openpgp-card 0.4.2

A client implementation for the OpenPGP card specification
Documentation 
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// SPDX-FileCopyrightText: 2021 Heiko Schaefer <heiko@schaefer.name>
// SPDX-License-Identifier: MIT OR Apache-2.0

//! 4.1.3.1 Extended length information
//! (Introduced in V3.0)

use std::convert::TryFrom;

use nom::{bytes::complete::tag, number::complete as number, sequence};

use crate::card_do::{complete, ExtendedLengthInfo};

fn parse(input: &[u8]) -> nom::IResult<&[u8], (u16, u16)> {
    let (input, (_, cmd, _, resp)) = nom::combinator::all_consuming(sequence::tuple((
        tag([0x2, 0x2]),
        number::be_u16,
        tag([0x2, 0x2]),
        number::be_u16,
    )))(input)?;

    Ok((input, (cmd, resp)))
}

impl ExtendedLengthInfo {
    pub fn max_command_bytes(&self) -> u16 {
        self.max_command_bytes
    }

    pub fn max_response_bytes(&self) -> u16 {
        self.max_response_bytes
    }
}

impl TryFrom<&[u8]> for ExtendedLengthInfo {
    type Error = crate::Error;

    fn try_from(input: &[u8]) -> Result<Self, Self::Error> {
        let eli = complete(parse(input))?;

        Ok(Self {
            max_command_bytes: eli.0,
            max_response_bytes: eli.1,
        })
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_floss34() {
        let data = [0x2, 0x2, 0x8, 0x0, 0x2, 0x2, 0x8, 0x0];

        let eli =
            ExtendedLengthInfo::try_from(&data[..]).expect("failed to parse extended length info");

        assert_eq!(
            eli,
            ExtendedLengthInfo {
                max_command_bytes: 2048,
                max_response_bytes: 2048,
            },
        );
    }
}