2 * SPDX-License-Identifier: BSD-3-Clause
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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 <netinet6/tcp6_var.h>
84 #include <netinet/tcpip.h>
86 #include <netinet/tcp_debug.h>
89 #define TCP_R_LOG_ADD 1
90 #define TCP_R_LOG_LIMIT_REACHED 2
91 #define TCP_R_LOG_APPEND 3
92 #define TCP_R_LOG_PREPEND 4
93 #define TCP_R_LOG_REPLACE 5
94 #define TCP_R_LOG_MERGE_INTO 6
95 #define TCP_R_LOG_NEW_ENTRY 7
96 #define TCP_R_LOG_READ 8
97 #define TCP_R_LOG_ZERO 9
98 #define TCP_R_LOG_DUMP 10
99 #define TCP_R_LOG_TRIM 11
101 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass,
102 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
103 "TCP Segment Reassembly Queue");
105 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats,
106 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
107 "TCP Segment Reassembly stats");
110 static int tcp_reass_maxseg = 0;
111 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
112 &tcp_reass_maxseg, 0,
113 "Global maximum number of TCP Segments in Reassembly Queue");
115 static uma_zone_t tcp_reass_zone;
116 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
118 "Global number of TCP Segments currently in Reassembly Queue");
120 static u_int tcp_reass_maxqueuelen = 100;
121 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
122 &tcp_reass_maxqueuelen, 0,
123 "Maximum number of TCP Segments per Reassembly Queue");
125 static int tcp_new_limits = 0;
126 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN,
128 "Do we use the new limit method we are discussing?");
130 static u_int tcp_reass_queue_guard = 16;
131 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN,
132 &tcp_reass_queue_guard, 16,
133 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode");
135 #ifdef TCP_REASS_COUNTERS
137 counter_u64_t reass_entry;
138 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD,
139 &reass_entry, "A segment entered reassembly ");
141 counter_u64_t reass_path1;
142 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD,
143 &reass_path1, "Took path 1");
145 counter_u64_t reass_path2;
146 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD,
147 &reass_path2, "Took path 2");
149 counter_u64_t reass_path3;
150 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD,
151 &reass_path3, "Took path 3");
153 counter_u64_t reass_path4;
154 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD,
155 &reass_path4, "Took path 4");
157 counter_u64_t reass_path5;
158 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD,
159 &reass_path5, "Took path 5");
161 counter_u64_t reass_path6;
162 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD,
163 &reass_path6, "Took path 6");
165 counter_u64_t reass_path7;
166 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD,
167 &reass_path7, "Took path 7");
169 counter_u64_t reass_fullwalk;
170 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD,
171 &reass_fullwalk, "Took a full walk ");
173 counter_u64_t reass_nospace;
174 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD,
175 &reass_nospace, "Had no mbuf capacity ");
177 counter_u64_t merge_fwd;
178 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD,
179 &merge_fwd, "Ran merge fwd");
181 counter_u64_t merge_into;
182 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD,
183 &merge_into, "Ran merge into");
185 counter_u64_t tcp_zero_input;
186 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD,
187 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc");
191 /* Initialize TCP reassembly queue */
193 tcp_reass_zone_change(void *tag)
196 /* Set the zone limit and read back the effective value. */
197 tcp_reass_maxseg = nmbclusters / 16;
198 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
202 #ifdef TCP_REASS_LOGGING
205 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p,
206 tcp_seq seq, int len, uint8_t action, int instance)
211 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
212 union tcp_log_stackspecific log;
214 memset(&log, 0, sizeof(log));
215 cts = tcp_get_usecs(&tv);
216 log.u_bbr.flex1 = seq;
217 log.u_bbr.cur_del_rate = (uint64_t)q;
218 log.u_bbr.delRate = (uint64_t)p;
220 log.u_bbr.flex2 = q->tqe_start;
221 log.u_bbr.flex3 = q->tqe_len;
222 log.u_bbr.flex4 = q->tqe_mbuf_cnt;
223 log.u_bbr.hptsi_gain = q->tqe_flags;
226 log.u_bbr.flex5 = p->tqe_start;
227 log.u_bbr.pkts_out = p->tqe_len;
228 log.u_bbr.epoch = p->tqe_mbuf_cnt;
229 log.u_bbr.cwnd_gain = p->tqe_flags;
231 log.u_bbr.flex6 = tp->t_segqmbuflen;
232 log.u_bbr.flex7 = instance;
233 log.u_bbr.flex8 = action;
234 log.u_bbr.timeStamp = cts;
235 TCP_LOG_EVENTP(tp, NULL,
236 &tp->t_inpcb->inp_socket->so_rcv,
237 &tp->t_inpcb->inp_socket->so_snd,
239 len, &log, false, &tv);
244 tcp_reass_log_dump(struct tcpcb *tp)
248 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
249 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
250 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0);
256 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m,
257 int logval, struct tseg_qent *q)
268 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt);
274 tcp_reass_global_init(void)
277 tcp_reass_maxseg = nmbclusters / 16;
278 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
280 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
281 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
282 /* Set the zone limit and read back the effective value. */
283 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
285 #ifdef TCP_REASS_COUNTERS
286 reass_path1 = counter_u64_alloc(M_WAITOK);
287 reass_path2 = counter_u64_alloc(M_WAITOK);
288 reass_path3 = counter_u64_alloc(M_WAITOK);
289 reass_path4 = counter_u64_alloc(M_WAITOK);
290 reass_path5 = counter_u64_alloc(M_WAITOK);
291 reass_path6 = counter_u64_alloc(M_WAITOK);
292 reass_path7 = counter_u64_alloc(M_WAITOK);
293 reass_fullwalk = counter_u64_alloc(M_WAITOK);
294 reass_nospace = counter_u64_alloc(M_WAITOK);
295 reass_entry = counter_u64_alloc(M_WAITOK);
296 merge_fwd = counter_u64_alloc(M_WAITOK);
297 merge_into = counter_u64_alloc(M_WAITOK);
298 tcp_zero_input = counter_u64_alloc(M_WAITOK);
300 EVENTHANDLER_REGISTER(nmbclusters_change,
301 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
306 tcp_reass_flush(struct tcpcb *tp)
308 struct tseg_qent *qe;
310 INP_WLOCK_ASSERT(tp->t_inpcb);
312 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) {
313 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q);
315 uma_zfree(tcp_reass_zone, qe);
318 tp->t_segqmbuflen = 0;
319 KASSERT((tp->t_segqlen == 0),
320 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
325 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last,
326 struct mbuf *m, struct tcphdr *th, int tlen,
327 struct mbuf *mlast, int lenofoh)
330 #ifdef TCP_REASS_LOGGING
331 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0);
333 last->tqe_len += tlen;
334 last->tqe_m->m_pkthdr.len += tlen;
335 /* Preserve the FIN bit if its there */
336 last->tqe_flags |= (th->th_flags & TH_FIN);
337 last->tqe_last->m_next = m;
338 last->tqe_last = mlast;
339 last->tqe_mbuf_cnt += lenofoh;
341 TCPSTAT_INC(tcps_rcvoopack);
342 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
343 #ifdef TCP_REASS_LOGGING
344 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m,
351 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th,
352 int tlen, struct mbuf *mlast, int lenofoh)
356 #ifdef TCP_REASS_LOGGING
357 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0);
359 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) {
360 /* The new data overlaps into the old */
361 i = (th->th_seq + tlen) - first->tqe_start;
362 #ifdef TCP_REASS_LOGGING
363 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1);
365 m_adj(first->tqe_m, i);
367 first->tqe_start += i;
369 /* Ok now setup our chain to point to the old first */
370 mlast->m_next = first->tqe_m;
372 first->tqe_len += tlen;
373 first->tqe_start = th->th_seq;
374 first->tqe_m->m_pkthdr.len = first->tqe_len;
375 first->tqe_mbuf_cnt += lenofoh;
377 TCPSTAT_INC(tcps_rcvoopack);
378 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
379 #ifdef TCP_REASS_LOGGING
380 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m,
387 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m,
388 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint8_t flags)
391 * Free the data in q, and replace
392 * it with the new segment.
396 #ifdef TCP_REASS_LOGGING
397 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0);
400 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
401 ("Tp:%p seg queue goes negative", tp));
402 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
403 q->tqe_mbuf_cnt = mbufoh;
407 if (len > q->tqe_len)
408 len_dif = len - q->tqe_len;
412 TCPSTAT_INC(tcps_rcvoopack);
413 TCPSTAT_ADD(tcps_rcvoobyte, len_dif);
415 q->tqe_flags = (flags & TH_FIN);
416 q->tqe_m->m_pkthdr.len = q->tqe_len;
417 tp->t_segqmbuflen += mbufoh;
422 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent,
426 * Merge q into ent and free q from the list.
428 #ifdef TCP_REASS_LOGGING
429 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0);
431 #ifdef TCP_REASS_COUNTERS
432 counter_u64_add(merge_into, 1);
434 ent->tqe_last->m_next = q->tqe_m;
435 ent->tqe_last = q->tqe_last;
436 ent->tqe_len += q->tqe_len;
437 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt;
438 ent->tqe_m->m_pkthdr.len += q->tqe_len;
439 ent->tqe_flags |= (q->tqe_flags & TH_FIN);
440 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
441 uma_zfree(tcp_reass_zone, q);
447 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent)
449 struct tseg_qent *q, *qtmp;
453 * Given an entry merge forward anyplace
454 * that ent overlaps forward.
457 max = ent->tqe_start + ent->tqe_len;
458 q = TAILQ_NEXT(ent, tqe_q);
463 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) {
464 if (SEQ_GT(q->tqe_start, max)) {
468 /* We have some or all that are overlapping */
469 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) {
470 /* It consumes it all */
471 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
473 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
474 uma_zfree(tcp_reass_zone, q);
479 * Trim the q entry to dovetail to this one
480 * and then merge q into ent updating max
483 i = max - q->tqe_start;
484 #ifdef TCP_REASS_LOGGING
485 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2);
490 tcp_reass_merge_into(tp, ent, q);
491 max = ent->tqe_start + ent->tqe_len;
493 #ifdef TCP_REASS_COUNTERS
494 counter_u64_add(merge_fwd, 1);
499 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast)
503 if (m->m_flags & M_EXT)
504 len += m->m_ext.ext_size;
505 while (m->m_next != NULL) {
508 if (m->m_flags & M_EXT)
509 len += m->m_ext.ext_size;
517 * NOTE!!! the new tcp-reassembly code *must not* use
518 * m_adj() with a negative index. That alters the chain
519 * of mbufs (by possibly chopping trailing mbufs). At
520 * the front of tcp_reass we count the mbuf overhead
521 * and setup the tail pointer. If we use m_adj(m, -5)
522 * we could corrupt the tail pointer. Currently the
523 * code only uses m_adj(m, postive-num). If this
524 * changes appropriate changes to update mlast would
528 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start,
529 int *tlenp, struct mbuf *m)
531 struct tseg_qent *q, *last, *first;
532 struct tseg_qent *p = NULL;
533 struct tseg_qent *nq = NULL;
534 struct tseg_qent *te = NULL;
535 struct mbuf *mlast = NULL;
537 struct socket *so = tp->t_inpcb->inp_socket;
539 int flags, i, lenofoh;
541 INP_WLOCK_ASSERT(tp->t_inpcb);
543 * XXX: tcp_reass() is rather inefficient with its data structures
544 * and should be rewritten (see NetBSD for optimizations).
547 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL),
548 ("tcp_reass called with illegal parameter combination "
549 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)",
550 tp, th, seq_start, tlenp, m));
552 * Call with th==NULL after become established to
553 * force pre-ESTABLISHED data up to user socket.
557 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt),
558 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)",
560 #ifdef TCP_REASS_LOGGING
561 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL);
563 #ifdef TCP_REASS_COUNTERS
564 counter_u64_add(reass_entry, 1);
567 * Check for zero length data.
569 if ((*tlenp == 0) && ((th->th_flags & TH_FIN) == 0)) {
571 * A zero length segment does no
572 * one any good. We could check
573 * the rcv_nxt <-> rcv_wnd but thats
574 * already done for us by the caller.
576 #ifdef TCP_REASS_COUNTERS
577 counter_u64_add(tcp_zero_input, 1);
580 #ifdef TCP_REASS_LOGGING
581 tcp_reass_log_dump(tp);
588 lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
589 sb = &tp->t_inpcb->inp_socket->so_rcv;
590 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
591 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) {
593 TCPSTAT_INC(tcps_rcvreassfull);
594 #ifdef TCP_REASS_COUNTERS
595 counter_u64_add(reass_nospace, 1);
597 #ifdef TCP_REASS_LOGGING
598 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0);
600 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
601 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, "
602 "segment dropped\n", s, __func__);
607 #ifdef TCP_REASS_LOGGING
608 tcp_reass_log_dump(tp);
613 * First lets deal with two common cases, the
614 * segment appends to the back of our collected
615 * segments. Or the segment is the next in line.
617 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q);
619 if ((th->th_flags & TH_FIN) &&
620 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) {
622 * Someone is trying to game us, dump
629 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) &&
630 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) {
631 /* Common case, trailing segment is added */
635 * reassembly buffer |---| |---| |---|
638 #ifdef TCP_REASS_COUNTERS
639 counter_u64_add(reass_path1, 1);
641 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) {
642 i = (last->tqe_start + last->tqe_len) - th->th_seq;
644 #ifdef TCP_REASS_LOGGING
645 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3);
651 /* Complete overlap */
652 TCPSTAT_INC(tcps_rcvduppack);
653 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
655 *tlenp = last->tqe_len;
656 *seq_start = last->tqe_start;
660 if (last->tqe_flags & TH_FIN) {
662 * We have data after the FIN on the last?
668 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh);
669 tp->t_segqmbuflen += lenofoh;
670 *seq_start = last->tqe_start;
671 *tlenp = last->tqe_len;
673 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) {
675 * Second common case, we missed
676 * another one and have something more
682 * reassembly buffer |---| |---| |---|
685 if (last->tqe_flags & TH_FIN) {
687 * We have data after the FIN on the last?
693 #ifdef TCP_REASS_COUNTERS
694 counter_u64_add(reass_path2, 1);
700 /* First segment (it's NULL). */
703 first = TAILQ_FIRST(&tp->t_segq);
704 if (SEQ_LT(th->th_seq, first->tqe_start) &&
705 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) &&
706 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) {
708 * The head of the queue is prepended by this and
709 * it may be the one I want most.
714 * rea: |---| |---| |---|
716 * Note the case we do not deal with here is:
717 * rea= |---| |---| |---|
719 * Due to the fact that it could be
720 * new |--------------------|
721 * And we might need to merge forward.
724 struct mbuf *firstmbuf;
727 #ifdef TCP_REASS_COUNTERS
728 counter_u64_add(reass_path3, 1);
730 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) {
732 * The resend was even before
733 * what we have. We need to trim it.
734 * Note TSNH (it should be trimmed
735 * before the call to tcp_reass()).
738 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed",
739 th->th_seq, tp->rcv_nxt, tp);
741 i = tp->rcv_nxt - th->th_seq;
742 #ifdef TCP_REASS_LOGGING
743 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4);
751 firstmbuf = first->tqe_m;
753 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh);
755 if (firstmbuf == first->tqe_m) {
756 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
757 m, firstmbuf, first->tqe_m, tp, first);
758 } else if (first->tqe_m != m) {
759 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
760 m, firstmbuf, first->tqe_m, tp, first);
763 tp->t_segqmbuflen += lenofoh;
764 *seq_start = first->tqe_start;
765 *tlenp = first->tqe_len;
767 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) {
768 /* New segment is before our earliest segment. */
779 * Find a segment which begins after this one does.
781 #ifdef TCP_REASS_COUNTERS
782 counter_u64_add(reass_fullwalk, 1);
784 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
785 if (SEQ_GT(q->tqe_start, th->th_seq))
788 p = TAILQ_PREV(q, tsegqe_head, tqe_q);
790 * Now is this fit just in-between only?
794 * res= |--| |--| |--|
797 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) &&
798 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) {
803 * If we reach here we have some (possibly all) overlap
805 * res= |--| |--| |--|
807 * or new= |-----------------|
810 * or new= |-----------|
813 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) {
814 /* conversion to int (in i) handles seq wraparound */
816 #ifdef TCP_REASS_COUNTERS
817 counter_u64_add(reass_path4, 1);
819 i = p->tqe_start + p->tqe_len - th->th_seq;
825 * reassembly buffer |---|
828 TCPSTAT_INC(tcps_rcvduppack);
829 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
831 *seq_start = p->tqe_start;
834 * Try to present any queued data
835 * at the left window edge to the user.
836 * This is needed after the 3-WHS
837 * completes. Note this probably
838 * will not work and we will return.
846 * reassembly buffer |---|
847 * new segment |-----|
849 #ifdef TCP_REASS_COUNTERS
850 counter_u64_add(reass_path5, 1);
852 #ifdef TCP_REASS_LOGGING
853 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5);
860 if (th->th_seq == (p->tqe_start + p->tqe_len)) {
862 * If dovetails in with this one
868 * reassembly buffer |--| |---|
870 * (note: it was trimmed above if it overlapped)
872 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh);
873 tp->t_segqmbuflen += lenofoh;
876 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p",
877 th->th_seq, p->tqe_start, p->tqe_len,
887 * The new data runs over the
888 * top of previously sack'd data (in q).
889 * It may be partially overlapping, or
890 * it may overlap the entire segment.
892 #ifdef TCP_REASS_COUNTERS
893 counter_u64_add(reass_path6, 1);
895 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) {
896 /* It consumes it all */
900 * reassembly buffer |--| |---|
901 * new segment |----------|
903 #ifdef TCP_REASS_COUNTERS
904 counter_u64_add(reass_path7, 1);
906 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, th->th_flags);
909 * We just need to prepend the data
910 * to this. It does not overrun
916 * reassembly buffer |--| |---|
917 * new segment |----------|
919 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh);
920 tp->t_segqmbuflen += lenofoh;
923 /* Now does it go further than that? */
924 tcp_reass_merge_forward(tp, q);
925 *seq_start = q->tqe_start;
930 * When we reach here we can't combine it
931 * with any existing segment.
933 * Limit the number of segments that can be queued to reduce the
934 * potential for mbuf exhaustion. For best performance, we want to be
935 * able to queue a full window's worth of segments. The size of the
936 * socket receive buffer determines our advertised window and grows
937 * automatically when socket buffer autotuning is enabled. Use it as the
938 * basis for our queue limit.
940 * However, allow the user to specify a ceiling for the number of
941 * segments in each queue.
943 * Always let the missing segment through which caused this queue.
944 * NB: Access to the socket buffer is left intentionally unlocked as we
945 * can tolerate stale information here.
947 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
948 * should work but causes packets to be dropped when they shouldn't.
949 * Investigate why and re-evaluate the below limit after the behaviour
953 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) {
954 tp->rcv_nxt += *tlenp;
955 flags = th->th_flags & TH_FIN;
956 TCPSTAT_INC(tcps_rcvoopack);
957 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
958 SOCKBUF_LOCK(&so->so_rcv);
959 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
962 sbappendstream_locked(&so->so_rcv, m, 0);
964 sorwakeup_locked(so);
967 if (tcp_new_limits) {
968 if ((tp->t_segqlen > tcp_reass_queue_guard) &&
971 * This is really a lie, we are not full but
972 * are getting a segment that is above
973 * guard threshold. If it is and its below
974 * a mbuf size (256) we drop it if it
975 * can't fill in some place.
977 TCPSTAT_INC(tcps_rcvreassfull);
979 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
980 log(LOG_DEBUG, "%s; %s: queue limit reached, "
981 "segment dropped\n", s, __func__);
985 #ifdef TCP_REASS_LOGGING
986 tcp_reass_log_dump(tp);
991 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
992 tcp_reass_maxqueuelen)) {
993 TCPSTAT_INC(tcps_rcvreassfull);
995 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
996 log(LOG_DEBUG, "%s; %s: queue limit reached, "
997 "segment dropped\n", s, __func__);
1001 #ifdef TCP_REASS_LOGGING
1002 tcp_reass_log_dump(tp);
1008 * Allocate a new queue entry. If we can't, or hit the zone limit
1009 * just drop the pkt.
1011 te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
1013 TCPSTAT_INC(tcps_rcvmemdrop);
1016 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
1018 log(LOG_DEBUG, "%s; %s: global zone limit "
1019 "reached, segment dropped\n", s, __func__);
1026 TCPSTAT_INC(tcps_rcvoopack);
1027 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
1028 /* Insert the new segment queue entry into place. */
1030 te->tqe_flags = th->th_flags;
1031 te->tqe_len = *tlenp;
1032 te->tqe_start = th->th_seq;
1033 te->tqe_last = mlast;
1034 te->tqe_mbuf_cnt = lenofoh;
1035 tp->t_segqmbuflen += te->tqe_mbuf_cnt;
1037 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
1039 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
1041 #ifdef TCP_REASS_LOGGING
1042 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te);
1046 * Present data to user, advancing rcv_nxt through
1047 * completed sequence space.
1049 if (!TCPS_HAVEESTABLISHED(tp->t_state))
1051 q = TAILQ_FIRST(&tp->t_segq);
1052 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt),
1053 ("Reassembly queue for %p has stale entry at head", tp));
1054 if (!q || q->tqe_start != tp->rcv_nxt) {
1055 #ifdef TCP_REASS_LOGGING
1056 tcp_reass_log_dump(tp);
1060 SOCKBUF_LOCK(&so->so_rcv);
1062 tp->rcv_nxt += q->tqe_len;
1063 flags = q->tqe_flags & TH_FIN;
1064 nq = TAILQ_NEXT(q, tqe_q);
1065 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
1066 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
1069 #ifdef TCP_REASS_LOGGING
1070 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q);
1072 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1);
1074 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1);
1077 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
1079 #ifdef TCP_REASS_LOGGING
1081 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2);
1083 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2);
1086 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
1087 ("tp:%p seg queue goes negative", tp));
1088 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
1089 uma_zfree(tcp_reass_zone, q);
1092 } while (q && q->tqe_start == tp->rcv_nxt);
1093 if (TAILQ_EMPTY(&tp->t_segq) &&
1094 (tp->t_segqmbuflen != 0)) {
1096 panic("tp:%p segq:%p len:%d queue empty",
1097 tp, &tp->t_segq, tp->t_segqmbuflen);
1099 #ifdef TCP_REASS_LOGGING
1101 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0);
1103 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0);
1106 tp->t_segqmbuflen = 0;
1109 #ifdef TCP_REASS_LOGGING
1110 tcp_reass_log_dump(tp);
1112 sorwakeup_locked(so);