Re-import of fprobe-ulog

[iptables.git] / src / hash.c

diff --git a/src/hash.c b/src/hash.c
new file mode 100644 (file)
index 0000000..15a62ed
--- /dev/null
+++ b/src/hash.c
@@ -0,0 +1,94 @@
+/*
+       Copyright (C) Slava Astashonok <sla@0n.ru>
+
+       This program is free software; you can redistribute it and/or
+       modify it under the terms of the GNU General Public License.
+
+       $Id: hash.c,v 1.3.2.2.2.1 2005/01/29 19:30:41 sla Exp $
+*/
+
+#include <common.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+
+#include <hash.h>
+
+
+#ifdef HASH_TYPE_CRC
+static uint16_t crc16_poly;
+static uint8_t shuffle_table[256];
+static uint16_t crc16_table[256];
+
+uint16_t crc16(uint16_t crc, uint8_t val)
+{
+       int i;
+
+       crc ^= val << 8;
+       for (i = 8; i--; )
+               crc = crc & 0x8000 ? (crc << 1) ^ crc16_poly : crc << 1;
+       return crc;
+}
+#endif
+
+hash_t hash(void *p, int size)
+{
+       /*
+       ?FIXME?
+       Check for valid size (> 0)
+       */
+
+       hash_t hash = 0;
+
+#if defined HASH_TYPE_XOR && HASH_BITS == 16
+       if (size & 1) hash = *((uint8_t *) p++);
+       size >>= 1;
+#endif
+
+       for (;size--;) {
+#ifdef HASH_TYPE_XOR
+               hash ^= *((hash_t *) p++);
+# if HASH_BITS == 16
+               p++;
+# endif
+#endif
+#ifdef HASH_TYPE_CRC
+               hash = crc16_table[shuffle_table[*((uint8_t *) p++)] \
+                       ^ (hash >> 8)] ^ (hash << 8);
+#endif
+       }
+       return hash;
+}
+
+void hash_init()
+{
+
+#ifdef HASH_TYPE_CRC
+       int rnd, i, j, m;
+       FILE *rnddev;
+
+       if ((rnddev = fopen(RNDDEV, "r"))) {
+               fcntl(fileno(rnddev), F_SETFL, \
+                       fcntl(fileno(rnddev), F_GETFL) | O_NONBLOCK);
+               fread(&rnd, sizeof(rnd), 1, rnddev);
+               fclose(rnddev);
+       }
+       srand(time(NULL) ^ getpid() ^ rnd);
+       crc16_poly = rand() | 1;
+
+       for (i = 0; i < 256; i++) {
+           crc16_table[i] = crc16(0, i);
+           shuffle_table[i] = i;
+       }
+
+       for (i = 0; i < 256; i++) {
+           j = (int) (256.0 * rand() / (RAND_MAX + 1.0));
+           m = shuffle_table[i];
+           shuffle_table[i] = shuffle_table[j];
+           shuffle_table[j] = m;
+       }
+#endif
+}