1 /*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
3 * The Regents of the University of California. 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 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37 #include "opt_tcpdebug.h"
38
39 #include <sys/param.h>
40 #include <sys/kernel.h>
41 #include <sys/malloc.h>
42 #include <sys/mbuf.h>
43 #include <sys/socket.h>
44 #include <sys/socketvar.h>
45 #include <sys/sysctl.h>
46 #include <sys/syslog.h>
47 #include <sys/systm.h>
48
49 #include <vm/uma.h>
50
51 #include <net/if.h>
52 #include <net/route.h>
53
54 #include <netinet/in.h>
55 #include <netinet/in_pcb.h>
56 #include <netinet/in_systm.h>
57 #include <netinet/in_var.h>
58 #include <netinet/ip.h>
59 #include <netinet/ip_var.h>
60 #include <netinet/ip_options.h>
61 #include <netinet/ip6.h>
62 #include <netinet6/in6_pcb.h>
63 #include <netinet6/ip6_var.h>
64 #include <netinet6/nd6.h>
65 #include <netinet/tcp.h>
66 #include <netinet/tcp_fsm.h>
67 #include <netinet/tcp_seq.h>
68 #include <netinet/tcp_timer.h>
69 #include <netinet/tcp_var.h>
70 #include <netinet6/tcp6_var.h>
71 #include <netinet/tcpip.h>
72 #ifdef TCPDEBUG
73 #include <netinet/tcp_debug.h>
74 #endif /* TCPDEBUG */
75
76 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
77 "TCP Segment Reassembly Queue");
78
79 static int tcp_reass_maxseg = 0;
80 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
81 &tcp_reass_maxseg, 0,
82 "Global maximum number of TCP Segments in Reassembly Queue");
83
84 int tcp_reass_qsize = 0;
85 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
86 &tcp_reass_qsize, 0,
87 "Global number of TCP Segments currently in Reassembly Queue");
88
89 static int tcp_reass_maxqlen = 48;
90 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxqlen, CTLFLAG_RW,
91 &tcp_reass_maxqlen, 0,
92 "Maximum number of TCP Segments per individual Reassembly Queue");
93
94 static int tcp_reass_overflows = 0;
95 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
96 &tcp_reass_overflows, 0,
97 "Global number of TCP Segment Reassembly Queue Overflows");
98
99 /* Initialize TCP reassembly queue */
100 static void
101 tcp_reass_zone_change(void *tag)
102 {
103
104 tcp_reass_maxseg = nmbclusters / 16;
105 uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg);
106 }
107
108 uma_zone_t tcp_reass_zone;
109
110 void
111 tcp_reass_init(void)
112 {
113
114 tcp_reass_maxseg = nmbclusters / 16;
115 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
116 &tcp_reass_maxseg);
117 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
118 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
119 uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg);
120 EVENTHANDLER_REGISTER(nmbclusters_change,
121 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
122 }
123
124 int
125 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
126 {
127 struct tseg_qent *q;
128 struct tseg_qent *p = NULL;
129 struct tseg_qent *nq;
130 struct tseg_qent *te = NULL;
131 struct socket *so = tp->t_inpcb->inp_socket;
132 int flags;
133
134 INP_LOCK_ASSERT(tp->t_inpcb);
135
136 /*
137 * XXX: tcp_reass() is rather inefficient with its data structures
138 * and should be rewritten (see NetBSD for optimizations). While
139 * doing that it should move to its own file tcp_reass.c.
140 */
141
142 /*
143 * Call with th==NULL after become established to
144 * force pre-ESTABLISHED data up to user socket.
145 */
146 if (th == NULL)
147 goto present;
148
149 /*
150 * Limit the number of segments in the reassembly queue to prevent
151 * holding on to too many segments (and thus running out of mbufs).
152 * Make sure to let the missing segment through which caused this
153 * queue. Always keep one global queue entry spare to be able to
154 * process the missing segment.
155 */
156 if (th->th_seq != tp->rcv_nxt &&
157 (tcp_reass_qsize + 1 >= tcp_reass_maxseg ||
158 tp->t_segqlen >= tcp_reass_maxqlen)) {
159 tcp_reass_overflows++;
160 tcpstat.tcps_rcvmemdrop++;
161 m_freem(m);
162 *tlenp = 0;
163 return (0);
164 }
165
166 /*
167 * Allocate a new queue entry. If we can't, or hit the zone limit
168 * just drop the pkt.
169 */
170 te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
171 if (te == NULL) {
172 tcpstat.tcps_rcvmemdrop++;
173 m_freem(m);
174 *tlenp = 0;
175 return (0);
176 }
177 tp->t_segqlen++;
178 tcp_reass_qsize++;
179
180 /*
181 * Find a segment which begins after this one does.
182 */
183 LIST_FOREACH(q, &tp->t_segq, tqe_q) {
184 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
185 break;
186 p = q;
187 }
188
189 /*
190 * If there is a preceding segment, it may provide some of
191 * our data already. If so, drop the data from the incoming
192 * segment. If it provides all of our data, drop us.
193 */
194 if (p != NULL) {
195 int i;
196 /* conversion to int (in i) handles seq wraparound */
197 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
198 if (i > 0) {
199 if (i >= *tlenp) {
200 tcpstat.tcps_rcvduppack++;
201 tcpstat.tcps_rcvdupbyte += *tlenp;
202 m_freem(m);
203 uma_zfree(tcp_reass_zone, te);
204 tp->t_segqlen--;
205 tcp_reass_qsize--;
206 /*
207 * Try to present any queued data
208 * at the left window edge to the user.
209 * This is needed after the 3-WHS
210 * completes.
211 */
212 goto present; /* ??? */
213 }
214 m_adj(m, i);
215 *tlenp -= i;
216 th->th_seq += i;
217 }
218 }
219 tcpstat.tcps_rcvoopack++;
220 tcpstat.tcps_rcvoobyte += *tlenp;
221
222 /*
223 * While we overlap succeeding segments trim them or,
224 * if they are completely covered, dequeue them.
225 */
226 while (q) {
227 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
228 if (i <= 0)
229 break;
230 if (i < q->tqe_len) {
231 q->tqe_th->th_seq += i;
232 q->tqe_len -= i;
233 m_adj(q->tqe_m, i);
234 break;
235 }
236
237 nq = LIST_NEXT(q, tqe_q);
238 LIST_REMOVE(q, tqe_q);
239 m_freem(q->tqe_m);
240 uma_zfree(tcp_reass_zone, q);
241 tp->t_segqlen--;
242 tcp_reass_qsize--;
243 q = nq;
244 }
245
246 /* Insert the new segment queue entry into place. */
247 te->tqe_m = m;
248 te->tqe_th = th;
249 te->tqe_len = *tlenp;
250
251 if (p == NULL) {
252 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
253 } else {
254 LIST_INSERT_AFTER(p, te, tqe_q);
255 }
256
257 present:
258 /*
259 * Present data to user, advancing rcv_nxt through
260 * completed sequence space.
261 */
262 if (!TCPS_HAVEESTABLISHED(tp->t_state))
263 return (0);
264 q = LIST_FIRST(&tp->t_segq);
265 if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
266 return (0);
267 SOCKBUF_LOCK(&so->so_rcv);
268 do {
269 tp->rcv_nxt += q->tqe_len;
270 flags = q->tqe_th->th_flags & TH_FIN;
271 nq = LIST_NEXT(q, tqe_q);
272 LIST_REMOVE(q, tqe_q);
273 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
274 m_freem(q->tqe_m);
275 else
276 sbappendstream_locked(&so->so_rcv, q->tqe_m);
277 uma_zfree(tcp_reass_zone, q);
278 tp->t_segqlen--;
279 tcp_reass_qsize--;
280 q = nq;
281 } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
282 ND6_HINT(tp);
283 sorwakeup_locked(so);
284 return (flags);
285 }
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