e407b67be4
mixing on stack memory and UMA memory in one linked list. Thus, rewrite TCP reassembly code in terms of memory usage. The algorithm remains unchanged. We actually do not need extra memory to build a reassembly queue. Arriving mbufs are always packet header mbufs. So we got the length of data as pkthdr.len. We got m_nextpkt for linkage. And we need only one pointer to point at the tcphdr, use PH_loc for that. In tcpcb the t_segq fields becomes mbuf pointer. The t_segqlen field now counts not packets, but bytes in the queue. This gives us more precision when comparing to socket buffer limits. Sponsored by: Netflix Sponsored by: Nginx, Inc.
273 lines
7.3 KiB
C
273 lines
7.3 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/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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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 VNET_DEFINE(int, tcp_reass_overflows) = 0;
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#define V_tcp_reass_overflows VNET(tcp_reass_overflows)
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SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows,
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CTLTYPE_INT | CTLFLAG_RD,
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&VNET_NAME(tcp_reass_overflows), 0,
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"Global number of TCP Segment Reassembly Queue Overflows");
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void
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tcp_reass_flush(struct tcpcb *tp)
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{
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struct mbuf *m;
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INP_WLOCK_ASSERT(tp->t_inpcb);
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while ((m = tp->t_segq) != NULL) {
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tp->t_segq = m->m_nextpkt;
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tp->t_segqlen -= m->m_pkthdr.len;
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m_freem(m);
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}
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KASSERT((tp->t_segqlen == 0),
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("TCP reass queue %p length is %d instead of 0 after flush.",
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tp, tp->t_segqlen));
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}
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#define M_TCPHDR(m) ((struct tcphdr *)((m)->m_pkthdr.pkt_tcphdr))
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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 socket *so = tp->t_inpcb->inp_socket;
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struct mbuf *mq, *mp;
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int flags, wakeup;
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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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M_ASSERTPKTHDR(m);
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KASSERT(*tlenp == m->m_pkthdr.len, ("%s: tlenp %u len %u", __func__,
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*tlenp, m->m_pkthdr.len));
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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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if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
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tp->t_segqlen + m->m_pkthdr.len >= sbspace(&so->so_rcv)) {
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char *s;
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V_tcp_reass_overflows++;
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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: 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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return (0);
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}
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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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mp = NULL;
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for (mq = tp->t_segq; mq != NULL; mq = mq->m_nextpkt) {
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if (SEQ_GT(M_TCPHDR(mq)->th_seq, th->th_seq))
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break;
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mp = mq;
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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 (mp != NULL) {
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int i;
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/* conversion to int (in i) handles seq wraparound */
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i = M_TCPHDR(mp)->th_seq + mp->m_pkthdr.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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/*
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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 (mq) {
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struct mbuf *nq;
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int i;
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i = (th->th_seq + *tlenp) - M_TCPHDR(mq)->th_seq;
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if (i <= 0)
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break;
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if (i < mq->m_pkthdr.len) {
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M_TCPHDR(mq)->th_seq += i;
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m_adj(mq, i);
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tp->t_segqlen -= i;
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break;
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}
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nq = mq->m_nextpkt;
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tp->t_segqlen -= mq->m_pkthdr.len;
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m_freem(mq);
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if (mp)
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mp->m_nextpkt = nq;
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else
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tp->t_segq = nq;
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mq = nq;
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}
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/* Insert the new segment queue entry into place. */
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if (mp) {
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m->m_nextpkt = mp->m_nextpkt;
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mp->m_nextpkt = m;
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} else {
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m->m_nextpkt = tp->t_segq;
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tp->t_segq = m ;
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}
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m->m_pkthdr.pkt_tcphdr = th;
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tp->t_segqlen += m->m_pkthdr.len;
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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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flags = 0;
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wakeup = 0;
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SOCKBUF_LOCK(&so->so_rcv);
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while ((mq = tp->t_segq) != NULL &&
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M_TCPHDR(mq)->th_seq == tp->rcv_nxt) {
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tp->t_segq = mq->m_nextpkt;
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tp->rcv_nxt += mq->m_pkthdr.len;
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tp->t_segqlen -= mq->m_pkthdr.len;
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flags = M_TCPHDR(mq)->th_flags & TH_FIN;
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if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
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m_freem(mq);
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else {
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mq->m_nextpkt = NULL;
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sbappendstream_locked(&so->so_rcv, mq);
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wakeup = 1;
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}
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}
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ND6_HINT(tp);
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if (wakeup)
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sorwakeup_locked(so);
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else
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SOCKBUF_UNLOCK(&so->so_rcv);
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return (flags);
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}
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