Trait x509_parser::prelude::FromDer

source · [−]
pub trait FromDer<'a, E = Error> {
    fn from_der(bytes: &'a [u8]) -> Result<(&'a [u8], Self), Err<E>>;
}
Expand description

Base trait for DER object parsers

Library authors should usually not directly implement this trait, but should prefer implementing the TryFrom<Any> + CheckDerConstraints traits, which offers greater flexibility and provides an equivalent FromDer implementation for free (in fact, it provides both FromBer and FromDer).

Note: if you already implemented TryFrom<Any> and CheckDerConstraints, you can get a free FromDer implementation by implementing the DerAutoDerive trait. This is not automatic, so it is also possible to manually implement FromDer if preferred.

Examples

use asn1_rs::{Any, CheckDerConstraints, DerAutoDerive, Result, Tag};
use std::convert::TryFrom;

// The type to be decoded
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct MyType(pub u32);

impl<'a> TryFrom<Any<'a>> for MyType {
    type Error = asn1_rs::Error;

    fn try_from(any: Any<'a>) -> Result<MyType> {
        any.tag().assert_eq(Tag::Integer)?;
        // for this fictive example, the type contains the number of characters
        let n = any.data.len() as u32;
        Ok(MyType(n))
    }
}

impl CheckDerConstraints for MyType {
    fn check_constraints(any: &Any) -> Result<()> {
        any.header.assert_primitive()?;
        Ok(())
    }
}

impl DerAutoDerive for MyType {}

// The above code provides a `FromDer` implementation for free.

// Example of parsing code:
use asn1_rs::FromDer;

let input = &[2, 1, 2];
// Objects can be parsed using `from_der`, which returns the remaining bytes
// and the parsed object:
let (rem, my_type) = MyType::from_der(input).expect("parsing failed");

Required Methods

Attempt to parse input bytes into a DER object (enforcing constraints)

Implementations on Foreign Types

manual impl of FromDer, so we do not need to require TryFrom + CheckDerConstraints

manual impl of FromDer, so we do not need to require TryFrom + CheckDerConstraints

manual impl of FromDer, so we do not need to require TryFrom + CheckDerConstraints

Implementors

CertificationRequest ::= SEQUENCE {
    certificationRequestInfo CertificationRequestInfo,
    signatureAlgorithm AlgorithmIdentifier{{ SignatureAlgorithms }},
    signature          BIT STRING
}

CertificationRequestInfo ::= SEQUENCE {
     version       INTEGER { v1(0) } (v1,...),
     subject       Name,
     subjectPKInfo SubjectPublicKeyInfo{{ PKInfoAlgorithms }},
     attributes    [0] Attributes{{ CRIAttributes }}
}

Extension  ::=  SEQUENCE  {
    extnID      OBJECT IDENTIFIER,
    critical    BOOLEAN DEFAULT FALSE,
    extnValue   OCTET STRING  }

CertificateList  ::=  SEQUENCE  {
     tbsCertList          TBSCertList,
     signatureAlgorithm   AlgorithmIdentifier,
     signatureValue       BIT STRING  }