private static void OnRequestRedirect(WinHttpRequestState state, Uri redirectUri)
{
const string EmptyCookieHeader = "Cookie:";
Debug.Assert(state != null, "OnRequestRedirect: state is null");
Debug.Assert(redirectUri != null, "OnRequestRedirect: redirectUri is null");
Debug.Assert(state.TcsReceiveResponseHeaders != null, "TcsReceiveResponseHeaders is null");
Debug.Assert(!state.TcsReceiveResponseHeaders.Task.IsCompleted, "TcsReceiveResponseHeaders.Task is completed");
// If we're manually handling cookies, we need to reset them based on the new URI.
if (state.Handler.CookieUsePolicy == CookieUsePolicy.UseSpecifiedCookieContainer)
{
// Clear cookies.
if (!Interop.WinHttp.WinHttpAddRequestHeaders(
state.RequestHandle,
EmptyCookieHeader,
(uint)EmptyCookieHeader.Length,
Interop.WinHttp.WINHTTP_ADDREQ_FLAG_REPLACE))
{
int lastError = Marshal.GetLastWin32Error();
if (lastError != Interop.WinHttp.ERROR_WINHTTP_HEADER_NOT_FOUND)
{
throw WinHttpException.CreateExceptionUsingError(lastError);
}
}
// Re-add cookies. The GetCookieHeader() method will return the correct set of
// cookies based on the redirectUri.
string cookieHeader = WinHttpHandler.GetCookieHeader(redirectUri, state.Handler.CookieContainer);
if (!string.IsNullOrEmpty(cookieHeader))
{
if (!Interop.WinHttp.WinHttpAddRequestHeaders(
state.RequestHandle,
cookieHeader,
(uint)cookieHeader.Length,
Interop.WinHttp.WINHTTP_ADDREQ_FLAG_ADD))
{
WinHttpException.ThrowExceptionUsingLastError();
}
}
}
state.RequestMessage.RequestUri = redirectUri;
// Redirection to a new uri may require a new connection through a potentially different proxy.
// If so, we will need to respond to additional 407 proxy auth demands and re-attach any
// proxy credentials. The ProcessResponse() method looks at the state.LastStatusCode
// before attaching proxy credentials and marking the HTTP request to be re-submitted.
// So we need to reset the LastStatusCode remembered. Otherwise, it will see additional 407
// responses as an indication that proxy auth failed and won't retry the HTTP request.
if (state.LastStatusCode == HttpStatusCode.ProxyAuthenticationRequired)
{
state.LastStatusCode = 0;
}
// For security reasons, we drop the server credential if it is a
// NetworkCredential. But we allow credentials in a CredentialCache
// since they are specifically tied to URI's.
if (!(state.ServerCredentials is CredentialCache))
{
state.ServerCredentials = null;
}
}
