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/*
* ppbloom.c - Ping-Pong Bloom Filter for nonce reuse detection
*
* Copyright (C) 2013 - 2018, Max Lv <max.c.lv@gmail.com>
*
* This file is part of the shadowsocks-libev.
*
* shadowsocks-libev is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* shadowsocks-libev is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with shadowsocks-libev; see the file COPYING. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <stdlib.h>
#include "bloom.h"
#include "ppbloom.h"
#include "utils.h"
#define PING 0
#define PONG 1
static struct bloom ppbloom[2];
static int bloom_count[2];
static int current;
static int entries;
static double error;
int
ppbloom_init(int n, double e)
{
int err;
entries = n / 2;
error = e;
err = bloom_init(ppbloom + PING, entries, error);
if (err)
return err;
err = bloom_init(ppbloom + PONG, entries, error);
if (err)
return err;
bloom_count[PING] = 0;
bloom_count[PONG] = 0;
current = PING;
return 0;
}
int
ppbloom_check(const void *buffer, int len)
{
int ret;
ret = bloom_check(ppbloom + PING, buffer, len);
if (ret)
return ret;
ret = bloom_check(ppbloom + PONG, buffer, len);
if (ret)
return ret;
return 0;
}
int
ppbloom_add(const void *buffer, int len)
{
int err;
err = bloom_add(ppbloom + current, buffer, len);
if (err == -1)
return err;
bloom_count[current]++;
if (bloom_count[current] >= entries) {
bloom_count[current] = 0;
current = current == PING ? PONG : PING;
bloom_free(ppbloom + current);
bloom_init(ppbloom + current, entries, error);
}
return 0;
}
void
ppbloom_free()
{
bloom_free(ppbloom + PING);
bloom_free(ppbloom + PONG);
}