mrcgrtz/ping-example.html

## ping-example.html
<!doctype html>
<meta charset="utf-8">
<title>Ping Test</title>

<p>Click this <a href="https://example.com" ping="/ping.php">test link</a>.

## ping.php
<?php

declare(strict_types=1);

// Configuration: Set allowed host.
$host = 'https://my.host';

// Configuration: Set mail from/to.
$from = $_SERVER['SERVER_ADMIN'];
$to = $_SERVER['SERVER_ADMIN'];

// Get the Ping-From header value.
$headers = apache_request_headers() ?? [];
$url = $headers['Ping-From'] ?? '';

// Check for a valid ping from my host.
if (!empty($url) && str_starts_with($url, $host)) {
	// Prepare the mail.
	$subject = 'Ping';
    $headers = [
        'MIME-Version' => '1.0',
		'Content-Type' => 'text/plain; charset="utf-8"',
		'Content-Transfer-Encoding' => '8bit',
		'From' => $from,
		'X-Mailer' => 'PHP/' . phpversion(),
    ];
	$body = implode("\r\n", [
		'Ping from: ' . $url,
		'Date/time: ' . strftime('%c'),
	]);
	// Mail the ping.
	if (!mail($to, $subject, $body, $headers)) {
		// Sending a mail did not work, respond with server error.
		http_response_code(500);
		exit();
	}
	// Sending the mail worked, a ping mail was created.
	http_response_code(201);
	exit();
}

// The request was bad.
http_response_code(400);
	<!doctype html>
	<meta charset="utf-8">
	<title>Ping Test</title>

	<p>Click this <a href="https://example.com" ping="/ping.php">test link</a>.
	<?php

	declare(strict_types=1);

	// Configuration: Set allowed host.
	$host = 'https://my.host';

	// Configuration: Set mail from/to.
	$from = $_SERVER['SERVER_ADMIN'];
	$to = $_SERVER['SERVER_ADMIN'];

	// Get the Ping-From header value.
	$headers = apache_request_headers() ?? [];
	$url = $headers['Ping-From'] ?? '';

	// Check for a valid ping from my host.
	if (!empty($url) && str_starts_with($url, $host)) {
	// Prepare the mail.
	$subject = 'Ping';
	$headers = [
	'MIME-Version' => '1.0',
	'Content-Type' => 'text/plain; charset="utf-8"',
	'Content-Transfer-Encoding' => '8bit',
	'From' => $from,
	'X-Mailer' => 'PHP/' . phpversion(),
	];
	$body = implode("\r\n", [
	'Ping from: ' . $url,
	'Date/time: ' . strftime('%c'),
	]);
	// Mail the ping.
	if (!mail($to, $subject, $body, $headers)) {
	// Sending a mail did not work, respond with server error.
	http_response_code(500);
	exit();
	}
	// Sending the mail worked, a ping mail was created.
	http_response_code(201);
	exit();
	}

	// The request was bad.
	http_response_code(400);