git.squeep.com Git - squeep-api-dingus/blob - lib/dingus.js

   1 /* eslint-disable security/detect-object-injection */
   2 'use strict';
   3
   4 /**
   5  * A very minimal API server framework.
   6  * Just a self-contained router and some request glue.
   7  */
   8
   9 require('./patches');
  10 const { promises: fsPromises } = require('fs');
  11 const path = require('path');
  12 const querystring = require('querystring');
  13 const common = require('./common');
  14 const ContentNegotiation = require('./content-negotiation');
  15 const Enum = require('./enum');
  16 const { DingusError, ResponseError, RouterNoMethodError, RouterNoPathError } = require('./errors');
  17 const { extensionToMime } = require('./mime-helper');
  18 const Router = require('./router');
  19 const Template = require('./template');
  20
  21 // For logging.
  22 const _fileScope = common.fileScope(__filename);
  23
  24 const defaultOptions = {
  25   ignoreTrailingSlash: true,
  26   proxyPrefix: '',
  27   strictAccept: true,
  28   selfBaseUrl: '',
  29   staticMetadata: true,
  30   staticPath: undefined, // No reasonable default
  31   trustProxy: true,
  32   querystring,
  33 };
  34
  35 class Dingus {
  36   /**
  37    * @param {Object} logger object which implements logging methods
  38    * @param {Object} options
  39    * @param {Boolean} options.ignoreTrailingSlash requests for '/foo/' will match a '/foo' route
  40    * @param {string} options.proxyPrefix leading part of url path to strip
  41    * @param {Boolean} options.strictAccept whether to error on unsupported Accept type
  42    * @param {string} options.selfBaseUrl for constructing links
  43    * @param {Boolean} options.staticMetadata serve static headers with static files
  44    * @param {Boolean} options.trustProxy trust some header data to be provided by proxy
  45    * @param {Object} options.querystring alternate qs parser to use
  46    */
  47   constructor(logger = console, options = {}) {
  48     common.setOptions(this, defaultOptions, options);
  49
  50     this.router = new Router(options);
  51
  52     if (!this.proxyPrefix) {
  53       this._stripPrefix = (p) => p;
  54     }
  55
  56     this.responseTypes = [
  57       Enum.ContentType.TextHTML,
  58       Enum.ContentType.TextPlain,
  59       Enum.ContentType.ApplicationJson,
  60     ];
  61
  62     this.logger = logger;
  63   }
  64
  65
  66   /**
  67    * Resolve relative and empty paths in url
  68    * @param {string} p path
  69    */
  70   _normalizePath(p) {
  71     const pathNorm = path.normalize(p); // This isn't perfectly correct, but it's easy...
  72     return this._stripPrefix(pathNorm);
  73   }
  74
  75
  76   /**
  77    * Remove a leading portion of url path
  78    * N.B. This method gets obliterated if there is no prefix defined at construction
  79    * @param {string} p path
  80    */
  81   _stripPrefix(p) {
  82     if (p.startsWith(this.proxyPrefix)) {
  83       return p.slice(this.proxyPrefix.length);
  84     }
  85     return p;
  86   }
  87
  88
  89   /**
  90    * Returns the path part, and querystring object, from a request url.
  91    * @param {string} url
  92    */
  93   _splitUrl(url) {
  94     const [ p, qs ] = common.splitFirst(url, '?');
  95     return {
  96       pathPart: this._normalizePath(p),
  97       queryParams: this.querystring.parse(qs),
  98     };
  99   }
 100
 101
 102   /**
 103    * Insert a new path handler
 104    * @param {string} method
 105    * @param {string} urlPath
 106    * @param {fn} handler
 107    */
 108   on(method, urlPath, handler, ...handlerArgs) {
 109     this.router.on(method, urlPath, handler, handlerArgs);
 110   }
 111
 112
 113   /**
 114    * Common header tagging for all requests.
 115    * Add our own identifier, and persist any external transit identifiers.
 116    * @param {http.ClientRequest} req
 117    * @param {http.ServerResponse} res
 118    * @param {object} ctx
 119    */
 120   static tagContext(req, res, ctx) {
 121     const requestId = common.requestId();
 122     ctx.requestId = requestId;
 123     res.setHeader(Enum.Header.RequestId, requestId);
 124     [Enum.Header.XRequestId, Enum.Header.XCorrelationId].forEach((h) => {
 125       const v = req.getHeader(h);
 126       if (v) {
 127         ctx[h.replace(/-/g, '')] = v;
 128         res.setHeader(h, v);
 129       }
 130     });
 131     return requestId;
 132   }
 133
 134
 135   /**
 136    *
 137    * @param {http.ClientRequest} req
 138    */
 139   _getAddress(req) {
 140     // TODO: RFC7239 Forwarded support
 141     const address = (this.trustProxy && req?.getHeader(Enum.Header.XForwardedFor)) ||
 142       (this.trustProxy && req?.getHeader(Enum.Header.XRealIP)) ||
 143       (req?.connection?.remoteAddress) ||
 144       '';
 145     return address.split(/\s*,\s*/u)[0];
 146   }
 147
 148
 149   /**
 150    *
 151    * @param {http.ClientRequest} req
 152    */
 153   _getProtocol(req) {
 154     // TODO: RFC7239 Forwarded support
 155     const protocol = (this.trustProxy && req?.getHeader(Enum.Header.XForwardedProto)) ||
 156       ((req?.connection?.encrypted) ? 'https' : 'http');
 157     return protocol.split(/\s*,\s*/u)[0];
 158   }
 159
 160
 161   /**
 162    *
 163    * @param {http.ClientRequest} req
 164    * @param {http.ServerResponse} res
 165    * @param {object} ctx
 166    */
 167   clientAddressContext(req, res, ctx) {
 168     ctx.clientAddress = this._getAddress(req);
 169     ctx.clientProtocol = this._getProtocol(req);
 170   }
 171
 172
 173   /**
 174    * Called before every request handler.
 175    * @param {http.ClientRequest} req
 176    * @param {http.ServerResponse} res
 177    * @param {object} ctx
 178    */
 179   async preHandler(req, res, ctx) {
 180     Dingus.tagContext(req, res, ctx);
 181     this.clientAddressContext(req, res, ctx);
 182   }
 183
 184
 185   /**
 186    * Helper for collecting chunks as array of buffers.
 187    * @param {Buffer[]} chunks
 188    * @param {string|Buffer} chunk
 189    * @param {string} encoding
 190    */
 191   static pushBufChunk(chunks, chunk, encoding = 'utf8') {
 192     if (chunk) {
 193       if (typeof chunk === 'string') {
 194         chunk = Buffer.from(chunk, encoding);
 195       }
 196       chunks.push(chunk);
 197     }
 198   }
 199
 200
 201   /**
 202    * Sets ctx.responseBody and calls handler upon res.end().
 203    * @param {http.ClientRequest} req
 204    * @param {http.ServerResponse} res
 205    * @param {object} ctx
 206    * @param {*} handler fn(req, res, ctx)
 207    */
 208   static setEndBodyHandler(req, res, ctx, handler) {
 209     const origWrite = res.write.bind(res);
 210     const origEnd = res.end.bind(res);
 211     const chunks = [];
 212     res.write = function (chunk, encoding, ...rest) {
 213       Dingus.pushBufChunk(chunks, chunk, encoding);
 214       return origWrite(chunk, encoding, ...rest);
 215     };
 216     res.end = function (data, encoding, ...rest) {
 217       Dingus.pushBufChunk(chunks, data, encoding);
 218       ctx.responseBody = Buffer.concat(chunks);
 219       handler(req, res, ctx);
 220       return origEnd(data, encoding, ...rest);
 221     };
 222   }
 223
 224
 225   /**
 226    * Intercept writes for head requests, do not send to client,
 227    * but send length, and make body available in context.
 228    * N.B. If persisted, ctx.responseBody will be a raw buffer, be aware when logging.
 229    * @param {http.ClientRequest} req
 230    * @param {http.ServerResponse} res
 231    * @param {object} ctx
 232    * @param {Boolean} persistResponseBody
 233    */
 234   static setHeadHandler(req, res, ctx, persistResponseBody = false) {
 235     if (req.method === 'HEAD') {
 236       const origEnd = res.end.bind(res);
 237       const chunks = [];
 238       res.write = function (chunk, encoding) {
 239         Dingus.pushBufChunk(chunks, chunk, encoding);
 240         // No call to original res.write.
 241       };
 242       res.end = function (data, encoding, ...rest) {
 243         Dingus.pushBufChunk(chunks, data, encoding);
 244         const responseBody = Buffer.concat(chunks);
 245         res.setHeader(Enum.Header.ContentLength, Buffer.byteLength(responseBody));
 246         if (persistResponseBody) {
 247           ctx.responseBody = responseBody;
 248         }
 249         return origEnd(undefined, encoding, ...rest);
 250       };
 251     }
 252   }
 253
 254
 255   /**
 256    * Dispatch the handler for a request
 257    * @param {http.ClientRequest} req
 258    * @param {http.ServerResponse} res
 259    * @param {object} ctx
 260    */
 261   async dispatch(req, res, ctx = {}) {
 262     const _scope = _fileScope('dispatch');
 263
 264     const { pathPart, queryParams } = this._splitUrl(req.url);
 265     ctx.queryParams = queryParams;
 266
 267     let handler, handlerArgs = [];
 268     try {
 269       ({ handler, handlerArgs } = this.router.lookup(req.method, pathPart, ctx));
 270     } catch (e) {
 271       if (e instanceof RouterNoPathError) {
 272         handler = this.handlerNotFound.bind(this);
 273       } else if (e instanceof RouterNoMethodError) {
 274         handler = this.handlerMethodNotAllowed.bind(this);
 275       } else if (e instanceof DingusError) {
 276         this.logger.error(_scope, 'unknown dingus error', { error: e });
 277         handler = this.handlerInternalServerError.bind(this);
 278       } else if (e instanceof URIError) {
 279         handler = this.handlerBadRequest.bind(this);
 280       } else {
 281         this.logger.error(_scope, 'lookup failure', { error: e });
 282         handler = this.handlerInternalServerError.bind(this);
 283       }
 284     }
 285
 286     try {
 287       await this.preHandler(req, res, ctx);
 288       return await handler(req, res, ctx, ...handlerArgs);
 289     } catch (e) {
 290       ctx.error = e;
 291       this.sendErrorResponse(e, req, res, ctx);
 292     }
 293   }
 294
 295
 296   /**
 297    * Return normalized type, without any parameters.
 298    * @param {http.ClientRequest} req
 299    * @returns {string}
 300    */
 301   static getRequestContentType(req) {
 302     const contentType = req.getHeader(Enum.Header.ContentType);
 303     return (contentType || '').split(';')[0].trim().toLowerCase();
 304   }
 305
 306
 307   /**
 308    * Parse rawBody as contentType into ctx.parsedBody.
 309    * @param {string} contentType
 310    * @param {object} ctx
 311    * @param {string|buffer} rawBody
 312   */
 313   parseBody(contentType, ctx, rawBody) {
 314     const _scope = _fileScope('parseBody');
 315
 316     switch (contentType) {
 317       case Enum.ContentType.ApplicationForm:
 318         ctx.parsedBody = this.querystring.parse(rawBody);
 319         break;
 320
 321       case Enum.ContentType.ApplicationJson:
 322         try {
 323           ctx.parsedBody = JSON.parse(rawBody);
 324         } catch (e) {
 325           this.logger.debug(_scope, 'JSON parse failed', { requestId: ctx.requestId, error: e });
 326           throw new ResponseError(Enum.ErrorResponse.BadRequest, e.message);
 327         }
 328         break;
 329
 330       default:
 331         this.logger.debug(_scope, 'unhandled content-type', { requestId: ctx.requestId, contentType });
 332         throw new ResponseError(Enum.ErrorResponse.UnsupportedMediaType);
 333     }
 334   }
 335
 336
 337   /**
 338    * Return all body data from a request.
 339    * @param {http.ClientRequest} req
 340    * @param {Number=} maximumBodySize
 341    * @param {Boolean=} toString
 342    */
 343   async bodyData(req, maximumBodySize, toString = true) {
 344     const _scope = _fileScope('bodyData');
 345     return new Promise((resolve, reject) => {
 346       const body = [];
 347       let length = 0;
 348       req.on('data', (chunk) => {
 349         body.push(chunk);
 350         length += Buffer.byteLength(chunk);
 351         if (maximumBodySize && length > maximumBodySize) {
 352           this.logger.debug(_scope, 'body data exceeded limit', { length, maximumBodySize });
 353           reject(new ResponseError(Enum.ErrorResponse.RequestEntityTooLarge));
 354         }
 355       });
 356       req.on('end', () => {
 357         const bodyBuffer = Buffer.concat(body);
 358         resolve(toString ? bodyBuffer.toString() : bodyBuffer);
 359       });
 360       req.on('error', (e) => {
 361         this.logger.error(_scope, 'failed', { error: e });
 362         reject(e);
 363       });
 364     });
 365   }
 366
 367
 368   /**
 369    * Read and parse request body data.
 370    * @param {http.ClientRequest} req
 371    * @param {http.ServerResponse} res
 372    * @param {object} ctx
 373    * @param {object}
 374    * @param {Boolean} .parseEmptyBody
 375    * @param {Boolean} .persistRawBody
 376    */
 377   async ingestBody(req, res, ctx, { parseEmptyBody = true, persistRawBody = false, maximumBodySize } = {}) {
 378     const rawBody = await this.bodyData(req, maximumBodySize);
 379     if (persistRawBody) {
 380       ctx.rawBody = rawBody;
 381     }
 382     if (rawBody || parseEmptyBody) {
 383       const contentType = Dingus.getRequestContentType(req);
 384       this.parseBody(contentType, ctx, rawBody);
 385     }
 386   }
 387
 388
 389   /**
 390    * Return the best matching response type.
 391    * @param {string[]} responseTypes
 392    * @param {http.ClientRequest} req
 393    */
 394   static getResponseContentType(responseTypes, req) {
 395     const acceptHeader = req.getHeader(Enum.Header.Accept);
 396     return ContentNegotiation.accept(responseTypes, acceptHeader);
 397   }
 398
 399
 400   /**
 401    * Returns a list of the most-preferred content encodings for the response.
 402    * @param {string[]} responseEncodings
 403    * @param {http.ClientRequest} req
 404    */
 405   static getResponseEncoding(responseEncodings, req) {
 406     const acceptEncodingHeader = req.getHeader(Enum.Header.AcceptEncoding);
 407     return ContentNegotiation.preferred(responseEncodings, acceptEncodingHeader);
 408   }
 409
 410
 411   /**
 412    * Set the best content type for the response.
 413    * @param {string[]} responseTypes default first
 414    * @param {http.ClientRequest} req
 415    * @param {http.ServerResponse} res
 416    * @param {object} ctx
 417    */
 418   setResponseType(responseTypes, req, res, ctx) {
 419     const _scope = _fileScope('setResponseType');
 420     ctx.responseType = Dingus.getResponseContentType(responseTypes, req);
 421     if (!ctx.responseType) {
 422       if (this.strictAccept) {
 423         this.logger.debug(_scope, 'unhandled strict accept', { requestId: req.requestId });
 424         throw new ResponseError(Enum.ErrorResponse.NotAcceptable);
 425       } else {
 426         ctx.responseType = responseTypes[0];
 427       }
 428     }
 429     res.setHeader(Enum.Header.ContentType, ctx.responseType);
 430   }
 431
 432
 433   /**
 434    * Inserts an encoding
 435    * @param {http.ServerResponse} res
 436    * @param {string} encoding
 437    */
 438   static addEncodingHeader(res, encoding) {
 439     const existingEncodings = res.getHeader(Enum.Header.ContentEncoding);
 440     if (existingEncodings) {
 441       encoding = `${encoding}, ${existingEncodings}`;
 442     }
 443     res.setHeader(Enum.Header.ContentEncoding, encoding);
 444   }
 445
 446
 447   /**
 448    * Attempt to fetch both data and metadata for a file.
 449    * @param {string} filePath
 450    */
 451   async _readFileInfo(filePath) {
 452     const _scope = _fileScope('_readFileInfo');
 453     let result;
 454     try {
 455       // eslint-disable-next-line security/detect-non-literal-fs-filename
 456       const stat = fsPromises.stat(filePath);
 457       // eslint-disable-next-line security/detect-non-literal-fs-filename
 458       const data = fsPromises.readFile(filePath);
 459       result = await Promise.all([stat, data]);
 460     } catch (e) {
 461       if (['ENOENT', 'EACCES', 'EISDIR', 'ENAMETOOLONG', 'EINVAL'].includes(e.code)) {
 462         return [null, null];
 463       }
 464       this.logger.error(_scope, 'fs error', { error: e, filePath });
 465       throw e;
 466     }
 467     return result;
 468   }
 469
 470
 471   /**
 472    * Potentially add additional headers from static file meta-file.
 473    * @param {http.ServerResponse} res
 474    * @param {string} directory
 475    * @param {string} fileName - already normalized and filtered
 476    */
 477   async _serveFileMetaHeaders(res, directory, fileName) {
 478     const _scope = _fileScope('_serveFileMetaHeaders');
 479     this.logger.debug(_scope, 'called', { directory, fileName });
 480
 481     const metaPrefix = '.';
 482     const metaSuffix = '.meta';
 483     const metaFileName = `${metaPrefix}${fileName}${metaSuffix}`;
 484     const metaFilePath = path.join(directory, metaFileName);
 485
 486     const [stat, data] = await this._readFileInfo(metaFilePath);
 487     if (!stat) {
 488       return;
 489     }
 490
 491     const lineBreakRE = /\r\n|\n|\r/;
 492     const lines = data.toString().split(lineBreakRE);
 493     common.unfoldHeaderLines(lines);
 494
 495     const headerParseRE = /^(?<name>[^:]+): +(?<value>.*)$/;
 496     lines.forEach((line) => {
 497       if (line) {
 498         const result = headerParseRE.exec(line);
 499         const { groups: header } = result;
 500         res.setHeader(header.name, header.value);
 501       }
 502     });
 503   }
 504
 505
 506   /**
 507    * Serve a file from a directory, with rudimentary cache awareness.
 508    * This will also serve pre-encoded variations if available and requested.
 509    * @param {http.ClientRequest} req
 510    * @param {http.ServerResponse} res
 511    * @param {object} ctx
 512    * @param {string} directory
 513    * @param {string} fileName
 514    */
 515   async serveFile(req, res, ctx, directory, fileName) {
 516     const _scope = _fileScope('serveFile');
 517     this.logger.debug(_scope, 'called', { req, ctx });
 518
 519     // Require a directory field.
 520     if (!directory) {
 521       this.logger.debug(_scope, 'rejected unset directory', { fileName });
 522       return this.handlerNotFound(req, res, ctx);
 523     }
 524
 525     // Normalize the supplied path, as encoded path-navigation may have been (maliciously) present.
 526     fileName = path.normalize(fileName);
 527
 528     // We will not deal with any subdirs, nor any dot-files.
 529     // (Note that we could not deal with subdirs even if we wanted, due to simple router matching scheme.)
 530     if (fileName.indexOf(path.sep) >= 0
 531     ||  fileName.startsWith('.')) {
 532       this.logger.debug(_scope, 'rejected filename', { fileName });
 533       return this.handlerNotFound(req, res, ctx);
 534     }
 535
 536     const filePath = path.join(directory, fileName);
 537
 538     // File must exist, before any alternate static encodings will be considered.
 539     let [stat, data] = await this._readFileInfo(filePath);
 540     if (!stat) {
 541       return this.handlerNotFound(req, res, ctx);
 542     }
 543
 544     // If encodings were requested, check for static versions to serve.
 545     // Update stat and data if matching version is found.
 546     ctx.availableEncodings = Dingus.getResponseEncoding(Object.values(Enum.EncodingType), req);
 547     if (ctx.availableEncodings.length === 0) {
 548       // Identity encoding was specifically denied, and nothing else available.
 549       this.logger.debug(_scope, 'no suitable encodings', { ctx });
 550       return this.handlerMethodNotAllowed(req, res, ctx);
 551     }
 552     for (const encoding of ctx.availableEncodings) {
 553       if (encoding === Enum.EncodingType.Identity) {
 554         break;
 555       }
 556       const suffix = Enum.EncodingTypeSuffix[encoding];
 557       if (!suffix) {
 558         this.logger.error(_scope, 'supported encoding missing mapped suffix', { ctx, encoding });
 559         continue;
 560       }
 561       const encodedFilePath = `${filePath}${suffix}`;
 562       const [ encodedStat, encodedData ] = await this._readFileInfo(encodedFilePath);
 563       if (encodedStat) {
 564         ([ stat, data ] = [ encodedStat, encodedData ]);
 565         ctx.selectedEncoding = encoding;
 566         Dingus.addEncodingHeader(res, encoding);
 567         res.setHeader(Enum.Header.Vary, Enum.Header.AcceptEncoding);
 568         this.logger.debug(_scope, 'serving encoded version', { ctx, encodedFilePath });
 569       }
 570       break;
 571     }
 572
 573     const lastModifiedDate = new Date(stat.mtimeMs);
 574     res.setHeader(Enum.Header.LastModified, lastModifiedDate.toGMTString());
 575
 576     const eTag = common.generateETag(filePath, stat, data);
 577     res.setHeader(Enum.Header.ETag, eTag);
 578
 579     if (common.isClientCached(req, stat.mtimeMs, eTag)) {
 580       this.logger.debug(_scope, 'client cached file', { filePath });
 581       res.statusCode = 304; // Not Modified
 582       res.end();
 583       return;
 584     }
 585
 586     // Set the type based on extension of un-encoded filename.
 587     const ext = path.extname(filePath).slice(1); // Drop the dot
 588     const contentType = extensionToMime(ext);
 589     res.setHeader(Enum.Header.ContentType, contentType);
 590
 591     // We presume static files are relatively cacheable.
 592     res.setHeader(Enum.Header.CacheControl, 'public');
 593
 594     if (this.staticMetadata) {
 595       await this._serveFileMetaHeaders(res, directory, fileName);
 596     }
 597
 598     this.logger.debug(_scope, 'serving file', { filePath, contentType });
 599     res.end(data);
 600   }
 601
 602
 603   /**
 604    * Return a content-type appropriate rendering of an errorResponse object.
 605    * @param {string} type content-type of response
 606    * @param {object} err either an Error object, or an error response
 607    * @param {number} err.statusCode
 608    * @param {string} err.errorMessage
 609    * @param {string|string[]} err.details
 610    */
 611   // eslint-disable-next-line class-methods-use-this
 612   renderError(contentType, err) {
 613     switch (contentType) {
 614       case Enum.ContentType.ApplicationJson:
 615         return JSON.stringify(err);
 616
 617       case Enum.ContentType.TextHTML:
 618         return Template.errorHTML(err);
 619
 620       case Enum.ContentType.TextPlain:
 621       default:
 622         return [err.errorMessage, err.details].join('\r\n');
 623     }
 624   }
 625
 626
 627   /**
 628    * Send an error response.  Terminal.
 629    * Logs any non-error-response errors as such.
 630    * @param {object} err either an Error object, or an error response
 631    * @param {http.ClientRequest} req
 632    * @param {http.ServerResponse} res
 633    * @param {object} ctx
 634    */
 635   sendErrorResponse(err, req, res, ctx) {
 636     const _scope = _fileScope('sendErrorResponse');
 637     let body;
 638
 639     // Default to a content type if one is not yet present
 640     if (!res.hasHeader(Enum.Header.ContentType)) {
 641       res.setHeader(Enum.Header.ContentType, Enum.ContentType.TextPlain);
 642     }
 643
 644     if (err?.statusCode) {
 645       res.statusCode = err.statusCode;
 646       body = this.renderError(res.getHeader(Enum.Header.ContentType), err);
 647       this.logger.debug(_scope, 'handler error', { err, req, res, ctx });
 648     } else {
 649       res.statusCode = 500;
 650       body = this.renderError(res.getHeader(Enum.Header.ContentType), Enum.ErrorResponse.InternalServerError);
 651       this.logger.error(_scope, 'handler exception', { err, req, res, ctx });
 652     }
 653     res.end(body);
 654   }
 655
 656
 657   /**
 658    * @param {http.ClientRequest} req
 659    * @param {http.ServerResponse} res
 660    * @param {object} ctx
 661    * @param {String} file - override ctx.params.file
 662    */
 663   async handlerGetStaticFile(req, res, ctx, file) {
 664     Dingus.setHeadHandler(req, res, ctx);
 665
 666     // Set a default response type to handle any errors; will be re-set to serve actual static content type.
 667     this.setResponseType(this.responseTypes, req, res, ctx);
 668
 669     await this.serveFile(req, res, ctx, this.staticPath, file || ctx.params.file);
 670   }
 671
 672
 673   /**
 674    * @param {http.ClientRequest} req
 675    * @param {http.ServerResponse} res
 676    * @param {Object} ctx
 677    * @param {String} newPath
 678    * @param {Number} statusCode
 679   */
 680   async handlerRedirect(req, res, ctx, newPath, statusCode = 307) {
 681     this.setResponseType(this.responseTypes, req, res, ctx);
 682     res.setHeader(Enum.Header.Location, newPath);
 683     res.statusCode = statusCode;
 684     res.end();
 685   }
 686
 687
 688   /**
 689    * @param {http.ClientRequest} req
 690    * @param {http.ServerResponse} res
 691    * @param {object} ctx
 692    */
 693   async handlerMethodNotAllowed(req, res, ctx) {
 694     this.setResponseType(this.responseTypes, req, res, ctx);
 695     throw new ResponseError(Enum.ErrorResponse.MethodNotAllowed);
 696   }
 697
 698
 699   /**
 700    * @param {http.ClientRequest} req
 701    * @param {http.ServerResponse} res
 702    * @param {object} ctx
 703    */
 704   async handlerNotFound(req, res, ctx) {
 705     this.setResponseType(this.responseTypes, req, res, ctx);
 706     throw new ResponseError(Enum.ErrorResponse.NotFound);
 707   }
 708
 709
 710   /**
 711    * @param {http.ClientRequest} req
 712    * @param {http.ServerResponse} res
 713    * @param {object} ctx
 714    */
 715   async handlerBadRequest(req, res, ctx) {
 716     this.setResponseType(this.responseTypes, req, res, ctx);
 717     throw new ResponseError(Enum.ErrorResponse.BadRequest);
 718   }
 719
 720
 721   /**
 722    * @param {http.ClientRequest} req
 723    * @param {http.ServerResponse} res
 724    * @param {object} ctx
 725    */
 726   async handlerInternalServerError(req, res, ctx) {
 727     this.setResponseType(this.responseTypes, req, res, ctx);
 728     throw new ResponseError(Enum.ErrorResponse.InternalServerError);
 729   }
 730
 731 }
 732
 733 module.exports = Dingus;