public void GetProxyForUrl(SafeWinHttpHandle sessionHandle, Uri uri, out Interop.WinHttp.WINHTTP_PROXY_INFO proxyInfo)
{
Interop.WinHttp.WINHTTP_AUTOPROXY_OPTIONS autoProxyOptions;
autoProxyOptions.AutoConfigUrl = AutoConfigUrl;
autoProxyOptions.AutoDetectFlags = AutoDetect ? (Interop.WinHttp.WINHTTP_AUTO_DETECT_TYPE_DHCP | Interop.WinHttp.WINHTTP_AUTO_DETECT_TYPE_DNS_A) : 0;
autoProxyOptions.AutoLoginIfChallenged = false;
autoProxyOptions.Flags =
(AutoDetect ? Interop.WinHttp.WINHTTP_AUTOPROXY_AUTO_DETECT : 0) |
(!string.IsNullOrEmpty(AutoConfigUrl) ? Interop.WinHttp.WINHTTP_AUTOPROXY_CONFIG_URL : 0);
autoProxyOptions.Reserved1 = IntPtr.Zero;
autoProxyOptions.Reserved2 = 0;
// AutoProxy Cache.
// http://msdn.microsoft.com/en-us/library/windows/desktop/aa383153(v=vs.85).aspx
// If the out-of-process service is active when WinHttpGetProxyForUrl is called, the cached autoproxy
// URL and script are available to the whole computer. However, if the out-of-process service is used,
// and the fAutoLogonIfChallenged flag in the pAutoProxyOptions structure is true, then the autoproxy
// URL and script are not cached. Therefore, calling WinHttpGetProxyForUrl with the fAutoLogonIfChallenged
// member set to TRUE results in additional overhead operations that may affect performance.
// The following steps can be used to improve performance:
// 1. Call WinHttpGetProxyForUrl with the fAutoLogonIfChallenged parameter set to false. The autoproxy
// URL and script are cached for future calls to WinHttpGetProxyForUrl.
// 2. If Step 1 fails, with ERROR_WINHTTP_LOGIN_FAILURE, then call WinHttpGetProxyForUrl with the
// fAutoLogonIfChallenged member set to TRUE.
var repeat = false;
do
{
if (Interop.WinHttp.WinHttpGetProxyForUrl(sessionHandle, uri.AbsoluteUri, ref autoProxyOptions, out proxyInfo))
{
repeat = false;
}
else
{
var lastError = Marshal.GetLastWin32Error();
if (lastError == Interop.WinHttp.ERROR_WINHTTP_AUTODETECTION_FAILED)
{
// Fall back to manual settings if available.
if (!string.IsNullOrEmpty(Proxy))
{
proxyInfo.AccessType = Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY;
proxyInfo.Proxy = Marshal.StringToHGlobalUni(Proxy);
proxyInfo.ProxyBypass = string.IsNullOrEmpty(ProxyBypass) ? IntPtr.Zero : Marshal.StringToHGlobalUni(ProxyBypass);
}
else
{
proxyInfo.AccessType = Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY;
proxyInfo.Proxy = IntPtr.Zero;
proxyInfo.ProxyBypass = IntPtr.Zero;
}
repeat = false;
}
else if (lastError == Interop.WinHttp.ERROR_WINHTTP_LOGIN_FAILURE)
{
if (repeat)
{
throw WinHttpException.CreateExceptionUsingError(lastError);
}
repeat = true;
autoProxyOptions.AutoLoginIfChallenged = true;
}
else
{
WinHttpException.ThrowExceptionUsingLastError();
}
}
} while (repeat);
}
public bool GetProxyForUrl(
SafeWinHttpHandle sessionHandle,
Uri uri,
out Interop.WinHttp.WINHTTP_PROXY_INFO proxyInfo)
{
proxyInfo.AccessType = Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY;
proxyInfo.Proxy = IntPtr.Zero;
proxyInfo.ProxyBypass = IntPtr.Zero;
if (!_useProxy)
{
return(false);
}
bool useProxy = false;
Interop.WinHttp.WINHTTP_AUTOPROXY_OPTIONS autoProxyOptions;
autoProxyOptions.AutoConfigUrl = AutoConfigUrl;
autoProxyOptions.AutoDetectFlags = AutoDetect ?
(Interop.WinHttp.WINHTTP_AUTO_DETECT_TYPE_DHCP | Interop.WinHttp.WINHTTP_AUTO_DETECT_TYPE_DNS_A) : 0;
autoProxyOptions.AutoLoginIfChallenged = false;
autoProxyOptions.Flags =
(AutoDetect ? Interop.WinHttp.WINHTTP_AUTOPROXY_AUTO_DETECT : 0) |
(!string.IsNullOrEmpty(AutoConfigUrl) ? Interop.WinHttp.WINHTTP_AUTOPROXY_CONFIG_URL : 0);
autoProxyOptions.Reserved1 = IntPtr.Zero;
autoProxyOptions.Reserved2 = 0;
// AutoProxy Cache.
// http://msdn.microsoft.com/en-us/library/windows/desktop/aa383153(v=vs.85).aspx
// If the out-of-process service is active when WinHttpGetProxyForUrl is called, the cached autoproxy
// URL and script are available to the whole computer. However, if the out-of-process service is used,
// and the fAutoLogonIfChallenged flag in the pAutoProxyOptions structure is true, then the autoproxy
// URL and script are not cached. Therefore, calling WinHttpGetProxyForUrl with the fAutoLogonIfChallenged
// member set to TRUE results in additional overhead operations that may affect performance.
// The following steps can be used to improve performance:
// 1. Call WinHttpGetProxyForUrl with the fAutoLogonIfChallenged parameter set to false. The autoproxy
// URL and script are cached for future calls to WinHttpGetProxyForUrl.
// 2. If Step 1 fails, with ERROR_WINHTTP_LOGIN_FAILURE, then call WinHttpGetProxyForUrl with the
// fAutoLogonIfChallenged member set to TRUE.
//
// We match behavior of WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY and ignore errors.
var repeat = false;
do
{
_autoDetectionFailed = false;
if (Interop.WinHttp.WinHttpGetProxyForUrl(
sessionHandle,
uri.AbsoluteUri,
ref autoProxyOptions,
out proxyInfo))
{
WinHttpTraceHelper.Trace("WinInetProxyHelper.GetProxyForUrl: Using autoconfig proxy settings");
useProxy = true;
break;
}
else
{
var lastError = Marshal.GetLastWin32Error();
WinHttpTraceHelper.Trace("WinInetProxyHelper.GetProxyForUrl: error={0}", lastError);
if (lastError == Interop.WinHttp.ERROR_WINHTTP_LOGIN_FAILURE)
{
if (repeat)
{
// We don't retry more than once.
break;
}
else
{
repeat = true;
autoProxyOptions.AutoLoginIfChallenged = true;
}
}
else
{
if (lastError == Interop.WinHttp.ERROR_WINHTTP_AUTODETECTION_FAILED)
{
_autoDetectionFailed = true;
_lastTimeAutoDetectionFailed = Environment.TickCount;
}
break;
}
}
} while (repeat);
// Fall back to manual settings if available.
if (!useProxy && !string.IsNullOrEmpty(Proxy))
{
proxyInfo.AccessType = Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY;
proxyInfo.Proxy = Marshal.StringToHGlobalUni(Proxy);
proxyInfo.ProxyBypass = string.IsNullOrEmpty(ProxyBypass) ?
IntPtr.Zero : Marshal.StringToHGlobalUni(ProxyBypass);
WinHttpTraceHelper.Trace(
"WinInetProxyHelper.GetProxyForUrl: Fallback to Proxy={0}, ProxyBypass={1}",
Proxy,
ProxyBypass);
useProxy = true;
}
WinHttpTraceHelper.Trace("WinInetProxyHelper.GetProxyForUrl: useProxy={0}", useProxy);
return(useProxy);
}
private void SetRequestHandleProxyOptions(WinHttpRequestState state)
{
// We've already set the proxy on the session handle if we're using no proxy or default proxy settings.
// We only need to change it on the request handle if we have a specific IWebProxy or need to manually
// implement Wininet-style auto proxy detection.
if (state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseCustomProxy ||
state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseWinInetProxy)
{
var proxyInfo = new Interop.WinHttp.WINHTTP_PROXY_INFO();
bool updateProxySettings = false;
Uri uri = state.RequestMessage.RequestUri;
try
{
if (state.Proxy != null)
{
Debug.Assert(state.WindowsProxyUsePolicy == WindowsProxyUsePolicy.UseCustomProxy);
updateProxySettings = true;
if (state.Proxy.IsBypassed(uri))
{
proxyInfo.AccessType = Interop.WinHttp.WINHTTP_ACCESS_TYPE_NO_PROXY;
}
else
{
proxyInfo.AccessType = Interop.WinHttp.WINHTTP_ACCESS_TYPE_NAMED_PROXY;
Uri proxyUri = state.Proxy.GetProxy(uri);
string proxyString = string.Format(
CultureInfo.InvariantCulture,
"{0}://{1}",
proxyUri.Scheme,
proxyUri.Authority);
proxyInfo.Proxy = Marshal.StringToHGlobalUni(proxyString);
}
}
else if (_proxyHelper != null && _proxyHelper.AutoSettingsUsed)
{
updateProxySettings = true;
_proxyHelper.GetProxyForUrl(_sessionHandle, uri, out proxyInfo);
}
if (updateProxySettings)
{
GCHandle pinnedHandle = GCHandle.Alloc(proxyInfo, GCHandleType.Pinned);
try
{
SetWinHttpOption(
state.RequestHandle,
Interop.WinHttp.WINHTTP_OPTION_PROXY,
pinnedHandle.AddrOfPinnedObject(),
(uint)Marshal.SizeOf(proxyInfo));
}
finally
{
pinnedHandle.Free();
}
}
}
finally
{
Marshal.FreeHGlobal(proxyInfo.Proxy);
Marshal.FreeHGlobal(proxyInfo.ProxyBypass);
}
}
}
