root / HServer / 00.Server / 00.Program / node_modules / fresh / index.js
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| 1 | 39 | HKM | /*!
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| 2 | * fresh
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| 3 | * Copyright(c) 2012 TJ Holowaychuk
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| 4 | * Copyright(c) 2016-2017 Douglas Christopher Wilson
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| 5 | * MIT Licensed
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| 6 | */
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| 7 | |||
| 8 | 'use strict'
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| 9 | |||
| 10 | /**
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| 11 | * RegExp to check for no-cache token in Cache-Control.
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| 12 | * @private
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| 13 | */
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| 14 | |||
| 15 | var CACHE_CONTROL_NO_CACHE_REGEXP = /(?:^|,)\s*?no-cache\s*?(?:,|$)/ |
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| 16 | |||
| 17 | /**
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| 18 | * Module exports.
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| 19 | * @public
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| 20 | */
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| 21 | |||
| 22 | module.exports = fresh |
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| 23 | |||
| 24 | /**
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| 25 | * Check freshness of the response using request and response headers.
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| 26 | *
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| 27 | * @param {Object} reqHeaders
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| 28 | * @param {Object} resHeaders
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| 29 | * @return {Boolean}
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| 30 | * @public
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| 31 | */
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| 32 | |||
| 33 | function fresh (reqHeaders, resHeaders) { |
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| 34 | // fields
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| 35 | var modifiedSince = reqHeaders['if-modified-since'] |
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| 36 | var noneMatch = reqHeaders['if-none-match'] |
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| 37 | |||
| 38 | // unconditional request
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| 39 | if (!modifiedSince && !noneMatch) {
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| 40 | return false |
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| 41 | } |
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| 42 | |||
| 43 | // Always return stale when Cache-Control: no-cache
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| 44 | // to support end-to-end reload requests
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| 45 | // https://tools.ietf.org/html/rfc2616#section-14.9.4
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| 46 | var cacheControl = reqHeaders['cache-control'] |
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| 47 | if (cacheControl && CACHE_CONTROL_NO_CACHE_REGEXP.test(cacheControl)) {
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| 48 | return false |
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| 49 | } |
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| 50 | |||
| 51 | // if-none-match
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| 52 | if (noneMatch && noneMatch !== '*') { |
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| 53 | var etag = resHeaders['etag'] |
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| 54 | |||
| 55 | if (!etag) {
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| 56 | return false |
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| 57 | } |
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| 58 | |||
| 59 | var etagStale = true |
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| 60 | var matches = parseTokenList(noneMatch)
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| 61 | for (var i = 0; i < matches.length; i++) { |
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| 62 | var match = matches[i]
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| 63 | if (match === etag || match === 'W/' + etag || 'W/' + match === etag) { |
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| 64 | etagStale = false
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| 65 | break
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| 66 | } |
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| 67 | } |
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| 68 | |||
| 69 | if (etagStale) {
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| 70 | return false |
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| 71 | } |
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| 72 | } |
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| 73 | |||
| 74 | // if-modified-since
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| 75 | if (modifiedSince) {
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| 76 | var lastModified = resHeaders['last-modified'] |
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| 77 | var modifiedStale = !lastModified || !(parseHttpDate(lastModified) <= parseHttpDate(modifiedSince))
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| 78 | |||
| 79 | if (modifiedStale) {
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| 80 | return false |
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| 81 | } |
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| 82 | } |
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| 83 | |||
| 84 | return true |
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| 85 | } |
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| 86 | |||
| 87 | /**
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| 88 | * Parse an HTTP Date into a number.
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| 89 | *
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| 90 | * @param {string} date
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| 91 | * @private
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| 92 | */
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| 93 | |||
| 94 | function parseHttpDate (date) { |
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| 95 | var timestamp = date && Date.parse(date)
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| 96 | |||
| 97 | // istanbul ignore next: guard against date.js Date.parse patching
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| 98 | return typeof timestamp === 'number' |
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| 99 | ? timestamp |
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| 100 | : NaN
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| 101 | } |
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| 102 | |||
| 103 | /**
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| 104 | * Parse a HTTP token list.
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| 105 | *
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| 106 | * @param {string} str
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| 107 | * @private
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| 108 | */
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| 109 | |||
| 110 | function parseTokenList (str) { |
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| 111 | var end = 0 |
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| 112 | var list = []
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| 113 | var start = 0 |
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| 114 | |||
| 115 | // gather tokens
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| 116 | for (var i = 0, len = str.length; i < len; i++) { |
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| 117 | switch (str.charCodeAt(i)) {
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| 118 | case 0x20: /* */ |
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| 119 | if (start === end) {
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| 120 | start = end = i + 1
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| 121 | } |
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| 122 | break
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| 123 | case 0x2c: /* , */ |
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| 124 | list.push(str.substring(start, end)) |
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| 125 | start = end = i + 1
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| 126 | break
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| 127 | default:
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| 128 | end = i + 1
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| 129 | break
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| 130 | } |
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| 131 | } |
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| 132 | |||
| 133 | // final token
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| 134 | list.push(str.substring(start, end)) |
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| 135 | |||
| 136 | return list
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| 137 | } |