asn1vnparser 0.2.0

Parses ASN.1 value notation into a Python object or JSON without requiring its ASN.1 schema.

asn1vnparser

Parses ASN.1 value notation into a Python object or JSON without requiring its ASN.1 schema.

• Free software: MIT license

• Documentation: https://asn1vnparser.readthedocs.io.

Features

• Parsing ASN.1 value notation into a Python object, or a JSON string

• No ASN.1 Schema Required

Limitations

• Since Knowledge of schema is not used, misdetection of ASN.1 types can occur; see Type Translations section.

• Some ASN.1 types and grammars are not supported; see grammar.py.

Type Translations

asn1vnparser performs the following type translations:

ASN.1 Type	Python Type	JSON Type	Example (ASN.1 -> Python)
NULL	None	null	NULL -> None
BOOLEAN	bool	True/False	TRUE -> True
INTEGER	int	number (int)	3 -> 3
REAL	float	number (real)	0.1 -> 0.1
BIT STRING (^1)	bitarray.bitarray	string (e.g. “010101”)	‘010101’B -> bitarray.bitarray(‘010101’)
OCTET STRING (^1)	bytes	string (e.g. “0123ab”)	‘0123AB’H -> b’x01x23xab’
cstring (PrintableString, etc.)	str	string	“foobar” -> ‘foobar’
ENUMERATED	str	string	any-identifier -> ‘any-identifier’
CHOICE	Dict[str, Any]	{“string”: (any JSON object)}	alt1 : 123 -> {‘alt1’: 123}
Open Type (e.g. type field)	Dict[str, Any]	{“String”: (any JSON object)}	Type1 : 123 -> {‘Type1’: 123}
empty SEQUENCE or SEQUENCE OF	{} (empty dict)	{} (empty object)	{} -> {}, [] -> {}
SEQUENCE	dict	object	{f1 val, f2 1} -> {‘f1’: ‘val’, ‘f2’: 1}
SEQUENCE OF	list	array	[1, 2, 3] -> [1, 2, 3]
OBJECT IDENTIFIER	List[int]	array of number (int)	{1 2 3} -> [1, 2, 3]

(^1) CONTAINING (some_value) is interpreted as simply (some_value), e.g.:

{
    field1 123,
    field2 CONTAINING {
        field2-1 TRUE,
        field2-2 FALSE
    }
}

is parsed into following Python object:

{
    "field1": 123,
    "field2": {
        "field2-1": True,
        "field2-2": False
    }
}

Credits

This package was created with Cookiecutter and the audreyr/cookiecutter-pypackage project template.

History

0.2.0 (2019-10-02)

New Features

• Partial parsing of a value or a value assignment (parse_all option)

>>> parse_asn1_value(
...     "alt1: enum1\n---this is remaining string---",
...     as_json=True,
...     parse_all=False)  # as_json
('{"alt1": "enum1"}', '\n---this is remaining string---')

• Parsing multiple value assignments

>>> parse_asn1_value_assignments(
...     'value1 INTEGER ::= 1\nvalue2 Type2 ::= the-value')
[
    {'value_name': 'value1', 'type_name': 'INTEGER', 'value': 1},
    {'value_name': 'value2', 'type_name': 'Type2', 'value': 'the-value'}
]

Bug Fixes

• CLI no longer crashes when given --json option.

0.1.0 (2019-09-29)

• First release on PyPI.