protected override DownloadSummary DownloadCore(Uri uri, Stream outputStream, ProgressUpdateCallback progress,
CancellationToken cancellationToken, IComponent?component)
{
var summary = new DownloadSummary();
using var webResponse = GetWebResponse(uri, ref summary, out var webRequest, cancellationToken);
if (webResponse != null)
{
var registration1 = cancellationToken.Register(() => webResponse.Close());
try
{
using var responseStream = webResponse.GetResponseStream();
var header = webResponse.Headers["Content-Length"];
if (string.IsNullOrEmpty(header))
{
throw new IOException("Error: Content-Length is missing from response header.");
}
var totalStreamLength = (long)Convert.ToInt32(header);
if (totalStreamLength.Equals(0L))
{
throw new IOException("Error: Response stream length is 0.");
}
var streamReadError = false;
var totalBytesRead = 0L;
var array = new byte[Math.Max(1024L, Math.Min(totalStreamLength, 32768L))];
var registration2 = cancellationToken.Register(() => webRequest.Abort());
try
{
while (true)
{
cancellationToken.ThrowIfCancellationRequested();
var bytesRead = responseStream.Read(array, 0, array.Length);
streamReadError = bytesRead < 0;
if (bytesRead <= 0)
{
break;
}
totalBytesRead += bytesRead;
outputStream.Write(array, 0, bytesRead);
if (totalStreamLength < totalBytesRead)
{
totalStreamLength = totalBytesRead;
}
progress?.Invoke(new ProgressUpdateStatus(totalBytesRead, totalStreamLength, 0));
}
}
finally
{
registration2.Dispose();
}
cancellationToken.ThrowIfCancellationRequested();
if (streamReadError)
{
throw new IOException("Internal error while downloading the stream.");
}
summary.DownloadedSize = totalBytesRead;
return(summary);
}
catch (WebException ex)
{
var message = cancellationToken.IsCancellationRequested
? "DownloadCore failed along with a cancellation request."
: "DownloadCore failed";
if (cancellationToken.IsCancellationRequested)
{
Logger.Trace("WebClient error '" + ex.Status + "' with '" + uri.AbsoluteUri + "' - " +
message);
cancellationToken.ThrowIfCancellationRequested();
}
else
{
Logger.Trace("WebClient error '" + ex.Status + "' with '" + uri.AbsoluteUri + "'.");
throw;
}
}
finally
{
registration1.Dispose();
}
}
return(summary);
}
private HttpWebResponse?GetWebResponse(Uri uri, ref DownloadSummary summary, out HttpWebRequest webRequest, CancellationToken cancellationToken)
{
var proxyResolution = ProxyResolution.Default;
while (proxyResolution != ProxyResolution.Error)
{
HttpWebResponse?httpWebResponse = null;
var successful = true;
try
{
webRequest = (HttpWebRequest)WebRequest.Create(uri);
webRequest.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
webRequest.Headers.Add("Accept-Encoding", "gzip,deflate");
webRequest.KeepAlive = true;
webRequest.Timeout = 120000;
var requestCachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
webRequest.CachePolicy = requestCachePolicy;
switch (proxyResolution)
{
case ProxyResolution.DefaultCredentialsOrNoAutoProxy:
webRequest.UseDefaultCredentials = true;
break;
case ProxyResolution.NetworkCredentials:
webRequest.UseDefaultCredentials = false;
webRequest.Proxy = WebRequest.GetSystemWebProxy();
webRequest.Proxy.Credentials = CredentialCache.DefaultNetworkCredentials;
break;
case ProxyResolution.DirectAccess:
webRequest.Proxy = null;
break;
}
var registerWebRequest = webRequest;
using (cancellationToken.Register(() => registerWebRequest.Abort()))
httpWebResponse = (HttpWebResponse)webRequest.GetResponse();
var responseUri = httpWebResponse.ResponseUri.ToString();
if (!string.IsNullOrEmpty(responseUri) &&
!uri.ToString().EndsWith(responseUri, StringComparison.InvariantCultureIgnoreCase))
{
summary.FinalUri = responseUri;
Logger.Trace($"Uri '{uri}' + redirected to '{responseUri}'");
}
switch (httpWebResponse.StatusCode)
{
case HttpStatusCode.OK:
summary.ProxyResolution = proxyResolution.ToString();
successful = false;
return(httpWebResponse);
case HttpStatusCode.UseProxy:
case HttpStatusCode.ProxyAuthenticationRequired:
case HttpStatusCode.GatewayTimeout:
++proxyResolution;
if (proxyResolution == ProxyResolution.Error)
{
Logger?.Trace($"WebResponse error '{httpWebResponse.StatusCode}' with '{uri}'.");
_helper.ThrowWrappedWebException((int)httpWebResponse.StatusCode, "WebRequest.GetResponse", summary.FinalUri);
continue;
}
Logger.Trace($"WebResponse error '{httpWebResponse.StatusCode}' - '{uri.AbsoluteUri}'. Reattempt with proxy set to '{proxyResolution}'");
continue;
default:
proxyResolution = ProxyResolution.Error;
Logger.Trace($"WebResponse error '{httpWebResponse.StatusCode}' - '{uri.AbsoluteUri}'.");
_helper.ThrowWrappedWebException((int)httpWebResponse.StatusCode, "WebRequest.GetResponse", summary.FinalUri);
continue;
}
}
catch (WrappedWebException ex)
{
if (proxyResolution == ProxyResolution.Error)
{
Logger.Debug($"WebResponse exception '{ex.Status}' with '{uri}'.");
throw;
}
}
catch (WebException ex)
{
var errorMessage = cancellationToken.IsCancellationRequested ? "GetWebResponse failed along with a cancellation request" : "GetWebResponse failed";
if (cancellationToken.IsCancellationRequested)
{
Logger.Trace("WebClient error '" + ex.Status + "' with '" + uri.AbsoluteUri + "' - " + errorMessage);
cancellationToken.ThrowIfCancellationRequested();
}
Logger.Trace("WebClient error '" + ex.Status + "' - proxy setting '" + proxyResolution + "' - '" + uri.AbsoluteUri + "'.");
switch (ex.Status)
{
case WebExceptionStatus.NameResolutionFailure:
case WebExceptionStatus.ConnectFailure:
case WebExceptionStatus.SendFailure:
case WebExceptionStatus.ProtocolError:
case WebExceptionStatus.ProxyNameResolutionFailure:
++proxyResolution;
break;
default:
proxyResolution = ProxyResolution.Error;
break;
}
if (proxyResolution == ProxyResolution.Error)
{
Logger.Trace("WebClient failed in '" + uri.AbsoluteUri + "' with '" + ex.Message + "' - '" + uri.AbsoluteUri + "'.");
throw;
}
}
catch (Exception ex)
{
Logger?.Debug(ex, "General exception error in web client.");
throw;
}
finally
{
if (httpWebResponse != null && successful)
{
httpWebResponse.Close();
}
}
}
webRequest = null;
return(null);
}