This adds option-parsing code to processing of Acks in the listening state
on request_socks on the server, serving two purposes
(i) resolves a FIXME (removed);
(ii) paves the way for feature-negotiation during connection-setup.
There is an intended subtlety here with regard to dccp_check_req:
Parsing options happens only after testing whether the received packet is
a retransmitted Request. Otherwise, if the Request contained (a possibly
large number of) feature-negotiation options, recomputing state would have to
happen each time a retransmitted Request arrives, which opens the door to an
easy DoS attack. Since in a genuine retransmission the options should not be
different from the original, reusing the already computed state seems better.
The other point is - if there are timestamp options on the Request, they will
not be answered; which means that in the presence of retransmission (likely
due to loss and/or other problems), the use of Request/Response RTT sampling
is suspended, so that startup problems here do not propagate.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
8109616e2e