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atob.js
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Range check for b64 Alphabet

This commit is contained in:
Michael Theos 2021-03-12 00:26:12 +11:00
parent 47351c126d
commit ca3678cddb
1 changed files with 17 additions and 4 deletions
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21
node-atob.js
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@ -1,11 +1,24 @@
"use strict";
const b64Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='
// var b64Alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
function toCharCode(ch) {
return ch.charCodeAt(0);
}
function isValidB64Char(charCode) {
return charCode >= toCharCode('A') && charCode <= toCharCode('Z')
|| charCode >= toCharCode('a') && charCode <= toCharCode('z')
|| charCode >= toCharCode('0') && charCode <= toCharCode('9')
|| charCode === toCharCode('+')
|| charCode === toCharCode('/')
|| charCode === toCharCode('=');
}
function atob(str) {
for (const ch of str)
if (!b64Alphabet.includes(ch))
throw new Error(`Invalid character '${ch}' in base64 String`);
for (var idx in str)
if (!isValidB64Char(str.charCodeAt(idx)))
throw new Error('Invalid character ' + str.charAt(idx) + ' in base64 String');
return Buffer.from(str, 'base64').toString('binary');
}