diff options
Diffstat (limited to 'src/tcpstate.c')
| -rw-r--r-- | src/tcpstate.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/src/tcpstate.c b/src/tcpstate.c new file mode 100644 index 0000000..bfc5198 --- /dev/null +++ b/src/tcpstate.c @@ -0,0 +1,141 @@ +/* + * Copyright (c) 2018-2021, 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; + + 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); + } + } + + if (t >= next_gc || tcpstate_count > MAX_TCP_IDLE_COUNT) { + /* garbage collect stale states */ + time_t min_last_use = t - MAX_TCP_IDLE_TIME; + while ((tcpstate = TAIL(tcpstates)) && tcpstate->last_use < min_last_use) { + UNLINK(tcpstates, tcpstate, link); + tcpstate_count--; + } + next_gc = t + TCP_GC_TIME; + } + + return tcpstate; +} + +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); + } 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; +} + +/* 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); + tcpstate_count--; + return; + } +} + +tcpstate_ptr _curr_tcpstate = 0; + +tcpstate_ptr tcpstate_getcurr(void) +{ + return _curr_tcpstate; +} + +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; + } + } +} |