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32 #include <sys/cdefs.h>
34 #include "opt_inet6.h"
36 /* For debugging we want counters and BB logging */
37 /* #define TCP_REASS_COUNTERS 1 */
38 /* #define TCP_REASS_LOGGING 1 */
40 #include <sys/param.h>
41 #include <sys/kernel.h>
42 #include <sys/eventhandler.h>
43 #include <sys/malloc.h>
45 #include <sys/socket.h>
46 #include <sys/socketvar.h>
47 #include <sys/sysctl.h>
48 #include <sys/syslog.h>
49 #include <sys/systm.h>
54 #include <net/if_var.h>
55 #include <net/route.h>
58 #include <netinet/in.h>
59 #include <netinet/in_pcb.h>
60 #include <netinet/in_systm.h>
61 #include <netinet/in_var.h>
62 #include <netinet/ip.h>
63 #include <netinet/ip_var.h>
64 #include <netinet/ip_options.h>
65 #include <netinet/ip6.h>
66 #include <netinet6/in6_pcb.h>
67 #include <netinet6/ip6_var.h>
68 #include <netinet6/nd6.h>
69 #include <netinet/tcp.h>
70 #include <netinet/tcp_fsm.h>
71 #include <netinet/tcp_seq.h>
72 #include <netinet/tcp_timer.h>
73 #include <netinet/tcp_var.h>
74 #ifdef TCP_REASS_LOGGING
75 #include <netinet/tcp_log_buf.h>
76 #include <netinet/tcp_hpts.h>
78 #include <netinet/tcpip.h>
80 #define TCP_R_LOG_ADD 1
81 #define TCP_R_LOG_LIMIT_REACHED 2
82 #define TCP_R_LOG_APPEND 3
83 #define TCP_R_LOG_PREPEND 4
84 #define TCP_R_LOG_REPLACE 5
85 #define TCP_R_LOG_MERGE_INTO 6
86 #define TCP_R_LOG_NEW_ENTRY 7
87 #define TCP_R_LOG_READ 8
88 #define TCP_R_LOG_ZERO 9
89 #define TCP_R_LOG_DUMP 10
90 #define TCP_R_LOG_TRIM 11
92 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass,
93 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
94 "TCP Segment Reassembly Queue");
96 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats,
97 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
98 "TCP Segment Reassembly stats");
100 static int tcp_reass_maxseg = 0;
101 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
102 &tcp_reass_maxseg, 0,
103 "Global maximum number of TCP Segments in Reassembly Queue");
105 static uma_zone_t tcp_reass_zone;
106 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
108 "Global number of TCP Segments currently in Reassembly Queue");
110 static u_int tcp_reass_maxqueuelen = 100;
111 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
112 &tcp_reass_maxqueuelen, 0,
113 "Maximum number of TCP Segments per Reassembly Queue");
115 static int tcp_new_limits = 0;
116 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN,
118 "Do we use the new limit method we are discussing?");
120 static u_int tcp_reass_queue_guard = 16;
121 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN,
122 &tcp_reass_queue_guard, 16,
123 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode");
125 #ifdef TCP_REASS_COUNTERS
127 counter_u64_t reass_entry;
128 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD,
129 &reass_entry, "A segment entered reassembly ");
131 counter_u64_t reass_path1;
132 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD,
133 &reass_path1, "Took path 1");
135 counter_u64_t reass_path2;
136 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD,
137 &reass_path2, "Took path 2");
139 counter_u64_t reass_path3;
140 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD,
141 &reass_path3, "Took path 3");
143 counter_u64_t reass_path4;
144 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD,
145 &reass_path4, "Took path 4");
147 counter_u64_t reass_path5;
148 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD,
149 &reass_path5, "Took path 5");
151 counter_u64_t reass_path6;
152 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD,
153 &reass_path6, "Took path 6");
155 counter_u64_t reass_path7;
156 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD,
157 &reass_path7, "Took path 7");
159 counter_u64_t reass_fullwalk;
160 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD,
161 &reass_fullwalk, "Took a full walk ");
163 counter_u64_t reass_nospace;
164 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD,
165 &reass_nospace, "Had no mbuf capacity ");
167 counter_u64_t merge_fwd;
168 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD,
169 &merge_fwd, "Ran merge fwd");
171 counter_u64_t merge_into;
172 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD,
173 &merge_into, "Ran merge into");
175 counter_u64_t tcp_zero_input;
176 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD,
177 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc");
181 /* Initialize TCP reassembly queue */
183 tcp_reass_zone_change(void *tag)
186 /* Set the zone limit and read back the effective value. */
187 tcp_reass_maxseg = nmbclusters / 16;
188 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
192 #ifdef TCP_REASS_LOGGING
195 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p,
196 tcp_seq seq, int len, uint8_t action, int instance)
198 struct socket *so = tptosocket(tp);
202 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
203 union tcp_log_stackspecific log;
205 memset(&log, 0, sizeof(log));
206 cts = tcp_get_usecs(&tv);
207 log.u_bbr.flex1 = seq;
208 log.u_bbr.cur_del_rate = (uint64_t)q;
209 log.u_bbr.delRate = (uint64_t)p;
211 log.u_bbr.flex2 = q->tqe_start;
212 log.u_bbr.flex3 = q->tqe_len;
213 log.u_bbr.flex4 = q->tqe_mbuf_cnt;
214 log.u_bbr.hptsi_gain = q->tqe_flags;
217 log.u_bbr.flex5 = p->tqe_start;
218 log.u_bbr.pkts_out = p->tqe_len;
219 log.u_bbr.epoch = p->tqe_mbuf_cnt;
220 log.u_bbr.cwnd_gain = p->tqe_flags;
222 log.u_bbr.flex6 = tp->t_segqmbuflen;
223 log.u_bbr.flex7 = instance;
224 log.u_bbr.flex8 = action;
225 log.u_bbr.timeStamp = cts;
226 TCP_LOG_EVENTP(tp, NULL, &so->so_rcv, &so->so_snd,
228 len, &log, false, &tv);
233 tcp_reass_log_dump(struct tcpcb *tp)
237 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
238 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
239 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0);
245 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m,
246 int logval, struct tseg_qent *q)
257 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt);
263 tcp_reass_global_init(void)
266 tcp_reass_maxseg = nmbclusters / 16;
267 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
269 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
270 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
271 /* Set the zone limit and read back the effective value. */
272 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
274 #ifdef TCP_REASS_COUNTERS
275 reass_path1 = counter_u64_alloc(M_WAITOK);
276 reass_path2 = counter_u64_alloc(M_WAITOK);
277 reass_path3 = counter_u64_alloc(M_WAITOK);
278 reass_path4 = counter_u64_alloc(M_WAITOK);
279 reass_path5 = counter_u64_alloc(M_WAITOK);
280 reass_path6 = counter_u64_alloc(M_WAITOK);
281 reass_path7 = counter_u64_alloc(M_WAITOK);
282 reass_fullwalk = counter_u64_alloc(M_WAITOK);
283 reass_nospace = counter_u64_alloc(M_WAITOK);
284 reass_entry = counter_u64_alloc(M_WAITOK);
285 merge_fwd = counter_u64_alloc(M_WAITOK);
286 merge_into = counter_u64_alloc(M_WAITOK);
287 tcp_zero_input = counter_u64_alloc(M_WAITOK);
289 EVENTHANDLER_REGISTER(nmbclusters_change,
290 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
295 tcp_reass_flush(struct tcpcb *tp)
297 struct tseg_qent *qe;
299 INP_WLOCK_ASSERT(tptoinpcb(tp));
301 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) {
302 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q);
304 uma_zfree(tcp_reass_zone, qe);
307 tp->t_segqmbuflen = 0;
308 KASSERT((tp->t_segqlen == 0),
309 ("TCP reass queue %p segment count is %d instead of 0 after flush.",
314 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last,
315 struct mbuf *m, struct tcphdr *th, int tlen,
316 struct mbuf *mlast, int lenofoh)
319 #ifdef TCP_REASS_LOGGING
320 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0);
322 last->tqe_len += tlen;
323 last->tqe_m->m_pkthdr.len += tlen;
324 /* Preserve the FIN bit if its there */
325 last->tqe_flags |= (tcp_get_flags(th) & TH_FIN);
326 last->tqe_last->m_next = m;
327 last->tqe_last = mlast;
328 last->tqe_mbuf_cnt += lenofoh;
330 TCPSTAT_INC(tcps_rcvoopack);
331 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
332 #ifdef TCP_REASS_LOGGING
333 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m,
340 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th,
341 int tlen, struct mbuf *mlast, int lenofoh)
345 #ifdef TCP_REASS_LOGGING
346 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0);
348 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) {
349 /* The new data overlaps into the old */
350 i = (th->th_seq + tlen) - first->tqe_start;
351 #ifdef TCP_REASS_LOGGING
352 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1);
354 m_adj(first->tqe_m, i);
356 first->tqe_start += i;
358 /* Ok now setup our chain to point to the old first */
359 mlast->m_next = first->tqe_m;
361 first->tqe_len += tlen;
362 first->tqe_start = th->th_seq;
363 first->tqe_m->m_pkthdr.len = first->tqe_len;
364 first->tqe_mbuf_cnt += lenofoh;
366 TCPSTAT_INC(tcps_rcvoopack);
367 TCPSTAT_ADD(tcps_rcvoobyte, tlen);
368 #ifdef TCP_REASS_LOGGING
369 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m,
376 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m,
377 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags)
380 * Free the data in q, and replace
381 * it with the new segment.
385 #ifdef TCP_REASS_LOGGING
386 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0);
389 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
390 ("Tp:%p seg queue goes negative", tp));
391 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
392 q->tqe_mbuf_cnt = mbufoh;
396 if (len > q->tqe_len)
397 len_dif = len - q->tqe_len;
401 TCPSTAT_INC(tcps_rcvoopack);
402 TCPSTAT_ADD(tcps_rcvoobyte, len_dif);
404 q->tqe_flags = (flags & TH_FIN);
405 q->tqe_m->m_pkthdr.len = q->tqe_len;
406 tp->t_segqmbuflen += mbufoh;
411 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent,
415 * Merge q into ent and free q from the list.
417 #ifdef TCP_REASS_LOGGING
418 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0);
420 #ifdef TCP_REASS_COUNTERS
421 counter_u64_add(merge_into, 1);
423 ent->tqe_last->m_next = q->tqe_m;
424 ent->tqe_last = q->tqe_last;
425 ent->tqe_len += q->tqe_len;
426 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt;
427 ent->tqe_m->m_pkthdr.len += q->tqe_len;
428 ent->tqe_flags |= (q->tqe_flags & TH_FIN);
429 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
430 uma_zfree(tcp_reass_zone, q);
436 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent)
438 struct tseg_qent *q, *qtmp;
442 * Given an entry merge forward anyplace
443 * that ent overlaps forward.
446 max = ent->tqe_start + ent->tqe_len;
447 q = TAILQ_NEXT(ent, tqe_q);
452 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) {
453 if (SEQ_GT(q->tqe_start, max)) {
457 /* We have some or all that are overlapping */
458 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) {
459 /* It consumes it all */
460 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
462 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
463 uma_zfree(tcp_reass_zone, q);
468 * Trim the q entry to dovetail to this one
469 * and then merge q into ent updating max
472 i = max - q->tqe_start;
473 #ifdef TCP_REASS_LOGGING
474 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2);
479 tcp_reass_merge_into(tp, ent, q);
480 max = ent->tqe_start + ent->tqe_len;
482 #ifdef TCP_REASS_COUNTERS
483 counter_u64_add(merge_fwd, 1);
488 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast)
492 if (m->m_flags & M_EXT)
493 len += m->m_ext.ext_size;
494 while (m->m_next != NULL) {
497 if (m->m_flags & M_EXT)
498 len += m->m_ext.ext_size;
505 * NOTE!!! the new tcp-reassembly code *must not* use
506 * m_adj() with a negative index. That alters the chain
507 * of mbufs (by possibly chopping trailing mbufs). At
508 * the front of tcp_reass we count the mbuf overhead
509 * and setup the tail pointer. If we use m_adj(m, -5)
510 * we could corrupt the tail pointer. Currently the
511 * code only uses m_adj(m, postive-num). If this
512 * changes appropriate changes to update mlast would
516 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start,
517 int *tlenp, struct mbuf *m)
519 struct tseg_qent *q, *last, *first;
520 struct tseg_qent *p = NULL;
521 struct tseg_qent *nq = NULL;
522 struct tseg_qent *te = NULL;
523 struct mbuf *mlast = NULL;
524 struct inpcb *inp = tptoinpcb(tp);
525 struct socket *so = tptosocket(tp);
526 struct sockbuf *sb = &so->so_rcv;
528 int flags, i, lenofoh;
530 INP_WLOCK_ASSERT(inp);
532 * XXX: tcp_reass() is rather inefficient with its data structures
533 * and should be rewritten (see NetBSD for optimizations).
536 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL),
537 ("tcp_reass called with illegal parameter combination "
538 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)",
539 tp, th, seq_start, tlenp, m));
541 * Call with th==NULL after become established to
542 * force pre-ESTABLISHED data up to user socket.
546 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt),
547 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)",
549 #ifdef TCP_REASS_LOGGING
550 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL);
552 #ifdef TCP_REASS_COUNTERS
553 counter_u64_add(reass_entry, 1);
556 * Check for zero length data.
558 if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) {
560 * A zero length segment does no
561 * one any good. We could check
562 * the rcv_nxt <-> rcv_wnd but thats
563 * already done for us by the caller.
566 #ifdef TCP_REASS_COUNTERS
567 counter_u64_add(tcp_zero_input, 1);
570 #ifdef TCP_REASS_LOGGING
571 tcp_reass_log_dump(tp);
574 } else if ((*tlenp == 0) &&
575 (tcp_get_flags(th) & TH_FIN) &&
576 !TCPS_HAVEESTABLISHED(tp->t_state)) {
578 * We have not established, and we
579 * have a FIN and no data. Lets treat
580 * this as the same as if the FIN were
581 * not present. We don't want to save
582 * the FIN bit in a reassembly buffer
583 * we want to get established first before
584 * we do that (the peer will retransmit).
591 lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
592 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
593 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) {
595 TCPSTAT_INC(tcps_rcvreassfull);
596 #ifdef TCP_REASS_COUNTERS
597 counter_u64_add(reass_nospace, 1);
599 #ifdef TCP_REASS_LOGGING
600 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0);
602 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
603 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, "
604 "segment dropped\n", s, __func__);
609 #ifdef TCP_REASS_LOGGING
610 tcp_reass_log_dump(tp);
615 * First lets deal with two common cases, the
616 * segment appends to the back of our collected
617 * segments. Or the segment is the next in line.
619 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q);
621 if ((tcp_get_flags(th) & TH_FIN) &&
622 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) {
624 * Someone is trying to game us, dump
631 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) &&
632 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) {
633 /* Common case, trailing segment is added */
637 * reassembly buffer |---| |---| |---|
640 #ifdef TCP_REASS_COUNTERS
641 counter_u64_add(reass_path1, 1);
643 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) {
644 i = (last->tqe_start + last->tqe_len) - th->th_seq;
646 #ifdef TCP_REASS_LOGGING
647 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3);
653 /* Complete overlap */
654 TCPSTAT_INC(tcps_rcvduppack);
655 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
657 *tlenp = last->tqe_len;
658 *seq_start = last->tqe_start;
662 if (last->tqe_flags & TH_FIN) {
664 * We have data after the FIN on the last?
670 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh);
671 tp->t_segqmbuflen += lenofoh;
672 *seq_start = last->tqe_start;
673 *tlenp = last->tqe_len;
675 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) {
677 * Second common case, we missed
678 * another one and have something more
684 * reassembly buffer |---| |---| |---|
687 if (last->tqe_flags & TH_FIN) {
689 * We have data after the FIN on the last?
695 #ifdef TCP_REASS_COUNTERS
696 counter_u64_add(reass_path2, 1);
702 /* First segment (it's NULL). */
705 first = TAILQ_FIRST(&tp->t_segq);
706 if (SEQ_LT(th->th_seq, first->tqe_start) &&
707 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) &&
708 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) {
710 * The head of the queue is prepended by this and
711 * it may be the one I want most.
716 * rea: |---| |---| |---|
718 * Note the case we do not deal with here is:
719 * rea= |---| |---| |---|
721 * Due to the fact that it could be
722 * new |--------------------|
723 * And we might need to merge forward.
726 struct mbuf *firstmbuf;
729 #ifdef TCP_REASS_COUNTERS
730 counter_u64_add(reass_path3, 1);
732 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) {
734 * The resend was even before
735 * what we have. We need to trim it.
736 * Note TSNH (it should be trimmed
737 * before the call to tcp_reass()).
740 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed",
741 th->th_seq, tp->rcv_nxt, tp);
743 i = tp->rcv_nxt - th->th_seq;
744 #ifdef TCP_REASS_LOGGING
745 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4);
753 firstmbuf = first->tqe_m;
755 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh);
757 if (firstmbuf == first->tqe_m) {
758 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
759 m, firstmbuf, first->tqe_m, tp, first);
760 } else if (first->tqe_m != m) {
761 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p",
762 m, firstmbuf, first->tqe_m, tp, first);
765 tp->t_segqmbuflen += lenofoh;
766 *seq_start = first->tqe_start;
767 *tlenp = first->tqe_len;
769 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) {
770 /* New segment is before our earliest segment. */
781 * Find a segment which begins after this one does.
783 #ifdef TCP_REASS_COUNTERS
784 counter_u64_add(reass_fullwalk, 1);
786 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
787 if (SEQ_GT(q->tqe_start, th->th_seq))
790 p = TAILQ_PREV(q, tsegqe_head, tqe_q);
792 * Now is this fit just in-between only?
796 * res= |--| |--| |--|
799 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) &&
800 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) {
805 * If we reach here we have some (possibly all) overlap
807 * res= |--| |--| |--|
809 * or new= |-----------------|
812 * or new= |-----------|
815 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) {
816 /* conversion to int (in i) handles seq wraparound */
818 #ifdef TCP_REASS_COUNTERS
819 counter_u64_add(reass_path4, 1);
821 i = p->tqe_start + p->tqe_len - th->th_seq;
827 * reassembly buffer |---|
830 TCPSTAT_INC(tcps_rcvduppack);
831 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
833 *seq_start = p->tqe_start;
836 * Try to present any queued data
837 * at the left window edge to the user.
838 * This is needed after the 3-WHS
839 * completes. Note this probably
840 * will not work and we will return.
848 * reassembly buffer |---|
849 * new segment |-----|
851 #ifdef TCP_REASS_COUNTERS
852 counter_u64_add(reass_path5, 1);
854 #ifdef TCP_REASS_LOGGING
855 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5);
862 if (th->th_seq == (p->tqe_start + p->tqe_len)) {
864 * If dovetails in with this one
870 * reassembly buffer |--| |---|
872 * (note: it was trimmed above if it overlapped)
874 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh);
875 tp->t_segqmbuflen += lenofoh;
878 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p",
879 th->th_seq, p->tqe_start, p->tqe_len,
889 * The new data runs over the
890 * top of previously sack'd data (in q).
891 * It may be partially overlapping, or
892 * it may overlap the entire segment.
894 #ifdef TCP_REASS_COUNTERS
895 counter_u64_add(reass_path6, 1);
897 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) {
898 /* It consumes it all */
902 * reassembly buffer |--| |---|
903 * new segment |----------|
905 #ifdef TCP_REASS_COUNTERS
906 counter_u64_add(reass_path7, 1);
908 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th));
911 * We just need to prepend the data
912 * to this. It does not overrun
918 * reassembly buffer |--| |---|
919 * new segment |----------|
921 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh);
922 tp->t_segqmbuflen += lenofoh;
925 /* Now does it go further than that? */
926 tcp_reass_merge_forward(tp, q);
927 *seq_start = q->tqe_start;
932 * When we reach here we can't combine it
933 * with any existing segment.
935 * Limit the number of segments that can be queued to reduce the
936 * potential for mbuf exhaustion. For best performance, we want to be
937 * able to queue a full window's worth of segments. The size of the
938 * socket receive buffer determines our advertised window and grows
939 * automatically when socket buffer autotuning is enabled. Use it as the
940 * basis for our queue limit.
942 * However, allow the user to specify a ceiling for the number of
943 * segments in each queue.
945 * Always let the missing segment through which caused this queue.
946 * NB: Access to the socket buffer is left intentionally unlocked as we
947 * can tolerate stale information here.
949 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
950 * should work but causes packets to be dropped when they shouldn't.
951 * Investigate why and re-evaluate the below limit after the behaviour
955 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) {
956 tp->rcv_nxt += *tlenp;
957 flags = tcp_get_flags(th) & TH_FIN;
958 TCPSTAT_INC(tcps_rcvoopack);
959 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
960 SOCKBUF_LOCK(&so->so_rcv);
961 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
964 sbappendstream_locked(&so->so_rcv, m, 0);
966 tp->t_flags |= TF_WAKESOR;
969 if (tcp_new_limits) {
970 if ((tp->t_segqlen > tcp_reass_queue_guard) &&
973 * This is really a lie, we are not full but
974 * are getting a segment that is above
975 * guard threshold. If it is and its below
976 * a mbuf size (256) we drop it if it
977 * can't fill in some place.
979 TCPSTAT_INC(tcps_rcvreassfull);
981 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
982 log(LOG_DEBUG, "%s; %s: queue limit reached, "
983 "segment dropped\n", s, __func__);
987 #ifdef TCP_REASS_LOGGING
988 tcp_reass_log_dump(tp);
993 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
994 tcp_reass_maxqueuelen)) {
995 TCPSTAT_INC(tcps_rcvreassfull);
997 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
998 log(LOG_DEBUG, "%s; %s: queue limit reached, "
999 "segment dropped\n", s, __func__);
1003 #ifdef TCP_REASS_LOGGING
1004 tcp_reass_log_dump(tp);
1010 * Allocate a new queue entry. If we can't, or hit the zone limit
1011 * just drop the pkt.
1013 te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
1015 TCPSTAT_INC(tcps_rcvmemdrop);
1018 if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) {
1019 log(LOG_DEBUG, "%s; %s: global zone limit "
1020 "reached, segment dropped\n", s, __func__);
1027 TCPSTAT_INC(tcps_rcvoopack);
1028 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
1029 /* Insert the new segment queue entry into place. */
1031 te->tqe_flags = tcp_get_flags(th);
1032 te->tqe_len = *tlenp;
1033 te->tqe_start = th->th_seq;
1034 te->tqe_last = mlast;
1035 te->tqe_mbuf_cnt = lenofoh;
1036 tp->t_segqmbuflen += te->tqe_mbuf_cnt;
1038 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
1040 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
1042 #ifdef TCP_REASS_LOGGING
1043 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te);
1047 * Present data to user, advancing rcv_nxt through
1048 * completed sequence space.
1050 if (!TCPS_HAVEESTABLISHED(tp->t_state))
1052 q = TAILQ_FIRST(&tp->t_segq);
1053 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt),
1054 ("Reassembly queue for %p has stale entry at head", tp));
1055 if (!q || q->tqe_start != tp->rcv_nxt) {
1056 #ifdef TCP_REASS_LOGGING
1057 tcp_reass_log_dump(tp);
1061 SOCKBUF_LOCK(&so->so_rcv);
1063 tp->rcv_nxt += q->tqe_len;
1064 flags = q->tqe_flags & TH_FIN;
1065 nq = TAILQ_NEXT(q, tqe_q);
1066 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
1067 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
1070 #ifdef TCP_REASS_LOGGING
1071 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q);
1073 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1);
1075 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1);
1078 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
1080 #ifdef TCP_REASS_LOGGING
1082 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2);
1084 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2);
1087 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt,
1088 ("tp:%p seg queue goes negative", tp));
1089 tp->t_segqmbuflen -= q->tqe_mbuf_cnt;
1090 uma_zfree(tcp_reass_zone, q);
1093 } while (q && q->tqe_start == tp->rcv_nxt);
1094 if (TAILQ_EMPTY(&tp->t_segq) &&
1095 (tp->t_segqmbuflen != 0)) {
1097 panic("tp:%p segq:%p len:%d queue empty",
1098 tp, &tp->t_segq, tp->t_segqmbuflen);
1100 #ifdef TCP_REASS_LOGGING
1102 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0);
1104 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0);
1107 tp->t_segqmbuflen = 0;
1110 #ifdef TCP_REASS_LOGGING
1111 tcp_reass_log_dump(tp);
1113 tp->t_flags |= TF_WAKESOR;