Repository: koajs/koa
File: lib/application.js (JavaScript)

Code before:

'use strict';

/**
 * Module dependencies.
 */

const isGeneratorFunction = require('is-generator-function');
const debug = require('debug')('koa:application');
const onFinished = require('on-finished');
const response = require('./response');
const compose = require('koa-compose');
const isJSON = require('koa-is-json');
const context = require('./context');
const request = require('./request');
const statuses = require('statuses');
const Cookies = require('cookies');
const accepts = require('accepts');
const Emitter = require('events');
const assert = require('assert');
const Stream = require('stream');
const http = require('http');
const only = require('only');
const convert = require('koa-convert');
const deprecate = require('depd')('koa');

/**
 * Expose `Application` class.
 * Inherits from `Emitter.prototype`.
 */

module.exports = class Application extends Emitter {

  /**
   * Initialize a new `Application`.
   *
   * @api public
   */

  constructor() {
    super();

    this.proxy = false;
    this.middleware = [];
    this.subdomainOffset = 2;
    this.env = process.env.NODE_ENV || 'development';
    this.context = Object.create(context);
    this.request = Object.create(request);
    this.response = Object.create(response);
  }

  /**
   * Shorthand for:
   *
   *    http.createServer(app.callback()).listen(...)
   *
   * @param {Mixed} ...
   * @return {Server}
   * @api public
   */

  listen() {
    debug('listen');
    const server = http.createServer(this.callback());
    return server.listen.apply(server, arguments);
  }

  /**
   * Return JSON representation.
   * We only bother showing settings.
   *
   * @return {Object}
   * @api public
   */

  toJSON() {
    return only(this, [
      'subdomainOffset',
      'proxy',
      'env'
    ]);
  }

  /**
   * Inspect implementation.
   *
   * @return {Object}
   * @api public
   */

  inspect() {
    return this.toJSON();
  }

  /**
   * Use the given middleware `fn`.
   *
   * Old-style middleware will be converted.
   *
   * @param {Function} fn
   * @return {Application} self
   * @api public
   */

  use(fn) {
    if (typeof fn !== 'function') throw new TypeError('middleware must be a function!');
    if (isGeneratorFunction(fn)) {
      deprecate('Support for generators will been removed in v3. ' +
                'See the documentation for examples of how to convert old middleware ' +
                'https://github.com/koajs/koa/tree/v2.x#old-signature-middleware-v1x');
      fn = convert(fn);
    }
    debug('use %s', fn._name || fn.name || '-');
    this.middleware.push(fn);
    return this;
  }

  /**
   * Return a request handler callback
   * for node's native http server.
   *
   * @return {Function}
   * @api public
   */

  callback() {
    const fn = compose(this.middleware);

    if (!this.listeners('error').length) this.on('error', this.onerror);

    return (req, res) => {
      res.statusCode = 404;
      const ctx = this.createContext(req, res);
      onFinished(res, ctx.onerror);
      fn(ctx).then(() => respond(ctx)).catch(ctx.onerror);
    };
  }

  /**
   * Initialize a new context.
   *
   * @api private
   */

  createContext(req, res) {
    const context = Object.create(this.context);
    const request = context.request = Object.create(this.request);
    const response = context.response = Object.create(this.response);
    context.app = request.app = response.app = this;
    context.req = request.req = response.req = req;
    context.res = request.res = response.res = res;
    request.ctx = response.ctx = context;
    request.response = response;
    response.request = request;
    context.onerror = context.onerror.bind(context);
    context.originalUrl = request.originalUrl = req.url;
    context.cookies = new Cookies(req, res, {
      keys: this.keys,
      secure: request.secure
    });
    if (req && req.headers) {
      request.ip = request.ips[0] || req.socket.remoteAddress || '';
    } else {
      request.ip = ''; // We are in a badly written test :P
    }
    context.accept = request.accept = accepts(req);
    context.state = {};
    return context;
  }

  /**
   * Default error handler.
   *
   * @param {Error} err
   * @api private
   */

  onerror(err) {
    assert(err instanceof Error, `non-error thrown: ${err}`);

    if (404 == err.status || err.expose) return;
    if (this.silent) return;

    const msg = err.stack || err.toString();
    console.error();
    console.error(msg.replace(/^/gm, '  '));
    console.error();
  }

};

/**
 * Response helper.
 */

function respond(ctx) {
  // allow bypassing koa
  if (false === ctx.respond) return;

  const res = ctx.res;
  if (!ctx.writable) return;

  let body = ctx.body;
  const code = ctx.status;

  // ignore body
  if (statuses.empty[code]) {
    // strip headers
    ctx.body = null;
    return res.end();
  }

  if ('HEAD' == ctx.method) {
    if (!res.headersSent && isJSON(body)) {
      ctx.length = Buffer.byteLength(JSON.stringify(body));
    }
    return res.end();
  }

  // status body
  if (null == body) {
    body = ctx.message || String(code);
    if (!res.headersSent) {
      ctx.type = 'text';
      ctx.length = Buffer.byteLength(body);
    }
    return res.end(body);
  }

  // responses
  if (Buffer.isBuffer(body)) return res.end(body);
  if ('string' == typeof body) return res.end(body);
  if (body instanceof Stream) return body.pipe(res);

  // body: json
  body = JSON.stringify(body);
  if (!res.headersSent) {
    ctx.length = Buffer.byteLength(body);
  }
  res.end(body);
}


Review comment (suggestion):
This could remove rate limiting if the attacker doesn't need the result of the request. I'd prefer we don't handle the request. However, the impact is minimal so I'll change it back to `|| ''` unless anybody else has a comment.


Code after:

'use strict';

/**
 * Module dependencies.
 */

const isGeneratorFunction = require('is-generator-function');
const debug = require('debug')('koa:application');
const onFinished = require('on-finished');
const response = require('./response');
const compose = require('koa-compose');
const isJSON = require('koa-is-json');
const context = require('./context');
const request = require('./request');
const statuses = require('statuses');
const Cookies = require('cookies');
const accepts = require('accepts');
const Emitter = require('events');
const assert = require('assert');
const Stream = require('stream');
const http = require('http');
const only = require('only');
const convert = require('koa-convert');
const deprecate = require('depd')('koa');

/**
 * Expose `Application` class.
 * Inherits from `Emitter.prototype`.
 */

module.exports = class Application extends Emitter {

  /**
   * Initialize a new `Application`.
   *
   * @api public
   */

  constructor() {
    super();

    this.proxy = false;
    this.middleware = [];
    this.subdomainOffset = 2;
    this.env = process.env.NODE_ENV || 'development';
    this.context = Object.create(context);
    this.request = Object.create(request);
    this.response = Object.create(response);
  }

  /**
   * Shorthand for:
   *
   *    http.createServer(app.callback()).listen(...)
   *
   * @param {Mixed} ...
   * @return {Server}
   * @api public
   */

  listen() {
    debug('listen');
    const server = http.createServer(this.callback());
    return server.listen.apply(server, arguments);
  }

  /**
   * Return JSON representation.
   * We only bother showing settings.
   *
   * @return {Object}
   * @api public
   */

  toJSON() {
    return only(this, [
      'subdomainOffset',
      'proxy',
      'env'
    ]);
  }

  /**
   * Inspect implementation.
   *
   * @return {Object}
   * @api public
   */

  inspect() {
    return this.toJSON();
  }

  /**
   * Use the given middleware `fn`.
   *
   * Old-style middleware will be converted.
   *
   * @param {Function} fn
   * @return {Application} self
   * @api public
   */

  use(fn) {
    if (typeof fn !== 'function') throw new TypeError('middleware must be a function!');
    if (isGeneratorFunction(fn)) {
      deprecate('Support for generators will been removed in v3. ' +
                'See the documentation for examples of how to convert old middleware ' +
                'https://github.com/koajs/koa/tree/v2.x#old-signature-middleware-v1x');
      fn = convert(fn);
    }
    debug('use %s', fn._name || fn.name || '-');
    this.middleware.push(fn);
    return this;
  }

  /**
   * Return a request handler callback
   * for node's native http server.
   *
   * @return {Function}
   * @api public
   */

  callback() {
    const fn = compose(this.middleware);

    if (!this.listeners('error').length) this.on('error', this.onerror);

    return (req, res) => {
      res.statusCode = 404;
      const ctx = this.createContext(req, res);
      onFinished(res, ctx.onerror);
      fn(ctx).then(() => respond(ctx)).catch(ctx.onerror);
    };
  }

  /**
   * Initialize a new context.
   *
   * @api private
   */

  createContext(req, res) {
    const context = Object.create(this.context);
    const request = context.request = Object.create(this.request);
    const response = context.response = Object.create(this.response);
    context.app = request.app = response.app = this;
    context.req = request.req = response.req = req;
    context.res = request.res = response.res = res;
    request.ctx = response.ctx = context;
    request.response = response;
    response.request = request;
    context.onerror = context.onerror.bind(context);
    context.originalUrl = request.originalUrl = req.url;
    context.cookies = new Cookies(req, res, {
      keys: this.keys,
      secure: request.secure
    });
    request.ip = request.ips[0] || req.socket.remoteAddress || '';
    context.accept = request.accept = accepts(req);
    context.state = {};
    return context;
  }

  /**
   * Default error handler.
   *
   * @param {Error} err
   * @api private
   */

  onerror(err) {
    assert(err instanceof Error, `non-error thrown: ${err}`);

    if (404 == err.status || err.expose) return;
    if (this.silent) return;

    const msg = err.stack || err.toString();
    console.error();
    console.error(msg.replace(/^/gm, '  '));
    console.error();
  }

};

/**
 * Response helper.
 */

function respond(ctx) {
  // allow bypassing koa
  if (false === ctx.respond) return;

  const res = ctx.res;
  if (!ctx.writable) return;

  let body = ctx.body;
  const code = ctx.status;

  // ignore body
  if (statuses.empty[code]) {
    // strip headers
    ctx.body = null;
    return res.end();
  }

  if ('HEAD' == ctx.method) {
    if (!res.headersSent && isJSON(body)) {
      ctx.length = Buffer.byteLength(JSON.stringify(body));
    }
    return res.end();
  }

  // status body
  if (null == body) {
    body = ctx.message || String(code);
    if (!res.headersSent) {
      ctx.type = 'text';
      ctx.length = Buffer.byteLength(body);
    }
    return res.end(body);
  }

  // responses
  if (Buffer.isBuffer(body)) return res.end(body);
  if ('string' == typeof body) return res.end(body);
  if (body instanceof Stream) return body.pipe(res);

  // body: json
  body = JSON.stringify(body);
  if (!res.headersSent) {
    ctx.length = Buffer.byteLength(body);
  }
  res.end(body);
}