Why Should You Use `exit()` After `header()` Redirection in PHP?

Why the 'exit' Call is Crucial After Header Redirection in PHP

PHP's header function allows redirection of users. However, it's a common practice to include an exit statement after the header call to prevent subsequent PHP code execution. This raises the question: can code after the header redirection be executed?

Can Code After the Header Redirection Execute?

Yes, any code after a header redirection can still be executed. The header is merely a request to the browser to redirect the user. The PHP script continues to process the rest of the page and send it along with the response.

How Can Code Continue Executing?

Clients can prevent the header's execution by using command-line tools like wget. By disabling automatic redirection, clients can access the entire page output.

Implications for Security

A malicious user could take advantage of this behavior and potentially ignore the header redirection. By disabling redirection, they could gain access to sensitive information or execute malicious code.

Prevention Techniques

To prevent code execution after a header redirection:

• Use the exit statement after the header call.
• Set the necessary HTTP headers (e.g., Content-Length) to ensure a complete response is sent.
• Use an alternative approach to redirection, such as JavaScript.

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