Class: PDTP::LengthPrefixProtocol::Prefix

Inherits:
Object
  • Object
show all
Defined in:
lib/pdtp/common/length_prefix_protocol.rb

Overview

Class for processing size prefixes in packet frames

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size = 2) ⇒ Prefix

Returns a new instance of Prefix.



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 33

def initialize(size = 2)
  unless size == 2 or size == 4
    raise ArgumentError, 'only 2 or 4 byte prefixes are supported' 
  end
  
  @size = size
  reset!
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 31

def data
  @data
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 31

def size
  @size
end

Instance Method Details

#append(data) ⇒ Object

Append data to the prefix and return any extra



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 48

def append(data)
  toread = @size - @read
  new_data = data[0..(toread - 1)]
  
  @data << new_data        
  @read += new_data.size
  return nil unless @read == @size
  
  @payload_length = @data.unpack(@size == 2 ? 'n' : 'N').first
  result = data[toread..data.length]
  
  return nil if result.nil? or result.empty?
  result
end

#payload_length ⇒ Object

Length of the payload extracted from the prefix

Raises:

  • (RuntimeError) 


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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 64

def payload_length
  raise RuntimeError, 'payload_length called before prefix extracted' unless read?
  @payload_length
end

#read? ⇒ Boolean

Has the entire prefix been read yet?

Returns:

  • (Boolean) 


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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 43

def read?
  @size == @read
end

#reset! ⇒ Object 



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 69

def reset!
  @payload_length = nil
  @read = 0
  @data = ''        
end