问题
Original Question:
We have an odd error with WebResource.axd url generation. (It does not seem to be related to the fairly common "WebRsource.axd Padding is invalid and cannot be removed" issue).
We have an ASP.NET web page that, when created, adds a script reference to WebResource.axd.
In this case, we're seeing that the WebResource.axd link occasionally turns into garbage past a certain point, replaced by what looks like javascript. Worse yet, the url generation failure seems to be inconsistant.
In our case, the link should (and usually does look like):
/WebResource.axd?d=D-wd7RbHCvSp_p0mHAmE4g2&t=633464867255568315
All well and good. However, we are getting errors logged from users...and the url they're trying to access looks like (in one case):
/WebResource.axd?d=D-wd7RbHCvS/../../images/icons/Ico_resize.gif')}}function%20ShowFilter_Manufacturer(){var%20div.......
[the remaining encoded javascript from that link has been removed as irrelevant]
Stranger yet, we got a few of these in rapid succession from the same user, who was apparently trying to reload the page...each url slightly different.
/WebResource.axd?d=D-wd7RbHCvS<garbage>
/WebResource.axd?d=D-wd7RbHCvSp<garbage>
/WebResource.axd?d=D-wd7RbHCvSp_<garbage>
In some cases the garbage is encoded JavaScript, I've seen portions of a url...completely empty parameter strings...I don't see an obvious pattern.
As an aside, should it be relevant, it should be noted that I don't believe that this WebResource is anything other than a stock WebResource that is automatically included by .NET when certain features are included on a page...in this case, a field validator. Looking at the contents of the actual WebResource.axd reveals very standard looking set of Javascript functions that seem designed to handle generic .NET events. Not anything we've created.
Has anyone seen anything like this? (or better, has anyone understood why this was happening, and come up with a way to eliminate it?)
EDIT 0: Some additional information:
Item 1: In response to one answer, we made sure that our scripts are encased with CDATA tags, since our doctype is xhtml transitional:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
Unfortunately, though we had high hopes, it does not seem to have solved the problem. We've noticed this more often with IE 8 as a browser, which would lend some credence to the idea that this is browser related...perhaps the way the browser is parsing the stream...but why we would get subtly different responses on subsequent attempts baffles me.
Item 2: It turns out that the omitted sections seem to be blocks of fairly regular size. Someone reported that he was seeing 1k or 4k blocks missing, and I (so far...I've only looked at two cases thus far) would agree (mine were both missing 4096 bytes of data).
回答1:
according to this post:
http://bytes.com/topic/asp-net/answers/861764-invalid-viewstate-system-string-decryptstringwithiv
It seems that the problem is caused by the way browsers render pages differently when the doctype is not specified.
Here is another interesting post i found on this subject, still not the solution though:
http://blog.aproductofsociety.org/?p=11
on the above page it has "Response.Cache.SetNoStore()" as a possible solution in the comments, i'll try this next to see if it helps.
回答2:
Microsoft has responded to this issue:
Note is a bug in Internet Explorer 8. The Internet Explorer team has been investigating this issue.
-=Impact=- Thus far, we believe the problem has no impact on the end-user's experience with the web application; the only negative effect is the spurious/malformed requests sent by the JavaScript speculative-download engine. When the script is actually needed by the parser, it will properly be downloaded and used at that time.
-=Circumstances=- The spurious-request appears to occur only in certain timing situations, only when a META HTTP-EQUIV tag containing a Content-Type with a CHARSET directive appears in the document, and only when a JavaScript SRC URL spans the 4096th byte of the HTTP response body.
-=Workaround=- Hence, we currently believe this issue can be mitigated by declaring the CHARSET of the page using the HTTP Content-Type header rather than specifying it within the page.
So, rather than putting
[META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8"]
In your head tag, instead, send the following HTTP response header:
Content-Type: text/html; charset=utf-8
Note that specification of the charset in the HTTP header results in improved performance in all browsers, because the browser's parsers need not restart parsing from the beginning upon encountering the character set declaration. Furthermore, using the HTTP header helps mitigate certain XSS attack vectors.
NOTE: There have been reports that this problem still happens when the META HTTP-EQUIV is not on the page. We will update this comment when we have more investigation. Posted by Microsoft on 6/30/2009 at 12:25 PM
回答3:
I am from the ASP.NET team -- we are looking for a customer willing to work with us on researching this issue. If anyone is able to reliably reproduce the problem by requesting their own pages and checking the logs, and is willing to work with our support group, please respond or send me a direct message. Thanks!
回答4:
What version of .NET are you compiling against? What happens if you change your build to build for an older or newer version? (not sure if this would do anything but it's worth a try)
If it's still happening, I think you should post a bug about it on Microsoft Connect. They should come back to you pretty quickly.
回答5:
Have you got any HttpHandlers or Modules that are registered in the web config that modify the rendered HTML before it's sent to the user?
These can often be:
- Minifiying JS and CSS
- Ensure HTML is valid
Might be worth a look.
回答6:
This is an old post... but I've came across through a google search and reminded me of this...
http://www.troyhunt.com/2010/09/fear-uncertainty-and-and-padding-oracle.html
Could it have been related?
回答7:
This was eventually fixed by Microsoft:
http://blogs.msdn.com/b/ieinternals/archive/2010/04/01/ie8-lookahead-downloader-fixed.aspx
来源：https://stackoverflow.com/questions/461605/invalid-webresource-axd-parameters-being-generated