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Fix fromHex invalid hex behavior #303

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merged 3 commits into from
Oct 11, 2023
Merged

Fix fromHex invalid hex behavior #303

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a4e7258
Fix: NodeJS Buffer behavior differed, also perf improvement on hex pa…
junderw Oct 16, 2021
ddd37ec
Add myself to AUTHORS.md with the script
junderw Oct 16, 2021
d2d1978
prefer constant table
dcousens Oct 11, 2023
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1 change: 1 addition & 0 deletions AUTHORS.md
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Original file line number Diff line number Diff line change
Expand Up @@ -69,5 +69,6 @@
- jkkang ([email protected])
- Deklan Webster ([email protected])
- Martin Heidegger ([email protected])
- junderw ([email protected])

#### Generated by bin/update-authors.sh.
35 changes: 32 additions & 3 deletions index.js
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Expand Up @@ -844,9 +844,12 @@ function hexWrite (buf, string, offset, length) {
}
let i
for (i = 0; i < length; ++i) {
const parsed = parseInt(string.substr(i * 2, 2), 16)
if (numberIsNaN(parsed)) return i
buf[offset + i] = parsed
const a = hexCharValueTable[string[i * 2]]
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const b = hexCharValueTable[string[i * 2 + 1]]
if (a === undefined || b === undefined) {
return i
}
buf[offset + i] = a << 4 | b
}
return i
}
Expand Down Expand Up @@ -2098,6 +2101,32 @@ const hexSliceLookupTable = (function () {
return table
})()

// hex lookup table for Buffer.from(x, 'hex')
const hexCharValueTable = {
'0': 0,
'1': 1,
'2': 2,
'3': 3,
'4': 4,
'5': 5,
'6': 6,
'7': 7,
'8': 8,
'9': 9,
a: 10,
b: 11,
c: 12,
d: 13,
e: 14,
f: 15,
A: 10,
B: 11,
C: 12,
D: 13,
E: 14,
F: 15
}

// Return not function with Error if BigInt not supported
function defineBigIntMethod (fn) {
return typeof BigInt === 'undefined' ? BufferBigIntNotDefined : fn
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6 changes: 6 additions & 0 deletions test/node/test-buffer-badhex.js
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Expand Up @@ -14,6 +14,12 @@ const assert = require('assert');
assert.strictEqual(buf.write('abcdef01', 0, 'hex'), 4);
assert.deepStrictEqual(buf, new Buffer([0xab, 0xcd, 0xef, 0x01]));
assert.strictEqual(buf.toString('hex'), 'abcdef01');
// Node Buffer behavior check
// > Buffer.from('abc def01','hex')
// <Buffer ab>
assert.strictEqual(buf.write('abc def01', 0, 'hex'), 1);
assert.deepStrictEqual(buf, new Buffer([0xab]));
assert.strictEqual(buf.toString('hex'), 'ab');
Comment on lines +21 to +22
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buf here is a 4 bytes long buffer, so these asserts can never succeed? Did you try this locally? 🤔

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buf should NOT be a 4 byte buffer. That's the point.

If it is a 4 byte buffer, than the code is broken.

a non-hex character should end the hex parsing and only the 2-hex pairs up until the first non-hex is output as a Buffer.

in this case, [0xab]

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But you are doing .write on an already existing Buffer that is 4 bytes long. write cannot truncate the length of the buffer.

With my updated tests it checks that write only wrote 1 byte, and that it left the three bytes after as 00 00 00.


const copy = Buffer.from(buf.toString('hex'), 'hex');
assert.strictEqual(buf.toString('hex'), copy.toString('hex'));
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