pub trait FromDer<'a>: Sized {
// Required method
fn from_der(bytes: &'a [u8]) -> Result<(&'a [u8], Self), Err<Error>>;
}Available on crate feature
mtls only.Expand description
Base trait for DER object parsers
Library authors should usually not directly implement this trait, but should prefer implementing the
TryFrom<Any> + CheckDerConstraint 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> to get the FromBer implementation, then you only
have to add a CheckDerConstraint implementation.
§Examples
use asn1_rs::{Any, CheckDerConstraints, 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(())
}
}
// 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§
Object Safety§
This trait is not object safe.