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buffer: atob throw error when the input value is invalid #42662

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Merged
merged 6 commits into from
Apr 12, 2022
Merged

buffer: atob throw error when the input value is invalid #42662

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6f69681
buffer: atob throw error when the input value is invalid
austinkelleher Apr 8, 2022
08e4c75
buffer: simplify atob approach of disregarding whitespace
austinkelleher Apr 9, 2022
a85b856
buffer: switch to using InvalidCharacterError on encoding error
austinkelleher Apr 9, 2022
a5828d8
buffer: update character validation approach in atob
austinkelleher Apr 9, 2022
48d6cee
buffer: improve comments in atob function
austinkelleher Apr 9, 2022
5cee1b4
buffer: revive comment about code point length validation in atob
austinkelleher Apr 9, 2022
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28 changes: 24 additions & 4 deletions lib/buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1232,12 +1232,14 @@ function btoa(input) {
return buf.toString('base64');
}

// Refs: https://infra.spec.whatwg.org/#forgiving-base64-decode
const kForgivingBase64AllowedChars = [
const asciiWhitespaceCharacters = [
// ASCII whitespace
// Refs: https://infra.spec.whatwg.org/#ascii-whitespace
0x09, 0x0A, 0x0C, 0x0D, 0x20,
];

// Refs: https://infra.spec.whatwg.org/#forgiving-base64-decode
const kForgivingBase64AllowedChars = [
// Uppercase letters
...ArrayFrom({ length: 26 }, (_, i) => StringPrototypeCharCodeAt('A') + i),

Expand All @@ -1259,12 +1261,30 @@ function atob(input) {
if (arguments.length === 0) {
throw new ERR_MISSING_ARGS('input');
}

input = `${input}`;
let nonAsciiWhitespaceCharCount = 0;

for (let n = 0; n < input.length; n++) {
if (!ArrayPrototypeIncludes(kForgivingBase64AllowedChars,
StringPrototypeCharCodeAt(input, n)))
const char = StringPrototypeCharCodeAt(input, n);

if (ArrayPrototypeIncludes(kForgivingBase64AllowedChars, char)) {
nonAsciiWhitespaceCharCount++;
} else if (!ArrayPrototypeIncludes(asciiWhitespaceCharacters, char)) {
throw lazyDOMException('Invalid character', 'InvalidCharacterError');
}
}

// If data's code point length divides by 4 leaving a remainder of 1, then
// return failure.
//
// See #3 - https://infra.spec.whatwg.org/#forgiving-base64
if (nonAsciiWhitespaceCharCount % 4 === 1) {
throw lazyDOMException(
'The string to be decoded is not correctly encoded.',
'ValidationError');
}

return Buffer.from(input, 'base64').toString('latin1');
}

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14 changes: 14 additions & 0 deletions test/parallel/test-btoa-atob.js
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Original file line number Diff line number Diff line change
Expand Up @@ -15,3 +15,17 @@ throws(() => buffer.btoa(), /TypeError/);

strictEqual(atob(' '), '');
strictEqual(atob(' YW\tJ\njZA=\r= '), 'abcd');

strictEqual(atob(null), '\x9Eée');
strictEqual(atob(NaN), '5£');
strictEqual(atob(Infinity), '"wâ\x9E+r');
strictEqual(atob(true), '¶»\x9E');
strictEqual(atob(1234), '×mø');
strictEqual(atob([]), '');
strictEqual(atob({ toString: () => '' }), '');
strictEqual(atob({ [Symbol.toPrimitive]: () => '' }), '');

throws(() => atob(), /ERR_MISSING_ARGS/);
throws(() => atob(Symbol()), /TypeError/);
[undefined, false, () => {}, 0, 1, 0n, 1n, -Infinity, [1], {}].forEach((value) =>
throws(() => atob(value), { constructor: DOMException }));