matrix-rust-sdk

// Copyright 2021 The Matrix.org Foundation C.I.C.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

use qrcode::{EcLevel, QrCode, Version, bits::Bits};

use ruma::serde::Base64;

use vodozemac::Ed25519PublicKey;

use crate::error::EncodingError;

pub(crate) const HEADER: &[u8] = b"MATRIX";

pub(crate) const VERSION: u8 = 0x2;

pub(crate) const MAX_MODE: u8 = 0x2;

pub(crate) const MIN_SECRET_LEN: usize = 8;

pub(crate) fn to_bytes(

    mode: u8,

    flow_id: &str,

    first_key: Ed25519PublicKey,

    second_key: Ed25519PublicKey,

    shared_secret: &Base64,

) -> Result<Vec<u8>, EncodingError> {

    let flow_id_len: u16 = flow_id.len().try_into()?;

    let flow_id_len = flow_id_len.to_be_bytes();

    let data = [

        HEADER,

        &[VERSION],

        &[mode],

        flow_id_len.as_ref(),

        flow_id.as_bytes(),

        first_key.as_bytes(),

        second_key.as_bytes(),

        shared_secret.as_bytes(),

    ]

    .concat();

    Ok(data)

}

pub(crate) fn to_qr_code(

    mode: u8,

    flow_id: &str,

    first_key: Ed25519PublicKey,

    second_key: Ed25519PublicKey,

    shared_secret: &Base64,

) -> Result<QrCode, EncodingError> {

    let data = to_bytes(mode, flow_id, first_key, second_key, shared_secret)?;

    // Mobile clients seem to have trouble decoding the QR code that gets

    // generated by `QrCode::new()` it seems to add a couple of data segments

    // with different data modes/types. The parsers seem to assume a single

    // data type and since we start with an ASCII `MATRIX` header the rest of

    // the data gets treated as a string as well.

    //

    // We make sure that there isn't an ECI bit set and we just push the bytes,

    // this seems to help since the decoder doesn't assume an encoding and

    // treats everything as raw bytes.

    let mut bits = Bits::new(Version::Normal(7));

    bits.push_byte_data(&data)?;

    bits.push_terminator(EcLevel::L)?;

    Ok(QrCode::with_bits(bits, EcLevel::L)?)

}