webhook.php

<?php

// Fill in with your BTCPay Server data.
$secret = "secret"; // webhook secret configured in the BTCPay UI

$myfile = fopen("private/BTCPayIPN.log", "a");

$raw_post_data = file_get_contents('php://input');

$date = date('m/d/Y h:i:s a', time());

if (false === $raw_post_data) {
    fwrite($myfile, $date . " : Error. Could not read from the php://input stream or invalid BTCPayServer IPN received.\n");
    fclose($myfile);
    throw new \Exception('Could not read from the php://input stream or invalid BTCPayServer IPN received.');
}

$ipn = json_decode($raw_post_data);

if (true === empty($ipn)) {
    fwrite($myfile, $date . " : Error. Could not decode the JSON payload from BTCPay.\n");
    fclose($myfile);
    throw new \Exception('Could not decode the JSON payload from BTCPay.');
}

// verify hmac256
$headers = getallheaders();
$sig = $headers['Btcpay-Sig'];

if ($sig != "sha256=" . hash_hmac('sha256', $raw_post_data, $secret)) {
    fwrite($myfile, $date . " : Error. Invalid Signature detected! \n was: " . $sig . " should be: " . hash_hmac('sha256', $raw_post_data, $secret) . "\n");
    fclose($myfile);
    throw new \Exception('Invalid BTCPayServer payment notification message received - signature did not match.');
}


if (true === empty($ipn->invoiceId)) {
    fwrite($myfile, $date . " : Error. Invalid BTCPayServer payment notification message received - did not receive invoice ID.\n");
    fclose($myfile);
    throw new \Exception('Invalid BTCPayServer payment notification message received - did not receive invoice ID.');
}

// optional: check whether your webhook is of the desired type
if ($ipn->type != "InvoiceSettled" && $ipn->type != "InvoiceExpired") {
    throw new \Exception('Invalid IPN Message Type only InvoiceSettled and Expired supported, check configuration of webhook');
}


fwrite($myfile, $date . " : IPN received for BtcPay invoice " . $ipn->invoiceId . " Type: " . $ipn->type . "\n");
fwrite($myfile, "Raw IPN: " . $raw_post_data . "\n");

// your own processing code goes here!
// pass this to worker: $ipn->id;
$client = new GearmanClient();
$client->addServer();
$result = $client->doBackground("get_ipn", json_encode(array(
    'id' => $ipn->invoiceId
)));

//Respond with HTTP 200, so BitPay knows the IPN has been received correctly
//If BitPay receives <> HTTP 200, then BitPay will try to send the IPN again with increasing intervals for two more hours.
header("HTTP/1.1 200 OK");
?>