Class: DNSSD::TextRecord

Inherits:
Hash
  • Object
show all
Defined in:
lib/dnssd/text_record.rb

Overview

DNSSD::TextRecord is a Hash delegate that can encode its contents for DNSSD.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(text_record = nil) ⇒ TextRecord

Creates a new TextRecord decoding an encoded text_record if given or from a given Hash.

DNSSD::TextRecord.new "\003k=v"

or

DNSSD::TextRecord.new 'k' => 'v'



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# File 'lib/dnssd/text_record.rb', line 43

def initialize(text_record = nil)
  super case text_record
        when Hash then
          text_record.dup
        when String then
          decode(text_record.dup)
        else
          Hash.new
        end
end

Class Method Details

.decode(text_record) ⇒ Object 



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# File 'lib/dnssd/text_record.rb', line 7

def self.decode text_record
  record = {}

  tr = text_record.unpack 'C*'

  until tr.empty? do
    size  = tr.shift

    next if size.zero?

    raise ArgumentError, 'ran out of data in text record' if tr.length < size

    entry = tr.shift(size).pack('C*')

    raise ArgumentError, 'key not found' unless entry =~ /^[^=]/

    key, value = entry.split '=', 2

    next unless key

    record[key] = value
  end

  new record
end

Instance Method Details

#decode(text_record) ⇒ Object

Decodes text_record and returns a Hash



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# File 'lib/dnssd/text_record.rb', line 57

def decode(text_record)
  self.class.decode text_record
end

#encode ⇒ Object

Encodes this TextRecord. A key value pair must be less than 255 bytes in length. Keys longer than 14 bytes may not be compatible with all clients.



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# File 'lib/dnssd/text_record.rb', line 66

def encode
  sort.map do |key, value|
    key = key.to_s

    raise DNSSD::Error, "empty key" if key.empty?
    raise DNSSD::Error, "key '#{key}' contains =" if key =~ /=/

    record = value ? [key, value.to_s].join('=') : key

    raise DNSSD::Error, "key value pair at '#{key}' too large to encode" if
      record.length > 255

    "#{record.length.chr}#{record}"
  end.join ''
end