Class: Protocol::WebSocket::Frame

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/protocol/websocket/frame.rb

Constant Summary collapse

RSV1 = 
0b0100
RSV2 = 
0b0010
RSV3 = 
0b0001
RESERVED = 
RSV1 | RSV2 | RSV3
OPCODE = 
0

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(finished = true, payload = nil, flags: 0, opcode: self.class::OPCODE, mask: false) ⇒ Frame

Returns a new instance of Frame.



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# File 'lib/protocol/websocket/frame.rb', line 24

def initialize(finished = true, payload = nil, flags: 0, opcode: self.class::OPCODE, mask: false)
	if mask == true
		mask = SecureRandom.bytes(4)
	end
	
	@finished = finished
	@flags = flags
	@opcode = opcode
	@mask = mask
	@length = payload&.bytesize
	@payload = payload
end

Instance Attribute Details

#finished ⇒ Object

The generic frame header uses the following binary representation:

0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

-------------------------——————————-+ |F|R|R|R| opcode|M| Payload len | Extended payload length | |I|S|S|S| (4) |A| (7) | (16/64) | |N|V|V|V| |S| | (if payload len==126/127) | | |1|2|3| |K| | | ------------------------- - - - - - - - - - - - - - - - + | Extended payload length continued, if payload len == 127 | + - - - - - - - - - - - - - - - ------------------------------- | |Masking-key, if MASK set to 1 | -------------------------------——————————-+ | Masking-key (continued) | Payload Data | ——————————– - - - - - - - - - - - - - - - : Payload Data continued … : + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + | Payload Data continued … | ---------------------------------------------------------------



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# File 'lib/protocol/websocket/frame.rb', line 82

def finished
  @finished
end

#flags ⇒ Object

Returns the value of attribute flags.



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# File 'lib/protocol/websocket/frame.rb', line 83

def flags
  @flags
end

#length ⇒ Object

Returns the value of attribute length.



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# File 'lib/protocol/websocket/frame.rb', line 86

def length
  @length
end

#mask ⇒ Object

Returns the value of attribute mask.



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# File 'lib/protocol/websocket/frame.rb', line 85

def mask
  @mask
end

#opcode ⇒ Object

Returns the value of attribute opcode.



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

def opcode
  @opcode
end

#payload ⇒ Object

Returns the value of attribute payload.



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# File 'lib/protocol/websocket/frame.rb', line 87

def payload
  @payload
end

Class Method Details

.parse_header(buffer) ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 143

def self.parse_header(buffer)
	byte = buffer.unpack("C").first
	
	finished = (byte & 0b1000_0000 != 0)
	flags = (byte & 0b0111_0000) >> 4
	opcode = byte & 0b0000_1111
	
	if (0x3 .. 0x7).include?(opcode)
		raise ProtocolError, "Non-control opcode = #{opcode} is reserved!"
	elsif (0xB .. 0xF).include?(opcode)
		raise ProtocolError, "Control opcode = #{opcode} is reserved!"
	end
	
	return finished, flags, opcode
end

.read(finished, flags, opcode, stream, maximum_frame_size) ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 159

def self.read(finished, flags, opcode, stream, maximum_frame_size)
	buffer = stream.read(1) or raise EOFError, "Could not read header!"
	byte = buffer.unpack("C").first
	
	mask = (byte & 0b1000_0000 != 0)
	length = byte & 0b0111_1111
	
	if opcode & 0x8 != 0
		if length > 125
			raise ProtocolError, "Invalid control frame payload length: #{length} > 125!"
		elsif !finished
			raise ProtocolError, "Fragmented control frame!"
		end
	end
	
	if length == 126
		buffer = stream.read(2) or raise EOFError, "Could not read length!"
		length = buffer.unpack('n').first
	elsif length == 127
		buffer = stream.read(8) or raise EOFError, "Could not read length!"
		length = buffer.unpack('Q>').first
	end
	
	if length > maximum_frame_size
		raise ProtocolError, "Invalid payload length: #{@length} > #{maximum_frame_size}!"
	end
	
	if mask
		mask = stream.read(4) or raise EOFError, "Could not read mask!"
	end
	
	payload = stream.read(length) or raise EOFError, "Could not read payload!"
	
	if payload.bytesize != length
		raise EOFError, "Incorrect payload length: #{@length} != #{payload.bytesize}!"
	end
	
	return self.new(finished, payload, flags: flags, opcode: opcode, mask: mask)
end

Instance Method Details

#<=>(other) ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 37

def <=> other
	to_ary <=> other.to_ary
end

#apply(connection) ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 139

def apply(connection)
	connection.receive_frame(self)
end

#continued? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/websocket/frame.rb', line 57

def continued?
	@finished == false
end

#control? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/websocket/frame.rb', line 45

def control?
	@opcode & 0x8 != 0
end

#data? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol/websocket/frame.rb', line 49

def data?
	false
end

#finished? ⇒ Boolean

Returns:

  • (Boolean) 


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

def finished?
	@finished == true
end

#pack(data = "") ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 113

def pack(data = "")
	length = data.bytesize
	
	if length.bit_length > 63
		raise ProtocolError, "Frame length #{@length} bigger than allowed maximum!"
	end
	
	if @mask
		@payload = mask_xor(data, mask)
		@length = length
	else
		@payload = data
		@length = length
	end
	
	return self
end

#to_ary ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 41

def to_ary
	[@finished, @flags, @opcode, @mask, @length, @payload]
end

#unpack ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 131

def unpack
	if @mask and !@payload.empty?
		return mask_xor(@payload, @mask)
	else
		return @payload
	end
end

#write(stream) ⇒ Object 



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# File 'lib/protocol/websocket/frame.rb', line 199

def write(stream)
	buffer = String.new(encoding: Encoding::BINARY)
	
	if @payload&.bytesize != @length
		raise ProtocolError, "Invalid payload length: #{@length} != #{@payload.bytesize} for #{self}!"
	end
	
	if @mask and @mask.bytesize != 4
		raise ProtocolError, "Invalid mask length!"
	end
	
	if length <= 125
		short_length = length
	elsif length.bit_length <= 16
		short_length = 126
	else
		short_length = 127
	end
	
	buffer << [
		(@finished ? 0b1000_0000 : 0) | (@flags << 4) | @opcode,
		(@mask ? 0b1000_0000 : 0) | short_length,
	].pack('CC')
	
	if short_length == 126
		buffer << [@length].pack('n')
	elsif short_length == 127
		buffer << [@length].pack('Q>')
	end
	
	buffer << @mask if @mask
	
	stream.write(buffer)
	stream.write(@payload)
end