79 lines
1.9 KiB
Markdown
79 lines
1.9 KiB
Markdown
# bufferutil
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[](https://www.npmjs.com/package/bufferutil)
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[](https://github.com/websockets/bufferutil/actions?query=workflow%3ACI+branch%3Amaster)
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`bufferutil` is what makes `ws` fast. It provides some utilities to efficiently
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perform some operations such as masking and unmasking the data payload of
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WebSocket frames.
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## Installation
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```
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npm install bufferutil --save-optional
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```
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The `--save-optional` flag tells npm to save the package in your package.json
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under the
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[`optionalDependencies`](https://docs.npmjs.com/files/package.json#optionaldependencies)
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key.
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## API
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The module exports two functions.
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### `bufferUtil.mask(source, mask, output, offset, length)`
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Masks a buffer using the given masking-key as specified by the WebSocket
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protocol.
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#### Arguments
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- `source` - The buffer to mask.
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- `mask` - A buffer representing the masking-key.
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- `output` - The buffer where to store the result.
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- `offset` - The offset at which to start writing.
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- `length` - The number of bytes to mask.
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#### Example
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```js
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'use strict';
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const bufferUtil = require('bufferutil');
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const crypto = require('crypto');
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const source = crypto.randomBytes(10);
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const mask = crypto.randomBytes(4);
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bufferUtil.mask(source, mask, source, 0, source.length);
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```
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### `bufferUtil.unmask(buffer, mask)`
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Unmasks a buffer using the given masking-key as specified by the WebSocket
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protocol.
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#### Arguments
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- `buffer` - The buffer to unmask.
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- `mask` - A buffer representing the masking-key.
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#### Example
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```js
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'use strict';
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const bufferUtil = require('bufferutil');
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const crypto = require('crypto');
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const buffer = crypto.randomBytes(10);
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const mask = crypto.randomBytes(4);
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bufferUtil.unmask(buffer, mask);
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```
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## License
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[MIT](LICENSE)
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