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Enforce plugin rate limit when Stripe returns 429 errors #4327

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bc95775
Enforce plugin rate limit when Stripe has rate limited us
daledupreez May 16, 2025
67a1581
Keep basic history so we can see if this is recurring on a site
daledupreez May 16, 2025
ab72abc
Add explicit checks for 4xx and 5xx HTTP responses
daledupreez May 16, 2025
06b7e62
Separate rate checks from error handling
daledupreez May 16, 2025
88b405a
Merge branch 'develop' into try/detect-disconnected-stripe-via-401-er…
daledupreez May 16, 2025
2ec56a2
Changelog
daledupreez May 16, 2025
84e5af2
Improve name for duration constant
daledupreez May 16, 2025
4e638b8
Use multiline OR for $response checks
daledupreez May 16, 2025
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102 changes: 102 additions & 0 deletions includes/class-wc-stripe-api.php
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,28 @@ class WC_Stripe_API {
const ENDPOINT = 'https://api.stripe.com/v1/';
const STRIPE_API_VERSION = '2024-06-20';


/**
* Option key for cases where Stripe rate limits our live API calls.
*
* @var string
*/
public const LIVE_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY = 'wc_stripe_live_api_rate_limit';

/**
* Option key for cases where Stripe rate limits our test API calls.
*
* @var string
*/
public const TEST_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY = 'wc_stripe_test_api_rate_limit';

/**
* Duration we will use to disable Stripe API calls if we have been rate limited.
*
* @var int
*/
public const STRIPE_API_RATE_LIMIT_DURATION = 30;

/**
* Secret API Key.
*
Expand Down Expand Up @@ -231,6 +253,10 @@ public static function request( $request, $api = 'charges', $method = 'POST', $w
* @param string $api
*/
public static function retrieve( $api ) {
if ( self::is_stripe_api_rate_limited() ) {
return null;
}

WC_Stripe_Logger::log( "{$api}" );

$response = wp_safe_remote_get(
Expand All @@ -242,6 +268,8 @@ public static function retrieve( $api ) {
]
);

self::check_stripe_api_error_response( $response );

if ( is_wp_error( $response ) || empty( $response['body'] ) ) {
WC_Stripe_Logger::log( 'Error Response: ' . print_r( $response, true ) );
return new WP_Error( 'stripe_error', __( 'There was a problem connecting to the Stripe API endpoint.', 'woocommerce-gateway-stripe' ) );
Expand All @@ -250,6 +278,80 @@ public static function retrieve( $api ) {
return json_decode( $response['body'] );
}

/**
* Checks if the Stripe API for the current mode (i.e. test or live) is rate limited.
*
* @return bool True if the Stripe API is rate limited, false otherwise.
*/
public static function is_stripe_api_rate_limited() {
$rate_limit_option_key = WC_Stripe_Mode::is_test() ? self::TEST_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY : self::LIVE_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY;

$rate_limit_expiration = get_option( $rate_limit_option_key );
if ( ! $rate_limit_expiration ) {
return false;
}

$now = time();
if ( $now > $rate_limit_expiration ) {
delete_option( $rate_limit_option_key );
return false;
}

return true;
}

/**
* Helper function to check error responses from Stripe and ensure we prevent unnecessary API calls,
* primarily in cases where we have been rate limited or we don't have valid keys..
*
* @param array|WP_Error $response The response from the Stripe API.
* @return void
*/
protected static function check_stripe_api_error_response( $response ) {
// If we don't have an array for $response, return early, as we won't have an HTTP status code.
if ( ! is_array( $response ) ) {
return;
}

// We specifically want to check $response['response']['code']. If it's not present, return early.
if ( ! isset( $response['response'] ) || ! is_array( $response['response'] ) || ! isset( $response['response']['code'] ) ) {
return;
}

$status_code = $response['response']['code'];

if ( 429 === $status_code ) {
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Based on https://docs.stripe.com/rate-limits#rate-limited-requests, it is better to check for the header. It is possible that a 429 may not be related to rate-limiting. Both work fine, but checking the header would be more consistent.

// Stripe has rate limited us, so disable API calls for a period of time.
$is_test_mode = WC_Stripe_Mode::is_test();

$timestamp = time();
$rate_limit_option_key = $is_test_mode ? self::TEST_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY : self::LIVE_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY;
update_option( $rate_limit_option_key, $timestamp + self::STRIPE_API_RATE_LIMIT_DURATION );

$mode = $is_test_mode ? 'test' : 'LIVE';
$message = "Stripe {$mode} mode API has been rate limited, disabling API calls for " . self::STRIPE_API_RATE_LIMIT_DURATION . ' seconds.';

error_log( 'woocommerce-gateway-stripe: WARNING: ' . $message );
WC_Stripe_Logger::error( $message );

// Store history of rate limits so we can see how often they're occurring.
$history_option_key = $rate_limit_option_key . '_history';
$history = get_option( $history_option_key, [] );
if ( ! is_array( $history ) ) {
$history = [];
}
// Keep a maximum of 20 rate limit history entries.
$history = array_slice( $history, -19 );
$history[] = [
'timestamp' => $timestamp,
'datetime' => gmdate( 'Y-m-d H:i:s', $timestamp ) . ' UTC',
'duration' => self::STRIPE_API_RATE_LIMIT_DURATION,
];
// Note that we set autoload to false - we don't want this option to be autoloaded by default.
update_option( $history_option_key, $history, false );
}
}

/**
* Send the request to Stripe's API with level 3 data generated
* from the order. If the request fails due to an error related
Expand Down
215 changes: 215 additions & 0 deletions tests/phpunit/test-class-wc-stripe-api.php
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,17 @@ public function set_up() {
public function tear_down() {
WC_Stripe_Helper::delete_main_stripe_settings();
WC_Stripe_API::set_secret_key( null );

WC_Stripe_Logger::$logger = null;

if ( false !== has_filter( 'pre_http_request', [ $this, 'mock_429_response' ] ) ) {
remove_filter( 'pre_http_request', [ $this, 'mock_429_response' ] );
}

if ( false !== has_filter( 'pre_http_request', [ $this, 'throw_exception_on_http_request' ] ) ) {
remove_filter( 'pre_http_request', [ $this, 'throw_exception_on_http_request' ] );
}

parent::tear_down();
}

Expand Down Expand Up @@ -94,4 +105,208 @@ public function test_set_secret_key_for_mode_with_parameter() {
WC_Stripe_API::set_secret_key_for_mode( 'invalid' );
$this->assertEquals( self::LIVE_SECRET_KEY, WC_Stripe_API::get_secret_key() );
}

/**
* Provide test modes for test cases that test both test and live modes.
*
* @return array
*/
public function provide_test_modes() {
return [
'live mode' => [ false ],
'test mode' => [ true ],
];
}

/**
* Test WC_Stripe_API::retrieve() returns early when rate limit is active.
*
* @dataProvider provide_test_modes
* @param bool $is_test_mode Whether the test mode is true or false.
*/
public function test_retrieve_returns_early_when_rate_limit_is_active( $is_test_mode ) {
$settings = WC_Stripe_Helper::get_stripe_settings();
$settings['testmode'] = $is_test_mode ? 'yes' : 'no';
$settings['logging'] = 'yes';
WC_Stripe_Helper::update_main_stripe_settings( $settings );

// Add this filter after we update the settings, as that code can trigger HTTP requests.
add_filter( 'pre_http_request', [ $this, 'throw_exception_on_http_request' ] );

$mock_logger = $this->createStub( WC_Logger_Interface::class );

$mock_logger->expects( $this->never() )
->method( 'debug' );

$mock_logger->expects( $this->never() )
->method( 'error' );

$now = time();
$rate_limit_option_key = $is_test_mode ? WC_Stripe_API::TEST_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY : WC_Stripe_API::LIVE_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY;
update_option( $rate_limit_option_key, $now + 20 );

WC_Stripe_Logger::$logger = $mock_logger;

$result = WC_Stripe_API::retrieve( 'account' );

WC_Stripe_Logger::$logger = null;

$this->assertNull( $result );

remove_filter( 'pre_http_request', [ $this, 'throw_exception_on_http_request' ] );
}

/**
* Test WC_Stripe_API::is_stripe_api_rate_limited() returns false when no rate limit is active.
*
* @dataProvider provide_test_modes
* @param bool $is_test_mode Whether the test mode is true or false.
*/
public function test_rate_limit_check_returns_false_when_no_rate_limit_is_active( $is_test_mode ) {
$settings = WC_Stripe_Helper::get_stripe_settings();
$settings['testmode'] = $is_test_mode ? 'yes' : 'no';
WC_Stripe_Helper::update_main_stripe_settings( $settings );

$this->assertFalse( WC_Stripe_API::is_stripe_api_rate_limited() );
}

/**
* Test WC_Stripe_API::is_stripe_api_rate_limited() returns false and deletes the option after the rate limit expires.
*
* @dataProvider provide_test_modes
* @param bool $is_test_mode Whether the test mode is true or false.
*/
public function test_rate_limit_check_returns_false_and_deletes_option_after_rate_limit_expires( $is_test_mode ) {
$settings = WC_Stripe_Helper::get_stripe_settings();
$settings['testmode'] = $is_test_mode ? 'yes' : 'no';
WC_Stripe_Helper::update_main_stripe_settings( $settings );

$rate_limit_option_key = $is_test_mode ? WC_Stripe_API::TEST_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY : WC_Stripe_API::LIVE_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY;
update_option( $rate_limit_option_key, time() - 20 );

$this->assertFalse( WC_Stripe_API::is_stripe_api_rate_limited() );

$this->assertNull( get_option( $rate_limit_option_key, null ) );
}

/**
* Test WC_Stripe_API::retrieve() correctly triggers rate limiting when
* we receive a 429 response from the Stripe API.
*
* @dataProvider provide_test_modes
* @param bool $is_test_mode Whether the test mode is true or false.
*/
public function test_check_stripe_api_429_response_triggers_rate_limit( $is_test_mode ) {
$settings = WC_Stripe_Helper::get_stripe_settings();
$settings['testmode'] = $is_test_mode ? 'yes' : 'no';
$settings['logging'] = 'yes';
WC_Stripe_Helper::update_main_stripe_settings( $settings );

$rate_limit_option_key = $is_test_mode ? WC_Stripe_API::TEST_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY : WC_Stripe_API::LIVE_MODE_STRIPE_API_RATE_LIMIT_OPTION_KEY;
$history_option_key = $rate_limit_option_key . '_history';
update_option( $history_option_key, [], false );

$mock_logger = $this->createStub( WC_Logger_Interface::class );

$mock_logger->expects( $this->exactly( 2 ) )
->method( 'debug' )
->withConsecutive(
[ $this->get_expected_log_message( 'account' ) ],
[ $this->get_expected_log_prefix( 'Error Response: ' ) ],
);

$message_mode = $is_test_mode ? 'test' : 'LIVE';
$mock_logger->expects( $this->once() )
->method( 'error' )
->with(
"Stripe $message_mode mode API has been rate limited, disabling API calls for " . WC_Stripe_API::STRIPE_API_RATE_LIMIT_DURATION . ' seconds.'
);

// Mock 429 responses from the Stripe API.
add_filter( 'pre_http_request', [ $this, 'mock_429_response' ] );

WC_Stripe_Logger::$logger = $mock_logger;

$request_start_time = time();
$result = WC_Stripe_API::retrieve( 'account' );
$request_end_time = time();

// Unset the mock logger.
WC_Stripe_Logger::$logger = null;

$this->assertInstanceOf( WP_Error::class, $result );
$this->assertEquals( 'stripe_error', $result->get_error_code() );
$this->assertEquals( 'There was a problem connecting to the Stripe API endpoint.', $result->get_error_message() );

$rate_limit_option = get_option( $rate_limit_option_key );
$this->assertIsInt( $rate_limit_option );

$runtime_delta = max( $request_end_time - $request_start_time, 1 );
$this->assertEqualsWithDelta( $request_end_time + WC_Stripe_API::STRIPE_API_RATE_LIMIT_DURATION, $rate_limit_option, $runtime_delta );

$history = get_option( $history_option_key, null );
$this->assertIsArray( $history );
$this->assertCount( 1, $history );

$history_entry = $history[0];
$this->assertIsArray( $history_entry );
$this->assertArrayHasKey( 'timestamp', $history_entry );
$this->assertArrayHasKey( 'datetime', $history_entry );
$this->assertArrayHasKey( 'duration', $history_entry );

$expected_timestamp = $rate_limit_option - WC_Stripe_API::STRIPE_API_RATE_LIMIT_DURATION;
$this->assertEquals( $expected_timestamp, $history_entry['timestamp'] );
$this->assertEquals( gmdate( 'Y-m-d H:i:s', $expected_timestamp ) . ' UTC', $history_entry['datetime'] );
$this->assertEquals( WC_Stripe_API::STRIPE_API_RATE_LIMIT_DURATION, $history_entry['duration'] );

remove_filter( 'pre_http_request', [ $this, 'mock_429_response' ] );
}

/**
* Helper method to get the expected log message.
*
* @param string $message The message we expect to see in the log.
* @return string The expected log message.
*/
protected function get_expected_log_message( $message ) {
$expected_log_message = "\n" . '====Stripe Version: ' . WC_STRIPE_VERSION . '====' . "\n";
$expected_log_message .= '====Stripe Plugin API Version: ' . WC_Stripe_API::STRIPE_API_VERSION . '====' . "\n";
$expected_log_message .= '====Start Log====' . "\n" . $message . "\n" . '====End Log====' . "\n\n";

return $expected_log_message;
}

/**
* Helper method to get the expected log message prefix.
*
* @param string $message The message prefix we expect to see in the log.
* @return string The expected log message prefix.
*/
protected function get_expected_log_prefix( $message ) {
$expected_log_prefix = "\n" . '====Stripe Version: ' . WC_STRIPE_VERSION . '====' . "\n";
$expected_log_prefix .= '====Stripe Plugin API Version: ' . WC_Stripe_API::STRIPE_API_VERSION . '====' . "\n";
$expected_log_prefix .= '====Start Log====' . "\n" . $message;

return $this->stringStartsWith( $expected_log_prefix );
}

/**
* Helper method to mock an HTTP 429 response from the Stripe API.
*/
public function mock_429_response( $preempt ) {
return [
'response' => [
'code' => 429,
'message' => 'Too many requests',
],
'body' => '',
];
}

/**
* Helper method to throw an when triggered.
*/
public function throw_exception_on_http_request( $preempt ) {
throw new Exception( 'HTTP request should not be triggered' );
}
}
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