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395 lines
12 KiB
395 lines
12 KiB
'use strict' |
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const crypto = require('crypto') |
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const figgyPudding = require('figgy-pudding') |
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const Transform = require('stream').Transform |
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const SPEC_ALGORITHMS = ['sha256', 'sha384', 'sha512'] |
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const BASE64_REGEX = /^[a-z0-9+/]+(?:=?=?)$/i |
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const SRI_REGEX = /^([^-]+)-([^?]+)([?\S*]*)$/ |
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const STRICT_SRI_REGEX = /^([^-]+)-([A-Za-z0-9+/=]{44,88})(\?[\x21-\x7E]*)?$/ |
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const VCHAR_REGEX = /^[\x21-\x7E]+$/ |
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const SsriOpts = figgyPudding({ |
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algorithms: {default: ['sha512']}, |
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error: {default: false}, |
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integrity: {}, |
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options: {default: []}, |
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pickAlgorithm: {default: () => getPrioritizedHash}, |
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Promise: {default: () => Promise}, |
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sep: {default: ' '}, |
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single: {default: false}, |
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size: {}, |
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strict: {default: false} |
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}) |
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class Hash { |
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get isHash () { return true } |
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constructor (hash, opts) { |
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opts = SsriOpts(opts) |
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const strict = !!opts.strict |
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this.source = hash.trim() |
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// 3.1. Integrity metadata (called "Hash" by ssri) |
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// https://w3c.github.io/webappsec-subresource-integrity/#integrity-metadata-description |
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const match = this.source.match( |
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strict |
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? STRICT_SRI_REGEX |
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: SRI_REGEX |
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) |
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if (!match) { return } |
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if (strict && !SPEC_ALGORITHMS.some(a => a === match[1])) { return } |
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this.algorithm = match[1] |
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this.digest = match[2] |
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const rawOpts = match[3] |
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this.options = rawOpts ? rawOpts.slice(1).split('?') : [] |
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} |
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hexDigest () { |
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return this.digest && Buffer.from(this.digest, 'base64').toString('hex') |
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} |
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toJSON () { |
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return this.toString() |
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} |
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toString (opts) { |
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opts = SsriOpts(opts) |
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if (opts.strict) { |
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// Strict mode enforces the standard as close to the foot of the |
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// letter as it can. |
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if (!( |
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// The spec has very restricted productions for algorithms. |
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// https://www.w3.org/TR/CSP2/#source-list-syntax |
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SPEC_ALGORITHMS.some(x => x === this.algorithm) && |
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// Usually, if someone insists on using a "different" base64, we |
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// leave it as-is, since there's multiple standards, and the |
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// specified is not a URL-safe variant. |
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// https://www.w3.org/TR/CSP2/#base64_value |
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this.digest.match(BASE64_REGEX) && |
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// Option syntax is strictly visual chars. |
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// https://w3c.github.io/webappsec-subresource-integrity/#grammardef-option-expression |
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// https://tools.ietf.org/html/rfc5234#appendix-B.1 |
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(this.options || []).every(opt => opt.match(VCHAR_REGEX)) |
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)) { |
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return '' |
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} |
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} |
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const options = this.options && this.options.length |
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? `?${this.options.join('?')}` |
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: '' |
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return `${this.algorithm}-${this.digest}${options}` |
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} |
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} |
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class Integrity { |
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get isIntegrity () { return true } |
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toJSON () { |
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return this.toString() |
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} |
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toString (opts) { |
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opts = SsriOpts(opts) |
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let sep = opts.sep || ' ' |
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if (opts.strict) { |
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// Entries must be separated by whitespace, according to spec. |
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sep = sep.replace(/\S+/g, ' ') |
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} |
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return Object.keys(this).map(k => { |
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return this[k].map(hash => { |
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return Hash.prototype.toString.call(hash, opts) |
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}).filter(x => x.length).join(sep) |
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}).filter(x => x.length).join(sep) |
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} |
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concat (integrity, opts) { |
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opts = SsriOpts(opts) |
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const other = typeof integrity === 'string' |
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? integrity |
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: stringify(integrity, opts) |
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return parse(`${this.toString(opts)} ${other}`, opts) |
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} |
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hexDigest () { |
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return parse(this, {single: true}).hexDigest() |
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} |
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match (integrity, opts) { |
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opts = SsriOpts(opts) |
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const other = parse(integrity, opts) |
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const algo = other.pickAlgorithm(opts) |
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return ( |
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this[algo] && |
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other[algo] && |
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this[algo].find(hash => |
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other[algo].find(otherhash => |
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hash.digest === otherhash.digest |
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) |
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) |
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) || false |
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} |
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pickAlgorithm (opts) { |
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opts = SsriOpts(opts) |
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const pickAlgorithm = opts.pickAlgorithm |
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const keys = Object.keys(this) |
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if (!keys.length) { |
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throw new Error(`No algorithms available for ${ |
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JSON.stringify(this.toString()) |
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}`) |
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} |
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return keys.reduce((acc, algo) => { |
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return pickAlgorithm(acc, algo) || acc |
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}) |
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} |
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} |
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module.exports.parse = parse |
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function parse (sri, opts) { |
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opts = SsriOpts(opts) |
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if (typeof sri === 'string') { |
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return _parse(sri, opts) |
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} else if (sri.algorithm && sri.digest) { |
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const fullSri = new Integrity() |
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fullSri[sri.algorithm] = [sri] |
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return _parse(stringify(fullSri, opts), opts) |
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} else { |
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return _parse(stringify(sri, opts), opts) |
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} |
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} |
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function _parse (integrity, opts) { |
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// 3.4.3. Parse metadata |
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// https://w3c.github.io/webappsec-subresource-integrity/#parse-metadata |
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if (opts.single) { |
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return new Hash(integrity, opts) |
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} |
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return integrity.trim().split(/\s+/).reduce((acc, string) => { |
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const hash = new Hash(string, opts) |
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if (hash.algorithm && hash.digest) { |
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const algo = hash.algorithm |
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if (!acc[algo]) { acc[algo] = [] } |
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acc[algo].push(hash) |
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} |
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return acc |
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}, new Integrity()) |
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} |
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module.exports.stringify = stringify |
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function stringify (obj, opts) { |
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opts = SsriOpts(opts) |
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if (obj.algorithm && obj.digest) { |
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return Hash.prototype.toString.call(obj, opts) |
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} else if (typeof obj === 'string') { |
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return stringify(parse(obj, opts), opts) |
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} else { |
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return Integrity.prototype.toString.call(obj, opts) |
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} |
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} |
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module.exports.fromHex = fromHex |
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function fromHex (hexDigest, algorithm, opts) { |
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opts = SsriOpts(opts) |
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const optString = opts.options && opts.options.length |
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? `?${opts.options.join('?')}` |
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: '' |
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return parse( |
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`${algorithm}-${ |
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Buffer.from(hexDigest, 'hex').toString('base64') |
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}${optString}`, opts |
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) |
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} |
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module.exports.fromData = fromData |
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function fromData (data, opts) { |
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opts = SsriOpts(opts) |
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const algorithms = opts.algorithms |
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const optString = opts.options && opts.options.length |
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? `?${opts.options.join('?')}` |
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: '' |
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return algorithms.reduce((acc, algo) => { |
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const digest = crypto.createHash(algo).update(data).digest('base64') |
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const hash = new Hash( |
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`${algo}-${digest}${optString}`, |
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opts |
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) |
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if (hash.algorithm && hash.digest) { |
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const algo = hash.algorithm |
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if (!acc[algo]) { acc[algo] = [] } |
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acc[algo].push(hash) |
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} |
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return acc |
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}, new Integrity()) |
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} |
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module.exports.fromStream = fromStream |
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function fromStream (stream, opts) { |
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opts = SsriOpts(opts) |
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const P = opts.Promise || Promise |
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const istream = integrityStream(opts) |
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return new P((resolve, reject) => { |
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stream.pipe(istream) |
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stream.on('error', reject) |
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istream.on('error', reject) |
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let sri |
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istream.on('integrity', s => { sri = s }) |
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istream.on('end', () => resolve(sri)) |
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istream.on('data', () => {}) |
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}) |
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} |
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module.exports.checkData = checkData |
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function checkData (data, sri, opts) { |
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opts = SsriOpts(opts) |
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sri = parse(sri, opts) |
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if (!Object.keys(sri).length) { |
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if (opts.error) { |
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throw Object.assign( |
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new Error('No valid integrity hashes to check against'), { |
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code: 'EINTEGRITY' |
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} |
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) |
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} else { |
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return false |
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} |
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} |
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const algorithm = sri.pickAlgorithm(opts) |
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const digest = crypto.createHash(algorithm).update(data).digest('base64') |
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const newSri = parse({algorithm, digest}) |
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const match = newSri.match(sri, opts) |
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if (match || !opts.error) { |
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return match |
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} else if (typeof opts.size === 'number' && (data.length !== opts.size)) { |
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const err = new Error(`data size mismatch when checking ${sri}.\n Wanted: ${opts.size}\n Found: ${data.length}`) |
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err.code = 'EBADSIZE' |
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err.found = data.length |
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err.expected = opts.size |
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err.sri = sri |
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throw err |
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} else { |
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const err = new Error(`Integrity checksum failed when using ${algorithm}: Wanted ${sri}, but got ${newSri}. (${data.length} bytes)`) |
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err.code = 'EINTEGRITY' |
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err.found = newSri |
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err.expected = sri |
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err.algorithm = algorithm |
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err.sri = sri |
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throw err |
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} |
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} |
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module.exports.checkStream = checkStream |
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function checkStream (stream, sri, opts) { |
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opts = SsriOpts(opts) |
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const P = opts.Promise || Promise |
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const checker = integrityStream(opts.concat({ |
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integrity: sri |
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})) |
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return new P((resolve, reject) => { |
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stream.pipe(checker) |
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stream.on('error', reject) |
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checker.on('error', reject) |
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let sri |
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checker.on('verified', s => { sri = s }) |
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checker.on('end', () => resolve(sri)) |
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checker.on('data', () => {}) |
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}) |
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} |
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module.exports.integrityStream = integrityStream |
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function integrityStream (opts) { |
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opts = SsriOpts(opts) |
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// For verification |
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const sri = opts.integrity && parse(opts.integrity, opts) |
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const goodSri = sri && Object.keys(sri).length |
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const algorithm = goodSri && sri.pickAlgorithm(opts) |
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const digests = goodSri && sri[algorithm] |
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// Calculating stream |
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const algorithms = Array.from( |
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new Set(opts.algorithms.concat(algorithm ? [algorithm] : [])) |
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) |
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const hashes = algorithms.map(crypto.createHash) |
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let streamSize = 0 |
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const stream = new Transform({ |
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transform (chunk, enc, cb) { |
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streamSize += chunk.length |
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hashes.forEach(h => h.update(chunk, enc)) |
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cb(null, chunk, enc) |
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} |
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}).on('end', () => { |
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const optString = (opts.options && opts.options.length) |
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? `?${opts.options.join('?')}` |
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: '' |
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const newSri = parse(hashes.map((h, i) => { |
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return `${algorithms[i]}-${h.digest('base64')}${optString}` |
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}).join(' '), opts) |
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// Integrity verification mode |
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const match = goodSri && newSri.match(sri, opts) |
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if (typeof opts.size === 'number' && streamSize !== opts.size) { |
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const err = new Error(`stream size mismatch when checking ${sri}.\n Wanted: ${opts.size}\n Found: ${streamSize}`) |
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err.code = 'EBADSIZE' |
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err.found = streamSize |
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err.expected = opts.size |
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err.sri = sri |
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stream.emit('error', err) |
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} else if (opts.integrity && !match) { |
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const err = new Error(`${sri} integrity checksum failed when using ${algorithm}: wanted ${digests} but got ${newSri}. (${streamSize} bytes)`) |
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err.code = 'EINTEGRITY' |
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err.found = newSri |
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err.expected = digests |
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err.algorithm = algorithm |
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err.sri = sri |
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stream.emit('error', err) |
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} else { |
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stream.emit('size', streamSize) |
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stream.emit('integrity', newSri) |
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match && stream.emit('verified', match) |
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} |
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}) |
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return stream |
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} |
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module.exports.create = createIntegrity |
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function createIntegrity (opts) { |
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opts = SsriOpts(opts) |
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const algorithms = opts.algorithms |
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const optString = opts.options.length |
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? `?${opts.options.join('?')}` |
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: '' |
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const hashes = algorithms.map(crypto.createHash) |
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return { |
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update: function (chunk, enc) { |
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hashes.forEach(h => h.update(chunk, enc)) |
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return this |
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}, |
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digest: function (enc) { |
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const integrity = algorithms.reduce((acc, algo) => { |
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const digest = hashes.shift().digest('base64') |
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const hash = new Hash( |
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`${algo}-${digest}${optString}`, |
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opts |
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) |
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if (hash.algorithm && hash.digest) { |
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const algo = hash.algorithm |
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if (!acc[algo]) { acc[algo] = [] } |
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acc[algo].push(hash) |
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} |
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return acc |
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}, new Integrity()) |
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return integrity |
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} |
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} |
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} |
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const NODE_HASHES = new Set(crypto.getHashes()) |
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// This is a Best Effort™ at a reasonable priority for hash algos |
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const DEFAULT_PRIORITY = [ |
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'md5', 'whirlpool', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512', |
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// TODO - it's unclear _which_ of these Node will actually use as its name |
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// for the algorithm, so we guesswork it based on the OpenSSL names. |
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'sha3', |
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'sha3-256', 'sha3-384', 'sha3-512', |
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'sha3_256', 'sha3_384', 'sha3_512' |
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].filter(algo => NODE_HASHES.has(algo)) |
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function getPrioritizedHash (algo1, algo2) { |
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return DEFAULT_PRIORITY.indexOf(algo1.toLowerCase()) >= DEFAULT_PRIORITY.indexOf(algo2.toLowerCase()) |
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? algo1 |
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: algo2 |
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}
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