[plt-scheme] Cookies to web servlet getting lost when __utmz cookie present

Thanks, Jay.

That's kind of annoying though -- I mean I can't do anything about the
cookies that Google requests the browser to set when other pages on
the domain are visited. And I tried different browsers -- the same
problem. Why would Google Analytics be setting invalid cookies? (A
search doesn't seem to turn up any relevant hits, or anyone else every
experience this issue.)

So basically, I need to parse the headers for cookies in my own program?

--- nadeem


On Fri, Apr 30, 2010 at 12:26 AM, Jay McCarthy <jay.mccarthy at gmail.com> wrote:
> Hi Nadeem,
>
> The problem is that this:
>
> "teaching-order=course;
> __utmz=165257760.1272597702.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none)\r\n"
>
> is not a valid cookie. In particular, the characters to the right of
> the second "=":
>
> "165257760.1272597702.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none)\r\n"
>
> should be a VALUE, which is a value, which is either a token or a quoted-string.
>
> It is not a token because it contains "(", ")", and "=".
>
> It is not a quoted-string because it is not wrapped in "".
>
> The Web Server does not throw an exception when it is asked to parse
> an invalid cookie string, instead it returns the empty list of
> cookies. You can look at the request's headers directly to do
> something to this header, but since it is not a cookie, the Web
> Server's cookie parsing cannot do anything with it.
>
> For Reference:
>
> http://tools.ietf.org/html/rfc2965 [for VALUE and value]
> http://tools.ietf.org/html/rfc2616 [for token and quoted-string]
>
> Jay
>
> On Thu, Apr 29, 2010 at 10:05 PM, Nadeem Abdul Hamid <nadeem at acm.org> wrote:
>> Hello all,
>>
>> I've been experimenting with a simple servlet to drive my website, but am having a strange problem with cookies not getting through when a Google Analytics cookie (__utmz) is present in the browser's request to the servlet. I've included a step-by-step trace below, but briefly, here's the problem: Starting from an empty browser cache of cookies, I request a page from my servlet that sets a cookie; when I then request a page again, I see that the cookie is sent by the browser and received by the servlet. However, then I visit another web page on the same domain as my servlet, which sets a __utmz (apparently a Google Analytics cookie). After this cookie is set, when I request pages from my servlet, I see that the browser is sending all the cookies, but none are getting through to the servlet! If I clear the __utmz cookie from the browser, and then request pages from the servlet, the servlet receives the cookie again.
>>
>> So, I haven't peeked into the webserver code (no time yet), but the question is: is there some reason that the __utmz cookie (and not any other __utma, __utmc, cookies) seems to cause interference with all other cookies getting through to it?
>>
>> Below are the steps that I take to replicate this problem, as well as snippets from my code. I added some terminal output to the servlet dispatch function that is passed to serve/servlet so that it displays the cookies it receives and the URL being requested before doing anything else.
>>
>> I appreciate any help/insight. Thanks,
>>
>> --- nadeem
>>
>>
>> **************************************************************
>> (Step 1)
>> Browser request (sniffed using Wireshark):
>>   GET /~nhamid/teaching/ HTTP/1.1\r\n
>>   (no cookies sent)
>>
>> Servlet output:
>>   ()/~nhamid/teaching/
>>
>>
>> (Step 2)
>>   request page that sets a cookie (and redirects to /~nhamid/teaching/course…)
>>
>>
>> (Step 3)
>> Browser request:
>>   GET /~nhamid/teaching/course HTTP/1.1\r\n
>>   Cookie: teaching-order=course\r\n
>>
>> Servlet output:
>>   ((teaching-order course #f #f))/~nhamid/teaching/course
>> (See the cookie is received.)
>>
>>
>> (Step 4) visit another page (www.berry.edu) -- sets __utmz (google analytics cookie) and a bunch of others, which I cleared out, except for the __utmz one.
>>
>>
>> (Step 5)
>> Browser request:
>>   GET /~nhamid/teaching/ HTTP/1.1\r\n
>>   Cookie: teaching-order=course; __utmz=165257760.1272597702.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none)\r\n
>>
>> Servlet output:
>>   ()/~nhamid/teaching/
>> (Note: no cookies received at all!)
>>
>>
>> (Step 6) delete the __utmz cookie from the browser. This is the *only* thing I change.
>>
>>
>> (Step 7)
>> Browser request:
>>   GET /~nhamid/teaching/ HTTP/1.1\r\n
>>   Cookie: teaching-order=course\r\n
>>
>> Servlet output:
>>   ((teaching-order course #f #f))/~nhamid/teaching/
>> (Cookie is received again!)
>>
>> **************************************************************
>>
>> Scheme code:
>>
>> (serve/servlet my-dispatch
>>               #:listen-ip #f
>>               #:launch-browser? #f
>>               #:servlet-path "/nhamid/index.ss"
>>               #:servlet-regexp #rx""
>>               #:extra-files-paths (list htdocs)
>>               #:stateless? false)
>>
>> (define-values (web-dispatch web-url)
>>  (dispatch-rules
>>   [("~nhamid" "index.ss") render-home]
>>   [("~nhamid") render-home]
>>   [("~nhamid" "") render-home]
>>   [("~nhamid" "editlinks") render-editlinks]
>>   [("~nhamid" "teaching" "") render-teaching]
>>   [("~nhamid" "teaching" "semester") render-teaching-by-semester]
>>   [("~nhamid" "teaching" "course") render-teaching-by-course]
>> ))
>>
>> (define (display-cookies req)
>>  (let ([cookies (request-cookies req)])
>>    (display
>>    (map (lambda (c) (list (client-cookie-name  c)
>>                           (client-cookie-value c)
>>                           (client-cookie-domain c)
>>                           (client-cookie-path c)))
>>         cookies))))
>>
>> ;; my-dispatch : request -> response
>> (define (my-dispatch req)
>>  (display-cookies req)
>>  (display (string-append (url->string (request-uri req)) "\n"))
>>  (web-dispatch req))
>>
>>
>> _________________________________________________
>>  For list-related administrative tasks:
>>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme
>>
>
>
>
> --
> Jay McCarthy <jay at cs.byu.edu>
> Assistant Professor / Brigham Young University
> http://teammccarthy.org/jay
>
> "The glory of God is Intelligence" - D&C 93
>



-- 
Nadeem Abdul Hamid
Assistant Professor, Computer Science
Berry College
PO Box 5014
2277 Martha Berry Hwy NW
Mount Berry, GA 30149-5014
(706) 368-5632
http://cs.berry.edu/~nhamid/