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/*
* Copyright (c) 2018-2023, OARC, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "tcpstate.h"
#include "iaddr.h"
#include "log.h"
#include "tcpreasm.h"
#define MAX_TCP_IDLE_TIME 600
#define MAX_TCP_IDLE_COUNT 4096
#define TCP_GC_TIME 60
tcpstate_ptr tcpstate_find(iaddr from, iaddr to, unsigned sport, unsigned dport, time_t t)
{
static time_t next_gc = 0;
tcpstate_ptr tcpstate;
#ifndef __clang_analyzer__
/* disabled during scan-build due to false-positives */
if (t >= next_gc || tcpstate_count > MAX_TCP_IDLE_COUNT) {
/* garbage collect stale states */
while ((tcpstate = TAIL(tcpstates)) && tcpstate->last_use < t - MAX_TCP_IDLE_TIME) {
tcpstate_discard(tcpstate, "gc stale");
}
next_gc = t + TCP_GC_TIME;
}
#endif
for (tcpstate = HEAD(tcpstates);
tcpstate != NULL;
tcpstate = NEXT(tcpstate, link)) {
if (ia_equal(tcpstate->saddr, from) && ia_equal(tcpstate->daddr, to) && tcpstate->sport == sport && tcpstate->dport == dport)
break;
}
if (tcpstate != NULL) {
tcpstate->last_use = t;
if (tcpstate != HEAD(tcpstates)) {
/* move to beginning of list */
UNLINK(tcpstates, tcpstate, link);
PREPEND(tcpstates, tcpstate, link);
}
}
return tcpstate;
}
tcpstate_ptr _curr_tcpstate = 0;
tcpstate_ptr tcpstate_new(iaddr from, iaddr to, unsigned sport, unsigned dport)
{
tcpstate_ptr tcpstate = calloc(1, sizeof *tcpstate);
if (tcpstate == NULL) {
/* Out of memory; recycle the least recently used */
logerr("warning: out of memory, "
"discarding some TCP state early");
tcpstate = TAIL(tcpstates);
assert(tcpstate != NULL);
UNLINK(tcpstates, tcpstate, link);
if (tcpstate->reasm) {
tcpreasm_free(tcpstate->reasm);
}
if (_curr_tcpstate == tcpstate) {
_curr_tcpstate = 0;
}
memset(tcpstate, 0, sizeof(*tcpstate));
} else {
tcpstate_count++;
}
tcpstate->saddr = from;
tcpstate->daddr = to;
tcpstate->sport = sport;
tcpstate->dport = dport;
INIT_LINK(tcpstate, link);
PREPEND(tcpstates, tcpstate, link);
return tcpstate;
}
tcpstate_ptr tcpstate_getcurr(void)
{
return _curr_tcpstate;
}
/* Discard this packet. If it's part of TCP stream, all subsequent pkts on
* the same tcp stream will also be discarded. */
void tcpstate_discard(tcpstate_ptr tcpstate, const char* msg)
{
if (dumptrace >= 3 && msg)
fprintf(stderr, "discarding packet: %s\n", msg);
if (tcpstate) {
UNLINK(tcpstates, tcpstate, link);
if (tcpstate->reasm) {
tcpreasm_free(tcpstate->reasm);
}
free(tcpstate);
if (_curr_tcpstate == tcpstate) {
_curr_tcpstate = 0;
}
tcpstate_count--;
}
}
void tcpstate_reset(tcpstate_ptr tcpstate, const char* msg)
{
if (options.allow_reset_tcpstate && tcpstate) {
if (dumptrace >= 3 && msg)
fprintf(stderr, "resetting tcpstate: %s\n", msg);
tcpstate->start = tcpstate->currseq;
tcpstate->maxdiff = 0;
tcpstate->dnslen = 0;
tcpstate->lastdns = tcpstate->currseq + tcpstate->currlen;
if (tcpstate->reasm) {
tcpreasm_reset(tcpstate->reasm);
tcpstate->reasm->seq_start = tcpstate->start;
}
}
}
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