Sending image with HttpListener only working for some images

Question

I'm trying create a small http proxy service. This is not working so well. It is able to serve HTML okayish, however it chokes up on images. That is, some images.

Sending in a url through my proxy yields 19.4 kb in the response (according to firebug) Visiting that url directly also yields 19.4 kb in the response, again according to firebug. The difference is, it doesn't show up when I put it through my proxy, but it does when I browse directly.

A completely different url works just fine. Does anyone have any idea?

private void DoProxy()
{
    var http = listener.GetContext();
    string url = http.Request.QueryString["url"];
    WebRequest request = HttpWebRequest.Create(url);
    WebResponse response = request.GetResponse();
    http.Response.ContentType = response.ContentType;

    byte[] content;
    using (Stream responseStream = response.GetResponseStream())
        content = ReadAll(responseStream);
    http.Response.ContentLength64 = content.Length;
    http.Response.OutputStream.Write(content, 0, content.Length);
    http.Response.Close();
}

private byte[] ReadAll(Stream stream)
{
    IList<byte> array = new List<byte>();
    int b;
    while ((b = stream.ReadByte()) != -1)
        array.Add(Convert.ToByte(b));
    return array.ToArray();
}

Answer 1

I would try and flush/close the OutputStream before you close the response.

Also as a second suggestion have a look at the HTTP traffic from the original site and then through your proxy site using an HTTP debugger like Fiddler - there must be a difference when using your proxy.

Also to make the ReadAll method more effective, in general I would avoid to load the full content into memory, because this will blow up on huge files - just stream them directly from the input stream to the output stream. If you still want to use byte arrays consider the following (untested but should work):

private byte[] ReadAll(Stream stream)
{
    byte[] buffer = new byte[8192];
    int bytesRead = 1;
    List<byte> arrayList = new List<byte>();

    while (bytesRead > 0)
    {
        bytesRead = stream.Read(buffer, 0, buffer.Length);
        arrayList.AddRange(new ArraySegment<byte>(buffer, 0, bytesRead).Array);
    }
    return arrayList.ToArray();
}

Answer 2

You can try to replace

http.Response.Close();

with

http.Response.Flush();
http.Response.End();

Answer 3

A problem could be that you don't specify the MIME type of the response. Browsersthese days are very forgiving, but maybe there is a circumstance where the browser doesn't know how to handle whatever you are sticking through its throat.

I have written the most smallish file-based http server, presented here, which as far as I can remember can serve images without much problem.