Spaces:
Running
Running
File size: 2,705 Bytes
1719261 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 |
/*!
* fresh
* Copyright(c) 2012 TJ Holowaychuk
* Copyright(c) 2016-2017 Douglas Christopher Wilson
* MIT Licensed
*/
'use strict'
/**
* RegExp to check for no-cache token in Cache-Control.
* @private
*/
var CACHE_CONTROL_NO_CACHE_REGEXP = /(?:^|,)\s*?no-cache\s*?(?:,|$)/
/**
* Module exports.
* @public
*/
module.exports = fresh
/**
* Check freshness of the response using request and response headers.
*
* @param {Object} reqHeaders
* @param {Object} resHeaders
* @return {Boolean}
* @public
*/
function fresh (reqHeaders, resHeaders) {
// fields
var modifiedSince = reqHeaders['if-modified-since']
var noneMatch = reqHeaders['if-none-match']
// unconditional request
if (!modifiedSince && !noneMatch) {
return false
}
// Always return stale when Cache-Control: no-cache
// to support end-to-end reload requests
// https://tools.ietf.org/html/rfc2616#section-14.9.4
var cacheControl = reqHeaders['cache-control']
if (cacheControl && CACHE_CONTROL_NO_CACHE_REGEXP.test(cacheControl)) {
return false
}
// if-none-match takes precedent over if-modified-since
if (noneMatch) {
if (noneMatch === '*') {
return true
}
var etag = resHeaders.etag
if (!etag) {
return false
}
var matches = parseTokenList(noneMatch)
for (var i = 0; i < matches.length; i++) {
var match = matches[i]
if (match === etag || match === 'W/' + etag || 'W/' + match === etag) {
return true
}
}
return false
}
// if-modified-since
if (modifiedSince) {
var lastModified = resHeaders['last-modified']
var modifiedStale = !lastModified || !(parseHttpDate(lastModified) <= parseHttpDate(modifiedSince))
if (modifiedStale) {
return false
}
}
return true
}
/**
* Parse an HTTP Date into a number.
*
* @param {string} date
* @private
*/
function parseHttpDate (date) {
var timestamp = date && Date.parse(date)
// istanbul ignore next: guard against date.js Date.parse patching
return typeof timestamp === 'number'
? timestamp
: NaN
}
/**
* Parse a HTTP token list.
*
* @param {string} str
* @private
*/
function parseTokenList (str) {
var end = 0
var list = []
var start = 0
// gather tokens
for (var i = 0, len = str.length; i < len; i++) {
switch (str.charCodeAt(i)) {
case 0x20: /* */
if (start === end) {
start = end = i + 1
}
break
case 0x2c: /* , */
list.push(str.substring(start, end))
start = end = i + 1
break
default:
end = i + 1
break
}
}
// final token
list.push(str.substring(start, end))
return list
}
|