UDNS issue

[Abhijit Pandey]

Hi Michael,


When I use Dig with +bufsize=4096 , the Query packet sent out is
identical to sent out by dnsget, except

With dnsget
1) Don't Fagment bit is set.
2) Identification 16 bits is 0

Looks like this particular difference in Query brings different responses back.

Abhijit

On Tue, Feb 3, 2009 at 12:05 AM, Michael Tokarev <mjt+udns at corpit.ru> wrote:
> Abhijit Pandey wrote:
>> Hi Michael,
>>
>> Setting $ RES_OPTIONS="udpbuf=512" ./dnsget ...   did solved the problem.
>
> Well, as I predicted.  But how about my question - what resolver
> do you have, which software/brand/version?
>
>> I was using Rich formatting of Gmail, which probably your E-mail
>> client didn't understand.
>
> My client understands html, but your mail client decided to add
> html link tags around every word with at least one dot in it,
> "thinking" it is an URL which it is not.  Like all domain names
> we were querying.
>
>> I am investigating using UDNS for asynchronous queries(A and TXT
>> records), in a production environment for heavy loads.
>> dnsget seems to give a fairly good idea, of how to use the API's
>
> Well, the API and the whole thing is simple enough to be useful,
> I think.  It was one of the library's main goals: easy to use
> interface.
>
>> I see UDNS is being used in various distributions(Gentoo/Ubuntu/Fedora etc).
>> Hopefully I wouldn't any bugs to fix.
>
> Let's hope so.. ;)  The only problem I know of is the one you
> faced already: sometimes the library is unable to work because
> some resolver nearby does not understand or does not properly
> implement EDNS0 extensions (which are turned off using the above
> workaround).  Unfortunately, in all such cases I know (about 3
> or 4 reports so far) no one replied to me telling which software
> it is that's broken.  You too ignored my question of that sort...
> It'd be VERY interesting to know which software misbehaves with
> EDNS0 extensions in use.  Thanks!
>
> /mjt
>