92 lines
2.7 KiB
Markdown
92 lines
2.7 KiB
Markdown
# dns-txt
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Encode or decode the RDATA field in multicast DNS TXT records. For use
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with DNS-Based Service Discovery. For details see [RFC
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6763](https://tools.ietf.org/html/rfc6763).
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[](https://travis-ci.org/watson/dns-txt)
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[](https://github.com/feross/standard)
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[](https://github.com/mafintosh/abstract-encoding)
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## Installation
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```
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npm install dns-txt
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```
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## Usage
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```js
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var txt = require('dns-txt')()
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var obj = {
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foo: 1,
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bar: 2
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}
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var enc = txt.encode(obj) // <Buffer 05 66 6f 6f 3d 31 05 62 61 72 3d 32>
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txt.decode(enc) // { foo: '1', bar: '2' }
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```
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## API
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The encoder and decoder conforms to [RFC 6763](https://tools.ietf.org/html/rfc6763).
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### Initialize
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The module exposes a constructor function which can be called with an
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optional options object:
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```js
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var txt = require('dns-txt')({ binary: true })
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```
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The options are:
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- `binary` - If set to `true` all values will be returned as `Buffer`
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objects. The default behavior is to turn all values into strings. But
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according to the RFC the values can be any binary data. If you expect
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binary data, use this option.
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#### `txt.encode(obj, [buffer], [offset])`
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Takes a key/value object and returns a buffer with the encoded TXT
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record. If a buffer is passed as the second argument the object should
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be encoded into that buffer. Otherwise a new buffer should be allocated
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If an offset is passed as the third argument the object should be
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encoded at that byte offset. The byte offset defaults to `0`.
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This module does not actively validate the key/value pairs, but keep the
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following in rules in mind:
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- To be RFC compliant, each key should conform with the rules as
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specified in [section
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6.4](https://tools.ietf.org/html/rfc6763#section-6.4).
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- To be RFC compliant, each value should conform with the rules as
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specified in [section
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6.5](https://tools.ietf.org/html/rfc6763#section-6.5).
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After encoding `txt.encode.bytes` is set to the amount of bytes used to
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encode the object.
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#### `txt.decode(buffer, [offset], [length])`
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Takes a buffer and returns a decoded key/value object. If an offset is
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passed as the second argument the object should be decoded from that
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byte offset. The byte offset defaults to `0`. Note that all keys will be
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lowercased and all values will be Buffer objects.
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After decoding `txt.decode.bytes` is set to the amount of bytes used to
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decode the object.
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#### `txt.encodingLength(obj)`
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Takes a single key/value object and returns the number of bytes that the given
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object would require if encoded.
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## License
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MIT
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