ASP.Net Relative Redirects and Resource Paths

Question

We are working on the conversion of an ASP site to ASP.Net and are running into problems with redirects and resource locations. Our issues are coming from a peculiarity of our set-up. Our site can be accessed in two ways:

1. Directly by URL: http://www.mysite.com - in this case everything works fine
2. Via a proxy server with a URL like: http://www.proxy.com/mysite_proxy/proxy/

In #2 "mysite_proxy" is a mapping on proxy.com that directs the request behind the scenes to www.mysite.com, "proxy" is a virtual sub-website that just redirects the request to the root of www.mysite.com. It essntially is meant to give us a convenient way of knowing if a request is hitting the site from the proxy or not.

We are running into two problems with this setup:

1. Using Response.Redirect either with the "~" or a plain relative path (Default.aspx) generates a 302 response with a location of "/proxy/rest_of_the_path.aspx." This causes the browser to request http://www.proxy.com/proxy/rest_of_the_path.aspx which isn't anything and doesn't even hit our server so we couldn't do an after the fact re-write.
2. Using "~" based URLs in our pages for links, images, style-sheets, etc. creates the same kind of path: "/proxy/path_to_resources.css." We could probably solve some of these by using relative paths for all these resources though that would be a lot of work and it would do nothing to address similar resource links generated by the framework and 3rd party components.

Ideally I want to find a global fix that will make these problems transparent to the developers working on the site. I have a few ideas at this point:

1. Getting rid of the proxy, it is not really needed and is there for administrative and not technical reasons. Easiest to accomplish technically, the hardest to accomplish in the real world.
2. Hand the problem off to the group that runs the proxy and say it is their problem they need to fix it.
3. Use a Response filter to modify the raw html before it is sent to the client. I know this could fix my resource links, but I am not certain about the headers (need to test it out) and there would be a performance hit to having to parse every response looking for and re-writing urls.

All of these solutions have big negatives in my mind and I was hoping someone might have another idea. So any thoughts?

Aside: there are a lot of posts up already that deal with the reverse of this issue: I have a relative URL, how do I may it absolute, but I didn't come across anything that fit the bill for the other direction.

Answer 1

As a fix, I'd go with a small detection routine at Global.asax:Session_Start (since i imagine that the proxy doesn't actually starts another application instance), set a session variable with the correct path, and use it instead of '~'.

In the case a different application instance is used, then use Application_Start instead of Session_Start and a static Global variable instead of a Session variable.