Initial commit of Ccnet server.

lib/bloom-filter.c

@@ -0,0 +1,176 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+#include <limits.h>
+#include <stdint.h>
+#include <string.h>
+#include <openssl/sha.h>
+#include <assert.h>
+
+#include "bloom-filter.h"
+
+#define SETBIT(a, n) (a[n/CHAR_BIT] |= (1<<(n%CHAR_BIT)))
+#define CLEARBIT(a, n) (a[n/CHAR_BIT] &= ~(1<<(n%CHAR_BIT)))
+#define GETBIT(a, n) (a[n/CHAR_BIT] & (1<<(n%CHAR_BIT)))
+
+Bloom* bloom_create(size_t size, int k, int counting)
+{
+    Bloom *bloom;
+    size_t csize = 0;
+
+    if (k <=0 || k > 10) return NULL;
+    
+    if ( !(bloom = malloc(sizeof(Bloom))) ) return NULL;
+    if ( !(bloom->a = calloc((size+CHAR_BIT-1)/CHAR_BIT, sizeof(char))) )
+    {
+        free (bloom);
+        return NULL;
+    }
+    if (counting) {
+        csize = size*4;
+        bloom->counters = calloc((csize+CHAR_BIT-1)/CHAR_BIT, sizeof(char));
+        if (!bloom->counters) {
+            free (bloom);
+            return NULL;
+        }
+    }
+
+    bloom->asize = size;
+    bloom->csize = csize;
+    bloom->k = k;
+    bloom->counting = counting;
+
+    return bloom;
+}
+
+int bloom_destroy(Bloom *bloom)
+{
+    free (bloom->a);
+    if (bloom->counting) free (bloom->counters);
+    free (bloom);
+
+    return 0;
+}
+
+static void
+incr_bit (Bloom *bf, unsigned int bit_idx)
+{
+    unsigned int char_idx, offset;
+    unsigned char value;
+    unsigned int high;
+    unsigned int low;
+
+    SETBIT (bf->a, bit_idx);
+
+    if (!bf->counting) return;
+
+    char_idx = bit_idx / 2;
+    offset = bit_idx % 2;
+
+    value = bf->counters[char_idx];
+    low = value & 0xF;
+    high = (value & 0xF0) >> 4;
+
+    if (offset == 0) {
+        if (low < 0xF)
+            low++;
+    } else {
+        if (high < 0xF)
+            high++;
+    }
+    value = ((high << 4) | low);
+
+    bf->counters[char_idx] = value;
+}
+
+static void
+decr_bit (Bloom *bf, unsigned int bit_idx)
+{
+    unsigned int char_idx, offset;
+    unsigned char value;
+    unsigned int high;
+    unsigned int low;
+
+    if (!bf->counting) {
+        CLEARBIT (bf->a, bit_idx);
+        return;
+    }
+
+    char_idx = bit_idx / 2;
+    offset = bit_idx % 2;
+
+    value = bf->counters[char_idx];
+    low = value & 0xF;
+    high = (value & 0xF0) >> 4;
+
+    /* decrement, but once we have reached the max, never go back! */
+    if (offset == 0) {
+        if ((low > 0) && (low < 0xF))
+            low--;
+        if (low == 0) {
+            CLEARBIT (bf->a, bit_idx);
+        }
+    } else {
+        if ((high > 0) && (high < 0xF))
+            high--;
+        if (high == 0) {
+            CLEARBIT (bf->a, bit_idx);
+        }
+    }
+    value = ((high << 4) | low);
+
+    bf->counters[char_idx] = value;
+}
+
+int bloom_add(Bloom *bloom, const char *s)
+{
+    int i;
+    SHA_CTX c;
+    unsigned char sha1[20];
+    int16_t *sha_int = (int16_t *)&sha1;
+    
+    SHA1_Init(&c);
+    SHA1_Update(&c, s, strlen(s));
+    SHA1_Final (sha1, &c);
+    
+    for (i=0; i < bloom->k; ++i)
+        incr_bit (bloom, sha_int[i] % bloom->asize);
+
+    return 0;
+}
+
+int bloom_remove(Bloom *bloom, const char *s)
+{
+    int i;
+    SHA_CTX c;
+    unsigned char sha1[20];
+    int16_t *sha_int = (int16_t *)&sha1;
+    
+    if (!bloom->counting)
+        return -1;
+
+    SHA1_Init(&c);
+    SHA1_Update(&c, s, strlen(s));
+    SHA1_Final (sha1, &c);
+    
+    for (i=0; i < bloom->k; ++i)
+        decr_bit (bloom, sha_int[i] % bloom->asize);
+
+    return 0;
+}
+
+int bloom_test(Bloom *bloom, const char *s)
+{
+    int i;
+    SHA_CTX c;
+    unsigned char sha1[20];
+    int16_t *sha_int = (int16_t *)&sha1;
+    
+    SHA1_Init(&c);
+    SHA1_Update(&c, s, strlen(s));
+    SHA1_Final (sha1, &c);
+    
+    for (i=0; i < bloom->k; ++i)
+        if(!(GETBIT(bloom->a, sha_int[i] % bloom->asize))) return 0;
+
+    return 1;
+}