Class: Skinny::Websocket

Inherits:
EventMachine::Connection
  • Object
show all
Includes:
Callbacks, Thin::Logging
Defined in:
lib/skinny.rb

Overview

We need to be really careful not to throw an exception too high or we’ll kill the server.

Constant Summary collapse

MAX_BUFFER_LENGTH =

4mb is almost too generous, imho.

2 ** 32
GUID = 
"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
OPCODE_CONTINUATION = 
0x00
OPCODE_TEXT = 
0x01
OPCODE_BINARY = 
0x02
OPCODE_CLOSE = 
0x08
OPCODE_PING = 
0x09
OPCODE_PONG = 
0x0a

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Callbacks

included

Constructor Details

#initialize(env, options = {}) ⇒ Websocket

Returns a new instance of Websocket.

Raises:

  • (ArgumentError) 


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# File 'lib/skinny.rb', line 74

def initialize env, options={}
  @env = env.dup
  @buffer = ''

  @protocol = options.delete :protocol if options.has_key? :protocol
  [:on_open, :on_start, :on_handshake, :on_message, :on_error, :on_finish, :on_close].each do |name|
    send name, &options.delete(name) if options.has_key?(name)
  end
  raise ArgumentError, "Unknown options: #{options.inspect}" unless options.empty?
end

Instance Attribute Details

#env ⇒ Object (readonly)

Returns the value of attribute env.



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# File 'lib/skinny.rb', line 134

def env
  @env
end

#location ⇒ Object (readonly)

Returns the value of attribute location.



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# File 'lib/skinny.rb', line 134

def location
  @location
end

#origin ⇒ Object (readonly)

Returns the value of attribute origin.



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# File 'lib/skinny.rb', line 134

def origin
  @origin
end

#protocol ⇒ Object (readonly)

Returns the value of attribute protocol.



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# File 'lib/skinny.rb', line 134

def protocol
  @protocol
end

#version ⇒ Object (readonly)

Returns the value of attribute version.



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# File 'lib/skinny.rb', line 134

def version
  @version
end

Class Method Details

.from_env(env, options = {}) ⇒ Object

Create a new WebSocket from a Thin::Request environment



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# File 'lib/skinny.rb', line 63

def self.from_env env, options={}
  # Pull the connection out of the env
  thin_connection = env[Thin::Request::ASYNC_CALLBACK].receiver
  # Steal the IO
  fd = thin_connection.detach
  # EventMachine 1.0.0 needs this to be closable
  io = IO.for_fd(fd) unless fd.respond_to? :close
  # We have all the events now, muahaha
  EM.attach(io, self, env, options)
end

Instance Method Details

#challenge ⇒ Object 



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# File 'lib/skinny.rb', line 170

def challenge
  if hixie_75?
    nil
  elsif hixie_76?
    [key1, key2].pack("N*") + key3
  else
    key + GUID
  end
end

#challenge? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skinny.rb', line 166

def challenge?
  env.has_key? 'HTTP_SEC_WEBSOCKET_KEY1'
end

#challenge_response ⇒ Object 



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# File 'lib/skinny.rb', line 180

def challenge_response
  if hixie_75?
    nil
  elsif hixie_76?
    Digest::MD5.digest(challenge)
  else
    Base64.encode64(Digest::SHA1.digest(challenge)).strip
  end
end

#error!(message = nil, callback = true) ⇒ Object 



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# File 'lib/skinny.rb', line 408

def error! message=nil, callback=true
  log message unless message.nil?
  log_error # Logs the exception itself

  # Allow error messages to be handled, maybe
  # but only if this error was not caused by the error callback
  if callback
    EM.next_tick { callback(:on_error, self) rescue error! "Error in error callback", true }
  end

  # Try to finish and close nicely.
  EM.next_tick { finish! } unless [:finished, :closed, :error].include? @state

  # We're closed!
  @state = :error
end

#finish! ⇒ Object

Finish the connection read for closing



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# File 'lib/skinny.rb', line 384

def finish!
  if hixie_75? or hixie_76?
    send_data "\xff\x00"
  else
    send_frame OPCODE_CLOSE
  end

  EM.next_tick { callback(:on_finish, self) rescue error! "Error in finish callback" }
  EM.next_tick { close_connection_after_writing }

  @state = :finished
rescue
  error! "Error finishing WebSocket connection"
end

#handshake ⇒ Object

Generate the handshake



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# File 'lib/skinny.rb', line 191

def handshake
  "HTTP/1.1 101 Switching Protocols\r\n" <<
  "Connection: Upgrade\r\n" <<
  "Upgrade: WebSocket\r\n" <<
  if hixie_75?
    "WebSocket-Location: #{location}\r\n" <<
    "WebSocket-Origin: #{origin}\r\n"
  elsif hixie_76?
    "Sec-WebSocket-Location: #{location}\r\n" <<
    "Sec-WebSocket-Origin: #{origin}\r\n"
  else
    "Sec-WebSocket-Accept: #{challenge_response}\r\n"
  end <<
  (protocol ? "Sec-WebSocket-Protocol: #{protocol}\r\n" : "") <<
  "\r\n" <<
  (if hixie_76? then challenge_response else "" end)
end

#handshake! ⇒ Object 



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# File 'lib/skinny.rb', line 209

def handshake!
  if hixie_76?
    [key1, key2].each { |key| raise WebSocketProtocolError, "Invalid key: #{key}" if key >= 2**32 }
    raise WebSocketProtocolError, "Invalid challenge: #{key3}" if key3.length < 8
  end

  send_data handshake

  @state = :handshook

  EM.next_tick { callback :on_handshake, self rescue error! "Error in handshake callback" }
rescue
  error! "Error during WebSocket connection handshake"
end

#hixie_75? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skinny.rb', line 136

def hixie_75?
  @version == "hixie-75"
end

#hixie_76? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skinny.rb', line 140

def hixie_76?
  @version == "hixie-76"
end

#key ⇒ Object 



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# File 'lib/skinny.rb', line 151

def key
  @env['HTTP_SEC_WEBSOCKET_KEY']
end

#key3 ⇒ Object 



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# File 'lib/skinny.rb', line 162

def key3
  @key3 ||= @buffer.slice!(0...8)
end

#mask(payload, mask_key) ⇒ Object 



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# File 'lib/skinny.rb', line 232

def mask payload, mask_key
  payload.unpack("C*").map.with_index do |byte, index|
    byte ^ mask_key[index % 4]
  end.pack("C*")
end

#post_init ⇒ Object

Connection is now open



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# File 'lib/skinny.rb', line 86

def post_init
  EM.next_tick { callback :on_open, self rescue error! "Error in open callback" }
  @state = :open
rescue
  error! "Error opening connection"
end

#process_frame ⇒ Object 



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# File 'lib/skinny.rb', line 238

def process_frame
  if hixie_75? or hixie_76?
    if @buffer.length >= 1
      if @buffer[0].ord < 0x7f
        if ending = @buffer.index("\xff")
          frame = @buffer.slice! 0..ending
          message = frame[1..-2]

          EM.next_tick { receive_message message }

          # There might be more frames to process
          EM.next_tick { process_frame }
        elsif @buffer.length > MAX_BUFFER_LENGTH
          raise WebSocketProtocolError, "Maximum buffer length (#{MAX_BUFFER_LENGTH}) exceeded: #{@buffer.length}"
        end
      elsif @buffer[0] == "\xff"
        if @buffer.length > 1
          if @buffer[1] == "\x00"
            @buffer.slice! 0..1

            EM.next_tick { finish! }
          else
            raise WebSocketProtocolError, "Incorrect finish frame length: #{@buffer[1].inspect}"
          end
        end
      else
        raise WebSocketProtocolError, "Unknown frame type: #{@buffer[0].inspect}"
      end
    end
  else
    @frame_state ||= :opcode

    if @frame_state == :opcode
      return unless @buffer.length >= 2

      bytes = @buffer.slice!(0...2).unpack("C*")

      @opcode = bytes[0] & 0x0f
      @fin = (bytes[0] & 0x80) != 0
      @payload_length = bytes[1] & 0x7f
      @masked = (bytes[1] & 0x80) != 0

      return error! "Received unmasked data" unless @masked

      if @payload_length == 126
        @frame_state = :payload_2
      elsif @payload_length == 127
        @frame_state = :payload_8
      else
        @frame_state = :payload
      end

    elsif @frame_state == :payload_2
      return unless @buffer.length >= 2

      @payload_length = @buffer.slice!(0...2).unpack("n")[0]

      @frame_state = :mask

    elsif @frame_state == :payload_8
      return unless @buffer.length >= 8

      (high, low) = @buffer.slice!(0...8).unpack("NN")
      @payload_length = high * (2 ** 32) + low

      @frame_state = :mask

    elsif @frame_state == :mask
      return unless @buffer.length >= 4

      bytes = @buffer[(offset)...(offset += 4)]
      @mask_key = bytes.unpack("C*")

      @frame_state = :payload

    elsif @frame_state == :payload
      return unless @buffer.length >= @payload_length

      payload = @buffer.slice!(0...@payload_length)
      payload = mask(payload, @mask_key)

      if @opcode == OPCODE_TEXT
        message = payload.force_encoding("UTF-8") if payload.respond_to? :force_encoding
        EM.next_tick { receive_message payload }
      elsif @opcode == OPCODE_CLOSE
        EM.next_tick { finish! }
      else
        error! "Unsupported opcode: %d" % @opcode
      end

      @frame_state = nil
      @opcode = @fin = @payload_length = @masked = nil
    end
  end
rescue
  error! "Error while processing WebSocket frames"
end

#receive_data(data) ⇒ Object 



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# File 'lib/skinny.rb', line 224

def receive_data data
  @buffer << data

  EM.next_tick { process_frame } if @state == :handshook
rescue
  error! "Error while receiving WebSocket data"
end

#receive_message(message) ⇒ Object 



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# File 'lib/skinny.rb', line 336

def receive_message message
  EM.next_tick { callback :on_message, self, message rescue error! "Error in message callback" }
end

#response ⇒ Object Also known as: to_a

Return an async response – stops Thin doing anything with connection.



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# File 'lib/skinny.rb', line 94

def response
  Thin::Connection::AsyncResponse
end

#secure? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skinny.rb', line 144

def secure?
  @env['HTTPS'] == 'on' or
  # XXX: This could be faked... do we care?
  @env['HTTP_X_FORWARDED_PROTO'] == 'https' or
  @env['rack.url_scheme'] == 'https'
end

#send_frame(opcode, payload = "", masked = false) ⇒ Object

This is for post-hixie-76 versions only



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# File 'lib/skinny.rb', line 341

def send_frame opcode, payload="", masked=false
  payload = payload.dup.force_encoding("ASCII-8BIT") if payload.respond_to? :force_encoding
  payload_length = payload.bytesize

  # We don't support continuations (yet), so always send fin
  fin_byte = 0x80
  send_data [fin_byte | opcode].pack("C")

  # We shouldn't be sending mask, we're a server only
  masked_byte = masked ? 0x80 : 0x00

  if payload_length <= 125
    send_data [masked_byte | payload_length].pack("C")

  elsif payload_length < 2 ** 16
    send_data [masked_byte | 126].pack("C")
    send_data [payload_length].pack("n")

  else
    send_data [masked_byte | 127].pack("C")
    send_data [payload_length / (2 ** 32), payload_length % (2 ** 32)].pack("NN")
  end

  if payload_length
    if masked
      mask_key = Array.new(4) { rand(256) }.pack("C*")
      send_data mask_key
      payload = mask payload, mask_key
    end

    send_data payload
  end
end

#send_message(message) ⇒ Object 



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# File 'lib/skinny.rb', line 375

def send_message message
  if hixie_75? or hixie_76?
    send_data "\x00#{message}\xff"
  else
    send_frame OPCODE_TEXT, message
  end
end

#start! ⇒ Object

Start the websocket connection



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# File 'lib/skinny.rb', line 102

def start!
  # Steal any remaining data from rack.input
  @buffer = @env[Thin::Request::RACK_INPUT].read + @buffer

  # Remove references to Thin connection objects, freeing memory
  @env.delete Thin::Request::RACK_INPUT
  @env.delete Thin::Request::ASYNC_CALLBACK
  @env.delete Thin::Request::ASYNC_CLOSE

  # Figure out which version we're using
  @version = @env['HTTP_SEC_WEBSOCKET_VERSION']
  @version ||= "hixie-76" if @env.has_key?('HTTP_SEC_WEBSOCKET_KEY1') and @env.has_key?('HTTP_SEC_WEBSOCKET_KEY2')
  @version ||= "hixie-75"

  # Pull out the details we care about
  @origin ||= @env['HTTP_SEC_WEBSOCKET_ORIGIN'] || @env['HTTP_ORIGIN']
  @location ||= "ws#{secure? ? 's' : ''}://#{@env['HTTP_HOST']}#{@env['REQUEST_PATH']}"
  @protocol ||= @env['HTTP_SEC_WEBSOCKET_PROTOCOL'] || @env['HTTP_WEBSOCKET_PROTOCOL']

  EM.next_tick { callback :on_start, self rescue error! "Error in start callback" }

  # Queue up the actual handshake
  EM.next_tick method :handshake!

  @state = :started

  # Return self so we can be used as a response
  self
rescue
  error! "Error starting connection"
end

#unbind ⇒ Object

Make sure we call the on_close callbacks when the connection disappears



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# File 'lib/skinny.rb', line 401

def unbind
  EM.next_tick { callback(:on_close, self) rescue error! "Error in close callback" }
  @state = :closed
rescue
  error! "Error closing WebSocket connection"
end