On Wed, Sep 21, 2016 at 10:21:43AM +0000, David Laight wrote:
> From: Marcelo Ricardo Leitner
> > Sent: 20 September 2016 22:19
> > sctp_acked() is using 32bit arithmetics on 16bits vars, via TSN_lte()
> > macros, which is weird and confusing.
> >
> > Once the offset to ctsn is calculated, all wrapping is already handled
> > and thus to verify the Gap Ack blocks we can just use pure
> > less/big-or-equal than checks.
> >
> > Also, rename gap variable to tsn_offset, so it's more meaningful, as
> > it doesn't point to any gap at all.
> >
> > Even so, I don't think this discrepancy resulted in any practical bug.
>
> I think it might if gab.start/end are greater than 32767
Why? Mind sharing a case that it goes wrong?
Marcelo
>
> ...
> > - gap = tsn - ctsn;
> > - for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
> > - if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
> > - TSN_lte(gap, ntohs(frags[i].gab.end)))
> > + blocks = ntohs(sack->num_gap_ack_blocks);
> > + tsn_offset = tsn - ctsn;
> > + for (i = 0; i < blocks; ++i) {
> > + if (tsn_offset >= ntohs(frags[i].gab.start) &&
> > + tsn_offset <= ntohs(frags[i].gab.end))
> ...
>
> David
>
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