Using Web API as a proxy for downloading files

webApi-File-Proxy-Controller.cs

public Task<HttpResponseMessage> Get()
{
  var resourceUrl = "..............";
	var range = ExtractRange(this.Request.Headers);

	var request = new HttpRequestMessage(HttpMethod.Get, resourceUrl);
	if (null != range)
		request.Headers.Range = new RangeHeaderValue(range.From, range.To);            

	var client = new HttpClient();
	var response = client.SendAsync(request).ContinueWith<HttpResponseMessage>(t => {
		var finalResp = new HttpResponseMessage(HttpStatusCode.OK);

		finalResp.Content = t.Result.Content;

		if (null != range)                       
			finalResp.StatusCode = HttpStatusCode.PartialContent;              

		return finalResp;
	});
	return response;
}

private static RangeHeaderValue ExtractRange(HttpRequestHeaders headers)
{
    if (null == headers)
        throw new ArgumentNullException("headers");
    
    const int readStreamBufferSize = 1024 * 1024;

    var hasRange = (null != headers.Range && headers.Range.Ranges.Any());
    var rangeHeader = hasRange ? headers.Range : new RangeHeaderValue(0, readStreamBufferSize);
    if (!hasRange)
        return rangeHeader;

    // it is better to limit the request to a specific range in order to do no have an out-of-memory exception
    var range = rangeHeader.Ranges.ElementAt(0);
    var from = range.From.GetValueOrDefault(0);
    rangeHeader = new RangeHeaderValue(@from, @from + range.To.GetValueOrDefault(readStreamBufferSize));
    return rangeHeader;
}