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133 lines
4.7 KiB
JavaScript
133 lines
4.7 KiB
JavaScript
4 years ago
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/*
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MIT License
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Copyright (c) 2020 Egor Nepomnyaschih
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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/*
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// This constant can also be computed with the following algorithm:
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const base64abc = [],
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A = "A".charCodeAt(0),
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a = "a".charCodeAt(0),
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n = "0".charCodeAt(0);
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for (let i = 0; i < 26; ++i) {
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base64abc.push(String.fromCharCode(A + i));
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}
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for (let i = 0; i < 26; ++i) {
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base64abc.push(String.fromCharCode(a + i));
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}
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for (let i = 0; i < 10; ++i) {
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base64abc.push(String.fromCharCode(n + i));
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}
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base64abc.push("+");
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base64abc.push("/");
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*/
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const base64abc = [
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"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
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"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
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"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
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"n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
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"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "+", "/"
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];
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/*
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// This constant can also be computed with the following algorithm:
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const l = 256, base64codes = new Uint8Array(l);
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for (let i = 0; i < l; ++i) {
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base64codes[i] = 255; // invalid character
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}
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base64abc.forEach((char, index) => {
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base64codes[char.charCodeAt(0)] = index;
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});
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base64codes["=".charCodeAt(0)] = 0; // ignored anyway, so we just need to prevent an error
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*/
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const base64codes = [
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 0, 255, 255,
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255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
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255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
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];
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function getBase64Code(charCode) {
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if (charCode >= base64codes.length) {
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throw new Error("Unable to parse base64 string.");
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}
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const code = base64codes[charCode];
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if (code === 255) {
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throw new Error("Unable to parse base64 string.");
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}
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return code;
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}
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export function bytesToBase64(bytes) {
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let result = '', i, l = bytes.length;
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for (i = 2; i < l; i += 3) {
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result += base64abc[bytes[i - 2] >> 2];
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result += base64abc[((bytes[i - 2] & 0x03) << 4) | (bytes[i - 1] >> 4)];
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result += base64abc[((bytes[i - 1] & 0x0F) << 2) | (bytes[i] >> 6)];
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result += base64abc[bytes[i] & 0x3F];
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}
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if (i === l + 1) { // 1 octet yet to write
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result += base64abc[bytes[i - 2] >> 2];
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result += base64abc[(bytes[i - 2] & 0x03) << 4];
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result += "==";
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}
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if (i === l) { // 2 octets yet to write
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result += base64abc[bytes[i - 2] >> 2];
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result += base64abc[((bytes[i - 2] & 0x03) << 4) | (bytes[i - 1] >> 4)];
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result += base64abc[(bytes[i - 1] & 0x0F) << 2];
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result += "=";
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}
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return result;
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}
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export function base64ToBytes(str) {
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if (str.length % 4 !== 0) {
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throw new Error("Unable to parse base64 string.");
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}
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const index = str.indexOf("=");
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if (index !== -1 && index < str.length - 2) {
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throw new Error("Unable to parse base64 string.");
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}
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let missingOctets = str.endsWith("==") ? 2 : str.endsWith("=") ? 1 : 0,
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n = str.length,
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result = new Uint8Array(3 * (n / 4)),
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buffer;
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for (let i = 0, j = 0; i < n; i += 4, j += 3) {
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buffer =
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getBase64Code(str.charCodeAt(i)) << 18 |
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getBase64Code(str.charCodeAt(i + 1)) << 12 |
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getBase64Code(str.charCodeAt(i + 2)) << 6 |
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getBase64Code(str.charCodeAt(i + 3));
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result[j] = buffer >> 16;
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result[j + 1] = (buffer >> 8) & 0xFF;
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result[j + 2] = buffer & 0xFF;
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}
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return result.subarray(0, result.length - missingOctets);
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}
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export function base64encode(str, encoder = new TextEncoder()) {
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return bytesToBase64(encoder.encode(str));
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}
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export function base64decode(str, decoder = new TextDecoder()) {
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return decoder.decode(base64ToBytes(str));
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}
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