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ASP ( Active Server Pages )

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Login & Session Control     

Checking the session presence in ASP

We can display a welcome message to a visitor inside a member area based on his session status. If the member has not logged in then we can ask him to login. You must have observed in many sites and forums you will get a welcome message if you are logged in and the same place will show login form or link to login form if you are not logged in. How this is done ? We will learn that.

If the member is logged in then userid of the member will be available in session variable. So we will try to read the value of the session variable and display a welcome message like this Welcome smo

If session variable is not present then we will display a login window or show a link to login page like his   

Userid
Passwor
            

We will be using one if condition in ASP to check the session and display the welcome message if userid is present , else we will show the login form. Here is the code to do this
 

Creating Login form and validation using ASP MSSQL

Try to develop a login page using ASP. Actually we will be displaying one html login form to the visitor to enter their userid and password and from ASP side code is not there but using ASP we will check the session values to find out whether the member is already logged in or this is a fresh login.


Read the detail on how to check session login status and display login form.


The login page has very simple code and through this page we will collect userid and password and then send the data by form post method to another page where we will do the matching from our MSSQL table. Here is the code for login page.
 

Once the userid and password is entered by the member in login form and submitted the value is collected at action page.

Dim userid,password
userid=Request("userid")
password=Request("password")

Now the userid and password are stored in the variables. We have to take care of this data as other than characters and numbers are not allowed in these two fields. We have to validate these data before matching them with our database table. This is also a security requirement to prevent injection attack. We will use regular expression to check our user entered data. We will use one if condition for validation and once the validation is ok then only the code inside the if block will be executed. Here is the code.
 

The code after ( within ) the if then condition will be executed once the regular expression validation is passed. In the else block of the code we will keep the message to be displayed if the validation fails. That part is not shown in the above code. You can see that message in full code given at the end. Now let us work on how to match the record in MSSQL table with the user entered data. We have not displayed the MSSQL connection etc and here is the code for matching record.

The above code will match the data with table and display the error message if matching fails. Otherwise if login details are correct then a new session with userid is created. Next we will read how to create member pages and other parts of login script. Here is the complete code.

 

Restricting access to member area in ASP

We can create a member only area in asp by using sessions. Userid of the member is stored in session variable and presence of this session variable is checked at the beginning of each page inside the member area. If session with userid is available then further script execution is allowed, otherwise the script execution is stopped and a message asking the member to login is displayed.

The session for every member is created at login page where a session with userid of the member is created after successful login of the member.

This member area pages links we can display once a member is successfully logged in but members may bookmark the URL of member area and may try to access the member area pages without logging in so session checking is a must for all these restricted pages.

We have to keep this checking if session status at the top of each page, here a better idea is to keep all these code inside one file and include that file at the staring of each page of member area. Like this ..
Now inside this check.asp file we will keep the code to check the user session status. Here it is .
 

You can see in the above code if the Session(“userid”) is not available then IsEmpty function will return true and the code inside the if condition will be executed. The fist line will display the message with a link to login page and the next line Rsponse.End will stop further execution of the page.

This is a simple way to restrict access inside member only page for logged in users only.

Updating password in login script using ASP MSSQL

We will add change password feature to our login script. This page to update password is available only to successfully logged in users or members so we will keep this page inside our members only area.

Link to this change password page we will add to our top menu file. This menu.asp file is kept inside the member area and as we add different files to the member area we will be adding links inside this menu.asp file. All the files to display this menu has to include this menu.asp file. Like this

We will ask member to enter the new password twice and for this we will display a form. In this form we will ask the user to enter new password two times. This is a simple form and only html code is used to display this. Here is the code to display the form.

 

Once the above form is submitted we will check the entered password for two conditions. First it should match our requirement of only number and characters of 3 to 8 char length. Second both the entered passwords should be same. For our first condition checking we will use regular expression and for second condition it is simple string matching. Here we will use two variables one for error flag and other for error message. Error flag we will set to True if any error occurs and we will add the corresponding message to error message variable. At the end if error message flag is not set to true then we will update the table with new password for the particular user id . Here is the complete code.