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							- 'use strict'
 
- const crypto = require('crypto')
 
- const MiniPass = require('minipass')
 
- const SPEC_ALGORITHMS = ['sha256', 'sha384', 'sha512']
 
- // TODO: this should really be a hardcoded list of algorithms we support,
 
- // rather than [a-z0-9].
 
- const BASE64_REGEX = /^[a-z0-9+/]+(?:=?=?)$/i
 
- const SRI_REGEX = /^([a-z0-9]+)-([^?]+)([?\S*]*)$/
 
- const STRICT_SRI_REGEX = /^([a-z0-9]+)-([A-Za-z0-9+/=]{44,88})(\?[\x21-\x7E]*)?$/
 
- const VCHAR_REGEX = /^[\x21-\x7E]+$/
 
- const defaultOpts = {
 
-   algorithms: ['sha512'],
 
-   error: false,
 
-   options: [],
 
-   pickAlgorithm: getPrioritizedHash,
 
-   sep: ' ',
 
-   single: false,
 
-   strict: false
 
- }
 
- const ssriOpts = (opts = {}) => ({ ...defaultOpts, ...opts })
 
- const getOptString = options => !options || !options.length
 
-   ? ''
 
-   : `?${options.join('?')}`
 
- const _onEnd = Symbol('_onEnd')
 
- const _getOptions = Symbol('_getOptions')
 
- class IntegrityStream extends MiniPass {
 
-   constructor (opts) {
 
-     super()
 
-     this.size = 0
 
-     this.opts = opts
 
-     // may be overridden later, but set now for class consistency
 
-     this[_getOptions]()
 
-     // options used for calculating stream.  can't be changed.
 
-     const { algorithms = defaultOpts.algorithms } = opts
 
-     this.algorithms = Array.from(
 
-       new Set(algorithms.concat(this.algorithm ? [this.algorithm] : []))
 
-     )
 
-     this.hashes = this.algorithms.map(crypto.createHash)
 
-   }
 
-   [_getOptions] () {
 
-     const {
 
-       integrity,
 
-       size,
 
-       options
 
-     } = { ...defaultOpts, ...this.opts }
 
-     // For verification
 
-     this.sri = integrity ? parse(integrity, this.opts) : null
 
-     this.expectedSize = size
 
-     this.goodSri = this.sri ? !!Object.keys(this.sri).length : false
 
-     this.algorithm = this.goodSri ? this.sri.pickAlgorithm(this.opts) : null
 
-     this.digests = this.goodSri ? this.sri[this.algorithm] : null
 
-     this.optString = getOptString(options)
 
-   }
 
-   emit (ev, data) {
 
-     if (ev === 'end') this[_onEnd]()
 
-     return super.emit(ev, data)
 
-   }
 
-   write (data) {
 
-     this.size += data.length
 
-     this.hashes.forEach(h => h.update(data))
 
-     return super.write(data)
 
-   }
 
-   [_onEnd] () {
 
-     if (!this.goodSri) {
 
-       this[_getOptions]()
 
-     }
 
-     const newSri = parse(this.hashes.map((h, i) => {
 
-       return `${this.algorithms[i]}-${h.digest('base64')}${this.optString}`
 
-     }).join(' '), this.opts)
 
-     // Integrity verification mode
 
-     const match = this.goodSri && newSri.match(this.sri, this.opts)
 
-     if (typeof this.expectedSize === 'number' && this.size !== this.expectedSize) {
 
-       const err = new Error(`stream size mismatch when checking ${this.sri}.\n  Wanted: ${this.expectedSize}\n  Found: ${this.size}`)
 
-       err.code = 'EBADSIZE'
 
-       err.found = this.size
 
-       err.expected = this.expectedSize
 
-       err.sri = this.sri
 
-       this.emit('error', err)
 
-     } else if (this.sri && !match) {
 
-       const err = new Error(`${this.sri} integrity checksum failed when using ${this.algorithm}: wanted ${this.digests} but got ${newSri}. (${this.size} bytes)`)
 
-       err.code = 'EINTEGRITY'
 
-       err.found = newSri
 
-       err.expected = this.digests
 
-       err.algorithm = this.algorithm
 
-       err.sri = this.sri
 
-       this.emit('error', err)
 
-     } else {
 
-       this.emit('size', this.size)
 
-       this.emit('integrity', newSri)
 
-       match && this.emit('verified', match)
 
-     }
 
-   }
 
- }
 
- class Hash {
 
-   get isHash () { return true }
 
-   constructor (hash, opts) {
 
-     opts = ssriOpts(opts)
 
-     const strict = !!opts.strict
 
-     this.source = hash.trim()
 
-     // set default values so that we make V8 happy to
 
-     // always see a familiar object template.
 
-     this.digest = ''
 
-     this.algorithm = ''
 
-     this.options = []
 
-     // 3.1. Integrity metadata (called "Hash" by ssri)
 
-     // https://w3c.github.io/webappsec-subresource-integrity/#integrity-metadata-description
 
-     const match = this.source.match(
 
-       strict
 
-         ? STRICT_SRI_REGEX
 
-         : SRI_REGEX
 
-     )
 
-     if (!match) { return }
 
-     if (strict && !SPEC_ALGORITHMS.some(a => a === match[1])) { return }
 
-     this.algorithm = match[1]
 
-     this.digest = match[2]
 
-     const rawOpts = match[3]
 
-     if (rawOpts) {
 
-       this.options = rawOpts.slice(1).split('?')
 
-     }
 
-   }
 
-   hexDigest () {
 
-     return this.digest && Buffer.from(this.digest, 'base64').toString('hex')
 
-   }
 
-   toJSON () {
 
-     return this.toString()
 
-   }
 
-   toString (opts) {
 
-     opts = ssriOpts(opts)
 
-     if (opts.strict) {
 
-       // Strict mode enforces the standard as close to the foot of the
 
-       // letter as it can.
 
-       if (!(
 
-         // The spec has very restricted productions for algorithms.
 
-         // https://www.w3.org/TR/CSP2/#source-list-syntax
 
-         SPEC_ALGORITHMS.some(x => x === this.algorithm) &&
 
-         // Usually, if someone insists on using a "different" base64, we
 
-         // leave it as-is, since there's multiple standards, and the
 
-         // specified is not a URL-safe variant.
 
-         // https://www.w3.org/TR/CSP2/#base64_value
 
-         this.digest.match(BASE64_REGEX) &&
 
-         // Option syntax is strictly visual chars.
 
-         // https://w3c.github.io/webappsec-subresource-integrity/#grammardef-option-expression
 
-         // https://tools.ietf.org/html/rfc5234#appendix-B.1
 
-         this.options.every(opt => opt.match(VCHAR_REGEX))
 
-       )) {
 
-         return ''
 
-       }
 
-     }
 
-     const options = this.options && this.options.length
 
-       ? `?${this.options.join('?')}`
 
-       : ''
 
-     return `${this.algorithm}-${this.digest}${options}`
 
-   }
 
- }
 
- class Integrity {
 
-   get isIntegrity () { return true }
 
-   toJSON () {
 
-     return this.toString()
 
-   }
 
-   isEmpty () {
 
-     return Object.keys(this).length === 0
 
-   }
 
-   toString (opts) {
 
-     opts = ssriOpts(opts)
 
-     let sep = opts.sep || ' '
 
-     if (opts.strict) {
 
-       // Entries must be separated by whitespace, according to spec.
 
-       sep = sep.replace(/\S+/g, ' ')
 
-     }
 
-     return Object.keys(this).map(k => {
 
-       return this[k].map(hash => {
 
-         return Hash.prototype.toString.call(hash, opts)
 
-       }).filter(x => x.length).join(sep)
 
-     }).filter(x => x.length).join(sep)
 
-   }
 
-   concat (integrity, opts) {
 
-     opts = ssriOpts(opts)
 
-     const other = typeof integrity === 'string'
 
-       ? integrity
 
-       : stringify(integrity, opts)
 
-     return parse(`${this.toString(opts)} ${other}`, opts)
 
-   }
 
-   hexDigest () {
 
-     return parse(this, { single: true }).hexDigest()
 
-   }
 
-   // add additional hashes to an integrity value, but prevent
 
-   // *changing* an existing integrity hash.
 
-   merge (integrity, opts) {
 
-     opts = ssriOpts(opts)
 
-     const other = parse(integrity, opts)
 
-     for (const algo in other) {
 
-       if (this[algo]) {
 
-         if (!this[algo].find(hash =>
 
-           other[algo].find(otherhash =>
 
-             hash.digest === otherhash.digest))) {
 
-           throw new Error('hashes do not match, cannot update integrity')
 
-         }
 
-       } else {
 
-         this[algo] = other[algo]
 
-       }
 
-     }
 
-   }
 
-   match (integrity, opts) {
 
-     opts = ssriOpts(opts)
 
-     const other = parse(integrity, opts)
 
-     const algo = other.pickAlgorithm(opts)
 
-     return (
 
-       this[algo] &&
 
-       other[algo] &&
 
-       this[algo].find(hash =>
 
-         other[algo].find(otherhash =>
 
-           hash.digest === otherhash.digest
 
-         )
 
-       )
 
-     ) || false
 
-   }
 
-   pickAlgorithm (opts) {
 
-     opts = ssriOpts(opts)
 
-     const pickAlgorithm = opts.pickAlgorithm
 
-     const keys = Object.keys(this)
 
-     return keys.reduce((acc, algo) => {
 
-       return pickAlgorithm(acc, algo) || acc
 
-     })
 
-   }
 
- }
 
- module.exports.parse = parse
 
- function parse (sri, opts) {
 
-   if (!sri) return null
 
-   opts = ssriOpts(opts)
 
-   if (typeof sri === 'string') {
 
-     return _parse(sri, opts)
 
-   } else if (sri.algorithm && sri.digest) {
 
-     const fullSri = new Integrity()
 
-     fullSri[sri.algorithm] = [sri]
 
-     return _parse(stringify(fullSri, opts), opts)
 
-   } else {
 
-     return _parse(stringify(sri, opts), opts)
 
-   }
 
- }
 
- function _parse (integrity, opts) {
 
-   // 3.4.3. Parse metadata
 
-   // https://w3c.github.io/webappsec-subresource-integrity/#parse-metadata
 
-   if (opts.single) {
 
-     return new Hash(integrity, opts)
 
-   }
 
-   const hashes = integrity.trim().split(/\s+/).reduce((acc, string) => {
 
-     const hash = new Hash(string, opts)
 
-     if (hash.algorithm && hash.digest) {
 
-       const algo = hash.algorithm
 
-       if (!acc[algo]) { acc[algo] = [] }
 
-       acc[algo].push(hash)
 
-     }
 
-     return acc
 
-   }, new Integrity())
 
-   return hashes.isEmpty() ? null : hashes
 
- }
 
- module.exports.stringify = stringify
 
- function stringify (obj, opts) {
 
-   opts = ssriOpts(opts)
 
-   if (obj.algorithm && obj.digest) {
 
-     return Hash.prototype.toString.call(obj, opts)
 
-   } else if (typeof obj === 'string') {
 
-     return stringify(parse(obj, opts), opts)
 
-   } else {
 
-     return Integrity.prototype.toString.call(obj, opts)
 
-   }
 
- }
 
- module.exports.fromHex = fromHex
 
- function fromHex (hexDigest, algorithm, opts) {
 
-   opts = ssriOpts(opts)
 
-   const optString = getOptString(opts.options)
 
-   return parse(
 
-     `${algorithm}-${
 
-       Buffer.from(hexDigest, 'hex').toString('base64')
 
-     }${optString}`, opts
 
-   )
 
- }
 
- module.exports.fromData = fromData
 
- function fromData (data, opts) {
 
-   opts = ssriOpts(opts)
 
-   const algorithms = opts.algorithms
 
-   const optString = getOptString(opts.options)
 
-   return algorithms.reduce((acc, algo) => {
 
-     const digest = crypto.createHash(algo).update(data).digest('base64')
 
-     const hash = new Hash(
 
-       `${algo}-${digest}${optString}`,
 
-       opts
 
-     )
 
-     /* istanbul ignore else - it would be VERY strange if the string we
 
-      * just calculated with an algo did not have an algo or digest.
 
-      */
 
-     if (hash.algorithm && hash.digest) {
 
-       const algo = hash.algorithm
 
-       if (!acc[algo]) { acc[algo] = [] }
 
-       acc[algo].push(hash)
 
-     }
 
-     return acc
 
-   }, new Integrity())
 
- }
 
- module.exports.fromStream = fromStream
 
- function fromStream (stream, opts) {
 
-   opts = ssriOpts(opts)
 
-   const istream = integrityStream(opts)
 
-   return new Promise((resolve, reject) => {
 
-     stream.pipe(istream)
 
-     stream.on('error', reject)
 
-     istream.on('error', reject)
 
-     let sri
 
-     istream.on('integrity', s => { sri = s })
 
-     istream.on('end', () => resolve(sri))
 
-     istream.on('data', () => {})
 
-   })
 
- }
 
- module.exports.checkData = checkData
 
- function checkData (data, sri, opts) {
 
-   opts = ssriOpts(opts)
 
-   sri = parse(sri, opts)
 
-   if (!sri || !Object.keys(sri).length) {
 
-     if (opts.error) {
 
-       throw Object.assign(
 
-         new Error('No valid integrity hashes to check against'), {
 
-           code: 'EINTEGRITY'
 
-         }
 
-       )
 
-     } else {
 
-       return false
 
-     }
 
-   }
 
-   const algorithm = sri.pickAlgorithm(opts)
 
-   const digest = crypto.createHash(algorithm).update(data).digest('base64')
 
-   const newSri = parse({ algorithm, digest })
 
-   const match = newSri.match(sri, opts)
 
-   if (match || !opts.error) {
 
-     return match
 
-   } else if (typeof opts.size === 'number' && (data.length !== opts.size)) {
 
-     const err = new Error(`data size mismatch when checking ${sri}.\n  Wanted: ${opts.size}\n  Found: ${data.length}`)
 
-     err.code = 'EBADSIZE'
 
-     err.found = data.length
 
-     err.expected = opts.size
 
-     err.sri = sri
 
-     throw err
 
-   } else {
 
-     const err = new Error(`Integrity checksum failed when using ${algorithm}: Wanted ${sri}, but got ${newSri}. (${data.length} bytes)`)
 
-     err.code = 'EINTEGRITY'
 
-     err.found = newSri
 
-     err.expected = sri
 
-     err.algorithm = algorithm
 
-     err.sri = sri
 
-     throw err
 
-   }
 
- }
 
- module.exports.checkStream = checkStream
 
- function checkStream (stream, sri, opts) {
 
-   opts = ssriOpts(opts)
 
-   opts.integrity = sri
 
-   sri = parse(sri, opts)
 
-   if (!sri || !Object.keys(sri).length) {
 
-     return Promise.reject(Object.assign(
 
-       new Error('No valid integrity hashes to check against'), {
 
-         code: 'EINTEGRITY'
 
-       }
 
-     ))
 
-   }
 
-   const checker = integrityStream(opts)
 
-   return new Promise((resolve, reject) => {
 
-     stream.pipe(checker)
 
-     stream.on('error', reject)
 
-     checker.on('error', reject)
 
-     let sri
 
-     checker.on('verified', s => { sri = s })
 
-     checker.on('end', () => resolve(sri))
 
-     checker.on('data', () => {})
 
-   })
 
- }
 
- module.exports.integrityStream = integrityStream
 
- function integrityStream (opts = {}) {
 
-   return new IntegrityStream(opts)
 
- }
 
- module.exports.create = createIntegrity
 
- function createIntegrity (opts) {
 
-   opts = ssriOpts(opts)
 
-   const algorithms = opts.algorithms
 
-   const optString = getOptString(opts.options)
 
-   const hashes = algorithms.map(crypto.createHash)
 
-   return {
 
-     update: function (chunk, enc) {
 
-       hashes.forEach(h => h.update(chunk, enc))
 
-       return this
 
-     },
 
-     digest: function (enc) {
 
-       const integrity = algorithms.reduce((acc, algo) => {
 
-         const digest = hashes.shift().digest('base64')
 
-         const hash = new Hash(
 
-           `${algo}-${digest}${optString}`,
 
-           opts
 
-         )
 
-         /* istanbul ignore else - it would be VERY strange if the hash we
 
-          * just calculated with an algo did not have an algo or digest.
 
-          */
 
-         if (hash.algorithm && hash.digest) {
 
-           const algo = hash.algorithm
 
-           if (!acc[algo]) { acc[algo] = [] }
 
-           acc[algo].push(hash)
 
-         }
 
-         return acc
 
-       }, new Integrity())
 
-       return integrity
 
-     }
 
-   }
 
- }
 
- const NODE_HASHES = new Set(crypto.getHashes())
 
- // This is a Best Effort™ at a reasonable priority for hash algos
 
- const DEFAULT_PRIORITY = [
 
-   'md5', 'whirlpool', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512',
 
-   // TODO - it's unclear _which_ of these Node will actually use as its name
 
-   //        for the algorithm, so we guesswork it based on the OpenSSL names.
 
-   'sha3',
 
-   'sha3-256', 'sha3-384', 'sha3-512',
 
-   'sha3_256', 'sha3_384', 'sha3_512'
 
- ].filter(algo => NODE_HASHES.has(algo))
 
- function getPrioritizedHash (algo1, algo2) {
 
-   return DEFAULT_PRIORITY.indexOf(algo1.toLowerCase()) >= DEFAULT_PRIORITY.indexOf(algo2.toLowerCase())
 
-     ? algo1
 
-     : algo2
 
- }
 
 
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