tcp: accecn: AccECN option ceb/cep and ACE field multi-wrap heuristics

tcp: accecn: AccECN option ceb/cep and ACE field multi-wrap heuristics

The AccECN option ceb/cep heuristic algorithm is from AccECN spec
Appendix A.2.2 to mitigate against false ACE field overflows. Armed
with ceb delta from option, delivered bytes, and delivered packets it
is possible to estimate how many times ACE field wrapped.

This calculation is necessary only if more than one wrap is possible.
Without SACK, delivered bytes and packets are not always trustworthy in
which case TCP falls back to the simpler no-or-all wraps ceb algorithm.

Signed-off-by: Ilpo Järvinen <ij@kernel.org>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250916082434.100722-10-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>