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<?php
namespace WPForms\Forms;
use WPForms\Helpers\Crypto;
/**
* Class Token.
*
* This token class generates tokens that are used in our Anti-Spam checking mechanism.
*
* @since 1.6.2
*/
class Token {
/**
* Initialise the actions for the Anti-spam.
*
* @since 1.6.2
*/
public function init() {
$this->hooks();
}
/**
* Register hooks.
*
* @since 1.6.2
*/
public function hooks() {
add_filter( 'wpforms_frontend_form_atts', [ $this, 'add_token_to_form_atts' ], 10, 2 );
add_filter( 'wpforms_frontend_strings', [ $this, 'add_frontend_strings' ] );
add_action( 'wp_ajax_nopriv_wpforms_get_token', [ $this, 'ajax_get_token' ] );
add_action( 'wp_ajax_wpforms_get_token', [ $this, 'ajax_get_token' ] );
}
/**
* Return a valid token.
*
* @since 1.6.2
* @since 1.7.1 Added the $form_data argument.
*
* @param mixed $current True to use current time, otherwise a timestamp string.
* @param array $form_data Form data and settings.
*
* @return string Token.
*/
public function get( $current = true, $form_data = [] ) {
// If $current was not passed, or it is true, we use the current timestamp.
// If $current was passed in as a string, we'll use that passed in timestamp.
if ( $current !== true ) {
$time = $current;
} else {
$time = time();
}
// Format the timestamp to be less exact, as we want to deal in days.
// June 19th, 2020 would get formatted as: 1906202017125.
// Day of the month, month number, year, day number of the year, week number of the year.
$token_data = gmdate( 'dmYzW', $time );
if ( ! empty( $form_data['id'] ) ) {
$token_data .= "::{$form_data['id']}";
}
// Combine our token date and our token salt, and md5 it.
return md5( $token_data . Crypto::get_secret_key() ); // NOSONAR.
}
/**
* Generate the array of valid tokens to check for. These include two days
* before the current date to account for long cache times.
*
* These two filters are available if a user wants to extend the times.
* 'wpforms_form_token_check_before_today'
* 'wpforms_form_token_check_after_today'
*
* @since 1.6.2
* @since 1.7.1 Added the $form_data argument.
*
* @param array $form_data Form data and settings.
*
* @return array Array of all valid tokens to check against.
*/
public function get_valid_tokens( $form_data = [] ) {
$current_date = time();
$valid_token_times_before = [];
$days_in_5_years = 5 * 365;
// Create an array of 5 years worth of days.
for ( $i = 1; $i <= $days_in_5_years; $i++ ) {
$valid_token_times_before[] = $i * DAY_IN_SECONDS;
}
// Create our array of times to check before today. A user with a longer
// cache time can extend this. A user with a shorter cache time can remove times.
$valid_token_times_before = apply_filters(
'wpforms_form_token_check_before_today',
$valid_token_times_before
);
// Mostly to catch edge cases like the form page loading and submitting on two different days.
// This probably won't be filtered by users too much, but they could extend it.
$valid_token_times_after = apply_filters(
'wpforms_form_token_check_after_today',
[
( 45 * MINUTE_IN_SECONDS ), // Add in 45 minutes past today to catch some midnight edge cases.
]
);
// Built up our valid tokens.
$valid_tokens = [];
// Add in all the previous times we check.
foreach ( $valid_token_times_before as $time ) {
$valid_tokens[] = $this->get( $current_date - $time, $form_data );
}
// Add in our current date.
$valid_tokens[] = $this->get( $current_date, $form_data );
// Add in the times after our check.
foreach ( $valid_token_times_after as $time ) {
$valid_tokens[] = $this->get( $current_date + $time, $form_data );
}
return $valid_tokens;
}
/**
* Check if the given token is valid or not.
*
* Tokens are valid for some period of time (see wpforms_token_validity_in_hours
* and wpforms_token_validity_in_days to extend the validation period).
* By default tokens are valid for day.
*
* @since 1.6.2
* @since 1.7.1 Added the $form_data argument.
*
* @param string $token Token to validate.
* @param array $form_data Form data and settings.
*
* @return bool Whether the token is valid or not.
*/
public function verify( string $token, array $form_data = [] ): bool {
// Check to see if our token is inside the valid tokens.
return in_array( $token, $this->get_valid_tokens( $form_data ), true );
}
/**
* Add the token to the form attributes.
*
* @since 1.6.2
* @since 1.7.1 Added the $form_data argument.
*
* @param array $attrs Form attributes.
* @param array $form_data Form data and settings.
*
* @return array Form attributes.
*/
public function add_token_to_form_atts( array $attrs, array $form_data ) {
$attrs['atts']['data-token'] = $this->get( true, $form_data );
$attrs['atts']['data-token-time'] = time();
return $attrs;
}
/**
* Get the signed render time token.
*
* The token carries the server-side render timestamp along with its signature,
* so the elapsed submission time cannot be forged on the client.
*
* @since 2.0.2
*
* @param array $form_data Form data and settings.
*
* @return string Token in the `{time}.{signature}` format.
*/
public function get_time_token( array $form_data ): string {
$time = time();
$signature = $this->sign_time( $time, absint( $form_data['id'] ?? 0 ) );
return "{$time}.{$signature}";
}
/**
* Verify the signed render time token and return the render timestamp it carries.
*
* @since 2.0.2
*
* @param string $token Token to verify.
* @param int $form_id Form ID the token has to be bound to.
*
* The token has no maximum age, and that is a deliberate limit on what this check can do. A page
* cache serves the markup it stored, so the render time inside it is the cache fill time rather
* than the moment this visitor received the form, and the minimum time to submit check therefore
* has no effect on a cached page older than its own duration. Expiring the token instead would
* reject legitimate entries it cannot tell apart: the server sees the same old signed timestamp
* whether the visitor has been reading the page or the markup came out of a cache. Telling those
* two apart needs proof that the same client has been present since the render, which a single
* stateless timestamp cannot carry.
*
* @return int Render timestamp, or 0 when the token carries no usable one: missing, malformed,
* wrongly signed, or dated ahead of the server clock.
*/
public function verify_time_token( string $token, int $form_id ): int {
$parts = explode( '.', $token );
if ( count( $parts ) !== 2 ) {
return 0;
}
[ $time, $signature ] = $parts;
if ( ! ctype_digit( $time ) ) {
return 0;
}
$render_time = (int) $time;
if ( ! hash_equals( $this->sign_time( $render_time, $form_id ), $signature ) ) {
return 0;
}
// Only this site signs these tokens and it only ever signs the present, so a render time
// ahead of the clock means the clock moved backwards. Report no render time rather than let
// the caller subtract into a negative elapsed time it cannot tell apart from a fast submission.
if ( $render_time > time() ) {
return 0;
}
return $render_time;
}
/**
* Sign the render timestamp for the given form.
*
* An HMAC is used rather than `Crypto::encrypt()`: it is deterministic, short enough for an HTML
* attribute, and can be compared in constant time.
*
* @since 2.0.2
*
* @param int $time Render timestamp.
* @param int $form_id Form ID.
*
* @return string Signature.
*/
private function sign_time( int $time, int $form_id ): string {
return hash_hmac( 'sha256', "{$time}|{$form_id}", Crypto::get_secret_key() );
}
/**
* Validate Anti-spam if enabled.
*
* @since 1.6.2
*
* @param array $form_data Form data.
* @param array $fields Fields.
* @param array $entry Form entry.
*
* @return bool|string True or a string with the error.
*/
public function validate( array $form_data, array $fields, array $entry ) {
// Bail out if we don't have the antispam setting.
if ( empty( $form_data['settings']['antispam'] ) ) {
return true;
}
// Bail out if the antispam setting isn't enabled.
if ( $form_data['settings']['antispam'] !== '1' ) {
return true;
}
$is_valid_token = isset( $entry['token'] ) && $this->verify( (string) $entry['token'], $form_data );
if ( $this->process_antispam_filter_wrapper( $is_valid_token, $fields, $entry, $form_data ) ) {
return true;
}
// Prepare the log data.
$form_title = $form_data['settings']['form_title'] ?? '';
$form_id = $form_data['id'] ?? 'unknown';
if ( $is_valid_token ) {
// Token is OK, but antispam filter is not passed.
$log_message = 'Filter is not passed';
$error_message = $this->get_antispam_filter_message();
} else {
// Invalid token.
$log_message = 'Token is invalid';
$error_message = $this->get_invalid_token_message();
}
wpforms_log(
'Antispam: ' . $log_message,
[
'message' => $error_message,
'referer' => esc_url_raw( (string) wp_get_referer() ),
'form' => ! empty( $form_title ) ? $form_title . ' (ID: ' . $form_id . ')' : 'ID: ' . $form_id,
'token' => $entry['token'] ?? '',
'user_ip' => wpforms_get_ip(),
'entry_data' => ! wpforms_setting( 'gdpr' ) ? $entry : 'Not logged',
],
[
'type' => [ 'spam', 'error' ],
'form_id' => $form_data['id'],
'force' => true,
]
);
return $error_message;
}
/**
* Helper to run our filter on all the responses for the antispam checks.
*
* @since 1.6.2
*
* @param bool $is_valid_not_spam Is valid entry or not.
* @param array $fields Form Fields.
* @param array $entry Form entry.
* @param array $form_data Form Data.
*
* @return bool Is valid or not.
*/
public function process_antispam_filter_wrapper( bool $is_valid_not_spam, array $fields, array $entry, array $form_data ): bool {
/**
* Allows developers to filter the antispam check result.
*
* @since 1.6.2
*
* @param bool $is_valid_not_spam True if entry valid, false otherwise.
* @param array $fields Fields data.
* @param array $entry Entry data.
* @param array $form_data Form data.
*/
return (bool) apply_filters( 'wpforms_process_antispam', $is_valid_not_spam, $fields, $entry, $form_data ); // phpcs:ignore WPForms.PHP.ValidateHooks.InvalidHookName
}
/**
* Helper to get the invalid token message.
*
* @since 1.6.2.1
*
* @return string Invalid token message.
*/
private function get_invalid_token_message(): string {
return $this->get_error_message( esc_html__( 'Antispam token is invalid.', 'wpforms-lite' ) );
}
/**
* Helper to get the antispam filter error message.
*
* @since 1.8.9
*
* @return string Missing token message.
*/
private function get_antispam_filter_message(): string {
return $this->get_error_message( esc_html__( 'Antispam filter did not allow your data to pass through.', 'wpforms-lite' ) );
}
/**
* Get error message depends on user.
*
* @since 1.6.4.1
*
* @param string $text Message text.
*
* @return string
*/
private function get_error_message( string $text ): string {
$text .= ' ' . esc_html__( 'Please reload the page and try submitting the form again.', 'wpforms-lite' );
return wpforms_current_user_can() ? $text . $this->maybe_get_support_text() : $text;
}
/**
* If a user is a super admin, add a support link to the message.
*
* @since 1.6.2.1
*
* @return string Support text if super admin, empty string if not.
*/
private function maybe_get_support_text(): string {
// If a user isn't a super admin, don't return any text.
if ( ! is_super_admin() ) {
return '';
}
// If the user is an admin, return text with a link to support.
// We add a space here to separate the sentences, but outside the localized text to avoid it being removed.
return ' ' . sprintf(
/* translators: placeholders are links. */
esc_html__( 'Please check out our %1$stroubleshooting guide%2$s for details on resolving this issue.', 'wpforms-lite' ),
'<a href="https://wpforms.com/docs/getting-support-wpforms/">',
'</a>'
);
}
/**
* Add token related strings to the frontend.
*
* @since 1.8.8
*
* @param array|mixed $strings Frontend strings.
*
* @return array Frontend strings.
*/
public function add_frontend_strings( $strings ): array {
$strings = (array) $strings;
$strings['error_updating_token'] = esc_html__(
'Error updating token. Please try again or contact support if the issue persists.',
'wpforms-lite'
);
$strings['network_error'] = esc_html__(
'Network error or server is unreachable. Check your connection or try again later.',
'wpforms-lite'
);
// Default token lifetime is 24 hours in seconds.
$token_lifetime = DAY_IN_SECONDS;
/**
* Filter token cache lifetime in seconds.
*
* @since 1.8.8
*
* @param integer $token_lifetime Token lifetime in seconds.
*/
$strings['token_cache_lifetime'] = apply_filters( 'wpforms_forms_token_cache_lifetime', $token_lifetime );
return $strings;
}
/**
* Update token via ajax handler.
*
* @since 1.8.8
* @since 2.0.2 Added the signed render time token to the response, and the form ID validation.
*/
public function ajax_get_token() {
$form_id = filter_input( INPUT_POST, 'formId', FILTER_VALIDATE_INT );
// Both tokens are bound to the form, so neither could ever be verified without a valid ID.
if ( ! is_int( $form_id ) || $form_id < 1 ) {
wp_send_json_error();
}
$form_data = [ 'id' => $form_id ];
$response = [
'token' => $this->get( true, $form_data ),
'time_token' => $this->get_time_token( $form_data ),
];
wp_send_json_success( $response );
}
}