devip: tcp: Don't respond to FIN-less ACKs during TIME-WAIT (thanks Barret Rhoden)

Under the normal close sequence, when we receive a FIN|ACK, we enter
TIME-WAIT and respond to that LAST-ACK with an ACK.  Our TCP stack would
send an ACK in response to *any* ACK, which included FIN|ACK but also
included regular ACKs.  (Or PSH|ACKs, which is what we were actually
getting/sending).

That was more ACKs than is necessary and results in an endless ACK storm
if we were under the simultaneous close sequence.  In that scenario,
both sides of a connection are in TIME-WAIT.  Both sides receive
FIN|ACK, and both respond with an ACK.  Then both sides receive *those*
ACKs, and respond again.  This continues until the TIME-WAIT wait period
elapses and each side's TCP timers (in the Plan 9 / Akaros case) shut
down.

The fix for this is to only respond to a FIN|ACK when we are in TIME-WAIT.

0 files changed, 0 insertions, 0 deletions