mirror of https://github.com/gchq/CyberChef.git
79 lines
1.6 KiB
JavaScript
79 lines
1.6 KiB
JavaScript
/**
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* Parser for Type-length-value data.
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*
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* @author gchq77703 []
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* @author n1474335 [n1474335@gmail.com]
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* @copyright Crown Copyright 2018
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* @license Apache-2.0
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*/
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const defaults = {
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location: 0,
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bytesInLength: 1,
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basicEncodingRules: false
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};
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/**
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* TLVParser library
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*/
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export default class TLVParser {
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/**
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* TLVParser constructor
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*
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* @param {byteArray|Uint8Array} input
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* @param {Object} options
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*/
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constructor(input, options) {
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this.input = input;
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Object.assign(this, defaults, options);
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}
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/**
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* @returns {number}
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*/
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getLength() {
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if (this.basicEncodingRules) {
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const bit = this.input[this.location];
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if (bit & 0x80) {
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this.bytesInLength = bit & ~0x80;
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} else {
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this.location++;
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return bit & ~0x80;
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}
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}
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let length = 0;
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for (let i = 0; i < this.bytesInLength; i++) {
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length += this.input[this.location] * Math.pow(Math.pow(2, 8), i);
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this.location++;
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}
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return length;
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}
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/**
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* @param {number} length
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* @returns {number[]}
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*/
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getValue(length) {
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const value = [];
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for (let i = 0; i < length; i++) {
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if (this.location > this.input.length) return value;
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value.push(this.input[this.location]);
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this.location++;
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}
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return value;
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}
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/**
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* @returns {boolean}
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*/
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atEnd() {
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return this.input.length <= this.location;
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}
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}
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