Open Source ASN.1 Compiler
The asn1c is a free, open source compiler of ASN.1 specifications into C source code. It supports a range of ASN.1 syntaxes, including ISO/IEC/ITU ASN.1 1988, '94, '97, 2002 and later amendments. The supported sets of encoding rules are
- BER: ITU-T Rec. X.690 | ISO/IEC 8825-1 (2002) (BER/DER/CER)
- PER: X.691|8825-2 (2002) (PER).
- XER: X.693|8825-3 (2001) (BASIC-XER/CXER).
The compiler was written specifically to address security concerns while providing streaming decoding capabilities.
| Feature | asn1c |
| Restartable/stream decoding1 | YES, for BER and XER families |
| BER (Basic Encoding Rules) | YES |
| DER (a canonical BER subset) | YES |
| CER (another canonical BER subset) | yes, read-only2 |
| BASIC-XER (XML Encoding Rules) | YES |
| CXER ("Canonical" XER) | YES |
| EXTENDED-XER | no |
| PER (Packed Encoding Rules) | YES, UNALIGNED BASIC PER |
| Subtype constraints | YES3 |
| Information Object Classes | basic support |
| C target language | YES |
| C++ target language | YES4 |
| Java target language | no |
| Compiled code portability |
LP64: Linux/alpha, Linux/amd64
ILP32: MacOS X/powerpc (big-endian), Solaris 9/sparc (big-endian); Solaris/x86, FreeBSD/x86, OpenBSD/x86, NetBSD/x86, Linux/x86 (consistency for above platforms is ensured by automated daily testing) ILP32: Windows-CYGWIN, Windows-MSVC++ (minor manual tweaking required for MS platforms) |
| EBCDIC support | provisioned5 |
| License | BSD |
| Cost | $0 |
1) A decoder does not have to have the whole data sequence to start parsing. If it receives less data then required, it will process as much as possible and may be invoked again later, when the next chunk of data becomes available. Question: How to use streaming?
2) Encoding has not been required so far. Please ask for support.
3) The code generator automatically generates constraints checking procedures for PER-visible constraints.
4) C++ compatible C code. No OOP yet.
5) Code has been designed to support EBCDIC charset, but no formal testing has been made yet.