class ASN1::BER

• ASN1::BER
• BinData
• Reference
• Object

Overview

A single ASN.1 Basic Encoding Rules (BER) TLV element: an identifier (tag), a length and a payload. Used to build and parse SNMP, LDAP, X.509 and similar protocols.

require "bindata/asn1"

ber = ASN1::BER.new
ber.set_integer(42)
io.write_bytes(ber)

ber = io.read_bytes(ASN1::BER)
ber.get_integer # => 42

Typed payload accessors live in data_types.cr (#get_integer/#set_integer, #get_object_id/#set_object_id, #get_string, #get_boolean, ...). A constructed element can be split into / built from sub-elements with #children / #children=.

Defined in:

Constant Summary

AFTER_DESERIALIZE = [] of Nil

BEFORE_SERIALIZE = [] of Nil

ENDIAN = ["big"]

KLASS_NAME = [ASN1::BER]

PARTS = [{type: "basic", name: identifier, cls: ASN1::BER::Identifier, onlyif: nil, verify: nil, value: nil}, {type: "basic", name: length, cls: ASN1::BER::Length, onlyif: nil, verify: nil, value: nil}] of Nil

REMAINING = [] of Nil

Class Method Summary

• .bit_fields

Macro Summary

• asn1_ber(name, onlyif = nil, verify = nil, value = nil)
• ber(name, onlyif = nil, verify = nil, value = nil)

Instance Method Summary

• #__format__ : IO::ByteFormat

  A group captures the endianness at its declaration point, so declaring endian after one would silently leave it system-endian.

• #children

  Parses the payload as a sequence of nested BER elements.

• #children=(parts)

  Encodes parts into the payload and marks this element constructed.

• #constructed
• #constructed=(custom : Bool)
• #extended
• #extended=(parts : Array(ExtendedIdentifier))
• #extended?
• #get_bitstring

  Reads the payload as a BIT STRING (only the zero-unused-bits form is supported).

• #get_boolean

  Reads the payload as a BOOLEAN.

• #get_bytes : Slice(UInt8)

  Returns the raw bytes

• #get_hexstring(universal = true, tag = UniversalTags::OctetString)

  Gets a hex representation of the bytes

• #get_integer(check_tags = {UniversalTags::Integer, UniversalTags::Enumerated}, check_class = TagClass::Universal) : Int64

  Reads the payload as a two's-complement signed INTEGER (or ENUMERATED).

• #get_integer_bytes : Bytes

  Returns the INTEGER payload as raw bytes, with a leading zero/sign pad removed.

• #get_object_id

  Returns the object ID in string format.

• #get_string

  Returns a UTF8 string

• #identifier : Identifier

  Components of a BER object

• #identifier=(identifier : Identifier)

  Components of a BER object

• #inspect(io : IO) : Nil

  Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.

• #length : Length
• #length=(length : Length)
• #max_content_length : Int32

  Maximum number of payload bytes this object (and its children) may allocate or read.

• #max_content_length=(max_content_length : Int32)

  Maximum number of payload bytes this object (and its children) may allocate or read.

• #payload : Bytes
• #payload=(payload : Bytes)
• #read(io : IO) : IO

  Reads the fields of this instance from io, in declaration order, and returns io.

• #sequence?

  Whether this is a constructed universal Sequence or Set, i.e.

• #set_boolean(value)

  Sets a BOOLEAN payload.

• #set_bytes(data, tag = UniversalTags::OctetString, tag_class = TagClass::Universal)

  Sets the raw payload bytes and the given tag.

• #set_hexstring(string, tag = UniversalTags::OctetString, tag_class = TagClass::Universal)

  Sets bytes from a hexstring

• #set_integer(value, tag = UniversalTags::Integer, tag_class = TagClass::Universal)

  Encodes value as a minimal two's-complement INTEGER payload.

• #set_object_id(oid)

  Sets a string representing an object ID.

• #set_string(string, tag = UniversalTags::UTF8String, tag_class = TagClass::Universal)

  Sets a UTF8 string

• #size

  The decoded payload length in bytes.

• #tag

  The universal tag as a UniversalTags enum.

• #tag_class
• #tag_class=(tag : TagClass)
• #tag_number
• #tag_number=(tag_type : Int | UniversalTags)
• #write(io : IO)

  Writes the fields of this instance to io in declaration order.

Class Method Detail

Macro Detail

Instance Method Detail

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).inspect # => #<Person:0x10fd31f20 @name="John", @age=32>

ber = ASN1::BER.new
ber.max_content_length = 64 * 1024
ber.read(io)

ber = ASN1::BER.new
ber.max_content_length = 64 * 1024
ber.read(io)