1 //! Helper module to compute a CRC32 checksum
2
3 use std::io;
4 use std::io::prelude::*;
5
6 const CRC32_TABLE : [u32; 256] = [
7 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
8 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
9 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
10 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
11 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
12 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
13 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
14 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
15 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
16 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
17 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
18 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
19 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
20 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
21 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
22 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
23 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
24 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
25 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
26 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
27 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
28 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
29 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
30 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
31 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
32 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
33 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
34 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
35 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
36 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
37 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
38 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
39 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
40 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
41 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
42 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
43 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
44 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
45 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
46 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
47 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
48 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
49 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
50 ];
51
52 /// Update the checksum prev based upon the contents of buf.
update(prev: u32, buf: &[u8]) -> u3253 pub fn update(prev: u32, buf: &[u8]) -> u32
54 {
55 let mut crc = !prev;
56
57 for &byte in buf.iter()
58 {
59 crc = CRC32_TABLE[((crc as u8) ^ byte) as usize] ^ (crc >> 8);
60 }
61
62 !crc
63 }
64
65 /// Reader that validates the CRC32 when it reaches the EOF.
66 pub struct Crc32Reader<R>
67 {
68 inner: R,
69 crc: u32,
70 check: u32,
71 }
72
73 impl<R> Crc32Reader<R>
74 {
75 /// Get a new Crc32Reader which check the inner reader against checksum.
new(inner: R, checksum: u32) -> Crc32Reader<R>76 pub fn new(inner: R, checksum: u32) -> Crc32Reader<R>
77 {
78 Crc32Reader
79 {
80 inner: inner,
81 crc: 0,
82 check: checksum,
83 }
84 }
85
check_matches(&self) -> bool86 fn check_matches(&self) -> bool
87 {
88 self.check == self.crc
89 }
90
into_inner(self) -> R91 pub fn into_inner(self) -> R {
92 self.inner
93 }
94 }
95
96 impl<R: Read> Read for Crc32Reader<R>
97 {
read(&mut self, buf: &mut [u8]) -> io::Result<usize>98 fn read(&mut self, buf: &mut [u8]) -> io::Result<usize>
99 {
100 let count = match self.inner.read(buf)
101 {
102 Ok(0) if !self.check_matches() => { return Err(io::Error::new(io::ErrorKind::Other, "Invalid checksum")) },
103 Ok(n) => n,
104 Err(e) => return Err(e),
105 };
106 self.crc = update(self.crc, &buf[0..count]);
107 Ok(count)
108 }
109 }
110
111 #[cfg(test)]
112 mod test {
113 #[test]
samples()114 fn samples() {
115 assert_eq!(super::update(0, b""), 0);
116
117 // test vectors from the iPXE project (input and output are bitwise negated)
118 assert_eq!(super::update(!0x12345678, b""), !0x12345678);
119 assert_eq!(super::update(!0xffffffff, b"hello world"), !0xf2b5ee7a);
120 assert_eq!(super::update(!0xffffffff, b"hello"), !0xc9ef5979);
121 assert_eq!(super::update(!0xc9ef5979, b" world"), !0xf2b5ee7a);
122
123 // Some vectors found on Rosetta code
124 assert_eq!(super::update(0, b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"), 0x190A55AD);
125 assert_eq!(super::update(0, b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF"), 0xFF6CAB0B);
126 assert_eq!(super::update(0, b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F"), 0x91267E8A);
127 }
128 }
129