Learning PHP and MySQL

PHP and HTTP Authentication

PHP can use authentication from the Apache web server. PHP sends a header request to the browser requesting an authentication dialog on the client's browser. You'll recognize this prompt as a standard browser login prompt. Because the authentication head must come before any other HTML output, this works only with the module-based PHP installation, not the CGI version.

Example 13-4 shows how to use HTTP authentication.

Example 13-4. Using HTTP authentication with a PHP script

<?php
if (!isset($_SERVER['PHP_AUTH_USER']) || !isset($_SERVER['PHP_AUTH_PW'])) {
header('WWW-Authenticate: Basic realm="Member Area"');
header("HTTP/1.0 401 Unauthorized");
echo "Please login with a valid username and password.";
exit;
} else {
echo "You entered a username of: ".$_SERVER['PHP_AUTH_USER']." ";
echo "and a password of: ".$_SERVER['PHP_AUTH_PW'].".";
}
?>

The code from Example 13-4 displays a prompt like the one in Figure 13-2.

Figure 13-2. The prompt for authentication to the Member Area realm

If the user clicks Cancel, he'll see Figure 13-3.

Figure 13-3. Clicking Cancel causes a message that the user must log in

That's a fairly simple example. We checked to see if the username and password were set, then displayed them to the user. The realm field provides a way for grouping ...