CSP: report-uri

The deprecated HTTP Content-Security-Policy (CSP) report-uri directive instructs the user agent to report attempts to violate the Content Security Policy. These violation reports consist of JSON documents sent via an HTTP POST request to the specified URI.

Content-Security-Policy: ...; report-uri https://endpoint.com; report-to groupname

The directive has no effect in and of itself, but only gains meaning in combination with other directives.

Syntax

Content-Security-Policy: report-uri <uri>;
Content-Security-Policy: report-uri <uri> <uri>;

<uri>

A URI where to POST the report to.

Examples

See Content-Security-Policy-Report-Only for more information and examples.

Content-Security-Policy: default-src https:; report-uri /csp-violation-report-endpoint/

/csp-violation-report-endpoint/ could for example run a PHP something like the following that logs the JSON detailing the violation and, if the violation is the first one added to the log file, sends an email to an administrator:

<?php

// Start configure
$log_file = dirname(__FILE__) . '/csp-violations.log';
$log_file_size_limit = 1000000; // bytes - once exceeded no further entries are added
$email_address = '[email protected]';
$email_subject = 'Content-Security-Policy violation';
// End configuration

$current_domain = preg_replace('/www\./i', '', $_SERVER['SERVER_NAME']);
$email_subject = $email_subject . ' on ' . $current_domain;

http_response_code(204); // HTTP 204 No Content

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

// We pretty print the JSON before adding it to the log file
if ($json_data = json_decode($json_data)) {
  $json_data = json_encode($json_data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);

  if (!file_exists($log_file)) {
    // Send an email
    $message = "The following Content-Security-Policy violation occurred on " .
      $current_domain . ":\n\n" .
      $json_data .
      "\n\nFurther CPS violations will be logged to the following log file, but no further email notifications will be sent until this log file is deleted:\n\n" .
      $log_file;
    mail($email_address, $email_subject, $message,
         'Content-Type: text/plain;charset=utf-8');
  } else if (filesize($log_file) > $log_file_size_limit) {
    exit(0);
  }

  file_put_contents($log_file, $json_data, FILE_APPEND | LOCK_EX);
}

?>

Specifications

Browser compatibilityUpdate compatibility data on GitHub

See also

• Content-Security-Policy
• Content-Security-Policy-Report-Only