nkeys/
crc.rs

1use super::error::{Error, ErrorKind};
2use super::Result;
3
4const CRC_TABLE: [u16; 256] = [
5    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 0x8108, 0x9129, 0xa14a, 0xb16b,
6    0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
7    0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 0x2462, 0x3443, 0x0420, 0x1401,
8    0x64e6, 0x74c7, 0x44a4, 0x5485, 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
9    0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 0xb75b, 0xa77a, 0x9719, 0x8738,
10    0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
11    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 0x5af5, 0x4ad4, 0x7ab7, 0x6a96,
12    0x1a71, 0x0a50, 0x3a33, 0x2a12, 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
13    0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 0xedae, 0xfd8f, 0xcdec, 0xddcd,
14    0xad2a, 0xbd0b, 0x8d68, 0x9d49, 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
15    0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 0x9188, 0x81a9, 0xb1ca, 0xa1eb,
16    0xd10c, 0xc12d, 0xf14e, 0xe16f, 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
17    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 0x02b1, 0x1290, 0x22f3, 0x32d2,
18    0x4235, 0x5214, 0x6277, 0x7256, 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
19    0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 0xa7db, 0xb7fa, 0x8799, 0x97b8,
20    0xe75f, 0xf77e, 0xc71d, 0xd73c, 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
21    0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 0x5844, 0x4865, 0x7806, 0x6827,
22    0x18c0, 0x08e1, 0x3882, 0x28a3, 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
23    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d,
24    0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
25    0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 0x6e17, 0x7e36, 0x4e55, 0x5e74,
26    0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
27];
28
29pub(crate) fn crc16(data: &[u8]) -> u16 {
30    let mut crc = 0_u16;
31    for b in data {
32        let idx = ((crc >> 8) ^ *b as u16) & 0x00FF;
33        crc = (crc << 8) ^ CRC_TABLE[idx as usize];
34    }
35    crc
36}
37
38pub(crate) fn valid_checksum(data: &[u8], expected: u16) -> bool {
39    crc16(data) == expected
40}
41
42pub(crate) fn push_crc(data: &mut Vec<u8>) {
43    let crc = crc16(data);
44    data.extend(u16::to_le_bytes(crc));
45}
46
47pub(crate) fn extract_crc(data: &mut Vec<u8>) -> Result<u16> {
48    let data_len = data.len().checked_sub(2).ok_or_else(|| {
49        Error::new(
50            ErrorKind::ChecksumFailure,
51            Some("CRC data vector contains less than two characters"),
52        )
53    })?;
54
55    let crc = u16::from_le_bytes(data[data_len..].try_into().unwrap());
56    data.truncate(data_len);
57    Ok(crc)
58}
59
60#[cfg(test)]
61mod tests {
62    use super::{crc16, extract_crc, push_crc, valid_checksum};
63
64    #[test]
65    fn e2e() {
66        let mut raw_data = rand::random::<[u8; 32]>();
67        let data_crc = crc16(&raw_data);
68
69        let mut data = raw_data.to_vec();
70        push_crc(&mut data);
71
72        let crc = extract_crc(&mut data).unwrap();
73        assert_eq!(raw_data, data.as_slice());
74        assert_eq!(data_crc, crc);
75        assert!(valid_checksum(&raw_data, data_crc));
76
77        raw_data[17] = raw_data[17].wrapping_sub(1);
78        assert!(!valid_checksum(&raw_data, data_crc));
79    }
80}
nkeys/crc.rs

nkeys/
crc.rs
