Module: Requests::HPACK::Huffman

Defined in:
lib/requests/hpack.rb

Constant Summary collapse

CODES = 
[
  [0x1ff8, 13],[0x7fffd8, 23],[0xfffffe2, 28],[0xfffffe3, 28],[0xfffffe4, 28],[0xfffffe5, 28],
  [0xfffffe6, 28],[0xfffffe7, 28],[0xfffffe8, 28],[0xffffea, 24],[0x3ffffffc, 30],[0xfffffe9, 28],
  [0xfffffea, 28],[0x3ffffffd, 30],[0xfffffeb, 28],[0xfffffec, 28],[0xfffffed, 28],[0xfffffee, 28],
  [0xfffffef, 28],[0xffffff0, 28],[0xffffff1, 28],[0xffffff2, 28],[0x3ffffffe, 30],[0xffffff3, 28],
  [0xffffff4, 28],[0xffffff5, 28],[0xffffff6, 28],[0xffffff7, 28],[0xffffff8, 28],[0xffffff9, 28],
  [0xffffffa, 28],[0xffffffb, 28],[0x14, 6],[0x3f8, 10],[0x3f9, 10],[0xffa, 12],
  [0x1ff9, 13],[0x15, 6],[0xf8, 8],[0x7fa, 11],[0x3fa, 10],[0x3fb, 10],
  [0xf9, 8],[0x7fb, 11],[0xfa, 8],[0x16, 6],[0x17, 6],[0x18, 6],
  [0x0, 5],[0x1, 5],[0x2, 5],[0x19, 6],[0x1a, 6],[0x1b, 6],
  [0x1c, 6],[0x1d, 6],[0x1e, 6],[0x1f, 6],[0x5c, 7],[0xfb, 8],
  [0x7ffc, 15],[0x20, 6],[0xffb, 12],[0x3fc, 10],[0x1ffa, 13],[0x21, 6],
  [0x5d, 7],[0x5e, 7],[0x5f, 7],[0x60, 7],[0x61, 7],[0x62, 7],
  [0x63, 7],[0x64, 7],[0x65, 7],[0x66, 7],[0x67, 7],[0x68, 7],
  [0x69, 7],[0x6a, 7],[0x6b, 7],[0x6c, 7],[0x6d, 7],[0x6e, 7],
  [0x6f, 7],[0x70, 7],[0x71, 7],[0x72, 7],[0xfc, 8],[0x73, 7],
  [0xfd, 8],[0x1ffb, 13],[0x7fff0, 19],[0x1ffc, 13],[0x3ffc, 14],[0x22, 6],
  [0x7ffd, 15],[0x3, 5],[0x23, 6],[0x4, 5],[0x24, 6],[0x5, 5],
  [0x25, 6],[0x26, 6],[0x27, 6],[0x6, 5],[0x74, 7],[0x75, 7],
  [0x28, 6],[0x29, 6],[0x2a, 6],[0x7, 5],[0x2b, 6],[0x76, 7],
  [0x2c, 6],[0x8, 5],[0x9, 5],[0x2d, 6],[0x77, 7],[0x78, 7],
  [0x79, 7],[0x7a, 7],[0x7b, 7],[0x7ffe, 15],[0x7fc, 11],[0x3ffd, 14],
  [0x1ffd, 13],[0xffffffc, 28],[0xfffe6, 20],[0x3fffd2, 22],[0xfffe7, 20],[0xfffe8, 20],
  [0x3fffd3, 22],[0x3fffd4, 22],[0x3fffd5, 22],[0x7fffd9, 23],[0x3fffd6, 22],[0x7fffda, 23],
  [0x7fffdb, 23],[0x7fffdc, 23],[0x7fffdd, 23],[0x7fffde, 23],[0xffffeb, 24],[0x7fffdf, 23],
  [0xffffec, 24],[0xffffed, 24],[0x3fffd7, 22],[0x7fffe0, 23],[0xffffee, 24],[0x7fffe1, 23],
  [0x7fffe2, 23],[0x7fffe3, 23],[0x7fffe4, 23],[0x1fffdc, 21],[0x3fffd8, 22],[0x7fffe5, 23],
  [0x3fffd9, 22],[0x7fffe6, 23],[0x7fffe7, 23],[0xffffef, 24],[0x3fffda, 22],[0x1fffdd, 21],
  [0xfffe9, 20],[0x3fffdb, 22],[0x3fffdc, 22],[0x7fffe8, 23],[0x7fffe9, 23],[0x1fffde, 21],
  [0x7fffea, 23],[0x3fffdd, 22],[0x3fffde, 22],[0xfffff0, 24],[0x1fffdf, 21],[0x3fffdf, 22],
  [0x7fffeb, 23],[0x7fffec, 23],[0x1fffe0, 21],[0x1fffe1, 21],[0x3fffe0, 22],[0x1fffe2, 21],
  [0x7fffed, 23],[0x3fffe1, 22],[0x7fffee, 23],[0x7fffef, 23],[0xfffea, 20],[0x3fffe2, 22],
  [0x3fffe3, 22],[0x3fffe4, 22],[0x7ffff0, 23],[0x3fffe5, 22],[0x3fffe6, 22],[0x7ffff1, 23],
  [0x3ffffe0, 26],[0x3ffffe1, 26],[0xfffeb, 20],[0x7fff1, 19],[0x3fffe7, 22],[0x7ffff2, 23],
  [0x3fffe8, 22],[0x1ffffec, 25],[0x3ffffe2, 26],[0x3ffffe3, 26],[0x3ffffe4, 26],[0x7ffffde, 27],
  [0x7ffffdf, 27],[0x3ffffe5, 26],[0xfffff1, 24],[0x1ffffed, 25],[0x7fff2, 19],[0x1fffe3, 21],
  [0x3ffffe6, 26],[0x7ffffe0, 27],[0x7ffffe1, 27],[0x3ffffe7, 26],[0x7ffffe2, 27],[0xfffff2, 24],
  [0x1fffe4, 21],[0x1fffe5, 21],[0x3ffffe8, 26],[0x3ffffe9, 26],[0xffffffd, 28],[0x7ffffe3, 27],
  [0x7ffffe4, 27],[0x7ffffe5, 27],[0xfffec, 20],[0xfffff3, 24],[0xfffed, 20],[0x1fffe6, 21],
  [0x3fffe9, 22],[0x1fffe7, 21],[0x1fffe8, 21],[0x7ffff3, 23],[0x3fffea, 22],[0x3fffeb, 22],
  [0x1ffffee, 25],[0x1ffffef, 25],[0xfffff4, 24],[0xfffff5, 24],[0x3ffffea, 26],[0x7ffff4, 23],
  [0x3ffffeb, 26],[0x7ffffe6, 27],[0x3ffffec, 26],[0x3ffffed, 26],[0x7ffffe7, 27],[0x7ffffe8, 27],
  [0x7ffffe9, 27],[0x7ffffea, 27],[0x7ffffeb, 27],[0xffffffe, 28],[0x7ffffec, 27],[0x7ffffed, 27],
  [0x7ffffee, 27],[0x7ffffef, 27],[0x7fffff0, 27],[0x3ffffee, 26],[0x3fffffff, 30]
].freeze
EOS = 
256
ENCODE_TABLE = 
CODES.map { |c, l| [c].pack('N').unpack1('B*')[-l..-1] }.freeze
DECODE_TREE = 
build_tree

Class Method Summary collapse

Class Method Details

.build_tree ⇒ Object 



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# File 'lib/requests/hpack.rb', line 72

def self.build_tree
  root = {}
  CODES.each_with_index do |(code, len), sym|
    node = root
    (len - 1).downto(0) do |i|
      bit = (code >> i) & 1
      node = (node[bit] ||= {})
    end
    node[:sym] = sym
  end
  root
end

.decode(bytes) ⇒ Object 



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# File 'lib/requests/hpack.rb', line 92

def self.decode(bytes)
  out = String.new(encoding: Encoding::BINARY)
  node = DECODE_TREE
  bitcount = bytes.bytesize * 8
  pos = 0
  bytes.each_byte do |byte|
    7.downto(0) do |i|
      pos += 1
      bit = (byte >> i) & 1
      nxt = node[bit]
      unless nxt
        raise Requests::ContentDecodingError, 'invalid huffman padding' if pos > bitcount - 8 || pos < bitcount
        return out
      end
      node = nxt
      if node.key?(:sym)
        sym = node[:sym]
        raise Requests::ContentDecodingError, 'unexpected huffman EOS' if sym == EOS
        out << sym.chr(Encoding::BINARY)
        node = DECODE_TREE
      end
    end
  end
  out
end

.encode(str) ⇒ Object 



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# File 'lib/requests/hpack.rb', line 85

def self.encode(str)
  bits = String.new
  str.each_byte { |b| bits << ENCODE_TABLE[b] }
  pad = (8 - bits.size % 8) % 8
  bits << ('1' * pad) if pad > 0
  [bits].pack('B*')
end