Start Validating filenames with regularexpressionvalidator

Validating filenames with regularexpressionvalidator

NET Machine Account under the Security tab, you can add it by clicking the Add button and entering ASPNET (without the period) in the text area, as illustrated in Figure 2. The Submit button on the page causes the Button1_Click event to occur. File Name) & _ "" End If Catch ex As Exception Label1. Message End Try i = 1 Loop End Sub The end user can select up to four files and click the Upload Files button, which initializes the Button1_Click event.

Note The use of validation controls is not explained here. NET Server Controls for a complete explanation of validation controls and how to use them in your ASP. If the file type is not one these three choices, a Validation control throws an exception onto the screen. It wouldn't be too hard for someone to change the file extension of a file so it would be accepted and uploaded to the server, thereby bypassing this simple security model. Now let's take a look at how to perform a similar operation on the server-side.

In this article I explain validation with a file upload control using regular expression validation control in ASP. This article will help you to validate the extension of a file to be uploaded before the file is uploaded in ASP. Description Usually for checking the desired file extensions in a file upload control we use C# code to determine whether the file extension is valid or not.

If you want to apply this to only the application you are working with, apply this node to the web.config file of your application, overriding any setting that is in the web.config.comments file. The value given the execution Timeout attribute is the number of seconds the upload is allowed to occur before being shut down by ASP. If you are going to allow large files to be uploaded to the server, you are also going to want to increase this value along with the max Request Length value. Content Length & " kb" & _ "Content type: " & _ File Upload1. Files Dim i As Integer = 0 Do Until i = uploaded Files.

NET 2.0 configuration folder at C:\WINDOWS\Microsoft. NET\Framework\v2.0.50727\CONFIG) or your application's web.config file. In the web.config.comments file, find a node called A lot is going on in this single node, but the setting that takes care of the size of the files to be uploaded is the max Request Length attribute. Simply change this value to increase the size of the files that you can upload to the server. Now let's take a look at how to upload multiple files to the server from a single page. NET Framework enable you to upload multiple files from a single ASP. With a little work, however, you can easily accomplish this task just as you would have in the past using . If you wanted to, you could simply handle each and every File Upload control on the page individually, as presented in Listing 5. Handling each File Upload control individually Visual Basic This approach works, but there may be instances where you are going to want to handle the files using the Http File Collection class instead—especially if you are working with a dynamically generated list of server controls. NET page that has three File Upload controls and one Submit button (using the Button control). About the author Bill Evjen is an active proponent of .

Unfortunately, there is no bullet-proof method to protect you from someone uploading files that would be considered malicious.

You can take a few steps, however, to make this process of allowing end users to upload files a little more manageable. NET validation controls that are provided for free with ASP. These controls enable you to do a regular-expression check upon the file that is being uploaded to see if the extension of the file is one you permit to be uploaded. File Name) If (file Ext = ".mp3") Then Try File Upload1.

I previously wrote an MSDN article on how to effectively use this control in your ASP. This article is a reintroduction to the file upload process, but instead of using the File Field control, I will show you how to effectively use the new File Upload server control that is offered through ASP. It is important to note that while this article introduces you to the new File Upload server control, it is still quite possible to use the File Field control in your applications today. There are some important items we should go over for this example so you understand all the needed pieces to make this work.