mirror of
https://we.phorge.it/source/phorge.git
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c887871d30
Summary: This is still too rough to enable by default. We can turn it on for `secure.phabricator.com` and tweak it a bit first, and then release it in general with higher defaults and more sensible behavior in edge cases. Test Plan: Loaded some pages. Reviewers: btrahan, spicyj Reviewed By: spicyj Subscribers: epriestley Differential Revision: https://secure.phabricator.com/D8736
780 lines
22 KiB
PHP
780 lines
22 KiB
PHP
<?php
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/**
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* Handle request startup, before loading the environment or libraries. This
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* class bootstraps the request state up to the point where we can enter
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* Phabricator code.
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*
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* NOTE: This class MUST NOT have any dependencies. It runs before libraries
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* load.
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*
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* Rate Limiting
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* =============
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*
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* Phabricator limits the rate at which clients can request pages, and issues
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* HTTP 429 "Too Many Requests" responses if clients request too many pages too
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* quickly. Although this is not a complete defense against high-volume attacks,
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* it can protect an install against aggressive crawlers, security scanners,
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* and some types of malicious activity.
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*
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* To perform rate limiting, each page increments a score counter for the
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* requesting user's IP. The page can give the IP more points for an expensive
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* request, or fewer for an authetnicated request.
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*
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* Score counters are kept in buckets, and writes move to a new bucket every
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* minute. After a few minutes (defined by @{method:getRateLimitBucketCount}),
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* the oldest bucket is discarded. This provides a simple mechanism for keeping
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* track of scores without needing to store, access, or read very much data.
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*
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* Users are allowed to accumulate up to 1000 points per minute, averaged across
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* all of the tracked buckets.
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*
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* @task info Accessing Request Information
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* @task hook Startup Hooks
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* @task apocalypse In Case Of Apocalypse
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* @task validation Validation
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* @task ratelimit Rate Limiting
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*/
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final class PhabricatorStartup {
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private static $startTime;
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private static $globals = array();
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private static $capturingOutput;
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private static $rawInput;
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// TODO: For now, disable rate limiting entirely by default. We need to
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// iterate on it a bit for Conduit, some of the specific score levels, and
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// to deal with NAT'd offices.
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private static $maximumRate = 0;
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/* -( Accessing Request Information )-------------------------------------- */
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/**
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* @task info
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*/
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public static function getStartTime() {
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return self::$startTime;
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}
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/**
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* @task info
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*/
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public static function getMicrosecondsSinceStart() {
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return (int)(1000000 * (microtime(true) - self::getStartTime()));
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}
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/**
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* @task info
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*/
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public static function setGlobal($key, $value) {
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self::validateGlobal($key);
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self::$globals[$key] = $value;
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}
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/**
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* @task info
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*/
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public static function getGlobal($key, $default = null) {
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self::validateGlobal($key);
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if (!array_key_exists($key, self::$globals)) {
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return $default;
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}
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return self::$globals[$key];
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}
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/**
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* @task info
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*/
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public static function getRawInput() {
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return self::$rawInput;
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}
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/* -( Startup Hooks )------------------------------------------------------ */
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/**
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* @task hook
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*/
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public static function didStartup() {
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self::$startTime = microtime(true);
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self::$globals = array();
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static $registered;
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if (!$registered) {
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// NOTE: This protects us against multiple calls to didStartup() in the
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// same request, but also against repeated requests to the same
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// interpreter state, which we may implement in the future.
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register_shutdown_function(array(__CLASS__, 'didShutdown'));
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$registered = true;
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}
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self::setupPHP();
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self::verifyPHP();
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if (isset($_SERVER['REMOTE_ADDR'])) {
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self::rateLimitRequest($_SERVER['REMOTE_ADDR']);
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}
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self::normalizeInput();
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self::verifyRewriteRules();
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self::detectPostMaxSizeTriggered();
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self::beginOutputCapture();
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self::$rawInput = (string)file_get_contents('php://input');
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}
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/**
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* @task hook
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*/
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public static function didShutdown() {
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$event = error_get_last();
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if (!$event) {
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return;
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}
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switch ($event['type']) {
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case E_ERROR:
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case E_PARSE:
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case E_COMPILE_ERROR:
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break;
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default:
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return;
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}
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$msg = ">>> UNRECOVERABLE FATAL ERROR <<<\n\n";
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if ($event) {
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// Even though we should be emitting this as text-plain, escape things
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// just to be sure since we can't really be sure what the program state
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// is when we get here.
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$msg .= htmlspecialchars(
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$event['message']."\n\n".$event['file'].':'.$event['line'],
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ENT_QUOTES,
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'UTF-8');
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}
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// flip dem tables
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$msg .= "\n\n\n";
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$msg .= "\xe2\x94\xbb\xe2\x94\x81\xe2\x94\xbb\x20\xef\xb8\xb5\x20\xc2\xaf".
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"\x5c\x5f\x28\xe3\x83\x84\x29\x5f\x2f\xc2\xaf\x20\xef\xb8\xb5\x20".
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"\xe2\x94\xbb\xe2\x94\x81\xe2\x94\xbb";
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self::didFatal($msg);
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}
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public static function loadCoreLibraries() {
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$phabricator_root = dirname(dirname(__FILE__));
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$libraries_root = dirname($phabricator_root);
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$root = null;
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if (!empty($_SERVER['PHUTIL_LIBRARY_ROOT'])) {
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$root = $_SERVER['PHUTIL_LIBRARY_ROOT'];
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}
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ini_set(
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'include_path',
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$libraries_root.PATH_SEPARATOR.ini_get('include_path'));
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@include_once $root.'libphutil/src/__phutil_library_init__.php';
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if (!@constant('__LIBPHUTIL__')) {
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self::didFatal(
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"Unable to load libphutil. Put libphutil/ next to phabricator/, or ".
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"update your PHP 'include_path' to include the parent directory of ".
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"libphutil/.");
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}
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phutil_load_library('arcanist/src');
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// Load Phabricator itself using the absolute path, so we never end up doing
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// anything surprising (loading index.php and libraries from different
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// directories).
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phutil_load_library($phabricator_root.'/src');
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}
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/* -( Output Capture )----------------------------------------------------- */
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public static function beginOutputCapture() {
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if (self::$capturingOutput) {
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self::didFatal("Already capturing output!");
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}
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self::$capturingOutput = true;
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ob_start();
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}
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public static function endOutputCapture() {
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if (!self::$capturingOutput) {
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return null;
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}
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self::$capturingOutput = false;
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return ob_get_clean();
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}
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/* -( In Case of Apocalypse )---------------------------------------------- */
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/**
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* Fatal the request completely in response to an exception, sending a plain
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* text message to the client. Calls @{method:didFatal} internally.
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*
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* @param string Brief description of the exception context, like
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* `"Rendering Exception"`.
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* @param Exception The exception itself.
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* @param bool True if it's okay to show the exception's stack trace
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* to the user. The trace will always be logged.
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* @return exit This method **does not return**.
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*
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* @task apocalypse
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*/
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public static function didEncounterFatalException(
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$note,
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Exception $ex,
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$show_trace) {
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$message = '['.$note.'/'.get_class($ex).'] '.$ex->getMessage();
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$full_message = $message;
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$full_message .= "\n\n";
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$full_message .= $ex->getTraceAsString();
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if ($show_trace) {
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$message = $full_message;
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}
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self::didFatal($message, $full_message);
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}
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/**
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* Fatal the request completely, sending a plain text message to the client.
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*
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* @param string Plain text message to send to the client.
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* @param string Plain text message to send to the error log. If not
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* provided, the client message is used. You can pass a more
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* detailed message here (e.g., with stack traces) to avoid
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* showing it to users.
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* @return exit This method **does not return**.
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*
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* @task apocalypse
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*/
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public static function didFatal($message, $log_message = null) {
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if ($log_message === null) {
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$log_message = $message;
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}
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self::endOutputCapture();
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$access_log = self::getGlobal('log.access');
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if ($access_log) {
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// We may end up here before the access log is initialized, e.g. from
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// verifyPHP().
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$access_log->setData(
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array(
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'c' => 500,
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));
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$access_log->write();
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}
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header(
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'Content-Type: text/plain; charset=utf-8',
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$replace = true,
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$http_error = 500);
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error_log($log_message);
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echo $message;
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exit(1);
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}
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/* -( Validation )--------------------------------------------------------- */
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/**
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* @task validation
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*/
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private static function setupPHP() {
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error_reporting(E_ALL | E_STRICT);
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ini_set('memory_limit', -1);
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// If we have libxml, disable the incredibly dangerous entity loader.
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if (function_exists('libxml_disable_entity_loader')) {
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libxml_disable_entity_loader(true);
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}
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}
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/**
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* @task validation
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*/
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private static function normalizeInput() {
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// Replace superglobals with unfiltered versions, disrespect php.ini (we
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// filter ourselves)
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$filter = array(INPUT_GET, INPUT_POST,
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INPUT_SERVER, INPUT_ENV, INPUT_COOKIE);
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foreach ($filter as $type) {
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$filtered = filter_input_array($type, FILTER_UNSAFE_RAW);
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if (!is_array($filtered)) {
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continue;
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}
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switch ($type) {
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case INPUT_SERVER:
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$_SERVER = array_merge($_SERVER, $filtered);
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break;
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case INPUT_GET:
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$_GET = array_merge($_GET, $filtered);
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break;
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case INPUT_COOKIE:
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$_COOKIE = array_merge($_COOKIE, $filtered);
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break;
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case INPUT_POST:
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$_POST = array_merge($_POST, $filtered);
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break;
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case INPUT_ENV;
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$_ENV = array_merge($_ENV, $filtered);
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break;
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}
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}
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// rebuild $_REQUEST, respecting order declared in ini files
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$order = ini_get('request_order');
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if (!$order) {
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$order = ini_get('variables_order');
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}
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if (!$order) {
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// $_REQUEST will be empty, leave it alone
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return;
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}
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$_REQUEST = array();
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for ($i = 0; $i < strlen($order); $i++) {
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switch ($order[$i]) {
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case 'G':
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$_REQUEST = array_merge($_REQUEST, $_GET);
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break;
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case 'P':
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$_REQUEST = array_merge($_REQUEST, $_POST);
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break;
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case 'C':
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$_REQUEST = array_merge($_REQUEST, $_COOKIE);
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break;
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default:
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// $_ENV and $_SERVER never go into $_REQUEST
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break;
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}
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}
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}
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/**
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* @task validation
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*/
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private static function verifyPHP() {
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$required_version = '5.2.3';
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if (version_compare(PHP_VERSION, $required_version) < 0) {
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self::didFatal(
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"You are running PHP version '".PHP_VERSION."', which is older than ".
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"the minimum version, '{$required_version}'. Update to at least ".
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"'{$required_version}'.");
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}
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if (get_magic_quotes_gpc()) {
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self::didFatal(
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"Your server is configured with PHP 'magic_quotes_gpc' enabled. This ".
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"feature is 'highly discouraged' by PHP's developers and you must ".
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"disable it to run Phabricator. Consult the PHP manual for ".
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"instructions.");
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}
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if (extension_loaded('apc')) {
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$apc_version = phpversion('apc');
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$known_bad = array(
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'3.1.14' => true,
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'3.1.15' => true,
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'3.1.15-dev' => true,
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);
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if (isset($known_bad[$apc_version])) {
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self::didFatal(
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"You have APC {$apc_version} installed. This version of APC is ".
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"known to be bad, and does not work with Phabricator (it will ".
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"cause Phabricator to fatal unrecoverably with nonsense errors). ".
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"Downgrade to version 3.1.13.");
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}
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}
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}
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/**
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* @task validation
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*/
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private static function verifyRewriteRules() {
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if (isset($_REQUEST['__path__']) && strlen($_REQUEST['__path__'])) {
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return;
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}
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if (php_sapi_name() == 'cli-server') {
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// Compatibility with PHP 5.4+ built-in web server.
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$url = parse_url($_SERVER['REQUEST_URI']);
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$_REQUEST['__path__'] = $url['path'];
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return;
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}
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if (!isset($_REQUEST['__path__'])) {
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self::didFatal(
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"Request parameter '__path__' is not set. Your rewrite rules ".
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"are not configured correctly.");
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}
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if (!strlen($_REQUEST['__path__'])) {
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self::didFatal(
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"Request parameter '__path__' is set, but empty. Your rewrite rules ".
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"are not configured correctly. The '__path__' should always ".
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"begin with a '/'.");
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}
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}
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/**
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* @task validation
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*/
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private static function validateGlobal($key) {
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static $globals = array(
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'log.access' => true,
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'csrf.salt' => true,
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);
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if (empty($globals[$key])) {
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throw new Exception("Access to unknown startup global '{$key}'!");
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}
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}
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/**
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* Detect if this request has had its POST data stripped by exceeding the
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* 'post_max_size' PHP configuration limit.
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*
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* PHP has a setting called 'post_max_size'. If a POST request arrives with
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* a body larger than the limit, PHP doesn't generate $_POST but processes
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* the request anyway, and provides no formal way to detect that this
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* happened.
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*
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* We can still read the entire body out of `php://input`. However according
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* to the documentation the stream isn't available for "multipart/form-data"
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* (on nginx + php-fpm it appears that it is available, though, at least) so
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* any attempt to generate $_POST would be fragile.
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*
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* @task validation
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*/
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private static function detectPostMaxSizeTriggered() {
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// If this wasn't a POST, we're fine.
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if ($_SERVER['REQUEST_METHOD'] != 'POST') {
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return;
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}
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// If there's POST data, clearly we're in good shape.
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if ($_POST) {
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return;
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}
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// For HTML5 drag-and-drop file uploads, Safari submits the data as
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// "application/x-www-form-urlencoded". For most files this generates
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// something in POST because most files decode to some nonempty (albeit
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// meaningless) value. However, some files (particularly small images)
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// don't decode to anything. If we know this is a drag-and-drop upload,
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// we can skip this check.
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if (isset($_REQUEST['__upload__'])) {
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return;
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}
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// PHP generates $_POST only for two content types. This routing happens
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// in `main/php_content_types.c` in PHP. Normally, all forms use one of
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// these content types, but some requests may not -- for example, Firefox
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// submits files sent over HTML5 XMLHTTPRequest APIs with the Content-Type
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// of the file itself. If we don't have a recognized content type, we
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// don't need $_POST.
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//
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// NOTE: We use strncmp() because the actual content type may be something
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// like "multipart/form-data; boundary=...".
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//
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// NOTE: Chrome sometimes omits this header, see some discussion in T1762
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// and http://code.google.com/p/chromium/issues/detail?id=6800
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$content_type = isset($_SERVER['CONTENT_TYPE'])
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? $_SERVER['CONTENT_TYPE']
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: '';
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$parsed_types = array(
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'application/x-www-form-urlencoded',
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'multipart/form-data',
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);
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$is_parsed_type = false;
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foreach ($parsed_types as $parsed_type) {
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if (strncmp($content_type, $parsed_type, strlen($parsed_type)) === 0) {
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$is_parsed_type = true;
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break;
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}
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}
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if (!$is_parsed_type) {
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return;
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}
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// Check for 'Content-Length'. If there's no data, we don't expect $_POST
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// to exist.
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$length = (int)$_SERVER['CONTENT_LENGTH'];
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if (!$length) {
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return;
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}
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// Time to fatal: we know this was a POST with data that should have been
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// populated into $_POST, but it wasn't.
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$config = ini_get('post_max_size');
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PhabricatorStartup::didFatal(
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"As received by the server, this request had a nonzero content length ".
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"but no POST data.\n\n".
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"Normally, this indicates that it exceeds the 'post_max_size' setting ".
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"in the PHP configuration on the server. Increase the 'post_max_size' ".
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"setting or reduce the size of the request.\n\n".
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"Request size according to 'Content-Length' was '{$length}', ".
|
|
"'post_max_size' is set to '{$config}'.");
|
|
}
|
|
|
|
|
|
/* -( Rate Limiting )------------------------------------------------------ */
|
|
|
|
|
|
/**
|
|
* Adjust the permissible rate limit score.
|
|
*
|
|
* By default, the limit is `1000`. You can use this method to set it to
|
|
* a larger or smaller value. If you set it to `2000`, users may make twice
|
|
* as many requests before rate limiting.
|
|
*
|
|
* @param int Maximum score before rate limiting.
|
|
* @return void
|
|
* @task ratelimit
|
|
*/
|
|
public static function setMaximumRate($rate) {
|
|
self::$maximumRate = $rate;
|
|
}
|
|
|
|
|
|
/**
|
|
* Check if the user (identified by `$user_identity`) has issued too many
|
|
* requests recently. If they have, end the request with a 429 error code.
|
|
*
|
|
* The key just needs to identify the user. Phabricator uses both user PHIDs
|
|
* and user IPs as keys, tracking logged-in and logged-out users separately
|
|
* and enforcing different limits.
|
|
*
|
|
* @param string Some key which identifies the user making the request.
|
|
* @return void If the user has exceeded the rate limit, this method
|
|
* does not return.
|
|
* @task ratelimit
|
|
*/
|
|
public static function rateLimitRequest($user_identity) {
|
|
if (!self::canRateLimit()) {
|
|
return;
|
|
}
|
|
|
|
$score = self::getRateLimitScore($user_identity);
|
|
if ($score > (self::$maximumRate * self::getRateLimitBucketCount())) {
|
|
// Give the user some bonus points for getting rate limited. This keeps
|
|
// bad actors who keep slamming the 429 page locked out completely,
|
|
// instead of letting them get a burst of requests through every minute
|
|
// after a bucket expires.
|
|
self::addRateLimitScore($user_identity, 50);
|
|
self::didRateLimit($user_identity);
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Add points to the rate limit score for some user.
|
|
*
|
|
* If users have earned more than 1000 points per minute across all the
|
|
* buckets they'll be locked out of the application, so awarding 1 point per
|
|
* request roughly corresponds to allowing 1000 requests per second, while
|
|
* awarding 50 points roughly corresponds to allowing 20 requests per second.
|
|
*
|
|
* @param string Some key which identifies the user making the request.
|
|
* @param float The cost for this request; more points pushes them toward
|
|
* the limit faster.
|
|
* @return void
|
|
* @task ratelimit
|
|
*/
|
|
public static function addRateLimitScore($user_identity, $score) {
|
|
if (!self::canRateLimit()) {
|
|
return;
|
|
}
|
|
|
|
$current = self::getRateLimitBucket();
|
|
|
|
// There's a bit of a race here, if a second process reads the bucket before
|
|
// this one writes it, but it's fine if we occasionally fail to record a
|
|
// user's score. If they're making requests fast enough to hit rate
|
|
// limiting, we'll get them soon.
|
|
|
|
$bucket_key = self::getRateLimitBucketKey($current);
|
|
$bucket = apc_fetch($bucket_key);
|
|
if (!is_array($bucket)) {
|
|
$bucket = array();
|
|
}
|
|
|
|
if (empty($bucket[$user_identity])) {
|
|
$bucket[$user_identity] = 0;
|
|
}
|
|
|
|
$bucket[$user_identity] += $score;
|
|
apc_store($bucket_key, $bucket);
|
|
}
|
|
|
|
|
|
/**
|
|
* Determine if rate limiting is available.
|
|
*
|
|
* Rate limiting depends on APC, and isn't available unless the APC user
|
|
* cache is available.
|
|
*
|
|
* @return bool True if rate limiting is available.
|
|
* @task ratelimit
|
|
*/
|
|
private static function canRateLimit() {
|
|
if (!self::$maximumRate) {
|
|
return false;
|
|
}
|
|
|
|
if (!function_exists('apc_fetch')) {
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
/**
|
|
* Get the current bucket for storing rate limit scores.
|
|
*
|
|
* @return int The current bucket.
|
|
* @task ratelimit
|
|
*/
|
|
private static function getRateLimitBucket() {
|
|
return (int)(time() / 60);
|
|
}
|
|
|
|
|
|
/**
|
|
* Get the total number of rate limit buckets to retain.
|
|
*
|
|
* @return int Total number of rate limit buckets to retain.
|
|
* @task ratelimit
|
|
*/
|
|
private static function getRateLimitBucketCount() {
|
|
return 5;
|
|
}
|
|
|
|
|
|
/**
|
|
* Get the APC key for a given bucket.
|
|
*
|
|
* @param int Bucket to get the key for.
|
|
* @return string APC key for the bucket.
|
|
* @task ratelimit
|
|
*/
|
|
private static function getRateLimitBucketKey($bucket) {
|
|
return 'rate:bucket:'.$bucket;
|
|
}
|
|
|
|
|
|
/**
|
|
* Get the APC key for the smallest stored bucket.
|
|
*
|
|
* @return string APC key for the smallest stored bucket.
|
|
* @task ratelimit
|
|
*/
|
|
private static function getRateLimitMinKey() {
|
|
return 'rate:min';
|
|
}
|
|
|
|
|
|
/**
|
|
* Get the current rate limit score for a given user.
|
|
*
|
|
* @param string Unique key identifying the user.
|
|
* @return float The user's current score.
|
|
* @task ratelimit
|
|
*/
|
|
private static function getRateLimitScore($user_identity) {
|
|
$min_key = self::getRateLimitMinKey();
|
|
|
|
// Identify the oldest bucket stored in APC.
|
|
$cur = self::getRateLimitBucket();
|
|
$min = apc_fetch($min_key);
|
|
|
|
// If we don't have any buckets stored yet, store the current bucket as
|
|
// the oldest bucket.
|
|
if (!$min) {
|
|
apc_store($min_key, $cur);
|
|
$min = $cur;
|
|
}
|
|
|
|
// Destroy any buckets that are older than the minimum bucket we're keeping
|
|
// track of. Under load this normally shouldn't do anything, but will clean
|
|
// up an old bucket once per minute.
|
|
$count = self::getRateLimitBucketCount();
|
|
for ($cursor = $min; $cursor < ($cur - $count); $cursor++) {
|
|
apc_delete(self::getRateLimitBucketKey($cursor));
|
|
apc_store($min_key, $cursor + 1);
|
|
}
|
|
|
|
// Now, sum up the user's scores in all of the active buckets.
|
|
$score = 0;
|
|
for (; $cursor <= $cur; $cursor++) {
|
|
$bucket = apc_fetch(self::getRateLimitBucketKey($cursor));
|
|
if (isset($bucket[$user_identity])) {
|
|
$score += $bucket[$user_identity];
|
|
}
|
|
}
|
|
|
|
return $score;
|
|
}
|
|
|
|
|
|
/**
|
|
* Emit an HTTP 429 "Too Many Requests" response (indicating that the user
|
|
* has exceeded application rate limits) and exit.
|
|
*
|
|
* @return exit This method **does not return**.
|
|
* @task ratelimit
|
|
*/
|
|
private static function didRateLimit() {
|
|
$message =
|
|
"TOO MANY REQUESTS\n".
|
|
"You are issuing too many requests too quickly.\n".
|
|
"To adjust limits, see \"Configuring a Preamble Script\" in the ".
|
|
"documentation.";
|
|
|
|
header(
|
|
'Content-Type: text/plain; charset=utf-8',
|
|
$replace = true,
|
|
$http_error = 429);
|
|
|
|
echo $message;
|
|
|
|
exit(1);
|
|
}
|
|
|
|
}
|