1 /*
2 * Copyright (c) 2018-2021, OARC, Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. Neither the name of the copyright holder nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
29 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
31 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32 * POSSIBILITY OF SUCH DAMAGE.
33 */
34
35 #include "config.h"
36
37 #include "tcpstate.h"
38 #include "iaddr.h"
39 #include "log.h"
40 #include "tcpreasm.h"
41
42 #define MAX_TCP_IDLE_TIME 600
43 #define MAX_TCP_IDLE_COUNT 4096
44 #define TCP_GC_TIME 60
45
tcpstate_find(iaddr from,iaddr to,unsigned sport,unsigned dport,time_t t)46 tcpstate_ptr tcpstate_find(iaddr from, iaddr to, unsigned sport, unsigned dport, time_t t)
47 {
48 static time_t next_gc = 0;
49 tcpstate_ptr tcpstate;
50
51 for (tcpstate = HEAD(tcpstates);
52 tcpstate != NULL;
53 tcpstate = NEXT(tcpstate, link)) {
54 if (ia_equal(tcpstate->saddr, from) && ia_equal(tcpstate->daddr, to) && tcpstate->sport == sport && tcpstate->dport == dport)
55 break;
56 }
57 if (tcpstate != NULL) {
58 tcpstate->last_use = t;
59 if (tcpstate != HEAD(tcpstates)) {
60 /* move to beginning of list */
61 UNLINK(tcpstates, tcpstate, link);
62 PREPEND(tcpstates, tcpstate, link);
63 }
64 }
65
66 if (t >= next_gc || tcpstate_count > MAX_TCP_IDLE_COUNT) {
67 /* garbage collect stale states */
68 time_t min_last_use = t - MAX_TCP_IDLE_TIME;
69 while ((tcpstate = TAIL(tcpstates)) && tcpstate->last_use < min_last_use) {
70 UNLINK(tcpstates, tcpstate, link);
71 tcpstate_count--;
72 }
73 next_gc = t + TCP_GC_TIME;
74 }
75
76 return tcpstate;
77 }
78
tcpstate_new(iaddr from,iaddr to,unsigned sport,unsigned dport)79 tcpstate_ptr tcpstate_new(iaddr from, iaddr to, unsigned sport, unsigned dport)
80 {
81
82 tcpstate_ptr tcpstate = calloc(1, sizeof *tcpstate);
83 if (tcpstate == NULL) {
84 /* Out of memory; recycle the least recently used */
85 logerr("warning: out of memory, "
86 "discarding some TCP state early");
87 tcpstate = TAIL(tcpstates);
88 assert(tcpstate != NULL);
89 } else {
90 tcpstate_count++;
91 }
92 tcpstate->saddr = from;
93 tcpstate->daddr = to;
94 tcpstate->sport = sport;
95 tcpstate->dport = dport;
96 INIT_LINK(tcpstate, link);
97 PREPEND(tcpstates, tcpstate, link);
98 return tcpstate;
99 }
100
101 /* Discard this packet. If it's part of TCP stream, all subsequent pkts on
102 * the same tcp stream will also be discarded. */
tcpstate_discard(tcpstate_ptr tcpstate,const char * msg)103 void tcpstate_discard(tcpstate_ptr tcpstate, const char* msg)
104 {
105 if (dumptrace >= 3 && msg)
106 fprintf(stderr, "discarding packet: %s\n", msg);
107 if (tcpstate) {
108 UNLINK(tcpstates, tcpstate, link);
109 if (tcpstate->reasm) {
110 tcpreasm_free(tcpstate->reasm);
111 }
112 free(tcpstate);
113 tcpstate_count--;
114 return;
115 }
116 }
117
118 tcpstate_ptr _curr_tcpstate = 0;
119
tcpstate_getcurr(void)120 tcpstate_ptr tcpstate_getcurr(void)
121 {
122 return _curr_tcpstate;
123 }
124
tcpstate_reset(tcpstate_ptr tcpstate,const char * msg)125 void tcpstate_reset(tcpstate_ptr tcpstate, const char* msg)
126 {
127 if (options.allow_reset_tcpstate && tcpstate) {
128 if (dumptrace >= 3 && msg)
129 fprintf(stderr, "resetting tcpstate: %s\n", msg);
130
131 tcpstate->start = tcpstate->currseq;
132 tcpstate->maxdiff = 0;
133 tcpstate->dnslen = 0;
134 tcpstate->lastdns = tcpstate->currseq + tcpstate->currlen;
135
136 if (tcpstate->reasm) {
137 tcpreasm_reset(tcpstate->reasm);
138 tcpstate->reasm->seq_start = tcpstate->start;
139 }
140 }
141 }
142