/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include "opt_inet.h" #include "opt_inet6.h" /* For debugging we want counters and BB logging */ /* #define TCP_REASS_COUNTERS 1 */ /* #define TCP_REASS_LOGGING 1 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef TCP_REASS_LOGGING #include #include #endif #include #define TCP_R_LOG_ADD 1 #define TCP_R_LOG_LIMIT_REACHED 2 #define TCP_R_LOG_APPEND 3 #define TCP_R_LOG_PREPEND 4 #define TCP_R_LOG_REPLACE 5 #define TCP_R_LOG_MERGE_INTO 6 #define TCP_R_LOG_NEW_ENTRY 7 #define TCP_R_LOG_READ 8 #define TCP_R_LOG_ZERO 9 #define TCP_R_LOG_DUMP 10 #define TCP_R_LOG_TRIM 11 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "TCP Segment Reassembly Queue"); static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "TCP Segment Reassembly stats"); static int tcp_reass_maxseg = 0; SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, &tcp_reass_maxseg, 0, "Global maximum number of TCP Segments in Reassembly Queue"); static uma_zone_t tcp_reass_zone; SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, &tcp_reass_zone, "Global number of TCP Segments currently in Reassembly Queue"); static u_int tcp_reass_maxqueuelen = 100; SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, &tcp_reass_maxqueuelen, 0, "Maximum number of TCP Segments per Reassembly Queue"); static int tcp_new_limits = 0; SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, &tcp_new_limits, 0, "Do we use the new limit method we are discussing?"); static u_int tcp_reass_queue_guard = 16; SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, &tcp_reass_queue_guard, 16, "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); #ifdef TCP_REASS_COUNTERS counter_u64_t reass_entry; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, &reass_entry, "A segment entered reassembly "); counter_u64_t reass_path1; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, &reass_path1, "Took path 1"); counter_u64_t reass_path2; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, &reass_path2, "Took path 2"); counter_u64_t reass_path3; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, &reass_path3, "Took path 3"); counter_u64_t reass_path4; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, &reass_path4, "Took path 4"); counter_u64_t reass_path5; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, &reass_path5, "Took path 5"); counter_u64_t reass_path6; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, &reass_path6, "Took path 6"); counter_u64_t reass_path7; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, &reass_path7, "Took path 7"); counter_u64_t reass_fullwalk; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, &reass_fullwalk, "Took a full walk "); counter_u64_t reass_nospace; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, &reass_nospace, "Had no mbuf capacity "); counter_u64_t merge_fwd; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, &merge_fwd, "Ran merge fwd"); counter_u64_t merge_into; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, &merge_into, "Ran merge into"); counter_u64_t tcp_zero_input; SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); #endif /* Initialize TCP reassembly queue */ static void tcp_reass_zone_change(void *tag) { /* Set the zone limit and read back the effective value. */ tcp_reass_maxseg = nmbclusters / 16; tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg); } #ifdef TCP_REASS_LOGGING static void tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, tcp_seq seq, int len, uint8_t action, int instance) { struct socket *so = tptosocket(tp); uint32_t cts; struct timeval tv; if (tp->t_logstate != TCP_LOG_STATE_OFF) { union tcp_log_stackspecific log; memset(&log, 0, sizeof(log)); cts = tcp_get_usecs(&tv); log.u_bbr.flex1 = seq; log.u_bbr.cur_del_rate = (uint64_t)q; log.u_bbr.delRate = (uint64_t)p; if (q != NULL) { log.u_bbr.flex2 = q->tqe_start; log.u_bbr.flex3 = q->tqe_len; log.u_bbr.flex4 = q->tqe_mbuf_cnt; log.u_bbr.hptsi_gain = q->tqe_flags; } if (p != NULL) { log.u_bbr.flex5 = p->tqe_start; log.u_bbr.pkts_out = p->tqe_len; log.u_bbr.epoch = p->tqe_mbuf_cnt; log.u_bbr.cwnd_gain = p->tqe_flags; } log.u_bbr.flex6 = tp->t_segqmbuflen; log.u_bbr.flex7 = instance; log.u_bbr.flex8 = action; log.u_bbr.timeStamp = cts; TCP_LOG_EVENTP(tp, NULL, &so->so_rcv, &so->so_snd, TCP_LOG_REASS, 0, len, &log, false, &tv); } } static void tcp_reass_log_dump(struct tcpcb *tp) { struct tseg_qent *q; if (tp->t_logstate != TCP_LOG_STATE_OFF) { TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); } }; } static void tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, int logval, struct tseg_qent *q) { int cnt; struct mbuf *t; cnt = 0; t = m; while (t) { cnt += t->m_len; t = t->m_next; } tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); } #endif void tcp_reass_global_init(void) { tcp_reass_maxseg = nmbclusters / 16; TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", &tcp_reass_maxseg); tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); /* Set the zone limit and read back the effective value. */ tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg); #ifdef TCP_REASS_COUNTERS reass_path1 = counter_u64_alloc(M_WAITOK); reass_path2 = counter_u64_alloc(M_WAITOK); reass_path3 = counter_u64_alloc(M_WAITOK); reass_path4 = counter_u64_alloc(M_WAITOK); reass_path5 = counter_u64_alloc(M_WAITOK); reass_path6 = counter_u64_alloc(M_WAITOK); reass_path7 = counter_u64_alloc(M_WAITOK); reass_fullwalk = counter_u64_alloc(M_WAITOK); reass_nospace = counter_u64_alloc(M_WAITOK); reass_entry = counter_u64_alloc(M_WAITOK); merge_fwd = counter_u64_alloc(M_WAITOK); merge_into = counter_u64_alloc(M_WAITOK); tcp_zero_input = counter_u64_alloc(M_WAITOK); #endif EVENTHANDLER_REGISTER(nmbclusters_change, tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); } void tcp_reass_flush(struct tcpcb *tp) { struct tseg_qent *qe; INP_WLOCK_ASSERT(tptoinpcb(tp)); while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); m_freem(qe->tqe_m); uma_zfree(tcp_reass_zone, qe); tp->t_segqlen--; } tp->t_segqmbuflen = 0; KASSERT((tp->t_segqlen == 0), ("TCP reass queue %p segment count is %d instead of 0 after flush.", tp, tp->t_segqlen)); } static void tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, struct mbuf *m, struct tcphdr *th, int tlen, struct mbuf *mlast, int lenofoh) { #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); #endif last->tqe_len += tlen; last->tqe_m->m_pkthdr.len += tlen; /* Preserve the FIN bit if its there */ last->tqe_flags |= (tcp_get_flags(th) & TH_FIN); last->tqe_last->m_next = m; last->tqe_last = mlast; last->tqe_mbuf_cnt += lenofoh; tp->t_rcvoopack++; TCPSTAT_INC(tcps_rcvoopack); TCPSTAT_ADD(tcps_rcvoobyte, tlen); #ifdef TCP_REASS_LOGGING tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, TCP_R_LOG_APPEND, last); #endif } static void tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, int tlen, struct mbuf *mlast, int lenofoh) { int i; #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); #endif if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { /* The new data overlaps into the old */ i = (th->th_seq + tlen) - first->tqe_start; #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); #endif m_adj(first->tqe_m, i); first->tqe_len -= i; first->tqe_start += i; } /* Ok now setup our chain to point to the old first */ mlast->m_next = first->tqe_m; first->tqe_m = m; first->tqe_len += tlen; first->tqe_start = th->th_seq; first->tqe_m->m_pkthdr.len = first->tqe_len; first->tqe_mbuf_cnt += lenofoh; tp->t_rcvoopack++; TCPSTAT_INC(tcps_rcvoopack); TCPSTAT_ADD(tcps_rcvoobyte, tlen); #ifdef TCP_REASS_LOGGING tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, TCP_R_LOG_PREPEND, first); #endif } static void tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint16_t flags) { /* * Free the data in q, and replace * it with the new segment. */ int len_dif; #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); #endif m_freem(q->tqe_m); KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, ("Tp:%p seg queue goes negative", tp)); tp->t_segqmbuflen -= q->tqe_mbuf_cnt; q->tqe_mbuf_cnt = mbufoh; q->tqe_m = m; q->tqe_last = mlast; q->tqe_start = seq; if (len > q->tqe_len) len_dif = len - q->tqe_len; else len_dif = 0; tp->t_rcvoopack++; TCPSTAT_INC(tcps_rcvoopack); TCPSTAT_ADD(tcps_rcvoobyte, len_dif); q->tqe_len = len; q->tqe_flags = (flags & TH_FIN); q->tqe_m->m_pkthdr.len = q->tqe_len; tp->t_segqmbuflen += mbufoh; } static void tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, struct tseg_qent *q) { /* * Merge q into ent and free q from the list. */ #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); #endif #ifdef TCP_REASS_COUNTERS counter_u64_add(merge_into, 1); #endif ent->tqe_last->m_next = q->tqe_m; ent->tqe_last = q->tqe_last; ent->tqe_len += q->tqe_len; ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; ent->tqe_m->m_pkthdr.len += q->tqe_len; ent->tqe_flags |= (q->tqe_flags & TH_FIN); TAILQ_REMOVE(&tp->t_segq, q, tqe_q); uma_zfree(tcp_reass_zone, q); tp->t_segqlen--; } static void tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) { struct tseg_qent *q, *qtmp; int i; tcp_seq max; /* * Given an entry merge forward anyplace * that ent overlaps forward. */ max = ent->tqe_start + ent->tqe_len; q = TAILQ_NEXT(ent, tqe_q); if (q == NULL) { /* Nothing left */ return; } TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { if (SEQ_GT(q->tqe_start, max)) { /* Beyond q */ break; } /* We have some or all that are overlapping */ if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { /* It consumes it all */ tp->t_segqmbuflen -= q->tqe_mbuf_cnt; m_freem(q->tqe_m); TAILQ_REMOVE(&tp->t_segq, q, tqe_q); uma_zfree(tcp_reass_zone, q); tp->t_segqlen--; continue; } /* * Trim the q entry to dovetail to this one * and then merge q into ent updating max * in the process. */ i = max - q->tqe_start; #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); #endif m_adj(q->tqe_m, i); q->tqe_len -= i; q->tqe_start += i; tcp_reass_merge_into(tp, ent, q); max = ent->tqe_start + ent->tqe_len; } #ifdef TCP_REASS_COUNTERS counter_u64_add(merge_fwd, 1); #endif } static int tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) { int len = MSIZE; if (m->m_flags & M_EXT) len += m->m_ext.ext_size; while (m->m_next != NULL) { m = m->m_next; len += MSIZE; if (m->m_flags & M_EXT) len += m->m_ext.ext_size; } *mlast = m; return (len); } /* * NOTE!!! the new tcp-reassembly code *must not* use * m_adj() with a negative index. That alters the chain * of mbufs (by possibly chopping trailing mbufs). At * the front of tcp_reass we count the mbuf overhead * and setup the tail pointer. If we use m_adj(m, -5) * we could corrupt the tail pointer. Currently the * code only uses m_adj(m, postive-num). If this * changes appropriate changes to update mlast would * be needed. */ int tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, int *tlenp, struct mbuf *m) { struct tseg_qent *q, *last, *first; struct tseg_qent *p = NULL; struct tseg_qent *nq = NULL; struct tseg_qent *te = NULL; struct mbuf *mlast = NULL; struct inpcb *inp = tptoinpcb(tp); struct socket *so = tptosocket(tp); struct sockbuf *sb = &so->so_rcv; char *s = NULL; int flags, i, lenofoh; INP_WLOCK_ASSERT(inp); /* * XXX: tcp_reass() is rather inefficient with its data structures * and should be rewritten (see NetBSD for optimizations). */ KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL), ("tcp_reass called with illegal parameter combination " "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)", tp, th, seq_start, tlenp, m)); /* * Call with th==NULL after become established to * force pre-ESTABLISHED data up to user socket. */ if (th == NULL) goto present; KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", th, tp)); #ifdef TCP_REASS_LOGGING tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); #endif #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_entry, 1); #endif /* * Check for zero length data. */ if ((*tlenp == 0) && ((tcp_get_flags(th) & TH_FIN) == 0)) { /* * A zero length segment does no * one any good. We could check * the rcv_nxt <-> rcv_wnd but thats * already done for us by the caller. */ strip_fin: #ifdef TCP_REASS_COUNTERS counter_u64_add(tcp_zero_input, 1); #endif m_freem(m); #ifdef TCP_REASS_LOGGING tcp_reass_log_dump(tp); #endif return (0); } else if ((*tlenp == 0) && (tcp_get_flags(th) & TH_FIN) && !TCPS_HAVEESTABLISHED(tp->t_state)) { /* * We have not established, and we * have a FIN and no data. Lets treat * this as the same as if the FIN were * not present. We don't want to save * the FIN bit in a reassembly buffer * we want to get established first before * we do that (the peer will retransmit). */ goto strip_fin; } /* * Will it fit? */ lenofoh = tcp_reass_overhead_of_chain(m, &mlast); if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { /* No room */ TCPSTAT_INC(tcps_rcvreassfull); #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_nospace, 1); #endif #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); #endif if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { log(LOG_DEBUG, "%s; %s: mbuf count limit reached, " "segment dropped\n", s, __func__); free(s, M_TCPLOG); } m_freem(m); *tlenp = 0; #ifdef TCP_REASS_LOGGING tcp_reass_log_dump(tp); #endif return (0); } /* * First lets deal with two common cases, the * segment appends to the back of our collected * segments. Or the segment is the next in line. */ last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); if (last != NULL) { if ((tcp_get_flags(th) & TH_FIN) && SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { /* * Someone is trying to game us, dump * the segment. */ *tlenp = 0; m_freem(m); return (0); } if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { /* Common case, trailing segment is added */ /** * +--last * v * reassembly buffer |---| |---| |---| * new segment |---| */ #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path1, 1); #endif if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { i = (last->tqe_start + last->tqe_len) - th->th_seq; if (i < *tlenp) { #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); th->th_seq += i; #endif m_adj(m, i); *tlenp -= i; } else { /* Complete overlap */ TCPSTAT_INC(tcps_rcvduppack); TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); m_freem(m); *tlenp = last->tqe_len; *seq_start = last->tqe_start; return (0); } } if (last->tqe_flags & TH_FIN) { /* * We have data after the FIN on the last? */ *tlenp = 0; m_freem(m); return(0); } tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); tp->t_segqmbuflen += lenofoh; *seq_start = last->tqe_start; *tlenp = last->tqe_len; return (0); } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { /* * Second common case, we missed * another one and have something more * for the end. */ /** * +--last * v * reassembly buffer |---| |---| |---| * new segment |---| */ if (last->tqe_flags & TH_FIN) { /* * We have data after the FIN on the last? */ *tlenp = 0; m_freem(m); return(0); } #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path2, 1); #endif p = last; goto new_entry; } } else { /* First segment (it's NULL). */ goto new_entry; } first = TAILQ_FIRST(&tp->t_segq); if (SEQ_LT(th->th_seq, first->tqe_start) && SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { /* * The head of the queue is prepended by this and * it may be the one I want most. */ /** * first-------+ * v * rea: |---| |---| |---| * new: |---| * Note the case we do not deal with here is: * rea= |---| |---| |---| * new= |----| * Due to the fact that it could be * new |--------------------| * And we might need to merge forward. */ #ifdef INVARIANTS struct mbuf *firstmbuf; #endif #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path3, 1); #endif if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { /* * The resend was even before * what we have. We need to trim it. * Note TSNH (it should be trimmed * before the call to tcp_reass()). */ #ifdef INVARIANTS panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", th->th_seq, tp->rcv_nxt, tp); #else i = tp->rcv_nxt - th->th_seq; #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); #endif m_adj(m, i); th->th_seq += i; *tlenp -= i; #endif } #ifdef INVARIANTS firstmbuf = first->tqe_m; #endif tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); #ifdef INVARIANTS if (firstmbuf == first->tqe_m) { panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", m, firstmbuf, first->tqe_m, tp, first); } else if (first->tqe_m != m) { panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", m, firstmbuf, first->tqe_m, tp, first); } #endif tp->t_segqmbuflen += lenofoh; *seq_start = first->tqe_start; *tlenp = first->tqe_len; goto present; } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { /* New segment is before our earliest segment. */ /** * first---->+ * v * rea= |---| .... * new" |---| * */ goto new_entry; } /* * Find a segment which begins after this one does. */ #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_fullwalk, 1); #endif TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { if (SEQ_GT(q->tqe_start, th->th_seq)) break; } p = TAILQ_PREV(q, tsegqe_head, tqe_q); /** * Now is this fit just in-between only? * i.e.: * p---+ +----q * v v * res= |--| |--| |--| * nee |-| */ if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { /* Yep no overlap */ goto new_entry; } /** * If we reach here we have some (possibly all) overlap * such as: * res= |--| |--| |--| * new= |----| * or new= |-----------------| * or new= |--------| * or new= |---| * or new= |-----------| */ if ((p != NULL) && (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { /* conversion to int (in i) handles seq wraparound */ #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path4, 1); #endif i = p->tqe_start + p->tqe_len - th->th_seq; if (i >= 0) { if (i >= *tlenp) { /** * prev seg---->+ * v * reassembly buffer |---| * new segment |-| */ TCPSTAT_INC(tcps_rcvduppack); TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); *tlenp = p->tqe_len; *seq_start = p->tqe_start; m_freem(m); /* * Try to present any queued data * at the left window edge to the user. * This is needed after the 3-WHS * completes. Note this probably * will not work and we will return. */ return (0); } if (i > 0) { /** * prev seg---->+ * v * reassembly buffer |---| * new segment |-----| */ #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path5, 1); #endif #ifdef TCP_REASS_LOGGING tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); #endif m_adj(m, i); *tlenp -= i; th->th_seq += i; } } if (th->th_seq == (p->tqe_start + p->tqe_len)) { /* * If dovetails in with this one * append it. */ /** * prev seg---->+ * v * reassembly buffer |--| |---| * new segment |--| * (note: it was trimmed above if it overlapped) */ tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); tp->t_segqmbuflen += lenofoh; } else { #ifdef INVARIANTS panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", th->th_seq, p->tqe_start, p->tqe_len, p, tp); #endif *tlenp = 0; m_freem(m); return (0); } q = p; } else { /* * The new data runs over the * top of previously sack'd data (in q). * It may be partially overlapping, or * it may overlap the entire segment. */ #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path6, 1); #endif if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { /* It consumes it all */ /** * next seg---->+ * v * reassembly buffer |--| |---| * new segment |----------| */ #ifdef TCP_REASS_COUNTERS counter_u64_add(reass_path7, 1); #endif tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, tcp_get_flags(th)); } else { /* * We just need to prepend the data * to this. It does not overrun * the end. */ /** * next seg---->+ * v * reassembly buffer |--| |---| * new segment |----------| */ tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); tp->t_segqmbuflen += lenofoh; } } /* Now does it go further than that? */ tcp_reass_merge_forward(tp, q); *seq_start = q->tqe_start; *tlenp = q->tqe_len; goto present; /* * When we reach here we can't combine it * with any existing segment. * * Limit the number of segments that can be queued to reduce the * potential for mbuf exhaustion. For best performance, we want to be * able to queue a full window's worth of segments. The size of the * socket receive buffer determines our advertised window and grows * automatically when socket buffer autotuning is enabled. Use it as the * basis for our queue limit. * * However, allow the user to specify a ceiling for the number of * segments in each queue. * * Always let the missing segment through which caused this queue. * NB: Access to the socket buffer is left intentionally unlocked as we * can tolerate stale information here. * * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat * should work but causes packets to be dropped when they shouldn't. * Investigate why and re-evaluate the below limit after the behaviour * is understood. */ new_entry: if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) { tp->rcv_nxt += *tlenp; flags = tcp_get_flags(th) & TH_FIN; TCPSTAT_INC(tcps_rcvoopack); TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); SOCK_RECVBUF_LOCK(so); if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { m_freem(m); } else { sbappendstream_locked(&so->so_rcv, m, 0); } tp->t_flags |= TF_WAKESOR; return (flags); } if (tcp_new_limits) { if ((tp->t_segqlen > tcp_reass_queue_guard) && (*tlenp < MSIZE)) { /* * This is really a lie, we are not full but * are getting a segment that is above * guard threshold. If it is and its below * a mbuf size (256) we drop it if it * can't fill in some place. */ TCPSTAT_INC(tcps_rcvreassfull); *tlenp = 0; if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { log(LOG_DEBUG, "%s; %s: queue limit reached, " "segment dropped\n", s, __func__); free(s, M_TCPLOG); } m_freem(m); #ifdef TCP_REASS_LOGGING tcp_reass_log_dump(tp); #endif return (0); } } else { if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, tcp_reass_maxqueuelen)) { TCPSTAT_INC(tcps_rcvreassfull); *tlenp = 0; if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { log(LOG_DEBUG, "%s; %s: queue limit reached, " "segment dropped\n", s, __func__); free(s, M_TCPLOG); } m_freem(m); #ifdef TCP_REASS_LOGGING tcp_reass_log_dump(tp); #endif return (0); } } /* * Allocate a new queue entry. If we can't, or hit the zone limit * just drop the pkt. */ te = uma_zalloc(tcp_reass_zone, M_NOWAIT); if (te == NULL) { TCPSTAT_INC(tcps_rcvmemdrop); m_freem(m); *tlenp = 0; if ((s = tcp_log_addrs(&inp->inp_inc, th, NULL, NULL))) { log(LOG_DEBUG, "%s; %s: global zone limit " "reached, segment dropped\n", s, __func__); free(s, M_TCPLOG); } return (0); } tp->t_segqlen++; tp->t_rcvoopack++; TCPSTAT_INC(tcps_rcvoopack); TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); /* Insert the new segment queue entry into place. */ te->tqe_m = m; te->tqe_flags = tcp_get_flags(th); te->tqe_len = *tlenp; te->tqe_start = th->th_seq; te->tqe_last = mlast; te->tqe_mbuf_cnt = lenofoh; tp->t_segqmbuflen += te->tqe_mbuf_cnt; if (p == NULL) { TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); } else { TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); } #ifdef TCP_REASS_LOGGING tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); #endif present: /* * Present data to user, advancing rcv_nxt through * completed sequence space. */ if (!TCPS_HAVEESTABLISHED(tp->t_state)) return (0); q = TAILQ_FIRST(&tp->t_segq); KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), ("Reassembly queue for %p has stale entry at head", tp)); if (!q || q->tqe_start != tp->rcv_nxt) { #ifdef TCP_REASS_LOGGING tcp_reass_log_dump(tp); #endif return (0); } SOCK_RECVBUF_LOCK(so); do { tp->rcv_nxt += q->tqe_len; flags = q->tqe_flags & TH_FIN; nq = TAILQ_NEXT(q, tqe_q); TAILQ_REMOVE(&tp->t_segq, q, tqe_q); if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { m_freem(q->tqe_m); } else { #ifdef TCP_REASS_LOGGING tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); if (th != NULL) { tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); } else { tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1); } #endif sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); } #ifdef TCP_REASS_LOGGING if (th != NULL) { tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); } else { tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2); } #endif KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, ("tp:%p seg queue goes negative", tp)); tp->t_segqmbuflen -= q->tqe_mbuf_cnt; uma_zfree(tcp_reass_zone, q); tp->t_segqlen--; q = nq; } while (q && q->tqe_start == tp->rcv_nxt); if (TAILQ_EMPTY(&tp->t_segq) && (tp->t_segqmbuflen != 0)) { #ifdef INVARIANTS panic("tp:%p segq:%p len:%d queue empty", tp, &tp->t_segq, tp->t_segqmbuflen); #else #ifdef TCP_REASS_LOGGING if (th != NULL) { tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); } else { tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0); } #endif tp->t_segqmbuflen = 0; #endif } #ifdef TCP_REASS_LOGGING tcp_reass_log_dump(tp); #endif tp->t_flags |= TF_WAKESOR; return (flags); }