/// <summary>
/// Performs the given WebRequestFunction, retrying if an error occurs, and handling
/// proxy authentication.
/// </summary>
/// <param name="func">The WebRequestFunction to execute.</param>
/// <param name="arg">The WebRequestFunction argument.</param>
/// <returns>The WebRequestFunction return value.</returns>
private object PerformWebRequest(WebRequestFunction func, Object arg)
{
int retries = 2;
while (retries-- > 0)
{
try
{
Object ret;
WebException proxyAuthException;
return(ProxyAuthHandler(func, arg, out ret, out proxyAuthException));
}
catch
{
if (retries == 0)
{
throw; // rethrow only if no more retries left
}
}
}
return(null);
}
/// <summary>
/// Performs the actual WebRequestFunction and returns whether or not we require proxy auth.
/// </summary>
/// <returns>True if we received HTTP 407: Proxy Authentication Required.</returns>
private bool IsProxyAuthRequired(WebRequestFunction func, Object arg, out Object ret, out WebException proxyAuthException)
{
try
{
ret = func(arg);
proxyAuthException = null;
return(false);
}
catch (WebException ex)
{
if (ex.Status == WebExceptionStatus.ProtocolError && ((HttpWebResponse)ex.Response).StatusCode == HttpStatusCode.ProxyAuthenticationRequired)
{
// proxy auth required
ret = null;
proxyAuthException = ex;
return(true);
}
else
{
// other error
throw;
}
}
}
/// <summary>
/// If proxy auth is required then the proxy password is retrieved from saved credentials
/// or requested from the user. This is repeated until the WebRequestFunction succeeds
/// (upon which the credentials are saved), or the user cancels.
/// </summary>
private object ProxyAuthHandler(WebRequestFunction func, Object arg, out Object ret, out WebException proxyAuthException)
{
if (!IsProxyAuthRequired(func, arg, out ret, out proxyAuthException))
{
return(ret);
}
// got HTTP 407
// extract realm
string realm = proxyAuthException.Response.Headers[HttpResponseHeader.ProxyAuthenticate];
Match match = Regex.Match(realm, @"realm=\""(.+?)\""", RegexOptions.IgnoreCase); // eg, "Basic realm=\"The realm name\"" (inc quotes)
if (match.Success)
{
realm = match.Groups[1].Value;
}
else if (WebRequest.DefaultWebProxy is WebProxy) // custom
{
realm = ((WebProxy)WebRequest.DefaultWebProxy).Address.Host;
}
else
{
realm = Language.NetManager_PleaseEnterCredentials;
}
// ask for credentials until succeeds or cancelled
while (true)
{
// remove save check if auth failed
if (WebRequest.DefaultWebProxy.Credentials != null)
{
proxyCredDialog.SaveChecked = false;
}
// get proxy credentials (prompt if not stored)
NetworkCredential cred = GetProxyCredentials(realm);
if (cred == null)
{
throw proxyAuthException; // user cancelled, return original 407 exception
}
WebRequest.DefaultWebProxy.Credentials = cred;
// try again
if (!IsProxyAuthRequired(func, arg, out ret, out proxyAuthException)) // success
{
proxyCredDialog.AlwaysDisplay = false;
try
{
if (proxyCredDialog.SaveChecked)
{
proxyCredDialog.Confirm(true); // store
}
else
{
proxyCredDialog.Confirm(false); // unstore
}
}
catch { }
return(ret);
}
else // failed again
{
proxyCredDialog.AlwaysDisplay = true;
proxyCredDialog.Password = "";
try // throws an exception if didn't actually show dialog (ie, stored password was wrong)
{
proxyCredDialog.Confirm(false);
}
catch { }
}
} // end while
}