Module: Protocol::WebSocket::Extension::Compression

Defined in:
lib/protocol/websocket/extension/compression.rb,
lib/protocol/websocket/extension/compression/deflate.rb,
lib/protocol/websocket/extension/compression/inflate.rb,
lib/protocol/websocket/extension/compression/constants.rb

Overview

Provides support for the permessage-deflate extension.

Defined Under Namespace

Classes: Deflate, Inflate

Constant Summary collapse

NAME = 
"permessage-deflate"
MINIMUM_WINDOW_BITS =

Zlib is not capable of handling < 9 window bits.

9

Class Method Summary collapse

Class Method Details

.accept(arguments, **options) ⇒ Object

Accept on the client, the negotiated server response.



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# File 'lib/protocol/websocket/extension/compression.rb', line 94

def self.accept(arguments, **options)
  arguments.each do |key, value|
    case key
    when "server_no_context_takeover"
      options[:server_no_context_takeover] = true
    when "client_no_context_takeover"
      options[:client_no_context_takeover] = true
    when "server_max_window_bits"
      options[:server_max_window_bits] = Integer(value || 15)
    when "client_max_window_bits"
      options[:client_max_window_bits] = Integer(value || 15)
    else
      raise ArgumentError, "Unknown option: #{key}!"
    end
  end
  
  return options
end

.client(connection, **options) ⇒ Object 



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# File 'lib/protocol/websocket/extension/compression.rb', line 114

def self.client(connection, **options)
  connection.reserve!(Frame::RSV1)
  
  connection.reader = Inflate.client(connection.reader, **options)
  connection.writer = Deflate.client(connection.writer, **options)
end

.negotiate(arguments, **options) ⇒ Object

Negotiate on the server a response to client based on the incoming client offer.



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# File 'lib/protocol/websocket/extension/compression.rb', line 53

def self.negotiate(arguments, **options)
  header = [NAME]
  
  arguments.each do |key, value|
    case key
    when "server_no_context_takeover"
      options[:server_no_context_takeover] = true
      header << key
    when "client_no_context_takeover"
      options[:client_no_context_takeover] = true
      header << key
    when "server_max_window_bits"
      value = Integer(value || 15)
      value = MINIMUM_WINDOW_BITS if value < MINIMUM_WINDOW_BITS
      options[:server_max_window_bits] = value
      header << "server_max_window_bits=#{value}"
    when "client_max_window_bits"
      value = Integer(value || 15)
      value = MINIMUM_WINDOW_BITS if value < MINIMUM_WINDOW_BITS
      options[:client_max_window_bits] = value
      header << "client_max_window_bits=#{value}"
    else
      raise ArgumentError, "Unknown option: #{key}!"
    end
  end
  
  # The header which represents the final accepted/negotiated configuration.
  return header, options
end

.offer(client_max_window_bits: true, server_max_window_bits: true, client_no_context_takeover: false, server_no_context_takeover: false) ⇒ Object

Client offer to server, construct a list of requested compression parameters suitable for the ‘Sec-WebSocket-Extensions` header.



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# File 'lib/protocol/websocket/extension/compression.rb', line 17

def self.offer(client_max_window_bits: true, server_max_window_bits: true, client_no_context_takeover: false, server_no_context_takeover: false)
  
  header = [NAME]
  
  case client_max_window_bits
  when 8..15
    header << "client_max_window_bits=#{client_max_window_bits}"
  when true
    header << "client_max_window_bits"
  else
    raise ArgumentError, "Invalid local maximum window bits!"
  end
  
  if client_no_context_takeover
    header << "client_no_context_takeover"
  end
  
  case server_max_window_bits
  when 8..15
    header << "server_max_window_bits=#{server_max_window_bits}"
  when true
    # Default (unspecified) to the server maximum window bits.
  else
    raise ArgumentError, "Invalid remote maximum window bits!"
  end
  
  if server_no_context_takeover
    header << "server_no_context_takeover"
  end
  
  return header
end

.server(connection, **options) ⇒ Object 



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# File 'lib/protocol/websocket/extension/compression.rb', line 84

def self.server(connection, **options)
  connection.reserve!(Frame::RSV1)
  
  connection.reader = Inflate.server(connection.reader, **options)
  connection.writer = Deflate.server(connection.writer, **options)
end