sin_port = htons(2222);
inet_aton("239.192.23.160", &(to.sin_addr));
int retval = sendto(skt, buf, 5, 0, (struct sockaddr *)&to,
sizeof(to));
diag_printf("post-sendto: errno=%d retval=%d\n", errno, retval);
// This outputs the string: post-sendto: errno=365 retval=-1
// errno=365 corresponds to EHOSTUNREACH
Any help to get this multicast sendto() to succeed would be greatly
appreciated.
Do you also add a multicast route? Typically on Linux you have to add
a route:
route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
Andrew
It appears that you are correct. Using ioctl to add a route with the
parameters you specified seems to be working. My thanks.
Chad
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