How to get WebResource.axd querystring in correct case?

Question

I am getting the css files for minifying and compressing from QueryString["path"] everything works correctly for my own css files like main.css. But when I try to acess the webresource files I receive a 500 error. The parameter which comes after the webresource.axd is case sensitive and I receive it from QueryString["path"] lowercase.

This is what I get from QueryString["path"] :

http://localhost/test/webresource.axd?d=-phgrn6r6zgehvbi697-bxvkl_gidnplxpdeukz5kncgr9hvnfvttpgykwyw05cda-nymtz9od_bbww3ynzxha2&t=633789305460522066

The above link generate error : CryptographicException: Padding is invalid and cannot be removed.

This is what the correct link look like :

http://localhost/test/WebResource.axd?d=-pHGRn6r6ZGehvBI697-BxVKl_GIdNPlxPdEUKZ5KNcGR9hvnfVtTpgyKwYw05cDa-NymTz9OD_bBwW3ynZXhA2&t=633789305460522066

The only difference is in the case. CryptographicException seem to be common but even setting machineKey didn't fixed the problem. Any hint on how could I get the the webresource.axd in the original case?

EDIT

Code was requested :

public void ProcessRequest(HttpContext context) {
    Control c = new Control();
    string root = context.Request.Url.GetLeftPart(UriPartial.Authority);
    string path = context.Request.QueryString["path"];
    string content = string.Empty;

    if (!string.IsNullOrEmpty(path)) {
        if (context.Cache[path] == null) {
            List<string> dependencies = new List<string>();
            string[] styles = path.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
            foreach (string style in styles) {
                content += RetrieveStyle(root + c.ResolveUrl(style)) + Environment.NewLine;
                dependencies.Add(context.Server.MapPath(style));
            }
            content = StripWhitespace(content);
            context.Cache.Insert(path, content, new CacheDependency(dependencies.ToArray()), Cache.NoAbsoluteExpiration, new TimeSpan(DAYS_IN_CACHE, 0, 0, 0));
        }
    }
}

It crashes in RetreiveStyle when I call :

using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())

Answer 1

The culprit looks like the code that is generating the “path” querystring csv or some hardware or filter between that source and your handler.

If the source of handler request is a browser what does the handler url look like through view source or firebug? Is it lowercase already?

Working forward from that, do you have any modules etc registered in you IIS pipeline?

Answer 2

I do not have an answer but we have experienced a similar problem and I have a few things to add, which could help identifying the issue. So, here it goes:

We have an iHTTPHandler (lets call it Login.ashx) that accepts a GET request, which contains a token in base64 format. The token is then decrypted using Rijndael algorithm.

This process is working most of the time, however, in the last month we had several requests that failed due to System.Security.Cryptography.CryptographicException: Padding is invalid and cannot be removed. error. This error is raised in our case when a token (base64 string) is in lowercase and cannot be decrypted.

After going through logs and activity records I can see that a particular user would attempt to come to our side via Login.ashx and the request would fail due to the error in question. The whole querystring of the request (there is more than just token) including names and values is in lowercase. Then the same user would attempt a login a few minutes later and is able to get in because the querystring was not transformed to lower case.

So, I have a feeling that the issue could be browser related. I am not sure if proxy could affect this.

Additional info: There is no browser information captured in the server variables. ALL_HTTP and ALL_RAW variables have almost no data:

• ALL_HTTP HTTP_CACHE_CONTROL: no-cache HTTP_HOST:our server name
• ALL_RAW Cache-Control: no-cache Host: our server name

There is also no HTTP_REFFERER.

I have tried to replicate this issue with different browsers (Safari3, Chrome1, Opera9.2, IE6,7,8, Firefox3) with no luck.

We have a web farm with 10 servers configured identically (at least I hope they are)

I will add more info if I get any progress.