mirror of
https://github.com/ferrous-systems/embedded-trainings-2020.git
synced 2024-09-26 13:30:07 +00:00
99 lines
2.6 KiB
Rust
99 lines
2.6 KiB
Rust
#![deny(unused_must_use)]
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#![no_main]
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#![no_std]
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use core::str;
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use cortex_m_rt::entry;
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use dk::ieee802154::{Channel, Packet};
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use heapless::{consts, LinearMap, Vec};
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use panic_log as _; // the panicking behavior
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const TEN_MS: u32 = 10_000;
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#[entry]
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fn main() -> ! {
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let board = dk::init().unwrap();
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let mut radio = board.radio;
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let mut timer = board.timer;
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// puzzle.hex uses channel 25
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radio.set_channel(Channel::_25);
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/* # Build a dictionary */
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let mut dict = LinearMap::<u8, u8, consts::U128>::new();
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// ^^^^^^^^^^^^ NOTE larger capacity
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let mut packet = Packet::new();
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for plainletter in 0..=127 {
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// ^^^^^^^ NOTE complete ASCII range
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packet.copy_from_slice(&[plainletter]);
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radio.send(&packet);
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if radio.recv_timeout(&mut packet, &mut timer, TEN_MS).is_ok() {
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// response should be one byte large
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if packet.len() == 1 {
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let cipherletter = packet[0];
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// NOTE we want to map in reverse: from cipherletter to plainletter
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dict.insert(cipherletter, plainletter)
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.expect("dictionary full");
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} else {
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log::error!("response packet was not a single byte");
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dk::exit()
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}
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} else {
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log::error!("no response or response packet was corrupted");
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dk::exit()
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}
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}
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/* # Retrieve the secret string */
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packet.copy_from_slice(&[]); // empty packet
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radio.send(&packet);
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if radio.recv_timeout(&mut packet, &mut timer, TEN_MS).is_err() {
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log::error!("no response or response packet was corrupted");
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dk::exit()
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}
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log::info!(
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"ciphertext: {}",
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str::from_utf8(&packet).expect("packet was not valid UTF-8")
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);
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/* # Decrypt the string */
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let mut buffer = Vec::<u8, consts::U128>::new();
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// iterate over the bytes
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for cipherletter in packet.iter() {
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let key = cipherletter;
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let value = dict[key];
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let plainletter = value;
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buffer.push(plainletter).expect("buffer full");
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}
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log::info!(
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"plaintext: {}",
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str::from_utf8(&buffer).expect("buffer contains non-UTF-8 data")
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);
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/* # Verify decrypted text */
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packet.copy_from_slice(&buffer);
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radio.send(&packet);
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if radio.recv_timeout(&mut packet, &mut timer, TEN_MS).is_err() {
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log::error!("no response or response packet was corrupted");
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dk::exit()
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}
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log::info!(
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"Dongle response: {}",
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str::from_utf8(&packet).expect("response was not UTF-8")
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);
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dk::exit()
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}
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