Return full HTTP Response in ASP.Net WebAPI Controller

Question

I'm trying to return a full HTTP-Response to the browser within an ASP.NET WebAPI Controller.

The scenario is the following: I make a remote call to another webserver and get a full HTTP-Message including the HTTP Headers and content. I just want do deliver this message "as is" to the browser.

Does anyone know how to do this?

Answer 1

Create your own IHttpHandler and configure a route for it. You have to copy all response headers from your own response to the response object of ASP.NET.

Here is a sample implementation for another scenario:

public class CorsProxyHttpHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        var url = context.Request.Headers["X-CorsProxy-Url"];
        if (url == null)
        {
            context.Response.StatusCode = 501;
            context.Response.StatusDescription =
                "X-CorsProxy-Url was not specified. The corsproxy should only be invoked from the proxy JavaScript.";
            context.Response.End();
            return;
        }

        try
        {
            var request = WebRequest.CreateHttp(url);
            context.Request.CopyHeadersTo(request);
            request.Method = context.Request.HttpMethod;
            request.ContentType = context.Request.ContentType;
            request.UserAgent = context.Request.UserAgent;

            if (context.Request.AcceptTypes != null)
            request.Accept = string.Join(";", context.Request.AcceptTypes);

            if (context.Request.UrlReferrer != null)
                request.Referer = context.Request.UrlReferrer.ToString();

            if (!context.Request.HttpMethod.Equals("GET", StringComparison.OrdinalIgnoreCase))
                context.Request.InputStream.CopyTo(request.GetRequestStream());

            var response = (HttpWebResponse)request.GetResponse();
            response.CopyHeadersTo(context.Response);
            context.Response.ContentType = response.ContentType;
            context.Response.StatusCode =(int) response.StatusCode;
            context.Response.StatusDescription = response.StatusDescription;

            var stream = response.GetResponseStream();
            if (stream != null && response.ContentLength > 0)
            {
                stream.CopyTo(context.Response.OutputStream);
                stream.Flush();
            }
        }
        catch (WebException exception)
        {
            context.Response.AddHeader("X-CorsProxy-InternalFailure",  "false");

            var response = exception.Response as HttpWebResponse;
            if (response != null)
            {
                context.Response.StatusCode = (int)response.StatusCode;
                context.Response.StatusDescription = response.StatusDescription;
                response.CopyHeadersTo(context.Response);
                var stream = response.GetResponseStream();
                if (stream != null)
                    stream.CopyTo(context.Response.OutputStream);

                return;
            }

            context.Response.StatusCode = 501;
            context.Response.StatusDescription = exception.Status.ToString();
            var msg = Encoding.ASCII.GetBytes(exception.Message);
            context.Response.OutputStream.Write(msg, 0, msg.Length);
            context.Response.Close();

        }
        catch (Exception exception)
        {
            context.Response.StatusCode = 501;
            context.Response.StatusDescription = "Failed to call proxied url.";
            context.Response.AddHeader("X-CorsProxy-InternalFailure", "true");
            var msg = Encoding.ASCII.GetBytes(exception.Message);
            context.Response.OutputStream.Write(msg, 0, msg.Length);
            context.Response.Close();

        }
    }

    public bool IsReusable { get { return true; }}
}

(from my article: http://blog.gauffin.org/2014/04/how-to-use-cors-requests-in-internet-explorer-9-and-below/)