Re: open relay testing

From: Wietse Venema (no email)
Date: Mon Mar 03 2003 - 09:06:33 EST


Jos? Luis Tall?n:
>
> >There is an unfinished dict_tcp module in the Postfix source code.
>
> Cool
>
> >It compiles and works. But that does not matter, because the design
> >needs to be revised.
>
> Any guidelines / requirements / constraints so that we can start thinking ??

It's the usual:

- The Postfix client side must be suitable for a hostile environment,
so it must recover when the server

    - disconnects unexpectedly (like while the client sends a request),

    - sends incorrectly formatted responses,

    - sends overly long responses,

    - does not respond within some time limit,

    - etcetera

- Queries and replies must be easy to parse and generate with
scripting languages like PERL.

- The encoding of queries and replies must be unambiguous: don't
use newlines as terminators if there is any chance that such
characters will be embedded in the data.

- I want to use a format where queries and replies are sequences
of named attributes. This way the protocol is extensible and can
be also be used for future multi-parameter queries and whatnot.

I was thinking of using an attr_print64/scan64() like format. This
uses base64 as the encoding. However, the present attr_print64/scan64()
implementation still needs to be hardened before it can be used in a
hostile environment. See the above requirements list.

Oh, and Liviu Daia would like to have a version that can talk UDP.

> As always, thanks for a wonderful program.

You're welcome.

        Wietse








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