The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_reass.c

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/10.4/sys/netinet/tcp_reass.c 337389 2018-08-06 17:50:40Z jtl $");
   34 
   35 #include "opt_inet.h"
   36 #include "opt_inet6.h"
   37 #include "opt_tcpdebug.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/kernel.h>
   41 #include <sys/malloc.h>
   42 #include <sys/mbuf.h>
   43 #include <sys/socket.h>
   44 #include <sys/socketvar.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/syslog.h>
   47 #include <sys/systm.h>
   48 
   49 #include <vm/uma.h>
   50 
   51 #include <net/if.h>
   52 #include <net/route.h>
   53 #include <net/vnet.h>
   54 
   55 #include <netinet/in.h>
   56 #include <netinet/in_pcb.h>
   57 #include <netinet/in_systm.h>
   58 #include <netinet/in_var.h>
   59 #include <netinet/ip.h>
   60 #include <netinet/ip_var.h>
   61 #include <netinet/ip_options.h>
   62 #include <netinet/ip6.h>
   63 #include <netinet6/in6_pcb.h>
   64 #include <netinet6/ip6_var.h>
   65 #include <netinet6/nd6.h>
   66 #include <netinet/tcp.h>
   67 #include <netinet/tcp_fsm.h>
   68 #include <netinet/tcp_seq.h>
   69 #include <netinet/tcp_timer.h>
   70 #include <netinet/tcp_var.h>
   71 #include <netinet6/tcp6_var.h>
   72 #include <netinet/tcpip.h>
   73 #ifdef TCPDEBUG
   74 #include <netinet/tcp_debug.h>
   75 #endif /* TCPDEBUG */
   76 
   77 static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS);
   78 
   79 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
   80     "TCP Segment Reassembly Queue");
   81 
   82 static int tcp_reass_maxseg = 0;
   83 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
   84     &tcp_reass_maxseg, 0,
   85     "Global maximum number of TCP Segments in Reassembly Queue");
   86 
   87 SYSCTL_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments,
   88     (CTLTYPE_INT | CTLFLAG_RD), NULL, 0, &tcp_reass_sysctl_qsize, "I",
   89     "Global number of TCP Segments currently in Reassembly Queue");
   90 
   91 static int tcp_reass_overflows = 0;
   92 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows,
   93     CTLFLAG_RD,
   94     &tcp_reass_overflows, 0,
   95     "Global number of TCP Segment Reassembly Queue Overflows");
   96 
   97 static uma_zone_t tcp_reass_zone;
   98 
   99 static u_int tcp_reass_maxqueuelen = 100;
  100 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
  101     &tcp_reass_maxqueuelen, 0,
  102     "Maximum number of TCP Segments per Reassembly Queue");
  103 
  104 /* Initialize TCP reassembly queue */
  105 static void
  106 tcp_reass_zone_change(void *tag)
  107 {
  108 
  109         /* Set the zone limit and read back the effective value. */
  110         tcp_reass_maxseg = nmbclusters / 16;
  111         tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
  112             tcp_reass_maxseg);
  113 }
  114 
  115 void
  116 tcp_reass_global_init(void)
  117 {
  118 
  119         tcp_reass_maxseg = nmbclusters / 16;
  120         TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
  121             &tcp_reass_maxseg);
  122         tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
  123             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  124         /* Set the zone limit and read back the effective value. */
  125         tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
  126             tcp_reass_maxseg);
  127         EVENTHANDLER_REGISTER(nmbclusters_change,
  128             tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
  129 }
  130 
  131 void
  132 tcp_reass_flush(struct tcpcb *tp)
  133 {
  134         struct tseg_qent *qe;
  135 
  136         INP_WLOCK_ASSERT(tp->t_inpcb);
  137 
  138         while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) {
  139                 LIST_REMOVE(qe, tqe_q);
  140                 m_freem(qe->tqe_m);
  141                 uma_zfree(tcp_reass_zone, qe);
  142                 tp->t_segqlen--;
  143         }
  144 
  145         KASSERT((tp->t_segqlen == 0),
  146             ("TCP reass queue %p segment count is %d instead of 0 after flush.",
  147             tp, tp->t_segqlen));
  148 }
  149 
  150 static int
  151 tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS)
  152 {
  153         int qsize;
  154 
  155         qsize = uma_zone_get_cur(tcp_reass_zone);
  156         return (sysctl_handle_int(oidp, &qsize, 0, req));
  157 }
  158 
  159 int
  160 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
  161 {
  162         struct tseg_qent *q;
  163         struct tseg_qent *p = NULL;
  164         struct tseg_qent *nq;
  165         struct tseg_qent *te = NULL;
  166         struct socket *so = tp->t_inpcb->inp_socket;
  167         char *s = NULL;
  168         int flags;
  169         struct tseg_qent tqs;
  170 
  171         INP_WLOCK_ASSERT(tp->t_inpcb);
  172 
  173         /*
  174          * XXX: tcp_reass() is rather inefficient with its data structures
  175          * and should be rewritten (see NetBSD for optimizations).
  176          */
  177 
  178         /*
  179          * Call with th==NULL after become established to
  180          * force pre-ESTABLISHED data up to user socket.
  181          */
  182         if (th == NULL)
  183                 goto present;
  184 
  185         /*
  186          * Limit the number of segments that can be queued to reduce the
  187          * potential for mbuf exhaustion. For best performance, we want to be
  188          * able to queue a full window's worth of segments. The size of the
  189          * socket receive buffer determines our advertised window and grows
  190          * automatically when socket buffer autotuning is enabled. Use it as the
  191          * basis for our queue limit.
  192          *
  193          * However, allow the user to specify a ceiling for the number of
  194          * segments in each queue.
  195          *
  196          * Always let the missing segment through which caused this queue.
  197          * NB: Access to the socket buffer is left intentionally unlocked as we
  198          * can tolerate stale information here.
  199          *
  200          * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
  201          * should work but causes packets to be dropped when they shouldn't.
  202          * Investigate why and re-evaluate the below limit after the behaviour
  203          * is understood.
  204          */
  205         if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
  206             tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
  207             tcp_reass_maxqueuelen)) {
  208                 tcp_reass_overflows++;
  209                 TCPSTAT_INC(tcps_rcvmemdrop);
  210                 m_freem(m);
  211                 *tlenp = 0;
  212                 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
  213                         log(LOG_DEBUG, "%s; %s: queue limit reached, "
  214                             "segment dropped\n", s, __func__);
  215                         free(s, M_TCPLOG);
  216                 }
  217                 return (0);
  218         }
  219 
  220         /*
  221          * Allocate a new queue entry. If we can't, or hit the zone limit
  222          * just drop the pkt.
  223          *
  224          * Use a temporary structure on the stack for the missing segment
  225          * when the zone is exhausted. Otherwise we may get stuck.
  226          */
  227         te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
  228         if (te == NULL) {
  229                 if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) {
  230                         TCPSTAT_INC(tcps_rcvmemdrop);
  231                         m_freem(m);
  232                         *tlenp = 0;
  233                         if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
  234                             NULL))) {
  235                                 log(LOG_DEBUG, "%s; %s: global zone limit "
  236                                     "reached, segment dropped\n", s, __func__);
  237                                 free(s, M_TCPLOG);
  238                         }
  239                         return (0);
  240                 } else {
  241                         bzero(&tqs, sizeof(struct tseg_qent));
  242                         te = &tqs;
  243                         if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
  244                             NULL))) {
  245                                 log(LOG_DEBUG,
  246                                     "%s; %s: global zone limit reached, using "
  247                                     "stack for missing segment\n", s, __func__);
  248                                 free(s, M_TCPLOG);
  249                         }
  250                 }
  251         }
  252         tp->t_segqlen++;
  253 
  254         /*
  255          * Find a segment which begins after this one does.
  256          */
  257         LIST_FOREACH(q, &tp->t_segq, tqe_q) {
  258                 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
  259                         break;
  260                 p = q;
  261         }
  262 
  263         /*
  264          * If there is a preceding segment, it may provide some of
  265          * our data already.  If so, drop the data from the incoming
  266          * segment.  If it provides all of our data, drop us.
  267          */
  268         if (p != NULL) {
  269                 int i;
  270                 /* conversion to int (in i) handles seq wraparound */
  271                 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
  272                 if (i > 0) {
  273                         if (i >= *tlenp) {
  274                                 TCPSTAT_INC(tcps_rcvduppack);
  275                                 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
  276                                 m_freem(m);
  277                                 if (te != &tqs)
  278                                         uma_zfree(tcp_reass_zone, te);
  279                                 tp->t_segqlen--;
  280                                 /*
  281                                  * Try to present any queued data
  282                                  * at the left window edge to the user.
  283                                  * This is needed after the 3-WHS
  284                                  * completes.
  285                                  */
  286                                 goto present;   /* ??? */
  287                         }
  288                         m_adj(m, i);
  289                         *tlenp -= i;
  290                         th->th_seq += i;
  291                 }
  292         }
  293         tp->t_rcvoopack++;
  294         TCPSTAT_INC(tcps_rcvoopack);
  295         TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
  296 
  297         /*
  298          * While we overlap succeeding segments trim them or,
  299          * if they are completely covered, dequeue them.
  300          */
  301         while (q) {
  302                 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
  303                 if (i <= 0)
  304                         break;
  305                 if (i < q->tqe_len) {
  306                         q->tqe_th->th_seq += i;
  307                         q->tqe_len -= i;
  308                         m_adj(q->tqe_m, i);
  309                         break;
  310                 }
  311 
  312                 nq = LIST_NEXT(q, tqe_q);
  313                 LIST_REMOVE(q, tqe_q);
  314                 m_freem(q->tqe_m);
  315                 uma_zfree(tcp_reass_zone, q);
  316                 tp->t_segqlen--;
  317                 q = nq;
  318         }
  319 
  320         /* Insert the new segment queue entry into place. */
  321         te->tqe_m = m;
  322         te->tqe_th = th;
  323         te->tqe_len = *tlenp;
  324 
  325         if (p == NULL) {
  326                 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
  327         } else {
  328                 KASSERT(te != &tqs, ("%s: temporary stack based entry not "
  329                     "first element in queue", __func__));
  330                 LIST_INSERT_AFTER(p, te, tqe_q);
  331         }
  332 
  333 present:
  334         /*
  335          * Present data to user, advancing rcv_nxt through
  336          * completed sequence space.
  337          */
  338         if (!TCPS_HAVEESTABLISHED(tp->t_state))
  339                 return (0);
  340         q = LIST_FIRST(&tp->t_segq);
  341         if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
  342                 return (0);
  343         SOCKBUF_LOCK(&so->so_rcv);
  344         do {
  345                 tp->rcv_nxt += q->tqe_len;
  346                 flags = q->tqe_th->th_flags & TH_FIN;
  347                 nq = LIST_NEXT(q, tqe_q);
  348                 LIST_REMOVE(q, tqe_q);
  349                 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
  350                         m_freem(q->tqe_m);
  351                 else
  352                         sbappendstream_locked(&so->so_rcv, q->tqe_m);
  353                 if (q != &tqs)
  354                         uma_zfree(tcp_reass_zone, q);
  355                 tp->t_segqlen--;
  356                 q = nq;
  357         } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
  358         ND6_HINT(tp);
  359         sorwakeup_locked(so);
  360         return (flags);
  361 }

Cache object: 48e33f2c73fc828049546494211e6fdb


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.