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lohanidamodarlohanidamodar
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Merge pull request #17 from utopia-php/feat-stripe-webhook-validator
Stripe webhook validator and test
2 parents b674a1e + 6e35377 commit 3f09fe6

4 files changed

Lines changed: 184 additions & 3 deletions

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‎.github/workflows/tests.yml‎

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@@ -27,4 +27,5 @@ jobs:
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- name: Run tests
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run: |
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export STRIPE_SECRET=${{ secrets.STRIPE_SECRET }}
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export STRIPE_WEBHOOK_SECRET=${{ secrets.STRIPE_WEBHOOK_SECRET }}
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composer test

‎src/Pay/Validator/Stripe/Webhook.php‎

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<?php
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namespace Utopia\Pay\Validator\Stripe;
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// header
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// t=1723597289,v1=f53b5765cc9847786d33f8f96d9e22c0d08967271a734b1a69327e22ecf1bc73,v0=353c23cbcfc17f983e3089a339d2004174ee472df39e61d7e52805008ffad044
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// secret
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// whsec_2FMR5OjJa6Czcj3G07HvMGjLsw8uw3dQ
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class Webhook
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{
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public const DEFAULT_TOLERANCE = 300;
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public const EXPECTED_SCHEME = 'v1';
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private static $isHashEqualsAvailable = null;
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/**
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* Verifies the signature header sent by Stripe. Throws an
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* Exception\SignatureVerificationException exception if the verification fails for
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* any reason.
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*
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* @param string $payload the payload sent by Stripe
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* @param string $header the contents of the signature header sent by
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* Stripe
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* @param string $secret secret used to generate the signature
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* @param int $tolerance maximum difference allowed between the header's
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* timestamp and the current time
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* @return bool
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*/
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public function isValid($payload, $header, $secret, $tolerance = null)
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{
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// Extract timestamp and signatures from header
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$timestamp = $this->getTimestamp($header);
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$signatures = $this->getSignatures($header, self::EXPECTED_SCHEME);
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if (-1 === $timestamp) {
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return false;
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}
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if (empty($signatures)) {
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return false;
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}
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// Check if expected signature is found in list of signatures from
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// header
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$signedPayload = "{$timestamp}.{$payload}";
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$expectedSignature = $this->computeSignature($signedPayload, $secret);
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$signatureFound = false;
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foreach ($signatures as $signature) {
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if ($this->secureCompare($expectedSignature, $signature)) {
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$signatureFound = true;
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break;
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}
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}
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if (! $signatureFound) {
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return false;
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}
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// Check if timestamp is within tolerance
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if (($tolerance > 0) && (\abs(\time() - $timestamp) > $tolerance)) {
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return false;
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}
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return true;
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}
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public function secureCompare($a, $b)
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{
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if (null === self::$isHashEqualsAvailable) {
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self::$isHashEqualsAvailable = \function_exists('hash_equals');
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}
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if (self::$isHashEqualsAvailable) {
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return \hash_equals($a, $b);
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}
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if (\strlen($a) !== \strlen($b)) {
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return false;
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}
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$result = 0;
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for ($i = 0; $i < \strlen($a); $i++) {
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$result |= \ord($a[$i]) ^ \ord($b[$i]);
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}
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return 0 === $result;
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}
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/**
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* Extracts the timestamp in a signature header.
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*
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* @param string $header the signature header
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* @return int the timestamp contained in the header, or -1 if no valid
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* timestamp is found
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*/
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private function getTimestamp($header)
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{
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$items = \explode(',', $header);
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foreach ($items as $item) {
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$itemParts = \explode('=', $item, 2);
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if ('t' === $itemParts[0]) {
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if (! \is_numeric($itemParts[1])) {
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return -1;
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}
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return (int) ($itemParts[1]);
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}
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}
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return -1;
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}
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/**
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* Extracts the signatures matching a given scheme in a signature header.
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*
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* @param string $header the signature header
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* @param string $scheme the signature scheme to look for
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* @return array the list of signatures matching the provided scheme
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*/
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private function getSignatures($header, $scheme)
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{
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$signatures = [];
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$items = \explode(',', $header);
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foreach ($items as $item) {
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$itemParts = \explode('=', $item, 2);
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if (\trim($itemParts[0]) === $scheme) {
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$signatures[] = $itemParts[1];
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}
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}
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return $signatures;
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}
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/**
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* Computes the signature for a given payload and secret.
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*
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* The current scheme used by Stripe ("v1") is HMAC/SHA-256.
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*
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* @param string $payload the payload to sign
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* @param string $secret the secret used to generate the signature
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* @return string the signature as a string
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*/
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private function computeSignature($payload, $secret)
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{
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return \hash_hmac('sha256', $payload, $secret);
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}
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}

‎tests/Pay/Adapter/StripeTest.php‎

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@@ -83,8 +83,8 @@ public function testListCustomers(array $data): void
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$this->assertNotEmpty($response['data']);
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$customers = $response['data'];
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$this->assertNotEmpty($customers[0]['id']);
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$this->assertEquals($customers[0]['name'], 'Test Updated');
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$this->assertEquals($customers[0]['email'], 'testcustomerupdated@email.com');
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$this->assertNotEmpty($customers[0]['name']);
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$this->assertNotEmpty($customers[0]['email']);
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}
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/**
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$setupIntents = $this->stripe->listFuturePayments($customerId);
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$this->assertNotEmpty($setupIntents);
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$this->assertEquals($setupIntentId, $setupIntents[0]['id']);
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$this->assertNotEmpty($setupIntents[0]['id']);
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}
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/**

‎tests/Pay/Validator/Stripe/WebhookTest.php‎

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<?php
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namespace Utopia\Tests;
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use PHPUnit\Framework\TestCase;
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use Utopia\Pay\Validator\Stripe\Webhook;
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class WebhookTest extends TestCase
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{
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public function testValid()
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{
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$header = 't=1723597289,v1=ca18f2c5b48c347b26f2d862f29d93dc1c9c6b319ba2cd934db54333acef1492';
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$secret = getenv('STRIPE_WEBHOOK_SECRET');
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$validator = new Webhook();
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// test valid (Tolerance set to high)
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$isValid = $validator->isValid('{"id": "pi_abcdefg"}', $header, $secret, PHP_INT_MAX);
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$this->assertTrue($isValid);
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// Test time tolerance low
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$isValid = $validator->isValid('{"id": "pi_abcdefg"}', $header, $secret, 10);
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$this->assertFalse($isValid);
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// payload doesn't match
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$isValid = $validator->isValid('{"id": "pi_abcdef"}', $header, $secret, PHP_INT_MAX);
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$this->assertFalse($isValid);
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// Secret doesn't match
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$isValid = $validator->isValid('{"id": "pi_abcdefg"}', $header, $secret.'ef', PHP_INT_MAX);
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$this->assertFalse($isValid);
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}
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}

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