2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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9 * notice, this list of conditions and the following disclaimer.
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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
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17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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29 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
36 #include "opt_inet6.h"
37 #include "opt_tcpdebug.h"
39 #include <sys/param.h>
40 #include <sys/kernel.h>
41 #include <sys/malloc.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>
52 #include <net/route.h>
55 #include <netinet/in.h>
56 #include <netinet/in_pcb.h>
57 #include <netinet/in_systm.h>
58 #include <netinet/in_var.h>
59 #include <netinet/ip.h>
60 #include <netinet/ip_var.h>
61 #include <netinet/ip_options.h>
62 #include <netinet/ip6.h>
63 #include <netinet6/in6_pcb.h>
64 #include <netinet6/ip6_var.h>
65 #include <netinet6/nd6.h>
66 #include <netinet/tcp.h>
67 #include <netinet/tcp_fsm.h>
68 #include <netinet/tcp_seq.h>
69 #include <netinet/tcp_timer.h>
70 #include <netinet/tcp_var.h>
71 #include <netinet6/tcp6_var.h>
72 #include <netinet/tcpip.h>
74 #include <netinet/tcp_debug.h>
77 static int tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS);
78 static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS);
80 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
81 "TCP Segment Reassembly Queue");
83 static VNET_DEFINE(int, tcp_reass_maxseg) = 0;
84 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg)
85 SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, maxsegments,
86 CTLTYPE_INT | CTLFLAG_RDTUN,
87 &VNET_NAME(tcp_reass_maxseg), 0, &tcp_reass_sysctl_maxseg, "I",
88 "Global maximum number of TCP Segments in Reassembly Queue");
90 static VNET_DEFINE(int, tcp_reass_qsize) = 0;
91 #define V_tcp_reass_qsize VNET(tcp_reass_qsize)
92 SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments,
93 CTLTYPE_INT | CTLFLAG_RD,
94 &VNET_NAME(tcp_reass_qsize), 0, &tcp_reass_sysctl_qsize, "I",
95 "Global number of TCP Segments currently in Reassembly Queue");
97 static VNET_DEFINE(int, tcp_reass_overflows) = 0;
98 #define V_tcp_reass_overflows VNET(tcp_reass_overflows)
99 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows,
100 CTLTYPE_INT | CTLFLAG_RD,
101 &VNET_NAME(tcp_reass_overflows), 0,
102 "Global number of TCP Segment Reassembly Queue Overflows");
104 static VNET_DEFINE(uma_zone_t, tcp_reass_zone);
105 #define V_tcp_reass_zone VNET(tcp_reass_zone)
107 /* Initialize TCP reassembly queue */
109 tcp_reass_zone_change(void *tag)
112 V_tcp_reass_maxseg = nmbclusters / 16;
113 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
120 V_tcp_reass_maxseg = nmbclusters / 16;
121 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
122 &V_tcp_reass_maxseg);
123 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
124 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
125 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
126 EVENTHANDLER_REGISTER(nmbclusters_change,
127 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
132 tcp_reass_destroy(void)
135 uma_zdestroy(V_tcp_reass_zone);
140 tcp_reass_flush(struct tcpcb *tp)
142 struct tseg_qent *qe;
144 INP_WLOCK_ASSERT(tp->t_inpcb);
146 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) {
147 LIST_REMOVE(qe, tqe_q);
149 uma_zfree(V_tcp_reass_zone, qe);
153 KASSERT((tp->t_segqlen == 0),
154 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
159 tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS)
161 V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone);
162 return (sysctl_handle_int(oidp, arg1, arg2, req));
166 tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS)
168 V_tcp_reass_qsize = uma_zone_get_cur(V_tcp_reass_zone);
169 return (sysctl_handle_int(oidp, arg1, arg2, req));
173 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
176 struct tseg_qent *p = NULL;
177 struct tseg_qent *nq;
178 struct tseg_qent *te = NULL;
179 struct socket *so = tp->t_inpcb->inp_socket;
182 struct tseg_qent tqs;
184 INP_WLOCK_ASSERT(tp->t_inpcb);
187 * XXX: tcp_reass() is rather inefficient with its data structures
188 * and should be rewritten (see NetBSD for optimizations).
192 * Call with th==NULL after become established to
193 * force pre-ESTABLISHED data up to user socket.
199 * Limit the number of segments that can be queued to reduce the
200 * potential for mbuf exhaustion. For best performance, we want to be
201 * able to queue a full window's worth of segments. The size of the
202 * socket receive buffer determines our advertised window and grows
203 * automatically when socket buffer autotuning is enabled. Use it as the
204 * basis for our queue limit.
205 * Always let the missing segment through which caused this queue.
206 * NB: Access to the socket buffer is left intentionally unlocked as we
207 * can tolerate stale information here.
209 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
210 * should work but causes packets to be dropped when they shouldn't.
211 * Investigate why and re-evaluate the below limit after the behaviour
214 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
215 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) {
216 V_tcp_reass_overflows++;
217 TCPSTAT_INC(tcps_rcvmemdrop);
220 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
221 log(LOG_DEBUG, "%s; %s: queue limit reached, "
222 "segment dropped\n", s, __func__);
229 * Allocate a new queue entry. If we can't, or hit the zone limit
232 * Use a temporary structure on the stack for the missing segment
233 * when the zone is exhausted. Otherwise we may get stuck.
235 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT);
237 if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) {
238 TCPSTAT_INC(tcps_rcvmemdrop);
241 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
243 log(LOG_DEBUG, "%s; %s: global zone limit "
244 "reached, segment dropped\n", s, __func__);
249 bzero(&tqs, sizeof(struct tseg_qent));
251 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
254 "%s; %s: global zone limit reached, using "
255 "stack for missing segment\n", s, __func__);
263 * Find a segment which begins after this one does.
265 LIST_FOREACH(q, &tp->t_segq, tqe_q) {
266 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
272 * If there is a preceding segment, it may provide some of
273 * our data already. If so, drop the data from the incoming
274 * segment. If it provides all of our data, drop us.
278 /* conversion to int (in i) handles seq wraparound */
279 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
282 TCPSTAT_INC(tcps_rcvduppack);
283 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
286 uma_zfree(V_tcp_reass_zone, te);
289 * Try to present any queued data
290 * at the left window edge to the user.
291 * This is needed after the 3-WHS
294 goto present; /* ??? */
302 TCPSTAT_INC(tcps_rcvoopack);
303 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
306 * While we overlap succeeding segments trim them or,
307 * if they are completely covered, dequeue them.
310 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
313 if (i < q->tqe_len) {
314 q->tqe_th->th_seq += i;
320 nq = LIST_NEXT(q, tqe_q);
321 LIST_REMOVE(q, tqe_q);
323 uma_zfree(V_tcp_reass_zone, q);
328 /* Insert the new segment queue entry into place. */
331 te->tqe_len = *tlenp;
334 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
336 KASSERT(te != &tqs, ("%s: temporary stack based entry not "
337 "first element in queue", __func__));
338 LIST_INSERT_AFTER(p, te, tqe_q);
343 * Present data to user, advancing rcv_nxt through
344 * completed sequence space.
346 if (!TCPS_HAVEESTABLISHED(tp->t_state))
348 q = LIST_FIRST(&tp->t_segq);
349 if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
351 SOCKBUF_LOCK(&so->so_rcv);
353 tp->rcv_nxt += q->tqe_len;
354 flags = q->tqe_th->th_flags & TH_FIN;
355 nq = LIST_NEXT(q, tqe_q);
356 LIST_REMOVE(q, tqe_q);
357 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
360 sbappendstream_locked(&so->so_rcv, q->tqe_m);
362 uma_zfree(V_tcp_reass_zone, q);
365 } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
367 sorwakeup_locked(so);