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vary.js
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vary.js
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'use strict'
const LRUCache = require('mnemonist/lru-cache')
/**
* Field Value Components
* Most HTTP header field values are defined using common syntax
* components (token, quoted-string, and comment) separated by
* whitespace or specific delimiting characters. Delimiters are chosen
* from the set of US-ASCII visual characters not allowed in a token
* (DQUOTE and "(),/:;<=>?@[\]{}").
*
* field-name = token
* token = 1*tchar
* tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*"
* / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"
* / DIGIT / ALPHA
* ; any VCHAR, except delimiters
*
* @see https://datatracker.ietf.org/doc/html/rfc7230#section-3.2.6
*/
const validFieldnameRE = /^[!#$%&'*+\-.^\w`|~]+$/u
function validateFieldname (fieldname) {
if (validFieldnameRE.test(fieldname) === false) {
throw new TypeError('Fieldname contains invalid characters.')
}
}
function parse (header) {
header = header.trim().toLowerCase()
const result = []
if (header.length === 0) {
// pass through
} else if (header.indexOf(',') === -1) {
result.push(header)
} else {
const il = header.length
let i = 0
let pos = 0
let char
// tokenize the header
for (i = 0; i < il; ++i) {
char = header[i]
// when we have whitespace set the pos to the next position
if (char === ' ') {
pos = i + 1
// `,` is the separator of vary-values
} else if (char === ',') {
// if pos and current position are not the same we have a valid token
if (pos !== i) {
result.push(header.slice(pos, i))
}
// reset the positions
pos = i + 1
}
}
if (pos !== i) {
result.push(header.slice(pos, i))
}
}
return result
}
function createAddFieldnameToVary (fieldname) {
const headerCache = new LRUCache(1000)
validateFieldname(fieldname)
return function (reply) {
let header = reply.getHeader('Vary')
if (!header) {
reply.header('Vary', fieldname)
return
}
if (header === '*') {
return
}
if (fieldname === '*') {
reply.header('Vary', '*')
return
}
if (Array.isArray(header)) {
header = header.join(', ')
}
if (!headerCache.has(header)) {
const vals = parse(header)
if (vals.indexOf('*') !== -1) {
headerCache.set(header, '*')
} else if (vals.indexOf(fieldname.toLowerCase()) === -1) {
headerCache.set(header, header + ', ' + fieldname)
} else {
headerCache.set(header, null)
}
}
const cached = headerCache.get(header)
if (cached !== null) {
reply.header('Vary', cached)
}
}
}
module.exports.createAddFieldnameToVary = createAddFieldnameToVary
module.exports.addOriginToVaryHeader = createAddFieldnameToVary('Origin')
module.exports.addAccessControlRequestHeadersToVaryHeader = createAddFieldnameToVary('Access-Control-Request-Headers')
module.exports.parse = parse