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

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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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26 changes: 23 additions & 3 deletions lib/buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ const {
ArrayFrom,
ArrayIsArray,
ArrayPrototypeForEach,
ArrayPrototypeIncludes,
ArrayPrototypeIndexOf,
MathFloor,
MathMin,
MathTrunc,
Expand Down Expand Up @@ -1259,12 +1259,32 @@ 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 index = ArrayPrototypeIndexOf(
kForgivingBase64AllowedChars,
StringPrototypeCharCodeAt(input, n));

if (index > 4) { // The first five char are ASCII whitespace.
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nonAsciiWhitespaceCharCount++;
} else if (index === -1) {
throw lazyDOMException('Invalid character', 'InvalidCharacterError');
}
}

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

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

Expand Down
24 changes: 23 additions & 1 deletion test/parallel/test-btoa-atob.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,4 +14,26 @@ throws(() => buffer.atob(), /TypeError/);
throws(() => buffer.btoa(), /TypeError/);

strictEqual(atob(' '), '');
strictEqual(atob(' YW\tJ\njZA=\r= '), 'abcd');
strictEqual(atob(' Y\fW\tJ\njZ A=\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(Symbol()), /TypeError/);
[
undefined, false, () => {}, {}, [1],
0, 1, 0n, 1n, -Infinity,
'a', 'a\n\n\n', '\ra\r\r', ' a ', '\t\t\ta', 'a\f\f\f', '\ta\r \n\f',
].forEach((value) =>
// See #2 - https://html.spec.whatwg.org/multipage/webappapis.html#dom-atob
throws(() => atob(value), {
constructor: DOMException,
name: 'InvalidCharacterError',
code: 5,
}));