Class: RASN1::Types::Choice

Inherits:
Base
  • Object
show all
Defined in:
lib/rasn1/types/choice.rb

Overview

A ASN.1 CHOICE is a choice between different types.

Create a CHOICE

A CHOICE is defined this way:

choice = Choice.new
choice.value = [Integer.new(implicit: 0, class: :context),
                Integer.new(implicit: 1, class: :context),
                OctetString.new(implicit: 2, class: :context)]

The chosen type may be set this way:

choice.chosen = 0   # choose :int1

The chosen value may be set these ways:

choise.value[choice.chosen].value = 1
choise.set_chosen_value 1

The chosen value may be got these ways:

choise.value[choice.chosen].value # => 1
choice.chosen_value               # => 1

Encode a CHOICE

#to_der only encodes the chosen value:

choise.to_der   # => "\x80\x01\x01"

Parse a CHOICE

Parsing a CHOICE set #chosen and set value to chosen type. If parsed string does not contain a type from CHOICE, a ASN1Error is raised.

str = "\x04\x03abc"
choice.parse! str
choice.chosen        # => 2
choice.chosen_value  # => "abc"

Author:

  • Sylvain Daubert

Constant Summary

Constants inherited from Base

Base::CLASSES, Base::INDEFINITE_LENGTH, Base::MAX_TAG

Instance Attribute Summary collapse

Attributes inherited from Base

#asn1_class, #default, #name, #value

Instance Method Summary collapse

Methods inherited from Base

#==, #constructed?, #explicit?, #implicit?, #initialize, #initialize_copy, #optional?, parse, #primitive?, #tag, #tagged?, type, #type, #value_size

Constructor Details

This class inherits a constructor from RASN1::Types::Base

Instance Attribute Details

#chosen ⇒ Integer

Chosen type

Returns:

  • (Integer) —

    index of type in choice value



37
38
39
 
# File 'lib/rasn1/types/choice.rb', line 37

def chosen
  @chosen
end

Instance Method Details

#chosen_value ⇒ Object

Note:

#chosen MUST be set before calling this method

Get chosen value

Returns:

  • (Object) —

    value

Raises:



53
54
55
56
57
58
59
60
61
 
# File 'lib/rasn1/types/choice.rb', line 53

def chosen_value
  check_chosen
  case @value[@chosen]
  when Base
    @value[@chosen].value
  when Model
    @value[@chosen]
  end
end

#inspect(level = 0) ⇒ Object 



93
94
95
96
97
98
99
100
101
102
 
# File 'lib/rasn1/types/choice.rb', line 93

def inspect(level=0)
  str = ''
  str << '  ' * level if level > 0
  str << "#{name} #{type}: "
  if @chosen.nil?
    str << 'not chosen!'
  else
    str << @value[@chosen].inspect(level)
  end
end

#parse!(der, ber: false) ⇒ Integer

Parse a DER string. This method updates object by setting #chosen and chosen value.

Parameters:

  • der (String) —

    DER string

  • ber (Boolean) (defaults to: false) —

    if true, accept BER encoding

Returns:

  • (Integer) —

    total number of parsed bytes

Raises:



77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
 
# File 'lib/rasn1/types/choice.rb', line 77

def parse!(der, ber: false)
  parsed = false
  @value.each_with_index do |element, i|
    begin
      @chosen = i
      nb_bytes = element.parse!(der)
      parsed = true
      return nb_bytes
    rescue ASN1Error
      @chosen = nil
      next
    end
  end
  raise ASN1Error, "CHOICE #@name: no type matching #{der.inspect}" unless parsed
end

#set_chosen_value(value) ⇒ Object

Note:

#chosen MUST be set before calling this method

Set chosen value.

Parameters:

  • value (Object)

Returns:

  • (Object) —

    value

Raises:



44
45
46
47
 
# File 'lib/rasn1/types/choice.rb', line 44

def set_chosen_value(value)
  check_chosen
  @value[@chosen].value = value
end

#to_der ⇒ String

Note:

#chosen MUST be set before calling this method

Returns DER-formated string.

Returns:

  • (String) —

    DER-formated string

Raises:



66
67
68
69
 
# File 'lib/rasn1/types/choice.rb', line 66

def to_der
  check_chosen
  @value[@chosen].to_der
end