/*!
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* finalhandler
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* Copyright(c) 2014-2022 Douglas Christopher Wilson
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* MIT Licensed
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*/
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'use strict'
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/**
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* Module dependencies.
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* @private
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*/
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var debug = require('debug')('finalhandler')
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var encodeUrl = require('encodeurl')
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var escapeHtml = require('escape-html')
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var onFinished = require('on-finished')
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var parseUrl = require('parseurl')
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var statuses = require('statuses')
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var unpipe = require('unpipe')
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/**
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* Module variables.
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* @private
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*/
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var DOUBLE_SPACE_REGEXP = /\x20{2}/g
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var NEWLINE_REGEXP = /\n/g
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/* istanbul ignore next */
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var defer = typeof setImmediate === 'function'
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? setImmediate
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: function (fn) { process.nextTick(fn.bind.apply(fn, arguments)) }
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var isFinished = onFinished.isFinished
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/**
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* Create a minimal HTML document.
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*
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* @param {string} message
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* @private
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*/
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function createHtmlDocument (message) {
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var body = escapeHtml(message)
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.replace(NEWLINE_REGEXP, '<br>')
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.replace(DOUBLE_SPACE_REGEXP, ' ')
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return '<!DOCTYPE html>\n' +
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'<html lang="en">\n' +
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'<head>\n' +
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'<meta charset="utf-8">\n' +
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'<title>Error</title>\n' +
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'</head>\n' +
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'<body>\n' +
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'<pre>' + body + '</pre>\n' +
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'</body>\n' +
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'</html>\n'
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}
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/**
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* Module exports.
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* @public
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*/
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module.exports = finalhandler
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/**
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* Create a function to handle the final response.
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*
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* @param {Request} req
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* @param {Response} res
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* @param {Object} [options]
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* @return {Function}
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* @public
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*/
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function finalhandler (req, res, options) {
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var opts = options || {}
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// get environment
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var env = opts.env || process.env.NODE_ENV || 'development'
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// get error callback
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var onerror = opts.onerror
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return function (err) {
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var headers
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var msg
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var status
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// ignore 404 on in-flight response
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if (!err && headersSent(res)) {
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debug('cannot 404 after headers sent')
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return
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}
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// unhandled error
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if (err) {
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// respect status code from error
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status = getErrorStatusCode(err)
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if (status === undefined) {
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// fallback to status code on response
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status = getResponseStatusCode(res)
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} else {
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// respect headers from error
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headers = getErrorHeaders(err)
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}
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// get error message
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msg = getErrorMessage(err, status, env)
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} else {
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// not found
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status = 404
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msg = 'Cannot ' + req.method + ' ' + encodeUrl(getResourceName(req))
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}
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debug('default %s', status)
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// schedule onerror callback
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if (err && onerror) {
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defer(onerror, err, req, res)
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}
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// cannot actually respond
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if (headersSent(res)) {
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debug('cannot %d after headers sent', status)
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req.socket.destroy()
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return
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}
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// send response
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send(req, res, status, headers, msg)
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}
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}
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/**
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* Get headers from Error object.
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*
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* @param {Error} err
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* @return {object}
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* @private
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*/
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function getErrorHeaders (err) {
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if (!err.headers || typeof err.headers !== 'object') {
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return undefined
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}
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var headers = Object.create(null)
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var keys = Object.keys(err.headers)
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for (var i = 0; i < keys.length; i++) {
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var key = keys[i]
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headers[key] = err.headers[key]
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}
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return headers
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}
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/**
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* Get message from Error object, fallback to status message.
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*
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* @param {Error} err
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* @param {number} status
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* @param {string} env
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* @return {string}
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* @private
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*/
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function getErrorMessage (err, status, env) {
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var msg
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if (env !== 'production') {
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// use err.stack, which typically includes err.message
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msg = err.stack
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// fallback to err.toString() when possible
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if (!msg && typeof err.toString === 'function') {
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msg = err.toString()
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}
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}
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return msg || statuses.message[status]
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}
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/**
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* Get status code from Error object.
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*
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* @param {Error} err
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* @return {number}
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* @private
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*/
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function getErrorStatusCode (err) {
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// check err.status
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if (typeof err.status === 'number' && err.status >= 400 && err.status < 600) {
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return err.status
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}
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// check err.statusCode
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if (typeof err.statusCode === 'number' && err.statusCode >= 400 && err.statusCode < 600) {
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return err.statusCode
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}
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return undefined
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}
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/**
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* Get resource name for the request.
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*
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* This is typically just the original pathname of the request
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* but will fallback to "resource" is that cannot be determined.
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*
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* @param {IncomingMessage} req
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* @return {string}
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* @private
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*/
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function getResourceName (req) {
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try {
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return parseUrl.original(req).pathname
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} catch (e) {
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return 'resource'
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}
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}
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/**
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* Get status code from response.
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*
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* @param {OutgoingMessage} res
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* @return {number}
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* @private
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*/
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function getResponseStatusCode (res) {
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var status = res.statusCode
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// default status code to 500 if outside valid range
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if (typeof status !== 'number' || status < 400 || status > 599) {
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status = 500
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}
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return status
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}
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/**
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* Determine if the response headers have been sent.
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*
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* @param {object} res
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* @returns {boolean}
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* @private
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*/
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function headersSent (res) {
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return typeof res.headersSent !== 'boolean'
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? Boolean(res._header)
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: res.headersSent
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}
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/**
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* Send response.
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*
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* @param {IncomingMessage} req
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* @param {OutgoingMessage} res
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* @param {number} status
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* @param {object} headers
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* @param {string} message
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* @private
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*/
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function send (req, res, status, headers, message) {
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function write () {
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// response body
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var body = createHtmlDocument(message)
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// response status
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res.statusCode = status
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res.statusMessage = statuses.message[status]
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// remove any content headers
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res.removeHeader('Content-Encoding')
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res.removeHeader('Content-Language')
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res.removeHeader('Content-Range')
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// response headers
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setHeaders(res, headers)
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// security headers
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res.setHeader('Content-Security-Policy', "default-src 'none'")
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res.setHeader('X-Content-Type-Options', 'nosniff')
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// standard headers
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res.setHeader('Content-Type', 'text/html; charset=utf-8')
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res.setHeader('Content-Length', Buffer.byteLength(body, 'utf8'))
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if (req.method === 'HEAD') {
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res.end()
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return
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}
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res.end(body, 'utf8')
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}
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if (isFinished(req)) {
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write()
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return
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}
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// unpipe everything from the request
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unpipe(req)
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// flush the request
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onFinished(req, write)
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req.resume()
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}
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/**
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* Set response headers from an object.
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*
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* @param {OutgoingMessage} res
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* @param {object} headers
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* @private
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*/
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function setHeaders (res, headers) {
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if (!headers) {
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return
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}
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var keys = Object.keys(headers)
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for (var i = 0; i < keys.length; i++) {
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var key = keys[i]
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res.setHeader(key, headers[key])
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}
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}
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