Redirect and relative URL

Posted on 2004-04-07
Last Modified: 2007-12-19
Here is my problem scenario:

In my servlet I am able to successfully bypass
authentication using Base64Encoding when accessing a
password protected page.
This page can be successfully displayed as well in the
browser, if I just stream the URL content from my
servlet to the client.However if this page had
relative links in its source, these
relative links do not work at all.

To overcome this, I tried using
from within my Servlet after setting
response.setHeader("Authorization", "Basic " +
(I have also tried
response.setHeader("WWW-Authenticate", "Basic " +
Either way with redirect, now I cannot bypass
authentication, because the browser keeps asking me
for credentials.

Basically I am looking to bypass authentication and
have the password protected page work correctly even
if it has relative links. Is this possible?

Let me clarify my scenario, hopefully this will make
it more clear

a) Client requests a password protected page from my
b) servlet asks for username and password *once*.
c) Now my servlet has the user credentials in Base64
d) I use these credentials to access the protected URL
from the servlet.  I get the contents fine to display
on the client. However if this URL content has
*relative* URL links it does not work since the
relative link is relative to the URL page and not the
ServletContext, which has made the request.
e) So I tried using response.sendRedirect which only
takes a String (which would be my password protected
URL string). So I tried using
response.setHeader("Authorization", "Basic " +
(I have also tried
response.setHeader("WWW-Authenticate", "Basic " +
to set the credentials and it still does not work.
I must mention that the password protected page is not
serviced by a servlet.
In fact these pages could be are cgi scripts. I want
to ask the credentials just once and use these
credentials from then on when visiting any password
protected page *even* with relative links.

                  Any ideas?
Question by:jkini
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LVL 92

Expert Comment

ID: 10779243
i think you're going to need to parse html and modify the link before returning it to client.

Author Comment

ID: 10779314
But this is not possible since I would not even know where or which is the relative
entity (URL or gif) and which is not. Since the page could be any password protected page of the intranet whose content I have no control over or predefined knowledge of.

I am looking for some thing I can either set in the HttpServletResponse or
HttpServletRequest which I can then use to bypass authentication and achieve
what the sendRedirect would do.
LVL 92

Expert Comment

ID: 10779356
The request is being sent by the browser so you have no control.
That is why you have to modify all the links in the page to make all requests go thru your servlet so that headers can be modified.
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LVL 92

Expert Comment

ID: 10779395
you could t5ry doing a forward instead of a redirect and see how that goes.

Author Comment

ID: 10779411
Is there a way I can ask my browser my credentials s that is does not ask me? Generally when I visit
a password protected page the browser would ask me for credentials once. Then the second time
I revisit the page it does not ask me for credentials, since I guess it would
have cached it.  So there should be some way to tell the browser just that, is it not?

If there is no other way then can you give me some code  that will generically modify the relative URLs
of the page programmatically, as I am reading the content and sending to the client?


Author Comment

ID: 10779430
I tried a forward. But the requestDispatcher needs  a location within the current ServletContext. The location that I am trying to access is not within the current ServletContext. It is just a cgi .pl script
that is not even serviced by a Servlet. So forward is not getting me anywhere :(
LVL 92

Accepted Solution

objects earned 100 total points
ID: 10779449
> So there should be some way to tell the browser just that, is it not?

The browser is storing the authentication details, but it is authenticating with your servlet and not the actaul server.
That is why you need to change all links to instead go thru your servlet.

Author Comment

ID: 10795071
I appreciate the comments made above, however the above proposal does not seem to be a feasible solution to my problem, since I still see no way of how I can determine which are the link I need to change to bypass authentication and which are the links which are simply relative resources. Recreating the entire HTML content, just does not seem like an appropriate

If anyone can send me some **code**  that is a feasible solution that I can **use**
then I can award the points to that person. If not I will just have to request to delete my question.
LVL 92

Expert Comment

ID: 10795088
There is no other solution that I am aware of for the reasons I have mentioned above.
Just because you do not like the required solution does not make it invalid.

Author Comment

ID: 10795277
Probably. But if the solution is not feasible for the reasons I mentioned it is not worth
the 100 points that I assigned to the question, since I have received no code. I expect a workable
code if this happens to be a solution to assign points. So far I have requested code 3 times
and none has been provided.

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