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 } = 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: false,
  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
  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 = common.nullLogger, 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     common.ensureLoggerLevels(this.logger);
  64   }
  65
  66
  67   /**
  68    * Resolve relative and empty paths in url
  69    * @param {string} p path
  70    */
  71   _normalizePath(p) {
  72     const pathNorm = path.normalize(p); // This isn't perfectly correct, but it's easy...
  73     return this._stripPrefix(pathNorm);
  74   }
  75
  76
  77   /**
  78    * Remove a leading portion of url path
  79    * N.B. This method gets obliterated if there is no prefix defined at construction
  80    * @param {string} p path
  81    */
  82   _stripPrefix(p) {
  83     if (p.startsWith(this.proxyPrefix)) {
  84       return p.slice(this.proxyPrefix.length);
  85     }
  86     return p;
  87   }
  88
  89
  90   /**
  91    * Returns the path part, and querystring object, from a request url.
  92    * @param {string} url
  93    */
  94   _splitUrl(url) {
  95     const [ p, qs ] = common.splitFirst(url, '?');
  96     return {
  97       pathPart: this._normalizePath(p),
  98       queryParams: this.querystring.parse(qs),
  99     };
 100   }
 101
 102
 103   /**
 104    * Insert a new path handler
 105    * @param {string} method
 106    * @param {string} urlPath
 107    * @param {fn} handler
 108    */
 109   on(method, urlPath, handler, ...handlerArgs) {
 110     this.router.on(method, urlPath, handler, handlerArgs);
 111   }
 112
 113
 114   /**
 115    * Common header tagging for all requests.
 116    * Add our own identifier, and persist any external transit identifiers.
 117    * @param {http.ClientRequest} req
 118    * @param {http.ServerResponse} res
 119    * @param {object} ctx
 120    */
 121   static tagContext(req, res, ctx) {
 122     const requestId = common.requestId();
 123     ctx.requestId = requestId;
 124     res.setHeader(Enum.Header.RequestId, requestId);
 125     [Enum.Header.XRequestId, Enum.Header.XCorrelationId].forEach((h) => {
 126       const v = req.getHeader(h);
 127       if (v) {
 128         ctx[h.replace(/-/g, '')] = v;
 129         res.setHeader(h, v);
 130       }
 131     });
 132     return requestId;
 133   }
 134
 135
 136   /**
 137    *
 138    * @param {http.ClientRequest} req
 139    */
 140   _getAddress(req) {
 141     // TODO: RFC7239 Forwarded support
 142     const address = (this.trustProxy && req && req.getHeader(Enum.Header.XForwardedFor)) ||
 143       (this.trustProxy && req && req.getHeader(Enum.Header.XRealIP)) ||
 144       (req && req.connection && req.connection.remoteAddress) ||
 145       '';
 146     return address.split(/\s*,\s*/u)[0];
 147   }
 148
 149
 150   /**
 151    *
 152    * @param {http.ClientRequest} req
 153    */
 154   _getProtocol(req) {
 155     // TODO: RFC7239 Forwarded support
 156     const protocol = (this.trustProxy && req && req.getHeader(Enum.Header.XForwardedProto)) ||
 157       ((req && req.connection && req.connection.encrypted) ? 'https' : 'http');
 158     return protocol.split(/\s*,\s*/u)[0];
 159   }
 160
 161
 162   /**
 163    *
 164    * @param {http.ClientRequest} req
 165    * @param {http.ServerResponse} res
 166    * @param {object} ctx
 167    */
 168   clientAddressContext(req, res, ctx) {
 169     ctx.clientAddress = this._getAddress(req);
 170     ctx.clientProtocol = this._getProtocol(req);
 171   }
 172
 173
 174   /**
 175    * Called before every request handler.
 176    * @param {http.ClientRequest} req
 177    * @param {http.ServerResponse} res
 178    * @param {object} ctx
 179    */
 180   async preHandler(req, res, ctx) {
 181     Dingus.tagContext(req, res, ctx);
 182     this.clientAddressContext(req, res, ctx);
 183   }
 184
 185
 186   /**
 187    * Helper for collecting chunks as array of buffers.
 188    * @param {Buffer[]} chunks
 189    * @param {string|Buffer} chunk
 190    * @param {string} encoding
 191    */
 192   static pushBufChunk(chunks, chunk, encoding = 'utf8') {
 193     if (chunk) {
 194       if (typeof chunk === 'string') {
 195         chunk = Buffer.from(chunk, encoding);
 196       }
 197       chunks.push(chunk);
 198     }
 199   }
 200
 201
 202   /**
 203    * Sets ctx.responseBody and calls handler upon res.end().
 204    * @param {http.ClientRequest} req
 205    * @param {http.ServerResponse} res
 206    * @param {object} ctx
 207    * @param {*} handler fn(req, res, ctx)
 208    */
 209   static setEndBodyHandler(req, res, ctx, handler) {
 210     const origWrite = res.write.bind(res);
 211     const origEnd = res.end.bind(res);
 212     const chunks = [];
 213     res.write = function (chunk, encoding, ...rest) {
 214       Dingus.pushBufChunk(chunks, chunk, encoding);
 215       return origWrite(chunk, encoding, ...rest);
 216     };
 217     res.end = function (data, encoding, ...rest) {
 218       Dingus.pushBufChunk(chunks, data, encoding);
 219       ctx.responseBody = Buffer.concat(chunks);
 220       handler(req, res, ctx);
 221       return origEnd(data, encoding, ...rest);
 222     };
 223   }
 224
 225
 226   /**
 227    * Intercept writes for head requests, do not send to client,
 228    * but send length, and make body available in context.
 229    * N.B. If persisted, ctx.responseBody will be a raw buffer, be aware when logging.
 230    * @param {http.ClientRequest} req
 231    * @param {http.ServerResponse} res
 232    * @param {object} ctx
 233    * @param {Boolean} persistResponseBody
 234    */
 235   static setHeadHandler(req, res, ctx, persistResponseBody = false) {
 236     if (req.method === 'HEAD') {
 237       const origEnd = res.end.bind(res);
 238       const chunks = [];
 239       res.write = function (chunk, encoding) {
 240         Dingus.pushBufChunk(chunks, chunk, encoding);
 241         // No call to original res.write.
 242       };
 243       res.end = function (data, encoding, ...rest) {
 244         Dingus.pushBufChunk(chunks, data, encoding);
 245         const responseBody = Buffer.concat(chunks);
 246         res.setHeader(Enum.Header.ContentLength, Buffer.byteLength(responseBody));
 247         if (persistResponseBody) {
 248           ctx.responseBody = responseBody;
 249         }
 250         return origEnd(undefined, encoding, ...rest);
 251       };
 252     }
 253   }
 254
 255
 256   /**
 257    * Dispatch the handler for a request
 258    * @param {http.ClientRequest} req
 259    * @param {http.ServerResponse} res
 260    * @param {object} ctx
 261    */
 262   async dispatch(req, res, ctx = {}) {
 263     const _scope = _fileScope('dispatch');
 264
 265     const { pathPart, queryParams } = this._splitUrl(req.url);
 266     ctx.queryParams = queryParams;
 267
 268     let handler, handlerArgs = [];
 269     try {
 270       ({ handler, handlerArgs } = this.router.lookup(req.method, pathPart, ctx));
 271     } catch (e) {
 272       if (e instanceof DingusError) {
 273         switch (e.message) {
 274           case 'NoPath':
 275             handler = this.handlerNotFound.bind(this);
 276             break;
 277           case 'NoMethod':
 278             handler = this.handlerMethodNotAllowed.bind(this);
 279             break;
 280           default:
 281             this.logger.error(_scope, 'unknown dingus error', { error: e });
 282             handler = this.handlerInternalServerError.bind(this);
 283         }
 284       } else if (e instanceof URIError) {
 285         handler = this.handlerBadRequest.bind(this);
 286       } else {
 287         this.logger.error(_scope, 'lookup failure', { error: e });
 288         handler = this.handlerInternalServerError.bind(this);
 289       }
 290     }
 291
 292     try {
 293       await this.preHandler(req, res, ctx);
 294       return await handler(req, res, ctx, ...handlerArgs);
 295     } catch (e) {
 296       ctx.error = e;
 297       this.sendErrorResponse(e, req, res, ctx);
 298     }
 299   }
 300
 301
 302   /**
 303    * Return normalized type, without any parameters.
 304    * @param {http.ClientRequest} req
 305    * @returns {string}
 306    */
 307   static getRequestContentType(req) {
 308     const contentType = req.getHeader(Enum.Header.ContentType);
 309     return (contentType || '').split(';')[0].trim().toLowerCase();
 310   }
 311
 312
 313   /**
 314    * Parse rawBody as contentType into ctx.parsedBody.
 315    * @param {string} contentType
 316    * @param {object} ctx
 317    * @param {string|buffer}
 318   */
 319   parseBody(contentType, ctx, rawBody) {
 320     const _scope = _fileScope('parseBody');
 321
 322     if (!rawBody) {
 323       // 1.2.4 and earlier expected rawBody on context
 324       rawBody = ctx.rawBody;
 325     }
 326
 327     switch (contentType) {
 328       case Enum.ContentType.ApplicationForm:
 329         ctx.parsedBody = this.querystring.parse(rawBody);
 330         break;
 331
 332       case Enum.ContentType.ApplicationJson:
 333         try {
 334           ctx.parsedBody = JSON.parse(rawBody);
 335         } catch (e) {
 336           this.logger.debug(_scope, 'JSON parse failed', { requestId: ctx.requestId, error: e });
 337           throw new ResponseError(Enum.ErrorResponse.BadRequest, e.message);
 338         }
 339         break;
 340
 341       default:
 342         this.logger.debug(_scope, 'unhandled content-type', { requestId: ctx.requestId, contentType });
 343         throw new ResponseError(Enum.ErrorResponse.UnsupportedMediaType);
 344     }
 345   }
 346
 347
 348   /**
 349    * Return all body data from a request.
 350    * @param {http.ClientRequest} req
 351    * @param {Number=} maximumBodySize
 352    */
 353   async bodyData(req, maximumBodySize) {
 354     const _scope = _fileScope('bodyData');
 355     return new Promise((resolve, reject) => {
 356       const body = [];
 357       let length = 0;
 358       req.on('data', (chunk) => {
 359         body.push(chunk);
 360         length += Buffer.byteLength(chunk);
 361         if (maximumBodySize && length > maximumBodySize) {
 362           this.logger.debug(_scope, 'body data exceeded limit', { length, maximumBodySize });
 363           reject(new ResponseError(Enum.ErrorResponse.RequestEntityTooLarge));
 364         }
 365       });
 366       req.on('end', () => resolve(Buffer.concat(body).toString()));
 367       req.on('error', (e) => {
 368         this.logger.error(_scope, 'failed', { error: e });
 369         reject(e);
 370       });
 371     });
 372   }
 373
 374
 375   /**
 376    * Read and parse request body data.
 377    * @param {http.ClientRequest} req
 378    * @param {http.ServerResponse} res
 379    * @param {object} ctx
 380    * @param {object}
 381    * @param {Boolean} .parseEmptyBody
 382    * @param {Boolean} .persistRawBody
 383    */
 384   async ingestBody(req, res, ctx, { parseEmptyBody = true, persistRawBody = false, maximumBodySize } = {}) {
 385     const rawBody = await this.bodyData(req, maximumBodySize);
 386     if (persistRawBody) {
 387       ctx.rawBody = rawBody;
 388     }
 389     if (rawBody || parseEmptyBody) {
 390       const contentType = Dingus.getRequestContentType(req);
 391       this.parseBody(contentType, ctx, rawBody);
 392     }
 393   }
 394
 395
 396   /**
 397    * Return the best matching response type.
 398    * @param {string[]} responseTypes
 399    * @param {http.ClientRequest} req
 400    */
 401   static getResponseContentType(responseTypes, req) {
 402     const acceptHeader = req.getHeader(Enum.Header.Accept);
 403     return ContentNegotiation.accept(responseTypes, acceptHeader);
 404   }
 405
 406
 407   /**
 408    * Returns a list of the most-preferred content encodings for the response.
 409    * @param {string[]} responseEncodings
 410    * @param {http.ClientRequest} req
 411    */
 412   static getResponseEncoding(responseEncodings, req) {
 413     const acceptEncodingHeader = req.getHeader(Enum.Header.AcceptEncoding);
 414     return ContentNegotiation.preferred(responseEncodings, acceptEncodingHeader);
 415   }
 416
 417
 418   /**
 419    * Set the best content type for the response.
 420    * @param {string[]} responseTypes default first
 421    * @param {http.ClientRequest} req
 422    * @param {http.ServerResponse} res
 423    * @param {object} ctx
 424    */
 425   setResponseType(responseTypes, req, res, ctx) {
 426     const _scope = _fileScope('setResponseType');
 427     ctx.responseType = Dingus.getResponseContentType(responseTypes, req);
 428     if (!ctx.responseType) {
 429       if (this.strictAccept) {
 430         this.logger.debug(_scope, 'unhandled strict accept', { requestId: req.requestId });
 431         throw new ResponseError(Enum.ErrorResponse.NotAcceptable);
 432       } else {
 433         ctx.responseType = responseTypes[0];
 434       }
 435     }
 436     res.setHeader(Enum.Header.ContentType, ctx.responseType);
 437   }
 438
 439
 440   /**
 441    * Inserts an encoding
 442    * @param {http.ServerResponse} res
 443    * @param {string} encoding
 444    */
 445   static addEncodingHeader(res, encoding) {
 446     const existingEncodings = res.getHeader(Enum.Header.ContentEncoding);
 447     if (existingEncodings) {
 448       encoding = `${encoding}, ${existingEncodings}`;
 449     }
 450     res.setHeader(Enum.Header.ContentEncoding, encoding);
 451   }
 452
 453
 454   /**
 455    * Attempt to fetch both data and metadata for a file.
 456    * @param {string} filePath
 457    */
 458   async _readFileInfo(filePath) {
 459     const _scope = _fileScope('_readFileInfo');
 460     let result;
 461     try {
 462       // eslint-disable-next-line security/detect-non-literal-fs-filename
 463       const stat = fsPromises.stat(filePath);
 464       // eslint-disable-next-line security/detect-non-literal-fs-filename
 465       const data = fsPromises.readFile(filePath);
 466       result = await Promise.all([stat, data]);
 467     } catch (e) {
 468       if (['ENOENT', 'EACCES', 'EISDIR', 'ENAMETOOLONG', 'EINVAL'].includes(e.code)) {
 469         return [null, null];
 470       }
 471       this.logger.error(_scope, 'fs error', { error: e, filePath });
 472       throw e;
 473     }
 474     return result;
 475   }
 476
 477
 478   /**
 479    * Potentially add additional headers from static file meta-file.
 480    * @param {http.ServerResponse} res
 481    * @param {string} directory
 482    * @param {string} fileName - already normalized and filtered
 483    */
 484   async _serveFileMetaHeaders(res, directory, fileName) {
 485     const _scope = _fileScope('_serveFileMetaHeaders');
 486     this.logger.debug(_scope, 'called', { directory, fileName });
 487
 488     const metaPrefix = '.';
 489     const metaSuffix = '.meta';
 490     const metaFileName = `${metaPrefix}${fileName}${metaSuffix}`;
 491     const metaFilePath = path.join(directory, metaFileName);
 492
 493     const [stat, data] = await this._readFileInfo(metaFilePath);
 494     if (!stat) {
 495       return;
 496     }
 497
 498     const lineBreakRE = /\r\n|\n|\r/;
 499     const lines = data.toString().split(lineBreakRE);
 500     common.unfoldHeaderLines(lines);
 501
 502     const headerParseRE = /^(?<name>[^:]+): +(?<value>.*)$/;
 503     lines.forEach((line) => {
 504       if (line) {
 505         const result = headerParseRE.exec(line);
 506         const { groups: header } = result;
 507         res.setHeader(header.name, header.value);
 508       }
 509     });
 510   }
 511
 512
 513   /**
 514    * Serve a file from a directory, with rudimentary cache awareness.
 515    * This will also serve pre-encoded variations if available and requested.
 516    * @param {http.ClientRequest} req
 517    * @param {http.ServerResponse} res
 518    * @param {object} ctx
 519    * @param {string} directory
 520    * @param {string} fileName
 521    */
 522   async serveFile(req, res, ctx, directory, fileName) {
 523     const _scope = _fileScope('serveFile');
 524     this.logger.debug(_scope, 'called', { req: common.requestLogData(req), ctx });
 525
 526     // Require a directory field.
 527     if (!directory) {
 528       this.logger.debug(_scope, 'rejected unset directory', { fileName });
 529       return this.handlerNotFound(req, res, ctx);
 530     }
 531
 532     // Normalize the supplied path, as encoded path-navigation may have been (maliciously) present.
 533     fileName = path.normalize(fileName);
 534
 535     // We will not deal with any subdirs, nor any dot-files.
 536     // (Note that we could not deal with subdirs even if we wanted, due to simple router matching scheme.)
 537     if (fileName.indexOf(path.sep) >= 0
 538     ||  fileName.charAt(0) === '.') {
 539       this.logger.debug(_scope, 'rejected filename', { fileName });
 540       return this.handlerNotFound(req, res, ctx);
 541     }
 542
 543     const filePath = path.join(directory, fileName);
 544
 545     // File must exist, before any alternate static encodings will be considered.
 546     let [stat, data] = await this._readFileInfo(filePath);
 547     if (!stat) {
 548       return this.handlerNotFound(req, res, ctx);
 549     }
 550
 551     // If encodings were requested, check for static versions to serve.
 552     // Update stat and data if matching version is found.
 553     ctx.availableEncodings = Dingus.getResponseEncoding(Object.values(Enum.EncodingType), req);
 554     if (ctx.availableEncodings.length === 0) {
 555       // Identity encoding was specifically denied, and nothing else available.
 556       this.logger.debug(_scope, 'no suitable encodings', { ctx });
 557       return this.handlerMethodNotAllowed(req, res, ctx);
 558     }
 559     for (const encoding of ctx.availableEncodings) {
 560       if (encoding === Enum.EncodingType.Identity) {
 561         break;
 562       }
 563       const suffix = Enum.EncodingTypeSuffix[encoding];
 564       if (suffix) {
 565         const encodedFilePath = `${filePath}${suffix}`;
 566         const [ encodedStat, encodedData ] = await this._readFileInfo(encodedFilePath);
 567         if (encodedStat) {
 568           ([ stat, data ] = [ encodedStat, encodedData ]);
 569           ctx.selectedEncoding = encoding;
 570           Dingus.addEncodingHeader(res, encoding);
 571           res.setHeader(Enum.Header.Vary, Enum.Header.AcceptEncoding);
 572           this.logger.debug(_scope, 'serving encoded version', { ctx, encodedFilePath });
 573         }
 574         break;
 575       }
 576     }
 577
 578     const lastModifiedDate = new Date(stat.mtimeMs);
 579     res.setHeader(Enum.Header.LastModified, lastModifiedDate.toGMTString());
 580
 581     const eTag = common.generateETag(filePath, stat, data);
 582     res.setHeader(Enum.Header.ETag, eTag);
 583
 584     if (common.isClientCached(req, stat.mtimeMs, eTag)) {
 585       this.logger.debug(_scope, 'client cached file', { filePath });
 586       res.statusCode = 304; // Not Modified
 587       res.end();
 588       return;
 589     }
 590
 591     // Set the type based on extension of un-encoded filename.
 592     const ext = path.extname(filePath).slice(1); // Drop the dot
 593     const contentType = extensionToMime(ext);
 594     res.setHeader(Enum.Header.ContentType, contentType);
 595
 596     // We presume static files are relatively cacheable.
 597     res.setHeader(Enum.Header.CacheControl, 'public');
 598
 599     if (this.staticMetadata) {
 600       await this._serveFileMetaHeaders(res, directory, fileName);
 601     }
 602
 603     this.logger.debug(_scope, 'serving file', { filePath, contentType });
 604     res.end(data);
 605   }
 606
 607
 608   /**
 609    * Return a content-type appropriate rendering of an errorResponse object.
 610    * @param {string} type content-type of response
 611    * @param {object} err either an Error object, or an error response
 612    * @param {number} err.statusCode
 613    * @param {string} err.errorMessage
 614    * @param {string|string[]} err.details
 615    */
 616   // eslint-disable-next-line class-methods-use-this
 617   renderError(contentType, err) {
 618     switch (contentType) {
 619       case Enum.ContentType.ApplicationJson:
 620         return JSON.stringify(err);
 621
 622       case Enum.ContentType.TextHTML:
 623         return Template.errorHTML(err);
 624
 625       case Enum.ContentType.TextPlain:
 626       default:
 627         return [err.errorMessage, err.details].join('\r\n');
 628     }
 629   }
 630
 631
 632   /**
 633    * Send an error response.  Terminal.
 634    * Logs any non-error-response errors as such.
 635    * @param {object} err either an Error object, or an error response
 636    * @param {http.ClientRequest} req
 637    * @param {http.ServerResponse} res
 638    * @param {object} ctx
 639    */
 640   sendErrorResponse(err, req, res, ctx) {
 641     const _scope = _fileScope('sendErrorResponse');
 642     let body;
 643
 644     // Default to a content type if one is not yet present
 645     if (!res.hasHeader(Enum.Header.ContentType)) {
 646       res.setHeader(Enum.Header.ContentType, Enum.ContentType.TextPlain);
 647     }
 648
 649     if (err && err.statusCode) {
 650       res.statusCode = err.statusCode;
 651       body = this.renderError(res.getHeader(Enum.Header.ContentType), err);
 652       this.logger.debug(_scope, 'handler error', { err, ...common.handlerLogData(req, res, ctx) });
 653     } else {
 654       res.statusCode = 500;
 655       body = this.renderError(res.getHeader(Enum.Header.ContentType), Enum.ErrorResponse.InternalServerError);
 656       this.logger.error(_scope, 'handler exception', { err, ...common.handlerLogData(req, res, ctx) });
 657     }
 658     res.end(body);
 659   }
 660
 661
 662   /**
 663    * @param {http.ClientRequest} req
 664    * @param {http.ServerResponse} res
 665    * @param {object} ctx
 666    * @param {String} file - override ctx.params.file
 667    */
 668   async handlerGetStaticFile(req, res, ctx, file) {
 669     Dingus.setHeadHandler(req, res, ctx);
 670
 671     // Set a default response type to handle any errors; will be re-set to serve actual static content type.
 672     this.setResponseType(this.responseTypes, req, res, ctx);
 673
 674     await this.serveFile(req, res, ctx, this.staticPath, file || ctx.params.file);
 675   }
 676
 677
 678   /**
 679    * @param {http.ClientRequest} req
 680    * @param {http.ServerResponse} res
 681    * @param {Object} ctx
 682    * @param {String} newPath
 683    * @param {Number} statusCode
 684   */
 685   async handlerRedirect(req, res, ctx, newPath, statusCode = 307) {
 686     this.setResponseType(this.responseTypes, req, res, ctx);
 687     res.setHeader(Enum.Header.Location, newPath);
 688     res.statusCode = statusCode;
 689     res.end();
 690   }
 691
 692
 693   /**
 694    * @param {http.ClientRequest} req
 695    * @param {http.ServerResponse} res
 696    * @param {object} ctx
 697    */
 698   async handlerMethodNotAllowed(req, res, ctx) {
 699     this.setResponseType(this.responseTypes, req, res, ctx);
 700     throw new ResponseError(Enum.ErrorResponse.MethodNotAllowed);
 701   }
 702
 703
 704   /**
 705    * @param {http.ClientRequest} req
 706    * @param {http.ServerResponse} res
 707    * @param {object} ctx
 708    */
 709   async handlerNotFound(req, res, ctx) {
 710     this.setResponseType(this.responseTypes, req, res, ctx);
 711     throw new ResponseError(Enum.ErrorResponse.NotFound);
 712   }
 713
 714
 715   /**
 716    * @param {http.ClientRequest} req
 717    * @param {http.ServerResponse} res
 718    * @param {object} ctx
 719    */
 720   async handlerBadRequest(req, res, ctx) {
 721     this.setResponseType(this.responseTypes, req, res, ctx);
 722     throw new ResponseError(Enum.ErrorResponse.BadRequest);
 723   }
 724
 725
 726   /**
 727    * @param {http.ClientRequest} req
 728    * @param {http.ServerResponse} res
 729    * @param {object} ctx
 730    */
 731   async handlerInternalServerError(req, res, ctx) {
 732     this.setResponseType(this.responseTypes, req, res, ctx);
 733     throw new ResponseError(Enum.ErrorResponse.InternalServerError);
 734   }
 735
 736 }
 737
 738 module.exports = Dingus;