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asn1rs - ASN.1 Compiler for Rust

This crate generates Rust Code and optionally compatible Protobuf and SQL schema files from ASN.1 definitions. Integration with serde is supported.

The crate can be used as standalone CLI binary or used as library through its API (for example inside your build.rs script).

Supported Features

• ✔️ yes: according to specification
• ✔️ yes¹: different representation
• ✔️ yes²: as close as possible to the original specification (sometimes yes, sometimes yes¹)
• 🔶 not serialized: values are not serialized or deserialized in this case, might break compatibility
• ⚠️ ignored️: constraint is ignored, this most likely breaks compatibility
• 🆗 ignored: constraint is ignored but it does not break compatibility
• ❌ ub: undefined behavior - whatever seems reasonable to prevent compiler errors and somehow transmit the value
• 🟥 error: fails to compile / translate

Supported standards

• 📜️ ETSI TS 102 894-2 (PDF) / 🧰 ITS-Container (GIT):
  itu-t(0) identified-organization(4) etsi(0) itsDomain(5) wg1(1) ts(102894) cdd(2) version(2)
• 📜️ ETSI EN 302 637-2 (PDF) / 🧰 CAM-PDU-Description (GIT):
  itu-t(0) identified-organization(4) etsi(0) itsDomain(5) wg1(1) en(302637) cam(2) version(2)
• 📜️ ETSI EN 302 637-3 (PDF) / 🧰 DENM-PDU-Descriptions (GIT):
  itu-t(0) identified-organization(4) etsi(0) itsDomain(5) wg1(1) en(302637) denm(1) version(2)

CLI usage

It is always helpful to check asn1rs --help in advance. The basic usage can be seen blow:

asn1rs -t rust directory/for/rust/files some.asn1 messages.asn1

asn1rs -t proto directory/for/protobuf/files some.asn1 messages.asn1

Example: build.rs

The following example generates Rust and Protobuf files for all .asn1-files in the asn/ directory of a workspace. While the generated Rust code is written to the src/ directory, the Protobuf files are written to proto/. Additionally, in this example each generated Rust-Type also receives Serialize and Deserialize derive directives (#[derive(Serialize, Deserialize)]) for serde integration.

Sample build.rs file:

use asn1rs::converter::Converter;
use asn1rs::gen::rust::RustCodeGenerator;

pub fn main() {
    let mut converter = Converter::default();

    // collecting all relevant .asn1 files
    std::fs::read_dir("../protocol/asn")
        .into_iter()
        .flat_map(|read_dir| {
            read_dir
                .into_iter()
                .flat_map(|dir_entry| dir_entry.into_iter())
                .flat_map(|entry| {
                    entry
                        .path()
                        .as_os_str()
                        .to_os_string()
                        .into_string()
                        .into_iter()
                })
                .filter(|entry| entry.ends_with(".asn1"))
        })
        .for_each(|path| {
            println!("cargo:rerun-if-changed={}", path);
            if let Err(e) = converter.load_file(&path) {
                panic!("Loading of .asn1 file failed {}: {:?}", path, e);
            }
        });

    // writing the .rs files into src with serde_derive support
    // feature flags decide whether additional code for protobuf is generated
    if let Err(e) = converter.to_rust("src/", |generator: &mut RustCodeGenerator| {
        generator.add_global_derive("Serialize"); // Adds serde_derive support: #[derive(Serialize)]
        generator.add_global_derive("Deserialize"); // Adds serde_derive support: #[derive(Deserialize)]
    }) {
        panic!("Conversion to rust failed: {:?}", e);
    }

    // OPTIONAL: writing the .proto representation to ../protocol/proto
    if let Err(e) = converter.to_protobuf("../protocol/proto/") {
        panic!("Conversion to proto failed: {:?}", e);
    }
}

Example: Inlining ASN.1 with procedural macros

Minimal example by inlining the ASN.1 definition. For more examples see tests/.

use asn1rs::prelude::*;

asn_to_rust!(
    r"BasicInteger DEFINITIONS AUTOMATIC TAGS ::=
    BEGIN
    
    RangedMax ::= Integer (0..MAX)
    
    NotRanged ::= Integer
    
    END"
);

#[test]
fn test_write_read() {
    // inner INTEGER identified as u64
    let value = NotRanged(123_u64);

    let mut writer = UperWriter::default();
    writer.write(&value).expect("Failed to serialize");

    let mut reader = writer.into_reader();
    let value2 = reader.read::<NotRanged>().expect("Failed to deserialize");
    
    assert_eq!(value, value2);
}

#[test]
fn test_constraint_eq() {
    // these types should normally not be accessed, but in this exampled they show
    // the way the ASN.1 constraints are encoded with the Rust type system.
    use asn1rs::syn::numbers::Constraint;
    assert_eq!(
        ___asn1rs_RangedMaxField0Constraint::MIN,
        ___asn1rs_NotRangedField0Constraint::MIN,
    );
    assert_eq!(
        ___asn1rs_RangedMaxField0Constraint::MAX,
        ___asn1rs_NotRangedField0Constraint::MAX,
    );
}

Example: ASN.1-Definition converted to Rust and Protobuf

Minimal example showcasing what is being generated from an ASN.1 definition:

MyMessages DEFINITIONS AUTOMATIC TAGS ::=
BEGIN

Header ::= SEQUENCE {
    timestamp    INTEGER (0..1209600000)
}

END

The generated Rust file:

use asn1rs::prelude::*;

#[asn(sequence)]
#[derive(Default, Debug, Clone, PartialEq, Hash)]
pub struct Header {
    #[asn(integer(0..1209600000))] pub timestamp: u32,
}

The generated protobuf file (optional):

syntax = 'proto3';
package my.messages;

message Header {
    uint32 timestamp = 1;
}

Example: Raw uPER usage

The module asn1rs::io exposes (de-)serializers and helpers for direct usage without ASN.1 definition:

use asn1rs::prelude::*;
use asn1rs::io::per::unaligned::buffer::BitBuffer;

let mut buffer = BitBuffer::default();
buffer.write_bit(true).unwrap();
buffer.write_utf8_string("My UTF8 Text").unwrap();

send_to_another_host(buffer.into::<Vec<u8>>()):

Example: Raw Protobuf usage

The module asn1rs::io::protobuf exposes (de-)serializers for protobuf usage:

use asn1rs::io::protobuf::*;

let mut buffer = Vec::default();
buffer.write_varint(1337).unwrap();
buffer.write_string("Still UTF8 Text").unwrap();

send_to_another_host(buffer):

Extending Rust Codegen

use asn1rs::model::model::gen::rust::RustCodeGenerator;
use asn1rs::model::model::gen::rust::GeneratorSupplement;

impl GeneratorSupplement<Rust> for MyRustCodeGeneratorExtension {
    // .. implement the trait
}

fn main() {
    let model: Model<Rust> = ... ;
    let (_file_name, file_content) = RustCodeGenerator::from(model)
        .to_string_with_generators(&[&MyRustCodeGeneratorExtension])
        .into_iter()
        .next()
        .unwrap();
}

Finding deserialization error origins

For a more detailed report on deserialization errors, enable the descriptive-deserialize-errors feature. With this feature flag more details will be memorized while deserializing your data (see ScopeDescription) - thus causing a performance penalty - but it will list intermediate results with the error origin and the current location in the type hierarchy when displaying the error ( println!("{e}"));

TODO

Things to do at some point in time (PRs are welcome)

• generate a proper rust module hierarchy from the modules' object-identifier
• support #![no_std]
• refactor / clean-up (rust) code-generators (most will be removed in v0.3.0)
• support more encoding formats of ASN.1 (help is welcome!)

License

Origin