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//! ASN.1 `BOOLEAN` support.
use crate::{
asn1::AnyRef, ord::OrdIsValueOrd, DecodeValue, EncodeValue, Error, ErrorKind, FixedTag, Header,
Length, Reader, Result, Tag, Writer,
};
/// Byte used to encode `true` in ASN.1 DER. From X.690 Section 11.1:
///
/// > If the encoding represents the boolean value TRUE, its single contents
/// > octet shall have all eight bits set to one.
const TRUE_OCTET: u8 = 0b11111111;
/// Byte used to encode `false` in ASN.1 DER.
const FALSE_OCTET: u8 = 0b00000000;
impl<'a> DecodeValue<'a> for bool {
fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
if header.length != Length::ONE {
return Err(reader.error(ErrorKind::Length { tag: Self::TAG }));
}
match reader.read_byte()? {
FALSE_OCTET => Ok(false),
TRUE_OCTET => Ok(true),
_ => Err(Self::TAG.non_canonical_error()),
}
}
}
impl EncodeValue for bool {
fn value_len(&self) -> Result<Length> {
Ok(Length::ONE)
}
fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
writer.write_byte(if *self { TRUE_OCTET } else { FALSE_OCTET })
}
}
impl FixedTag for bool {
const TAG: Tag = Tag::Boolean;
}
impl OrdIsValueOrd for bool {}
impl TryFrom<AnyRef<'_>> for bool {
type Error = Error;
fn try_from(any: AnyRef<'_>) -> Result<bool> {
any.try_into()
}
}
#[cfg(test)]
mod tests {
use crate::{Decode, Encode};
#[test]
fn decode() {
assert_eq!(true, bool::from_der(&[0x01, 0x01, 0xFF]).unwrap());
assert_eq!(false, bool::from_der(&[0x01, 0x01, 0x00]).unwrap());
}
#[test]
fn encode() {
let mut buffer = [0u8; 3];
assert_eq!(
&[0x01, 0x01, 0xFF],
true.encode_to_slice(&mut buffer).unwrap()
);
assert_eq!(
&[0x01, 0x01, 0x00],
false.encode_to_slice(&mut buffer).unwrap()
);
}
#[test]
fn reject_non_canonical() {
assert!(bool::from_der(&[0x01, 0x01, 0x01]).is_err());
}
}
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