private bool GetProxyForUrl(Uri url, out string?proxyHost, out string?bypass)
{
proxyHost = null;
bypass = null;
var handle = WinHttpOpen(
IntPtr.Zero,
WINHTTP_ACCESS_TYPE_NO_PROXY,
WINHTTP_NO_PROXY_NAME,
WINHTTP_NO_PROXY_BYPASS,
0);
try
{
var _proxyHelper = new WinInetProxyHelper();
if (_proxyHelper.GetProxyForUrl(handle, url, out WINHTTP_PROXY_INFO info))
{
proxyHost = Marshal.PtrToStringAuto(info.Proxy);
bypass = Marshal.PtrToStringAuto(info.ProxyBypass);
return(true);
}
return(false);
}
finally
{
handle.Close();
}
}
/// <summary>
/// Gets the proxy URI. (IWebProxy interface)
/// </summary>
public Uri GetProxy(Uri uri)
{
// We need WinHTTP to detect and/or process a PAC (JavaScript) file. This maps to
// "Automatically detect settings" and/or "Use automatic configuration script" from IE
// settings. But, calling into WinHTTP can be slow especially when it has to call into
// the out-of-process service to discover, load, and run the PAC file. So, we skip
// calling into WinHTTP if there was a recent failure to detect a PAC file on the network.
// This is a common error. The default IE settings on a Windows machine consist of the
// single checkbox for "Automatically detect settings" turned on and most networks
// won't actually discover a PAC file on the network since WPAD protocol isn't configured.
if (_proxyHelper.AutoSettingsUsed && !_proxyHelper.RecentAutoDetectionFailure)
{
var proxyInfo = new Interop.WinHttp.WINHTTP_PROXY_INFO();
try
{
if (_proxyHelper.GetProxyForUrl(_sessionHandle, uri, out proxyInfo))
{
// If WinHTTP just specified a Proxy with no ProxyBypass list, then
// we can return the Proxy uri directly.
if (proxyInfo.ProxyBypass == IntPtr.Zero)
{
return(GetUriFromString(Marshal.PtrToStringUni(proxyInfo.Proxy)));
}
// A bypass list was also specified. This means that WinHTTP has fallen back to
// using the manual IE settings specified and there is a ProxyBypass list also.
// Since we're not really using the full WinHTTP stack, we need to use HttpSystemProxy
// to do the computation of the final proxy uri merging the information from the Proxy
// and ProxyBypass strings.
}
else
{
return(null);
}
}
finally
{
Marshal.FreeHGlobal(proxyInfo.Proxy);
Marshal.FreeHGlobal(proxyInfo.ProxyBypass);
}
}
// Fallback to manual settings if present.
if (_proxyHelper.ManualSettingsUsed)
{
if (_bypassLocal)
{
IPAddress address = null;
if (uri.IsLoopback)
{
// This is optimization for loopback addresses.
// Unfortunately this does not work for all local addresses.
return(null);
}
// Pre-Check if host may be IP address to avoid parsing.
if (uri.HostNameType == UriHostNameType.IPv6 || uri.HostNameType == UriHostNameType.IPv4)
{
// RFC1123 allows labels to start with number.
// Leading number may or may not be IP address.
// IPv6 [::1] notation. '[' is not valid character in names.
if (IPAddress.TryParse(uri.IdnHost, out address))
{
// Host is valid IP address.
// Check if it belongs to local system.
foreach (IPAddress a in _localIp)
{
if (a.Equals(address))
{
return(null);
}
}
}
}
if (uri.HostNameType != UriHostNameType.IPv6 && !uri.IdnHost.Contains('.'))
{
// Not address and does not have a dot.
// Hosts without FQDN are considered local.
return(null);
}
}
// Check if we have other rules for bypass.
if (_bypass != null)
{
foreach (Regex entry in _bypass)
{
// IdnHost does not have [].
if (entry.IsMatch(uri.IdnHost))
{
return(null);
}
}
}
// We did not find match on bypass list.
return((uri.Scheme == "https" || uri.Scheme == "wss") ? _secureProxyUri : _insecureProxyUri);
}
return(null);
}