diff options
Diffstat (limited to 'contrib/tcpdump/checksum.c')
| -rw-r--r-- | contrib/tcpdump/checksum.c | 67 |
1 files changed, 63 insertions, 4 deletions
diff --git a/contrib/tcpdump/checksum.c b/contrib/tcpdump/checksum.c index f441be3..da4718f 100644 --- a/contrib/tcpdump/checksum.c +++ b/contrib/tcpdump/checksum.c @@ -31,17 +31,73 @@ static const char rcsid[] _U_ = #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <assert.h> #include "interface.h" -#define CRC10_POLYNOMIAL 0x633 -static u_int16_t crc10_table[256]; +/* + * CRC-10 table generated using the following Python snippet: + +import sys + +crc_table = [] +for i in range(256): + accum = i << 2 + for j in range(8): + accum <<= 1 + if accum & 0x400: + accum ^= 0x633 + crc_table.append(accum) + +for i in range(len(crc_table)/8): + for j in range(8): + sys.stdout.write("0x%04x, " % crc_table[i*8+j]) + sys.stdout.write("\n") + + */ +static const u_int16_t crc10_table[256] = +{ + 0x0000, 0x0233, 0x0255, 0x0066, 0x0299, 0x00aa, 0x00cc, 0x02ff, + 0x0301, 0x0132, 0x0154, 0x0367, 0x0198, 0x03ab, 0x03cd, 0x01fe, + 0x0031, 0x0202, 0x0264, 0x0057, 0x02a8, 0x009b, 0x00fd, 0x02ce, + 0x0330, 0x0103, 0x0165, 0x0356, 0x01a9, 0x039a, 0x03fc, 0x01cf, + 0x0062, 0x0251, 0x0237, 0x0004, 0x02fb, 0x00c8, 0x00ae, 0x029d, + 0x0363, 0x0150, 0x0136, 0x0305, 0x01fa, 0x03c9, 0x03af, 0x019c, + 0x0053, 0x0260, 0x0206, 0x0035, 0x02ca, 0x00f9, 0x009f, 0x02ac, + 0x0352, 0x0161, 0x0107, 0x0334, 0x01cb, 0x03f8, 0x039e, 0x01ad, + 0x00c4, 0x02f7, 0x0291, 0x00a2, 0x025d, 0x006e, 0x0008, 0x023b, + 0x03c5, 0x01f6, 0x0190, 0x03a3, 0x015c, 0x036f, 0x0309, 0x013a, + 0x00f5, 0x02c6, 0x02a0, 0x0093, 0x026c, 0x005f, 0x0039, 0x020a, + 0x03f4, 0x01c7, 0x01a1, 0x0392, 0x016d, 0x035e, 0x0338, 0x010b, + 0x00a6, 0x0295, 0x02f3, 0x00c0, 0x023f, 0x000c, 0x006a, 0x0259, + 0x03a7, 0x0194, 0x01f2, 0x03c1, 0x013e, 0x030d, 0x036b, 0x0158, + 0x0097, 0x02a4, 0x02c2, 0x00f1, 0x020e, 0x003d, 0x005b, 0x0268, + 0x0396, 0x01a5, 0x01c3, 0x03f0, 0x010f, 0x033c, 0x035a, 0x0169, + 0x0188, 0x03bb, 0x03dd, 0x01ee, 0x0311, 0x0122, 0x0144, 0x0377, + 0x0289, 0x00ba, 0x00dc, 0x02ef, 0x0010, 0x0223, 0x0245, 0x0076, + 0x01b9, 0x038a, 0x03ec, 0x01df, 0x0320, 0x0113, 0x0175, 0x0346, + 0x02b8, 0x008b, 0x00ed, 0x02de, 0x0021, 0x0212, 0x0274, 0x0047, + 0x01ea, 0x03d9, 0x03bf, 0x018c, 0x0373, 0x0140, 0x0126, 0x0315, + 0x02eb, 0x00d8, 0x00be, 0x028d, 0x0072, 0x0241, 0x0227, 0x0014, + 0x01db, 0x03e8, 0x038e, 0x01bd, 0x0342, 0x0171, 0x0117, 0x0324, + 0x02da, 0x00e9, 0x008f, 0x02bc, 0x0043, 0x0270, 0x0216, 0x0025, + 0x014c, 0x037f, 0x0319, 0x012a, 0x03d5, 0x01e6, 0x0180, 0x03b3, + 0x024d, 0x007e, 0x0018, 0x022b, 0x00d4, 0x02e7, 0x0281, 0x00b2, + 0x017d, 0x034e, 0x0328, 0x011b, 0x03e4, 0x01d7, 0x01b1, 0x0382, + 0x027c, 0x004f, 0x0029, 0x021a, 0x00e5, 0x02d6, 0x02b0, 0x0083, + 0x012e, 0x031d, 0x037b, 0x0148, 0x03b7, 0x0184, 0x01e2, 0x03d1, + 0x022f, 0x001c, 0x007a, 0x0249, 0x00b6, 0x0285, 0x02e3, 0x00d0, + 0x011f, 0x032c, 0x034a, 0x0179, 0x0386, 0x01b5, 0x01d3, 0x03e0, + 0x021e, 0x002d, 0x004b, 0x0278, 0x0087, 0x02b4, 0x02d2, 0x00e1 +}; static void init_crc10_table(void) { +#define CRC10_POLYNOMIAL 0x633 register int i, j; register u_int16_t accum; + u_int16_t verify_crc10_table[256]; for ( i = 0; i < 256; i++ ) { @@ -50,9 +106,12 @@ init_crc10_table(void) { if ((accum <<= 1) & 0x400) accum ^= CRC10_POLYNOMIAL; } - crc10_table[i] = accum; + verify_crc10_table[i] = accum; } - return; + assert(memcmp(verify_crc10_table, + crc10_table, + sizeof(verify_crc10_table)) == 0); +#undef CRC10_POLYNOMIAL } u_int16_t |
