Implement ServerSession, passes Autobahn 12.1.*.

.gitignore

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+Gemfile.lock
+*.gem

Gemfile

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+source 'https://rubygems.org'
+gemspec

lib/permessage_deflate.rb

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+require 'zlib'
+
+class PermessageDeflate
+  VALID_PARAMS = [
+    'server_no_context_takeover',
+    'client_no_context_takeover',
+    'server_max_window_bits',
+    'client_max_window_bits'
+  ]
+
+  DEFAULT_MAX_WINDOW_BITS = 15
+  VALID_WINDOW_BITS = [8, 9, 10, 11, 12, 13, 14, 15]
+
+  root = File.expand_path('..', __FILE__)
+  require root + '/permessage_deflate/session'
+  require root + '/permessage_deflate/server_session'
+
+  module Extension
+    define_method(:name) { 'permessage-deflate' }
+    define_method(:type) { 'permessage' }
+    define_method(:rsv1) { true  }
+    define_method(:rsv2) { false }
+    define_method(:rsv3) { false }
+
+    def create_server_session(offers)
+      offers.each do |offer|
+        return ServerSession.new(offer) if ServerSession.valid_params?(offer)
+      end
+    end
+  end
+
+  extend Extension
+end

lib/permessage_deflate/server_session.rb

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+class PermessageDeflate
+  class ServerSession < Session
+
+    def self.valid_params?(params)
+      true # TODO
+    end
+
+    def initialize(params)
+      super()
+      @params = params
+    end
+
+    def generate_response
+      params = {}
+
+      # https://tools.ietf.org/html/draft-ietf-hybi-permessage-compression#section-8.1.1.1
+      if @params['server_no_context_takeover']
+        params['server_no_context_takeover'] = true
+      end
+
+      # https://tools.ietf.org/html/draft-ietf-hybi-permessage-compression#section-8.1.1.2
+      if @params['client_no_context_takeover']
+        params['client_no_context_takeover'] = true
+      end
+
+      # https://tools.ietf.org/html/draft-ietf-hybi-permessage-compression#section-8.1.2.1
+      if server_max = @params['server_max_window_bits']
+        params['server_max_window_bits'] = [server_max, DEFAULT_MAX_WINDOW_BITS].min
+      end
+
+      # https://tools.ietf.org/html/draft-ietf-hybi-permessage-compression#section-8.1.2.2
+      if client_max = @params['client_max_window_bits']
+        client_max = DEFAULT_MAX_WINDOW_BITS if client_max == true
+        params['client_max_window_bits'] = [client_max, DEFAULT_MAX_WINDOW_BITS].min
+      end
+
+      @own_context_takeover = !params['server_no_context_takeover']
+      @own_window_bits = params['server_max_window_bits'] || DEFAULT_MAX_WINDOW_BITS
+
+      @peer_context_takeover = !params['client_no_context_takeover']
+      @peer_window_bits = params['client_max_window_bits'] || DEFAULT_MAX_WINDOW_BITS
+
+      params
+    end
+
+  end
+end

lib/permessage_deflate/session.rb

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+class PermessageDeflate
+  class Session
+
+    MESSAGE_OPCODES = [1, 2]
+
+    def valid_frame_rsv(frame)
+      if MESSAGE_OPCODES.include?(frame.opcode)
+        {:rsv1 => true, :rsv2 => false, :rsv3 => false}
+      else
+        {:rsv1 => false, :rsv2 => false, :rsv3 => false}
+      end
+    end
+
+    def process_incoming_message(message)
+      compressed = message.frames.first.rsv1
+      return message unless compressed
+
+      inflate = get_inflate
+
+      message.data = inflate.inflate(message.data) +
+                     inflate.inflate([0x00, 0x00, 0xff, 0xff].pack('C*'))
+
+      inflate.close unless @inflate
+      message
+    end
+
+    def process_outgoing_message(message)
+      deflate = get_deflate
+      payload = (deflate.deflate(message.data) + deflate.flush)[0...-4]
+      frame   = message.frames.first
+
+      deflate.close unless @deflate
+
+      frame.final   = true
+      frame.rsv1    = true
+      frame.length  = payload.bytesize
+      frame.payload = payload
+
+      message.data   = payload
+      message.frames = [frame]
+
+      message
+    end
+
+    def close
+      @inflate.close if @inflate
+      @inflate = nil
+
+      @deflate.close if @deflate
+      @deflate = nil
+    end
+
+  private
+
+    def f(string)
+      bytes = string.bytes.map { |b| b.to_s(16).rjust(2, '0') }
+      "<#{string.encoding}: #{bytes * ' '}>"
+    end
+
+    def get_inflate
+      return @inflate if @inflate
+      inflate = Zlib::Inflate.new(-@peer_window_bits)
+      @inflate = inflate if @peer_context_takeover
+      inflate
+    end
+
+    def get_deflate
+      return @deflate if @deflate
+      deflate = Zlib::Deflate.new(Zlib::DEFAULT_COMPRESSION, -@own_window_bits)
+      @deflate = deflate if @own_context_takeover
+      deflate
+    end
+
+  end
+end

permessage-deflate.gemspec

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+Gem::Specification.new do |s|
+  s.name              = 'permessage-deflate'
+  s.version           = '0.1.0'
+  s.summary           = 'Per-message DEFLATE compression extension for WebSocket connections'
+  s.author            = 'James Coglan'
+  s.email             = 'jcoglan@gmail.com'
+  s.homepage          = 'http://github.com/faye/permessage-deflate-ruby'
+  s.license           = 'MIT'
+
+  s.extra_rdoc_files  = %w[README.md]
+  s.rdoc_options      = %w[--main README.md --markup markdown]
+  s.require_paths     = %w[lib]
+
+  s.files = %w[README.md] + Dir.glob('lib/**/*.rb')
+
+  s.add_development_dependency 'rspec'
+end