2 * SPDX-License-Identifier: BSD-3-Clause
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5 * The Regents of the University of California. All rights reserved.
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31 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
38 #include "opt_inet6.h"
39 #include "opt_tcpdebug.h"
41 /* For debugging we want counters and BB logging */
42 /* #define TCP_REASS_COUNTERS 1 */
43 /* #define TCP_REASS_LOGGING 1 */
45 #include <sys/param.h>
46 #include <sys/kernel.h>
47 #include <sys/eventhandler.h>
48 #include <sys/malloc.h>
50 #include <sys/socket.h>
51 #include <sys/socketvar.h>
52 #include <sys/sysctl.h>
53 #include <sys/syslog.h>
54 #include <sys/systm.h>
59 #include <net/if_var.h>
60 #include <net/route.h>
63 #include <netinet/in.h>
64 #include <netinet/in_pcb.h>
65 #include <netinet/in_systm.h>
66 #include <netinet/in_var.h>
67 #include <netinet/ip.h>
68 #include <netinet/ip_var.h>
69 #include <netinet/ip_options.h>
70 #include <netinet/ip6.h>
71 #include <netinet6/in6_pcb.h>
72 #include <netinet6/ip6_var.h>
73 #include <netinet6/nd6.h>
74 #include <netinet/tcp.h>
75 #include <netinet/tcp_fsm.h>
76 #include <netinet/tcp_seq.h>
77 #include <netinet/tcp_timer.h>
78 #include <netinet/tcp_var.h>
79 #ifdef TCP_REASS_LOGGING
80 #include <netinet/tcp_log_buf.h>
81 #include <netinet/tcp_hpts.h>
83 #include <netinet/tcpip.h>
85 #include <netinet/tcp_debug.h>
88 #define TCP_R_LOG_ADD 1
89 #define TCP_R_LOG_LIMIT_REACHED 2
90 #define TCP_R_LOG_APPEND 3
91 #define TCP_R_LOG_PREPEND 4
92 #define TCP_R_LOG_REPLACE 5
93 #define TCP_R_LOG_MERGE_INTO 6
94 #define TCP_R_LOG_NEW_ENTRY 7
95 #define TCP_R_LOG_READ 8
96 #define TCP_R_LOG_ZERO 9
97 #define TCP_R_LOG_DUMP 10
98 #define TCP_R_LOG_TRIM 11
100 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass,
101 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
102 "TCP Segment Reassembly Queue");
104 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats,
105 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
106 "TCP Segment Reassembly stats");
108 static int tcp_reass_maxseg = 0;
109 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
110 &tcp_reass_maxseg, 0,
111 "Global maximum number of TCP Segments in Reassembly Queue");
113 static uma_zone_t tcp_reass_zone;
114 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
116 "Global number of TCP Segments currently in Reassembly Queue");
118 static u_int tcp_reass_maxqueuelen = 100;
119 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
120 &tcp_reass_maxqueuelen, 0,
121 "Maximum number of TCP Segments per Reassembly Queue");
123 static int tcp_new_limits = 0;
124 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN,
126 "Do we use the new limit method we are discussing?");
128 static u_int tcp_reass_queue_guard = 16;
129 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN,
130 &tcp_reass_queue_guard, 16,
131 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode");
133 #ifdef TCP_REASS_COUNTERS
135 counter_u64_t reass_entry;
136 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD,
137 &reass_entry, "A segment entered reassembly ");
139 counter_u64_t reass_path1;
140 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD,
141 &reass_path1, "Took path 1");
143 counter_u64_t reass_path2;
144 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD,
145 &reass_path2, "Took path 2");
147 counter_u64_t reass_path3;
148 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD,
149 &reass_path3, "Took path 3");
151 counter_u64_t reass_path4;
152 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD,
153 &reass_path4, "Took path 4");
155 counter_u64_t reass_path5;
156 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD,
157 &reass_path5, "Took path 5");
159 counter_u64_t reass_path6;
160 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD,
161 &reass_path6, "Took path 6");
163 counter_u64_t reass_path7;
164 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD,
165 &reass_path7, "Took path 7");
167 counter_u64_t reass_fullwalk;
168 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD,
169 &reass_fullwalk, "Took a full walk ");
171 counter_u64_t reass_nospace;
172 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD,
173 &reass_nospace, "Had no mbuf capacity ");
175 counter_u64_t merge_fwd;
176 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD,
177 &merge_fwd, "Ran merge fwd");
179 counter_u64_t merge_into;
180 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD,
181 &merge_into, "Ran merge into");
183 counter_u64_t tcp_zero_input;
184 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD,
185 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc");
189 /* Initialize TCP reassembly queue */
191 tcp_reass_zone_change(void *tag)
194 /* Set the zone limit and read back the effective value. */
195 tcp_reass_maxseg = nmbclusters / 16;
196 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
200 #ifdef TCP_REASS_LOGGING
203 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p,
204 tcp_seq seq, int len, uint8_t action, int instance)
209 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
210 union tcp_log_stackspecific log;
212 memset(&log, 0, sizeof(log));
213 cts = tcp_get_usecs(&tv);
214 log.u_bbr.flex1 = seq;
215 log.u_bbr.cur_del_rate = (uint64_t)q;
216 log.u_bbr.delRate = (uint64_t)p;
218 log.u_bbr.flex2 = q->tqe_start;
219 log.u_bbr.flex3 = q->tqe_len;
220 log.u_bbr.flex4 = q->tqe_mbuf_cnt;
221 log.u_bbr.hptsi_gain = q->tqe_flags;
224 log.u_bbr.flex5 = p->tqe_start;
225 log.u_bbr.pkts_out = p->tqe_len;
226 log.u_bbr.epoch = p->tqe_mbuf_cnt;
227 log.u_bbr.cwnd_gain = p->tqe_flags;
229 log.u_bbr.flex6 = tp->t_segqmbuflen;
230 log.u_bbr.flex7 = instance;
231 log.u_bbr.flex8 = action;
232 log.u_bbr.timeStamp = cts;
233 TCP_LOG_EVENTP(tp, NULL,
234 &tp->t_inpcb->inp_socket->so_rcv,
235 &tp->t_inpcb->inp_socket->so_snd,
237 len, &log, false, &tv);
242 tcp_reass_log_dump(struct tcpcb *tp)
246 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
247 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
248 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0);
254 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m,
255 int logval, struct tseg_qent *q)
266 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt);
272 tcp_reass_global_init(void)
275 tcp_reass_maxseg = nmbclusters / 16;
276 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
278 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
279 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
280 /* Set the zone limit and read back the effective value. */
281 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
283 #ifdef TCP_REASS_COUNTERS
284 reass_path1 = counter_u64_alloc(M_WAITOK);
285 reass_path2 = counter_u64_alloc(M_WAITOK);
286 reass_path3 = counter_u64_alloc(M_WAITOK);
287 reass_path4 = counter_u64_alloc(M_WAITOK);
288 reass_path5 = counter_u64_alloc(M_WAITOK);
289 reass_path6 = counter_u64_alloc(M_WAITOK);
290 reass_path7 = counter_u64_alloc(M_WAITOK);
291 reass_fullwalk = counter_u64_alloc(M_WAITOK);
292 reass_nospace = counter_u64_alloc(M_WAITOK);
293 reass_entry = counter_u64_alloc(M_WAITOK);
294 merge_fwd = counter_u64_alloc(M_WAITOK);
295 merge_into = counter_u64_alloc(M_WAITOK);
296 tcp_zero_input = counter_u64_alloc(M_WAITOK);
298 EVENTHANDLER_REGISTER(nmbclusters_change,
299 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
304 tcp_reass_flush(struct tcpcb *tp)
306 struct tseg_qent *qe;
308 INP_WLOCK_ASSERT(tp->t_inpcb);
310 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) {
311 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q);
313 uma_zfree(tcp_reass_zone, qe);
316 tp->t_segqmbuflen = 0;
317 KASSERT((tp->t_segqlen == 0),
318 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
323 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last,
324 struct mbuf *m, struct tcphdr *th, int tlen,
325 struct mbuf *mlast, int lenofoh)
328 #ifdef TCP_REASS_LOGGING
329 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0);
331 last->tqe_len += tlen;
332 last->tqe_m->m_pkthdr.len += tlen;
333 /* Preserve the FIN bit if its there */
334 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN);
335 last->tqe_last->m_next = m;
336 last->tqe_last = mlast;
337 last->tqe_mbuf_cnt += lenofoh;
339 TCPSTAT_INC(tcps_rcvoopack);
340 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
341 #ifdef TCP_REASS_LOGGING
342 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m,
349 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th,
350 int tlen, struct mbuf *mlast, int lenofoh)
354 #ifdef TCP_REASS_LOGGING
355 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0);
357 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) {
358 /* The new data overlaps into the old */
359 i = (th->th_seq + tlen) - first->tqe_start;
360 #ifdef TCP_REASS_LOGGING
361 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1);
363 m_adj(first->tqe_m, i);
365 first->tqe_start += i;
367 /* Ok now setup our chain to point to the old first */
368 mlast->m_next = first->tqe_m;
370 first->tqe_len += tlen;
371 first->tqe_start = th->th_seq;
372 first->tqe_m->m_pkthdr.len = first->tqe_len;
373 first->tqe_mbuf_cnt += lenofoh;
375 TCPSTAT_INC(tcps_rcvoopack);
376 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
377 #ifdef TCP_REASS_LOGGING
378 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m,
385 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m,
386 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags)
389 * Free the data in q, and replace
390 * it with the new segment.
394 #ifdef TCP_REASS_LOGGING
395 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0);
398 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
399 ("Tp:%p seg queue goes negative", tp));
400 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
401 q->tqe_mbuf_cnt = mbufoh;
405 if (len > q->tqe_len)
406 len_dif = len - q->tqe_len;
410 TCPSTAT_INC(tcps_rcvoopack);
411 TCPSTAT_ADD(tcps_rcvoobyte, len_dif);
413 q->tqe_flags = (flags & TH_FIN);
414 q->tqe_m->m_pkthdr.len = q->tqe_len;
415 tp->t_segqmbuflen += mbufoh;
420 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent,
424 * Merge q into ent and free q from the list.
426 #ifdef TCP_REASS_LOGGING
427 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0);
429 #ifdef TCP_REASS_COUNTERS
430 counter_u64_add(merge_into, 1);
432 ent->tqe_last->m_next = q->tqe_m;
433 ent->tqe_last = q->tqe_last;
434 ent->tqe_len += q->tqe_len;
435 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt;
436 ent->tqe_m->m_pkthdr.len += q->tqe_len;
437 ent->tqe_flags |= (q->tqe_flags & TH_FIN);
438 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
439 uma_zfree(tcp_reass_zone, q);
445 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent)
447 struct tseg_qent *q, *qtmp;
451 * Given an entry merge forward anyplace
452 * that ent overlaps forward.
455 max = ent->tqe_start + ent->tqe_len;
456 q = TAILQ_NEXT(ent, tqe_q);
461 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) {
462 if (SEQ_GT(q->tqe_start, max)) {
466 /* We have some or all that are overlapping */
467 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) {
468 /* It consumes it all */
469 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
471 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
472 uma_zfree(tcp_reass_zone, q);
477 * Trim the q entry to dovetail to this one
478 * and then merge q into ent updating max
481 i = max - q->tqe_start;
482 #ifdef TCP_REASS_LOGGING
483 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2);
488 tcp_reass_merge_into(tp, ent, q);
489 max = ent->tqe_start + ent->tqe_len;
491 #ifdef TCP_REASS_COUNTERS
492 counter_u64_add(merge_fwd, 1);
497 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast)
501 if (m->m_flags & M_EXT)
502 len += m->m_ext.ext_size;
503 while (m->m_next != NULL) {
506 if (m->m_flags & M_EXT)
507 len += m->m_ext.ext_size;
514 * NOTE!!! the new tcp-reassembly code *must not* use
515 * m_adj() with a negative index. That alters the chain
516 * of mbufs (by possibly chopping trailing mbufs). At
517 * the front of tcp_reass we count the mbuf overhead
518 * and setup the tail pointer. If we use m_adj(m, -5)
519 * we could corrupt the tail pointer. Currently the
520 * code only uses m_adj(m, postive-num). If this
521 * changes appropriate changes to update mlast would
525 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start,
526 int *tlenp, struct mbuf *m)
528 struct tseg_qent *q, *last, *first;
529 struct tseg_qent *p = NULL;
530 struct tseg_qent *nq = NULL;
531 struct tseg_qent *te = NULL;
532 struct mbuf *mlast = NULL;
534 struct socket *so = tp->t_inpcb->inp_socket;
536 int flags, i, lenofoh;
538 INP_WLOCK_ASSERT(tp->t_inpcb);
540 * XXX: tcp_reass() is rather inefficient with its data structures
541 * and should be rewritten (see NetBSD for optimizations).
544 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL),
545 ("tcp_reass called with illegal parameter combination "
546 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)",
547 tp, th, seq_start, tlenp, m));
549 * Call with th==NULL after become established to
550 * force pre-ESTABLISHED data up to user socket.
554 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt),
555 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)",
557 #ifdef TCP_REASS_LOGGING
558 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL);
560 #ifdef TCP_REASS_COUNTERS
561 counter_u64_add(reass_entry, 1);
564 * Check for zero length data.
566 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) {
568 * A zero length segment does no
569 * one any good. We could check
570 * the rcv_nxt <-> rcv_wnd but thats
571 * already done for us by the caller.
574 #ifdef TCP_REASS_COUNTERS
575 counter_u64_add(tcp_zero_input, 1);
578 #ifdef TCP_REASS_LOGGING
579 tcp_reass_log_dump(tp);
582 } else if ((*tlenp == 0) &&
583 (tcp_get_flags(th) & TH_FIN) &&
584 !TCPS_HAVEESTABLISHED(tp->t_state)) {
586 * We have not established, and we
587 * have a FIN and no data. Lets treat
588 * this as the same as if the FIN were
589 * not present. We don't want to save
590 * the FIN bit in a reassembly buffer
591 * we want to get established first before
592 * we do that (the peer will retransmit).
599 lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
600 sb = &tp->t_inpcb->inp_socket->so_rcv;
601 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
602 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) {
604 TCPSTAT_INC(tcps_rcvreassfull);
605 #ifdef TCP_REASS_COUNTERS
606 counter_u64_add(reass_nospace, 1);
608 #ifdef TCP_REASS_LOGGING
609 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0);
611 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
612 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, "
613 "segment dropped\n", s, __func__);
618 #ifdef TCP_REASS_LOGGING
619 tcp_reass_log_dump(tp);
624 * First lets deal with two common cases, the
625 * segment appends to the back of our collected
626 * segments. Or the segment is the next in line.
628 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q);
630 if ((tcp_get_flags(th) & TH_FIN) &&
631 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) {
633 * Someone is trying to game us, dump
640 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) &&
641 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) {
642 /* Common case, trailing segment is added */
646 * reassembly buffer |---| |---| |---|
649 #ifdef TCP_REASS_COUNTERS
650 counter_u64_add(reass_path1, 1);
652 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) {
653 i = (last->tqe_start + last->tqe_len) - th->th_seq;
655 #ifdef TCP_REASS_LOGGING
656 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3);
662 /* Complete overlap */
663 TCPSTAT_INC(tcps_rcvduppack);
664 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
666 *tlenp = last->tqe_len;
667 *seq_start = last->tqe_start;
671 if (last->tqe_flags & TH_FIN) {
673 * We have data after the FIN on the last?
679 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh);
680 tp->t_segqmbuflen += lenofoh;
681 *seq_start = last->tqe_start;
682 *tlenp = last->tqe_len;
684 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) {
686 * Second common case, we missed
687 * another one and have something more
693 * reassembly buffer |---| |---| |---|
696 if (last->tqe_flags & TH_FIN) {
698 * We have data after the FIN on the last?
704 #ifdef TCP_REASS_COUNTERS
705 counter_u64_add(reass_path2, 1);
711 /* First segment (it's NULL). */
714 first = TAILQ_FIRST(&tp->t_segq);
715 if (SEQ_LT(th->th_seq, first->tqe_start) &&
716 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) &&
717 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) {
719 * The head of the queue is prepended by this and
720 * it may be the one I want most.
725 * rea: |---| |---| |---|
727 * Note the case we do not deal with here is:
728 * rea= |---| |---| |---|
730 * Due to the fact that it could be
731 * new |--------------------|
732 * And we might need to merge forward.
735 struct mbuf *firstmbuf;
738 #ifdef TCP_REASS_COUNTERS
739 counter_u64_add(reass_path3, 1);
741 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) {
743 * The resend was even before
744 * what we have. We need to trim it.
745 * Note TSNH (it should be trimmed
746 * before the call to tcp_reass()).
749 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed",
750 th->th_seq, tp->rcv_nxt, tp);
752 i = tp->rcv_nxt - th->th_seq;
753 #ifdef TCP_REASS_LOGGING
754 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4);
762 firstmbuf = first->tqe_m;
764 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh);
766 if (firstmbuf == first->tqe_m) {
767 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
768 m, firstmbuf, first->tqe_m, tp, first);
769 } else if (first->tqe_m != m) {
770 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
771 m, firstmbuf, first->tqe_m, tp, first);
774 tp->t_segqmbuflen += lenofoh;
775 *seq_start = first->tqe_start;
776 *tlenp = first->tqe_len;
778 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) {
779 /* New segment is before our earliest segment. */
790 * Find a segment which begins after this one does.
792 #ifdef TCP_REASS_COUNTERS
793 counter_u64_add(reass_fullwalk, 1);
795 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
796 if (SEQ_GT(q->tqe_start, th->th_seq))
799 p = TAILQ_PREV(q, tsegqe_head, tqe_q);
801 * Now is this fit just in-between only?
805 * res= |--| |--| |--|
808 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) &&
809 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) {
814 * If we reach here we have some (possibly all) overlap
816 * res= |--| |--| |--|
818 * or new= |-----------------|
821 * or new= |-----------|
824 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) {
825 /* conversion to int (in i) handles seq wraparound */
827 #ifdef TCP_REASS_COUNTERS
828 counter_u64_add(reass_path4, 1);
830 i = p->tqe_start + p->tqe_len - th->th_seq;
836 * reassembly buffer |---|
839 TCPSTAT_INC(tcps_rcvduppack);
840 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
842 *seq_start = p->tqe_start;
845 * Try to present any queued data
846 * at the left window edge to the user.
847 * This is needed after the 3-WHS
848 * completes. Note this probably
849 * will not work and we will return.
857 * reassembly buffer |---|
858 * new segment |-----|
860 #ifdef TCP_REASS_COUNTERS
861 counter_u64_add(reass_path5, 1);
863 #ifdef TCP_REASS_LOGGING
864 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5);
871 if (th->th_seq == (p->tqe_start + p->tqe_len)) {
873 * If dovetails in with this one
879 * reassembly buffer |--| |---|
881 * (note: it was trimmed above if it overlapped)
883 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh);
884 tp->t_segqmbuflen += lenofoh;
887 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p",
888 th->th_seq, p->tqe_start, p->tqe_len,
898 * The new data runs over the
899 * top of previously sack'd data (in q).
900 * It may be partially overlapping, or
901 * it may overlap the entire segment.
903 #ifdef TCP_REASS_COUNTERS
904 counter_u64_add(reass_path6, 1);
906 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) {
907 /* It consumes it all */
911 * reassembly buffer |--| |---|
912 * new segment |----------|
914 #ifdef TCP_REASS_COUNTERS
915 counter_u64_add(reass_path7, 1);
917 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th));
920 * We just need to prepend the data
921 * to this. It does not overrun
927 * reassembly buffer |--| |---|
928 * new segment |----------|
930 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh);
931 tp->t_segqmbuflen += lenofoh;
934 /* Now does it go further than that? */
935 tcp_reass_merge_forward(tp, q);
936 *seq_start = q->tqe_start;
941 * When we reach here we can't combine it
942 * with any existing segment.
944 * Limit the number of segments that can be queued to reduce the
945 * potential for mbuf exhaustion. For best performance, we want to be
946 * able to queue a full window's worth of segments. The size of the
947 * socket receive buffer determines our advertised window and grows
948 * automatically when socket buffer autotuning is enabled. Use it as the
949 * basis for our queue limit.
951 * However, allow the user to specify a ceiling for the number of
952 * segments in each queue.
954 * Always let the missing segment through which caused this queue.
955 * NB: Access to the socket buffer is left intentionally unlocked as we
956 * can tolerate stale information here.
958 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
959 * should work but causes packets to be dropped when they shouldn't.
960 * Investigate why and re-evaluate the below limit after the behaviour
964 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) {
965 tp->rcv_nxt += *tlenp;
966 flags = tcp_get_flags(th) & TH_FIN;
967 TCPSTAT_INC(tcps_rcvoopack);
968 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
969 SOCKBUF_LOCK(&so->so_rcv);
970 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
973 sbappendstream_locked(&so->so_rcv, m, 0);
975 tp->t_flags |= TF_WAKESOR;
978 if (tcp_new_limits) {
979 if ((tp->t_segqlen > tcp_reass_queue_guard) &&
982 * This is really a lie, we are not full but
983 * are getting a segment that is above
984 * guard threshold. If it is and its below
985 * a mbuf size (256) we drop it if it
986 * can't fill in some place.
988 TCPSTAT_INC(tcps_rcvreassfull);
990 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
991 log(LOG_DEBUG, "%s; %s: queue limit reached, "
992 "segment dropped\n", s, __func__);
996 #ifdef TCP_REASS_LOGGING
997 tcp_reass_log_dump(tp);
1002 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
1003 tcp_reass_maxqueuelen)) {
1004 TCPSTAT_INC(tcps_rcvreassfull);
1006 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
1007 log(LOG_DEBUG, "%s; %s: queue limit reached, "
1008 "segment dropped\n", s, __func__);
1012 #ifdef TCP_REASS_LOGGING
1013 tcp_reass_log_dump(tp);
1019 * Allocate a new queue entry. If we can't, or hit the zone limit
1020 * just drop the pkt.
1022 te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
1024 TCPSTAT_INC(tcps_rcvmemdrop);
1027 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
1029 log(LOG_DEBUG, "%s; %s: global zone limit "
1030 "reached, segment dropped\n", s, __func__);
1037 TCPSTAT_INC(tcps_rcvoopack);
1038 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
1039 /* Insert the new segment queue entry into place. */
1041 te->tqe_flags = tcp_get_flags(th);
1042 te->tqe_len = *tlenp;
1043 te->tqe_start = th->th_seq;
1044 te->tqe_last = mlast;
1045 te->tqe_mbuf_cnt = lenofoh;
1046 tp->t_segqmbuflen += te->tqe_mbuf_cnt;
1048 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
1050 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
1052 #ifdef TCP_REASS_LOGGING
1053 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te);
1057 * Present data to user, advancing rcv_nxt through
1058 * completed sequence space.
1060 if (!TCPS_HAVEESTABLISHED(tp->t_state))
1062 q = TAILQ_FIRST(&tp->t_segq);
1063 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt),
1064 ("Reassembly queue for %p has stale entry at head", tp));
1065 if (!q || q->tqe_start != tp->rcv_nxt) {
1066 #ifdef TCP_REASS_LOGGING
1067 tcp_reass_log_dump(tp);
1071 SOCKBUF_LOCK(&so->so_rcv);
1073 tp->rcv_nxt += q->tqe_len;
1074 flags = q->tqe_flags & TH_FIN;
1075 nq = TAILQ_NEXT(q, tqe_q);
1076 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
1077 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
1080 #ifdef TCP_REASS_LOGGING
1081 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q);
1083 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1);
1085 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1);
1088 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
1090 #ifdef TCP_REASS_LOGGING
1092 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2);
1094 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2);
1097 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
1098 ("tp:%p seg queue goes negative", tp));
1099 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
1100 uma_zfree(tcp_reass_zone, q);
1103 } while (q && q->tqe_start == tp->rcv_nxt);
1104 if (TAILQ_EMPTY(&tp->t_segq) &&
1105 (tp->t_segqmbuflen != 0)) {
1107 panic("tp:%p segq:%p len:%d queue empty",
1108 tp, &tp->t_segq, tp->t_segqmbuflen);
1110 #ifdef TCP_REASS_LOGGING
1112 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0);
1114 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0);
1117 tp->t_segqmbuflen = 0;
1120 #ifdef TCP_REASS_LOGGING
1121 tcp_reass_log_dump(tp);
1123 tp->t_flags |= TF_WAKESOR;