FreeBSD SCTP support?

Michael Tuexen Michael.Tuexen at
Wed Aug 11 06:30:55 UTC 2010

On Aug 11, 2010, at 3:40 AM, Sebastien Decugis wrote:

> Hello,
> I am encountering a problem with SCTP stack in FreeBSD 8.1 release (on
> amd64); and I am looking for the correct place to report a bug. Would
> someone from this list be kind enough to give me direction where I
> should report the problem? I am totally new to FreeBSD and I was not
> able to find a better place than this mailing-list so far...
Reporting it here is the correct place.
> If by any change this list is the correct place, you can find the
> description of the problem and steps to reproduce here:
It was reported here yesterday and I responded already...
> As I understand the answer in that bug report, SCTP is not part of
> FreeBSD? But I did not install anything special, nor could find a
> dedicated place on the Internet so far...
SCTP is part of FreeBSD. But the point is that your problem is not
related to a bug in FreeBSD but in your application. If you use

/* Send a message on a socket and a particular stream */
void send_on_stream(int sock, unsigned int strid, unsigned char * msg, size_t sz)
	struct msghdr mhdr;
	struct iovec  iov;
	struct cmsghdr *cmsg;
	struct sctp_sndrcvinfo *info;
	char buffer[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
	ssize_t ret;
	memset(&mhdr, 0, sizeof(mhdr));
	memset(&iov,  0, sizeof(iov));
	memset(buffer, 0, CMSG_SPACE(sizeof(struct sctp_sndrcvinfo)));
	/* IO Vector: message data */
	iov.iov_base = msg;
	iov.iov_len  = sz;
	/* Anciliary data: specify SCTP stream */
	cmsg = (struct cmsghdr *)buffer;
	cmsg->cmsg_level = IPPROTO_SCTP;
	cmsg->cmsg_type  = SCTP_SNDRCV;
	cmsg->cmsg_len   = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));

	info = (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);
	info->sinfo_stream = strid;

	mhdr.msg_iov    = &iov;
	mhdr.msg_iovlen = 1;

	mhdr.msg_control    = buffer;
	mhdr.msg_controllen = cmsg->cmsg_len;

	if ( (ret = sendmsg(sock, &mhdr, 0)) < 0) {
		exit (1);
	ASSERT( ret == sz ); /* There should not be partial delivery with sendmsg... */

the problem is solved. You were not using the CMSG stuff correctly, so on
64-bit platforms the problem showed up.

I hope this helps, if not, feel free to ask any question or contact me directly.

BTW: Do you have a running implementation of RFC 3436 which supports multiple

Best regards
> Thank you!
> Best regards,
> Sebastien.
> -- 
> Sebastien Decugis
> Research fellow
> Network Architecture Group
> NICT (
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