tls_client_hello: Ruby parsing library

KS implementation details

License: MIT

References

This page hosts a formal specification of tls_client_hello using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.

The Ruby runtime library can be installed from RubyGems:

gem install kaitai-struct

Code

Parse a local file and get structure in memory:

data = TlsClientHello.from_file("path/to/local/file.tls_client_hello")

Or parse structure from a string of bytes:

bytes = "\x00\x01\x02..."
data = TlsClientHello.new(Kaitai::Struct::Stream.new(bytes))

After that, one can get various attributes from the structure by invoking getter methods like:

data.version # => get version

Ruby source code to parse tls_client_hello

tls_client_hello.rb

# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

require 'kaitai/struct/struct'

unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
  raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end

class TlsClientHello < Kaitai::Struct::Struct
  def initialize(_io, _parent = nil, _root = self)
    super(_io, _parent, _root)
    _read
  end

  def _read
    @version = Version.new(@_io, self, @_root)
    @random = Random.new(@_io, self, @_root)
    @session_id = SessionId.new(@_io, self, @_root)
    @cipher_suites = CipherSuites.new(@_io, self, @_root)
    @compression_methods = CompressionMethods.new(@_io, self, @_root)
    if _io.eof? == false
      @extensions = Extensions.new(@_io, self, @_root)
    end
    self
  end
  class ServerName < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @name_type = @_io.read_u1
      @length = @_io.read_u2be
      @host_name = @_io.read_bytes(length)
      self
    end
    attr_reader :name_type
    attr_reader :length
    attr_reader :host_name
  end
  class Random < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @gmt_unix_time = @_io.read_u4be
      @random = @_io.read_bytes(28)
      self
    end
    attr_reader :gmt_unix_time
    attr_reader :random
  end
  class SessionId < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @len = @_io.read_u1
      @sid = @_io.read_bytes(len)
      self
    end
    attr_reader :len
    attr_reader :sid
  end
  class Sni < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @list_length = @_io.read_u2be
      @server_names = []
      i = 0
      while not @_io.eof?
        @server_names << ServerName.new(@_io, self, @_root)
        i += 1
      end
      self
    end
    attr_reader :list_length
    attr_reader :server_names
  end
  class CipherSuites < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @len = @_io.read_u2be
      @cipher_suites = Array.new((len / 2))
      ((len / 2)).times { |i|
        @cipher_suites[i] = @_io.read_u2be
      }
      self
    end
    attr_reader :len
    attr_reader :cipher_suites
  end
  class CompressionMethods < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @len = @_io.read_u1
      @compression_methods = @_io.read_bytes(len)
      self
    end
    attr_reader :len
    attr_reader :compression_methods
  end
  class Alpn < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @ext_len = @_io.read_u2be
      @alpn_protocols = []
      i = 0
      while not @_io.eof?
        @alpn_protocols << Protocol.new(@_io, self, @_root)
        i += 1
      end
      self
    end
    attr_reader :ext_len
    attr_reader :alpn_protocols
  end
  class Extensions < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @len = @_io.read_u2be
      @extensions = []
      i = 0
      while not @_io.eof?
        @extensions << Extension.new(@_io, self, @_root)
        i += 1
      end
      self
    end
    attr_reader :len
    attr_reader :extensions
  end
  class Version < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @major = @_io.read_u1
      @minor = @_io.read_u1
      self
    end
    attr_reader :major
    attr_reader :minor
  end
  class Protocol < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @strlen = @_io.read_u1
      @name = @_io.read_bytes(strlen)
      self
    end
    attr_reader :strlen
    attr_reader :name
  end
  class Extension < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @type = @_io.read_u2be
      @len = @_io.read_u2be
      case type
      when 0
        @_raw_body = @_io.read_bytes(len)
        _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
        @body = Sni.new(_io__raw_body, self, @_root)
      when 16
        @_raw_body = @_io.read_bytes(len)
        _io__raw_body = Kaitai::Struct::Stream.new(@_raw_body)
        @body = Alpn.new(_io__raw_body, self, @_root)
      else
        @body = @_io.read_bytes(len)
      end
      self
    end
    attr_reader :type
    attr_reader :len
    attr_reader :body
    attr_reader :_raw_body
  end
  attr_reader :version
  attr_reader :random
  attr_reader :session_id
  attr_reader :cipher_suites
  attr_reader :compression_methods
  attr_reader :extensions
end