51369649b0
Mainly focus on files that use BSD 3-Clause license. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts. Special thanks to Wind River for providing access to "The Duke of Highlander" tool: an older (2014) run over FreeBSD tree was useful as a starting point.
336 lines
9.5 KiB
C
336 lines
9.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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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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* 3. 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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/* 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, 0);
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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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* 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 >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) {
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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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