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101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* A bloom filter.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "sslbloom.h"
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#include "prnetdb.h"
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#include "secport.h"
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#ifdef _MSC_VER
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#if _MSC_VER < 1900
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#define inline
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#endif
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#endif
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static inline unsigned int
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sslBloom_Size(unsigned int bits)
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{
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return (bits >= 3) ? (1 << (bits - 3)) : 1;
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}
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SECStatus
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sslBloom_Init(sslBloomFilter *filter, unsigned int k, unsigned int bits)
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{
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PORT_Assert(filter);
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PORT_Assert(bits > 0);
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PORT_Assert(bits <= sizeof(PRUint32) * 8);
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PORT_Assert(k > 0);
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filter->filter = PORT_ZNewArray(PRUint8, sslBloom_Size(bits));
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if (!filter->filter) {
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return SECFailure; /* Error code already set. */
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}
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filter->k = k;
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filter->bits = bits;
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return SECSuccess;
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}
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void
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sslBloom_Zero(sslBloomFilter *filter)
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{
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PORT_Memset(filter->filter, 0, sslBloom_Size(filter->bits));
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}
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void
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sslBloom_Fill(sslBloomFilter *filter)
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{
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PORT_Memset(filter->filter, 0xff, sslBloom_Size(filter->bits));
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}
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static PRBool
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sslBloom_AddOrCheck(sslBloomFilter *filter, const PRUint8 *hashes, PRBool add)
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{
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unsigned int iteration;
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unsigned int bitIndex;
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PRUint32 tmp = 0;
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PRUint8 mask;
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unsigned int bytes = (filter->bits + 7) / 8;
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unsigned int shift = (bytes * 8) - filter->bits;
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PRBool found = PR_TRUE;
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PORT_Assert(bytes <= sizeof(unsigned int));
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for (iteration = 0; iteration < filter->k; ++iteration) {
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PORT_Memcpy(((PRUint8 *)&tmp) + (sizeof(tmp) - bytes),
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hashes, bytes);
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hashes += bytes;
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bitIndex = PR_ntohl(tmp) >> shift;
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mask = 1 << (bitIndex % 8);
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found = found && filter->filter[bitIndex / 8] & mask;
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if (add) {
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filter->filter[bitIndex / 8] |= mask;
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}
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}
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return found;
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}
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PRBool
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sslBloom_Add(sslBloomFilter *filter, const PRUint8 *hashes)
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{
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return sslBloom_AddOrCheck(filter, hashes, PR_TRUE);
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}
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PRBool
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sslBloom_Check(sslBloomFilter *filter, const PRUint8 *hashes)
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{
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return sslBloom_AddOrCheck(filter, hashes, PR_FALSE);
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}
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void
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sslBloom_Destroy(sslBloomFilter *filter)
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{
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PORT_Free(filter->filter);
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PORT_Memset(filter, 0, sizeof(*filter));
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}
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