gistfile1.rb

# curl 'http://ws.example.com/ws' \
#   -H 'Pragma: no-cache' \
#   -H 'Origin: http://ws.example.com/' \
#   -H 'Accept-Language: ja-JP,ja;q=0.9,en;q=0.8' \
#   -H 'Sec-WebSocket-Key: BASE64_NONCE' \
#   -H 'Upgrade: websocket' \
#   -H 'Sec-WebSocket-Version: 13' \
#   --compressed \
#   --output ~/out
#
# Notice: 'Sec-Websocket-Accept' response header will not be verified.

WebSocketOpcode = {
  0  => :Continuation,
  1  => :Text,
  2  => :Binary,
  8  => :ConnectionClose,
  9  => :Ping,
  10 => :Pong,
}

WebSocketPacket = Struct.new(:fin, :rsv1, :rsv2, :rsv3, :opcode, :mask, :payload_length, :masking_key, :payload) do
  class << self
    def read(io)
      first_octet, second_octet = io.read(2).bytes

      fin    = (first_octet & 0b1000_0000) != 0
      rsv1   = (first_octet & 0b0100_0000) != 0
      rsv2   = (first_octet & 0b0010_0000) != 0
      rsv3   = (first_octet & 0b0001_0000) != 0
      opcode = (first_octet & 0b0000_1111)

      mask   = (second_octet & 0b1000_0000) != 0

      payload_length = (second_octet & 0b0111_1111)
      case payload_length
      when 126 
        payload_length = bytes_to_int(io.read(2).bytes)
      when 127
        payload_length = bytes_to_int(io.read(8).bytes)
      end

      masking_key = nil
      if mask
        masking_key = bytes_to_int(io.read(4).bytes)
      end

      payload = io.read(payload_length)

      self.new(fin, rsv1, rsv2, rsv3, opcode, mask, payload_length, masking_key, payload)
    end

    private
    # Network byte order
    def bytes_to_int(bytes)
      bytes.reduce(0) {|accum, b| (accum << 8) + b }
    end
  end
end

#file = ARGV[0]
file = File.expand_path("~/out")

File.open(file, "r") do |input|
  until input.eof?
    pkt = WebSocketPacket.read(input)
    File.open("~/outws.mp4", "a") do |out|
      out.write(pkt.payload)
    end
  end
end