How Can I Reliably Determine HTTPS Connection Status in PHP?

Determining HTTPS Connection Status Beyond $_SERVER['HTTPS']

Many online tutorials suggest checking $_SERVER['HTTPS'] to ascertain whether a server connection is secured via HTTPS. However, $_SERVER['HTTPS'] may not be defined on certain servers, leading to errors.

Alternative Variable for HTTPS Detection

To overcome this issue, consider using the isSecure() function, which provides a reliable indication of HTTPS connection status even when $_SERVER['HTTPS'] is undefined:

function isSecure() {
  return
    (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off')
    || $_SERVER['SERVER_PORT'] == 443;
}

Compatibility and Considerations

• IIS Compatibility: This function works with IIS servers.
• **Undefinded $_SERVER['HTTPS']:** Despite documentation stating that $_SERVER['HTTPS'] should be set for HTTPS connections, it may be undefined with certain configurations.
• Apache 1.x Servers: Apache 1.x servers may not define $_SERVER['HTTPS'] for secure connections.
• Port 443 Check: Convention suggests that connections made on port 443 typically use secure sockets.

Load Balancer and HTTP_X_FORWARDED_PROTO

Note that this function does not test the connection between the client and a potential load balancer. To check this, the HTTP_X_FORWARDED_PROTO header can be utilized, but its implementation is more complex.

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