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//! X.509 `AlgorithmIdentifier`
use crate::{Error, Result};
use core::cmp::Ordering;
use der::asn1::{AnyRef, ObjectIdentifier};
use der::{Decode, DecodeValue, DerOrd, Encode, Header, Reader, Sequence, ValueOrd};
/// X.509 `AlgorithmIdentifier` as defined in [RFC 5280 Section 4.1.1.2].
///
/// ```text
/// AlgorithmIdentifier ::= SEQUENCE {
/// algorithm OBJECT IDENTIFIER,
/// parameters ANY DEFINED BY algorithm OPTIONAL }
/// ```
///
/// [RFC 5280 Section 4.1.1.2]: https://tools.ietf.org/html/rfc5280#section-4.1.1.2
#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
pub struct AlgorithmIdentifier<'a> {
/// Algorithm OID, i.e. the `algorithm` field in the `AlgorithmIdentifier`
/// ASN.1 schema.
pub oid: ObjectIdentifier,
/// Algorithm `parameters`.
pub parameters: Option<AnyRef<'a>>,
}
impl<'a> AlgorithmIdentifier<'a> {
/// Assert the `algorithm` OID is an expected value.
pub fn assert_algorithm_oid(&self, expected_oid: ObjectIdentifier) -> Result<ObjectIdentifier> {
if self.oid == expected_oid {
Ok(expected_oid)
} else {
Err(Error::OidUnknown { oid: expected_oid })
}
}
/// Assert `parameters` is an OID and has the expected value.
pub fn assert_parameters_oid(
&self,
expected_oid: ObjectIdentifier,
) -> Result<ObjectIdentifier> {
let actual_oid = self.parameters_oid()?;
if actual_oid == expected_oid {
Ok(actual_oid)
} else {
Err(Error::OidUnknown { oid: expected_oid })
}
}
/// Assert the values of the `algorithm` and `parameters` OIDs.
pub fn assert_oids(
&self,
algorithm: ObjectIdentifier,
parameters: ObjectIdentifier,
) -> Result<()> {
self.assert_algorithm_oid(algorithm)?;
self.assert_parameters_oid(parameters)?;
Ok(())
}
/// Get the `parameters` field as an [`AnyRef`].
///
/// Returns an error if `parameters` are `None`.
pub fn parameters_any(&self) -> Result<AnyRef<'a>> {
self.parameters.ok_or(Error::AlgorithmParametersMissing)
}
/// Get the `parameters` field as an [`ObjectIdentifier`].
///
/// Returns an error if it is absent or not an OID.
pub fn parameters_oid(&self) -> Result<ObjectIdentifier> {
Ok(ObjectIdentifier::try_from(self.parameters_any()?)?)
}
/// Convert to a pair of [`ObjectIdentifier`]s.
///
/// This method is helpful for decomposing in match statements. Note in
/// particular that `NULL` parameters are treated the same as missing
/// parameters.
///
/// Returns an error if parameters are present but not an OID.
pub fn oids(&self) -> der::Result<(ObjectIdentifier, Option<ObjectIdentifier>)> {
Ok((
self.oid,
match self.parameters {
None => None,
Some(p) => match p {
AnyRef::NULL => None,
_ => Some(p.oid()?),
},
},
))
}
}
impl<'a> DecodeValue<'a> for AlgorithmIdentifier<'a> {
fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> der::Result<Self> {
reader.read_nested(header.length, |reader| {
Ok(Self {
oid: reader.decode()?,
parameters: reader.decode()?,
})
})
}
}
impl<'a> Sequence<'a> for AlgorithmIdentifier<'a> {
fn fields<F, T>(&self, f: F) -> der::Result<T>
where
F: FnOnce(&[&dyn Encode]) -> der::Result<T>,
{
f(&[&self.oid, &self.parameters])
}
}
impl<'a> TryFrom<&'a [u8]> for AlgorithmIdentifier<'a> {
type Error = Error;
fn try_from(bytes: &'a [u8]) -> Result<Self> {
Ok(Self::from_der(bytes)?)
}
}
impl ValueOrd for AlgorithmIdentifier<'_> {
fn value_cmp(&self, other: &Self) -> der::Result<Ordering> {
match self.oid.der_cmp(&other.oid)? {
Ordering::Equal => self.parameters.der_cmp(&other.parameters),
other => Ok(other),
}
}
}
|
