asp.net webservice handling gzip compressed request

Question

I have an asp.net .asmx webservice written to handle requests from a third party tool. The third party tool makes an http POST request to the webservice to get user information. I'm using IIS7 Running Fiddler with "Remove All Encodings" checked, I can see the webservice call and and everything functions properly. If I uncheck "Remove All Encodings", the webservice call fails with a 400 Bad Request. The difference I see is that the header "Content-Encoding: gzip" is being removed by Fiddler and the content is being decompressed. So, when the Content-Encoding header is removed and the content is decompressed, my webservice functions perfectly. When the header is present and the content is compressed, the webservice fails. How can I either: - Configure my webservice to tell the client that it won't accept compressed requests (and hope that the third party tool respects that) - Decompress the content early in the asp.net handling - Modify my webservice to work with compressed data Update:…

Accepted Answer

I've found a partial answer here.

```
class DecompressStream : Stream
{
    ...

public override int Read(byte[] buffer, int offset, int count)
    {
        GZipStream test = new GZipStream(_sink, CompressionMode.Decompress);

int c = test.Read(buffer, offset, count);

return c;
    }

...
}
```

I can then specify the filter on the request object like this:

```
void Application_BeginRequest(object sender, EventArgs e)
    {
        string contentEncoding = Request.Headers["Content-Encoding"];
        Stream prevCompressedStream = Request.Filter;

if(contentEncoding == null || contentEncoding.Length == 0)
            return;

contentEncoding = contentEncoding.ToLower();

if(contentEncoding.Contains("gzip"))
        {
            Request.Filter = new DecompressStream(Request.Filter);
        }
    }
```

I say partial answer because even though I can now process the incoming request, the response is getting a "Content-Encoding: gzip" header even though the response is not encoded. I can verify in Fiddler that the content is not encoded.

If I do encode the response, the client for the webservice fails. It seems that even though it is sending "Accept-Encoding: gzip", it does not in fact accept gzip compressed response. I can verify in Fiddler that the response is compressed and Fiddler will decompress it successfully.

So, now I'm stuck trying to get a stray "Content-Encoding: gzip" header removed from the response. I've removed all references I can find to compression from the application, the web.config, and IIS.

asp.net webservice handling gzip compressed request

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