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- /*-
- * 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.
- *
- * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
- */
- #include <sys/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include "opt_inet.h"
- #include "opt_inet6.h"
- #include "opt_tcpdebug.h"
- /* For debugging we want counters and BB logging */
- /* #define TCP_REASS_COUNTERS 1 */
- /* #define TCP_REASS_LOGGING 1 */
- #include <sys/param.h>
- #include <sys/kernel.h>
- #include <sys/eventhandler.h>
- #include <sys/malloc.h>
- #include <sys/mbuf.h>
- #include <sys/socket.h>
- #include <sys/socketvar.h>
- #include <sys/sysctl.h>
- #include <sys/syslog.h>
- #include <sys/systm.h>
- #include <vm/uma.h>
- #include <net/if.h>
- #include <net/if_var.h>
- #include <net/route.h>
- #include <net/vnet.h>
- #include <netinet/in.h>
- #include <netinet/in_pcb.h>
- #include <netinet/in_systm.h>
- #include <netinet/in_var.h>
- #include <netinet/ip.h>
- #include <netinet/ip_var.h>
- #include <netinet/ip_options.h>
- #include <netinet/ip6.h>
- #include <netinet6/in6_pcb.h>
- #include <netinet6/ip6_var.h>
- #include <netinet6/nd6.h>
- #include <netinet/tcp.h>
- #include <netinet/tcp_fsm.h>
- #include <netinet/tcp_seq.h>
- #include <netinet/tcp_timer.h>
- #include <netinet/tcp_var.h>
- #ifdef TCP_REASS_LOGGING
- #include <netinet/tcp_log_buf.h>
- #include <netinet/tcp_hpts.h>
- #endif
- #include <netinet6/tcp6_var.h>
- #include <netinet/tcpip.h>
- #ifdef TCPDEBUG
- #include <netinet/tcp_debug.h>
- #endif /* TCPDEBUG */
- #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)
- {
- 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,
- &tp->t_inpcb->inp_socket->so_rcv,
- &tp->t_inpcb->inp_socket->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(tp->t_inpcb);
- 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 |= (th->th_flags & 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, uint8_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 sockbuf *sb;
- struct socket *so = tp->t_inpcb->inp_socket;
- char *s = NULL;
- int flags, i, lenofoh;
- INP_WLOCK_ASSERT(tp->t_inpcb);
- /*
- * 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) && ((th->th_flags & 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.
- */
- #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);
- }
- /*
- * Will it fit?
- */
- lenofoh = tcp_reass_overhead_of_chain(m, &mlast);
- sb = &tp->t_inpcb->inp_socket->so_rcv;
- 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(&tp->t_inpcb->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 ((th->th_flags & 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, th->th_flags);
- } 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 = th->th_flags & TH_FIN;
- TCPSTAT_INC(tcps_rcvoopack);
- TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
- SOCKBUF_LOCK(&so->so_rcv);
- if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
- m_freem(m);
- } else {
- sbappendstream_locked(&so->so_rcv, m, 0);
- }
- SOCKBUF_UNLOCK(&so->so_rcv);
- 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(&tp->t_inpcb->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(&tp->t_inpcb->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(&tp->t_inpcb->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 = th->th_flags;
- 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);
- }
- SOCKBUF_LOCK(&so->so_rcv);
- 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
- SOCKBUF_UNLOCK(&so->so_rcv);
- tp->t_flags |= TF_WAKESOR;
- return (flags);
- }
|