4642 lines
119 KiB
C
4642 lines
119 KiB
C
/* $NetBSD: tcp_input.c,v 1.431 2021/08/09 19:57:58 andvar Exp $ */
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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 1.1 (NRL) 17 January 1995
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*
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* NRL grants permission for redistribution and use in source and binary
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* forms, with or without modification, of the software and documentation
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* created at NRL provided that the following conditions are met:
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*
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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 acknowledgements:
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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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* This product includes software developed at the Information
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* Technology Division, US Naval Research Laboratory.
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* 4. Neither the name of the NRL 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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* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
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* 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
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* The views and conclusions contained in the software and documentation
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* are those of the authors and should not be interpreted as representing
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* official policies, either expressed or implied, of the US Naval
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* Research Laboratory (NRL).
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*/
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/*-
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* Copyright (c) 1997, 1998, 1999, 2001, 2005, 2006,
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* 2011 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 Coyote Point Systems, Inc.
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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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* This code is derived from software contributed to The NetBSD Foundation
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* by Charles M. Hannum.
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* This code is derived from software contributed to The NetBSD Foundation
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* by Rui Paulo.
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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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*
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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. 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 <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.431 2021/08/09 19:57:58 andvar Exp $");
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#ifdef _KERNEL_OPT
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#include "opt_inet.h"
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#include "opt_ipsec.h"
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#include "opt_inet_csum.h"
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#include "opt_tcp_debug.h"
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#endif
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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 <sys/kernel.h>
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#ifdef TCP_SIGNATURE
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#include <sys/md5.h>
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#endif
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#include <sys/lwp.h> /* for lwp0 */
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#include <sys/cprng.h>
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#include <net/if.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/in_var.h>
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#include <netinet/ip_var.h>
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#include <netinet/in_offload.h>
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#if NARP > 0
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#include <netinet/if_inarp.h>
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#endif
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#ifdef INET6
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#include <netinet/ip6.h>
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#include <netinet6/ip6_var.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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#include <netinet6/nd6.h>
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#ifdef TCP_SIGNATURE
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#include <netinet6/scope6_var.h>
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#endif
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#endif
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#ifndef INET6
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#include <netinet/ip6.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/tcp_private.h>
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#include <netinet/tcp_congctl.h>
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#include <netinet/tcp_debug.h>
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#ifdef INET6
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#include "faith.h"
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#if defined(NFAITH) && NFAITH > 0
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#include <net/if_faith.h>
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#endif
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#endif
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#ifdef IPSEC
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#include <netipsec/ipsec.h>
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#include <netipsec/key.h>
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#ifdef INET6
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#include <netipsec/ipsec6.h>
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#endif
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#endif /* IPSEC*/
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#include <netinet/tcp_vtw.h>
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int tcprexmtthresh = 3;
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int tcp_log_refused;
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int tcp_do_autorcvbuf = 1;
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int tcp_autorcvbuf_inc = 16 * 1024;
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int tcp_autorcvbuf_max = 256 * 1024;
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int tcp_msl = (TCPTV_MSL / PR_SLOWHZ);
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static int tcp_rst_ppslim_count = 0;
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static struct timeval tcp_rst_ppslim_last;
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static int tcp_ackdrop_ppslim_count = 0;
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static struct timeval tcp_ackdrop_ppslim_last;
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static void syn_cache_timer(void *);
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#define TCP_PAWS_IDLE (24U * 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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* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint.
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*/
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static void
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nd_hint(struct tcpcb *tp)
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{
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struct route *ro = NULL;
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struct rtentry *rt;
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if (tp == NULL)
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return;
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switch (tp->t_family) {
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#if NARP > 0
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case AF_INET:
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if (tp->t_inpcb != NULL)
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ro = &tp->t_inpcb->inp_route;
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break;
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#endif
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#ifdef INET6
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case AF_INET6:
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if (tp->t_in6pcb != NULL)
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ro = &tp->t_in6pcb->in6p_route;
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break;
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#endif
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}
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if (ro == NULL)
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return;
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rt = rtcache_validate(ro);
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if (rt == NULL)
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return;
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switch (tp->t_family) {
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#if NARP > 0
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case AF_INET:
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arp_nud_hint(rt);
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break;
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#endif
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#ifdef INET6
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case AF_INET6:
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nd6_nud_hint(rt);
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break;
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#endif
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}
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rtcache_unref(rt, ro);
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}
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/*
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* 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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static void
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tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th)
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{
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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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}
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static void
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icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked)
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{
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/*
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* If we had a pending ICMP message that refers to data that have
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* just been acknowledged, disregard the recorded ICMP message.
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*/
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if ((tp->t_flags & TF_PMTUD_PEND) &&
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SEQ_GT(th->th_ack, tp->t_pmtud_th_seq))
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tp->t_flags &= ~TF_PMTUD_PEND;
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/*
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* Keep track of the largest chunk of data
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* acknowledged since last PMTU update
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*/
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if (tp->t_pmtud_mss_acked < acked)
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tp->t_pmtud_mss_acked = acked;
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}
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/*
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* Convert TCP protocol fields to host order for easier processing.
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*/
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static void
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tcp_fields_to_host(struct tcphdr *th)
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{
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NTOHL(th->th_seq);
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NTOHL(th->th_ack);
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NTOHS(th->th_win);
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NTOHS(th->th_urp);
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}
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/*
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* ... and reverse the above.
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*/
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static void
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tcp_fields_to_net(struct tcphdr *th)
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{
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HTONL(th->th_seq);
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HTONL(th->th_ack);
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HTONS(th->th_win);
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HTONS(th->th_urp);
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}
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static void
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tcp_urp_drop(struct tcphdr *th, int todrop, int *tiflags)
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{
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if (th->th_urp > todrop) {
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th->th_urp -= todrop;
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} else {
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*tiflags &= ~TH_URG;
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th->th_urp = 0;
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}
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}
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#ifdef TCP_CSUM_COUNTERS
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#include <sys/device.h>
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extern struct evcnt tcp_hwcsum_ok;
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extern struct evcnt tcp_hwcsum_bad;
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extern struct evcnt tcp_hwcsum_data;
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extern struct evcnt tcp_swcsum;
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#if defined(INET6)
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extern struct evcnt tcp6_hwcsum_ok;
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extern struct evcnt tcp6_hwcsum_bad;
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extern struct evcnt tcp6_hwcsum_data;
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extern struct evcnt tcp6_swcsum;
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#endif /* defined(INET6) */
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#define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++
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#else
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#define TCP_CSUM_COUNTER_INCR(ev) /* nothing */
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#endif /* TCP_CSUM_COUNTERS */
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#ifdef TCP_REASS_COUNTERS
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#include <sys/device.h>
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extern struct evcnt tcp_reass_;
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extern struct evcnt tcp_reass_empty;
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extern struct evcnt tcp_reass_iteration[8];
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extern struct evcnt tcp_reass_prependfirst;
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extern struct evcnt tcp_reass_prepend;
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extern struct evcnt tcp_reass_insert;
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extern struct evcnt tcp_reass_inserttail;
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extern struct evcnt tcp_reass_append;
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extern struct evcnt tcp_reass_appendtail;
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extern struct evcnt tcp_reass_overlaptail;
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extern struct evcnt tcp_reass_overlapfront;
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extern struct evcnt tcp_reass_segdup;
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extern struct evcnt tcp_reass_fragdup;
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#define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++
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#else
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#define TCP_REASS_COUNTER_INCR(ev) /* nothing */
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#endif /* TCP_REASS_COUNTERS */
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static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *,
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int);
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static int tcp_dooptions(struct tcpcb *, const u_char *, int,
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struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *);
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static void tcp4_log_refused(const struct ip *, const struct tcphdr *);
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#ifdef INET6
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static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *);
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#endif
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#if defined(MBUFTRACE)
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struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass");
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#endif /* defined(MBUFTRACE) */
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static struct pool tcpipqent_pool;
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void
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tcpipqent_init(void)
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{
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pool_init(&tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl",
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NULL, IPL_VM);
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}
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struct ipqent *
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tcpipqent_alloc(void)
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{
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struct ipqent *ipqe;
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int s;
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s = splvm();
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ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT);
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splx(s);
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return ipqe;
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}
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void
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tcpipqent_free(struct ipqent *ipqe)
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{
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int s;
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s = splvm();
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pool_put(&tcpipqent_pool, ipqe);
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splx(s);
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}
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/*
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* Insert segment ti into reassembly queue of tcp with
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* control block tp. Return TH_FIN if reassembly now includes
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* a segment with FIN.
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*/
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static int
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tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int tlen)
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{
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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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#ifdef TCP_REASS_COUNTERS
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u_int count = 0;
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#endif
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uint64_t *tcps;
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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;
|
|
#endif
|
|
|
|
TCP_REASS_LOCK_CHECK(tp);
|
|
|
|
/*
|
|
* Call with th==NULL after become established to
|
|
* force pre-ESTABLISHED data up to user socket.
|
|
*/
|
|
if (th == NULL)
|
|
goto present;
|
|
|
|
m_claimm(m, &tcp_reass_mowner);
|
|
|
|
rcvoobyte = tlen;
|
|
/*
|
|
* Copy these to local variables because the TCP header gets munged
|
|
* while we are collapsing mbufs.
|
|
*/
|
|
pkt_seq = th->th_seq;
|
|
pkt_len = tlen;
|
|
pkt_flags = th->th_flags;
|
|
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_);
|
|
|
|
if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) {
|
|
/*
|
|
* When we miss a packet, the vast majority of time we get
|
|
* packets that follow it in order. So optimize for that.
|
|
*/
|
|
if (pkt_seq == p->ipqe_seq + p->ipqe_len) {
|
|
p->ipqe_len += pkt_len;
|
|
p->ipqe_flags |= pkt_flags;
|
|
m_cat(p->ipqe_m, m);
|
|
m = NULL;
|
|
tiqe = p;
|
|
TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq);
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail);
|
|
goto skip_replacement;
|
|
}
|
|
/*
|
|
* While we're here, if the pkt is completely beyond
|
|
* anything we have, just insert it at the tail.
|
|
*/
|
|
if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) {
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail);
|
|
goto insert_it;
|
|
}
|
|
}
|
|
|
|
q = TAILQ_FIRST(&tp->segq);
|
|
|
|
if (q != NULL) {
|
|
/*
|
|
* If this segment immediately precedes the first out-of-order
|
|
* block, simply slap the segment in front of it and (mostly)
|
|
* skip the complicated logic.
|
|
*/
|
|
if (pkt_seq + pkt_len == q->ipqe_seq) {
|
|
q->ipqe_seq = pkt_seq;
|
|
q->ipqe_len += pkt_len;
|
|
q->ipqe_flags |= pkt_flags;
|
|
m_cat(m, q->ipqe_m);
|
|
q->ipqe_m = m;
|
|
tiqe = q;
|
|
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst);
|
|
goto skip_replacement;
|
|
}
|
|
} else {
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_empty);
|
|
}
|
|
|
|
/*
|
|
* Find a segment which begins after this one does.
|
|
*/
|
|
for (p = NULL; q != NULL; q = nq) {
|
|
nq = TAILQ_NEXT(q, ipqe_q);
|
|
#ifdef TCP_REASS_COUNTERS
|
|
count++;
|
|
#endif
|
|
|
|
/*
|
|
* If the received segment is just right after this
|
|
* fragment, merge the two together and then check
|
|
* for further overlaps.
|
|
*/
|
|
if (q->ipqe_seq + q->ipqe_len == pkt_seq) {
|
|
pkt_len += q->ipqe_len;
|
|
pkt_flags |= q->ipqe_flags;
|
|
pkt_seq = q->ipqe_seq;
|
|
m_cat(q->ipqe_m, m);
|
|
m = q->ipqe_m;
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_append);
|
|
goto free_ipqe;
|
|
}
|
|
|
|
/*
|
|
* If the received segment is completely past this
|
|
* fragment, we need to go to the next fragment.
|
|
*/
|
|
if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) {
|
|
p = q;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* If the fragment is past the received segment,
|
|
* it (or any following) can't be concatenated.
|
|
*/
|
|
if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) {
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_insert);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* We've received all the data in this segment before.
|
|
* Mark it as a duplicate and return.
|
|
*/
|
|
if (SEQ_LEQ(q->ipqe_seq, pkt_seq) &&
|
|
SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) {
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVDUPPACK]++;
|
|
tcps[TCP_STAT_RCVDUPBYTE] += pkt_len;
|
|
TCP_STAT_PUTREF();
|
|
tcp_new_dsack(tp, pkt_seq, pkt_len);
|
|
m_freem(m);
|
|
if (tiqe != NULL) {
|
|
tcpipqent_free(tiqe);
|
|
}
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_segdup);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Received segment completely overlaps this fragment
|
|
* so we drop the fragment (this keeps the temporal
|
|
* ordering of segments correct).
|
|
*/
|
|
if (SEQ_GEQ(q->ipqe_seq, pkt_seq) &&
|
|
SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) {
|
|
rcvpartdupbyte += q->ipqe_len;
|
|
m_freem(q->ipqe_m);
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup);
|
|
goto free_ipqe;
|
|
}
|
|
|
|
/*
|
|
* Received segment extends past the end of the fragment.
|
|
* Drop the overlapping bytes, merge the fragment and
|
|
* segment, and treat as a longer received packet.
|
|
*/
|
|
if (SEQ_LT(q->ipqe_seq, pkt_seq) &&
|
|
SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) {
|
|
int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq;
|
|
m_adj(m, overlap);
|
|
rcvpartdupbyte += overlap;
|
|
m_cat(q->ipqe_m, m);
|
|
m = q->ipqe_m;
|
|
pkt_seq = q->ipqe_seq;
|
|
pkt_len += q->ipqe_len - overlap;
|
|
rcvoobyte -= overlap;
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail);
|
|
goto free_ipqe;
|
|
}
|
|
|
|
/*
|
|
* Received segment extends past the front of the fragment.
|
|
* Drop the overlapping bytes on the received packet. The
|
|
* packet will then be concatenated with this fragment a
|
|
* bit later.
|
|
*/
|
|
if (SEQ_GT(q->ipqe_seq, pkt_seq) &&
|
|
SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) {
|
|
int overlap = pkt_seq + pkt_len - q->ipqe_seq;
|
|
m_adj(m, -overlap);
|
|
pkt_len -= overlap;
|
|
rcvpartdupbyte += overlap;
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront);
|
|
rcvoobyte -= overlap;
|
|
}
|
|
|
|
/*
|
|
* If the received segment immediately precedes this
|
|
* fragment then tack the fragment onto this segment
|
|
* and reinsert the data.
|
|
*/
|
|
if (q->ipqe_seq == pkt_seq + pkt_len) {
|
|
pkt_len += q->ipqe_len;
|
|
pkt_flags |= q->ipqe_flags;
|
|
m_cat(m, q->ipqe_m);
|
|
TAILQ_REMOVE(&tp->segq, q, ipqe_q);
|
|
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
|
|
tp->t_segqlen--;
|
|
KASSERT(tp->t_segqlen >= 0);
|
|
KASSERT(tp->t_segqlen != 0 ||
|
|
(TAILQ_EMPTY(&tp->segq) &&
|
|
TAILQ_EMPTY(&tp->timeq)));
|
|
if (tiqe == NULL) {
|
|
tiqe = q;
|
|
} else {
|
|
tcpipqent_free(q);
|
|
}
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_prepend);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If the fragment is before the segment, remember it.
|
|
* When this loop is terminated, p will contain the
|
|
* pointer to the fragment that is right before the
|
|
* received segment.
|
|
*/
|
|
if (SEQ_LEQ(q->ipqe_seq, pkt_seq))
|
|
p = q;
|
|
|
|
continue;
|
|
|
|
/*
|
|
* This is a common operation. It also will allow
|
|
* to save doing a malloc/free in most instances.
|
|
*/
|
|
free_ipqe:
|
|
TAILQ_REMOVE(&tp->segq, q, ipqe_q);
|
|
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
|
|
tp->t_segqlen--;
|
|
KASSERT(tp->t_segqlen >= 0);
|
|
KASSERT(tp->t_segqlen != 0 ||
|
|
(TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq)));
|
|
if (tiqe == NULL) {
|
|
tiqe = q;
|
|
} else {
|
|
tcpipqent_free(q);
|
|
}
|
|
}
|
|
|
|
#ifdef TCP_REASS_COUNTERS
|
|
if (count > 7)
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]);
|
|
else if (count > 0)
|
|
TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]);
|
|
#endif
|
|
|
|
insert_it:
|
|
/*
|
|
* Allocate a new queue entry (block) since the received segment
|
|
* did not collapse onto any other out-of-order block. If it had
|
|
* collapsed, tiqe would not be NULL and we would be reusing it.
|
|
*
|
|
* If the allocation fails, drop the packet.
|
|
*/
|
|
if (tiqe == NULL) {
|
|
tiqe = tcpipqent_alloc();
|
|
if (tiqe == NULL) {
|
|
TCP_STATINC(TCP_STAT_RCVMEMDROP);
|
|
m_freem(m);
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Update the counters.
|
|
*/
|
|
tp->t_rcvoopack++;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVOOPACK]++;
|
|
tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte;
|
|
if (rcvpartdupbyte) {
|
|
tcps[TCP_STAT_RCVPARTDUPPACK]++;
|
|
tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte;
|
|
}
|
|
TCP_STAT_PUTREF();
|
|
|
|
/*
|
|
* 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) {
|
|
TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q);
|
|
} else {
|
|
TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q);
|
|
}
|
|
tp->t_segqlen++;
|
|
|
|
skip_replacement:
|
|
TAILQ_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)
|
|
goto out;
|
|
q = TAILQ_FIRST(&tp->segq);
|
|
if (q == NULL || q->ipqe_seq != tp->rcv_nxt)
|
|
goto out;
|
|
if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len)
|
|
goto out;
|
|
|
|
tp->rcv_nxt += q->ipqe_len;
|
|
pkt_flags = q->ipqe_flags & TH_FIN;
|
|
nd_hint(tp);
|
|
|
|
TAILQ_REMOVE(&tp->segq, q, ipqe_q);
|
|
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
|
|
tp->t_segqlen--;
|
|
KASSERT(tp->t_segqlen >= 0);
|
|
KASSERT(tp->t_segqlen != 0 ||
|
|
(TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq)));
|
|
if (so->so_state & SS_CANTRCVMORE)
|
|
m_freem(q->ipqe_m);
|
|
else
|
|
sbappendstream(&so->so_rcv, q->ipqe_m);
|
|
tcpipqent_free(q);
|
|
TCP_REASS_UNLOCK(tp);
|
|
sorwakeup(so);
|
|
return pkt_flags;
|
|
|
|
out:
|
|
TCP_REASS_UNLOCK(tp);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef INET6
|
|
int
|
|
tcp6_input(struct mbuf **mp, int *offp, int proto)
|
|
{
|
|
struct mbuf *m = *mp;
|
|
|
|
/*
|
|
* draft-itojun-ipv6-tcp-to-anycast
|
|
* better place to put this in?
|
|
*/
|
|
if (m->m_flags & M_ANYCAST6) {
|
|
struct ip6_hdr *ip6;
|
|
if (m->m_len < sizeof(struct ip6_hdr)) {
|
|
if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
|
|
TCP_STATINC(TCP_STAT_RCVSHORT);
|
|
return IPPROTO_DONE;
|
|
}
|
|
}
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
|
|
(char *)&ip6->ip6_dst - (char *)ip6);
|
|
return IPPROTO_DONE;
|
|
}
|
|
|
|
tcp_input(m, *offp, proto);
|
|
return IPPROTO_DONE;
|
|
}
|
|
#endif
|
|
|
|
static void
|
|
tcp4_log_refused(const struct ip *ip, const struct tcphdr *th)
|
|
{
|
|
char src[INET_ADDRSTRLEN];
|
|
char dst[INET_ADDRSTRLEN];
|
|
|
|
if (ip) {
|
|
in_print(src, sizeof(src), &ip->ip_src);
|
|
in_print(dst, sizeof(dst), &ip->ip_dst);
|
|
} else {
|
|
strlcpy(src, "(unknown)", sizeof(src));
|
|
strlcpy(dst, "(unknown)", sizeof(dst));
|
|
}
|
|
log(LOG_INFO,
|
|
"Connection attempt to TCP %s:%d from %s:%d\n",
|
|
dst, ntohs(th->th_dport),
|
|
src, ntohs(th->th_sport));
|
|
}
|
|
|
|
#ifdef INET6
|
|
static void
|
|
tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th)
|
|
{
|
|
char src[INET6_ADDRSTRLEN];
|
|
char dst[INET6_ADDRSTRLEN];
|
|
|
|
if (ip6) {
|
|
in6_print(src, sizeof(src), &ip6->ip6_src);
|
|
in6_print(dst, sizeof(dst), &ip6->ip6_dst);
|
|
} else {
|
|
strlcpy(src, "(unknown v6)", sizeof(src));
|
|
strlcpy(dst, "(unknown v6)", sizeof(dst));
|
|
}
|
|
log(LOG_INFO,
|
|
"Connection attempt to TCP [%s]:%d from [%s]:%d\n",
|
|
dst, ntohs(th->th_dport),
|
|
src, ntohs(th->th_sport));
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Checksum extended TCP header and data.
|
|
*/
|
|
int
|
|
tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th,
|
|
int toff, int off, int tlen)
|
|
{
|
|
struct ifnet *rcvif;
|
|
int s;
|
|
|
|
/*
|
|
* XXX it's better to record and check if this mbuf is
|
|
* already checked.
|
|
*/
|
|
|
|
rcvif = m_get_rcvif(m, &s);
|
|
if (__predict_false(rcvif == NULL))
|
|
goto badcsum; /* XXX */
|
|
|
|
switch (af) {
|
|
case AF_INET:
|
|
switch (m->m_pkthdr.csum_flags &
|
|
((rcvif->if_csum_flags_rx & M_CSUM_TCPv4) |
|
|
M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) {
|
|
case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD:
|
|
TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad);
|
|
goto badcsum;
|
|
|
|
case M_CSUM_TCPv4|M_CSUM_DATA: {
|
|
u_int32_t hw_csum = m->m_pkthdr.csum_data;
|
|
|
|
TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data);
|
|
if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) {
|
|
const struct ip *ip =
|
|
mtod(m, const struct ip *);
|
|
|
|
hw_csum = in_cksum_phdr(ip->ip_src.s_addr,
|
|
ip->ip_dst.s_addr,
|
|
htons(hw_csum + tlen + off + IPPROTO_TCP));
|
|
}
|
|
if ((hw_csum ^ 0xffff) != 0)
|
|
goto badcsum;
|
|
break;
|
|
}
|
|
|
|
case M_CSUM_TCPv4:
|
|
/* Checksum was okay. */
|
|
TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok);
|
|
break;
|
|
|
|
default:
|
|
/*
|
|
* Must compute it ourselves. Maybe skip checksum
|
|
* on loopback interfaces.
|
|
*/
|
|
if (__predict_true(!(rcvif->if_flags & IFF_LOOPBACK) ||
|
|
tcp_do_loopback_cksum)) {
|
|
TCP_CSUM_COUNTER_INCR(&tcp_swcsum);
|
|
if (in4_cksum(m, IPPROTO_TCP, toff,
|
|
tlen + off) != 0)
|
|
goto badcsum;
|
|
}
|
|
break;
|
|
}
|
|
break;
|
|
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
switch (m->m_pkthdr.csum_flags &
|
|
((rcvif->if_csum_flags_rx & M_CSUM_TCPv6) |
|
|
M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) {
|
|
case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD:
|
|
TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad);
|
|
goto badcsum;
|
|
|
|
#if 0 /* notyet */
|
|
case M_CSUM_TCPv6|M_CSUM_DATA:
|
|
#endif
|
|
|
|
case M_CSUM_TCPv6:
|
|
/* Checksum was okay. */
|
|
TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok);
|
|
break;
|
|
|
|
default:
|
|
/*
|
|
* Must compute it ourselves. Maybe skip checksum
|
|
* on loopback interfaces.
|
|
*/
|
|
if (__predict_true((m->m_flags & M_LOOP) == 0 ||
|
|
tcp_do_loopback_cksum)) {
|
|
TCP_CSUM_COUNTER_INCR(&tcp6_swcsum);
|
|
if (in6_cksum(m, IPPROTO_TCP, toff,
|
|
tlen + off) != 0)
|
|
goto badcsum;
|
|
}
|
|
}
|
|
break;
|
|
#endif /* INET6 */
|
|
}
|
|
m_put_rcvif(rcvif, &s);
|
|
|
|
return 0;
|
|
|
|
badcsum:
|
|
m_put_rcvif(rcvif, &s);
|
|
TCP_STATINC(TCP_STAT_RCVBADSUM);
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* When a packet arrives addressed to a vestigial tcpbp, we
|
|
* nevertheless have to respond to it per the spec.
|
|
*
|
|
* This code is duplicated from the one in tcp_input().
|
|
*/
|
|
static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp,
|
|
struct mbuf *m, int tlen)
|
|
{
|
|
int tiflags;
|
|
int todrop;
|
|
uint32_t t_flags = 0;
|
|
uint64_t *tcps;
|
|
|
|
tiflags = th->th_flags;
|
|
todrop = vp->rcv_nxt - th->th_seq;
|
|
|
|
if (todrop > 0) {
|
|
if (tiflags & TH_SYN) {
|
|
tiflags &= ~TH_SYN;
|
|
th->th_seq++;
|
|
tcp_urp_drop(th, 1, &tiflags);
|
|
todrop--;
|
|
}
|
|
if (todrop > tlen ||
|
|
(todrop == tlen && (tiflags & TH_FIN) == 0)) {
|
|
/*
|
|
* Any valid FIN or RST must be to the left of the
|
|
* window. At this point the FIN or RST must be a
|
|
* duplicate or out of sequence; drop it.
|
|
*/
|
|
if (tiflags & TH_RST)
|
|
goto drop;
|
|
tiflags &= ~(TH_FIN|TH_RST);
|
|
|
|
/*
|
|
* Send an ACK to resynchronize and drop any data.
|
|
* But keep on processing for RST or ACK.
|
|
*/
|
|
t_flags |= TF_ACKNOW;
|
|
todrop = tlen;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVDUPPACK] += 1;
|
|
tcps[TCP_STAT_RCVDUPBYTE] += todrop;
|
|
TCP_STAT_PUTREF();
|
|
} else if ((tiflags & TH_RST) &&
|
|
th->th_seq != vp->rcv_nxt) {
|
|
/*
|
|
* Test for reset before adjusting the sequence
|
|
* number for overlapping data.
|
|
*/
|
|
goto dropafterack_ratelim;
|
|
} else {
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVPARTDUPPACK] += 1;
|
|
tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop;
|
|
TCP_STAT_PUTREF();
|
|
}
|
|
|
|
// tcp_new_dsack(tp, th->th_seq, todrop);
|
|
// hdroptlen += todrop; /*drop from head afterwards*/
|
|
|
|
th->th_seq += todrop;
|
|
tlen -= todrop;
|
|
tcp_urp_drop(th, todrop, &tiflags);
|
|
}
|
|
|
|
/*
|
|
* If new data are received on a connection after the
|
|
* user processes are gone, then RST the other end.
|
|
*/
|
|
if (tlen) {
|
|
TCP_STATINC(TCP_STAT_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) - (vp->rcv_nxt + vp->rcv_wnd);
|
|
|
|
if (todrop > 0) {
|
|
TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN);
|
|
if (todrop >= tlen) {
|
|
/*
|
|
* The segment actually starts after the window.
|
|
* th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen
|
|
* th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0
|
|
* th->th_seq >= vp->rcv_nxt + vp->rcv_wnd
|
|
*/
|
|
TCP_STATADD(TCP_STAT_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) &&
|
|
SEQ_GT(th->th_seq, vp->rcv_nxt)) {
|
|
/*
|
|
* We only support this in the !NOFDREF case, which
|
|
* is to say: not here.
|
|
*/
|
|
goto dropwithreset;
|
|
}
|
|
|
|
/*
|
|
* 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 (if not RST) ack.
|
|
*/
|
|
if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) {
|
|
t_flags |= TF_ACKNOW;
|
|
TCP_STATINC(TCP_STAT_RCVWINPROBE);
|
|
} else {
|
|
goto dropafterack;
|
|
}
|
|
} else {
|
|
TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop);
|
|
}
|
|
m_adj(m, -todrop);
|
|
tlen -= todrop;
|
|
tiflags &= ~(TH_PUSH|TH_FIN);
|
|
}
|
|
|
|
if (tiflags & TH_RST) {
|
|
if (th->th_seq != vp->rcv_nxt)
|
|
goto dropafterack_ratelim;
|
|
|
|
vtw_del(vp->ctl, vp->vtw);
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* If the ACK bit is off we drop the segment and return.
|
|
*/
|
|
if ((tiflags & TH_ACK) == 0) {
|
|
if (t_flags & TF_ACKNOW)
|
|
goto dropafterack;
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* In TIME_WAIT state the only thing that should arrive
|
|
* is a retransmission of the remote FIN. Acknowledge
|
|
* it and restart the finack timer.
|
|
*/
|
|
vtw_restart(vp);
|
|
goto dropafterack;
|
|
|
|
dropafterack:
|
|
/*
|
|
* Generate an ACK dropping incoming segment if it occupies
|
|
* sequence space, where the ACK reflects our state.
|
|
*/
|
|
if (tiflags & TH_RST)
|
|
goto drop;
|
|
goto dropafterack2;
|
|
|
|
dropafterack_ratelim:
|
|
/*
|
|
* We may want to rate-limit ACKs against SYN/RST attack.
|
|
*/
|
|
if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count,
|
|
tcp_ackdrop_ppslim) == 0) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
/* ...fall into dropafterack2... */
|
|
|
|
dropafterack2:
|
|
(void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, TH_ACK);
|
|
return;
|
|
|
|
dropwithreset:
|
|
/*
|
|
* Generate a RST, dropping incoming segment.
|
|
* Make ACK acceptable to originator of segment.
|
|
*/
|
|
if (tiflags & TH_RST)
|
|
goto drop;
|
|
|
|
if (tiflags & TH_ACK) {
|
|
tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST);
|
|
} else {
|
|
if (tiflags & TH_SYN)
|
|
++tlen;
|
|
(void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0,
|
|
TH_RST|TH_ACK);
|
|
}
|
|
return;
|
|
drop:
|
|
m_freem(m);
|
|
}
|
|
|
|
/*
|
|
* TCP input routine, follows pages 65-76 of RFC 793 very closely.
|
|
*/
|
|
void
|
|
tcp_input(struct mbuf *m, int off, int proto)
|
|
{
|
|
struct tcphdr *th;
|
|
struct ip *ip;
|
|
struct inpcb *inp;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6;
|
|
struct in6pcb *in6p;
|
|
#endif
|
|
u_int8_t *optp = NULL;
|
|
int optlen = 0;
|
|
int len, tlen, hdroptlen = 0;
|
|
struct tcpcb *tp = NULL;
|
|
int tiflags;
|
|
struct socket *so = NULL;
|
|
int todrop, acked, ourfinisacked, needoutput = 0;
|
|
bool dupseg;
|
|
#ifdef TCP_DEBUG
|
|
short ostate = 0;
|
|
#endif
|
|
u_long tiwin;
|
|
struct tcp_opt_info opti;
|
|
int thlen, iphlen;
|
|
int af; /* af on the wire */
|
|
struct mbuf *tcp_saveti = NULL;
|
|
uint32_t ts_rtt;
|
|
uint8_t iptos;
|
|
uint64_t *tcps;
|
|
vestigial_inpcb_t vestige;
|
|
|
|
vestige.valid = 0;
|
|
|
|
MCLAIM(m, &tcp_rx_mowner);
|
|
|
|
TCP_STATINC(TCP_STAT_RCVTOTAL);
|
|
|
|
memset(&opti, 0, sizeof(opti));
|
|
opti.ts_present = 0;
|
|
opti.maxseg = 0;
|
|
|
|
/*
|
|
* RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN.
|
|
*
|
|
* TCP is, by definition, unicast, so we reject all
|
|
* multicast outright.
|
|
*
|
|
* Note, there are additional src/dst address checks in
|
|
* the AF-specific code below.
|
|
*/
|
|
if (m->m_flags & (M_BCAST|M_MCAST)) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
#ifdef INET6
|
|
if (m->m_flags & M_ANYCAST6) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
#endif
|
|
|
|
M_REGION_GET(th, struct tcphdr *, m, off, sizeof(struct tcphdr));
|
|
if (th == NULL) {
|
|
TCP_STATINC(TCP_STAT_RCVSHORT);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Enforce alignment requirements that are violated in
|
|
* some cases, see kern/50766 for details.
|
|
*/
|
|
if (ACCESSIBLE_POINTER(th, struct tcphdr) == 0) {
|
|
m = m_copyup(m, off + sizeof(struct tcphdr), 0);
|
|
if (m == NULL) {
|
|
TCP_STATINC(TCP_STAT_RCVSHORT);
|
|
return;
|
|
}
|
|
th = (struct tcphdr *)(mtod(m, char *) + off);
|
|
}
|
|
KASSERT(ACCESSIBLE_POINTER(th, struct tcphdr));
|
|
|
|
/*
|
|
* Get IP and TCP header.
|
|
* Note: IP leaves IP header in first mbuf.
|
|
*/
|
|
ip = mtod(m, struct ip *);
|
|
#ifdef INET6
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
#endif
|
|
switch (ip->ip_v) {
|
|
case 4:
|
|
af = AF_INET;
|
|
iphlen = sizeof(struct ip);
|
|
|
|
if (IN_MULTICAST(ip->ip_dst.s_addr) ||
|
|
in_broadcast(ip->ip_dst, m_get_rcvif_NOMPSAFE(m)))
|
|
goto drop;
|
|
|
|
/* We do the checksum after PCB lookup... */
|
|
len = ntohs(ip->ip_len);
|
|
tlen = len - off;
|
|
iptos = ip->ip_tos;
|
|
break;
|
|
#ifdef INET6
|
|
case 6:
|
|
iphlen = sizeof(struct ip6_hdr);
|
|
af = AF_INET6;
|
|
|
|
/*
|
|
* Be proactive about unspecified IPv6 address in source.
|
|
* As we use all-zero to indicate unbounded/unconnected pcb,
|
|
* unspecified IPv6 address can be used to confuse us.
|
|
*
|
|
* Note that packets with unspecified IPv6 destination is
|
|
* already dropped in ip6_input.
|
|
*/
|
|
if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* Make sure destination address is not multicast.
|
|
* Source address checked in ip6_input().
|
|
*/
|
|
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
|
|
/* We do the checksum after PCB lookup... */
|
|
len = m->m_pkthdr.len;
|
|
tlen = len - off;
|
|
iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
|
|
break;
|
|
#endif
|
|
default:
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
|
|
|
|
/*
|
|
* Check that TCP offset makes sense, pull out TCP options and
|
|
* adjust length.
|
|
*/
|
|
thlen = th->th_off << 2;
|
|
if (thlen < sizeof(struct tcphdr) || thlen > tlen) {
|
|
TCP_STATINC(TCP_STAT_RCVBADOFF);
|
|
goto drop;
|
|
}
|
|
tlen -= thlen;
|
|
|
|
if (thlen > sizeof(struct tcphdr)) {
|
|
M_REGION_GET(th, struct tcphdr *, m, off, thlen);
|
|
if (th == NULL) {
|
|
TCP_STATINC(TCP_STAT_RCVSHORT);
|
|
return;
|
|
}
|
|
KASSERT(ACCESSIBLE_POINTER(th, struct tcphdr));
|
|
optlen = thlen - sizeof(struct tcphdr);
|
|
optp = ((u_int8_t *)th) + sizeof(struct tcphdr);
|
|
|
|
/*
|
|
* Do quick retrieval of timestamp options.
|
|
*
|
|
* If timestamp is the only option and it's formatted as
|
|
* recommended in RFC 1323 appendix A, we quickly get the
|
|
* values now and don't bother calling tcp_dooptions(),
|
|
* etc.
|
|
*/
|
|
if ((optlen == TCPOLEN_TSTAMP_APPA ||
|
|
(optlen > TCPOLEN_TSTAMP_APPA &&
|
|
optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) &&
|
|
be32dec(optp) == TCPOPT_TSTAMP_HDR &&
|
|
(th->th_flags & TH_SYN) == 0) {
|
|
opti.ts_present = 1;
|
|
opti.ts_val = be32dec(optp + 4);
|
|
opti.ts_ecr = be32dec(optp + 8);
|
|
optp = NULL; /* we've parsed the options */
|
|
}
|
|
}
|
|
tiflags = th->th_flags;
|
|
|
|
/*
|
|
* Checksum extended TCP header and data
|
|
*/
|
|
if (tcp_input_checksum(af, m, th, off, thlen, tlen))
|
|
goto badcsum;
|
|
|
|
/*
|
|
* 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, &vestige);
|
|
if (inp == NULL && !vestige.valid) {
|
|
TCP_STATINC(TCP_STAT_PCBHASHMISS);
|
|
inp = in_pcblookup_bind(&tcbtable, ip->ip_dst,
|
|
th->th_dport);
|
|
}
|
|
#ifdef INET6
|
|
if (inp == NULL && !vestige.valid) {
|
|
struct in6_addr s, d;
|
|
|
|
/* mapped addr case */
|
|
in6_in_2_v4mapin6(&ip->ip_src, &s);
|
|
in6_in_2_v4mapin6(&ip->ip_dst, &d);
|
|
in6p = in6_pcblookup_connect(&tcbtable, &s,
|
|
th->th_sport, &d, th->th_dport, 0, &vestige);
|
|
if (in6p == 0 && !vestige.valid) {
|
|
TCP_STATINC(TCP_STAT_PCBHASHMISS);
|
|
in6p = in6_pcblookup_bind(&tcbtable, &d,
|
|
th->th_dport, 0);
|
|
}
|
|
}
|
|
#endif
|
|
#ifndef INET6
|
|
if (inp == NULL && !vestige.valid)
|
|
#else
|
|
if (inp == NULL && in6p == NULL && !vestige.valid)
|
|
#endif
|
|
{
|
|
TCP_STATINC(TCP_STAT_NOPORT);
|
|
if (tcp_log_refused &&
|
|
(tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) {
|
|
tcp4_log_refused(ip, th);
|
|
}
|
|
tcp_fields_to_host(th);
|
|
goto dropwithreset_ratelim;
|
|
}
|
|
#if defined(IPSEC)
|
|
if (ipsec_used) {
|
|
if (inp && ipsec_in_reject(m, inp)) {
|
|
goto drop;
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p && ipsec_in_reject(m, in6p)) {
|
|
goto drop;
|
|
}
|
|
#endif
|
|
}
|
|
#endif /*IPSEC*/
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
{
|
|
int faith;
|
|
|
|
#if defined(NFAITH) && NFAITH > 0
|
|
faith = faithprefix(&ip6->ip6_dst);
|
|
#else
|
|
faith = 0;
|
|
#endif
|
|
in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src,
|
|
th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige);
|
|
if (!in6p && !vestige.valid) {
|
|
TCP_STATINC(TCP_STAT_PCBHASHMISS);
|
|
in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst,
|
|
th->th_dport, faith);
|
|
}
|
|
if (!in6p && !vestige.valid) {
|
|
TCP_STATINC(TCP_STAT_NOPORT);
|
|
if (tcp_log_refused &&
|
|
(tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) {
|
|
tcp6_log_refused(ip6, th);
|
|
}
|
|
tcp_fields_to_host(th);
|
|
goto dropwithreset_ratelim;
|
|
}
|
|
#if defined(IPSEC)
|
|
if (ipsec_used && in6p && ipsec_in_reject(m, in6p)) {
|
|
goto drop;
|
|
}
|
|
#endif
|
|
break;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
tcp_fields_to_host(th);
|
|
|
|
/*
|
|
* 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) {
|
|
/* Check the minimum TTL for socket. */
|
|
if (ip->ip_ttl < inp->inp_ip_minttl)
|
|
goto drop;
|
|
|
|
tp = intotcpcb(inp);
|
|
so = inp->inp_socket;
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p) {
|
|
tp = in6totcpcb(in6p);
|
|
so = in6p->in6p_socket;
|
|
}
|
|
#endif
|
|
else if (vestige.valid) {
|
|
/* We do not support the resurrection of vtw tcpcps. */
|
|
tcp_vtw_input(th, &vestige, m, tlen);
|
|
m = NULL;
|
|
goto drop;
|
|
}
|
|
|
|
if (tp == NULL)
|
|
goto dropwithreset_ratelim;
|
|
if (tp->t_state == TCPS_CLOSED)
|
|
goto drop;
|
|
|
|
KASSERT(so->so_lock == softnet_lock);
|
|
KASSERT(solocked(so));
|
|
|
|
/* 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 = NULL;
|
|
}
|
|
ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m);
|
|
}
|
|
#endif
|
|
|
|
if (so->so_options & SO_DEBUG) {
|
|
#ifdef TCP_DEBUG
|
|
ostate = tp->t_state;
|
|
#endif
|
|
|
|
tcp_saveti = NULL;
|
|
if (iphlen + sizeof(struct tcphdr) > MHLEN)
|
|
goto nosave;
|
|
|
|
if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) {
|
|
tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT);
|
|
if (tcp_saveti == NULL)
|
|
goto nosave;
|
|
} else {
|
|
MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER);
|
|
if (tcp_saveti == NULL)
|
|
goto nosave;
|
|
MCLAIM(m, &tcp_mowner);
|
|
tcp_saveti->m_len = iphlen;
|
|
m_copydata(m, 0, iphlen,
|
|
mtod(tcp_saveti, void *));
|
|
}
|
|
|
|
if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) {
|
|
m_freem(tcp_saveti);
|
|
tcp_saveti = NULL;
|
|
} else {
|
|
tcp_saveti->m_len += sizeof(struct tcphdr);
|
|
memcpy(mtod(tcp_saveti, char *) + iphlen, th,
|
|
sizeof(struct tcphdr));
|
|
}
|
|
nosave:;
|
|
}
|
|
|
|
if (so->so_options & SO_ACCEPTCONN) {
|
|
union syn_cache_sa src;
|
|
union syn_cache_sa dst;
|
|
|
|
KASSERT(tp->t_state == TCPS_LISTEN);
|
|
|
|
memset(&src, 0, sizeof(src));
|
|
memset(&dst, 0, 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
|
|
}
|
|
|
|
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, 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.
|
|
*/
|
|
|
|
#ifdef INET6
|
|
/*
|
|
* If deprecated address is forbidden, we do
|
|
* not accept SYN to deprecated interface
|
|
* address to prevent any new inbound
|
|
* connection from getting established.
|
|
* When we do not accept SYN, we send a TCP
|
|
* RST, with deprecated source address (instead
|
|
* of dropping it). We compromise it as it is
|
|
* much better for peer to send a RST, and
|
|
* RST will be the final packet for the
|
|
* exchange.
|
|
*
|
|
* If we do not forbid deprecated addresses, we
|
|
* accept the SYN packet. RFC2462 does not
|
|
* suggest dropping SYN in this case.
|
|
* If we decipher RFC2462 5.5.4, it says like
|
|
* this:
|
|
* 1. use of deprecated addr with existing
|
|
* communication is okay - "SHOULD continue
|
|
* to be used"
|
|
* 2. use of it with new communication:
|
|
* (2a) "SHOULD NOT be used if alternate
|
|
* address with sufficient scope is
|
|
* available"
|
|
* (2b) nothing mentioned otherwise.
|
|
* Here we fall into (2b) case as we have no
|
|
* choice in our source address selection - we
|
|
* must obey the peer.
|
|
*
|
|
* The wording in RFC2462 is confusing, and
|
|
* there are multiple description text for
|
|
* deprecated address handling - worse, they
|
|
* are not exactly the same. I believe 5.5.4
|
|
* is the best one, so we follow 5.5.4.
|
|
*/
|
|
if (af == AF_INET6 && !ip6_use_deprecated) {
|
|
struct in6_ifaddr *ia6;
|
|
int s;
|
|
struct ifnet *rcvif = m_get_rcvif(m, &s);
|
|
if (rcvif == NULL)
|
|
goto dropwithreset; /* XXX */
|
|
if ((ia6 = in6ifa_ifpwithaddr(rcvif,
|
|
&ip6->ip6_dst)) &&
|
|
(ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
|
|
tp = NULL;
|
|
m_put_rcvif(rcvif, &s);
|
|
goto dropwithreset;
|
|
}
|
|
m_put_rcvif(rcvif, &s);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* LISTEN socket received a SYN from itself? This
|
|
* can't possibly be valid; drop the packet.
|
|
*/
|
|
if (th->th_sport == th->th_dport) {
|
|
int eq = 0;
|
|
|
|
switch (af) {
|
|
case AF_INET:
|
|
eq = in_hosteq(ip->ip_src, ip->ip_dst);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
eq = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src,
|
|
&ip6->ip6_dst);
|
|
break;
|
|
#endif
|
|
}
|
|
if (eq) {
|
|
TCP_STATINC(TCP_STAT_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, off,
|
|
so, m, optp, optlen, &opti))
|
|
m = NULL;
|
|
}
|
|
|
|
goto drop;
|
|
}
|
|
|
|
after_listen:
|
|
/*
|
|
* From here on, we're dealing with !LISTEN.
|
|
*/
|
|
KASSERT(tp->t_state != TCPS_LISTEN);
|
|
|
|
/*
|
|
* Segment received on connection.
|
|
* Reset idle time and keep-alive timer.
|
|
*/
|
|
tp->t_rcvtime = tcp_now;
|
|
if (TCPS_HAVEESTABLISHED(tp->t_state))
|
|
TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle);
|
|
|
|
/*
|
|
* Process options.
|
|
*/
|
|
#ifdef TCP_SIGNATURE
|
|
if (optp || (tp->t_flags & TF_SIGNATURE))
|
|
#else
|
|
if (optp)
|
|
#endif
|
|
if (tcp_dooptions(tp, optp, optlen, th, m, off, &opti) < 0)
|
|
goto drop;
|
|
|
|
if (TCP_SACK_ENABLED(tp)) {
|
|
tcp_del_sackholes(tp, th);
|
|
}
|
|
|
|
if (TCP_ECN_ALLOWED(tp)) {
|
|
if (tiflags & TH_CWR) {
|
|
tp->t_flags &= ~TF_ECN_SND_ECE;
|
|
}
|
|
switch (iptos & IPTOS_ECN_MASK) {
|
|
case IPTOS_ECN_CE:
|
|
tp->t_flags |= TF_ECN_SND_ECE;
|
|
TCP_STATINC(TCP_STAT_ECN_CE);
|
|
break;
|
|
case IPTOS_ECN_ECT0:
|
|
TCP_STATINC(TCP_STAT_ECN_ECT);
|
|
break;
|
|
case IPTOS_ECN_ECT1:
|
|
/* XXX: ignore for now -- rpaulo */
|
|
break;
|
|
}
|
|
/*
|
|
* Congestion experienced.
|
|
* Ignore if we are already trying to recover.
|
|
*/
|
|
if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover))
|
|
tp->t_congctl->cong_exp(tp);
|
|
}
|
|
|
|
if (opti.ts_present && opti.ts_ecr) {
|
|
/*
|
|
* Calculate the RTT from the returned time stamp and the
|
|
* connection's time base. If the time stamp is later than
|
|
* the current time, or is extremely old, fall back to non-1323
|
|
* RTT calculation. Since ts_rtt is unsigned, we can test both
|
|
* at the same time.
|
|
*
|
|
* Note that ts_rtt is in units of slow ticks (500
|
|
* ms). Since most earthbound RTTs are < 500 ms,
|
|
* observed values will have large quantization noise.
|
|
* Our smoothed RTT is then the fraction of observed
|
|
* samples that are 1 tick instead of 0 (times 500
|
|
* ms).
|
|
*
|
|
* ts_rtt is increased by 1 to denote a valid sample,
|
|
* with 0 indicating an invalid measurement. This
|
|
* extra 1 must be removed when ts_rtt is used, or
|
|
* else an erroneous extra 500 ms will result.
|
|
*/
|
|
ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1;
|
|
if (ts_rtt > TCP_PAWS_IDLE)
|
|
ts_rtt = 0;
|
|
} else {
|
|
ts_rtt = 0;
|
|
}
|
|
|
|
/*
|
|
* Fast path: check for the two common cases of a uni-directional
|
|
* data transfer. If:
|
|
* o We are in the ESTABLISHED state, and
|
|
* o The packet has no control flags, and
|
|
* o The packet is in-sequence, and
|
|
* o The window didn't change, and
|
|
* o We are not retransmitting
|
|
* It's a candidate.
|
|
*
|
|
* If the length (tlen) is zero and the ack moved forward, we're
|
|
* the sender side of the transfer. Just free the data acked and
|
|
* 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_ECE|TH_CWR|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.
|
|
* NOTE that the test is modified according to the latest
|
|
* proposal of the tcplw@cray.com list (Braden 1993/04/26).
|
|
*
|
|
* note that we already know
|
|
* TSTMP_GEQ(opti.ts_val, tp->ts_recent)
|
|
*/
|
|
if (opti.ts_present && SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
|
|
tp->ts_recent_age = tcp_now;
|
|
tp->ts_recent = opti.ts_val;
|
|
}
|
|
|
|
if (tlen == 0) {
|
|
/* Ack prediction. */
|
|
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_partialacks < 0) {
|
|
/*
|
|
* this is a pure ack for outstanding data.
|
|
*/
|
|
if (ts_rtt)
|
|
tcp_xmit_timer(tp, ts_rtt - 1);
|
|
else if (tp->t_rtttime &&
|
|
SEQ_GT(th->th_ack, tp->t_rtseq))
|
|
tcp_xmit_timer(tp,
|
|
tcp_now - tp->t_rtttime);
|
|
acked = th->th_ack - tp->snd_una;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_PREDACK]++;
|
|
tcps[TCP_STAT_RCVACKPACK]++;
|
|
tcps[TCP_STAT_RCVACKBYTE] += acked;
|
|
TCP_STAT_PUTREF();
|
|
nd_hint(tp);
|
|
|
|
if (acked > (tp->t_lastoff - tp->t_inoff))
|
|
tp->t_lastm = NULL;
|
|
sbdrop(&so->so_snd, acked);
|
|
tp->t_lastoff -= acked;
|
|
|
|
icmp_check(tp, th, acked);
|
|
|
|
tp->snd_una = th->th_ack;
|
|
tp->snd_fack = tp->snd_una;
|
|
if (SEQ_LT(tp->snd_high, tp->snd_una))
|
|
tp->snd_high = tp->snd_una;
|
|
/*
|
|
* drag snd_wl2 along so only newer
|
|
* ACKs can update the window size.
|
|
* also avoids the state where snd_wl2
|
|
* is eventually larger than th_ack and thus
|
|
* blocking the window update mechanism and
|
|
* the connection gets stuck for a loooong
|
|
* time in the zero sized send window state.
|
|
*
|
|
* see PR/kern 55567
|
|
*/
|
|
tp->snd_wl2 = tp->snd_una;
|
|
|
|
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/selnotify/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) {
|
|
KERNEL_LOCK(1, NULL);
|
|
(void)tcp_output(tp);
|
|
KERNEL_UNLOCK_ONE(NULL);
|
|
}
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
}
|
|
} else if (th->th_ack == tp->snd_una &&
|
|
TAILQ_FIRST(&tp->segq) == NULL &&
|
|
tlen <= sbspace(&so->so_rcv)) {
|
|
int newsize = 0;
|
|
|
|
/*
|
|
* this is a pure, in-sequence data packet
|
|
* with nothing on the reassembly queue and
|
|
* we have enough buffer space to take it.
|
|
*/
|
|
tp->rcv_nxt += tlen;
|
|
|
|
/*
|
|
* Pull rcv_up up to prevent seq wrap relative to
|
|
* rcv_nxt.
|
|
*/
|
|
tp->rcv_up = tp->rcv_nxt;
|
|
|
|
/*
|
|
* Pull snd_wl1 up to prevent seq wrap relative to
|
|
* th_seq.
|
|
*/
|
|
tp->snd_wl1 = th->th_seq;
|
|
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_PREDDAT]++;
|
|
tcps[TCP_STAT_RCVPACK]++;
|
|
tcps[TCP_STAT_RCVBYTE] += tlen;
|
|
TCP_STAT_PUTREF();
|
|
nd_hint(tp);
|
|
/*
|
|
* Automatic sizing enables the performance of large buffers
|
|
* and most of the efficiency of small ones by only allocating
|
|
* space when it is needed.
|
|
*
|
|
* On the receive side the socket buffer memory is only rarely
|
|
* used to any significant extent. This allows us to be much
|
|
* more aggressive in scaling the receive socket buffer. For
|
|
* the case that the buffer space is actually used to a large
|
|
* extent and we run out of kernel memory we can simply drop
|
|
* the new segments; TCP on the sender will just retransmit it
|
|
* later. Setting the buffer size too big may only consume too
|
|
* much kernel memory if the application doesn't read() from
|
|
* the socket or packet loss or reordering makes use of the
|
|
* reassembly queue.
|
|
*
|
|
* The criteria to step up the receive buffer one notch are:
|
|
* 1. the number of bytes received during the time it takes
|
|
* one timestamp to be reflected back to us (the RTT);
|
|
* 2. received bytes per RTT is within seven eighth of the
|
|
* current socket buffer size;
|
|
* 3. receive buffer size has not hit maximal automatic size;
|
|
*
|
|
* This algorithm does one step per RTT at most and only if
|
|
* we receive a bulk stream w/o packet losses or reorderings.
|
|
* Shrinking the buffer during idle times is not necessary as
|
|
* it doesn't consume any memory when idle.
|
|
*
|
|
* TODO: Only step up if the application is actually serving
|
|
* the buffer to better manage the socket buffer resources.
|
|
*/
|
|
if (tcp_do_autorcvbuf &&
|
|
opti.ts_ecr &&
|
|
(so->so_rcv.sb_flags & SB_AUTOSIZE)) {
|
|
if (opti.ts_ecr > tp->rfbuf_ts &&
|
|
opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) {
|
|
if (tp->rfbuf_cnt >
|
|
(so->so_rcv.sb_hiwat / 8 * 7) &&
|
|
so->so_rcv.sb_hiwat <
|
|
tcp_autorcvbuf_max) {
|
|
newsize =
|
|
uimin(so->so_rcv.sb_hiwat +
|
|
tcp_autorcvbuf_inc,
|
|
tcp_autorcvbuf_max);
|
|
}
|
|
/* Start over with next RTT. */
|
|
tp->rfbuf_ts = 0;
|
|
tp->rfbuf_cnt = 0;
|
|
} else
|
|
tp->rfbuf_cnt += tlen; /* add up */
|
|
}
|
|
|
|
/*
|
|
* Drop TCP, IP headers and TCP options then add data
|
|
* to socket buffer.
|
|
*/
|
|
if (so->so_state & SS_CANTRCVMORE) {
|
|
m_freem(m);
|
|
} else {
|
|
/*
|
|
* Set new socket buffer size.
|
|
* Give up when limit is reached.
|
|
*/
|
|
if (newsize)
|
|
if (!sbreserve(&so->so_rcv,
|
|
newsize, so))
|
|
so->so_rcv.sb_flags &= ~SB_AUTOSIZE;
|
|
m_adj(m, off + thlen);
|
|
sbappendstream(&so->so_rcv, m);
|
|
}
|
|
sorwakeup(so);
|
|
tcp_setup_ack(tp, th);
|
|
if (tp->t_flags & TF_ACKNOW) {
|
|
KERNEL_LOCK(1, NULL);
|
|
(void)tcp_output(tp);
|
|
KERNEL_UNLOCK_ONE(NULL);
|
|
}
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Compute mbuf offset to TCP data segment.
|
|
*/
|
|
hdroptlen = off + thlen;
|
|
|
|
/*
|
|
* Calculate amount of space in receive window. 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));
|
|
}
|
|
|
|
/* Reset receive buffer auto scaling when not in bulk receive mode. */
|
|
tp->rfbuf_ts = 0;
|
|
tp->rfbuf_cnt = 0;
|
|
|
|
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 seg contains a ECE and ECN support is enabled, the stream
|
|
* is ECN capable.
|
|
* 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;
|
|
if (SEQ_LT(tp->snd_high, tp->snd_una))
|
|
tp->snd_high = tp->snd_una;
|
|
TCP_TIMER_DISARM(tp, TCPT_REXMT);
|
|
|
|
if ((tiflags & TH_ECE) && tcp_do_ecn) {
|
|
tp->t_flags |= TF_ECN_PERMIT;
|
|
TCP_STATINC(TCP_STAT_ECN_SHS);
|
|
}
|
|
}
|
|
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 {
|
|
int ss = tcp_init_win;
|
|
if (inp != NULL && in_localaddr(inp->inp_faddr))
|
|
ss = tcp_init_win_local;
|
|
#ifdef INET6
|
|
if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr))
|
|
ss = tcp_init_win_local;
|
|
#endif
|
|
tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss);
|
|
}
|
|
|
|
tcp_rmx_rtt(tp);
|
|
if (tiflags & TH_ACK) {
|
|
TCP_STATINC(TCP_STAT_CONNECTS);
|
|
/*
|
|
* move tcp_established before soisconnected
|
|
* because upcall handler can drive tcp_output
|
|
* functionality.
|
|
* XXX we might call soisconnected at the end of
|
|
* all processing
|
|
*/
|
|
tcp_established(tp);
|
|
soisconnected(so);
|
|
/* 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, NULL, tlen);
|
|
/*
|
|
* if we didn't have to retransmit the SYN,
|
|
* use its rtt as our initial srtt & rtt var.
|
|
*/
|
|
if (tp->t_rtttime)
|
|
tcp_xmit_timer(tp, tcp_now - tp->t_rtttime);
|
|
} 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;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVPACKAFTERWIN]++;
|
|
tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop;
|
|
TCP_STAT_PUTREF();
|
|
}
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* From here on, we're dealing with !LISTEN and !SYN_SENT.
|
|
*/
|
|
KASSERT(tp->t_state != TCPS_LISTEN &&
|
|
tp->t_state != TCPS_SYN_SENT);
|
|
|
|
/*
|
|
* RFC1323 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 (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 {
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVDUPPACK]++;
|
|
tcps[TCP_STAT_RCVDUPBYTE] += tlen;
|
|
tcps[TCP_STAT_PAWSDROP]++;
|
|
TCP_STAT_PUTREF();
|
|
tcp_new_dsack(tp, th->th_seq, tlen);
|
|
goto dropafterack;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check that at least some bytes of the segment are within the
|
|
* receive window. If segment begins before rcv_nxt, drop leading
|
|
* data (and SYN); if nothing left, just ack.
|
|
*/
|
|
todrop = tp->rcv_nxt - th->th_seq;
|
|
dupseg = false;
|
|
if (todrop > 0) {
|
|
if (tiflags & TH_SYN) {
|
|
tiflags &= ~TH_SYN;
|
|
th->th_seq++;
|
|
tcp_urp_drop(th, 1, &tiflags);
|
|
todrop--;
|
|
}
|
|
if (todrop > tlen ||
|
|
(todrop == tlen && (tiflags & TH_FIN) == 0)) {
|
|
/*
|
|
* Any valid FIN or RST must be to the left of the
|
|
* window. At this point the FIN or RST must be a
|
|
* duplicate or out of sequence; drop it.
|
|
*/
|
|
if (tiflags & TH_RST)
|
|
goto drop;
|
|
tiflags &= ~(TH_FIN|TH_RST);
|
|
|
|
/*
|
|
* Send an ACK to resynchronize and drop any data.
|
|
* But keep on processing for RST or ACK.
|
|
*/
|
|
tp->t_flags |= TF_ACKNOW;
|
|
todrop = tlen;
|
|
dupseg = true;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVDUPPACK]++;
|
|
tcps[TCP_STAT_RCVDUPBYTE] += todrop;
|
|
TCP_STAT_PUTREF();
|
|
} else if ((tiflags & TH_RST) && th->th_seq != tp->rcv_nxt) {
|
|
/*
|
|
* Test for reset before adjusting the sequence
|
|
* number for overlapping data.
|
|
*/
|
|
goto dropafterack_ratelim;
|
|
} else {
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVPARTDUPPACK]++;
|
|
tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop;
|
|
TCP_STAT_PUTREF();
|
|
}
|
|
tcp_new_dsack(tp, th->th_seq, todrop);
|
|
hdroptlen += todrop; /* drop from head afterwards (m_adj) */
|
|
th->th_seq += todrop;
|
|
tlen -= todrop;
|
|
tcp_urp_drop(th, todrop, &tiflags);
|
|
}
|
|
|
|
/*
|
|
* If new data is 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);
|
|
TCP_STATINC(TCP_STAT_RCVAFTERCLOSE);
|
|
goto dropwithreset;
|
|
}
|
|
|
|
/*
|
|
* If the segment ends after the 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) {
|
|
TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN);
|
|
if (todrop >= tlen) {
|
|
/*
|
|
* The segment actually starts after the window.
|
|
* th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen
|
|
* th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0
|
|
* th->th_seq >= tp->rcv_nxt + tp->rcv_wnd
|
|
*/
|
|
TCP_STATADD(TCP_STAT_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.
|
|
*
|
|
* NOTE: We need to put the header fields back into
|
|
* network order.
|
|
*/
|
|
if ((tiflags & TH_SYN) &&
|
|
tp->t_state == TCPS_TIME_WAIT &&
|
|
SEQ_GT(th->th_seq, tp->rcv_nxt)) {
|
|
tp = tcp_close(tp);
|
|
tcp_fields_to_net(th);
|
|
m_freem(tcp_saveti);
|
|
tcp_saveti = NULL;
|
|
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 (if not RST) ack.
|
|
*/
|
|
if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
|
|
KASSERT(todrop == tlen);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
TCP_STATINC(TCP_STAT_RCVWINPROBE);
|
|
} else {
|
|
goto dropafterack;
|
|
}
|
|
} else {
|
|
TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop);
|
|
}
|
|
m_adj(m, -todrop);
|
|
tlen -= todrop;
|
|
tiflags &= ~(TH_PUSH|TH_FIN);
|
|
}
|
|
|
|
/*
|
|
* If last ACK falls within this segment's sequence numbers,
|
|
* record the timestamp.
|
|
* NOTE:
|
|
* 1) That the test incorporates suggestions from the latest
|
|
* proposal of the tcplw@cray.com list (Braden 1993/04/26).
|
|
* 2) That updating only on newer timestamps interferes with
|
|
* our earlier PAWS tests, so this check should be solely
|
|
* predicated on the sequence space of this segment.
|
|
* 3) That we modify the segment boundary check to be
|
|
* Last.ACK.Sent <= SEG.SEQ + SEG.Len
|
|
* instead of RFC1323's
|
|
* Last.ACK.Sent < SEG.SEQ + SEG.Len,
|
|
* This modified check allows us to overcome RFC1323's
|
|
* limitations as described in Stevens TCP/IP Illustrated
|
|
* Vol. 2 p.869. In such cases, we can still calculate the
|
|
* RTT correctly when RCV.NXT == Last.ACK.Sent.
|
|
*/
|
|
if (opti.ts_present &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
|
|
SEQ_LEQ(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:
|
|
* 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) {
|
|
if (th->th_seq != tp->rcv_nxt)
|
|
goto dropafterack_ratelim;
|
|
|
|
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;
|
|
TCP_STATINC(TCP_STAT_DROPS);
|
|
tp = tcp_close(tp);
|
|
goto drop;
|
|
|
|
case TCPS_CLOSING:
|
|
case TCPS_LAST_ACK:
|
|
case TCPS_TIME_WAIT:
|
|
tp = tcp_close(tp);
|
|
goto drop;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Since we've covered the SYN-SENT and SYN-RECEIVED states above
|
|
* we must be in a synchronized state. RFC793 states (under Reset
|
|
* Generation) that any unacceptable segment (an out-of-order SYN
|
|
* qualifies) received in a synchronized state must elicit only an
|
|
* empty acknowledgment segment ... and the connection remains in
|
|
* the same state.
|
|
*/
|
|
if (tiflags & TH_SYN) {
|
|
if (tp->rcv_nxt == th->th_seq) {
|
|
tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1,
|
|
TH_ACK);
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
}
|
|
|
|
goto dropafterack_ratelim;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* From here on, we're doing 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;
|
|
TCP_STATINC(TCP_STAT_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, NULL, tlen);
|
|
tp->snd_wl1 = th->th_seq - 1;
|
|
/* FALLTHROUGH */
|
|
|
|
/*
|
|
* 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 && !dupseg && tiwin == tp->snd_wnd) {
|
|
TCP_STATINC(TCP_STAT_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
|
|
* threshold of them, assume a packet
|
|
* has been dropped and retransmit it.
|
|
* Kludge snd_nxt & the congestion
|
|
* window so we send only this one
|
|
* packet.
|
|
*/
|
|
if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 ||
|
|
th->th_ack != tp->snd_una)
|
|
tp->t_dupacks = 0;
|
|
else if (tp->t_partialacks < 0 &&
|
|
(++tp->t_dupacks == tcprexmtthresh ||
|
|
TCP_FACK_FASTRECOV(tp))) {
|
|
/*
|
|
* Do the fast retransmit, and adjust
|
|
* congestion control paramenters.
|
|
*/
|
|
if (tp->t_congctl->fast_retransmit(tp, th)) {
|
|
/* False fast retransmit */
|
|
break;
|
|
}
|
|
goto drop;
|
|
} else if (tp->t_dupacks > tcprexmtthresh) {
|
|
tp->snd_cwnd += tp->t_segsz;
|
|
KERNEL_LOCK(1, NULL);
|
|
(void)tcp_output(tp);
|
|
KERNEL_UNLOCK_ONE(NULL);
|
|
goto drop;
|
|
}
|
|
} else {
|
|
/*
|
|
* If the ack appears to be very old, only
|
|
* allow data that is in-sequence. This
|
|
* makes it somewhat more difficult to insert
|
|
* forged data by guessing sequence numbers.
|
|
* Sent an ack to try to update the send
|
|
* sequence number on the other side.
|
|
*/
|
|
if (tlen && th->th_seq != tp->rcv_nxt &&
|
|
SEQ_LT(th->th_ack,
|
|
tp->snd_una - tp->max_sndwnd))
|
|
goto dropafterack;
|
|
}
|
|
break;
|
|
}
|
|
/*
|
|
* If the congestion window was inflated to account
|
|
* for the other side's cached packets, retract it.
|
|
*/
|
|
tp->t_congctl->fast_retransmit_newack(tp, th);
|
|
|
|
if (SEQ_GT(th->th_ack, tp->snd_max)) {
|
|
TCP_STATINC(TCP_STAT_RCVACKTOOMUCH);
|
|
goto dropafterack;
|
|
}
|
|
acked = th->th_ack - tp->snd_una;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVACKPACK]++;
|
|
tcps[TCP_STAT_RCVACKBYTE] += acked;
|
|
TCP_STAT_PUTREF();
|
|
|
|
/*
|
|
* 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 (ts_rtt)
|
|
tcp_xmit_timer(tp, ts_rtt - 1);
|
|
else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq))
|
|
tcp_xmit_timer(tp, tcp_now - tp->t_rtttime);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/*
|
|
* New data has been acked, adjust the congestion window.
|
|
*/
|
|
tp->t_congctl->newack(tp, th);
|
|
|
|
nd_hint(tp);
|
|
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 {
|
|
if (acked > (tp->t_lastoff - tp->t_inoff))
|
|
tp->t_lastm = NULL;
|
|
sbdrop(&so->so_snd, acked);
|
|
tp->t_lastoff -= acked;
|
|
if (tp->snd_wnd > acked)
|
|
tp->snd_wnd -= acked;
|
|
else
|
|
tp->snd_wnd = 0;
|
|
ourfinisacked = 0;
|
|
}
|
|
sowwakeup(so);
|
|
|
|
icmp_check(tp, th, acked);
|
|
|
|
tp->snd_una = th->th_ack;
|
|
if (SEQ_GT(tp->snd_una, tp->snd_fack))
|
|
tp->snd_fack = tp->snd_una;
|
|
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
|
tp->snd_nxt = tp->snd_una;
|
|
if (SEQ_LT(tp->snd_high, tp->snd_una))
|
|
tp->snd_high = 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 (tp->t_maxidle > 0)
|
|
TCP_TIMER_ARM(tp, TCPT_2MSL,
|
|
tp->t_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 * tp->t_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 * tp->t_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)
|
|
TCP_STATINC(TCP_STAT_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 &&
|
|
(so->so_options & SO_OOBINLINE) == 0)
|
|
tcp_pulloutofband(so, th, m, hdroptlen);
|
|
} 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:
|
|
|
|
/*
|
|
* Process the segment text, merging it into the TCP sequencing queue,
|
|
* and arranging for acknowledgement 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,
|
|
* tcp_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) {
|
|
/*
|
|
* Handle the common case:
|
|
* o Segment is the next to be received, and
|
|
* o The queue is empty, and
|
|
* o The connection is established
|
|
* In this case, we avoid calling tcp_reass.
|
|
*
|
|
* tcp_setup_ack: set DELACK for segments received in order,
|
|
* but ack immediately when segments are out of order (so that
|
|
* fast retransmit can work).
|
|
*/
|
|
TCP_REASS_LOCK(tp);
|
|
if (th->th_seq == tp->rcv_nxt &&
|
|
TAILQ_FIRST(&tp->segq) == NULL &&
|
|
tp->t_state == TCPS_ESTABLISHED) {
|
|
tcp_setup_ack(tp, th);
|
|
tp->rcv_nxt += tlen;
|
|
tiflags = th->th_flags & TH_FIN;
|
|
tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_RCVPACK]++;
|
|
tcps[TCP_STAT_RCVBYTE] += tlen;
|
|
TCP_STAT_PUTREF();
|
|
nd_hint(tp);
|
|
if (so->so_state & SS_CANTRCVMORE) {
|
|
m_freem(m);
|
|
} else {
|
|
m_adj(m, hdroptlen);
|
|
sbappendstream(&(so)->so_rcv, m);
|
|
}
|
|
TCP_REASS_UNLOCK(tp);
|
|
sorwakeup(so);
|
|
} else {
|
|
m_adj(m, hdroptlen);
|
|
tiflags = tcp_reass(tp, th, m, tlen);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
}
|
|
|
|
/*
|
|
* 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 * tp->t_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 * tp->t_msl);
|
|
break;
|
|
}
|
|
}
|
|
#ifdef TCP_DEBUG
|
|
if (so->so_options & SO_DEBUG)
|
|
tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0);
|
|
#endif
|
|
|
|
/*
|
|
* Return any desired output.
|
|
*/
|
|
if (needoutput || (tp->t_flags & TF_ACKNOW)) {
|
|
KERNEL_LOCK(1, NULL);
|
|
(void)tcp_output(tp);
|
|
KERNEL_UNLOCK_ONE(NULL);
|
|
}
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
|
|
if (tp->t_state == TCPS_TIME_WAIT
|
|
&& (so->so_state & SS_NOFDREF)
|
|
&& (tp->t_inpcb || af != AF_INET)
|
|
&& (tp->t_in6pcb || af != AF_INET6)
|
|
&& ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0
|
|
&& TAILQ_EMPTY(&tp->segq)
|
|
&& vtw_add(af, tp)) {
|
|
;
|
|
}
|
|
return;
|
|
|
|
badsyn:
|
|
/*
|
|
* Received a bad SYN. Increment counters and dropwithreset.
|
|
*/
|
|
TCP_STATINC(TCP_STAT_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;
|
|
goto dropafterack2;
|
|
|
|
dropafterack_ratelim:
|
|
/*
|
|
* We may want to rate-limit ACKs against SYN/RST attack.
|
|
*/
|
|
if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count,
|
|
tcp_ackdrop_ppslim) == 0) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
|
|
dropafterack2:
|
|
m_freem(m);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
KERNEL_LOCK(1, NULL);
|
|
(void)tcp_output(tp);
|
|
KERNEL_UNLOCK_ONE(NULL);
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
return;
|
|
|
|
dropwithreset_ratelim:
|
|
/*
|
|
* We may want to rate-limit RSTs in certain situations,
|
|
* particularly if we are sending an RST in response to
|
|
* an attempt to connect to or otherwise communicate with
|
|
* a port for which we have no socket.
|
|
*/
|
|
if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count,
|
|
tcp_rst_ppslim) == 0) {
|
|
/* XXX stat */
|
|
goto drop;
|
|
}
|
|
|
|
dropwithreset:
|
|
/*
|
|
* Generate a RST, dropping incoming segment.
|
|
* Make ACK acceptable to originator of segment.
|
|
*/
|
|
if (tiflags & TH_RST)
|
|
goto drop;
|
|
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;
|
|
|
|
badcsum:
|
|
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;
|
|
#ifdef TCP_DEBUG
|
|
if (so && (so->so_options & SO_DEBUG) != 0)
|
|
tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0);
|
|
#endif
|
|
}
|
|
if (tcp_saveti)
|
|
m_freem(tcp_saveti);
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
int
|
|
tcp_signature_apply(void *fstate, void *data, u_int len)
|
|
{
|
|
|
|
MD5Update(fstate, (u_char *)data, len);
|
|
return (0);
|
|
}
|
|
|
|
struct secasvar *
|
|
tcp_signature_getsav(struct mbuf *m)
|
|
{
|
|
struct ip *ip;
|
|
struct ip6_hdr *ip6;
|
|
|
|
ip = mtod(m, struct ip *);
|
|
switch (ip->ip_v) {
|
|
case 4:
|
|
ip = mtod(m, struct ip *);
|
|
ip6 = NULL;
|
|
break;
|
|
case 6:
|
|
ip = NULL;
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
break;
|
|
default:
|
|
return (NULL);
|
|
}
|
|
|
|
#ifdef IPSEC
|
|
union sockaddr_union dst;
|
|
|
|
/* Extract the destination from the IP header in the mbuf. */
|
|
memset(&dst, 0, sizeof(union sockaddr_union));
|
|
if (ip != NULL) {
|
|
dst.sa.sa_len = sizeof(struct sockaddr_in);
|
|
dst.sa.sa_family = AF_INET;
|
|
dst.sin.sin_addr = ip->ip_dst;
|
|
} else {
|
|
dst.sa.sa_len = sizeof(struct sockaddr_in6);
|
|
dst.sa.sa_family = AF_INET6;
|
|
dst.sin6.sin6_addr = ip6->ip6_dst;
|
|
}
|
|
|
|
/*
|
|
* Look up an SADB entry which matches the address of the peer.
|
|
*/
|
|
return KEY_LOOKUP_SA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0);
|
|
#else
|
|
return NULL;
|
|
#endif
|
|
}
|
|
|
|
int
|
|
tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff,
|
|
struct secasvar *sav, char *sig)
|
|
{
|
|
MD5_CTX ctx;
|
|
struct ip *ip;
|
|
struct ipovly *ipovly;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6;
|
|
struct ip6_hdr_pseudo ip6pseudo;
|
|
#endif
|
|
struct ippseudo ippseudo;
|
|
struct tcphdr th0;
|
|
int l, tcphdrlen;
|
|
|
|
if (sav == NULL)
|
|
return (-1);
|
|
|
|
tcphdrlen = th->th_off * 4;
|
|
|
|
switch (mtod(m, struct ip *)->ip_v) {
|
|
case 4:
|
|
MD5Init(&ctx);
|
|
ip = mtod(m, struct ip *);
|
|
memset(&ippseudo, 0, sizeof(ippseudo));
|
|
ipovly = (struct ipovly *)ip;
|
|
ippseudo.ippseudo_src = ipovly->ih_src;
|
|
ippseudo.ippseudo_dst = ipovly->ih_dst;
|
|
ippseudo.ippseudo_pad = 0;
|
|
ippseudo.ippseudo_p = IPPROTO_TCP;
|
|
ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff);
|
|
MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo));
|
|
break;
|
|
#if INET6
|
|
case 6:
|
|
MD5Init(&ctx);
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
memset(&ip6pseudo, 0, sizeof(ip6pseudo));
|
|
ip6pseudo.ip6ph_src = ip6->ip6_src;
|
|
in6_clearscope(&ip6pseudo.ip6ph_src);
|
|
ip6pseudo.ip6ph_dst = ip6->ip6_dst;
|
|
in6_clearscope(&ip6pseudo.ip6ph_dst);
|
|
ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff);
|
|
ip6pseudo.ip6ph_nxt = IPPROTO_TCP;
|
|
MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo));
|
|
break;
|
|
#endif
|
|
default:
|
|
return (-1);
|
|
}
|
|
|
|
th0 = *th;
|
|
th0.th_sum = 0;
|
|
MD5Update(&ctx, (char *)&th0, sizeof(th0));
|
|
|
|
l = m->m_pkthdr.len - thoff - tcphdrlen;
|
|
if (l > 0)
|
|
m_apply(m, thoff + tcphdrlen,
|
|
m->m_pkthdr.len - thoff - tcphdrlen,
|
|
tcp_signature_apply, &ctx);
|
|
|
|
MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth));
|
|
MD5Final(sig, &ctx);
|
|
|
|
return (0);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Parse and process tcp options.
|
|
*
|
|
* Returns -1 if this segment should be dropped. (eg. wrong signature)
|
|
* Otherwise returns 0.
|
|
*/
|
|
static int
|
|
tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, struct tcphdr *th,
|
|
struct mbuf *m, int toff, struct tcp_opt_info *oi)
|
|
{
|
|
u_int16_t mss;
|
|
int opt, optlen = 0;
|
|
#ifdef TCP_SIGNATURE
|
|
void *sigp = NULL;
|
|
char sigbuf[TCP_SIGLEN];
|
|
struct secasvar *sav = NULL;
|
|
#endif
|
|
|
|
for (; cp && cnt > 0; cnt -= optlen, cp += optlen) {
|
|
opt = cp[0];
|
|
if (opt == TCPOPT_EOL)
|
|
break;
|
|
if (opt == TCPOPT_NOP)
|
|
optlen = 1;
|
|
else {
|
|
if (cnt < 2)
|
|
break;
|
|
optlen = cp[1];
|
|
if (optlen < 2 || optlen > cnt)
|
|
break;
|
|
}
|
|
switch (opt) {
|
|
|
|
default:
|
|
continue;
|
|
|
|
case TCPOPT_MAXSEG:
|
|
if (optlen != TCPOLEN_MAXSEG)
|
|
continue;
|
|
if (!(th->th_flags & TH_SYN))
|
|
continue;
|
|
if (TCPS_HAVERCVDSYN(tp->t_state))
|
|
continue;
|
|
memcpy(&mss, cp + 2, sizeof(mss));
|
|
oi->maxseg = ntohs(mss);
|
|
break;
|
|
|
|
case TCPOPT_WINDOW:
|
|
if (optlen != TCPOLEN_WINDOW)
|
|
continue;
|
|
if (!(th->th_flags & TH_SYN))
|
|
continue;
|
|
if (TCPS_HAVERCVDSYN(tp->t_state))
|
|
continue;
|
|
tp->t_flags |= TF_RCVD_SCALE;
|
|
tp->requested_s_scale = cp[2];
|
|
if (tp->requested_s_scale > TCP_MAX_WINSHIFT) {
|
|
char buf[INET6_ADDRSTRLEN];
|
|
struct ip *ip = mtod(m, struct ip *);
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
|
|
#endif
|
|
|
|
switch (ip->ip_v) {
|
|
case 4:
|
|
in_print(buf, sizeof(buf),
|
|
&ip->ip_src);
|
|
break;
|
|
#ifdef INET6
|
|
case 6:
|
|
in6_print(buf, sizeof(buf),
|
|
&ip6->ip6_src);
|
|
break;
|
|
#endif
|
|
default:
|
|
strlcpy(buf, "(unknown)", sizeof(buf));
|
|
break;
|
|
}
|
|
|
|
log(LOG_ERR, "TCP: invalid wscale %d from %s, "
|
|
"assuming %d\n",
|
|
tp->requested_s_scale, buf,
|
|
TCP_MAX_WINSHIFT);
|
|
tp->requested_s_scale = TCP_MAX_WINSHIFT;
|
|
}
|
|
break;
|
|
|
|
case TCPOPT_TIMESTAMP:
|
|
if (optlen != TCPOLEN_TIMESTAMP)
|
|
continue;
|
|
oi->ts_present = 1;
|
|
memcpy(&oi->ts_val, cp + 2, sizeof(oi->ts_val));
|
|
NTOHL(oi->ts_val);
|
|
memcpy(&oi->ts_ecr, cp + 6, sizeof(oi->ts_ecr));
|
|
NTOHL(oi->ts_ecr);
|
|
|
|
if (!(th->th_flags & TH_SYN))
|
|
continue;
|
|
if (TCPS_HAVERCVDSYN(tp->t_state))
|
|
continue;
|
|
/*
|
|
* A timestamp received in a SYN makes
|
|
* it ok to send timestamp requests and replies.
|
|
*/
|
|
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;
|
|
if (TCPS_HAVERCVDSYN(tp->t_state))
|
|
continue;
|
|
if (tcp_do_sack) {
|
|
tp->t_flags |= TF_SACK_PERMIT;
|
|
tp->t_flags |= TF_WILL_SACK;
|
|
}
|
|
break;
|
|
|
|
case TCPOPT_SACK:
|
|
tcp_sack_option(tp, th, cp, optlen);
|
|
break;
|
|
#ifdef TCP_SIGNATURE
|
|
case TCPOPT_SIGNATURE:
|
|
if (optlen != TCPOLEN_SIGNATURE)
|
|
continue;
|
|
if (sigp &&
|
|
!consttime_memequal(sigp, cp + 2, TCP_SIGLEN))
|
|
return (-1);
|
|
|
|
sigp = sigbuf;
|
|
memcpy(sigbuf, cp + 2, TCP_SIGLEN);
|
|
tp->t_flags |= TF_SIGNATURE;
|
|
break;
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#ifndef TCP_SIGNATURE
|
|
return 0;
|
|
#else
|
|
if (tp->t_flags & TF_SIGNATURE) {
|
|
sav = tcp_signature_getsav(m);
|
|
if (sav == NULL && tp->t_state == TCPS_LISTEN)
|
|
return (-1);
|
|
}
|
|
|
|
if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE))
|
|
goto out;
|
|
|
|
if (sigp) {
|
|
char sig[TCP_SIGLEN];
|
|
|
|
tcp_fields_to_net(th);
|
|
if (tcp_signature(m, th, toff, sav, sig) < 0) {
|
|
tcp_fields_to_host(th);
|
|
goto out;
|
|
}
|
|
tcp_fields_to_host(th);
|
|
|
|
if (!consttime_memequal(sig, sigp, TCP_SIGLEN)) {
|
|
TCP_STATINC(TCP_STAT_BADSIG);
|
|
goto out;
|
|
} else
|
|
TCP_STATINC(TCP_STAT_GOODSIG);
|
|
|
|
key_sa_recordxfer(sav, m);
|
|
KEY_SA_UNREF(&sav);
|
|
}
|
|
return 0;
|
|
out:
|
|
if (sav != NULL)
|
|
KEY_SA_UNREF(&sav);
|
|
return -1;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* 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(struct socket *so, struct tcphdr *th,
|
|
struct mbuf *m, int off)
|
|
{
|
|
int cnt = off + th->th_urp - 1;
|
|
|
|
while (cnt >= 0) {
|
|
if (m->m_len > cnt) {
|
|
char *cp = mtod(m, char *) + cnt;
|
|
struct tcpcb *tp = sototcpcb(so);
|
|
|
|
tp->t_iobc = *cp;
|
|
tp->t_oobflags |= TCPOOB_HAVEDATA;
|
|
memmove(cp, cp + 1, (unsigned)(m->m_len - cnt - 1));
|
|
m->m_len--;
|
|
return;
|
|
}
|
|
cnt -= m->m_len;
|
|
m = m->m_next;
|
|
if (m == NULL)
|
|
break;
|
|
}
|
|
panic("tcp_pulloutofband");
|
|
}
|
|
|
|
/*
|
|
* Collect new round-trip time estimate
|
|
* and update averages and current timeout.
|
|
*
|
|
* rtt is in units of slow ticks (typically 500 ms) -- essentially the
|
|
* difference of two timestamps.
|
|
*/
|
|
void
|
|
tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt)
|
|
{
|
|
int32_t delta;
|
|
|
|
TCP_STATINC(TCP_STAT_RTTUPDATED);
|
|
if (tp->t_srtt != 0) {
|
|
/*
|
|
* Compute the amount to add to srtt for smoothing,
|
|
* *alpha, or 2^(-TCP_RTT_SHIFT). Because
|
|
* srtt is stored in 1/32 slow ticks, we conceptually
|
|
* shift left 5 bits, subtract srtt to get the
|
|
* diference, and then shift right by TCP_RTT_SHIFT
|
|
* (3) to obtain 1/8 of the difference.
|
|
*/
|
|
delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT);
|
|
/*
|
|
* This can never happen, because delta's lowest
|
|
* possible value is 1/8 of t_srtt. But if it does,
|
|
* set srtt to some reasonable value, here chosen
|
|
* as 1/8 tick.
|
|
*/
|
|
if ((tp->t_srtt += delta) <= 0)
|
|
tp->t_srtt = 1 << 2;
|
|
/*
|
|
* RFC2988 requires that rttvar be updated first.
|
|
* This code is compliant because "delta" is the old
|
|
* srtt minus the new observation (scaled).
|
|
*
|
|
* RFC2988 says:
|
|
* rttvar = (1-beta) * rttvar + beta * |srtt-observed|
|
|
*
|
|
* delta is in units of 1/32 ticks, and has then been
|
|
* divided by 8. This is equivalent to being in 1/16s
|
|
* units and divided by 4. Subtract from it 1/4 of
|
|
* the existing rttvar to form the (signed) amount to
|
|
* adjust.
|
|
*/
|
|
if (delta < 0)
|
|
delta = -delta;
|
|
delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
|
|
/*
|
|
* As with srtt, this should never happen. There is
|
|
* no support in RFC2988 for this operation. But 1/4s
|
|
* as rttvar when faced with something arguably wrong
|
|
* is ok.
|
|
*/
|
|
if ((tp->t_rttvar += delta) <= 0)
|
|
tp->t_rttvar = 1 << 2;
|
|
|
|
/*
|
|
* If srtt exceeds .01 second, ensure we use the 'remote' MSL
|
|
* Problem is: it doesn't work. Disabled by defaulting
|
|
* tcp_rttlocal to 0; see corresponding code in
|
|
* tcp_subr that selects local vs remote in a different way.
|
|
*
|
|
* The static branch prediction hint here should be removed
|
|
* when the rtt estimator is fixed and the rtt_enable code
|
|
* is turned back on.
|
|
*/
|
|
if (__predict_false(tcp_rttlocal) && tcp_msl_enable
|
|
&& tp->t_srtt > tcp_msl_remote_threshold
|
|
&& tp->t_msl < tcp_msl_remote) {
|
|
tp->t_msl = MIN(tcp_msl_remote, TCP_MAXMSL);
|
|
}
|
|
} else {
|
|
/*
|
|
* This is the first measurement. Per RFC2988, 2.2,
|
|
* set rtt=R and srtt=R/2.
|
|
* For srtt, storage representation is 1/32 ticks,
|
|
* so shift left by 5.
|
|
* For rttvar, storage representation is 1/16 ticks,
|
|
* So shift left by 4, but then right by 1 to halve.
|
|
*/
|
|
tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2);
|
|
tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1);
|
|
}
|
|
tp->t_rtttime = 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).
|
|
*/
|
|
TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
|
|
uimax(tp->t_rttmin, rtt + 2), 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;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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(&((const struct sockaddr_in *)(src))->sin_addr, \
|
|
((const struct sockaddr_in *)(src))->sin_port, \
|
|
((const struct sockaddr_in *)(dst))->sin_port); \
|
|
} while (/*CONSTCOND*/ 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(&((const struct sockaddr_in *)(src))->sin_addr, \
|
|
((const struct sockaddr_in *)(src))->sin_port, \
|
|
((const struct sockaddr_in *)(dst))->sin_port); \
|
|
break; \
|
|
case AF_INET6: \
|
|
hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \
|
|
((const struct sockaddr_in6 *)(src))->sin6_port, \
|
|
((const struct sockaddr_in6 *)(dst))->sin6_port); \
|
|
break; \
|
|
default: \
|
|
hash = 0; \
|
|
} \
|
|
} while (/*CONSTCOND*/0)
|
|
#endif /* INET6 */
|
|
|
|
static struct pool syn_cache_pool;
|
|
|
|
/*
|
|
* We don't estimate RTT with SYNs, so each packet starts with the default
|
|
* RTT and each timer step has a fixed timeout value.
|
|
*/
|
|
static inline void
|
|
syn_cache_timer_arm(struct syn_cache *sc)
|
|
{
|
|
|
|
TCPT_RANGESET(sc->sc_rxtcur,
|
|
TCPTV_SRTTDFLT * tcp_backoff[sc->sc_rxtshift], TCPTV_MIN,
|
|
TCPTV_REXMTMAX);
|
|
callout_reset(&sc->sc_timer,
|
|
sc->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, sc);
|
|
}
|
|
|
|
#define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase)
|
|
|
|
static inline void
|
|
syn_cache_rm(struct syn_cache *sc)
|
|
{
|
|
TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket,
|
|
sc, sc_bucketq);
|
|
sc->sc_tp = NULL;
|
|
LIST_REMOVE(sc, sc_tpq);
|
|
tcp_syn_cache[sc->sc_bucketidx].sch_length--;
|
|
callout_stop(&sc->sc_timer);
|
|
syn_cache_count--;
|
|
}
|
|
|
|
static inline void
|
|
syn_cache_put(struct syn_cache *sc)
|
|
{
|
|
if (sc->sc_ipopts)
|
|
(void) m_free(sc->sc_ipopts);
|
|
rtcache_free(&sc->sc_route);
|
|
sc->sc_flags |= SCF_DEAD;
|
|
if (!callout_invoking(&sc->sc_timer))
|
|
callout_schedule(&(sc)->sc_timer, 1);
|
|
}
|
|
|
|
void
|
|
syn_cache_init(void)
|
|
{
|
|
int i;
|
|
|
|
pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0,
|
|
"synpl", NULL, IPL_SOFTNET);
|
|
|
|
/* Initialize the hash buckets. */
|
|
for (i = 0; i < tcp_syn_cache_size; i++)
|
|
TAILQ_INIT(&tcp_syn_cache[i].sch_bucket);
|
|
}
|
|
|
|
void
|
|
syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp)
|
|
{
|
|
struct syn_cache_head *scp;
|
|
struct syn_cache *sc2;
|
|
int s;
|
|
|
|
/*
|
|
* If there are no entries in the hash table, reinitialize
|
|
* the hash secrets.
|
|
*/
|
|
if (syn_cache_count == 0) {
|
|
syn_hash1 = cprng_fast32();
|
|
syn_hash2 = cprng_fast32();
|
|
}
|
|
|
|
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) {
|
|
TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW);
|
|
/*
|
|
* The bucket is full. Toss the oldest element in the
|
|
* bucket. This will be the first entry in the bucket.
|
|
*/
|
|
sc2 = TAILQ_FIRST(&scp->sch_bucket);
|
|
#ifdef DIAGNOSTIC
|
|
/*
|
|
* This should never happen; we should always find an
|
|
* entry in our bucket.
|
|
*/
|
|
if (sc2 == NULL)
|
|
panic("syn_cache_insert: bucketoverflow: impossible");
|
|
#endif
|
|
syn_cache_rm(sc2);
|
|
syn_cache_put(sc2); /* calls pool_put but see spl above */
|
|
} else if (syn_cache_count >= tcp_syn_cache_limit) {
|
|
struct syn_cache_head *scp2, *sce;
|
|
|
|
TCP_STATINC(TCP_STAT_SC_OVERFLOWED);
|
|
/*
|
|
* The cache is full. Toss the oldest entry in the
|
|
* first non-empty bucket we can find.
|
|
*
|
|
* XXX We would really like to toss the oldest
|
|
* entry in the cache, but we hope that this
|
|
* condition doesn't happen very often.
|
|
*/
|
|
scp2 = scp;
|
|
if (TAILQ_EMPTY(&scp2->sch_bucket)) {
|
|
sce = &tcp_syn_cache[tcp_syn_cache_size];
|
|
for (++scp2; scp2 != scp; scp2++) {
|
|
if (scp2 >= sce)
|
|
scp2 = &tcp_syn_cache[0];
|
|
if (! TAILQ_EMPTY(&scp2->sch_bucket))
|
|
break;
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
/*
|
|
* This should never happen; we should always find a
|
|
* non-empty bucket.
|
|
*/
|
|
if (scp2 == scp)
|
|
panic("syn_cache_insert: cacheoverflow: "
|
|
"impossible");
|
|
#endif
|
|
}
|
|
sc2 = TAILQ_FIRST(&scp2->sch_bucket);
|
|
syn_cache_rm(sc2);
|
|
syn_cache_put(sc2); /* calls pool_put but see spl above */
|
|
}
|
|
|
|
/*
|
|
* Initialize the entry's timer.
|
|
*/
|
|
sc->sc_rxttot = 0;
|
|
sc->sc_rxtshift = 0;
|
|
syn_cache_timer_arm(sc);
|
|
|
|
/* Link it from tcpcb entry */
|
|
LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq);
|
|
|
|
/* Put it into the bucket. */
|
|
TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq);
|
|
scp->sch_length++;
|
|
syn_cache_count++;
|
|
|
|
TCP_STATINC(TCP_STAT_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.
|
|
*/
|
|
static void
|
|
syn_cache_timer(void *arg)
|
|
{
|
|
struct syn_cache *sc = arg;
|
|
|
|
mutex_enter(softnet_lock);
|
|
KERNEL_LOCK(1, NULL);
|
|
|
|
callout_ack(&sc->sc_timer);
|
|
|
|
if (__predict_false(sc->sc_flags & SCF_DEAD)) {
|
|
TCP_STATINC(TCP_STAT_SC_DELAYED_FREE);
|
|
goto free;
|
|
}
|
|
|
|
if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) {
|
|
/* Drop it -- too many retransmissions. */
|
|
goto dropit;
|
|
}
|
|
|
|
/*
|
|
* 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 >= MIN(tcp_keepinit, TCP_TIMER_MAXTICKS))
|
|
goto dropit;
|
|
|
|
TCP_STATINC(TCP_STAT_SC_RETRANSMITTED);
|
|
(void)syn_cache_respond(sc);
|
|
|
|
/* Advance the timer back-off. */
|
|
sc->sc_rxtshift++;
|
|
syn_cache_timer_arm(sc);
|
|
|
|
goto out;
|
|
|
|
dropit:
|
|
TCP_STATINC(TCP_STAT_SC_TIMED_OUT);
|
|
syn_cache_rm(sc);
|
|
if (sc->sc_ipopts)
|
|
(void) m_free(sc->sc_ipopts);
|
|
rtcache_free(&sc->sc_route);
|
|
|
|
free:
|
|
callout_destroy(&sc->sc_timer);
|
|
pool_put(&syn_cache_pool, sc);
|
|
|
|
out:
|
|
KERNEL_UNLOCK_ONE(NULL);
|
|
mutex_exit(softnet_lock);
|
|
}
|
|
|
|
/*
|
|
* Remove syn cache created by the specified tcb entry,
|
|
* because this does not make sense to keep them
|
|
* (if there's no tcb entry, syn cache entry will never be used)
|
|
*/
|
|
void
|
|
syn_cache_cleanup(struct tcpcb *tp)
|
|
{
|
|
struct syn_cache *sc, *nsc;
|
|
int s;
|
|
|
|
s = splsoftnet();
|
|
|
|
for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) {
|
|
nsc = LIST_NEXT(sc, sc_tpq);
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if (sc->sc_tp != tp)
|
|
panic("invalid sc_tp in syn_cache_cleanup");
|
|
#endif
|
|
syn_cache_rm(sc);
|
|
syn_cache_put(sc); /* calls pool_put but see spl above */
|
|
}
|
|
/* just for safety */
|
|
LIST_INIT(&tp->t_sc);
|
|
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Find an entry in the syn cache.
|
|
*/
|
|
struct syn_cache *
|
|
syn_cache_lookup(const struct sockaddr *src, const 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 = TAILQ_FIRST(&scp->sch_bucket); sc != NULL;
|
|
sc = TAILQ_NEXT(sc, sc_bucketq)) {
|
|
if (sc->sc_hash != hash)
|
|
continue;
|
|
if (!memcmp(&sc->sc_src, src, src->sa_len) &&
|
|
!memcmp(&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 it's
|
|
* 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 numbers; 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(struct sockaddr *src, struct sockaddr *dst,
|
|
struct tcphdr *th, struct socket *so, struct mbuf *m)
|
|
{
|
|
struct syn_cache *sc;
|
|
struct syn_cache_head *scp;
|
|
struct inpcb *inp = NULL;
|
|
#ifdef INET6
|
|
struct in6pcb *in6p = NULL;
|
|
#endif
|
|
struct tcpcb *tp;
|
|
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)) {
|
|
m_freem(m);
|
|
(void)syn_cache_respond(sc);
|
|
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.
|
|
*/
|
|
oso = so;
|
|
so = sonewconn(so, true);
|
|
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);
|
|
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(m);
|
|
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 */
|
|
memset(&in6p->in6p_laddr, 0, 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;
|
|
if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY)
|
|
in6p->in6p_flags |= IN6P_IPV6_V6ONLY;
|
|
else
|
|
in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY;
|
|
in6_pcbstate(in6p, IN6P_BOUND);
|
|
}
|
|
#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;
|
|
in6_pcbstate(in6p, IN6P_BOUND);
|
|
}
|
|
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 = NULL;
|
|
}
|
|
ip6_savecontrol(in6p, &in6p->in6p_options,
|
|
mtod(m, struct ip6_hdr *), m);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Give the new socket our cached route reference.
|
|
*/
|
|
if (inp) {
|
|
rtcache_copy(&inp->inp_route, &sc->sc_route);
|
|
rtcache_free(&sc->sc_route);
|
|
}
|
|
#ifdef INET6
|
|
else {
|
|
rtcache_copy(&in6p->in6p_route, &sc->sc_route);
|
|
rtcache_free(&sc->sc_route);
|
|
}
|
|
#endif
|
|
|
|
if (inp) {
|
|
struct sockaddr_in sin;
|
|
memcpy(&sin, src, src->sa_len);
|
|
if (in_pcbconnect(inp, &sin, &lwp0)) {
|
|
goto resetandabort;
|
|
}
|
|
}
|
|
#ifdef INET6
|
|
else if (in6p) {
|
|
struct sockaddr_in6 sin6;
|
|
memcpy(&sin6, src, src->sa_len);
|
|
if (src->sa_family == AF_INET) {
|
|
/* IPv4 packet to AF_INET6 socket */
|
|
in6_sin_2_v4mapsin6((struct sockaddr_in *)src, &sin6);
|
|
}
|
|
if (in6_pcbconnect(in6p, &sin6, NULL)) {
|
|
goto resetandabort;
|
|
}
|
|
}
|
|
#endif
|
|
else {
|
|
goto resetandabort;
|
|
}
|
|
|
|
if (inp)
|
|
tp = intotcpcb(inp);
|
|
#ifdef INET6
|
|
else if (in6p)
|
|
tp = in6totcpcb(in6p);
|
|
#endif
|
|
else
|
|
tp = NULL;
|
|
|
|
tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY;
|
|
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_REQ_SCALE|TF_RCVD_SCALE;
|
|
}
|
|
if (sc->sc_flags & SCF_TIMESTAMP)
|
|
tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP;
|
|
tp->ts_timebase = sc->sc_timebase;
|
|
|
|
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, tp->t_keepinit);
|
|
TCP_STATINC(TCP_STAT_ACCEPTS);
|
|
|
|
if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack)
|
|
tp->t_flags |= TF_WILL_SACK;
|
|
|
|
if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn)
|
|
tp->t_flags |= TF_ECN_PERMIT;
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
if (sc->sc_flags & SCF_SIGNATURE)
|
|
tp->t_flags |= TF_SIGNATURE;
|
|
#endif
|
|
|
|
/* 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 {
|
|
int ss = tcp_init_win;
|
|
if (inp != NULL && in_localaddr(inp->inp_faddr))
|
|
ss = tcp_init_win_local;
|
|
#ifdef INET6
|
|
if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr))
|
|
ss = tcp_init_win_local;
|
|
#endif
|
|
tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss);
|
|
}
|
|
|
|
tcp_rmx_rtt(tp);
|
|
tp->snd_wl1 = sc->sc_irs;
|
|
tp->rcv_up = sc->sc_irs + 1;
|
|
|
|
/*
|
|
* This is what would have happened in tcp_output() 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;
|
|
tp->t_partialacks = -1;
|
|
tp->t_dupacks = 0;
|
|
|
|
TCP_STATINC(TCP_STAT_SC_COMPLETED);
|
|
s = splsoftnet();
|
|
syn_cache_put(sc);
|
|
splx(s);
|
|
return so;
|
|
|
|
resetandabort:
|
|
(void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST);
|
|
abort:
|
|
if (so != NULL) {
|
|
(void) soqremque(so, 1);
|
|
(void) soabort(so);
|
|
mutex_enter(softnet_lock);
|
|
}
|
|
s = splsoftnet();
|
|
syn_cache_put(sc);
|
|
splx(s);
|
|
TCP_STATINC(TCP_STAT_SC_ABORTED);
|
|
return ((struct socket *)(-1));
|
|
}
|
|
|
|
/*
|
|
* This function is called when we get a RST for a
|
|
* non-existent connection, so that we can see if the
|
|
* connection is in the syn cache. If it is, zap it.
|
|
*/
|
|
|
|
void
|
|
syn_cache_reset(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);
|
|
TCP_STATINC(TCP_STAT_SC_RESET);
|
|
syn_cache_put(sc); /* calls pool_put but see spl above */
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
syn_cache_unreach(const struct sockaddr *src, const 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 retransmitted 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);
|
|
TCP_STATINC(TCP_STAT_SC_UNREACH);
|
|
syn_cache_put(sc); /* calls pool_put but see spl above */
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* 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(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th,
|
|
unsigned int toff, 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;
|
|
int s;
|
|
|
|
tp = sototcpcb(so);
|
|
|
|
/*
|
|
* Initialize some local state.
|
|
*/
|
|
win = sbspace(&so->so_rcv);
|
|
if (win > TCP_MAXWIN)
|
|
win = TCP_MAXWIN;
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
if (optp || (tp->t_flags & TF_SIGNATURE))
|
|
#else
|
|
if (optp)
|
|
#endif
|
|
{
|
|
tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
|
|
#ifdef TCP_SIGNATURE
|
|
tb.t_flags |= (tp->t_flags & TF_SIGNATURE);
|
|
#endif
|
|
tb.t_state = TCPS_LISTEN;
|
|
if (tcp_dooptions(&tb, optp, optlen, th, m, toff, oi) < 0)
|
|
return 0;
|
|
} else
|
|
tb.t_flags = 0;
|
|
|
|
switch (src->sa_family) {
|
|
case AF_INET:
|
|
/* Remember the IP options, if any. */
|
|
ipopts = ip_srcroute(m);
|
|
break;
|
|
default:
|
|
ipopts = NULL;
|
|
}
|
|
|
|
/*
|
|
* 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) {
|
|
TCP_STATINC(TCP_STAT_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;
|
|
m_freem(m);
|
|
if (syn_cache_respond(sc) == 0) {
|
|
uint64_t *tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_SNDACKS]++;
|
|
tcps[TCP_STAT_SNDTOTAL]++;
|
|
TCP_STAT_PUTREF();
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
s = splsoftnet();
|
|
sc = pool_get(&syn_cache_pool, PR_NOWAIT);
|
|
splx(s);
|
|
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.
|
|
*/
|
|
memset(sc, 0, sizeof(struct syn_cache));
|
|
callout_init(&sc->sc_timer, CALLOUT_MPSAFE);
|
|
memcpy(&sc->sc_src, src, src->sa_len);
|
|
memcpy(&sc->sc_dst, dst, dst->sa_len);
|
|
sc->sc_flags = 0;
|
|
sc->sc_ipopts = ipopts;
|
|
sc->sc_irs = th->th_seq;
|
|
switch (src->sa_family) {
|
|
case AF_INET:
|
|
{
|
|
struct sockaddr_in *srcin = (void *)src;
|
|
struct sockaddr_in *dstin = (void *)dst;
|
|
|
|
sc->sc_iss = tcp_new_iss1(&dstin->sin_addr,
|
|
&srcin->sin_addr, dstin->sin_port,
|
|
srcin->sin_port, sizeof(dstin->sin_addr));
|
|
break;
|
|
}
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
{
|
|
struct sockaddr_in6 *srcin6 = (void *)src;
|
|
struct sockaddr_in6 *dstin6 = (void *)dst;
|
|
|
|
sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr,
|
|
&srcin6->sin6_addr, dstin6->sin6_port,
|
|
srcin6->sin6_port, sizeof(dstin6->sin6_addr));
|
|
break;
|
|
}
|
|
#endif
|
|
}
|
|
sc->sc_peermaxseg = oi->maxseg;
|
|
sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ?
|
|
m_get_rcvif_NOMPSAFE(m) : NULL, sc->sc_src.sa.sa_family);
|
|
sc->sc_win = win;
|
|
sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */
|
|
sc->sc_timestamp = tb.ts_recent;
|
|
if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) ==
|
|
(TF_REQ_TSTMP|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;
|
|
/*
|
|
* Pick the smallest possible scaling factor that
|
|
* will still allow us to scale up to sb_max.
|
|
*
|
|
* We do this because there are broken firewalls that
|
|
* will corrupt the window scale option, leading to
|
|
* the other endpoint believing that our advertised
|
|
* window is unscaled. At scale factors larger than
|
|
* 5 the unscaled window will drop below 1500 bytes,
|
|
* leading to serious problems when traversing these
|
|
* broken firewalls.
|
|
*
|
|
* With the default sbmax of 256K, a scale factor
|
|
* of 3 will be chosen by this algorithm. Those who
|
|
* choose a larger sbmax should watch out
|
|
* for the compatibility problems mentioned above.
|
|
*
|
|
* RFC1323: The Window field in a SYN (i.e., a <SYN>
|
|
* or <SYN,ACK>) segment itself is never scaled.
|
|
*/
|
|
while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT &&
|
|
(TCP_MAXWIN << sc->sc_request_r_scale) < sb_max)
|
|
sc->sc_request_r_scale++;
|
|
} else {
|
|
sc->sc_requested_s_scale = 15;
|
|
sc->sc_request_r_scale = 15;
|
|
}
|
|
if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack)
|
|
sc->sc_flags |= SCF_SACK_PERMIT;
|
|
|
|
/*
|
|
* ECN setup packet received.
|
|
*/
|
|
if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn)
|
|
sc->sc_flags |= SCF_ECN_PERMIT;
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
if (tb.t_flags & TF_SIGNATURE)
|
|
sc->sc_flags |= SCF_SIGNATURE;
|
|
#endif
|
|
sc->sc_tp = tp;
|
|
m_freem(m);
|
|
if (syn_cache_respond(sc) == 0) {
|
|
uint64_t *tcps = TCP_STAT_GETREF();
|
|
tcps[TCP_STAT_SNDACKS]++;
|
|
tcps[TCP_STAT_SNDTOTAL]++;
|
|
TCP_STAT_PUTREF();
|
|
syn_cache_insert(sc, tp);
|
|
} else {
|
|
s = splsoftnet();
|
|
/*
|
|
* syn_cache_put() will try to schedule the timer, so
|
|
* we need to initialize it
|
|
*/
|
|
syn_cache_timer_arm(sc);
|
|
syn_cache_put(sc);
|
|
splx(s);
|
|
TCP_STATINC(TCP_STAT_SC_DROPPED);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* syn_cache_respond: (re)send SYN+ACK.
|
|
*
|
|
* Returns 0 on success.
|
|
*/
|
|
|
|
int
|
|
syn_cache_respond(struct syn_cache *sc)
|
|
{
|
|
#ifdef INET6
|
|
struct rtentry *rt = NULL;
|
|
#endif
|
|
struct route *ro;
|
|
u_int8_t *optp;
|
|
int optlen, error;
|
|
u_int16_t tlen;
|
|
struct ip *ip = NULL;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6 = NULL;
|
|
#endif
|
|
struct tcpcb *tp;
|
|
struct tcphdr *th;
|
|
struct mbuf *m;
|
|
u_int hlen;
|
|
#ifdef TCP_SIGNATURE
|
|
struct secasvar *sav = NULL;
|
|
u_int8_t *sigp = NULL;
|
|
#endif
|
|
|
|
ro = &sc->sc_route;
|
|
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:
|
|
return EAFNOSUPPORT;
|
|
}
|
|
|
|
/* Worst case scenario, since we don't know the option size yet. */
|
|
tlen = hlen + sizeof(struct tcphdr) + MAX_TCPOPTLEN;
|
|
KASSERT(max_linkhdr + tlen <= MCLBYTES);
|
|
|
|
/*
|
|
* Create the IP+TCP header from scratch.
|
|
*/
|
|
MGETHDR(m, M_DONTWAIT, MT_DATA);
|
|
if (m && (max_linkhdr + tlen) > MHLEN) {
|
|
MCLGET(m, M_DONTWAIT);
|
|
if ((m->m_flags & M_EXT) == 0) {
|
|
m_freem(m);
|
|
m = NULL;
|
|
}
|
|
}
|
|
if (m == NULL)
|
|
return ENOBUFS;
|
|
MCLAIM(m, &tcp_tx_mowner);
|
|
|
|
tp = sc->sc_tp;
|
|
|
|
/* Fixup the mbuf. */
|
|
m->m_data += max_linkhdr;
|
|
m_reset_rcvif(m);
|
|
memset(mtod(m, void *), 0, tlen);
|
|
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
ip = mtod(m, struct ip *);
|
|
ip->ip_v = 4;
|
|
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_vfc = IPV6_VERSION;
|
|
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:
|
|
panic("%s: impossible (1)", __func__);
|
|
}
|
|
|
|
th->th_seq = htonl(sc->sc_iss);
|
|
th->th_ack = htonl(sc->sc_irs + 1);
|
|
th->th_flags = TH_SYN|TH_ACK;
|
|
th->th_win = htons(sc->sc_win);
|
|
/* th_x2, th_sum, th_urp already 0 from memset */
|
|
|
|
/* Tack on the TCP options. */
|
|
optp = (u_int8_t *)(th + 1);
|
|
optlen = 0;
|
|
*optp++ = TCPOPT_MAXSEG;
|
|
*optp++ = TCPOLEN_MAXSEG;
|
|
*optp++ = (sc->sc_ourmaxseg >> 8) & 0xff;
|
|
*optp++ = sc->sc_ourmaxseg & 0xff;
|
|
optlen += TCPOLEN_MAXSEG;
|
|
|
|
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 += TCPOLEN_WINDOW + TCPOLEN_NOP;
|
|
optlen += TCPOLEN_WINDOW + TCPOLEN_NOP;
|
|
}
|
|
|
|
if (sc->sc_flags & SCF_SACK_PERMIT) {
|
|
/* Let the peer know that we will SACK. */
|
|
*optp++ = TCPOPT_SACK_PERMITTED;
|
|
*optp++ = TCPOLEN_SACK_PERMITTED;
|
|
optlen += TCPOLEN_SACK_PERMITTED;
|
|
}
|
|
|
|
if (sc->sc_flags & SCF_TIMESTAMP) {
|
|
while (optlen % 4 != 2) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
*optp++ = TCPOPT_TIMESTAMP;
|
|
*optp++ = TCPOLEN_TIMESTAMP;
|
|
u_int32_t *lp = (u_int32_t *)(optp);
|
|
/* Form timestamp option as shown in appendix A of RFC 1323. */
|
|
*lp++ = htonl(SYN_CACHE_TIMESTAMP(sc));
|
|
*lp = htonl(sc->sc_timestamp);
|
|
optp += TCPOLEN_TIMESTAMP - 2;
|
|
optlen += TCPOLEN_TIMESTAMP;
|
|
}
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
if (sc->sc_flags & SCF_SIGNATURE) {
|
|
sav = tcp_signature_getsav(m);
|
|
if (sav == NULL) {
|
|
m_freem(m);
|
|
return EPERM;
|
|
}
|
|
|
|
*optp++ = TCPOPT_SIGNATURE;
|
|
*optp++ = TCPOLEN_SIGNATURE;
|
|
sigp = optp;
|
|
memset(optp, 0, TCP_SIGLEN);
|
|
optp += TCP_SIGLEN;
|
|
optlen += TCPOLEN_SIGNATURE;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Terminate and pad TCP options to a 4 byte boundary.
|
|
*
|
|
* According to RFC793: "The content of the header beyond the
|
|
* End-of-Option option must be header padding (i.e., zero)."
|
|
* And later: "The padding is composed of zeros."
|
|
*/
|
|
if (optlen % 4) {
|
|
optlen += TCPOLEN_EOL;
|
|
*optp++ = TCPOPT_EOL;
|
|
}
|
|
while (optlen % 4) {
|
|
optlen += TCPOLEN_PAD;
|
|
*optp++ = TCPOPT_PAD;
|
|
}
|
|
|
|
/* Compute the actual values now that we've added the options. */
|
|
tlen = hlen + sizeof(struct tcphdr) + optlen;
|
|
m->m_len = m->m_pkthdr.len = tlen;
|
|
th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
if (sav) {
|
|
(void)tcp_signature(m, th, hlen, sav, sigp);
|
|
key_sa_recordxfer(sav, m);
|
|
KEY_SA_UNREF(&sav);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Send ECN SYN-ACK setup packet.
|
|
* Routes can be asymmetric, so, even if we receive a packet
|
|
* with ECE and CWR set, we must not assume no one will block
|
|
* the ECE packet we are about to send.
|
|
*/
|
|
if ((sc->sc_flags & SCF_ECN_PERMIT) && tp &&
|
|
SEQ_GEQ(tp->snd_nxt, tp->snd_max)) {
|
|
th->th_flags |= TH_ECE;
|
|
TCP_STATINC(TCP_STAT_ECN_SHS);
|
|
|
|
/*
|
|
* draft-ietf-tcpm-ecnsyn-00.txt
|
|
*
|
|
* "[...] a TCP node MAY respond to an ECN-setup
|
|
* SYN packet by setting ECT in the responding
|
|
* ECN-setup SYN/ACK packet, indicating to routers
|
|
* that the SYN/ACK packet is ECN-Capable.
|
|
* This allows a congested router along the path
|
|
* to mark the packet instead of dropping the
|
|
* packet as an indication of congestion."
|
|
*
|
|
* "[...] There can be a great benefit in setting
|
|
* an ECN-capable codepoint in SYN/ACK packets [...]
|
|
* Congestion is most likely to occur in
|
|
* the server-to-client direction. As a result,
|
|
* setting an ECN-capable codepoint in SYN/ACK
|
|
* packets can reduce the occurrence of three-second
|
|
* retransmit timeouts resulting from the drop
|
|
* of SYN/ACK packets."
|
|
*
|
|
* Page 4 and 6, January 2006.
|
|
*/
|
|
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
ip->ip_tos |= IPTOS_ECN_ECT0;
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20);
|
|
break;
|
|
#endif
|
|
}
|
|
TCP_STATINC(TCP_STAT_ECN_ECT);
|
|
}
|
|
|
|
|
|
/*
|
|
* Compute the packet's checksum.
|
|
*
|
|
* 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 = htons(tlen - hlen);
|
|
th->th_sum = 0;
|
|
th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
|
|
ip->ip_len = htons(tlen);
|
|
ip->ip_ttl = ip_defttl;
|
|
/* XXX tos? */
|
|
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);
|
|
ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
|
|
ip6->ip6_vfc |= IPV6_VERSION;
|
|
ip6->ip6_plen = htons(tlen - hlen);
|
|
/* ip6_hlim will be initialized afterwards */
|
|
/* XXX flowlabel? */
|
|
break;
|
|
#endif
|
|
}
|
|
|
|
/* XXX use IPsec policy on listening socket, on SYN ACK */
|
|
tp = sc->sc_tp;
|
|
|
|
switch (sc->sc_src.sa.sa_family) {
|
|
case AF_INET:
|
|
error = ip_output(m, sc->sc_ipopts, ro,
|
|
(ip_mtudisc ? IP_MTUDISC : 0),
|
|
NULL, tp ? tp->t_inpcb : NULL);
|
|
break;
|
|
#ifdef INET6
|
|
case AF_INET6:
|
|
ip6->ip6_hlim = in6_selecthlim(NULL,
|
|
(rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp : NULL);
|
|
rtcache_unref(rt, ro);
|
|
|
|
error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL,
|
|
tp ? tp->t_in6pcb : NULL, NULL);
|
|
break;
|
|
#endif
|
|
default:
|
|
panic("%s: impossible (2)", __func__);
|
|
}
|
|
|
|
return error;
|
|
}
|