Initial implementation

.eslintrc

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+{
+ "extends": "loopback"
+}

.travis.yml

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+sudo: false
+language: node_js
+node_js:
+ - "0.10"
+ - "0.12"
+ - "4"
+ - "6"

LICENSE.md

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+Copyright (c) IBM Corp. 2016. All Rights Reserved.
+Node module: strong-error-handler
+This project is licensed under the MIT License, full text below.
+
+--------
+
+MIT license
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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-# strong-error-handler
+# strong-error-handler
+
+Error handler for use in development (debug) and production environments.
+
+ - When run in production mode, error responses are purposely undetailed
+ in order to prevent leaking sensitive information.
+
+ - When in debug mode, detailed information such as stack traces
+ are returned in the HTTP responses.
+
+JSON is the only supported response format at this time.
+
+*There are plans to support other formats such as Text, HTML, and XML.*
+
+## Install
+
+```bash
+$ npm install strong-error-handler
+```
+
+## Usage
+
+In an express-based application:
+
+```js
+var express = require('express');
+var errorHandler = require('strong-error-handler');
+
+var app = express();
+// setup your routes
+app.use(errorHandler({ /* options, see below */ }));
+
+app.listen(3000);
+```
+
+In LoopBack applications, add the following entry to your
+`server/middleware.json` file.
+
+```json
+{
+ "final:after": {
+ "strong-error-handler": {
+ "params": {
+ }
+ }
+ }
+}
+```
+
+## Options
+
+#### debug
+
+`boolean`, defaults to `false`.
+
+When enabled, HTTP responses include all error properties, including
+sensitive data such as file paths, URLs and stack traces.
+
+#### log
+
+`boolean`, defaults to `true`.
+
+When enabled, all errors are printed via `console.error`.
+
+Customization of the log format is intentionally not allowed. If you would like
+to use a different format/logger, disable this option and add your own custom
+error-handling middleware.
+
+```js
+app.use(myErrorLogger());
+app.use(errorHandler({ log: false }));
+```

lib/data-builder.js

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+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-error-handler
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+var httpStatus = require('http-status');
+
+module.exports = function buildResponseData(err, isDebugMode) {
+ if (Array.isArray(err) && isDebugMode) {
+ err = serializeArrayOfErrors(err);
+ }
+
+ var data = Object.create(null);
+ fillStatusCode(data, err);
+
+ if (typeof err !== 'object') {
+ data.statusCode = 500;
+ data.message = '' + err;
+ err = {};
+ }
+
+ if (isDebugMode) {
+ fillDebugData(data, err);
+ } else if (data.statusCode >= 400 && data.statusCode <= 499) {
+ fillBadRequestError(data, err);
+ } else {
+ fillInternalError(data, err);
+ }
+
+ return data;
+};
+
+function serializeArrayOfErrors(errors) {
+ var details = [];
+ for (var ix in errors) {
+ var err = errors[ix];
+ if (typeof err !== 'object') {
+ details.push('' + err);
+ continue;
+ }
+
+ var data = {stack: err.stack};
+ for (var p in err) { // eslint-disable-line one-var
+ data[p] = err[p];
+ }
+ details.push(data);
+ }
+
+ return {
+ name: 'ArrayOfErrors',
+ message: 'Failed with multiple errors, ' +
+ 'see `details` for more information.',
+ details: details,
+ };
+}
+
+function fillStatusCode(data, err) {
+ data.statusCode = err.statusCode || err.status;
+ if (!data.statusCode || data.statusCode < 400)
+ data.statusCode = 500;
+}
+
+function fillDebugData(data, err) {
+ for (var p in err) {
+ if ((p in data)) continue;
+ data[p] = err[p];
+ }
+ // NOTE err.stack is not an enumerable property
+ data.stack = err.stack;
+}
+
+function fillBadRequestError(data, err) {
+ data.name = err.name;
+ data.message = err.message;
+ data.details = err.details;
+}
+
+function fillInternalError(data, err) {
+ data.message = httpStatus[data.statusCode] || 'Unknown Error';
+}

lib/handler.js

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+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-error-handler
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+var buildResponseData = require('./data-builder');
+var debug = require('debug')('strong-error-handler');
+var format = require('util').format;
+var logToConsole = require('./logger');
+var sendJson = require('./send-json');
+
+function noop() {
+}
+
+/**
+ * Create a middleware error handler function.
+ *
+ * @param {Object} options
+ * @returns {Function}
+ */
+exports = module.exports = function createStrongErrorHandler(options) {
+ options = options || {};
+
+ debug('Initializing with options %j', options);
+
+ // Debugging mode is disabled by default. When turned on (in dev),
+ // all error properties (including) stack traces are sent in the response
+ var isDebugMode = options.debug;
+
+ // Log all errors via console.error (enabled by default)
+ var logError = options.log !== false ? logToConsole : noop;
+
+ return function strongErrorHandler(err, req, res, next) {
+ debug('Handling %s', err.stack || err);
+
+ logError(req, err);
+
+ if (res._header) {
+ debug('Response was already sent, closing the underlying connection');
+ return req.socket.destroy();
+ }
+
+ var data = buildResponseData(err, isDebugMode);
+ debug('Response status %s data %j', data.statusCode, data);
+
+ res.setHeader('X-Content-Type-Options', 'nosniff');
+ res.statusCode = data.statusCode;
+
+ // TODO: negotiate the content-type, take into account options.defaultType
+ // For now, we always return JSON. See
+ // - https://github.com/strongloop/strong-error-handler/issues/4
+ // - https://github.com/strongloop/strong-error-handler/issues/5
+ // - https://github.com/strongloop/strong-error-handler/issues/6
+ sendJson(res, data);
+ };
+};

lib/logger.js

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+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-error-handler
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+var format = require('util').format;
+
+module.exports = function logToConsole(req, err) {
+ if (!Array.isArray(err)) {
+ console.error('Unhandled error for request %s %s: %s',
+ req.method, req.url, err.stack || err);
+ return;
+ }
+
+ var errors = err.map(formatError).join('\n');
+ console.error('Unhandled array of errors for request %s %s\n',
+ req.method, req.url, errors);
+};
+
+function formatError(err) {
+ return format('%s', err.stack || err);
+}

lib/send-json.js

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+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-error-handler
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+module.exports = function sendJson(res, data) {
+ var content = JSON.stringify({error: data});
+ res.setHeader('Content-Type', 'application/json; charset=utf-8');
+ res.end(content, 'utf-8');
+};

package.json

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+{
+ "name": "strong-error-handler",
+ "description": "Error handler for use in development and production environments.",
+ "license": "MIT",
+ "version": "1.0.0",
+ "repository": {
+ "type": "git",
+ "url": "https://github.com/strongloop/strong-error-handler.git"
+ },
+ "main": "lib/handler.js",
+ "scripts": {
+ "lint": "eslint .",
+ "test": "mocha",
+ "posttest": "npm run lint"
+ },
+ "dependencies": {
+ "debug": "^2.2.0",
+ "http-status": "^0.2.2"
+ },
+ "devDependencies": {
+ "chai": "^2.1.1",
+ "eslint": "^2.5.3",
+ "eslint-config-loopback": "^3.0.0",
+ "mocha": "^2.1.0",
+ "supertest": "^1.1.0"
+ }
+}