mirror of https://github.com/gchq/CyberChef.git
99 lines
2.9 KiB
JavaScript
99 lines
2.9 KiB
JavaScript
/**
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* @author tedk [tedk@ted.do]
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* @copyright Crown Copyright 2024
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* @license Apache-2.0
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*/
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import Operation from "../Operation.mjs";
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/**
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* Caret/M-decode operation
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*
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* https://gist.githubusercontent.com/JaHIY/3c91bbf7bea5661e6abfbd1349ee81a2/raw/c7b480e9ff24bcb8f5287a8a8a2dcb9bf5628506/decode_m_notation.cpp
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*/
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class CaretMdecode extends Operation {
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/**
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* CaretMdecode constructor
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*/
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constructor() {
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super();
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this.name = "Caret/M-decode";
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this.module = "Default";
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this.description = "Decodes caret or M-encoded strings, i.e. ^M turns into a newline, M-^] turns into 0x9d. Sources such as `cat -v`.\n\nPlease be aware that when using `cat -v` ^_ (caret-underscore) will not be encoded, but represents a valid encoding (namely that of 0x1f).";
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this.infoURL = "https://en.wikipedia.org/wiki/Caret_notation";
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this.inputType = "string";
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this.outputType = "byteArray";
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this.args = [];
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}
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/**
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* @param {string} input
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* @param {Object[]} args
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* @returns {byteArray}
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*/
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run(input, args) {
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const bytes = [];
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let prev = "";
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for (let i = 0; i < input.length; i++) {
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const charCode = input.charCodeAt(i);
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const curChar = input.charAt(i);
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if (prev === "M-^") {
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if (charCode > 63 && charCode <= 95) {
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bytes.push(charCode + 64);
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} else if (charCode === 63) {
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bytes.push(255);
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} else {
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bytes.push(77, 45, 94, charCode);
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}
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prev = "";
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} else if (prev === "M-") {
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if (curChar === "^") {
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prev = prev + "^";
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} else if (charCode >= 32 && charCode <= 126) {
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bytes.push(charCode + 128);
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prev = "";
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} else {
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bytes.push(77, 45, charCode);
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prev = "";
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}
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} else if (prev === "M") {
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if (curChar === "-") {
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prev = prev + "-";
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} else {
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bytes.push(77, charCode);
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prev = "";
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}
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} else if (prev === "^") {
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if (charCode > 63 && charCode <= 126) {
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bytes.push(charCode - 64);
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} else if (charCode === 63) {
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bytes.push(127);
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} else {
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bytes.push(94, charCode);
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}
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prev = "";
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} else {
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if (curChar === "M") {
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prev = "M";
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} else if (curChar === "^") {
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prev = "^";
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} else {
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bytes.push(charCode);
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}
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}
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}
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return bytes;
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}
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}
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export default CaretMdecode;
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