如何捕获ConfigurationErrorsException违反maxRequestLength？ [英] How to catch ConfigurationErrorsException for violating maxRequestLength?

问题描述

我限制文件大小，用户可以从Web.config上传到站点。如这里所述，如果不接受尺寸，它应该抛出一个ConfigurationErrorsException 。我试图从动作方法或控制器捕获上传请求，但没有运气。连接已重置，我无法显示错误页面。

I am limiting file size users can upload to the site from Web.config. As explained here, it should throw a ConfigurationErrorsException if size is not accepted. I tried to catch it from the action method or controller for upload requests but no luck. Connection is resetted and I can't get it to show an error page.

我尝试在BeginRequest事件中捕捉它，但无论我做了什么异常都是未处理的。
这里是代码：

I tried catching it in BeginRequest event but no matter what I do the exception is unhandled. Here's the code:

protected void Application_BeginRequest(Object sender, EventArgs e)
{
    HttpContext context = ((HttpApplication)sender).Context;
    try
    {
        if (context.Request.ContentLength > maxRequestLength)
        {
            IServiceProvider provider = (IServiceProvider)context;
            HttpWorkerRequest workerRequest = (HttpWorkerRequest)provider.GetService(typeof(HttpWorkerRequest));

            // Check if body contains data
            if (workerRequest.HasEntityBody())
            {
                // get the total body length
                int requestLength = workerRequest.GetTotalEntityBodyLength();
                // Get the initial bytes loaded
                int initialBytes = 0;
                if (workerRequest.GetPreloadedEntityBody() != null)
                    initialBytes = workerRequest.GetPreloadedEntityBody().Length;
                if (!workerRequest.IsEntireEntityBodyIsPreloaded())
                {
                    byte[] buffer = new byte[512];
                    // Set the received bytes to initial bytes before start reading
                    int receivedBytes = initialBytes;
                    while (requestLength - receivedBytes >= initialBytes)
                    {
                        // Read another set of bytes
                        initialBytes = workerRequest.ReadEntityBody(buffer, buffer.Length);

                        // Update the received bytes
                        receivedBytes += initialBytes;
                    }
                    initialBytes = workerRequest.ReadEntityBody(buffer, requestLength - receivedBytes);
                }
            }
        }
    }
    catch(HttpException)
    {
        context.Response.Redirect(this.Request.Url.LocalPath + "?action=exception");
    }
}

但我还是得到这个：

Maximum request length exceeded.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Web.HttpException: Maximum request length exceeded.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

更新：

什么方法引发异常？如果我读请求，它会引发异常如果我根本看不到，我在浏览器中得到101连接重置。在这里可以做些什么？

What method raises the exception anyway? If I read the request it raises exception If I don't read it at all, I get "101 Connection Reset" in browser. What can be done here?

推荐答案

没有客户端帮助，没有办法做到这一点。您无法确定请求是否太长，除非您读取所有请求。如果您读取每个请求到最后，任何人都会来，并保持您的服务器繁忙。如果你只是看内容长度并放弃请求，另一方面会考虑有一个连接问题。您可以使用错误处理无效，这是HTTP的一个缺点。

There is no way to do it right without a client-side help. You cannot determine if the request is too long unless you read all of it. If you read each request to the end, anyone come and keep your server busy. If you just look at content length and drop the request, other side is going to think there is a connection problem. It's nothing you can do with error handling, it's a shortcoming of HTTP.

您可以使用Flash或Javascript组件使其正确，因为这件事情不能很好地失败。

You can use Flash or Javascript components to make it right because this thing can't fail nicely.

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