3367 lines
87 KiB
C
3367 lines
87 KiB
C
/* $NetBSD: tcp_input.c,v 1.89 1999/07/22 12:56:56 itojun Exp $ */
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/*
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%%% portions-copyright-nrl-95
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Portions of this software are Copyright 1995-1998 by Randall Atkinson,
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Ronald Lee, Daniel McDonald, Bao Phan, and Chris Winters. All Rights
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Reserved. All rights under this copyright have been assigned to the US
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Naval Research Laboratory (NRL). The NRL Copyright Notice and License
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Agreement Version 1.1 (January 17, 1995) applies to these portions of the
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software.
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You should have received a copy of the license with this software. If you
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didn't get a copy, you may request one from <license@ipv6.nrl.navy.mil>.
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*/
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/*
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* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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* 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 project 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 PROJECT 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 PROJECT 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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/*-
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* Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation
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* Facility, NASA Ames Research Center.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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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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/*
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* TODO list for SYN cache stuff:
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*
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* Find room for a "state" field, which is needed to keep a
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* compressed state for TIME_WAIT TCBs. It's been noted already
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* that this is fairly important for very high-volume web and
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* mail servers, which use a large number of short-lived
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* connections.
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*/
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#include "opt_inet.h"
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#include "opt_ipsec.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/errno.h>
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#include <sys/syslog.h>
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#include <sys/pool.h>
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#include <sys/domain.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <net/if_types.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#ifdef INET6
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#ifndef INET
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#include <netinet/in.h>
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#endif
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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/in6_var.h>
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#include <netinet/icmp6.h>
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#endif
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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 <netinet/tcpip.h>
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#include <netinet/tcp_debug.h>
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#include <machine/stdarg.h>
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#ifdef IPSEC
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#include <netinet6/ipsec.h>
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#include <netkey/key.h>
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#include <netkey/key_debug.h>
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#endif /*IPSEC*/
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#ifdef INET6
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#include "faith.h"
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#endif
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int tcprexmtthresh = 3;
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int tcp_log_refused;
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#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ)
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/* for modulo comparisons of timestamps */
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#define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
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#define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
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/*
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* Macro to compute ACK transmission behavior. Delay the ACK unless
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* we have already delayed an ACK (must send an ACK every two segments).
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* We also ACK immediately if we received a PUSH and the ACK-on-PUSH
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* option is enabled.
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*/
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#define TCP_SETUP_ACK(tp, th) \
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do { \
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if ((tp)->t_flags & TF_DELACK || \
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(tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \
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tp->t_flags |= TF_ACKNOW; \
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else \
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TCP_SET_DELACK(tp); \
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} while (0)
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int
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tcp_reass(tp, th, m, tlen)
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register struct tcpcb *tp;
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register struct tcphdr *th;
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struct mbuf *m;
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int *tlen;
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{
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register struct ipqent *p, *q, *nq, *tiqe = NULL;
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struct socket *so = NULL;
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int pkt_flags;
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tcp_seq pkt_seq;
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unsigned pkt_len;
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u_long rcvpartdupbyte = 0;
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u_long rcvoobyte;
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if (tp->t_inpcb)
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so = tp->t_inpcb->inp_socket;
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#ifdef INET6
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else if (tp->t_in6pcb)
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so = tp->t_in6pcb->in6p_socket;
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#endif
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TCP_REASS_LOCK_CHECK(tp);
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/*
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* Call with th==0 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 == 0)
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goto present;
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rcvoobyte = *tlen;
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/*
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* Copy these to local variables because the tcpiphdr
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* gets munged while we are collapsing mbufs.
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*/
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pkt_seq = th->th_seq;
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pkt_len = *tlen;
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pkt_flags = th->th_flags;
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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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for (p = NULL, q = tp->segq.lh_first; q != NULL; q = nq) {
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nq = q->ipqe_q.le_next;
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/*
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* If the received segment is just right after this
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* fragment, merge the two together and then check
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* for further overlaps.
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*/
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if (q->ipqe_seq + q->ipqe_len == pkt_seq) {
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#ifdef TCPREASS_DEBUG
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printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n",
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tp, pkt_seq, pkt_seq + pkt_len, pkt_len,
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q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len);
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#endif
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pkt_len += q->ipqe_len;
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pkt_flags |= q->ipqe_flags;
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pkt_seq = q->ipqe_seq;
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m_cat(q->ipqe_m, m);
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m = q->ipqe_m;
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goto free_ipqe;
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}
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/*
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* If the received segment is completely past this
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* fragment, we need to go the next fragment.
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*/
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if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) {
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p = q;
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continue;
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}
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/*
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* If the fragment is past the received segment,
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* it (or any following) can't be concatenated.
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*/
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if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len))
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break;
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/*
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* We've received all the data in this segment before.
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* mark it as a duplicate and return.
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*/
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if (SEQ_LEQ(q->ipqe_seq, pkt_seq) &&
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SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) {
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tcpstat.tcps_rcvduppack++;
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tcpstat.tcps_rcvdupbyte += pkt_len;
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m_freem(m);
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if (tiqe != NULL)
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pool_put(&ipqent_pool, tiqe);
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return (0);
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}
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/*
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* Received segment completely overlaps this fragment
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* so we drop the fragment (this keeps the temporal
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* ordering of segments correct).
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*/
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if (SEQ_GEQ(q->ipqe_seq, pkt_seq) &&
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SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) {
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rcvpartdupbyte += q->ipqe_len;
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m_freem(q->ipqe_m);
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goto free_ipqe;
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}
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/*
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* RX'ed segment extends past the end of the
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* fragment. Drop the overlapping bytes. Then
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* merge the fragment and segment then treat as
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* a longer received packet.
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*/
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if (SEQ_LT(q->ipqe_seq, pkt_seq)
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&& SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) {
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int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq;
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#ifdef TCPREASS_DEBUG
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printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n",
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tp, overlap,
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pkt_seq, pkt_seq + pkt_len, pkt_len);
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#endif
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m_adj(m, overlap);
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rcvpartdupbyte += overlap;
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m_cat(q->ipqe_m, m);
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m = q->ipqe_m;
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pkt_seq = q->ipqe_seq;
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pkt_len += q->ipqe_len - overlap;
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rcvoobyte -= overlap;
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goto free_ipqe;
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}
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/*
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* RX'ed segment extends past the front of the
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* fragment. Drop the overlapping bytes on the
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* received packet. The packet will then be
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* contatentated with this fragment a bit later.
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*/
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if (SEQ_GT(q->ipqe_seq, pkt_seq)
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&& SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) {
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int overlap = pkt_seq + pkt_len - q->ipqe_seq;
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#ifdef TCPREASS_DEBUG
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printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n",
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tp, overlap,
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pkt_seq, pkt_seq + pkt_len, pkt_len);
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#endif
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m_adj(m, -overlap);
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pkt_len -= overlap;
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rcvpartdupbyte += overlap;
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rcvoobyte -= overlap;
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}
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/*
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* If the received segment immediates precedes this
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* fragment then tack the fragment onto this segment
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* and reinsert the data.
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*/
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if (q->ipqe_seq == pkt_seq + pkt_len) {
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#ifdef TCPREASS_DEBUG
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printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n",
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tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len,
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pkt_seq, pkt_seq + pkt_len, pkt_len);
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#endif
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pkt_len += q->ipqe_len;
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pkt_flags |= q->ipqe_flags;
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m_cat(m, q->ipqe_m);
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LIST_REMOVE(q, ipqe_q);
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LIST_REMOVE(q, ipqe_timeq);
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if (tiqe == NULL) {
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tiqe = q;
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} else {
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pool_put(&ipqent_pool, q);
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}
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break;
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}
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/*
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* If the fragment is before the segment, remember it.
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* When this loop is terminated, p will contain the
|
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* pointer to fragment that is right before the received
|
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* segment.
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*/
|
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if (SEQ_LEQ(q->ipqe_seq, pkt_seq))
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p = q;
|
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|
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continue;
|
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|
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/*
|
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* This is a common operation. It also will allow
|
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* to save doing a malloc/free in most instances.
|
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*/
|
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free_ipqe:
|
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LIST_REMOVE(q, ipqe_q);
|
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LIST_REMOVE(q, ipqe_timeq);
|
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if (tiqe == NULL) {
|
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tiqe = q;
|
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} else {
|
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pool_put(&ipqent_pool, q);
|
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}
|
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}
|
|
|
|
/*
|
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* Allocate a new queue entry since the received segment did not
|
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* collapse onto any other out-of-order block; thus we are allocating
|
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* a new block. If it had collapsed, tiqe would not be NULL and
|
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* we would be reusing it.
|
|
* XXX If we can't, just drop the packet. XXX
|
|
*/
|
|
if (tiqe == NULL) {
|
|
tiqe = pool_get(&ipqent_pool, PR_NOWAIT);
|
|
if (tiqe == NULL) {
|
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tcpstat.tcps_rcvmemdrop++;
|
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m_freem(m);
|
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return (0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Update the counters.
|
|
*/
|
|
tcpstat.tcps_rcvoopack++;
|
|
tcpstat.tcps_rcvoobyte += rcvoobyte;
|
|
if (rcvpartdupbyte) {
|
|
tcpstat.tcps_rcvpartduppack++;
|
|
tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte;
|
|
}
|
|
|
|
/*
|
|
* Insert the new fragment queue entry into both queues.
|
|
*/
|
|
tiqe->ipqe_m = m;
|
|
tiqe->ipqe_seq = pkt_seq;
|
|
tiqe->ipqe_len = pkt_len;
|
|
tiqe->ipqe_flags = pkt_flags;
|
|
if (p == NULL) {
|
|
LIST_INSERT_HEAD(&tp->segq, tiqe, ipqe_q);
|
|
#ifdef TCPREASS_DEBUG
|
|
if (tiqe->ipqe_seq != tp->rcv_nxt)
|
|
printf("tcp_reass[%p]: insert %u:%u(%u) at front\n",
|
|
tp, pkt_seq, pkt_seq + pkt_len, pkt_len);
|
|
#endif
|
|
} else {
|
|
LIST_INSERT_AFTER(p, tiqe, ipqe_q);
|
|
#ifdef TCPREASS_DEBUG
|
|
printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n",
|
|
tp, pkt_seq, pkt_seq + pkt_len, pkt_len,
|
|
p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len);
|
|
#endif
|
|
}
|
|
|
|
LIST_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq);
|
|
|
|
present:
|
|
/*
|
|
* Present data to user, advancing rcv_nxt through
|
|
* completed sequence space.
|
|
*/
|
|
if (TCPS_HAVEESTABLISHED(tp->t_state) == 0)
|
|
return (0);
|
|
q = tp->segq.lh_first;
|
|
if (q == NULL || q->ipqe_seq != tp->rcv_nxt)
|
|
return (0);
|
|
if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len)
|
|
return (0);
|
|
|
|
tp->rcv_nxt += q->ipqe_len;
|
|
pkt_flags = q->ipqe_flags & TH_FIN;
|
|
|
|
LIST_REMOVE(q, ipqe_q);
|
|
LIST_REMOVE(q, ipqe_timeq);
|
|
if (so->so_state & SS_CANTRCVMORE)
|
|
m_freem(q->ipqe_m);
|
|
else
|
|
sbappend(&so->so_rcv, q->ipqe_m);
|
|
pool_put(&ipqent_pool, q);
|
|
sorwakeup(so);
|
|
return (pkt_flags);
|
|
}
|
|
|
|
#if defined(INET6) && !defined(TCP6)
|
|
int
|
|
tcp6_input(mp, offp, proto)
|
|
struct mbuf **mp;
|
|
int *offp, proto;
|
|
{
|
|
struct mbuf *m = *mp;
|
|
|
|
#if defined(NFAITH) && 0 < NFAITH
|
|
if (m->m_pkthdr.rcvif) {
|
|
if (m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
|
|
/* XXX send icmp6 host/port unreach? */
|
|
m_freem(m);
|
|
return IPPROTO_DONE;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* draft-itojun-ipv6-tcp-to-anycast
|
|
* better place to put this in?
|
|
*/
|
|
if (m->m_flags & M_ANYCAST6) {
|
|
if (m->m_len >= sizeof(struct ip6_hdr)) {
|
|
struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
|
|
icmp6_error(m, ICMP6_DST_UNREACH,
|
|
ICMP6_DST_UNREACH_ADDR,
|
|
(caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
|
|
} else
|
|
m_freem(m);
|
|
return IPPROTO_DONE;
|
|
}
|
|
|
|
tcp_input(m, *offp, proto);
|
|
return IPPROTO_DONE;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* TCP input routine, follows pages 65-76 of the
|
|
* protocol specification dated September, 1981 very closely.
|
|
*/
|
|
void
|
|
#if __STDC__
|
|
tcp_input(struct mbuf *m, ...)
|
|
#else
|
|
tcp_input(m, va_alist)
|
|
register struct mbuf *m;
|
|
#endif
|
|
{
|
|
int proto;
|
|
register struct tcphdr *th;
|
|
struct ip *ip;
|
|
register struct inpcb *inp;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6;
|
|
register struct in6pcb *in6p;
|
|
#endif
|
|
caddr_t optp = NULL;
|
|
int optlen = 0;
|
|
int len, tlen, toff, hdroptlen = 0;
|
|
register struct tcpcb *tp = 0;
|
|
register int tiflags;
|
|
struct socket *so = NULL;
|
|
int todrop, acked, ourfinisacked, needoutput = 0;
|
|
short ostate = 0;
|
|
int iss = 0;
|
|
u_long tiwin;
|
|
struct tcp_opt_info opti;
|
|
int off, iphlen;
|
|
va_list ap;
|
|
int af; /* af on the wire */
|
|
struct mbuf *tcp_saveti = NULL;
|
|
|
|
va_start(ap, m);
|
|
toff = va_arg(ap, int);
|
|
proto = va_arg(ap, int);
|
|
va_end(ap);
|
|
|
|
tcpstat.tcps_rcvtotal++;
|
|
|
|
bzero(&opti, sizeof(opti));
|
|
opti.ts_present = 0;
|
|
opti.maxseg = 0;
|
|
|
|
/*
|
|
* Get IP and TCP header together in first mbuf.
|
|
* Note: IP leaves IP header in first mbuf.
|
|
*/
|
|
ip = mtod(m, struct ip *);
|
|
#ifdef INET6
|
|
ip6 = NULL;
|
|
#endif
|
|
switch (ip->ip_v) {
|
|
case 4:
|
|
af = AF_INET;
|
|
iphlen = sizeof(struct ip);
|
|
/* would like to get rid of this... */
|
|
if (toff > sizeof (struct ip)) {
|
|
ip_stripoptions(m, (struct mbuf *)0);
|
|
toff = sizeof(struct ip);
|
|
}
|
|
if (m->m_len < toff + sizeof (struct tcphdr)) {
|
|
if ((m = m_pullup(m, toff + sizeof (struct tcphdr))) == 0) {
|
|
tcpstat.tcps_rcvshort++;
|
|
return;
|
|
}
|
|
}
|
|
ip = mtod(m, struct ip *);
|
|
th = (struct tcphdr *)(mtod(m, caddr_t) + toff);
|
|
|
|
/*
|
|
* Checksum extended TCP header and data.
|
|
*/
|
|
len = ip->ip_len;
|
|
tlen = len - toff;
|
|
{
|
|
struct ipovly *ipov;
|
|
ipov = (struct ipovly *)ip;
|
|
bzero(ipov->ih_x1, sizeof ipov->ih_x1);
|
|
ipov->ih_len = htons(tlen);
|
|
}
|
|
if (in_cksum(m, len) != 0) {
|
|
tcpstat.tcps_rcvbadsum++;
|
|
goto drop;
|
|
}
|
|
break;
|
|
#ifdef INET6
|
|
case 6:
|
|
ip = NULL;
|
|
iphlen = sizeof(struct ip6_hdr);
|
|
af = AF_INET6;
|
|
if (m->m_len < toff + sizeof(struct tcphdr)) {
|
|
m = m_pullup(m, toff + sizeof(struct tcphdr)); /*XXX*/
|
|
if (m == NULL) {
|
|
tcpstat.tcps_rcvshort++;
|
|
return;
|
|
}
|
|
}
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
th = (struct tcphdr *)(mtod(m, caddr_t) + toff);
|
|
|
|
/*
|
|
* Checksum extended TCP header and data.
|
|
*/
|
|
len = m->m_pkthdr.len;
|
|
tlen = len - toff;
|
|
if (in6_cksum(m, IPPROTO_TCP, toff, tlen)) {
|
|
tcpstat.tcps_rcvbadsum++;
|
|
goto drop;
|
|
}
|
|
break;
|
|
#endif
|
|
default:
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check that TCP offset makes sense,
|
|
* pull out TCP options and adjust length. XXX
|
|
*/
|
|
off = th->th_off << 2;
|
|
if (off < sizeof (struct tcphdr) || off > tlen) {
|
|
tcpstat.tcps_rcvbadoff++;
|
|
goto drop;
|
|
}
|
|
tlen -= off;
|
|
|
|
/*
|
|
* tcp_input() has been modified to use tlen to mean the TCP data
|
|
* length throughout the function. Other functions can use
|
|
* m->m_pkthdr.len as the basis for calculating the TCP data length.
|
|
* rja
|
|
*/
|
|
|
|
if (off > sizeof (struct tcphdr)) {
|
|
if (m->m_len < toff + off) {
|
|
if ((m = m_pullup(m, toff + off)) == 0) {
|
|
tcpstat.tcps_rcvshort++;
|
|
return;
|
|
}
|
|
switch (af) {
|
|
case AF_INET:
|
|
ip = mtod(m, struct ip *);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
break;
|
|
#endif
|
|
}
|
|
th = (struct tcphdr *)(mtod(m, caddr_t) + toff);
|
|
}
|
|
optlen = off - sizeof (struct tcphdr);
|
|
optp = mtod(m, caddr_t) + toff + sizeof (struct tcphdr);
|
|
/*
|
|
* Do quick retrieval of timestamp options ("options
|
|
* prediction?"). If timestamp is the only option and it's
|
|
* formatted as recommended in RFC 1323 appendix A, we
|
|
* quickly get the values now and not bother calling
|
|
* tcp_dooptions(), etc.
|
|
*/
|
|
if ((optlen == TCPOLEN_TSTAMP_APPA ||
|
|
(optlen > TCPOLEN_TSTAMP_APPA &&
|
|
optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) &&
|
|
*(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) &&
|
|
(th->th_flags & TH_SYN) == 0) {
|
|
opti.ts_present = 1;
|
|
opti.ts_val = ntohl(*(u_int32_t *)(optp + 4));
|
|
opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8));
|
|
optp = NULL; /* we've parsed the options */
|
|
}
|
|
}
|
|
tiflags = th->th_flags;
|
|
|
|
/*
|
|
* Convert TCP protocol specific fields to host format.
|
|
*/
|
|
NTOHL(th->th_seq);
|
|
NTOHL(th->th_ack);
|
|
NTOHS(th->th_win);
|
|
NTOHS(th->th_urp);
|
|
|
|
/*
|
|
* Locate pcb for segment.
|
|
*/
|
|
findpcb:
|
|
inp = NULL;
|
|
#ifdef INET6
|
|
in6p = NULL;
|
|
#endif
|
|
switch (af) {
|
|
case AF_INET:
|
|
inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport,
|
|
ip->ip_dst, th->th_dport);
|
|
if (inp == 0) {
|
|
++tcpstat.tcps_pcbhashmiss;
|
|
inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport);
|
|
}
|
|
#if defined(INET6) && !defined(TCP6)
|
|
if (inp == 0) {
|
|
struct in6_addr s, d;
|
|
|
|
/* mapped addr case */
|
|
bzero(&s, sizeof(s));
|
|
s.s6_addr16[5] = htons(0xffff);
|
|
bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src));
|
|
bzero(&d, sizeof(d));
|
|
d.s6_addr16[5] = htons(0xffff);
|
|
bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst));
|
|
in6p = in6_pcblookup_connect(&tcb6, &s, th->th_sport,
|
|
&d, th->th_dport, 0);
|
|
if (in6p == 0) {
|
|
++tcpstat.tcps_pcbhashmiss;
|
|
in6p = in6_pcblookup_bind(&tcb6, &d,
|
|
th->th_dport, 0);
|
|
}
|
|
}
|
|
#endif
|
|
#ifndef INET6
|
|
if (inp == 0)
|
|
#else
|
|
if (inp == 0 && in6p == 0)
|
|
#endif
|
|
{
|
|
++tcpstat.tcps_noport;
|
|
if (tcp_log_refused && (tiflags & TH_SYN)) {
|
|
#ifndef INET6
|
|
char src[4*sizeof "123"];
|
|
char dst[4*sizeof "123"];
|
|
#else
|
|
char src[INET6_ADDRSTRLEN];
|
|
char dst[INET6_ADDRSTRLEN];
|
|
#endif
|
|
if (ip) {
|
|
strcpy(src, inet_ntoa(ip->ip_dst));
|
|
strcpy(dst, inet_ntoa(ip->ip_dst));
|
|
}
|
|
#ifdef INET6
|
|
else if (ip6) {
|
|
strcpy(src, ip6_sprintf(&ip6->ip6_dst));
|
|
strcpy(dst, ip6_sprintf(&ip6->ip6_src));
|
|
}
|
|
#endif
|
|
else {
|
|
strcpy(src, "(unknown)");
|
|
strcpy(dst, "(unknown)");
|
|
}
|
|
log(LOG_INFO,
|
|
"Connection attempt to TCP %s:%d from %s:%d\n",
|
|
src, ntohs(th->th_dport),
|
|
dst, ntohs(th->th_sport));
|
|
}
|
|
goto dropwithreset;
|
|
}
|
|
#ifdef IPSEC
|
|
if (inp && ipsec4_in_reject(m, inp)) {
|
|
ipsecstat.in_polvio++;
|
|
goto drop;
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p && ipsec4_in_reject_so(m, in6p->in6p_socket)) {
|
|
ipsecstat.in_polvio++;
|
|
goto drop;
|
|
}
|
|
#endif
|
|
#endif /*IPSEC*/
|
|
break;
|
|
#if defined(INET6) && !defined(TCP6)
|
|
case AF_INET6:
|
|
{
|
|
int faith;
|
|
|
|
#if defined(NFAITH) && NFAITH > 0
|
|
if (m->m_pkthdr.rcvif
|
|
&& m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
|
|
faith = 1;
|
|
} else
|
|
faith = 0;
|
|
#else
|
|
faith = 0;
|
|
#endif
|
|
in6p = in6_pcblookup_connect(&tcb6, &ip6->ip6_src, th->th_sport,
|
|
&ip6->ip6_dst, th->th_dport, faith);
|
|
if (in6p == NULL) {
|
|
++tcpstat.tcps_pcbhashmiss;
|
|
in6p = in6_pcblookup_bind(&tcb6, &ip6->ip6_dst,
|
|
th->th_dport, faith);
|
|
}
|
|
if (in6p == NULL) {
|
|
++tcpstat.tcps_noport;
|
|
goto dropwithreset;
|
|
}
|
|
#ifdef IPSEC
|
|
if (ipsec6_in_reject(m, in6p)) {
|
|
ipsec6stat.in_polvio++;
|
|
goto drop;
|
|
}
|
|
#endif /*IPSEC*/
|
|
break;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* If the state is CLOSED (i.e., TCB does not exist) then
|
|
* all data in the incoming segment is discarded.
|
|
* If the TCB exists but is in CLOSED state, it is embryonic,
|
|
* but should either do a listen or a connect soon.
|
|
*/
|
|
tp = NULL;
|
|
so = NULL;
|
|
if (inp) {
|
|
tp = intotcpcb(inp);
|
|
so = inp->inp_socket;
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p) {
|
|
tp = in6totcpcb(in6p);
|
|
so = in6p->in6p_socket;
|
|
}
|
|
#endif
|
|
if (tp == 0) {
|
|
goto dropwithreset;
|
|
}
|
|
if (tp->t_state == TCPS_CLOSED)
|
|
goto drop;
|
|
|
|
/* Unscale the window into a 32-bit value. */
|
|
if ((tiflags & TH_SYN) == 0)
|
|
tiwin = th->th_win << tp->snd_scale;
|
|
else
|
|
tiwin = th->th_win;
|
|
|
|
#ifdef INET6
|
|
/* save packet options if user wanted */
|
|
if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) {
|
|
if (in6p->in6p_options) {
|
|
m_freem(in6p->in6p_options);
|
|
in6p->in6p_options = 0;
|
|
}
|
|
ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m);
|
|
}
|
|
#endif
|
|
|
|
if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) {
|
|
union syn_cache_sa src;
|
|
union syn_cache_sa dst;
|
|
|
|
bzero(&src, sizeof(src));
|
|
bzero(&dst, sizeof(dst));
|
|
switch (af) {
|
|
case AF_INET:
|
|
src.sin.sin_len = sizeof(struct sockaddr_in);
|
|
src.sin.sin_family = AF_INET;
|
|
src.sin.sin_addr = ip->ip_src;
|
|
src.sin.sin_port = th->th_sport;
|
|
|
|
dst.sin.sin_len = sizeof(struct sockaddr_in);
|
|
dst.sin.sin_family = AF_INET;
|
|
dst.sin.sin_addr = ip->ip_dst;
|
|
dst.sin.sin_port = th->th_dport;
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
src.sin6.sin6_len = sizeof(struct sockaddr_in6);
|
|
src.sin6.sin6_family = AF_INET6;
|
|
src.sin6.sin6_addr = ip6->ip6_src;
|
|
src.sin6.sin6_port = th->th_sport;
|
|
|
|
dst.sin6.sin6_len = sizeof(struct sockaddr_in6);
|
|
dst.sin6.sin6_family = AF_INET6;
|
|
dst.sin6.sin6_addr = ip6->ip6_dst;
|
|
dst.sin6.sin6_port = th->th_dport;
|
|
break;
|
|
#endif /* INET6 */
|
|
default:
|
|
goto badsyn; /*sanity*/
|
|
}
|
|
|
|
if (so->so_options & SO_DEBUG) {
|
|
ostate = tp->t_state;
|
|
tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT);
|
|
if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) {
|
|
m_freem(tcp_saveti);
|
|
tcp_saveti = NULL;
|
|
} else {
|
|
tcp_saveti->m_len += sizeof(struct tcphdr);
|
|
bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen,
|
|
sizeof(struct tcphdr));
|
|
}
|
|
if (tcp_saveti) {
|
|
/*
|
|
* need to recover version # field, which was
|
|
* overwritten on ip_cksum computation.
|
|
*/
|
|
struct ip *sip;
|
|
sip = mtod(tcp_saveti, struct ip *);
|
|
switch (af) {
|
|
case AF_INET:
|
|
sip->ip_v = 4;
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
sip->ip_v = 6;
|
|
break;
|
|
#endif
|
|
}
|
|
}
|
|
}
|
|
if (so->so_options & SO_ACCEPTCONN) {
|
|
if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) {
|
|
if (tiflags & TH_RST) {
|
|
syn_cache_reset(&src.sa, &dst.sa, th);
|
|
} else if ((tiflags & (TH_ACK|TH_SYN)) ==
|
|
(TH_ACK|TH_SYN)) {
|
|
/*
|
|
* Received a SYN,ACK. This should
|
|
* never happen while we are in
|
|
* LISTEN. Send an RST.
|
|
*/
|
|
goto badsyn;
|
|
} else if (tiflags & TH_ACK) {
|
|
so = syn_cache_get(&src.sa, &dst.sa,
|
|
th, toff, tlen, so, m);
|
|
if (so == NULL) {
|
|
/*
|
|
* We don't have a SYN for
|
|
* this ACK; send an RST.
|
|
*/
|
|
goto badsyn;
|
|
} else if (so ==
|
|
(struct socket *)(-1)) {
|
|
/*
|
|
* We were unable to create
|
|
* the connection. If the
|
|
* 3-way handshake was
|
|
* completed, and RST has
|
|
* been sent to the peer.
|
|
* Since the mbuf might be
|
|
* in use for the reply,
|
|
* do not free it.
|
|
*/
|
|
m = NULL;
|
|
} else {
|
|
/*
|
|
* We have created a
|
|
* full-blown connection.
|
|
*/
|
|
tp = NULL;
|
|
inp = NULL;
|
|
#ifdef INET6
|
|
in6p = NULL;
|
|
#endif
|
|
switch (so->so_proto->pr_domain->dom_family) {
|
|
case AF_INET:
|
|
inp = sotoinpcb(so);
|
|
tp = intotcpcb(inp);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
in6p = sotoin6pcb(so);
|
|
tp = in6totcpcb(in6p);
|
|
break;
|
|
#endif
|
|
}
|
|
if (tp == NULL)
|
|
goto badsyn; /*XXX*/
|
|
tiwin <<= tp->snd_scale;
|
|
goto after_listen;
|
|
}
|
|
} else {
|
|
/*
|
|
* None of RST, SYN or ACK was set.
|
|
* This is an invalid packet for a
|
|
* TCB in LISTEN state. Send a RST.
|
|
*/
|
|
goto badsyn;
|
|
}
|
|
} else {
|
|
/*
|
|
* Received a SYN.
|
|
*/
|
|
|
|
/*
|
|
* LISTEN socket received a SYN
|
|
* from itself? This can't possibly
|
|
* be valid; drop the packet.
|
|
*/
|
|
if (th->th_sport == th->th_dport) {
|
|
int i;
|
|
|
|
switch (af) {
|
|
case AF_INET:
|
|
i = in_hosteq(ip->ip_src, ip->ip_dst);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst);
|
|
break;
|
|
#endif
|
|
default:
|
|
i = 1;
|
|
}
|
|
if (i) {
|
|
tcpstat.tcps_badsyn++;
|
|
goto drop;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* SYN looks ok; create compressed TCP
|
|
* state for it.
|
|
*/
|
|
if (so->so_qlen <= so->so_qlimit &&
|
|
syn_cache_add(&src.sa, &dst.sa, th, tlen,
|
|
so, m, optp, optlen, &opti))
|
|
m = NULL;
|
|
}
|
|
goto drop;
|
|
}
|
|
}
|
|
|
|
after_listen:
|
|
#ifdef DIAGNOSTIC
|
|
/*
|
|
* Should not happen now that all embryonic connections
|
|
* are handled with compressed state.
|
|
*/
|
|
if (tp->t_state == TCPS_LISTEN)
|
|
panic("tcp_input: TCPS_LISTEN");
|
|
#endif
|
|
|
|
/*
|
|
* Segment received on connection.
|
|
* Reset idle time and keep-alive timer.
|
|
*/
|
|
tp->t_idle = 0;
|
|
if (TCPS_HAVEESTABLISHED(tp->t_state))
|
|
TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle);
|
|
|
|
/*
|
|
* Process options.
|
|
*/
|
|
if (optp)
|
|
tcp_dooptions(tp, optp, optlen, th, &opti);
|
|
|
|
/*
|
|
* Header prediction: check for the two common cases
|
|
* of a uni-directional data xfer. If the packet has
|
|
* no control flags, is in-sequence, the window didn't
|
|
* change and we're not retransmitting, it's a
|
|
* candidate. If the length is zero and the ack moved
|
|
* forward, we're the sender side of the xfer. Just
|
|
* free the data acked & wake any higher level process
|
|
* that was blocked waiting for space. If the length
|
|
* is non-zero and the ack didn't move, we're the
|
|
* receiver side. If we're getting packets in-order
|
|
* (the reassembly queue is empty), add the data to
|
|
* the socket buffer and note that we need a delayed ack.
|
|
*/
|
|
if (tp->t_state == TCPS_ESTABLISHED &&
|
|
(tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
|
|
(!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) &&
|
|
th->th_seq == tp->rcv_nxt &&
|
|
tiwin && tiwin == tp->snd_wnd &&
|
|
tp->snd_nxt == tp->snd_max) {
|
|
|
|
/*
|
|
* If last ACK falls within this segment's sequence numbers,
|
|
* record the timestamp.
|
|
*/
|
|
if (opti.ts_present &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
|
|
SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) {
|
|
tp->ts_recent_age = tcp_now;
|
|
tp->ts_recent = opti.ts_val;
|
|
}
|
|
|
|
if (tlen == 0) {
|
|
if (SEQ_GT(th->th_ack, tp->snd_una) &&
|
|
SEQ_LEQ(th->th_ack, tp->snd_max) &&
|
|
tp->snd_cwnd >= tp->snd_wnd &&
|
|
tp->t_dupacks < tcprexmtthresh) {
|
|
/*
|
|
* this is a pure ack for outstanding data.
|
|
*/
|
|
++tcpstat.tcps_predack;
|
|
if (opti.ts_present)
|
|
tcp_xmit_timer(tp,
|
|
tcp_now-opti.ts_ecr+1);
|
|
else if (tp->t_rtt &&
|
|
SEQ_GT(th->th_ack, tp->t_rtseq))
|
|
tcp_xmit_timer(tp, tp->t_rtt);
|
|
acked = th->th_ack - tp->snd_una;
|
|
tcpstat.tcps_rcvackpack++;
|
|
tcpstat.tcps_rcvackbyte += acked;
|
|
sbdrop(&so->so_snd, acked);
|
|
tp->snd_una = th->th_ack;
|
|
m_freem(m);
|
|
|
|
/*
|
|
* If all outstanding data are acked, stop
|
|
* retransmit timer, otherwise restart timer
|
|
* using current (possibly backed-off) value.
|
|
* If process is waiting for space,
|
|
* wakeup/selwakeup/signal. If data
|
|
* are ready to send, let tcp_output
|
|
* decide between more output or persist.
|
|
*/
|
|
if (tp->snd_una == tp->snd_max)
|
|
TCP_TIMER_DISARM(tp, TCPT_REXMT);
|
|
else if (TCP_TIMER_ISARMED(tp,
|
|
TCPT_PERSIST) == 0)
|
|
TCP_TIMER_ARM(tp, TCPT_REXMT,
|
|
tp->t_rxtcur);
|
|
|
|
sowwakeup(so);
|
|
if (so->so_snd.sb_cc)
|
|
(void) tcp_output(tp);
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
}
|
|
} else if (th->th_ack == tp->snd_una &&
|
|
tp->segq.lh_first == NULL &&
|
|
tlen <= sbspace(&so->so_rcv)) {
|
|
/*
|
|
* this is a pure, in-sequence data packet
|
|
* with nothing on the reassembly queue and
|
|
* we have enough buffer space to take it.
|
|
*/
|
|
++tcpstat.tcps_preddat;
|
|
tp->rcv_nxt += tlen;
|
|
tcpstat.tcps_rcvpack++;
|
|
tcpstat.tcps_rcvbyte += tlen;
|
|
/*
|
|
* Drop TCP, IP headers and TCP options then add data
|
|
* to socket buffer.
|
|
*/
|
|
m->m_data += toff + off;
|
|
m->m_len -= (toff + off);
|
|
sbappend(&so->so_rcv, m);
|
|
sorwakeup(so);
|
|
TCP_SETUP_ACK(tp, th);
|
|
if (tp->t_flags & TF_ACKNOW)
|
|
(void) tcp_output(tp);
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Drop TCP, IP headers and TCP options.
|
|
*/
|
|
hdroptlen = toff + off;
|
|
m->m_data += hdroptlen;
|
|
m->m_len -= hdroptlen;
|
|
|
|
/*
|
|
* Calculate amount of space in receive window,
|
|
* and then do TCP input processing.
|
|
* Receive window is amount of space in rcv queue,
|
|
* but not less than advertised window.
|
|
*/
|
|
{ int win;
|
|
|
|
win = sbspace(&so->so_rcv);
|
|
if (win < 0)
|
|
win = 0;
|
|
tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt));
|
|
}
|
|
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* If the state is SYN_SENT:
|
|
* if seg contains an ACK, but not for our SYN, drop the input.
|
|
* if seg contains a RST, then drop the connection.
|
|
* if seg does not contain SYN, then drop it.
|
|
* Otherwise this is an acceptable SYN segment
|
|
* initialize tp->rcv_nxt and tp->irs
|
|
* if seg contains ack then advance tp->snd_una
|
|
* if SYN has been acked change to ESTABLISHED else SYN_RCVD state
|
|
* arrange for segment to be acked (eventually)
|
|
* continue processing rest of data/controls, beginning with URG
|
|
*/
|
|
case TCPS_SYN_SENT:
|
|
if ((tiflags & TH_ACK) &&
|
|
(SEQ_LEQ(th->th_ack, tp->iss) ||
|
|
SEQ_GT(th->th_ack, tp->snd_max)))
|
|
goto dropwithreset;
|
|
if (tiflags & TH_RST) {
|
|
if (tiflags & TH_ACK)
|
|
tp = tcp_drop(tp, ECONNREFUSED);
|
|
goto drop;
|
|
}
|
|
if ((tiflags & TH_SYN) == 0)
|
|
goto drop;
|
|
if (tiflags & TH_ACK) {
|
|
tp->snd_una = th->th_ack;
|
|
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
|
tp->snd_nxt = tp->snd_una;
|
|
}
|
|
TCP_TIMER_DISARM(tp, TCPT_REXMT);
|
|
tp->irs = th->th_seq;
|
|
tcp_rcvseqinit(tp);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tcp_mss_from_peer(tp, opti.maxseg);
|
|
|
|
/*
|
|
* Initialize the initial congestion window. If we
|
|
* had to retransmit the SYN, we must initialize cwnd
|
|
* to 1 segment (i.e. the Loss Window).
|
|
*/
|
|
if (tp->t_flags & TF_SYN_REXMT)
|
|
tp->snd_cwnd = tp->t_peermss;
|
|
else
|
|
tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win,
|
|
tp->t_peermss);
|
|
|
|
tcp_rmx_rtt(tp);
|
|
if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
|
|
tcpstat.tcps_connects++;
|
|
soisconnected(so);
|
|
tcp_established(tp);
|
|
/* Do window scaling on this connection? */
|
|
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
|
|
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
|
|
tp->snd_scale = tp->requested_s_scale;
|
|
tp->rcv_scale = tp->request_r_scale;
|
|
}
|
|
TCP_REASS_LOCK(tp);
|
|
(void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen);
|
|
TCP_REASS_UNLOCK(tp);
|
|
/*
|
|
* if we didn't have to retransmit the SYN,
|
|
* use its rtt as our initial srtt & rtt var.
|
|
*/
|
|
if (tp->t_rtt)
|
|
tcp_xmit_timer(tp, tp->t_rtt);
|
|
} else
|
|
tp->t_state = TCPS_SYN_RECEIVED;
|
|
|
|
/*
|
|
* Advance th->th_seq to correspond to first data byte.
|
|
* If data, trim to stay within window,
|
|
* dropping FIN if necessary.
|
|
*/
|
|
th->th_seq++;
|
|
if (tlen > tp->rcv_wnd) {
|
|
todrop = tlen - tp->rcv_wnd;
|
|
m_adj(m, -todrop);
|
|
tlen = tp->rcv_wnd;
|
|
tiflags &= ~TH_FIN;
|
|
tcpstat.tcps_rcvpackafterwin++;
|
|
tcpstat.tcps_rcvbyteafterwin += todrop;
|
|
}
|
|
tp->snd_wl1 = th->th_seq - 1;
|
|
tp->rcv_up = th->th_seq;
|
|
goto step6;
|
|
|
|
/*
|
|
* If the state is SYN_RECEIVED:
|
|
* If seg contains an ACK, but not for our SYN, drop the input
|
|
* and generate an RST. See page 36, rfc793
|
|
*/
|
|
case TCPS_SYN_RECEIVED:
|
|
if ((tiflags & TH_ACK) &&
|
|
(SEQ_LEQ(th->th_ack, tp->iss) ||
|
|
SEQ_GT(th->th_ack, tp->snd_max)))
|
|
goto dropwithreset;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* States other than LISTEN or SYN_SENT.
|
|
* First check timestamp, if present.
|
|
* Then check that at least some bytes of segment are within
|
|
* receive window. If segment begins before rcv_nxt,
|
|
* drop leading data (and SYN); if nothing left, just ack.
|
|
*
|
|
* RFC 1323 PAWS: If we have a timestamp reply on this segment
|
|
* and it's less than ts_recent, drop it.
|
|
*/
|
|
if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent &&
|
|
TSTMP_LT(opti.ts_val, tp->ts_recent)) {
|
|
|
|
/* Check to see if ts_recent is over 24 days old. */
|
|
if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) {
|
|
/*
|
|
* Invalidate ts_recent. If this segment updates
|
|
* ts_recent, the age will be reset later and ts_recent
|
|
* will get a valid value. If it does not, setting
|
|
* ts_recent to zero will at least satisfy the
|
|
* requirement that zero be placed in the timestamp
|
|
* echo reply when ts_recent isn't valid. The
|
|
* age isn't reset until we get a valid ts_recent
|
|
* because we don't want out-of-order segments to be
|
|
* dropped when ts_recent is old.
|
|
*/
|
|
tp->ts_recent = 0;
|
|
} else {
|
|
tcpstat.tcps_rcvduppack++;
|
|
tcpstat.tcps_rcvdupbyte += tlen;
|
|
tcpstat.tcps_pawsdrop++;
|
|
goto dropafterack;
|
|
}
|
|
}
|
|
|
|
todrop = tp->rcv_nxt - th->th_seq;
|
|
if (todrop > 0) {
|
|
if (tiflags & TH_SYN) {
|
|
tiflags &= ~TH_SYN;
|
|
th->th_seq++;
|
|
if (th->th_urp > 1)
|
|
th->th_urp--;
|
|
else {
|
|
tiflags &= ~TH_URG;
|
|
th->th_urp = 0;
|
|
}
|
|
todrop--;
|
|
}
|
|
if (todrop > tlen ||
|
|
(todrop == tlen && (tiflags & TH_FIN) == 0)) {
|
|
/*
|
|
* Any valid FIN must be to the left of the window.
|
|
* At this point the FIN must be a duplicate or
|
|
* out of sequence; drop it.
|
|
*/
|
|
tiflags &= ~TH_FIN;
|
|
/*
|
|
* Send an ACK to resynchronize and drop any data.
|
|
* But keep on processing for RST or ACK.
|
|
*/
|
|
tp->t_flags |= TF_ACKNOW;
|
|
todrop = tlen;
|
|
tcpstat.tcps_rcvdupbyte += todrop;
|
|
tcpstat.tcps_rcvduppack++;
|
|
} else {
|
|
tcpstat.tcps_rcvpartduppack++;
|
|
tcpstat.tcps_rcvpartdupbyte += todrop;
|
|
}
|
|
m_adj(m, todrop);
|
|
th->th_seq += todrop;
|
|
tlen -= todrop;
|
|
if (th->th_urp > todrop)
|
|
th->th_urp -= todrop;
|
|
else {
|
|
tiflags &= ~TH_URG;
|
|
th->th_urp = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If new data are received on a connection after the
|
|
* user processes are gone, then RST the other end.
|
|
*/
|
|
if ((so->so_state & SS_NOFDREF) &&
|
|
tp->t_state > TCPS_CLOSE_WAIT && tlen) {
|
|
tp = tcp_close(tp);
|
|
tcpstat.tcps_rcvafterclose++;
|
|
goto dropwithreset;
|
|
}
|
|
|
|
/*
|
|
* If segment ends after window, drop trailing data
|
|
* (and PUSH and FIN); if nothing left, just ACK.
|
|
*/
|
|
todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd);
|
|
if (todrop > 0) {
|
|
tcpstat.tcps_rcvpackafterwin++;
|
|
if (todrop >= tlen) {
|
|
tcpstat.tcps_rcvbyteafterwin += tlen;
|
|
/*
|
|
* If a new connection request is received
|
|
* while in TIME_WAIT, drop the old connection
|
|
* and start over if the sequence numbers
|
|
* are above the previous ones.
|
|
*/
|
|
if (tiflags & TH_SYN &&
|
|
tp->t_state == TCPS_TIME_WAIT &&
|
|
SEQ_GT(th->th_seq, tp->rcv_nxt)) {
|
|
iss = tcp_new_iss(tp, sizeof(struct tcpcb),
|
|
tp->snd_nxt);
|
|
tp = tcp_close(tp);
|
|
/*
|
|
* We have already advanced the mbuf
|
|
* pointers past the IP+TCP headers and
|
|
* options. Restore those pointers before
|
|
* attempting to use the TCP header again.
|
|
*/
|
|
m->m_data -= hdroptlen;
|
|
m->m_len += hdroptlen;
|
|
hdroptlen = 0;
|
|
goto findpcb;
|
|
}
|
|
/*
|
|
* If window is closed can only take segments at
|
|
* window edge, and have to drop data and PUSH from
|
|
* incoming segments. Continue processing, but
|
|
* remember to ack. Otherwise, drop segment
|
|
* and ack.
|
|
*/
|
|
if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tcpstat.tcps_rcvwinprobe++;
|
|
} else
|
|
goto dropafterack;
|
|
} else
|
|
tcpstat.tcps_rcvbyteafterwin += todrop;
|
|
m_adj(m, -todrop);
|
|
tlen -= todrop;
|
|
tiflags &= ~(TH_PUSH|TH_FIN);
|
|
}
|
|
|
|
/*
|
|
* If last ACK falls within this segment's sequence numbers,
|
|
* and the timestamp is newer, record it.
|
|
*/
|
|
if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
|
|
SEQ_LT(tp->last_ack_sent, th->th_seq + tlen +
|
|
((tiflags & (TH_SYN|TH_FIN)) != 0))) {
|
|
tp->ts_recent_age = tcp_now;
|
|
tp->ts_recent = opti.ts_val;
|
|
}
|
|
|
|
/*
|
|
* If the RST bit is set examine the state:
|
|
* SYN_RECEIVED STATE:
|
|
* If passive open, return to LISTEN state.
|
|
* If active open, inform user that connection was refused.
|
|
* ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
|
|
* Inform user that connection was reset, and close tcb.
|
|
* CLOSING, LAST_ACK, TIME_WAIT STATES
|
|
* Close the tcb.
|
|
*/
|
|
if (tiflags&TH_RST) switch (tp->t_state) {
|
|
|
|
case TCPS_SYN_RECEIVED:
|
|
so->so_error = ECONNREFUSED;
|
|
goto close;
|
|
|
|
case TCPS_ESTABLISHED:
|
|
case TCPS_FIN_WAIT_1:
|
|
case TCPS_FIN_WAIT_2:
|
|
case TCPS_CLOSE_WAIT:
|
|
so->so_error = ECONNRESET;
|
|
close:
|
|
tp->t_state = TCPS_CLOSED;
|
|
tcpstat.tcps_drops++;
|
|
tp = tcp_close(tp);
|
|
goto drop;
|
|
|
|
case TCPS_CLOSING:
|
|
case TCPS_LAST_ACK:
|
|
case TCPS_TIME_WAIT:
|
|
tp = tcp_close(tp);
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* If a SYN is in the window, then this is an
|
|
* error and we send an RST and drop the connection.
|
|
*/
|
|
if (tiflags & TH_SYN) {
|
|
tp = tcp_drop(tp, ECONNRESET);
|
|
goto dropwithreset;
|
|
}
|
|
|
|
/*
|
|
* If the ACK bit is off we drop the segment and return.
|
|
*/
|
|
if ((tiflags & TH_ACK) == 0) {
|
|
if (tp->t_flags & TF_ACKNOW)
|
|
goto dropafterack;
|
|
else
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* Ack processing.
|
|
*/
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* In SYN_RECEIVED state if the ack ACKs our SYN then enter
|
|
* ESTABLISHED state and continue processing, otherwise
|
|
* send an RST.
|
|
*/
|
|
case TCPS_SYN_RECEIVED:
|
|
if (SEQ_GT(tp->snd_una, th->th_ack) ||
|
|
SEQ_GT(th->th_ack, tp->snd_max))
|
|
goto dropwithreset;
|
|
tcpstat.tcps_connects++;
|
|
soisconnected(so);
|
|
tcp_established(tp);
|
|
/* Do window scaling? */
|
|
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
|
|
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
|
|
tp->snd_scale = tp->requested_s_scale;
|
|
tp->rcv_scale = tp->request_r_scale;
|
|
}
|
|
TCP_REASS_LOCK(tp);
|
|
(void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen);
|
|
TCP_REASS_UNLOCK(tp);
|
|
tp->snd_wl1 = th->th_seq - 1;
|
|
/* fall into ... */
|
|
|
|
/*
|
|
* In ESTABLISHED state: drop duplicate ACKs; ACK out of range
|
|
* ACKs. If the ack is in the range
|
|
* tp->snd_una < th->th_ack <= tp->snd_max
|
|
* then advance tp->snd_una to th->th_ack and drop
|
|
* data from the retransmission queue. If this ACK reflects
|
|
* more up to date window information we update our window information.
|
|
*/
|
|
case TCPS_ESTABLISHED:
|
|
case TCPS_FIN_WAIT_1:
|
|
case TCPS_FIN_WAIT_2:
|
|
case TCPS_CLOSE_WAIT:
|
|
case TCPS_CLOSING:
|
|
case TCPS_LAST_ACK:
|
|
case TCPS_TIME_WAIT:
|
|
|
|
if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
|
|
if (tlen == 0 && tiwin == tp->snd_wnd) {
|
|
tcpstat.tcps_rcvdupack++;
|
|
/*
|
|
* If we have outstanding data (other than
|
|
* a window probe), this is a completely
|
|
* duplicate ack (ie, window info didn't
|
|
* change), the ack is the biggest we've
|
|
* seen and we've seen exactly our rexmt
|
|
* threshhold of them, assume a packet
|
|
* has been dropped and retransmit it.
|
|
* Kludge snd_nxt & the congestion
|
|
* window so we send only this one
|
|
* packet.
|
|
*
|
|
* We know we're losing at the current
|
|
* window size so do congestion avoidance
|
|
* (set ssthresh to half the current window
|
|
* and pull our congestion window back to
|
|
* the new ssthresh).
|
|
*
|
|
* Dup acks mean that packets have left the
|
|
* network (they're now cached at the receiver)
|
|
* so bump cwnd by the amount in the receiver
|
|
* to keep a constant cwnd packets in the
|
|
* network.
|
|
*/
|
|
if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 ||
|
|
th->th_ack != tp->snd_una)
|
|
tp->t_dupacks = 0;
|
|
else if (++tp->t_dupacks == tcprexmtthresh) {
|
|
tcp_seq onxt = tp->snd_nxt;
|
|
u_int win =
|
|
min(tp->snd_wnd, tp->snd_cwnd) /
|
|
2 / tp->t_segsz;
|
|
if (SEQ_LT(th->th_ack, tp->snd_recover)) {
|
|
/*
|
|
* False fast retransmit after
|
|
* timeout. Do not cut window.
|
|
*/
|
|
tp->snd_cwnd += tp->t_segsz;
|
|
tp->t_dupacks = 0;
|
|
(void) tcp_output(tp);
|
|
goto drop;
|
|
}
|
|
|
|
if (win < 2)
|
|
win = 2;
|
|
tp->snd_ssthresh = win * tp->t_segsz;
|
|
tp->snd_recover = tp->snd_max;
|
|
TCP_TIMER_DISARM(tp, TCPT_REXMT);
|
|
tp->t_rtt = 0;
|
|
tp->snd_nxt = th->th_ack;
|
|
tp->snd_cwnd = tp->t_segsz;
|
|
(void) tcp_output(tp);
|
|
tp->snd_cwnd = tp->snd_ssthresh +
|
|
tp->t_segsz * tp->t_dupacks;
|
|
if (SEQ_GT(onxt, tp->snd_nxt))
|
|
tp->snd_nxt = onxt;
|
|
goto drop;
|
|
} else if (tp->t_dupacks > tcprexmtthresh) {
|
|
tp->snd_cwnd += tp->t_segsz;
|
|
(void) tcp_output(tp);
|
|
goto drop;
|
|
}
|
|
} else
|
|
tp->t_dupacks = 0;
|
|
break;
|
|
}
|
|
/*
|
|
* If the congestion window was inflated to account
|
|
* for the other side's cached packets, retract it.
|
|
*/
|
|
if (!tcp_do_newreno) {
|
|
if (tp->t_dupacks >= tcprexmtthresh &&
|
|
tp->snd_cwnd > tp->snd_ssthresh)
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
tp->t_dupacks = 0;
|
|
} else if (tp->t_dupacks >= tcprexmtthresh
|
|
&& !tcp_newreno(tp, th)) {
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
/*
|
|
* Window inflation should have left us with approx.
|
|
* snd_ssthresh outstanding data. But in case we
|
|
* would be inclined to send a burst, better to do
|
|
* it via the slow start mechanism.
|
|
*/
|
|
if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh)
|
|
tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack)
|
|
+ tp->t_segsz;
|
|
tp->t_dupacks = 0;
|
|
}
|
|
if (SEQ_GT(th->th_ack, tp->snd_max)) {
|
|
tcpstat.tcps_rcvacktoomuch++;
|
|
goto dropafterack;
|
|
}
|
|
acked = th->th_ack - tp->snd_una;
|
|
tcpstat.tcps_rcvackpack++;
|
|
tcpstat.tcps_rcvackbyte += acked;
|
|
|
|
/*
|
|
* If we have a timestamp reply, update smoothed
|
|
* round trip time. If no timestamp is present but
|
|
* transmit timer is running and timed sequence
|
|
* number was acked, update smoothed round trip time.
|
|
* Since we now have an rtt measurement, cancel the
|
|
* timer backoff (cf., Phil Karn's retransmit alg.).
|
|
* Recompute the initial retransmit timer.
|
|
*/
|
|
if (opti.ts_present)
|
|
tcp_xmit_timer(tp, tcp_now - opti.ts_ecr + 1);
|
|
else if (tp->t_rtt && SEQ_GT(th->th_ack, tp->t_rtseq))
|
|
tcp_xmit_timer(tp,tp->t_rtt);
|
|
|
|
/*
|
|
* If all outstanding data is acked, stop retransmit
|
|
* timer and remember to restart (more output or persist).
|
|
* If there is more data to be acked, restart retransmit
|
|
* timer, using current (possibly backed-off) value.
|
|
*/
|
|
if (th->th_ack == tp->snd_max) {
|
|
TCP_TIMER_DISARM(tp, TCPT_REXMT);
|
|
needoutput = 1;
|
|
} else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0)
|
|
TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur);
|
|
/*
|
|
* When new data is acked, open the congestion window.
|
|
* If the window gives us less than ssthresh packets
|
|
* in flight, open exponentially (segsz per packet).
|
|
* Otherwise open linearly: segsz per window
|
|
* (segsz^2 / cwnd per packet), plus a constant
|
|
* fraction of a packet (segsz/8) to help larger windows
|
|
* open quickly enough.
|
|
*/
|
|
{
|
|
register u_int cw = tp->snd_cwnd;
|
|
register u_int incr = tp->t_segsz;
|
|
|
|
if (cw > tp->snd_ssthresh)
|
|
incr = incr * incr / cw;
|
|
if (!tcp_do_newreno || SEQ_GEQ(th->th_ack, tp->snd_recover))
|
|
tp->snd_cwnd = min(cw + incr,TCP_MAXWIN<<tp->snd_scale);
|
|
}
|
|
if (acked > so->so_snd.sb_cc) {
|
|
tp->snd_wnd -= so->so_snd.sb_cc;
|
|
sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
|
|
ourfinisacked = 1;
|
|
} else {
|
|
sbdrop(&so->so_snd, acked);
|
|
tp->snd_wnd -= acked;
|
|
ourfinisacked = 0;
|
|
}
|
|
sowwakeup(so);
|
|
tp->snd_una = th->th_ack;
|
|
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
|
tp->snd_nxt = tp->snd_una;
|
|
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* In FIN_WAIT_1 STATE in addition to the processing
|
|
* for the ESTABLISHED state if our FIN is now acknowledged
|
|
* then enter FIN_WAIT_2.
|
|
*/
|
|
case TCPS_FIN_WAIT_1:
|
|
if (ourfinisacked) {
|
|
/*
|
|
* If we can't receive any more
|
|
* data, then closing user can proceed.
|
|
* Starting the timer is contrary to the
|
|
* specification, but if we don't get a FIN
|
|
* we'll hang forever.
|
|
*/
|
|
if (so->so_state & SS_CANTRCVMORE) {
|
|
soisdisconnected(so);
|
|
if (tcp_maxidle > 0)
|
|
TCP_TIMER_ARM(tp, TCPT_2MSL,
|
|
tcp_maxidle);
|
|
}
|
|
tp->t_state = TCPS_FIN_WAIT_2;
|
|
}
|
|
break;
|
|
|
|
/*
|
|
* In CLOSING STATE in addition to the processing for
|
|
* the ESTABLISHED state if the ACK acknowledges our FIN
|
|
* then enter the TIME-WAIT state, otherwise ignore
|
|
* the segment.
|
|
*/
|
|
case TCPS_CLOSING:
|
|
if (ourfinisacked) {
|
|
tp->t_state = TCPS_TIME_WAIT;
|
|
tcp_canceltimers(tp);
|
|
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
|
|
soisdisconnected(so);
|
|
}
|
|
break;
|
|
|
|
/*
|
|
* In LAST_ACK, we may still be waiting for data to drain
|
|
* and/or to be acked, as well as for the ack of our FIN.
|
|
* If our FIN is now acknowledged, delete the TCB,
|
|
* enter the closed state and return.
|
|
*/
|
|
case TCPS_LAST_ACK:
|
|
if (ourfinisacked) {
|
|
tp = tcp_close(tp);
|
|
goto drop;
|
|
}
|
|
break;
|
|
|
|
/*
|
|
* In TIME_WAIT state the only thing that should arrive
|
|
* is a retransmission of the remote FIN. Acknowledge
|
|
* it and restart the finack timer.
|
|
*/
|
|
case TCPS_TIME_WAIT:
|
|
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
|
|
goto dropafterack;
|
|
}
|
|
}
|
|
|
|
step6:
|
|
/*
|
|
* Update window information.
|
|
* Don't look at window if no ACK: TAC's send garbage on first SYN.
|
|
*/
|
|
if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) ||
|
|
(tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) ||
|
|
(tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) {
|
|
/* keep track of pure window updates */
|
|
if (tlen == 0 &&
|
|
tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)
|
|
tcpstat.tcps_rcvwinupd++;
|
|
tp->snd_wnd = tiwin;
|
|
tp->snd_wl1 = th->th_seq;
|
|
tp->snd_wl2 = th->th_ack;
|
|
if (tp->snd_wnd > tp->max_sndwnd)
|
|
tp->max_sndwnd = tp->snd_wnd;
|
|
needoutput = 1;
|
|
}
|
|
|
|
/*
|
|
* Process segments with URG.
|
|
*/
|
|
if ((tiflags & TH_URG) && th->th_urp &&
|
|
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
|
/*
|
|
* This is a kludge, but if we receive and accept
|
|
* random urgent pointers, we'll crash in
|
|
* soreceive. It's hard to imagine someone
|
|
* actually wanting to send this much urgent data.
|
|
*/
|
|
if (th->th_urp + so->so_rcv.sb_cc > sb_max) {
|
|
th->th_urp = 0; /* XXX */
|
|
tiflags &= ~TH_URG; /* XXX */
|
|
goto dodata; /* XXX */
|
|
}
|
|
/*
|
|
* If this segment advances the known urgent pointer,
|
|
* then mark the data stream. This should not happen
|
|
* in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
|
|
* a FIN has been received from the remote side.
|
|
* In these states we ignore the URG.
|
|
*
|
|
* According to RFC961 (Assigned Protocols),
|
|
* the urgent pointer points to the last octet
|
|
* of urgent data. We continue, however,
|
|
* to consider it to indicate the first octet
|
|
* of data past the urgent section as the original
|
|
* spec states (in one of two places).
|
|
*/
|
|
if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) {
|
|
tp->rcv_up = th->th_seq + th->th_urp;
|
|
so->so_oobmark = so->so_rcv.sb_cc +
|
|
(tp->rcv_up - tp->rcv_nxt) - 1;
|
|
if (so->so_oobmark == 0)
|
|
so->so_state |= SS_RCVATMARK;
|
|
sohasoutofband(so);
|
|
tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
|
|
}
|
|
/*
|
|
* Remove out of band data so doesn't get presented to user.
|
|
* This can happen independent of advancing the URG pointer,
|
|
* but if two URG's are pending at once, some out-of-band
|
|
* data may creep in... ick.
|
|
*/
|
|
if (th->th_urp <= (u_int16_t) tlen
|
|
#ifdef SO_OOBINLINE
|
|
&& (so->so_options & SO_OOBINLINE) == 0
|
|
#endif
|
|
)
|
|
tcp_pulloutofband(so, th, m);
|
|
} else
|
|
/*
|
|
* If no out of band data is expected,
|
|
* pull receive urgent pointer along
|
|
* with the receive window.
|
|
*/
|
|
if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
|
|
tp->rcv_up = tp->rcv_nxt;
|
|
dodata: /* XXX */
|
|
|
|
/*
|
|
* Process the segment text, merging it into the TCP sequencing queue,
|
|
* and arranging for acknowledgment of receipt if necessary.
|
|
* This process logically involves adjusting tp->rcv_wnd as data
|
|
* is presented to the user (this happens in tcp_usrreq.c,
|
|
* case PRU_RCVD). If a FIN has already been received on this
|
|
* connection then we just ignore the text.
|
|
*/
|
|
if ((tlen || (tiflags & TH_FIN)) &&
|
|
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
|
/*
|
|
* Insert segment ti into reassembly queue of tcp with
|
|
* control block tp. Return TH_FIN if reassembly now includes
|
|
* a segment with FIN. The macro form does the common case
|
|
* inline (segment is the next to be received on an
|
|
* established connection, and the queue is empty),
|
|
* avoiding linkage into and removal from the queue and
|
|
* repetition of various conversions.
|
|
* Set DELACK for segments received in order, but ack
|
|
* immediately when segments are out of order
|
|
* (so fast retransmit can work).
|
|
*/
|
|
/* NOTE: this was TCP_REASS() macro, but used only once */
|
|
TCP_REASS_LOCK(tp);
|
|
if (th->th_seq == tp->rcv_nxt &&
|
|
tp->segq.lh_first == NULL &&
|
|
tp->t_state == TCPS_ESTABLISHED) {
|
|
TCP_SETUP_ACK(tp, th);
|
|
tp->rcv_nxt += tlen;
|
|
tiflags = th->th_flags & TH_FIN;
|
|
tcpstat.tcps_rcvpack++;\
|
|
tcpstat.tcps_rcvbyte += tlen;\
|
|
sbappend(&(so)->so_rcv, m);
|
|
sorwakeup(so);
|
|
} else {
|
|
tiflags = tcp_reass(tp, th, m, &tlen);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
}
|
|
TCP_REASS_UNLOCK(tp);
|
|
|
|
/*
|
|
* Note the amount of data that peer has sent into
|
|
* our window, in order to estimate the sender's
|
|
* buffer size.
|
|
*/
|
|
len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
|
|
} else {
|
|
m_freem(m);
|
|
m = NULL;
|
|
tiflags &= ~TH_FIN;
|
|
}
|
|
|
|
/*
|
|
* If FIN is received ACK the FIN and let the user know
|
|
* that the connection is closing. Ignore a FIN received before
|
|
* the connection is fully established.
|
|
*/
|
|
if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) {
|
|
if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
|
socantrcvmore(so);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tp->rcv_nxt++;
|
|
}
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* In ESTABLISHED STATE enter the CLOSE_WAIT state.
|
|
*/
|
|
case TCPS_ESTABLISHED:
|
|
tp->t_state = TCPS_CLOSE_WAIT;
|
|
break;
|
|
|
|
/*
|
|
* If still in FIN_WAIT_1 STATE FIN has not been acked so
|
|
* enter the CLOSING state.
|
|
*/
|
|
case TCPS_FIN_WAIT_1:
|
|
tp->t_state = TCPS_CLOSING;
|
|
break;
|
|
|
|
/*
|
|
* In FIN_WAIT_2 state enter the TIME_WAIT state,
|
|
* starting the time-wait timer, turning off the other
|
|
* standard timers.
|
|
*/
|
|
case TCPS_FIN_WAIT_2:
|
|
tp->t_state = TCPS_TIME_WAIT;
|
|
tcp_canceltimers(tp);
|
|
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
|
|
soisdisconnected(so);
|
|
break;
|
|
|
|
/*
|
|
* In TIME_WAIT state restart the 2 MSL time_wait timer.
|
|
*/
|
|
case TCPS_TIME_WAIT:
|
|
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
|
|
break;
|
|
}
|
|
}
|
|
if (so->so_options & SO_DEBUG) {
|
|
tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0);
|
|
}
|
|
|
|
/*
|
|
* Return any desired output.
|
|
*/
|
|
if (needoutput || (tp->t_flags & TF_ACKNOW))
|
|
(void) tcp_output(tp);
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
|
|
badsyn:
|
|
/*
|
|
* Received a bad SYN. Increment counters and dropwithreset.
|
|
*/
|
|
tcpstat.tcps_badsyn++;
|
|
tp = NULL;
|
|
goto dropwithreset;
|
|
|
|
dropafterack:
|
|
/*
|
|
* Generate an ACK dropping incoming segment if it occupies
|
|
* sequence space, where the ACK reflects our state.
|
|
*/
|
|
if (tiflags & TH_RST)
|
|
goto drop;
|
|
m_freem(m);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
(void) tcp_output(tp);
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
|
|
dropwithreset:
|
|
/*
|
|
* Generate a RST, dropping incoming segment.
|
|
* Make ACK acceptable to originator of segment.
|
|
* Don't bother to respond if destination was broadcast/multicast.
|
|
*/
|
|
if ((tiflags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST))
|
|
goto drop;
|
|
if (ip && IN_MULTICAST(ip->ip_dst.s_addr))
|
|
goto drop;
|
|
#ifdef INET6
|
|
if (m->m_flags & M_ANYCAST6)
|
|
goto drop;
|
|
else if (ip6 && IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst))
|
|
goto drop;
|
|
#endif
|
|
/* recover the header if dropped. */
|
|
m->m_data -= hdroptlen;
|
|
m->m_len += hdroptlen;
|
|
{
|
|
/*
|
|
* need to recover version # field, which was overwritten on
|
|
* ip_cksum computation.
|
|
*/
|
|
struct ip *sip;
|
|
sip = mtod(m, struct ip *);
|
|
switch (af) {
|
|
case AF_INET:
|
|
sip->ip_v = 4;
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
sip->ip_v = 6;
|
|
break;
|
|
#endif
|
|
}
|
|
}
|
|
if (tiflags & TH_ACK)
|
|
(void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST);
|
|
else {
|
|
if (tiflags & TH_SYN)
|
|
tlen++;
|
|
(void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0,
|
|
TH_RST|TH_ACK);
|
|
}
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
|
|
drop:
|
|
/*
|
|
* Drop space held by incoming segment and return.
|
|
*/
|
|
if (tp) {
|
|
if (tp->t_inpcb)
|
|
so = tp->t_inpcb->inp_socket;
|
|
#ifdef INET6
|
|
else if (tp->t_in6pcb)
|
|
so = tp->t_in6pcb->in6p_socket;
|
|
#endif
|
|
else
|
|
so = NULL;
|
|
if (so && (so->so_options & SO_DEBUG) != 0)
|
|
tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0);
|
|
}
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
|
|
void
|
|
tcp_dooptions(tp, cp, cnt, th, oi)
|
|
struct tcpcb *tp;
|
|
u_char *cp;
|
|
int cnt;
|
|
struct tcphdr *th;
|
|
struct tcp_opt_info *oi;
|
|
{
|
|
u_int16_t mss;
|
|
int opt, optlen;
|
|
|
|
for (; cnt > 0; cnt -= optlen, cp += optlen) {
|
|
opt = cp[0];
|
|
if (opt == TCPOPT_EOL)
|
|
break;
|
|
if (opt == TCPOPT_NOP)
|
|
optlen = 1;
|
|
else {
|
|
optlen = cp[1];
|
|
if (optlen <= 0)
|
|
break;
|
|
}
|
|
switch (opt) {
|
|
|
|
default:
|
|
continue;
|
|
|
|
case TCPOPT_MAXSEG:
|
|
if (optlen != TCPOLEN_MAXSEG)
|
|
continue;
|
|
if (!(th->th_flags & TH_SYN))
|
|
continue;
|
|
bcopy(cp + 2, &mss, sizeof(mss));
|
|
oi->maxseg = ntohs(mss);
|
|
break;
|
|
|
|
case TCPOPT_WINDOW:
|
|
if (optlen != TCPOLEN_WINDOW)
|
|
continue;
|
|
if (!(th->th_flags & TH_SYN))
|
|
continue;
|
|
tp->t_flags |= TF_RCVD_SCALE;
|
|
tp->requested_s_scale = cp[2];
|
|
if (tp->requested_s_scale > TCP_MAX_WINSHIFT) {
|
|
#if 0 /*XXX*/
|
|
char *p;
|
|
|
|
if (ip)
|
|
p = ntohl(ip->ip_src);
|
|
#ifdef INET6
|
|
else if (ip6)
|
|
p = ip6_sprintf(&ip6->ip6_src);
|
|
#endif
|
|
else
|
|
p = "(unknown)";
|
|
log(LOG_ERR, "TCP: invalid wscale %d from %s, "
|
|
"assuming %d\n",
|
|
tp->requested_s_scale, p,
|
|
TCP_MAX_WINSHIFT);
|
|
#else
|
|
log(LOG_ERR, "TCP: invalid wscale %d, "
|
|
"assuming %d\n",
|
|
tp->requested_s_scale,
|
|
TCP_MAX_WINSHIFT);
|
|
#endif
|
|
tp->requested_s_scale = TCP_MAX_WINSHIFT;
|
|
}
|
|
break;
|
|
|
|
case TCPOPT_TIMESTAMP:
|
|
if (optlen != TCPOLEN_TIMESTAMP)
|
|
continue;
|
|
oi->ts_present = 1;
|
|
bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val));
|
|
NTOHL(oi->ts_val);
|
|
bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr));
|
|
NTOHL(oi->ts_ecr);
|
|
|
|
/*
|
|
* A timestamp received in a SYN makes
|
|
* it ok to send timestamp requests and replies.
|
|
*/
|
|
if (th->th_flags & TH_SYN) {
|
|
tp->t_flags |= TF_RCVD_TSTMP;
|
|
tp->ts_recent = oi->ts_val;
|
|
tp->ts_recent_age = tcp_now;
|
|
}
|
|
break;
|
|
case TCPOPT_SACK_PERMITTED:
|
|
if (optlen != TCPOLEN_SACK_PERMITTED)
|
|
continue;
|
|
if (!(th->th_flags & TH_SYN))
|
|
continue;
|
|
tp->t_flags &= ~TF_CANT_TXSACK;
|
|
break;
|
|
|
|
case TCPOPT_SACK:
|
|
if (tp->t_flags & TF_IGNR_RXSACK)
|
|
continue;
|
|
if (optlen % 8 != 2 || optlen < 10)
|
|
continue;
|
|
cp += 2;
|
|
optlen -= 2;
|
|
for (; optlen > 0; cp -= 8, optlen -= 8) {
|
|
tcp_seq lwe, rwe;
|
|
bcopy((char *)cp, (char *) &lwe, sizeof(lwe));
|
|
NTOHL(lwe);
|
|
bcopy((char *)cp, (char *) &rwe, sizeof(rwe));
|
|
NTOHL(rwe);
|
|
/* tcp_mark_sacked(tp, lwe, rwe); */
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Pull out of band byte out of a segment so
|
|
* it doesn't appear in the user's data queue.
|
|
* It is still reflected in the segment length for
|
|
* sequencing purposes.
|
|
*/
|
|
void
|
|
tcp_pulloutofband(so, th, m)
|
|
struct socket *so;
|
|
struct tcphdr *th;
|
|
register struct mbuf *m;
|
|
{
|
|
int cnt = th->th_urp - 1;
|
|
|
|
while (cnt >= 0) {
|
|
if (m->m_len > cnt) {
|
|
char *cp = mtod(m, caddr_t) + cnt;
|
|
struct tcpcb *tp = sototcpcb(so);
|
|
|
|
tp->t_iobc = *cp;
|
|
tp->t_oobflags |= TCPOOB_HAVEDATA;
|
|
bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1));
|
|
m->m_len--;
|
|
return;
|
|
}
|
|
cnt -= m->m_len;
|
|
m = m->m_next;
|
|
if (m == 0)
|
|
break;
|
|
}
|
|
panic("tcp_pulloutofband");
|
|
}
|
|
|
|
/*
|
|
* Collect new round-trip time estimate
|
|
* and update averages and current timeout.
|
|
*/
|
|
void
|
|
tcp_xmit_timer(tp, rtt)
|
|
register struct tcpcb *tp;
|
|
short rtt;
|
|
{
|
|
register short delta;
|
|
short rttmin;
|
|
|
|
tcpstat.tcps_rttupdated++;
|
|
--rtt;
|
|
if (tp->t_srtt != 0) {
|
|
/*
|
|
* srtt is stored as fixed point with 3 bits after the
|
|
* binary point (i.e., scaled by 8). The following magic
|
|
* is equivalent to the smoothing algorithm in rfc793 with
|
|
* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
|
|
* point). Adjust rtt to origin 0.
|
|
*/
|
|
delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT);
|
|
if ((tp->t_srtt += delta) <= 0)
|
|
tp->t_srtt = 1 << 2;
|
|
/*
|
|
* We accumulate a smoothed rtt variance (actually, a
|
|
* smoothed mean difference), then set the retransmit
|
|
* timer to smoothed rtt + 4 times the smoothed variance.
|
|
* rttvar is stored as fixed point with 2 bits after the
|
|
* binary point (scaled by 4). The following is
|
|
* equivalent to rfc793 smoothing with an alpha of .75
|
|
* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
|
|
* rfc793's wired-in beta.
|
|
*/
|
|
if (delta < 0)
|
|
delta = -delta;
|
|
delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
|
|
if ((tp->t_rttvar += delta) <= 0)
|
|
tp->t_rttvar = 1 << 2;
|
|
} else {
|
|
/*
|
|
* No rtt measurement yet - use the unsmoothed rtt.
|
|
* Set the variance to half the rtt (so our first
|
|
* retransmit happens at 3*rtt).
|
|
*/
|
|
tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2);
|
|
tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1);
|
|
}
|
|
tp->t_rtt = 0;
|
|
tp->t_rxtshift = 0;
|
|
|
|
/*
|
|
* the retransmit should happen at rtt + 4 * rttvar.
|
|
* Because of the way we do the smoothing, srtt and rttvar
|
|
* will each average +1/2 tick of bias. When we compute
|
|
* the retransmit timer, we want 1/2 tick of rounding and
|
|
* 1 extra tick because of +-1/2 tick uncertainty in the
|
|
* firing of the timer. The bias will give us exactly the
|
|
* 1.5 tick we need. But, because the bias is
|
|
* statistical, we have to test that we don't drop below
|
|
* the minimum feasible timer (which is 2 ticks).
|
|
*/
|
|
if (tp->t_rttmin > rtt + 2)
|
|
rttmin = tp->t_rttmin;
|
|
else
|
|
rttmin = rtt + 2;
|
|
TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), rttmin, TCPTV_REXMTMAX);
|
|
|
|
/*
|
|
* We received an ack for a packet that wasn't retransmitted;
|
|
* it is probably safe to discard any error indications we've
|
|
* received recently. This isn't quite right, but close enough
|
|
* for now (a route might have failed after we sent a segment,
|
|
* and the return path might not be symmetrical).
|
|
*/
|
|
tp->t_softerror = 0;
|
|
}
|
|
|
|
/*
|
|
* Checks for partial ack. If partial ack arrives, force the retransmission
|
|
* of the next unacknowledged segment, do not clear tp->t_dupacks, and return
|
|
* 1. By setting snd_nxt to ti_ack, this forces retransmission timer to
|
|
* be started again. If the ack advances at least to tp->snd_recover, return 0.
|
|
*/
|
|
int
|
|
tcp_newreno(tp, th)
|
|
struct tcpcb *tp;
|
|
struct tcphdr *th;
|
|
{
|
|
if (SEQ_LT(th->th_ack, tp->snd_recover)) {
|
|
tcp_seq onxt = tp->snd_nxt;
|
|
tcp_seq ouna = tp->snd_una; /* Haven't updated snd_una yet*/
|
|
u_long ocwnd = tp->snd_cwnd;
|
|
TCP_TIMER_DISARM(tp, TCPT_REXMT);
|
|
tp->t_rtt = 0;
|
|
tp->snd_nxt = th->th_ack;
|
|
tp->snd_cwnd = tp->t_segsz;
|
|
tp->snd_una = th->th_ack;
|
|
(void) tcp_output(tp);
|
|
tp->snd_cwnd = ocwnd;
|
|
tp->snd_una = ouna;
|
|
if (SEQ_GT(onxt, tp->snd_nxt))
|
|
tp->snd_nxt = onxt;
|
|
/*
|
|
* Partial window deflation. Relies on fact that tp->snd_una
|
|
* not updated yet.
|
|
*/
|
|
tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* TCP compressed state engine. Currently used to hold compressed
|
|
* state for SYN_RECEIVED.
|
|
*/
|
|
|
|
u_long syn_cache_count;
|
|
u_int32_t syn_hash1, syn_hash2;
|
|
|
|
#define SYN_HASH(sa, sp, dp) \
|
|
((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \
|
|
((u_int32_t)(sp)))^syn_hash2)))
|
|
#ifndef INET6
|
|
#define SYN_HASHALL(hash, src, dst) \
|
|
do { \
|
|
hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \
|
|
((struct sockaddr_in *)(src))->sin_port, \
|
|
((struct sockaddr_in *)(dst))->sin_port); \
|
|
} while (0)
|
|
#else
|
|
#define SYN_HASH6(sa, sp, dp) \
|
|
((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \
|
|
(((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \
|
|
& 0x7fffffff)
|
|
|
|
#define SYN_HASHALL(hash, src, dst) \
|
|
do { \
|
|
switch ((src)->sa_family) { \
|
|
case AF_INET: \
|
|
hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \
|
|
((struct sockaddr_in *)(src))->sin_port, \
|
|
((struct sockaddr_in *)(dst))->sin_port); \
|
|
break; \
|
|
case AF_INET6: \
|
|
hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \
|
|
((struct sockaddr_in6 *)(src))->sin6_port, \
|
|
((struct sockaddr_in6 *)(dst))->sin6_port); \
|
|
break; \
|
|
default: \
|
|
hash = 0; \
|
|
} \
|
|
} while (0)
|
|
#endif /* INET6 */
|
|
|
|
#define SYN_CACHE_RM(sc) \
|
|
do { \
|
|
LIST_REMOVE((sc), sc_bucketq); \
|
|
tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \
|
|
TAILQ_REMOVE(&tcp_syn_cache_timeq[(sc)->sc_rxtshift], (sc), sc_timeq); \
|
|
syn_cache_count--; \
|
|
} while (0)
|
|
|
|
#define SYN_CACHE_PUT(sc) \
|
|
do { \
|
|
if ((sc)->sc_ipopts) \
|
|
(void) m_free((sc)->sc_ipopts); \
|
|
if ((sc)->sc_route4.ro_rt != NULL) \
|
|
RTFREE((sc)->sc_route4.ro_rt); \
|
|
pool_put(&syn_cache_pool, (sc)); \
|
|
} while (0)
|
|
|
|
struct pool syn_cache_pool;
|
|
|
|
/*
|
|
* We don't estimate RTT with SYNs, so each packet starts with the default
|
|
* RTT and each timer queue has a fixed timeout value. This allows us to
|
|
* optimize the timer queues somewhat.
|
|
*/
|
|
#define SYN_CACHE_TIMER_ARM(sc) \
|
|
do { \
|
|
TCPT_RANGESET((sc)->sc_rxtcur, \
|
|
TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \
|
|
TCPTV_REXMTMAX); \
|
|
PRT_SLOW_ARM((sc)->sc_rexmt, (sc)->sc_rxtcur); \
|
|
} while (0)
|
|
|
|
TAILQ_HEAD(, syn_cache) tcp_syn_cache_timeq[TCP_MAXRXTSHIFT + 1];
|
|
|
|
void
|
|
syn_cache_init()
|
|
{
|
|
int i;
|
|
|
|
/* Initialize the hash buckets. */
|
|
for (i = 0; i < tcp_syn_cache_size; i++)
|
|
LIST_INIT(&tcp_syn_cache[i].sch_bucket);
|
|
|
|
/* Initialize the timer queues. */
|
|
for (i = 0; i <= TCP_MAXRXTSHIFT; i++)
|
|
TAILQ_INIT(&tcp_syn_cache_timeq[i]);
|
|
|
|
/* Initialize the syn cache pool. */
|
|
pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0,
|
|
"synpl", 0, NULL, NULL, M_PCB);
|
|
}
|
|
|
|
void
|
|
syn_cache_insert(sc)
|
|
struct syn_cache *sc;
|
|
{
|
|
struct syn_cache_head *scp;
|
|
struct syn_cache *sc2;
|
|
int s, i;
|
|
|
|
/*
|
|
* If there are no entries in the hash table, reinitialize
|
|
* the hash secrets.
|
|
*/
|
|
if (syn_cache_count == 0) {
|
|
struct timeval tv;
|
|
microtime(&tv);
|
|
syn_hash1 = random() ^ (u_long)≻
|
|
syn_hash2 = random() ^ tv.tv_usec;
|
|
}
|
|
|
|
SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa);
|
|
sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size;
|
|
scp = &tcp_syn_cache[sc->sc_bucketidx];
|
|
|
|
/*
|
|
* Make sure that we don't overflow the per-bucket
|
|
* limit or the total cache size limit.
|
|
*/
|
|
s = splsoftnet();
|
|
if (scp->sch_length >= tcp_syn_bucket_limit) {
|
|
tcpstat.tcps_sc_bucketoverflow++;
|
|
/*
|
|
* The bucket is full. Toss the oldest element in the
|
|
* bucket. This will be the entry with our bucket
|
|
* index closest to the front of the timer queue with
|
|
* the largest timeout value.
|
|
*
|
|
* Note: This timer queue traversal may be expensive, so
|
|
* we hope that this doesn't happen very often. It is
|
|
* much more likely that we'll overflow the entire
|
|
* cache, which is much easier to handle; see below.
|
|
*/
|
|
for (i = TCP_MAXRXTSHIFT; i >= 0; i--) {
|
|
for (sc2 = TAILQ_FIRST(&tcp_syn_cache_timeq[i]);
|
|
sc2 != NULL;
|
|
sc2 = TAILQ_NEXT(sc2, sc_timeq)) {
|
|
if (sc2->sc_bucketidx == sc->sc_bucketidx) {
|
|
SYN_CACHE_RM(sc2);
|
|
SYN_CACHE_PUT(sc2);
|
|
goto insert; /* 2 level break */
|
|
}
|
|
}
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
/*
|
|
* This should never happen; we should always find an
|
|
* entry in our bucket.
|
|
*/
|
|
panic("syn_cache_insert: bucketoverflow: impossible");
|
|
#endif
|
|
} else if (syn_cache_count >= tcp_syn_cache_limit) {
|
|
tcpstat.tcps_sc_overflowed++;
|
|
/*
|
|
* The cache is full. Toss the oldest entry in the
|
|
* entire cache. This is the front entry in the
|
|
* first non-empty timer queue with the largest
|
|
* timeout value.
|
|
*/
|
|
for (i = TCP_MAXRXTSHIFT; i >= 0; i--) {
|
|
sc2 = TAILQ_FIRST(&tcp_syn_cache_timeq[i]);
|
|
if (sc2 == NULL)
|
|
continue;
|
|
SYN_CACHE_RM(sc2);
|
|
SYN_CACHE_PUT(sc2);
|
|
goto insert; /* symmetry with above */
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
/*
|
|
* This should never happen; we should always find an
|
|
* entry in the cache.
|
|
*/
|
|
panic("syn_cache_insert: cache overflow: impossible");
|
|
#endif
|
|
}
|
|
|
|
insert:
|
|
/*
|
|
* Initialize the entry's timer.
|
|
*/
|
|
sc->sc_rxttot = 0;
|
|
sc->sc_rxtshift = 0;
|
|
SYN_CACHE_TIMER_ARM(sc);
|
|
TAILQ_INSERT_TAIL(&tcp_syn_cache_timeq[sc->sc_rxtshift], sc, sc_timeq);
|
|
|
|
/* Put it into the bucket. */
|
|
LIST_INSERT_HEAD(&scp->sch_bucket, sc, sc_bucketq);
|
|
scp->sch_length++;
|
|
syn_cache_count++;
|
|
|
|
tcpstat.tcps_sc_added++;
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
|
|
* If we have retransmitted an entry the maximum number of times, expire
|
|
* that entry.
|
|
*/
|
|
void
|
|
syn_cache_timer()
|
|
{
|
|
struct syn_cache *sc, *nsc;
|
|
int i, s;
|
|
|
|
s = splsoftnet();
|
|
|
|
/*
|
|
* First, get all the entries that need to be retransmitted, or
|
|
* must be expired due to exceeding the initial keepalive time.
|
|
*/
|
|
for (i = 0; i < TCP_MAXRXTSHIFT; i++) {
|
|
for (sc = TAILQ_FIRST(&tcp_syn_cache_timeq[i]);
|
|
sc != NULL && PRT_SLOW_ISEXPIRED(sc->sc_rexmt);
|
|
sc = nsc) {
|
|
nsc = TAILQ_NEXT(sc, sc_timeq);
|
|
|
|
/*
|
|
* Compute the total amount of time this entry has
|
|
* been on a queue. If this entry has been on longer
|
|
* than the keep alive timer would allow, expire it.
|
|
*/
|
|
sc->sc_rxttot += sc->sc_rxtcur;
|
|
if (sc->sc_rxttot >= TCPTV_KEEP_INIT) {
|
|
tcpstat.tcps_sc_timed_out++;
|
|
SYN_CACHE_RM(sc);
|
|
SYN_CACHE_PUT(sc);
|
|
continue;
|
|
}
|
|
|
|
tcpstat.tcps_sc_retransmitted++;
|
|
(void) syn_cache_respond(sc, NULL);
|
|
|
|
/* Advance this entry onto the next timer queue. */
|
|
TAILQ_REMOVE(&tcp_syn_cache_timeq[i], sc, sc_timeq);
|
|
sc->sc_rxtshift = i + 1;
|
|
SYN_CACHE_TIMER_ARM(sc);
|
|
TAILQ_INSERT_TAIL(&tcp_syn_cache_timeq[sc->sc_rxtshift],
|
|
sc, sc_timeq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now get all the entries that are expired due to too many
|
|
* retransmissions.
|
|
*/
|
|
for (sc = TAILQ_FIRST(&tcp_syn_cache_timeq[TCP_MAXRXTSHIFT]);
|
|
sc != NULL && PRT_SLOW_ISEXPIRED(sc->sc_rexmt);
|
|
sc = nsc) {
|
|
nsc = TAILQ_NEXT(sc, sc_timeq);
|
|
tcpstat.tcps_sc_timed_out++;
|
|
SYN_CACHE_RM(sc);
|
|
SYN_CACHE_PUT(sc);
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Find an entry in the syn cache.
|
|
*/
|
|
struct syn_cache *
|
|
syn_cache_lookup(src, dst, headp)
|
|
struct sockaddr *src;
|
|
struct sockaddr *dst;
|
|
struct syn_cache_head **headp;
|
|
{
|
|
struct syn_cache *sc;
|
|
struct syn_cache_head *scp;
|
|
u_int32_t hash;
|
|
int s;
|
|
|
|
SYN_HASHALL(hash, src, dst);
|
|
|
|
scp = &tcp_syn_cache[hash % tcp_syn_cache_size];
|
|
*headp = scp;
|
|
s = splsoftnet();
|
|
for (sc = LIST_FIRST(&scp->sch_bucket); sc != NULL;
|
|
sc = LIST_NEXT(sc, sc_bucketq)) {
|
|
if (sc->sc_hash != hash)
|
|
continue;
|
|
if (!bcmp(&sc->sc_src, src, src->sa_len) &&
|
|
!bcmp(&sc->sc_dst, dst, dst->sa_len)) {
|
|
splx(s);
|
|
return (sc);
|
|
}
|
|
}
|
|
splx(s);
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* This function gets called when we receive an ACK for a
|
|
* socket in the LISTEN state. We look up the connection
|
|
* in the syn cache, and if its there, we pull it out of
|
|
* the cache and turn it into a full-blown connection in
|
|
* the SYN-RECEIVED state.
|
|
*
|
|
* The return values may not be immediately obvious, and their effects
|
|
* can be subtle, so here they are:
|
|
*
|
|
* NULL SYN was not found in cache; caller should drop the
|
|
* packet and send an RST.
|
|
*
|
|
* -1 We were unable to create the new connection, and are
|
|
* aborting it. An ACK,RST is being sent to the peer
|
|
* (unless we got screwey sequence numbners; see below),
|
|
* because the 3-way handshake has been completed. Caller
|
|
* should not free the mbuf, since we may be using it. If
|
|
* we are not, we will free it.
|
|
*
|
|
* Otherwise, the return value is a pointer to the new socket
|
|
* associated with the connection.
|
|
*/
|
|
struct socket *
|
|
syn_cache_get(src, dst, th, hlen, tlen, so, m)
|
|
struct sockaddr *src;
|
|
struct sockaddr *dst;
|
|
struct tcphdr *th;
|
|
unsigned int hlen, tlen;
|
|
struct socket *so;
|
|
struct mbuf *m;
|
|
{
|
|
struct syn_cache *sc;
|
|
struct syn_cache_head *scp;
|
|
register struct inpcb *inp = NULL;
|
|
#ifdef INET6
|
|
register struct in6pcb *in6p = NULL;
|
|
#endif
|
|
register struct tcpcb *tp = 0;
|
|
struct mbuf *am;
|
|
int s;
|
|
struct socket *oso;
|
|
|
|
s = splsoftnet();
|
|
if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) {
|
|
splx(s);
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* Verify the sequence and ack numbers. Try getting the correct
|
|
* response again.
|
|
*/
|
|
if ((th->th_ack != sc->sc_iss + 1) ||
|
|
SEQ_LEQ(th->th_seq, sc->sc_irs) ||
|
|
SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) {
|
|
(void) syn_cache_respond(sc, m);
|
|
splx(s);
|
|
return ((struct socket *)(-1));
|
|
}
|
|
|
|
/* Remove this cache entry */
|
|
SYN_CACHE_RM(sc);
|
|
splx(s);
|
|
|
|
/*
|
|
* Ok, create the full blown connection, and set things up
|
|
* as they would have been set up if we had created the
|
|
* connection when the SYN arrived. If we can't create
|
|
* the connection, abort it.
|
|
*/
|
|
/*
|
|
* inp still has the OLD in_pcb stuff, set the
|
|
* v6-related flags on the new guy, too. This is
|
|
* done particularly for the case where an AF_INET6
|
|
* socket is bound only to a port, and a v4 connection
|
|
* comes in on that port.
|
|
* we also copy the flowinfo from the original pcb
|
|
* to the new one.
|
|
*/
|
|
{
|
|
struct inpcb *parentinpcb;
|
|
|
|
parentinpcb = (struct inpcb *)so->so_pcb;
|
|
|
|
oso = so;
|
|
so = sonewconn(so, SS_ISCONNECTED);
|
|
if (so == NULL)
|
|
goto resetandabort;
|
|
|
|
switch (so->so_proto->pr_domain->dom_family) {
|
|
case AF_INET:
|
|
inp = sotoinpcb(so);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
in6p = sotoin6pcb(so);
|
|
#if 0 /*def INET6*/
|
|
inp->inp_flags |= (parentinpcb->inp_flags &
|
|
(INP_IPV6 | INP_IPV6_UNDEC | INP_IPV6_MAPPED));
|
|
if ((inp->inp_flags & INP_IPV6) &&
|
|
!(inp->inp_flags & INP_IPV6_MAPPED)) {
|
|
inp->inp_ipv6.ip6_hlim = parentinpcb->inp_ipv6.ip6_hlim;
|
|
inp->inp_ipv6.ip6_vfc = parentinpcb->inp_ipv6.ip6_vfc;
|
|
}
|
|
#endif
|
|
break;
|
|
#endif
|
|
}
|
|
}
|
|
switch (src->sa_family) {
|
|
case AF_INET:
|
|
if (inp) {
|
|
inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr;
|
|
inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port;
|
|
inp->inp_options = ip_srcroute();
|
|
in_pcbstate(inp, INP_BOUND);
|
|
if (inp->inp_options == NULL) {
|
|
inp->inp_options = sc->sc_ipopts;
|
|
sc->sc_ipopts = NULL;
|
|
}
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p) {
|
|
/* IPv4 packet to AF_INET6 socket */
|
|
bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr));
|
|
in6p->in6p_laddr.s6_addr16[5] = htons(0xffff);
|
|
bcopy(&((struct sockaddr_in *)dst)->sin_addr,
|
|
&in6p->in6p_laddr.s6_addr32[3],
|
|
sizeof(((struct sockaddr_in *)dst)->sin_addr));
|
|
in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port;
|
|
in6totcpcb(in6p)->t_family = AF_INET;
|
|
}
|
|
#endif
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
if (in6p) {
|
|
in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr;
|
|
in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port;
|
|
#if 0
|
|
in6p->in6p_flowinfo = ip6->ip6_flow & IPV6_FLOWINFO_MASK;
|
|
/*inp->inp_options = ip6_srcroute();*/ /* soon. */
|
|
#endif
|
|
}
|
|
break;
|
|
#endif
|
|
}
|
|
#ifdef INET6
|
|
if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) {
|
|
struct in6pcb *oin6p = sotoin6pcb(oso);
|
|
/* inherit socket options from the listening socket */
|
|
in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS);
|
|
if (in6p->in6p_flags & IN6P_CONTROLOPTS) {
|
|
m_freem(in6p->in6p_options);
|
|
in6p->in6p_options = 0;
|
|
}
|
|
ip6_savecontrol(in6p, &in6p->in6p_options,
|
|
mtod(m, struct ip6_hdr *), m);
|
|
}
|
|
#endif
|
|
|
|
#ifdef IPSEC
|
|
{
|
|
struct secpolicy *sp;
|
|
if (inp) {
|
|
sp = ipsec_copy_policy(sotoinpcb(oso)->inp_sp);
|
|
if (sp) {
|
|
key_freesp(inp->inp_sp);
|
|
inp->inp_sp = sp;
|
|
} else
|
|
printf("tcp_input: could not copy policy\n");
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p) {
|
|
sp = ipsec_copy_policy(sotoin6pcb(oso)->in6p_sp);
|
|
if (sp) {
|
|
key_freesp(in6p->in6p_sp);
|
|
in6p->in6p_sp = sp;
|
|
} else
|
|
printf("tcp_input: could not copy policy\n");
|
|
}
|
|
#endif
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Give the new socket our cached route reference.
|
|
*/
|
|
if (inp)
|
|
inp->inp_route = sc->sc_route4; /* struct assignment */
|
|
#ifdef INET6
|
|
else
|
|
in6p->in6p_route = sc->sc_route6;
|
|
#endif
|
|
sc->sc_route4.ro_rt = NULL;
|
|
|
|
am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */
|
|
if (am == NULL)
|
|
goto resetandabort;
|
|
am->m_len = src->sa_len;
|
|
bcopy(src, mtod(am, caddr_t), src->sa_len);
|
|
if (inp) {
|
|
if (in_pcbconnect(inp, am)) {
|
|
(void) m_free(am);
|
|
goto resetandabort;
|
|
}
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p) {
|
|
if (src->sa_family == AF_INET) {
|
|
/* IPv4 packet to AF_INET6 socket */
|
|
struct sockaddr_in6 *sin6;
|
|
sin6 = mtod(am, struct sockaddr_in6 *);
|
|
am->m_len = sizeof(*sin6);
|
|
bzero(sin6, sizeof(*sin6));
|
|
sin6->sin6_family = AF_INET6;
|
|
sin6->sin6_len = sizeof(*sin6);
|
|
sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port;
|
|
sin6->sin6_addr.s6_addr16[5] = htons(0xffff);
|
|
bcopy(&((struct sockaddr_in *)src)->sin_addr,
|
|
&sin6->sin6_addr.s6_addr32[3],
|
|
sizeof(sin6->sin6_addr.s6_addr32[3]));
|
|
}
|
|
if (in6_pcbconnect(in6p, am)) {
|
|
(void) m_free(am);
|
|
goto resetandabort;
|
|
}
|
|
}
|
|
#endif
|
|
else {
|
|
(void) m_free(am);
|
|
goto resetandabort;
|
|
}
|
|
(void) m_free(am);
|
|
|
|
if (inp)
|
|
tp = intotcpcb(inp);
|
|
#ifdef INET6
|
|
else if (in6p)
|
|
tp = in6totcpcb(in6p);
|
|
#endif
|
|
else
|
|
tp = NULL;
|
|
if (sc->sc_request_r_scale != 15) {
|
|
tp->requested_s_scale = sc->sc_requested_s_scale;
|
|
tp->request_r_scale = sc->sc_request_r_scale;
|
|
tp->snd_scale = sc->sc_requested_s_scale;
|
|
tp->rcv_scale = sc->sc_request_r_scale;
|
|
tp->t_flags |= TF_RCVD_SCALE;
|
|
}
|
|
if (sc->sc_flags & SCF_TIMESTAMP)
|
|
tp->t_flags |= TF_RCVD_TSTMP;
|
|
|
|
tp->t_template = tcp_template(tp);
|
|
if (tp->t_template == 0) {
|
|
tp = tcp_drop(tp, ENOBUFS); /* destroys socket */
|
|
so = NULL;
|
|
m_freem(m);
|
|
goto abort;
|
|
}
|
|
|
|
tp->iss = sc->sc_iss;
|
|
tp->irs = sc->sc_irs;
|
|
tcp_sendseqinit(tp);
|
|
tcp_rcvseqinit(tp);
|
|
tp->t_state = TCPS_SYN_RECEIVED;
|
|
TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT);
|
|
tcpstat.tcps_accepts++;
|
|
|
|
/* Initialize tp->t_ourmss before we deal with the peer's! */
|
|
tp->t_ourmss = sc->sc_ourmaxseg;
|
|
tcp_mss_from_peer(tp, sc->sc_peermaxseg);
|
|
|
|
/*
|
|
* Initialize the initial congestion window. If we
|
|
* had to retransmit the SYN,ACK, we must initialize cwnd
|
|
* to 1 segment (i.e. the Loss Window).
|
|
*/
|
|
if (sc->sc_rxtshift)
|
|
tp->snd_cwnd = tp->t_peermss;
|
|
else
|
|
tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, tp->t_peermss);
|
|
|
|
tcp_rmx_rtt(tp);
|
|
tp->snd_wl1 = sc->sc_irs;
|
|
tp->rcv_up = sc->sc_irs + 1;
|
|
|
|
/*
|
|
* This is what whould have happened in tcp_ouput() when
|
|
* the SYN,ACK was sent.
|
|
*/
|
|
tp->snd_up = tp->snd_una;
|
|
tp->snd_max = tp->snd_nxt = tp->iss+1;
|
|
TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur);
|
|
if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv))
|
|
tp->rcv_adv = tp->rcv_nxt + sc->sc_win;
|
|
tp->last_ack_sent = tp->rcv_nxt;
|
|
|
|
tcpstat.tcps_sc_completed++;
|
|
SYN_CACHE_PUT(sc);
|
|
return (so);
|
|
|
|
resetandabort:
|
|
(void) tcp_respond(NULL, m, m, th,
|
|
th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK);
|
|
abort:
|
|
if (so != NULL)
|
|
(void) soabort(so);
|
|
SYN_CACHE_PUT(sc);
|
|
tcpstat.tcps_sc_aborted++;
|
|
return ((struct socket *)(-1));
|
|
}
|
|
|
|
/*
|
|
* This function is called when we get a RST for a
|
|
* non-existant connection, so that we can see if the
|
|
* connection is in the syn cache. If it is, zap it.
|
|
*/
|
|
|
|
void
|
|
syn_cache_reset(src, dst, th)
|
|
struct sockaddr *src;
|
|
struct sockaddr *dst;
|
|
struct tcphdr *th;
|
|
{
|
|
struct syn_cache *sc;
|
|
struct syn_cache_head *scp;
|
|
int s = splsoftnet();
|
|
|
|
if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) {
|
|
splx(s);
|
|
return;
|
|
}
|
|
if (SEQ_LT(th->th_seq, sc->sc_irs) ||
|
|
SEQ_GT(th->th_seq, sc->sc_irs+1)) {
|
|
splx(s);
|
|
return;
|
|
}
|
|
SYN_CACHE_RM(sc);
|
|
splx(s);
|
|
tcpstat.tcps_sc_reset++;
|
|
SYN_CACHE_PUT(sc);
|
|
}
|
|
|
|
void
|
|
syn_cache_unreach(src, dst, th)
|
|
struct sockaddr *src;
|
|
struct sockaddr *dst;
|
|
struct tcphdr *th;
|
|
{
|
|
struct syn_cache *sc;
|
|
struct syn_cache_head *scp;
|
|
int s;
|
|
|
|
s = splsoftnet();
|
|
if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) {
|
|
splx(s);
|
|
return;
|
|
}
|
|
/* If the sequence number != sc_iss, then it's a bogus ICMP msg */
|
|
if (ntohl (th->th_seq) != sc->sc_iss) {
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If we've rertransmitted 3 times and this is our second error,
|
|
* we remove the entry. Otherwise, we allow it to continue on.
|
|
* This prevents us from incorrectly nuking an entry during a
|
|
* spurious network outage.
|
|
*
|
|
* See tcp_notify().
|
|
*/
|
|
if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) {
|
|
sc->sc_flags |= SCF_UNREACH;
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
SYN_CACHE_RM(sc);
|
|
splx(s);
|
|
tcpstat.tcps_sc_unreach++;
|
|
SYN_CACHE_PUT(sc);
|
|
}
|
|
|
|
/*
|
|
* Given a LISTEN socket and an inbound SYN request, add
|
|
* this to the syn cache, and send back a segment:
|
|
* <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
|
|
* to the source.
|
|
*
|
|
* IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
|
|
* Doing so would require that we hold onto the data and deliver it
|
|
* to the application. However, if we are the target of a SYN-flood
|
|
* DoS attack, an attacker could send data which would eventually
|
|
* consume all available buffer space if it were ACKed. By not ACKing
|
|
* the data, we avoid this DoS scenario.
|
|
*/
|
|
|
|
int
|
|
syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi)
|
|
struct sockaddr *src;
|
|
struct sockaddr *dst;
|
|
struct tcphdr *th;
|
|
unsigned int hlen;
|
|
struct socket *so;
|
|
struct mbuf *m;
|
|
u_char *optp;
|
|
int optlen;
|
|
struct tcp_opt_info *oi;
|
|
{
|
|
struct tcpcb tb, *tp;
|
|
long win;
|
|
struct syn_cache *sc;
|
|
struct syn_cache_head *scp;
|
|
struct mbuf *ipopts;
|
|
#ifdef IPSEC
|
|
size_t ipsechdrsiz;
|
|
#endif
|
|
|
|
tp = sototcpcb(so);
|
|
|
|
/*
|
|
* RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
|
|
* in_broadcast() should never return true on a received
|
|
* packet with M_BCAST not set.
|
|
*/
|
|
if (m->m_flags & (M_BCAST|M_MCAST))
|
|
return 0;
|
|
#ifdef INET6
|
|
if (m->m_flags & M_ANYCAST6)
|
|
return 0;
|
|
#endif
|
|
|
|
switch (src->sa_family) {
|
|
case AF_INET:
|
|
if (IN_MULTICAST(((struct sockaddr_in *)src)->sin_addr.s_addr)
|
|
|| IN_MULTICAST(((struct sockaddr_in *)dst)->sin_addr.s_addr))
|
|
return 0;
|
|
#ifdef IPSEC
|
|
ipsechdrsiz = ipsec4_hdrsiz_tcp(tp);
|
|
#endif
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
if (IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *)src)->sin6_addr)
|
|
|| IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *)dst)->sin6_addr))
|
|
return 0;
|
|
#if defined(IPSEC) && !defined(TCP6)
|
|
ipsechdrsiz = ipsec6_hdrsiz_tcp(tp);
|
|
#endif
|
|
break;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Initialize some local state.
|
|
*/
|
|
win = sbspace(&so->so_rcv);
|
|
if (win > TCP_MAXWIN)
|
|
win = TCP_MAXWIN;
|
|
|
|
if (src->sa_family == AF_INET) {
|
|
/*
|
|
* Remember the IP options, if any.
|
|
*/
|
|
ipopts = ip_srcroute();
|
|
} else
|
|
ipopts = NULL;
|
|
|
|
if (optp) {
|
|
tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
|
|
tcp_dooptions(&tb, optp, optlen, th, oi);
|
|
} else
|
|
tb.t_flags = 0;
|
|
|
|
/*
|
|
* See if we already have an entry for this connection.
|
|
* If we do, resend the SYN,ACK. We do not count this
|
|
* as a retransmission (XXX though maybe we should).
|
|
*/
|
|
if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) {
|
|
tcpstat.tcps_sc_dupesyn++;
|
|
if (ipopts) {
|
|
/*
|
|
* If we were remembering a previous source route,
|
|
* forget it and use the new one we've been given.
|
|
*/
|
|
if (sc->sc_ipopts)
|
|
(void) m_free(sc->sc_ipopts);
|
|
sc->sc_ipopts = ipopts;
|
|
}
|
|
sc->sc_timestamp = tb.ts_recent;
|
|
if (syn_cache_respond(sc, m) == 0) {
|
|
tcpstat.tcps_sndacks++;
|
|
tcpstat.tcps_sndtotal++;
|
|
}
|
|
return (1);
|
|
}
|
|
|
|
sc = pool_get(&syn_cache_pool, PR_NOWAIT);
|
|
if (sc == NULL) {
|
|
if (ipopts)
|
|
(void) m_free(ipopts);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Fill in the cache, and put the necessary IP and TCP
|
|
* options into the reply.
|
|
*/
|
|
bzero(sc, sizeof(struct syn_cache));
|
|
bcopy(src, &sc->sc_src, src->sa_len);
|
|
bcopy(dst, &sc->sc_dst, dst->sa_len);
|
|
sc->sc_flags = 0;
|
|
sc->sc_ipopts = ipopts;
|
|
sc->sc_irs = th->th_seq;
|
|
sc->sc_iss = tcp_new_iss(sc, sizeof(struct syn_cache), 0);
|
|
sc->sc_peermaxseg = oi->maxseg;
|
|
sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ?
|
|
m->m_pkthdr.rcvif : NULL);
|
|
#ifdef IPSEC
|
|
if (ipsechdrsiz < sc->sc_ourmaxseg)
|
|
sc->sc_ourmaxseg -= ipsechdrsiz;
|
|
#endif
|
|
sc->sc_win = win;
|
|
sc->sc_timestamp = tb.ts_recent;
|
|
if (tcp_do_rfc1323 && (tb.t_flags & TF_RCVD_TSTMP))
|
|
sc->sc_flags |= SCF_TIMESTAMP;
|
|
if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
|
|
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
|
|
sc->sc_requested_s_scale = tb.requested_s_scale;
|
|
sc->sc_request_r_scale = 0;
|
|
while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT &&
|
|
TCP_MAXWIN << sc->sc_request_r_scale <
|
|
so->so_rcv.sb_hiwat)
|
|
sc->sc_request_r_scale++;
|
|
} else {
|
|
sc->sc_requested_s_scale = 15;
|
|
sc->sc_request_r_scale = 15;
|
|
}
|
|
sc->sc_so = so;
|
|
if (syn_cache_respond(sc, m) == 0) {
|
|
syn_cache_insert(sc);
|
|
tcpstat.tcps_sndacks++;
|
|
tcpstat.tcps_sndtotal++;
|
|
} else {
|
|
SYN_CACHE_PUT(sc);
|
|
tcpstat.tcps_sc_dropped++;
|
|
}
|
|
return (1);
|
|
}
|
|
|
|
int
|
|
syn_cache_respond(sc, m)
|
|
struct syn_cache *sc;
|
|
struct mbuf *m;
|
|
{
|
|
struct route *ro = &sc->sc_route4;
|
|
struct rtentry *rt;
|
|
u_int8_t *optp;
|
|
int optlen, error;
|
|
u_int16_t tlen;
|
|
struct ip *ip = NULL;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6 = NULL;
|
|
#endif
|
|
struct tcphdr *th;
|
|
u_int hlen;
|
|
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
hlen = sizeof(struct ip);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
hlen = sizeof(struct ip6_hdr);
|
|
break;
|
|
#endif
|
|
default:
|
|
if (m)
|
|
m_freem(m);
|
|
return EAFNOSUPPORT;
|
|
}
|
|
|
|
/* Compute the size of the TCP options. */
|
|
optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) +
|
|
((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0);
|
|
|
|
tlen = hlen + sizeof(struct tcphdr) + optlen;
|
|
|
|
/*
|
|
* Create the IP+TCP header from scratch. Reuse the received mbuf
|
|
* if possible.
|
|
*/
|
|
if (m != NULL) {
|
|
m_freem(m->m_next);
|
|
m->m_next = NULL;
|
|
MRESETDATA(m);
|
|
} else {
|
|
MGETHDR(m, M_DONTWAIT, MT_DATA);
|
|
if (m == NULL)
|
|
return (ENOBUFS);
|
|
}
|
|
|
|
/* Fixup the mbuf. */
|
|
m->m_data += max_linkhdr;
|
|
m->m_len = m->m_pkthdr.len = tlen;
|
|
#ifdef IPSEC
|
|
/* use IPsec policy on listening socket, on SYN ACK */
|
|
m->m_pkthdr.rcvif = (struct ifnet *)sc->sc_so;
|
|
#else
|
|
m->m_pkthdr.rcvif = NULL;
|
|
#endif
|
|
memset(mtod(m, u_char *), 0, tlen);
|
|
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
ip = mtod(m, struct ip *);
|
|
ip->ip_dst = sc->sc_src.sin.sin_addr;
|
|
ip->ip_src = sc->sc_dst.sin.sin_addr;
|
|
ip->ip_p = IPPROTO_TCP;
|
|
th = (struct tcphdr *)(ip + 1);
|
|
th->th_dport = sc->sc_src.sin.sin_port;
|
|
th->th_sport = sc->sc_dst.sin.sin_port;
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
ip6->ip6_dst = sc->sc_src.sin6.sin6_addr;
|
|
ip6->ip6_src = sc->sc_dst.sin6.sin6_addr;
|
|
ip6->ip6_nxt = IPPROTO_TCP;
|
|
/* ip6_plen will be updated in ip6_output() */
|
|
th = (struct tcphdr *)(ip6 + 1);
|
|
th->th_dport = sc->sc_src.sin6.sin6_port;
|
|
th->th_sport = sc->sc_dst.sin6.sin6_port;
|
|
break;
|
|
#endif
|
|
default:
|
|
th = NULL;
|
|
}
|
|
|
|
th->th_seq = htonl(sc->sc_iss);
|
|
th->th_ack = htonl(sc->sc_irs + 1);
|
|
th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
|
|
th->th_flags = TH_SYN|TH_ACK;
|
|
th->th_win = htons(sc->sc_win);
|
|
/* th_sum already 0 */
|
|
/* th_urp already 0 */
|
|
|
|
/* Tack on the TCP options. */
|
|
optp = (u_int8_t *)(th + 1);
|
|
*optp++ = TCPOPT_MAXSEG;
|
|
*optp++ = 4;
|
|
*optp++ = (sc->sc_ourmaxseg >> 8) & 0xff;
|
|
*optp++ = sc->sc_ourmaxseg & 0xff;
|
|
|
|
if (sc->sc_request_r_scale != 15) {
|
|
*((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 |
|
|
TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 |
|
|
sc->sc_request_r_scale);
|
|
optp += 4;
|
|
}
|
|
|
|
if (sc->sc_flags & SCF_TIMESTAMP) {
|
|
u_int32_t *lp = (u_int32_t *)(optp);
|
|
/* Form timestamp option as shown in appendix A of RFC 1323. */
|
|
*lp++ = htonl(TCPOPT_TSTAMP_HDR);
|
|
*lp++ = htonl(tcp_now);
|
|
*lp = htonl(sc->sc_timestamp);
|
|
optp += TCPOLEN_TSTAMP_APPA;
|
|
}
|
|
|
|
/* Compute the packet's checksum. */
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
ip->ip_len = htons(tlen - hlen);
|
|
th->th_sum = 0;
|
|
th->th_sum = in_cksum(m, tlen);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6->ip6_plen = htons(tlen - hlen);
|
|
th->th_sum = 0;
|
|
th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
|
|
break;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Fill in some straggling IP bits. Note the stack expects
|
|
* ip_len to be in host order, for convenience.
|
|
*/
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
ip->ip_len = tlen;
|
|
ip->ip_ttl = ip_defttl;
|
|
/* XXX tos? */
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6->ip6_vfc = IPV6_VERSION;
|
|
ip6->ip6_plen = htons(tlen - hlen);
|
|
ip6->ip6_hlim = ip6_defhlim;
|
|
/* XXX flowlabel? */
|
|
break;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* If we're doing Path MTU discovery, we need to set DF unless
|
|
* the route's MTU is locked. If we don't yet know the route,
|
|
* look it up now. We will copy this reference to the inpcb
|
|
* when we finish creating the connection.
|
|
*/
|
|
if ((rt = ro->ro_rt) == NULL || (rt->rt_flags & RTF_UP) == 0) {
|
|
if (ro->ro_rt != NULL) {
|
|
RTFREE(ro->ro_rt);
|
|
ro->ro_rt = NULL;
|
|
}
|
|
bcopy(&sc->sc_src, &ro->ro_dst, sc->sc_src.sa.sa_len);
|
|
rtalloc(ro);
|
|
if ((rt = ro->ro_rt) == NULL) {
|
|
m_freem(m);
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
ipstat.ips_noroute++;
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6stat.ip6s_noroute++;
|
|
break;
|
|
#endif
|
|
}
|
|
return (EHOSTUNREACH);
|
|
}
|
|
}
|
|
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
if (ip_mtudisc != 0 && (rt->rt_rmx.rmx_locks & RTV_MTU) == 0)
|
|
ip->ip_off |= IP_DF;
|
|
|
|
/* ...and send it off! */
|
|
error = ip_output(m, sc->sc_ipopts, ro, 0, NULL);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro,
|
|
0, NULL);
|
|
break;
|
|
#endif
|
|
default:
|
|
error = EAFNOSUPPORT;
|
|
break;
|
|
}
|
|
return (error);
|
|
}
|