Is HttpWebResponse Auto Decompression supported in Mono?

Question

I have the following code:

var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/test.xml.gz");
request.UserAgent = "TEST";
request.Accept = "*/*";
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;

var response = (HttpWebResponse)request.GetResponse();
var stream = response.GetResponseStream();
var buffer = new byte[4096];
int read;
if (File.Exists("test.txt"))
    File.Delete("test.txt");
var file = new FileStream("test.txt", FileMode.CreateNew);

while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
    file.Write(buffer, 0, read);

file.Close();
stream.Dispose();

When I run it on Windows, I get the file decompressed at 8M. When I run it on Mono test.txt is 521K of compressed data.

I am using Mono 3.2.6 compiled from tarball. (Edit: on Debian 7.3 installed under /usr/local/lib)

Am I doing something wrong, or is this feature not currently supported in Mono?

Answer 1

I appears that auto-decompression is supported, but the implementation solely depends on the headers sent by the server. In my particular case I'm trying to crawl a crappy website that is not sending the correct content-encoding even though the response is compressed. My guess would be that the MS impl in typical MS fashion attempts to go beyond the headers check and perhaps adds the GZ magic first two bytes, etc.

In any case, for anyone who might find themselves in this spot in the future, here's my solution:

var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/test.xml.gz");
request.Accept = "*/*";
request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;

var response = (HttpWebResponse)request.GetResponse();

var mem = new MemoryStream() as Stream;
using (var stream = response.GetResponseStream())
    stream.CopyTo(mem);

var bytes = (mem as MemoryStream).GetBuffer();
if (bytes[0] == '\x1F' && bytes[1] == '\x8B')
{
    mem.Position = 0;
    mem = new GZipStream(mem, CompressionMode.Decompress);
    var uncompressed = new MemoryStream(bytes.Length * 20);
    mem.CopyTo(uncompressed);
    mem.Dispose();
    mem = uncompressed;
}

if (File.Exists("lala.txt"))
    File.Delete("lala.txt");
var file = new FileStream("lala.txt", FileMode.CreateNew);
mem.Position = 0;
mem.CopyTo(file);
file.Close();

(NOTE: That I'm not disposing of everything correctly here, this is just example code.)