_PageStart.cshtml is not handing exception

dejohnny · June 2nd, 2012, 03:02 PM

I'm on page 226 of the book and I'm puzzled by what's happening when I try to upload a file larger than 4MB.

I did everything exactly as show on page 222, and the code worked as expected. But when I modified the code to use _PageStart.cshtml, all hell broke loose! Instead of getting a nice error page describing the error that was thrown, I'm getting the usual error page that IIS7 displays. What am I missing?

Here are the steps I've gone through to run the site:

Select and run Default.cshtml.
Choose a file larger than 4MB.
Click Upload button and wait.
Result: Standard IIS7 error page.

Quote:

HTTP Error 404.13 - Not Found
The request filtering module is configured to deny a request that exceeds the request content length.

Most likely causes:
Request filtering is configured on the Web server to deny the request because the content length exceeds the configured value.

Things you can try:
Verify the configuration/system.webServer/security/requestFiltering/requestLimits@maxAllowedContentLength setting in the applicationhost.config or web.config file.

Detailed Error Information:
Module RequestFilteringModule
Notification BeginRequest
Handler cshtml-Integrated-4.0
Error Code 0x00000000
Requested URL http://localhost:30844/Default.cshtml
Physical Path C:\Documents and Settings\Darel Johnson\My Documents\My Web Sites\Chapter 9\Default.cshtml
Logon Method Not yet determined
Logon User Not yet determined
Request Tracing Directory C:\Documents and Settings\Darel Johnson\My Documents\IISExpress\TraceLogFiles\CHAPTER 9

More Information:
This is a security feature. Do not change this feature unless the scope of the change is fully understood. You can configure the IIS server to reject requests whose content length is greater than a specified value. If the request's content length is greater than the configured length, this error is returned. If the content length requires an increase, modify the configuration/system.webServer/security/requestFiltering/requestLimits@maxAllowedContentLength setting.
View more information Â»

This error page is not what I'm expecting to see. I was under the impression that I would be able to redirect to Error.cshtml. But that doesn't happen.

web.config

HTML Code:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <!-- Custom Errors -->
  <system.web>
        <compilation debug="false" targetFramework="4.0" />
        <!-- This is commented out
        <customErrors mode="Off" >
            <error statusCode="404" redirect="404.cshtml" />
        </customErrors>
        -->
  </system.web>
  <!-- Email -->
  <system.net>
        <mailSettings>
            <smtp deliveryMethod="SpecifiedPickupDirectory">
                <specifiedPickupDirectory pickupDirectoryLocation="C:\Mail\" />
            </smtp>
        </mailSettings>
  </system.net>
  
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="WebMatrix.WebData" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.WebPages.Razor" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="WebMatrix.Data" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

Default.cshtml

HTML Code:

@{
    /* test Exception handling */
    //throw new NullReferenceException();
    
    var message = "";
    try{
        if(Request.Files.Count > 0 ){
            WebImage image = WebImage.GetImageFromRequest();
            if(image != null){
                message = "Upload succeeded";
            } else {
                message = "You must upload an image file: .jpg, .gif, .png, .bmp, .tif";
            }
        }
    }
    catch(Exception ex){
        message = "Upload unsuccessful because: " + ex.Message;
    }
    
}
<!DOCTYPE html>

<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title></title>
    </head>
    <body>
        <h1>Upload Images</h1>
        <div>@message</div><br/>
        @FileUpload.GetHtml(allowMoreFilesToBeAdded: false)
    </body>
</html>

_PageStart.cshtml

HTML Code:

@{
    /// Catch any errors in Webpages in the same folder or subfolder
    /// and report errors via email
    try{
        RunPage();
    } 
    catch(Exception ex){
        var message = ex.Message + "\n";
        var stack   = ex.StackTrace;
        
        var logEntry = DateTime.Now + "\n" + message + stack;
        logEntry += "\n===============================\n";
        var location = Server.MapPath("~/App_Data");
        var fileName = "errorlog.txt";
        var path = Path.Combine(location, fileName);
        
        File.AppendAllText(path, logEntry);
        WebMail.Send(
            to: "[email protected]", 
            subject: "Error on site: ", 
            body: "The following error occurred\n" + message + stack, 
            isBodyHtml: false
        );
        
        Response.Redirect("~/Error/");
      
    }
    
}

Error.cshtml

HTML Code:

<!DOCTYPE html>

<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title>Error Report Page</title>
    </head>
    <body>
        <h1><span style="color:Orange"><em>Oops!</em></span> An error occurred</h1>
        
    </body>
</html>

Mike Brind · June 3rd, 2012, 07:03 AM

If your upload exceeds 27MB, IIS request filtering kicks in before ASP.NET even gets a chance to object. See step 5 on p. 223.

dejohnny · June 3rd, 2012, 08:30 PM

It looks like I would need to perform a sanity check on any file that gets uploaded then.

We could use the Request object property TotalBytes, to check for the size of the HttpRequest before it gets uploaded.

Also, in this instance, I will not be using _PageStart.cshtml to trap errors from web pages. It doesn't work as expected. I think it's better to handle exceptions on each page individually and then send the errors by calling one function that takes care of logging and emailing.

Solution

Code:

@{
    var pageTitle = "Default Page";
    var message = "";
    
    try{
        /// upload the image, if the byte stream 
        /// is less than 3MB
        if(Request.TotalBytes < 3145728  ){ 
            if(Request.Files.Count > 0 ){
                /// WebImage class only understands the 
                /// properties of binary images
                WebImage image = WebImage.GetImageFromRequest();
                    if(image != null){
                        message = "Upload succeeded";
                    } else {
                        message = "You must upload an image file: .jpg, .gif, .png, .bmp, .tif";
                    }    
			}
        } 
        else {
			message = "You cannot upload files larger than 3MB!";
		}
    }
    catch(Exception ex){
        message = "Upload unsuccessful because: " + ex.Message;
        /// Log errors and send email notifications when errors occur
        Functions.debugNotify( ex, message, pageTitle);
    }
    
}

The only problem with this approach is that, WebImage objects only detect the properties of binary filestreams. This will not work, if for example, you accidentally upload a PDF or exe file. IIS7 will baulk at you with a 404.13 error page if you do that.