111 lines
2.9 KiB
JavaScript
111 lines
2.9 KiB
JavaScript
/**
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* Base64 Encodes an arraybuffer
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* @param {ArrayBuffer} arraybuffer
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* @returns {string}
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*/
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export function encode64(arraybuffer) {
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const dv = new DataView(arraybuffer);
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let binaryString = "";
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for (let i = 0; i < arraybuffer.byteLength; i++) {
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binaryString += String.fromCharCode(dv.getUint8(i));
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}
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return binaryToAscii(binaryString);
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}
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/**
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* Decodes a base64 string into an arraybuffer
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* @param {string} string
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* @returns {ArrayBuffer}
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*/
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export function decode64(string) {
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const binaryString = asciiToBinary(string);
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const arraybuffer = new ArrayBuffer(binaryString.length);
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const dv = new DataView(arraybuffer);
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for (let i = 0; i < arraybuffer.byteLength; i++) {
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dv.setUint8(i, binaryString.charCodeAt(i));
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}
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return arraybuffer;
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}
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const KEY_STRING =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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/**
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* Substitute for atob since it's deprecated in node.
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* Does not do any input validation.
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*
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* @see https://github.com/jsdom/abab/blob/master/lib/atob.js
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*
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* @param {string} data
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* @returns {string}
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*/
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function asciiToBinary(data) {
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if (data.length % 4 === 0) {
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data = data.replace(/==?$/, "");
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}
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let output = "";
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let buffer = 0;
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let accumulatedBits = 0;
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for (let i = 0; i < data.length; i++) {
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buffer <<= 6;
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buffer |= KEY_STRING.indexOf(data[i]);
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accumulatedBits += 6;
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if (accumulatedBits === 24) {
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output += String.fromCharCode((buffer & 0xff0000) >> 16);
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output += String.fromCharCode((buffer & 0xff00) >> 8);
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output += String.fromCharCode(buffer & 0xff);
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buffer = accumulatedBits = 0;
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}
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}
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if (accumulatedBits === 12) {
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buffer >>= 4;
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output += String.fromCharCode(buffer);
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} else if (accumulatedBits === 18) {
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buffer >>= 2;
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output += String.fromCharCode((buffer & 0xff00) >> 8);
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output += String.fromCharCode(buffer & 0xff);
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}
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return output;
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}
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/**
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* Substitute for btoa since it's deprecated in node.
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* Does not do any input validation.
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*
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* @see https://github.com/jsdom/abab/blob/master/lib/btoa.js
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*
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* @param {string} str
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* @returns {string}
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*/
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function binaryToAscii(str) {
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let out = "";
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for (let i = 0; i < str.length; i += 3) {
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/** @type {[number, number, number, number]} */
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const groupsOfSix = [undefined, undefined, undefined, undefined];
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groupsOfSix[0] = str.charCodeAt(i) >> 2;
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groupsOfSix[1] = (str.charCodeAt(i) & 0x03) << 4;
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if (str.length > i + 1) {
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groupsOfSix[1] |= str.charCodeAt(i + 1) >> 4;
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groupsOfSix[2] = (str.charCodeAt(i + 1) & 0x0f) << 2;
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}
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if (str.length > i + 2) {
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groupsOfSix[2] |= str.charCodeAt(i + 2) >> 6;
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groupsOfSix[3] = str.charCodeAt(i + 2) & 0x3f;
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}
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for (let j = 0; j < groupsOfSix.length; j++) {
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if (typeof groupsOfSix[j] === "undefined") {
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out += "=";
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} else {
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out += KEY_STRING[groupsOfSix[j]];
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}
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}
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}
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return out;
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}
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