Re: [Lksctp-developers] [PATCH] SCTP: drop SACK if ctsn is not less than the next tsn of assoc
From: Neil Horman <nhorman@tuxdriver.com>
Date: 2007-08-01 11:20:26
On Wed, Aug 01, 2007 at 11:01:21AM +0200, Michael Tuexen wrote:
Hi Wei, see my comments in-line. Best regards Michael <snip >quoted
(*1) At this point ctsn_ack_point=0,next_tsn=2, ctsn=1, SACK is accept. After accept SACK, ctsn_ack_point=1. (*2) At this point ctsn_ack_point=1,next_tsn=6, ctsn=5,TSN_lt(ctsn, ctsn_ack_point) is ture, so accept SACK, and then ctsn_ack_point=5 (*3) At this point SACK is a dup SACK, ctsn_ack_point=5,next_tsn=6, ctsn=1000,TSN_lt(ctsn, ctsn_ack_point) is ture, so accept SACK, and then ctsn_ack_point=1000I would not consider it a duplicate SACK. RFC 4460, section 2.37.2 says that an implementation SHOULD abort the association when receiving a SACK acknowledging unsent data. So I would suggest to send an ABORT chunk.
+1. I didn't notice the ctsn value before. We can't safely accept that a peer pre-acks data we haven't sent. Too many security holes. Neil -- /*************************************************** *Neil Horman *Software Engineer *Red Hat, Inc. *nhorman@tuxdriver.com *gpg keyid: 1024D / 0x92A74FA1 *http://pgp.mit.edu ***************************************************/