halfmoon / lib / rescuer.php

<?php
/*
	error and exception handling, logging, and notification
*/

namespace HalfMoon;

class StringMaskedDuringRescue {
	private $string;
	public $masked;

	public function __construct($s, $mask = "[hidden]") {
		$this->string = $s;
		$this->masked = $mask;
	}

	public function __toString() {
		return $this->string;
	}
}

class Rescuer {
	static $already_rescued = false;

	/* exceptions that won't trigger an email in notify_of_exception() */
	static $exceptions_to_suppress = array(
		'\HalfMoon\RoutingException',
		'\HalfMoon\InvalidAuthenticityToken',
		'\HalfMoon\UndefinedFunction',
		'\HalfMoon\BadRequest',
		'\ActiveRecord\RecordNotFound',
	);

	static function error_handler($errno, $errstr, $errfile, $errline) {
		return Rescuer::shutdown_error_handler(array(
			"type" => $errno,
			"message" => $errstr,
			"file" => $errfile,
			"line" => $errline,
		));
	}

	/* handle after-shutdown errors (like parse errors) */
	static function shutdown_error_handler($error = null) {
		if (is_null($error))
			if (is_null($error = error_get_last()))
				return;

		/* if this shouldn't be reported at all, just bail */
		if (!((bool)($error["type"] & ini_get("error_reporting"))))
			return;

		$exception = new \ErrorException($error["message"], 0, $error["type"],
			$error["file"], $error["line"]);

		$title = $error["message"] . " in " . $error["file"] . " on line "
			. $error["line"];

		/* everything according to the error_reporting ini value should be
		 * logged */
		Rescuer::log_exception($exception, $title, $request = null);

		Rescuer::notify_of_exception($exception, $title, $request);

		/* if it's a major/fatal problem (according to
		 * http://php.net/manual/en/errorfunc.constants.php), then we should
		 * show the user an error page and exit */
		if (in_array($error["type"], array(E_ERROR, E_PARSE, E_CORE_ERROR,
		E_COMPILE_ERROR, E_USER_ERROR, E_RECOVERABLE_ERROR)))
			return Rescuer::rescue_in_public($exception, $title, $request);
	}

	/* handle exceptions by logging them, notifying about them (if we're in
	 * production), and then showing the user an error page */
	static function rescue_exception($exception, $request = null) {
		$title = get_class($exception);

		/* activerecord includes the stack trace in the message, so strip it
		 * out */
		if ($exception instanceof \ActiveRecord\DatabaseException)
			$title .= ": " . preg_replace("/\nStack trace:.*/s", "",
				$exception->getMessage());
		elseif ($exception->getMessage())
			$title .= ": " . $exception->getMessage() . " in "
				. $exception->getFile() . " on line " . $exception->getLine();

		Rescuer::log_exception($exception, $title, $request);

		Rescuer::notify_of_exception($exception, $title, $request);

		if (php_sapi_name() == "cli")
			exit(1);
		else
			return Rescuer::rescue_in_public($exception, $title, $request);
	}

	/* log an exception, mail it, try to show the user something */
	static function log_exception($exception, $title, $request) {
		Log::error($title . ":");

		if (!is_null($exception) && is_object($exception))
			foreach (static::masked_stack_trace($exception) as $line)
				Log::error($line);

		return;
	}

	static function masked_stack_trace($exception, $html = false) {
		$trace = array();

		foreach ($exception->getTrace() as $call) {
			$out = "";

			if (!$html)
				$out .= "    ";

			if (isset($call["file"])) {
				$call["file"] = preg_replace("/^" . preg_quote(HALFMOON_ROOT,
					"/") . "\/?/", "", $call["file"]);

				if ($html) {
					$fileparts = explode("/", $call["file"]);

					for ($x = 0; $x < count($fileparts); $x++) {
						$fileparts[$x] = h($fileparts[$x]);

						if ($x == count($fileparts) - 1)
							$fileparts[$x] = "<strong>" . $fileparts[$x]
								. "</strong>";
					}

					$out .= join("/", $fileparts);
				} else
					$out .= $call["file"];
			}

			elseif (isset($call["class"]))
				$out .= $call["class"];

			else
				$out .= "unknown";

			$out .= ":";

			if (isset($call["line"]))
				$out .= $call["line"];

			$out .= " in ";

			if ($html)
				$out .= "<strong>" . h($call["function"]) . "(</strong>";
			else
				$out .= $call["function"] . "(";

			foreach ($call["args"] as $x => $arg) {
				if ($x)
					$out .= ", ";

				$m = static::_mask_object($arg);
				if ($html)
					$out .= h($m);
				else
					$out .= $m;
			}

			$out .= ($html ? "<strong>)</strong>" : ")");

			array_push($trace, $out);
		}

		return $trace;
	}

	static function _mask_object($obj) {
		$out = null;

		if (is_object($obj) &&
		get_class($obj) == "HalfMoon\\StringMaskedDuringRescue")
			$out = "'" . $obj->masked . "'";

		elseif (is_object($obj))
			$out = get_class($obj) . (method_exists($obj, "__toString") ?
				"(" . (string)$obj . ")" : "");

		elseif (is_string($obj))
			$out = "'" . $obj . "'";

		elseif (is_array($obj)) {
			$out = "[";

			$assoc = \HalfMoon\Utils::is_assoc($obj);

			$t = array();
			foreach ($obj as $k => $v)
				array_push($t, ($assoc ? $k . ":" : "")
					. static::_mask_object($v));

			$out .= join(", ", $t) . "]";
		}

		else
			$out = (string)$obj;

		return $out;
	}

	/* mail off the details of the exception */
	static function notify_of_exception($exception, $title, $request) {
		if (HALFMOON_ENV != "production")
			return;

		if (static::$already_rescued)
			return;

		foreach (static::$exceptions_to_suppress as $e)
			if ($exception instanceof $e)
				return;

		$config = Config::instance();

		if (!isset($config->exception_notification_recipient))
			return;

		/* render the text template and mail it off */
		@ob_end_clean();
		@ob_start();
		@require(HALFMOON_ROOT . "/halfmoon/lib/rescue.ptxt");
		$mail_body = trim(@ob_get_contents());
		@ob_end_clean();

		@mail($config->exception_notification_recipient,
			$config->exception_notification_subject . " " . $title,
			$mail_body);

		static::$already_rescued = true;

		return;
	}

	/* return a friendly error page to the user (or a full one with debugging
	 * if we're in development mode with display_errors turned on) */
	static function rescue_in_public($exception, $title, $request) {
		/* kill all buffered output */
		while (count(@ob_list_handlers()))
			@ob_end_clean();

		if (HALFMOON_ENV == "development" && ini_get("display_errors"))
			require_once(__DIR__ . "/rescue.phtml");
		else {
			/* production mode, try to handle gracefully */

			if ($exception instanceof \HalfMoon\RoutingException ||
			$exception instanceof \HalfMoon\UndefinedFunction ||
			$exception instanceof \ActiveRecord\RecordNotFound) {
				Request::send_status_header(404);

				if (file_exists($f = HALFMOON_ROOT . "/public/404.html")) {
					Log::error("Rendering " . $f);
					require_once($f);
				} else {
					/* failsafe */
					?>
					<html>
					<head>
					<title>File Not Found</title>
					</head>
					<body>
					<h1>File Not Found</h1>
					The file you requested could not be found.  An additional
					error occured while processing the error document.
					</body>
					</html>
					<?php
				}
			}

			elseif ($exception instanceof \HalfMoon\BadRequest) {
				Request::send_status_header(400);

				if (file_exists($f = HALFMOON_ROOT . "/public/400.html")) {
					Log::error("Rendering " . $f);
					require_once($f);
				}
			}

			elseif ($exception instanceof \HalfMoon\InvalidAuthenticityToken) {
				/* be like rails and give the odd 422 status */
				Request::send_status_header(422);

				if (file_exists($f = HALFMOON_ROOT . "/public/422.html")) {
					Log::error("Rendering " . $f);
					require_once($f);
				} else {
					/* failsafe */
					?>
					<html>
					<head>
					<title>Change Rejected</title>
					</head>
					<body>
					<h1>Change Rejected</h1>
					The change you submitted was rejected due to a security
					problem.  An additional error occured while processing the
					error document.
					</body>
					</html>
					<?php
				}
			}

			else {
				Request::send_status_header(500);

				if (file_exists($f = HALFMOON_ROOT . "/public/500.html")) {
					Log::error("Rendering " . $f);
					require_once($f);
				} else {
					/* failsafe */
					?>
					<html>
					<head>
					<title>Application Error</title>
					</head>
					<body>
					<h1>Application Error</h1>
					An internal application error occured while processing your
					request.  Additionally, an error occured while processing
					the error document.
					</body>
					</html>
					<?php
				}
			}
		}

		static::$already_rescued = true;

		/* that's it, end of the line */
		exit;
	}
}

/* make traditional errors throw exceptions so we can handle everything in one
 * place */
set_error_handler(array("\\HalfMoon\\Rescuer", "error_handler"));

/* catch errors on the cleanup that we couldn't handle at runtime */
register_shutdown_function(array("\\HalfMoon\\Rescuer",
	"shutdown_error_handler"));

/* and catch all exceptions */
set_exception_handler(array("\\HalfMoon\\Rescuer", "rescue_exception"));

?>