ASN.1 Compiler for C(Python)¶

Important

This project was started by vlm and then updated for recent bug fixes by mouse07410. Any updates from these projects will be merged into this one.

About¶

ASN.1 to C compiler takes the ASN.1 module files (example) and generates the C++ compatible C source code. That code can be used to serialize the native C structures into compact and unambiguous BER/OER/PER/XER/JER-based data files, and deserialize the files back.

Note

This version of the ASN.1 compiler includes functionality to generate Python bindings automatically - no coding involved.

Various ASN.1 based formats are widely used in the industry, such as to encode the X.509 certificates employed in the HTTPS handshake, to exchange control data between mobile phones and cellular networks, to perform car-to-car communication in intelligent transportation networks.

The ASN.1 family of standards is large and complex, and no open source compiler supports it in its entirety. The asn1c is arguably the most evolved open source ASN.1 compiler. Additionally, using this project, the asn1c compiler is now capable of generating Python bindings.

A simple Example¶

Lets consider the following ASN.1 definition using basic types only:

ExampleModule DEFINITIONS AUTOMATIC TAGS ::= BEGIN

   ExampleSequence ::= SEQUENCE {
      foo      INTEGER,
      bar      REAL,
      baz      BOOLEAN
   }

END

After compiling the extension module e.g. into (example_mod._example_mod), the type above can be used as a generic Python class:

from example_mod._example_mod import ExampleSequence

seq = ExampleSequence() # kw-only, all values are optional
assert seq.foo == 0     # all elements will be initialiazed with zero
seq.foo = 100           # assignment works just like that
assert seq.foo == 100

# to encode or decode using a specific rules, just use the codec name
# as a prefix: (e.g. BER -> obj.ber_encode, ExampleSequence.ber_decode)
data = seq.ber_encode()
parsed = ExampleSequence.ber_decode(data)
assert parsed.foo == seq.foo

Supported Types¶

Basic Types: NULL, INTEGER (named), BOOLEAN, BIT STRING (named), OCTET STRING, OBJECT IDENTIFIER,, RELATIVE-OID, REAL, ENUMERATED, UTF8String and variants, CHARACTER STRING, ANY, time types, EMBEDDED PDV and open types.

Note

UTCTIME and GeneralizedTime are both implemented as strings.

Constructed Types: SEQUENCE, CHOICE, SET, SEQUENCE OF, SET OF (anonymous types are supported too, e.g. SET OF SET)

Basics

Reference: