[lwip-devel] receiving of an unacceptable ack does not elicit an empty ack

[narke]

Hi,

When I was testing the code (1.4.0), I found when lwIP received an
unacceptable acknowledge (ackno == snd_nxt + 1), it output nothing.
But, according to RFC 793, page 36:

    3.  If the connection is in a synchronized state (ESTABLISHED,
    FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, CLOSING, LAST-ACK, TIME-WAIT),
    any unacceptable segment (out of window sequence number or
    unacceptible acknowledgment number) must elicit only an empty
    acknowledgment segment containing the current send-sequence number
    and an acknowledgment indicating the next sequence number expected
    to be received, and the connection remains in the same state.

an empty acknowledgment segment should be sent.


Can someone confirm this and is it a bug?

Thanks in advance.

-- 
Life is the only flaw in an otherwise perfect nonexistence
    -- Schopenhauer

narke
public key at http://subkeys.pgp.net:11371 (address@hidden)