Re: BIG WARNING - validation controls appear to be ignored.

From: Lau Lei Cheong (leu_lc_at_yehoo.com.hk)
Date: 02/25/05

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    Date: Fri, 25 Feb 2005 09:34:27 +0800

    Just like any client-side checking using vbscript/javascript, they can
    always be overrided.

    So never just do client-side checking of data, do server-side checking on
    the received data as well.

    This may seem redundant, but client-side check enables quicker response and
    fewer postbacks, while server-side check makes your data safer.

    "Andy Fish" <ajfish@blueyonder.co.uk> ¦b¶l¥ó
    news:OyahI6oGFHA.3472@TK2MSFTNGP09.phx.gbl ¤¤¼¶¼g...
    > Hi,
    >
    > Although I have got to the bottom of this problem, it gave me quite a
    shock
    > to discover how easy it is to write a very unsafe application with .Net
    > validators.
    >
    > The scenario was this: we wrote and tested an application using
    validators,
    > but when we deployed the app onto a different server, it accepted and
    > processed invalid input from the user.
    >
    > Turns out that in testing the validators were running client-side. When a
    > client-side validator blocks the input there is no postback and hence
    > nothing happens on the server. However, if client-side validation is
    > disabled for any reason, all control events fire on the server even if the
    > page is invalid. If, like me, you were expecting the page processing to
    > finish in the event of a validation faliure and not fire button clicks
    etc,
    > you are sadly mistaken. If you use validators, you must check manually
    > Page.IsValid in every "click" event.
    >
    > I realise this is probably in the documentation (section 34.4b(ii)
    > subsection 2(i) sub-paragraph 23a.3.64) and many of you gurus will think
    > this is obvious, but I'm sure that there must be hundreds of apps out
    there
    > that are unwittingly relying on client-side validation.
    >
    > The moral is this: ALWAYS TEST THE APPLICATION WITH CLIENT SIDE VALIDATION
    > DISABLED. the default configuration could lull you into a false sense of
    > security and could lead to shipping an unsafe application.
    >
    > Andy
    >
    >

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