344 lines
9.8 KiB
C
344 lines
9.8 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/eventhandler.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <sys/syslog.h>
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#include <sys/systm.h>
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#include <vm/uma.h>
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#include <net/if.h>
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#include <net/if_var.h>
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#include <net/route.h>
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#include <net/vnet.h>
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#include <netinet/in.h>
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#include <netinet/in_pcb.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_options.h>
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#include <netinet/ip6.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/nd6.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet6/tcp6_var.h>
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#include <netinet/tcpip.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif /* TCPDEBUG */
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static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
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"TCP Segment Reassembly Queue");
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static int tcp_reass_maxseg = 0;
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SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
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&tcp_reass_maxseg, 0,
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"Global maximum number of TCP Segments in Reassembly Queue");
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static uma_zone_t tcp_reass_zone;
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SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0,
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&tcp_reass_zone,
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"Global number of TCP Segments currently in Reassembly Queue");
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static u_int tcp_reass_maxqueuelen = 100;
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SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN,
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&tcp_reass_maxqueuelen, 0,
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"Maximum number of TCP Segments per Reassembly Queue");
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/* Initialize TCP reassembly queue */
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static void
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tcp_reass_zone_change(void *tag)
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{
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/* Set the zone limit and read back the effective value. */
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tcp_reass_maxseg = nmbclusters / 16;
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tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
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tcp_reass_maxseg);
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}
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void
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tcp_reass_global_init(void)
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{
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tcp_reass_maxseg = nmbclusters / 16;
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TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
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&tcp_reass_maxseg);
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tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
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/* Set the zone limit and read back the effective value. */
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tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone,
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tcp_reass_maxseg);
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EVENTHANDLER_REGISTER(nmbclusters_change,
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tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
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}
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void
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tcp_reass_flush(struct tcpcb *tp)
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{
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struct tseg_qent *qe;
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INP_WLOCK_ASSERT(tp->t_inpcb);
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while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) {
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LIST_REMOVE(qe, tqe_q);
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m_freem(qe->tqe_m);
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uma_zfree(tcp_reass_zone, qe);
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tp->t_segqlen--;
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}
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KASSERT((tp->t_segqlen == 0),
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("TCP reass queue %p segment count is %d instead of 0 after flush.",
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tp, tp->t_segqlen));
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}
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int
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tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
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{
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struct tseg_qent *q;
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struct tseg_qent *p = NULL;
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struct tseg_qent *nq;
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struct tseg_qent *te = NULL;
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struct socket *so = tp->t_inpcb->inp_socket;
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char *s = NULL;
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int flags;
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struct tseg_qent tqs;
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INP_WLOCK_ASSERT(tp->t_inpcb);
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/*
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* XXX: tcp_reass() is rather inefficient with its data structures
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* and should be rewritten (see NetBSD for optimizations).
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*/
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/*
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* Call with th==NULL after become established to
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* force pre-ESTABLISHED data up to user socket.
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*/
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if (th == NULL)
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goto present;
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/*
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* Limit the number of segments that can be queued to reduce the
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* potential for mbuf exhaustion. For best performance, we want to be
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* able to queue a full window's worth of segments. The size of the
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* socket receive buffer determines our advertised window and grows
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* automatically when socket buffer autotuning is enabled. Use it as the
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* basis for our queue limit.
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*
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* However, allow the user to specify a ceiling for the number of
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* segments in each queue.
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*
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* Always let the missing segment through which caused this queue.
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* NB: Access to the socket buffer is left intentionally unlocked as we
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* can tolerate stale information here.
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*
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* XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat
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* should work but causes packets to be dropped when they shouldn't.
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* Investigate why and re-evaluate the below limit after the behaviour
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* is understood.
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*/
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if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
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tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1,
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tcp_reass_maxqueuelen)) {
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TCPSTAT_INC(tcps_rcvreassfull);
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*tlenp = 0;
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if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
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log(LOG_DEBUG, "%s; %s: queue limit reached, "
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"segment dropped\n", s, __func__);
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free(s, M_TCPLOG);
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}
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m_freem(m);
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return (0);
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}
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/*
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* Allocate a new queue entry. If we can't, or hit the zone limit
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* just drop the pkt.
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*
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* Use a temporary structure on the stack for the missing segment
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* when the zone is exhausted. Otherwise we may get stuck.
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*/
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te = uma_zalloc(tcp_reass_zone, M_NOWAIT);
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if (te == NULL) {
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if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) {
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TCPSTAT_INC(tcps_rcvmemdrop);
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m_freem(m);
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*tlenp = 0;
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if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
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NULL))) {
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log(LOG_DEBUG, "%s; %s: global zone limit "
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"reached, segment dropped\n", s, __func__);
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free(s, M_TCPLOG);
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}
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return (0);
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} else {
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bzero(&tqs, sizeof(struct tseg_qent));
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te = &tqs;
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if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
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NULL))) {
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log(LOG_DEBUG,
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"%s; %s: global zone limit reached, using "
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"stack for missing segment\n", s, __func__);
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free(s, M_TCPLOG);
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}
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}
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}
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tp->t_segqlen++;
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/*
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* Find a segment which begins after this one does.
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*/
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LIST_FOREACH(q, &tp->t_segq, tqe_q) {
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if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
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break;
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p = q;
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}
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/*
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* If there is a preceding segment, it may provide some of
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* our data already. If so, drop the data from the incoming
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* segment. If it provides all of our data, drop us.
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*/
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if (p != NULL) {
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int i;
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/* conversion to int (in i) handles seq wraparound */
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i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
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if (i > 0) {
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if (i >= *tlenp) {
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TCPSTAT_INC(tcps_rcvduppack);
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TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
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m_freem(m);
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if (te != &tqs)
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uma_zfree(tcp_reass_zone, te);
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tp->t_segqlen--;
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/*
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* Try to present any queued data
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* at the left window edge to the user.
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* This is needed after the 3-WHS
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* completes.
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*/
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goto present; /* ??? */
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}
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m_adj(m, i);
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*tlenp -= i;
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th->th_seq += i;
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}
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}
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tp->t_rcvoopack++;
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TCPSTAT_INC(tcps_rcvoopack);
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TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
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/*
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* While we overlap succeeding segments trim them or,
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* if they are completely covered, dequeue them.
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*/
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while (q) {
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int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
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if (i <= 0)
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break;
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if (i < q->tqe_len) {
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q->tqe_th->th_seq += i;
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q->tqe_len -= i;
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m_adj(q->tqe_m, i);
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break;
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}
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nq = LIST_NEXT(q, tqe_q);
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LIST_REMOVE(q, tqe_q);
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m_freem(q->tqe_m);
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uma_zfree(tcp_reass_zone, q);
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tp->t_segqlen--;
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q = nq;
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}
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/* Insert the new segment queue entry into place. */
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te->tqe_m = m;
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te->tqe_th = th;
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te->tqe_len = *tlenp;
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if (p == NULL) {
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LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
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} else {
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KASSERT(te != &tqs, ("%s: temporary stack based entry not "
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"first element in queue", __func__));
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LIST_INSERT_AFTER(p, te, tqe_q);
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}
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present:
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/*
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* Present data to user, advancing rcv_nxt through
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* completed sequence space.
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*/
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if (!TCPS_HAVEESTABLISHED(tp->t_state))
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return (0);
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q = LIST_FIRST(&tp->t_segq);
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if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
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return (0);
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SOCKBUF_LOCK(&so->so_rcv);
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do {
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tp->rcv_nxt += q->tqe_len;
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flags = q->tqe_th->th_flags & TH_FIN;
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nq = LIST_NEXT(q, tqe_q);
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LIST_REMOVE(q, tqe_q);
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if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
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m_freem(q->tqe_m);
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else
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sbappendstream_locked(&so->so_rcv, q->tqe_m, 0);
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if (q != &tqs)
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uma_zfree(tcp_reass_zone, q);
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tp->t_segqlen--;
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q = nq;
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} while (q && q->tqe_th->th_seq == tp->rcv_nxt);
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sorwakeup_locked(so);
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return (flags);
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}
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