TCP: Fixed RTO update and dup ACKs generation.
i) there was an integer promotion problem in updating the retransmission
timeout : a signed int was being divided by an unsigned int. This was causing
the values to overflow. Thus leading to huge values for timeout which
manifested in the perception of pause in data flow.
ii) for an ack to be recognised as a duplicate ack, the advertised window
must remain same. This was not taken care of in the code so I added it.
Signed-off-by: Augustin Cavalier <waddlesplash@gmail.com>
Helps with #13769 but does not fix it completely (upload gets
farther but still stalls.)