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'use strict';
// Value of https://w3c.github.io/webappsec-subresource-integrity/#the-integrity-attribute
// Returns [{algorithm, value (in base64 string), options,}]
const {
ERR_SRI_PARSE
} = require('internal/errors').codes;
const kWSP = '[\\x20\\x09]';
const kVCHAR = '[\\x21-\\x7E]';
const kHASH_ALGO = 'sha256|sha384|sha512';
// Base64
const kHASH_VALUE = '[A-Za-z0-9+/]+[=]{0,2}';
const kHASH_EXPRESSION = `(${kHASH_ALGO})-(${kHASH_VALUE})`;
const kOPTION_EXPRESSION = `(${kVCHAR}*)`;
const kHASH_WITH_OPTIONS = `${kHASH_EXPRESSION}(?:[?](${kOPTION_EXPRESSION}))?`;
const kSRIPattern = new RegExp(`(${kWSP}*)(?:${kHASH_WITH_OPTIONS})`, 'g');
const { freeze } = Object;
Object.seal(kSRIPattern);
const kAllWSP = new RegExp(`^${kWSP}*$`);
Object.seal(kAllWSP);
const RegExpExec = Function.call.bind(RegExp.prototype.exec);
const RegExpTest = Function.call.bind(RegExp.prototype.test);
const StringSlice = Function.call.bind(String.prototype.slice);
const BufferFrom = require('buffer').Buffer.from;
const { defineProperty } = Object;
const parse = (str) => {
kSRIPattern.lastIndex = 0;
let prevIndex = 0;
let match;
const entries = [];
while (match = RegExpExec(kSRIPattern, str)) {
if (match.index !== prevIndex) {
throw new ERR_SRI_PARSE(str, prevIndex);
}
if (entries.length > 0 && match[1] === '') {
throw new ERR_SRI_PARSE(str, prevIndex);
}
// Avoid setters being fired
defineProperty(entries, entries.length, {
enumerable: true,
configurable: true,
value: freeze({
__proto__: null,
algorithm: match[2],
value: BufferFrom(match[3], 'base64'),
options: match[4] === undefined ? null : match[4],
})
});
prevIndex = prevIndex + match[0].length;
}
if (prevIndex !== str.length) {
if (!RegExpTest(kAllWSP, StringSlice(str, prevIndex))) {
throw new ERR_SRI_PARSE(str, prevIndex);
}
}
return entries;
};
module.exports = {
parse,
};
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