Class: HTTP2::Header::Decompressor

Inherits:
Object
  • Object
show all
Defined in:
lib/http/2/compressor.rb

Overview

Responsible for decoding received headers and maintaining compression context of the opposing peer. Decompressor must be initialized with appropriate starting context based on local role: client or server.

Examples:

server_role = Decompressor.new(:request)
client_role = Decompressor.new(:response)

Instance Method Summary collapse

Constructor Details

#initialize(**options) ⇒ Decompressor

Returns a new instance of Decompressor.

Parameters:

  • options (Hash) —

    decoding options. Only :table_size is effective.



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# File 'lib/http/2/compressor.rb', line 477

def initialize(**options)
  @cc = EncodingContext.new(options)
end

Instance Method Details

#decode(buf) ⇒ Array

Decodes and processes header commands within provided buffer.

Parameters:

Returns:

  • (Array) —

    [[name, value], …]



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# File 'lib/http/2/compressor.rb', line 561

def decode(buf)
  list = []
  list << @cc.process(header(buf)) while !buf.empty?
  list.compact
end

#header(buf) ⇒ Hash

Decodes header command from provided buffer.

Parameters:

Returns:

  • (Hash) —

    command



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# File 'lib/http/2/compressor.rb', line 526

def header(buf)
  peek = buf.readbyte(0)

  header = {}
  header[:type], type = HEADREP.select do |t, desc|
    mask = (peek >> desc[:prefix]) << desc[:prefix]
    mask == desc[:pattern]
  end.first

  header[:type] or raise CompressionError

  header[:name] = integer(buf, type[:prefix])

  case header[:type]
  when :indexed
    header[:name] == 0 and raise CompressionError.new
    header[:name] -= 1
  when :changetablesize
    header[:value] = header[:name]
  else
    if header[:name] == 0
      header[:name] = string(buf)
    else
      header[:name] -= 1
    end
    header[:value] = string(buf)
  end

  header
end

#integer(buf, n) ⇒ Integer

Decodes integer value from provided buffer.

Parameters:

  • buf (String)
  • n (Integer) —

    number of available bits

Returns:

  • (Integer) 


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# File 'lib/http/2/compressor.rb', line 492

def integer(buf, n)
  limit = 2**n - 1
  i = !n.zero? ? (buf.getbyte & limit) : 0

  m = 0
  while byte = buf.getbyte do
    i += ((byte & 127) << m)
    m += 7

    break if (byte & 128).zero?
  end if (i == limit)

  i
end

#set_table_size(size) ⇒ Object

Set header table size in EncodingContext

Parameters:

  • size (Integer) —

    new header table size



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# File 'lib/http/2/compressor.rb', line 483

def set_table_size(size)
  @cc.set_table_size(size)
end

#string(buf) ⇒ String

Decodes string value from provided buffer.

Parameters:

  • buf (String)

Returns:

  • (String) —

    UTF-8 encoded string

Raises:

  • (CompressionError) —

    when input is malformed



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# File 'lib/http/2/compressor.rb', line 512

def string(buf)
  huffman = (buf.readbyte(0) & 0x80) == 0x80
  len = integer(buf, 7)
  str = buf.read(len)
  str.bytesize == len or raise CompressionError.new("string too short")
  huffman and str = Huffman.new.decode(Buffer.new(str))
  str = str.force_encoding('utf-8')
  str
end