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

*The legacy UPER Reader/Writer is deprecated and will be removed in version 0.3.0

TLDR

• The new (v0.2.0) UPER Reader/Writer supports all listed features
• Protobuf, sync&async PSQL ignore most constraints
• The legacy UPER Reader/Writer does not support all features (pre v0.2.0)

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

asn1rs -t sql directory/for/sql/schema/files some.asn1 messages.asn1

Example: build.rs

The following example generates Rust, Protobuf and SQL 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/ and the SQL files are written to sql/ . 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;
use asn1rs::gen::sql::SqlDefGenerator;

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 and (async) psql 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);
    }

    // OPTIONAL: writing the .sql schema files to ../protocol/sql
    if let Err(e) = converter.to_sql_with(
        "../protocol/sql/",
        SqlDefGenerator::default() // optional parameter, alternatively see Converter::to_sql(&self, &str)
            .optimize_tables_for_write_performance() // optional
            .wrap_primary_key_on_overflow(), // optional
    ) {
        panic!("Conversion to sql 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, Protobuf and SQL

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,
}

// only with the feature "async-psql": Insert and query functions for async PostgreSQL
impl Header {
    pub async fn apsql_retrieve_many(context: &apsql::Context<'_>, ids: &[i32]) -> Result<Vec<Self>, apsql::Error> { /*..*/ }
    pub async fn apsql_retrieve(context: &apsql::Context<'_>, id: i32) -> Result<Self, apsql::Error> { /*..*/ }
    pub async fn apsql_load(context: &apsql::Context<'_>, row: &apsql::Row) -> Result<Self, apsql::Error> { /*..*/ }
    pub async fn apsql_insert(&self, context: &apsql::Context<'_>) -> Result<i32, apsql::PsqlError> { /*..*/ }
}

// only with the feature "psql": Insert and query functions for non-async PostgreSQL
impl PsqlRepresentable for Header { /*..*/ }
impl PsqlInsertable for Header { /*..*/ }
impl PsqlQueryable for Header { /*..*/ }

The generated protobuf file (optional):

syntax = 'proto3';
package my.messages;

message Header {
    uint32 timestamp = 1;
}

The generated SQL file (optional):

DROP TABLE IF EXISTS Header CASCADE;

CREATE TABLE Header (
    id SERIAL PRIMARY KEY,
    timestamp INTEGER NOT NULL
);

Example: Usage of async postgres

NOTE: This requires the async-psql feature.

Using async postgres allows the message - or the batched messages - to take advantage of pipelining. This can provide a significant speedup for deep message types (personal experience this is around 26%) compared to the synchronous/blocking postgres implementation.

use asn1rs::io::async_psql::*;
use tokio_postgres::NoTls;

#[tokio::main]
async fn main() {
    let transactional = true;
    let (mut client, connection) = tokio_postgres::connect(
        "host=localhost user=postgres application_name=psql_async_demo",
        NoTls,
    )
        .await
        .expect("Failed to connect");

    tokio::spawn(connection);
  

    let context = if transactional {
        let transaction = client
            .transaction()
            .await
            .expect("Failed to open a new transaction");
        Cache::default().into_transaction_context(transaction)
    } else {
        Cache::default().into_client_context(client)
    };

    // using sample message from above
    let message = Header {
        timestamp: 1234,
    };
   
    // This issues all necessary insert statements on the given Context and
    // because it does not require exclusive access to the context, you can
    // issue multiple inserts and await them concurrently with for example
    // tokio::try_join, futures::try_join_all or the like. 
    let id = message.apsql_insert(&context).await.expect("Insert failed");
    
    // This disassembles the context, allowing the Transaction to be committed
    // or rolled back. This operation also optimizes the read access to
    // prepared statements of the Cache. If you do not want to do that, then call
    // Context::split_unoptimized instead.
    // You can also call `Cache::optimize()` manually to optimize the read access
    // to the cached prepared statements.
    // See the doc for more information about the usage of cached prepared statements
    let (mut cache, transaction) = context.split();
   
    // this is (logically) a nop on a non-transactional context
    transaction.commit().await.expect("failed to commit");

    let context = if transactional {
        let transaction = client
            .transaction()
            .await
            .expect("Failed to open a new transaction");
        Cache::default().into_transaction_context(transaction)
    } else {
        Cache::default().into_client_context(client)
    };

    let message_from_db = Header::apsql_retrieve(&context, id).await.expect("Failed to load");
    assert_eq!(message, message_from_db);
}

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):

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
• remove legacy rust+uper code generator (v0.3.0)
• 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