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  • From: ark AT eltex.ru
  • To: freetds AT franklin.oit.unc.edu
  • Subject: Re: OOB data
  • Date: Fri, 23 Apr 1999 10:44:24 +0400


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nuqneH,

Thanks! That made things much more clear for me.. Does anybody know
the format of cancel/attention requests and server ack packet?
Dump those packets for me at least?

"Scott C. Gray" <gray AT voicenet.com> said :

> > Does anybody know how OOB data are used in TDS protocol?
> > I am trying to write a proxy for TDS. I've noticed that MS SQL client
> > sends something like cleanup request in OOB (it does happen when i close
> > a request window or somth like that in client program). Real PITA for now,
> > as far as i seen FreeTDS library does not handle OOB data so i could not
> > find any reference what to do (i cannot transmit it "as is" because i
> > have a TCP crypto tunnel that does not handle OOB so i need a way to
> > translate it to whatever else). Any hints?
>
> I can't speak much for FreeTDS libraries, but I can talk a little
> bit about how OOB packets are utilized in Sybase TDS 4.6 and 5.0.
>
> In TDS 4.6, a cancel--or attention--request (usually made via a
> call to dbcancel() in db-library) generated an OOB packet which
> caused a SIGURG signal to be raised in the server on the other
> end of the pipe. Upon sending the OOB packet, the client library
> would then read and discard packets from the network until it
> received an acknowledgement of the packet from the server. Once
> it receivees this acknolwedgement it knows that the communications
> state of the network has been reset, packets are no longer waiting
> and it may now issue new queries.

[dd]

_ _ _ _ _ _ _
{::} {::} {::} CU in Hell _| o |_ | | _|| | / _||_| |_ |_ |_
(##) (##) (##) /Arkan#iD |_ o _||_| _||_| / _| | o |_||_||_|
[||] [||] [||] Do i believe in Bible? Hell,man,i've seen one!

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