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websocket: don't use pooled buffer in mask pool #3357

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Merged
merged 4 commits into from
Jun 23, 2024
Merged

websocket: don't use pooled buffer in mask pool #3357

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97b5ba2
websocket: don't use pooled buffer in mask pool
tsctx Jun 22, 2024
abc6323
add test
tsctx Jun 22, 2024
cae53bc
fixup
tsctx Jun 22, 2024
071528e
fixup
tsctx Jun 22, 2024
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2 changes: 1 addition & 1 deletion lib/web/websocket/frame.js
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ try {
function generateMask () {
if (bufIdx === BUFFER_SIZE) {
bufIdx = 0
crypto.randomFillSync((buffer ??= Buffer.allocUnsafe(BUFFER_SIZE)), 0, BUFFER_SIZE)
crypto.randomFillSync((buffer ??= Buffer.allocUnsafeSlow(BUFFER_SIZE)), 0, BUFFER_SIZE)
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No problem, but with the current code, I have some concerns.

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I don't see them, unless we acess buffer.buffer anywhere

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If they access it, they can rewrite the mask, right?

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@tsctx tsctx Jun 22, 2024 •
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example:

import { WebSocket } from './index.js'

Buffer.poolSize = 16386 * 4

// any echo server url
const u = new WebSocket('ws://localhost:3000')

u.onmessage = (data) => {
  // The mask can be rewritten here.
  new Uint8Array(Buffer.allocUnsafe(1).buffer).fill(0)
  u.send('Hi')
}
u.onopen = () => {
  u.send('Hi')
}

}
return [buffer[bufIdx++], buffer[bufIdx++], buffer[bufIdx++], buffer[bufIdx++]]
}
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17 changes: 17 additions & 0 deletions test/websocket/frame.js
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,23 @@ const assert = require('node:assert')
const { WebsocketFrameSend } = require('../../lib/web/websocket/frame')
const { opcodes } = require('../../lib/web/websocket/constants')

// Always be above all tests.
test('Don not use pooled buffer in mask pool', () => {
const allocUnsafe = Buffer.allocUnsafe
let counter = 0
try {
Buffer.allocUnsafe = (n) => {
counter++
return allocUnsafe(n)
}
// create mask pool
new WebsocketFrameSend(Buffer.alloc(0)).createFrame(opcodes.BINARY)
assert.strictEqual(counter, 1)
} finally {
Buffer.allocUnsafe = allocUnsafe
}
})

test('Writing 16-bit frame length value at correct offset when buffer has a non-zero byteOffset', () => {
/*
When writing 16-bit frame lengths, a `DataView` was being used without setting a `byteOffset` into the buffer:
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