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Re: Cannot sendto multicast using FreeBSD stack
- From: Andrew Lunn <andrew at lunn dot ch>
- To: Chad Handrich <chandric at weldtechcorp dot com>
- Cc: ecos-discuss at ecos dot sourceware dot org
- Date: Thu, 10 Jan 2008 15:53:20 +0100
- Subject: Re: [ECOS] Cannot sendto multicast using FreeBSD stack
- References: <47862BB1.2030409@weldtechcorp.com>
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
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