private HttpWebResponse GetOrCreateWebStream()
{
if (lastResponse != null)
{
return(lastResponse);
}
HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(Uri);
if (Progress > 0)
{
httpRequest.AddRange(Progress);
}
lastResponse = GetUnredirectedResponse(httpRequest);
// The content disposition header will often contain the filename of the download
// We can use this to update the output filename in the case of redirects
var contentDispositionHeader = lastResponse.Headers.Get("Content-Disposition");
if (!string.IsNullOrEmpty(contentDispositionHeader))
{
ContentDisposition contentDisposition = new ContentDisposition(contentDispositionHeader);
ResponseFilename = contentDisposition.FileName;
ReceivedResponseFilename?.Invoke(this, new ResponseFilenameEventArgs(ResponseFilename));
}
return(lastResponse);
}
private HttpWebResponse GetUnredirectedResponse(WebRequest req)
{
try
{
var res = req.GetResponse();
return((HttpWebResponse)res);
}
catch (WebException ex)
{
// We have to manually deal with redirects here because .NET Core does not
// auto redirect https to http in the name of safety. While this is a noble
// effort, and probably the correct to handle it, unfortunately some sites
// do not do this and redirect down to http. So this will hopefully handle
// that.
var httpResp = ((HttpWebResponse)ex.Response);
if ((int)httpResp.StatusCode >= 300 && (int)httpResp.StatusCode < 400)
{
var redirect = httpResp.GetResponseHeader("Location");
if (!string.IsNullOrEmpty(redirect))
{
Log.WriteLine("Following redirect to: " + redirect);
var newUrl = new Uri(redirect);
var newFn = newUrl.Segments.Last();
ReceivedResponseFilename?.Invoke(this, new ResponseFilenameEventArgs(HttpUtility.UrlDecode(newFn)));
HttpWebRequest newRequest = (HttpWebRequest)WebRequest.Create(newUrl);
if (Progress > 0)
{
newRequest.AddRange(Progress);
}
return(GetUnredirectedResponse(newRequest));
}
}
// Rethrow error if it's not a 300-type redirect
throw ex;
}
}
