W3C home > Mailing lists > Public > www-validator@w3.org > February 2003

Self-reference possible with validation service

From: SteveC <steve@fractalus.com>
Date: Wed, 26 Feb 2003 20:44:38 +0000
To: www-validator@w3.org
Message-ID: <20030226204438.GB3795@fractalus.com>

I looked for a while through the mailing list archive and couldn't find 
anything like this so please don't flame me :-)

It appears possible to ask the validator to check itself, then check
itself checking itself, then check itself checking itself checking
itself and so on recursively.

I tried the first 6 levels of recursion and got a roughly linearly
increasing delay of about and extra second per recursion level. This
makes it interesting as a DoS attack as you could cause multiple amounts
of load on the machine for trivial increase in network traffic.

I don't know if it is actually calling itself, but the increasing load 
time would seem to suggest it.

Please CC me on any replies!

time wget http://validator.w3.org/

real    0m0.651s
user    0m0.020s
sys     0m0.000s

time wget 
http://validator.w3.org/check?uri=http%3A%2F%2Fvalidator.w3.org%2F

real    0m1.751s
user    0m0.010s
sys     0m0.010s

 time wget
http://validator.w3.org/check?uri=http%3A%2F%2Fvalidator.w3.org%2Fcheck%3Furi%3Dhttp%253A%252F%252Fvalidator.w3.org%252F

real    0m2.428s
user    0m0.000s
sys     0m0.020s

time wget 
http://validator.w3.org/check?uri=http%3A%2F%2Fvalidator.w3.org%2Fcheck%3Furi%3Dhttp%253A%252F%252Fvalidator.w3.org%252Fcheck%253Furi%253Dhttp%25253A%25252F%25252Fvalidator.w3.org%25252Fcheck%25253Furi%25253Dhttp%2525253A%2525252F%2525252Fvalidator.w3.org%2525252F

real    0m3.433s
user    0m0.020s
sys     0m0.010s

time wget
http://validator.w3.org/check?uri=http%3A%2F%2Fvalidator.w3.org%2Fcheck%3Furi%3Dhttp%253A%252F%252Fvalidator.w3.org%252Fcheck%253Furi%253Dhttp%25253A%25252F%25252Fvalidator.w3.org%25252Fcheck%25253Furi%25253Dhttp%2525253A%2525252F%2525252Fvalidator.w3.org%2525252Fcheck%2525253Furi%2525253Dhttp%252525253A%252525252F%252525252Fvalidator.w3.org%252525252F

real    0m7.199s
user    0m0.010s
sys     0m0.020s

time wget
http://validator.w3.org/check?uri=http%3A%2F%2Fvalidator.w3.org%2Fcheck%3Furi%3Dhttp%253A%252F%252Fvalidator.w3.org%252Fcheck%253Furi%253Dhttp%25253A%25252F%25252Fvalidator.w3.org%25252Fcheck%25253Furi%25253Dhttp%2525253A%2525252F%2525252Fvalidator.w3.org%2525252Fcheck%2525253Furi%2525253Dhttp%252525253A%252525252F%252525252Fvalidator.w3.org%252525252Fcheck%252525253Furi%252525253Dhttp%25252525253A%25252525252F%25252525252Fvalidator.w3.org%25252525252F

real    0m6.063s
user    0m0.010s
sys     0m0.010s

have fun,

SteveC steve@fractalus.com http://www.fractalus.com/steve/
Received on Wednesday, 26 February 2003 15:46:56 GMT

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