Re: spec review: ping attribute

Henri Sivonen wrote:
> On Oct 27, 2007, at 19:12, Julian Reschke wrote:
> 
>> Geoffrey Sneddon wrote:
>>> Having read this entire thread, I don't see why anything is actually 
>>> wrong. In this context the difference between GET and POST is 
>>> negligible — both can technically be used to do what is desired, 
>>> though using GET would be breaking RFC 2616 (or rather, breaking a 
>>> SHOULD NOT). If we
>>
>> No, sorry, that's incorrect.
>>
>> If you want to do something silently (without the user's consent), you 
>> simply have to use a safe method.
> 
> So would you ban XHR POST and script-initiated form submissions?

I would want the XHR spec to clarify that it's not OK to initiate unsafe 
methods without the user's consent. I would also deprecate 
script-initiated form submissions from something like onload().

> The ping attribute does have the same security risks that cross-domain 
> XHR POST with empty entity body would have if the access-control 
> Method-Check weren't there. That is, if a POST handler has been 
> programmed to trigger stuff on mere POST without a body, a malicious 
> ping attribute could be used to trigger that action.
> 
>> And if you consider the desired effect non-safe (which I don't), then 
>> the consequence is that you just can't do it.
> 
> It is about idempotent vs. non-idempotent and side effects.
> 
> If you are counting ad impressions, clearly you don't want to
>  a) count Google Web Accelerator (or similar) prefetches
>  b) leave impressions uncounted due to an intermediate cache satisfying 
> the request.

Yes. But the same problem can (and is) already used without "ping", and 
even if you use "ping", you still could do it with a safe method 
(HEAD/Cache-Control:no-cache).

Best regards, Julian