Re: [lwip-devel] TCP implementation voilates RFC 793

[Rüdiger Asche]

I don't necessarily see a violation of RFC behavior. In the RFC793
section Elena quotes, this statement is included:

"If the RCV.WND is zero, no segments will be acceptable, but special
allowance should be made to accept valid ACKs, URGs and RSTs."

Wouldn't this allow for the behavior she sees?

Apologies if I should have overlooked something obvious...


2014-02-03, Simon Goldschmidt <address@hidden>:
>  "Elena Gurevich" wrote:
>
>> As I understand that all control information ( SYN, FIN, ACK, ack_no,
>> window ) filed should be ignored and not processed in case of unacceptable
>> segment arrival.
>> According tcp_receive() function from first of all it takes care of ack_no
>> and window field for segment with ACK ? uses actual ack_no and windows
>> values to update tcb
>> and takes into account segment seq_no only at data processing step.
>>
>> This looks like strong violation of RFC defined behavior.
>
> From memory, I think you might be right, but I'll have to double check
> that.
>
> Could you please file a bug report for this? It might get forgotten
> otherwise, as developers tend to not have the time to monitor this list...
>
>>  I am a new member of lwIP and intended to use the TCP implementation as a
>> "golden" reference, but very confused now.
>
> That's flattering, but still lwIP is not bug-free :-) Thanks for your
> input.
>
>
> Simon
>