Re: [vpp-dev] Is the tcp connection timestamp updated too early

[liuyacan]

Hi Florin,

   when we use packetdrill to inject a bad packet with high tsval which ACK sequence is above SNDNXT,  we found that subsequent normal packet are not accepted.

BR,

yacan

On 4/1/2021 11:29，Florin Coras<fcoras.li...@gmail.com> wrote：

Hi Yacan, 

We only update tc->tsval_recent if the segment is fine and tc->tsval_recent is less than rcv_opts.tsval, i.e., the new tsval moves forward. Even if the ack is dropped, we only use tsval_recent in paws check. On the other hand rcv_opts.tsecr is not used unless the ack is valid. 

Did you hit any issue in particular?  

Regards,

Florin  

On Mar 31, 2021, at 7:00 PM, liuyacan <liuya...@corp.netease.com> wrote:

Hi,

 

    For ESTABLISHED tcp connection, its timestamp is updated in tcp_segment_validate()->tcp_options_parse(), 

    but if after this , the ACK field check failed,  then the packet  would be dropped. 

    Do we need to restore the timestamp of the connection ?

Thanks,

Yacan

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