b79ff9a30d
TCPSTAT_INC(), rather than directly manipulating the fields across the kernel. This will make it easier to change the implementation of these statistics, such as using per-CPU versions of the data structures. MFC after: 3 days
3462 lines
101 KiB
C
3462 lines
101 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ipfw.h" /* for ipfw_fwd */
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_ipsec.h"
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#include "opt_mac.h"
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#include "opt_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/proc.h> /* for proc0 declaration */
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#include <sys/protosw.h>
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#include <sys/signalvar.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <sys/syslog.h>
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#include <sys/systm.h>
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#include <sys/vimage.h>
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#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
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#include <vm/uma.h>
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#include <net/if.h>
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#include <net/route.h>
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#define TCPSTATES /* for logging */
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#include <netinet/in.h>
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#include <netinet/in_pcb.h>
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#include <netinet/in_systm.h>
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#include <netinet/in_var.h>
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#include <netinet/ip.h>
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#include <netinet/ip_icmp.h> /* required for icmp_var.h */
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#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */
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#include <netinet/ip_var.h>
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#include <netinet/ip_options.h>
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#include <netinet/ip6.h>
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#include <netinet/icmp6.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/nd6.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet6/tcp6_var.h>
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#include <netinet/tcpip.h>
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#include <netinet/tcp_syncache.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif /* TCPDEBUG */
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#include <netinet/vinet.h>
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#ifdef INET6
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#include <netinet6/vinet6.h>
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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/ipsec6.h>
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#endif /*IPSEC*/
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#include <machine/in_cksum.h>
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#include <security/mac/mac_framework.h>
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static const int tcprexmtthresh = 3;
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#ifdef VIMAGE_GLOBALS
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struct tcpstat tcpstat;
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int blackhole;
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int tcp_delack_enabled;
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int drop_synfin;
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int tcp_do_rfc3042;
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int tcp_do_rfc3390;
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int tcp_do_ecn;
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int tcp_ecn_maxretries;
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int tcp_insecure_rst;
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int tcp_do_autorcvbuf;
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int tcp_autorcvbuf_inc;
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int tcp_autorcvbuf_max;
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int tcp_do_rfc3465;
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int tcp_abc_l_var;
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#endif
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SYSCTL_V_STRUCT(V_NET, vnet_inet, _net_inet_tcp, TCPCTL_STATS, stats,
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CTLFLAG_RW, tcpstat , tcpstat,
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"TCP statistics (struct tcpstat, netinet/tcp_var.h)");
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int tcp_log_in_vain = 0;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW,
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&tcp_log_in_vain, 0, "Log all incoming TCP segments to closed ports");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
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blackhole, 0, "Do not send RST on segments to closed ports");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, delayed_ack,
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CTLFLAG_RW, tcp_delack_enabled, 0,
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"Delay ACK to try and piggyback it onto a data packet");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, drop_synfin,
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CTLFLAG_RW, drop_synfin, 0, "Drop TCP packets with SYN+FIN set");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_RW,
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tcp_do_rfc3042, 0, "Enable RFC 3042 (Limited Transmit)");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW,
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tcp_do_rfc3390, 0,
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"Enable RFC 3390 (Increasing TCP's Initial Congestion Window)");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW,
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tcp_do_rfc3465, 0,
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"Enable RFC 3465 (Appropriate Byte Counting)");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_RW,
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tcp_abc_l_var, 2,
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"Cap the max cwnd increment during slow-start to this number of segments");
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SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_ecn, OID_AUTO, enable,
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CTLFLAG_RW, tcp_do_ecn, 0, "TCP ECN support");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp_ecn, OID_AUTO, maxretries,
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CTLFLAG_RW, tcp_ecn_maxretries, 0, "Max retries before giving up on ECN");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, insecure_rst,
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CTLFLAG_RW, tcp_insecure_rst, 0,
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"Follow the old (insecure) criteria for accepting RST packets");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, recvbuf_auto,
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CTLFLAG_RW, tcp_do_autorcvbuf, 0,
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"Enable automatic receive buffer sizing");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, recvbuf_inc,
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CTLFLAG_RW, tcp_autorcvbuf_inc, 0,
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"Incrementor step size of automatic receive buffer");
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SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_tcp, OID_AUTO, recvbuf_max,
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CTLFLAG_RW, tcp_autorcvbuf_max, 0,
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"Max size of automatic receive buffer");
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int tcp_read_locking = 1;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, read_locking, CTLFLAG_RW,
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&tcp_read_locking, 0, "Enable read locking strategy");
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int tcp_rlock_atfirst;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, rlock_atfirst, CTLFLAG_RD,
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&tcp_rlock_atfirst, 0, "");
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int tcp_wlock_atfirst;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_wlock_atfirst, CTLFLAG_RD,
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&tcp_wlock_atfirst, 0, "");
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int tcp_wlock_upgraded;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, wlock_upgraded, CTLFLAG_RD,
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&tcp_wlock_upgraded, 0, "");
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int tcp_wlock_relocked;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, wlock_relocked, CTLFLAG_RD,
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&tcp_wlock_relocked, 0, "");
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int tcp_wlock_looped;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, wlock_looped, CTLFLAG_RD,
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&tcp_wlock_looped, 0, "");
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#ifdef VIMAGE_GLOBALS
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struct inpcbhead tcb;
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struct inpcbinfo tcbinfo;
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#endif
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#define tcb6 tcb /* for KAME src sync over BSD*'s */
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static void tcp_dooptions(struct tcpopt *, u_char *, int, int);
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static void tcp_do_segment(struct mbuf *, struct tcphdr *,
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struct socket *, struct tcpcb *, int, int, uint8_t,
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int);
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static void tcp_dropwithreset(struct mbuf *, struct tcphdr *,
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struct tcpcb *, int, int);
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static void tcp_pulloutofband(struct socket *,
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struct tcphdr *, struct mbuf *, int);
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static void tcp_xmit_timer(struct tcpcb *, int);
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static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *);
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static void inline
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tcp_congestion_exp(struct tcpcb *);
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static void inline
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tcp_congestion_exp(struct tcpcb *tp)
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{
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u_int win;
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win = min(tp->snd_wnd, tp->snd_cwnd) /
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2 / tp->t_maxseg;
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if (win < 2)
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win = 2;
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tp->snd_ssthresh = win * tp->t_maxseg;
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ENTER_FASTRECOVERY(tp);
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tp->snd_recover = tp->snd_max;
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if (tp->t_flags & TF_ECN_PERMIT)
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tp->t_flags |= TF_ECN_SND_CWR;
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}
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/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
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#ifdef INET6
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#define ND6_HINT(tp) \
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do { \
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if ((tp) && (tp)->t_inpcb && \
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((tp)->t_inpcb->inp_vflag & INP_IPV6) != 0) \
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nd6_nud_hint(NULL, NULL, 0); \
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} while (0)
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#else
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#define ND6_HINT(tp)
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#endif
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|
|
/*
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* Indicate whether this ack should be delayed. We can delay the ack if
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* - there is no delayed ack timer in progress and
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* - our last ack wasn't a 0-sized window. We never want to delay
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* the ack that opens up a 0-sized window and
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* - delayed acks are enabled or
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* - this is a half-synchronized T/TCP connection.
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*/
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#define DELAY_ACK(tp) \
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((!tcp_timer_active(tp, TT_DELACK) && \
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(tp->t_flags & TF_RXWIN0SENT) == 0) && \
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(V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN)))
|
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|
|
/*
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|
* TCP input handling is split into multiple parts:
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* tcp6_input is a thin wrapper around tcp_input for the extended
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* ip6_protox[] call format in ip6_input
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* tcp_input handles primary segment validation, inpcb lookup and
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* SYN processing on listen sockets
|
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* tcp_do_segment processes the ACK and text of the segment for
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* establishing, established and closing connections
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*/
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#ifdef INET6
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int
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tcp6_input(struct mbuf **mp, int *offp, int proto)
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{
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INIT_VNET_INET6(curvnet);
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struct mbuf *m = *mp;
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struct in6_ifaddr *ia6;
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IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE);
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|
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/*
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* draft-itojun-ipv6-tcp-to-anycast
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* better place to put this in?
|
|
*/
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ia6 = ip6_getdstifaddr(m);
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if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) {
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struct ip6_hdr *ip6;
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|
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ip6 = mtod(m, struct ip6_hdr *);
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icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
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(caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
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return IPPROTO_DONE;
|
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}
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|
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tcp_input(m, *offp);
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return IPPROTO_DONE;
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}
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#endif
|
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|
|
void
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tcp_input(struct mbuf *m, int off0)
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|
{
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INIT_VNET_INET(curvnet);
|
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#ifdef INET6
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INIT_VNET_INET6(curvnet);
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#endif
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#ifdef IPSEC
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|
INIT_VNET_IPSEC(curvnet);
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|
#endif
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|
struct tcphdr *th;
|
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struct ip *ip = NULL;
|
|
struct ipovly *ipov;
|
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struct inpcb *inp = NULL;
|
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struct tcpcb *tp = NULL;
|
|
struct socket *so = NULL;
|
|
u_char *optp = NULL;
|
|
int optlen = 0;
|
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int len, tlen, off;
|
|
int drop_hdrlen;
|
|
int thflags;
|
|
int rstreason = 0; /* For badport_bandlim accounting purposes */
|
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uint8_t iptos;
|
|
#ifdef IPFIREWALL_FORWARD
|
|
struct m_tag *fwd_tag;
|
|
#endif
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6 = NULL;
|
|
int isipv6;
|
|
#else
|
|
const void *ip6 = NULL;
|
|
const int isipv6 = 0;
|
|
#endif
|
|
struct tcpopt to; /* options in this segment */
|
|
char *s = NULL; /* address and port logging */
|
|
int ti_locked;
|
|
#define TI_UNLOCKED 1
|
|
#define TI_RLOCKED 2
|
|
#define TI_WLOCKED 3
|
|
|
|
#ifdef TCPDEBUG
|
|
/*
|
|
* The size of tcp_saveipgen must be the size of the max ip header,
|
|
* now IPv6.
|
|
*/
|
|
u_char tcp_saveipgen[IP6_HDR_LEN];
|
|
struct tcphdr tcp_savetcp;
|
|
short ostate = 0;
|
|
#endif
|
|
|
|
#ifdef INET6
|
|
isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0;
|
|
#endif
|
|
|
|
to.to_flags = 0;
|
|
TCPSTAT_INC(tcps_rcvtotal);
|
|
|
|
if (isipv6) {
|
|
#ifdef INET6
|
|
/* IP6_EXTHDR_CHECK() is already done at tcp6_input(). */
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0;
|
|
if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
|
|
TCPSTAT_INC(tcps_rcvbadsum);
|
|
goto drop;
|
|
}
|
|
th = (struct tcphdr *)((caddr_t)ip6 + off0);
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
#else
|
|
th = NULL; /* XXX: Avoid compiler warning. */
|
|
#endif
|
|
} else {
|
|
/*
|
|
* Get IP and TCP header together in first mbuf.
|
|
* Note: IP leaves IP header in first mbuf.
|
|
*/
|
|
if (off0 > sizeof (struct ip)) {
|
|
ip_stripoptions(m, (struct mbuf *)0);
|
|
off0 = sizeof(struct ip);
|
|
}
|
|
if (m->m_len < sizeof (struct tcpiphdr)) {
|
|
if ((m = m_pullup(m, sizeof (struct tcpiphdr)))
|
|
== NULL) {
|
|
TCPSTAT_INC(tcps_rcvshort);
|
|
return;
|
|
}
|
|
}
|
|
ip = mtod(m, struct ip *);
|
|
ipov = (struct ipovly *)ip;
|
|
th = (struct tcphdr *)((caddr_t)ip + off0);
|
|
tlen = ip->ip_len;
|
|
|
|
if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
|
|
if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
|
|
th->th_sum = m->m_pkthdr.csum_data;
|
|
else
|
|
th->th_sum = in_pseudo(ip->ip_src.s_addr,
|
|
ip->ip_dst.s_addr,
|
|
htonl(m->m_pkthdr.csum_data +
|
|
ip->ip_len +
|
|
IPPROTO_TCP));
|
|
th->th_sum ^= 0xffff;
|
|
#ifdef TCPDEBUG
|
|
ipov->ih_len = (u_short)tlen;
|
|
ipov->ih_len = htons(ipov->ih_len);
|
|
#endif
|
|
} else {
|
|
/*
|
|
* Checksum extended TCP header and data.
|
|
*/
|
|
len = sizeof (struct ip) + tlen;
|
|
bzero(ipov->ih_x1, sizeof(ipov->ih_x1));
|
|
ipov->ih_len = (u_short)tlen;
|
|
ipov->ih_len = htons(ipov->ih_len);
|
|
th->th_sum = in_cksum(m, len);
|
|
}
|
|
if (th->th_sum) {
|
|
TCPSTAT_INC(tcps_rcvbadsum);
|
|
goto drop;
|
|
}
|
|
/* Re-initialization for later version check */
|
|
ip->ip_v = IPVERSION;
|
|
}
|
|
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
|
|
else
|
|
#endif
|
|
iptos = ip->ip_tos;
|
|
|
|
/*
|
|
* Check that TCP offset makes sense,
|
|
* pull out TCP options and adjust length. XXX
|
|
*/
|
|
off = th->th_off << 2;
|
|
if (off < sizeof (struct tcphdr) || off > tlen) {
|
|
TCPSTAT_INC(tcps_rcvbadoff);
|
|
goto drop;
|
|
}
|
|
tlen -= off; /* tlen is used instead of ti->ti_len */
|
|
if (off > sizeof (struct tcphdr)) {
|
|
if (isipv6) {
|
|
#ifdef INET6
|
|
IP6_EXTHDR_CHECK(m, off0, off, );
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
th = (struct tcphdr *)((caddr_t)ip6 + off0);
|
|
#endif
|
|
} else {
|
|
if (m->m_len < sizeof(struct ip) + off) {
|
|
if ((m = m_pullup(m, sizeof (struct ip) + off))
|
|
== NULL) {
|
|
TCPSTAT_INC(tcps_rcvshort);
|
|
return;
|
|
}
|
|
ip = mtod(m, struct ip *);
|
|
ipov = (struct ipovly *)ip;
|
|
th = (struct tcphdr *)((caddr_t)ip + off0);
|
|
}
|
|
}
|
|
optlen = off - sizeof (struct tcphdr);
|
|
optp = (u_char *)(th + 1);
|
|
}
|
|
thflags = th->th_flags;
|
|
|
|
/*
|
|
* Convert TCP protocol specific fields to host format.
|
|
*/
|
|
th->th_seq = ntohl(th->th_seq);
|
|
th->th_ack = ntohl(th->th_ack);
|
|
th->th_win = ntohs(th->th_win);
|
|
th->th_urp = ntohs(th->th_urp);
|
|
|
|
/*
|
|
* Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options.
|
|
*/
|
|
drop_hdrlen = off0 + off;
|
|
|
|
/*
|
|
* Locate pcb for segment, which requires a lock on tcbinfo.
|
|
* Optimisticaly acquire a global read lock rather than a write lock
|
|
* unless header flags necessarily imply a state change. There are
|
|
* two cases where we might discover later we need a write lock
|
|
* despite the flags: ACKs moving a connection out of the syncache,
|
|
* and ACKs for a connection in TIMEWAIT.
|
|
*/
|
|
if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 ||
|
|
tcp_read_locking == 0) {
|
|
INP_INFO_WLOCK(&V_tcbinfo);
|
|
ti_locked = TI_WLOCKED;
|
|
tcp_wlock_atfirst++;
|
|
} else {
|
|
INP_INFO_RLOCK(&V_tcbinfo);
|
|
ti_locked = TI_RLOCKED;
|
|
tcp_rlock_atfirst++;
|
|
}
|
|
|
|
findpcb:
|
|
#ifdef INVARIANTS
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
else
|
|
panic("%s: findpcb ti_locked %d\n", __func__, ti_locked);
|
|
#endif
|
|
|
|
#ifdef IPFIREWALL_FORWARD
|
|
/*
|
|
* Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain.
|
|
*/
|
|
fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
|
|
|
|
if (fwd_tag != NULL && isipv6 == 0) { /* IPv6 support is not yet */
|
|
struct sockaddr_in *next_hop;
|
|
|
|
next_hop = (struct sockaddr_in *)(fwd_tag+1);
|
|
/*
|
|
* Transparently forwarded. Pretend to be the destination.
|
|
* already got one like this?
|
|
*/
|
|
inp = in_pcblookup_hash(&V_tcbinfo,
|
|
ip->ip_src, th->th_sport,
|
|
ip->ip_dst, th->th_dport,
|
|
0, m->m_pkthdr.rcvif);
|
|
if (!inp) {
|
|
/* It's new. Try to find the ambushing socket. */
|
|
inp = in_pcblookup_hash(&V_tcbinfo,
|
|
ip->ip_src, th->th_sport,
|
|
next_hop->sin_addr,
|
|
next_hop->sin_port ?
|
|
ntohs(next_hop->sin_port) :
|
|
th->th_dport,
|
|
INPLOOKUP_WILDCARD,
|
|
m->m_pkthdr.rcvif);
|
|
}
|
|
/* Remove the tag from the packet. We don't need it anymore. */
|
|
m_tag_delete(m, fwd_tag);
|
|
} else
|
|
#endif /* IPFIREWALL_FORWARD */
|
|
{
|
|
if (isipv6) {
|
|
#ifdef INET6
|
|
inp = in6_pcblookup_hash(&V_tcbinfo,
|
|
&ip6->ip6_src, th->th_sport,
|
|
&ip6->ip6_dst, th->th_dport,
|
|
INPLOOKUP_WILDCARD,
|
|
m->m_pkthdr.rcvif);
|
|
#endif
|
|
} else
|
|
inp = in_pcblookup_hash(&V_tcbinfo,
|
|
ip->ip_src, th->th_sport,
|
|
ip->ip_dst, th->th_dport,
|
|
INPLOOKUP_WILDCARD,
|
|
m->m_pkthdr.rcvif);
|
|
}
|
|
|
|
/*
|
|
* If the INPCB does not exist then all data in the incoming
|
|
* segment is discarded and an appropriate RST is sent back.
|
|
* XXX MRT Send RST using which routing table?
|
|
*/
|
|
if (inp == NULL) {
|
|
/*
|
|
* Log communication attempts to ports that are not
|
|
* in use.
|
|
*/
|
|
if ((tcp_log_in_vain == 1 && (thflags & TH_SYN)) ||
|
|
tcp_log_in_vain == 2) {
|
|
if ((s = tcp_log_addrs(NULL, th, (void *)ip, ip6)))
|
|
log(LOG_INFO, "%s; %s: Connection attempt "
|
|
"to closed port\n", s, __func__);
|
|
}
|
|
/*
|
|
* When blackholing do not respond with a RST but
|
|
* completely ignore the segment and drop it.
|
|
*/
|
|
if ((V_blackhole == 1 && (thflags & TH_SYN)) ||
|
|
V_blackhole == 2)
|
|
goto dropunlock;
|
|
|
|
rstreason = BANDLIM_RST_CLOSEDPORT;
|
|
goto dropwithreset;
|
|
}
|
|
INP_WLOCK(inp);
|
|
if (!(inp->inp_flags & INP_HW_FLOWID)
|
|
&& (m->m_flags & M_FLOWID)
|
|
&& ((inp->inp_socket == NULL)
|
|
|| !(inp->inp_socket->so_options & SO_ACCEPTCONN))) {
|
|
inp->inp_flags |= INP_HW_FLOWID;
|
|
inp->inp_flags &= ~INP_SW_FLOWID;
|
|
inp->inp_flowid = m->m_pkthdr.flowid;
|
|
}
|
|
#ifdef IPSEC
|
|
#ifdef INET6
|
|
if (isipv6 && ipsec6_in_reject(m, inp)) {
|
|
V_ipsec6stat.in_polvio++;
|
|
goto dropunlock;
|
|
} else
|
|
#endif /* INET6 */
|
|
if (ipsec4_in_reject(m, inp) != 0) {
|
|
V_ipsec4stat.in_polvio++;
|
|
goto dropunlock;
|
|
}
|
|
#endif /* IPSEC */
|
|
|
|
/*
|
|
* Check the minimum TTL for socket.
|
|
*/
|
|
if (inp->inp_ip_minttl != 0) {
|
|
#ifdef INET6
|
|
if (isipv6 && inp->inp_ip_minttl > ip6->ip6_hlim)
|
|
goto dropunlock;
|
|
else
|
|
#endif
|
|
if (inp->inp_ip_minttl > ip->ip_ttl)
|
|
goto dropunlock;
|
|
}
|
|
|
|
/*
|
|
* A previous connection in TIMEWAIT state is supposed to catch stray
|
|
* or duplicate segments arriving late. If this segment was a
|
|
* legitimate new connection attempt the old INPCB gets removed and
|
|
* we can try again to find a listening socket.
|
|
*
|
|
* At this point, due to earlier optimism, we may hold a read lock on
|
|
* the inpcbinfo, rather than a write lock. If so, we need to
|
|
* upgrade, or if that fails, acquire a reference on the inpcb, drop
|
|
* all locks, acquire a global write lock, and then re-acquire the
|
|
* inpcb lock. We may at that point discover that another thread has
|
|
* tried to free the inpcb, in which case we need to loop back and
|
|
* try to find a new inpcb to deliver to.
|
|
*/
|
|
if (inp->inp_flags & INP_TIMEWAIT) {
|
|
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
|
|
("%s: INP_TIMEWAIT ti_locked %d", __func__, ti_locked));
|
|
|
|
if (ti_locked == TI_RLOCKED) {
|
|
if (rw_try_upgrade(&V_tcbinfo.ipi_lock) == 0) {
|
|
in_pcbref(inp);
|
|
INP_WUNLOCK(inp);
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
INP_INFO_WLOCK(&V_tcbinfo);
|
|
ti_locked = TI_WLOCKED;
|
|
INP_WLOCK(inp);
|
|
if (in_pcbrele(inp)) {
|
|
tcp_wlock_looped++;
|
|
inp = NULL;
|
|
goto findpcb;
|
|
}
|
|
tcp_wlock_relocked++;
|
|
} else {
|
|
ti_locked = TI_WLOCKED;
|
|
tcp_wlock_upgraded++;
|
|
}
|
|
}
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
|
|
if (thflags & TH_SYN)
|
|
tcp_dooptions(&to, optp, optlen, TO_SYN);
|
|
/*
|
|
* NB: tcp_twcheck unlocks the INP and frees the mbuf.
|
|
*/
|
|
if (tcp_twcheck(inp, &to, th, m, tlen))
|
|
goto findpcb;
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
return;
|
|
}
|
|
/*
|
|
* The TCPCB may no longer exist if the connection is winding
|
|
* down or it is in the CLOSED state. Either way we drop the
|
|
* segment and send an appropriate response.
|
|
*/
|
|
tp = intotcpcb(inp);
|
|
if (tp == NULL || tp->t_state == TCPS_CLOSED) {
|
|
rstreason = BANDLIM_RST_CLOSEDPORT;
|
|
goto dropwithreset;
|
|
}
|
|
|
|
/*
|
|
* We've identified a valid inpcb, but it could be that we need an
|
|
* inpcbinfo write lock and have only a read lock. In this case,
|
|
* attempt to upgrade/relock using the same strategy as the TIMEWAIT
|
|
* case above.
|
|
*/
|
|
if (tp->t_state != TCPS_ESTABLISHED ||
|
|
(thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 ||
|
|
tcp_read_locking == 0) {
|
|
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
|
|
("%s: upgrade check ti_locked %d", __func__, ti_locked));
|
|
|
|
if (ti_locked == TI_RLOCKED) {
|
|
if (rw_try_upgrade(&V_tcbinfo.ipi_lock) == 0) {
|
|
in_pcbref(inp);
|
|
INP_WUNLOCK(inp);
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
INP_INFO_WLOCK(&V_tcbinfo);
|
|
ti_locked = TI_WLOCKED;
|
|
INP_WLOCK(inp);
|
|
if (in_pcbrele(inp)) {
|
|
tcp_wlock_looped++;
|
|
inp = NULL;
|
|
goto findpcb;
|
|
}
|
|
tcp_wlock_relocked++;
|
|
} else {
|
|
ti_locked = TI_WLOCKED;
|
|
tcp_wlock_upgraded++;
|
|
}
|
|
}
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
}
|
|
|
|
#ifdef MAC
|
|
INP_WLOCK_ASSERT(inp);
|
|
if (mac_inpcb_check_deliver(inp, m))
|
|
goto dropunlock;
|
|
#endif
|
|
so = inp->inp_socket;
|
|
KASSERT(so != NULL, ("%s: so == NULL", __func__));
|
|
#ifdef TCPDEBUG
|
|
if (so->so_options & SO_DEBUG) {
|
|
ostate = tp->t_state;
|
|
if (isipv6) {
|
|
#ifdef INET6
|
|
bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6));
|
|
#endif
|
|
} else
|
|
bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip));
|
|
tcp_savetcp = *th;
|
|
}
|
|
#endif
|
|
/*
|
|
* When the socket is accepting connections (the INPCB is in LISTEN
|
|
* state) we look into the SYN cache if this is a new connection
|
|
* attempt or the completion of a previous one.
|
|
*/
|
|
if (so->so_options & SO_ACCEPTCONN) {
|
|
struct in_conninfo inc;
|
|
|
|
KASSERT(tp->t_state == TCPS_LISTEN, ("%s: so accepting but "
|
|
"tp not listening", __func__));
|
|
|
|
bzero(&inc, sizeof(inc));
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
inc.inc_flags |= INC_ISIPV6;
|
|
inc.inc6_faddr = ip6->ip6_src;
|
|
inc.inc6_laddr = ip6->ip6_dst;
|
|
} else
|
|
#endif
|
|
{
|
|
inc.inc_faddr = ip->ip_src;
|
|
inc.inc_laddr = ip->ip_dst;
|
|
}
|
|
inc.inc_fport = th->th_sport;
|
|
inc.inc_lport = th->th_dport;
|
|
|
|
/*
|
|
* Check for an existing connection attempt in syncache if
|
|
* the flag is only ACK. A successful lookup creates a new
|
|
* socket appended to the listen queue in SYN_RECEIVED state.
|
|
*/
|
|
if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) {
|
|
/*
|
|
* Parse the TCP options here because
|
|
* syncookies need access to the reflected
|
|
* timestamp.
|
|
*/
|
|
tcp_dooptions(&to, optp, optlen, 0);
|
|
/*
|
|
* NB: syncache_expand() doesn't unlock
|
|
* inp and tcpinfo locks.
|
|
*/
|
|
if (!syncache_expand(&inc, &to, th, &so, m)) {
|
|
/*
|
|
* No syncache entry or ACK was not
|
|
* for our SYN/ACK. Send a RST.
|
|
* NB: syncache did its own logging
|
|
* of the failure cause.
|
|
*/
|
|
rstreason = BANDLIM_RST_OPENPORT;
|
|
goto dropwithreset;
|
|
}
|
|
if (so == NULL) {
|
|
/*
|
|
* We completed the 3-way handshake
|
|
* but could not allocate a socket
|
|
* either due to memory shortage,
|
|
* listen queue length limits or
|
|
* global socket limits. Send RST
|
|
* or wait and have the remote end
|
|
* retransmit the ACK for another
|
|
* try.
|
|
*/
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Socket allocation failed due to "
|
|
"limits or memory shortage, %s\n",
|
|
s, __func__,
|
|
V_tcp_sc_rst_sock_fail ?
|
|
"sending RST" : "try again");
|
|
if (V_tcp_sc_rst_sock_fail) {
|
|
rstreason = BANDLIM_UNLIMITED;
|
|
goto dropwithreset;
|
|
} else
|
|
goto dropunlock;
|
|
}
|
|
/*
|
|
* Socket is created in state SYN_RECEIVED.
|
|
* Unlock the listen socket, lock the newly
|
|
* created socket and update the tp variable.
|
|
*/
|
|
INP_WUNLOCK(inp); /* listen socket */
|
|
inp = sotoinpcb(so);
|
|
INP_WLOCK(inp); /* new connection */
|
|
tp = intotcpcb(inp);
|
|
KASSERT(tp->t_state == TCPS_SYN_RECEIVED,
|
|
("%s: ", __func__));
|
|
/*
|
|
* Process the segment and the data it
|
|
* contains. tcp_do_segment() consumes
|
|
* the mbuf chain and unlocks the inpcb.
|
|
*/
|
|
tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen,
|
|
iptos, ti_locked);
|
|
INP_INFO_UNLOCK_ASSERT(&V_tcbinfo);
|
|
return;
|
|
}
|
|
/*
|
|
* Segment flag validation for new connection attempts:
|
|
*
|
|
* Our (SYN|ACK) response was rejected.
|
|
* Check with syncache and remove entry to prevent
|
|
* retransmits.
|
|
*
|
|
* NB: syncache_chkrst does its own logging of failure
|
|
* causes.
|
|
*/
|
|
if (thflags & TH_RST) {
|
|
syncache_chkrst(&inc, th);
|
|
goto dropunlock;
|
|
}
|
|
/*
|
|
* We can't do anything without SYN.
|
|
*/
|
|
if ((thflags & TH_SYN) == 0) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"SYN is missing, segment ignored\n",
|
|
s, __func__);
|
|
TCPSTAT_INC(tcps_badsyn);
|
|
goto dropunlock;
|
|
}
|
|
/*
|
|
* (SYN|ACK) is bogus on a listen socket.
|
|
*/
|
|
if (thflags & TH_ACK) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"SYN|ACK invalid, segment rejected\n",
|
|
s, __func__);
|
|
syncache_badack(&inc); /* XXX: Not needed! */
|
|
TCPSTAT_INC(tcps_badsyn);
|
|
rstreason = BANDLIM_RST_OPENPORT;
|
|
goto dropwithreset;
|
|
}
|
|
/*
|
|
* If the drop_synfin option is enabled, drop all
|
|
* segments with both the SYN and FIN bits set.
|
|
* This prevents e.g. nmap from identifying the
|
|
* TCP/IP stack.
|
|
* XXX: Poor reasoning. nmap has other methods
|
|
* and is constantly refining its stack detection
|
|
* strategies.
|
|
* XXX: This is a violation of the TCP specification
|
|
* and was used by RFC1644.
|
|
*/
|
|
if ((thflags & TH_FIN) && V_drop_synfin) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"SYN|FIN segment ignored (based on "
|
|
"sysctl setting)\n", s, __func__);
|
|
TCPSTAT_INC(tcps_badsyn);
|
|
goto dropunlock;
|
|
}
|
|
/*
|
|
* Segment's flags are (SYN) or (SYN|FIN).
|
|
*
|
|
* TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored
|
|
* as they do not affect the state of the TCP FSM.
|
|
* The data pointed to by TH_URG and th_urp is ignored.
|
|
*/
|
|
KASSERT((thflags & (TH_RST|TH_ACK)) == 0,
|
|
("%s: Listen socket: TH_RST or TH_ACK set", __func__));
|
|
KASSERT(thflags & (TH_SYN),
|
|
("%s: Listen socket: TH_SYN not set", __func__));
|
|
#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 (isipv6 && !V_ip6_use_deprecated) {
|
|
struct in6_ifaddr *ia6;
|
|
|
|
if ((ia6 = ip6_getdstifaddr(m)) &&
|
|
(ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Connection attempt to deprecated "
|
|
"IPv6 address rejected\n",
|
|
s, __func__);
|
|
rstreason = BANDLIM_RST_OPENPORT;
|
|
goto dropwithreset;
|
|
}
|
|
}
|
|
#endif
|
|
/*
|
|
* Basic sanity checks on incoming SYN requests:
|
|
* Don't respond if the destination is a link layer
|
|
* broadcast according to RFC1122 4.2.3.10, p. 104.
|
|
* If it is from this socket it must be forged.
|
|
* Don't respond if the source or destination is a
|
|
* global or subnet broad- or multicast address.
|
|
* Note that it is quite possible to receive unicast
|
|
* link-layer packets with a broadcast IP address. Use
|
|
* in_broadcast() to find them.
|
|
*/
|
|
if (m->m_flags & (M_BCAST|M_MCAST)) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Connection attempt from broad- or multicast "
|
|
"link layer address ignored\n", s, __func__);
|
|
goto dropunlock;
|
|
}
|
|
if (isipv6) {
|
|
#ifdef INET6
|
|
if (th->th_dport == th->th_sport &&
|
|
IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Connection attempt to/from self "
|
|
"ignored\n", s, __func__);
|
|
goto dropunlock;
|
|
}
|
|
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
|
|
IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Connection attempt from/to multicast "
|
|
"address ignored\n", s, __func__);
|
|
goto dropunlock;
|
|
}
|
|
#endif
|
|
} else {
|
|
if (th->th_dport == th->th_sport &&
|
|
ip->ip_dst.s_addr == ip->ip_src.s_addr) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Connection attempt from/to self "
|
|
"ignored\n", s, __func__);
|
|
goto dropunlock;
|
|
}
|
|
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
|
|
IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
|
|
ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
|
|
in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) {
|
|
if ((s = tcp_log_addrs(&inc, th, NULL, NULL)))
|
|
log(LOG_DEBUG, "%s; %s: Listen socket: "
|
|
"Connection attempt from/to broad- "
|
|
"or multicast address ignored\n",
|
|
s, __func__);
|
|
goto dropunlock;
|
|
}
|
|
}
|
|
/*
|
|
* SYN appears to be valid. Create compressed TCP state
|
|
* for syncache.
|
|
*/
|
|
#ifdef TCPDEBUG
|
|
if (so->so_options & SO_DEBUG)
|
|
tcp_trace(TA_INPUT, ostate, tp,
|
|
(void *)tcp_saveipgen, &tcp_savetcp, 0);
|
|
#endif
|
|
tcp_dooptions(&to, optp, optlen, TO_SYN);
|
|
syncache_add(&inc, &to, th, inp, &so, m);
|
|
/*
|
|
* Entry added to syncache and mbuf consumed.
|
|
* Everything already unlocked by syncache_add().
|
|
*/
|
|
INP_INFO_UNLOCK_ASSERT(&V_tcbinfo);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Segment belongs to a connection in SYN_SENT, ESTABLISHED or later
|
|
* state. tcp_do_segment() always consumes the mbuf chain, unlocks
|
|
* the inpcb, and unlocks pcbinfo.
|
|
*/
|
|
tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos, ti_locked);
|
|
INP_INFO_UNLOCK_ASSERT(&V_tcbinfo);
|
|
return;
|
|
|
|
dropwithreset:
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: dropwithreset ti_locked %d", __func__, ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
if (inp != NULL) {
|
|
tcp_dropwithreset(m, th, tp, tlen, rstreason);
|
|
INP_WUNLOCK(inp);
|
|
} else
|
|
tcp_dropwithreset(m, th, NULL, tlen, rstreason);
|
|
m = NULL; /* mbuf chain got consumed. */
|
|
goto drop;
|
|
|
|
dropunlock:
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: dropunlock ti_locked %d", __func__, ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
if (inp != NULL)
|
|
INP_WUNLOCK(inp);
|
|
|
|
drop:
|
|
INP_INFO_UNLOCK_ASSERT(&V_tcbinfo);
|
|
if (s != NULL)
|
|
free(s, M_TCPLOG);
|
|
if (m != NULL)
|
|
m_freem(m);
|
|
}
|
|
|
|
static void
|
|
tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
|
|
struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos,
|
|
int ti_locked)
|
|
{
|
|
INIT_VNET_INET(tp->t_vnet);
|
|
int thflags, acked, ourfinisacked, needoutput = 0;
|
|
int rstreason, todrop, win;
|
|
u_long tiwin;
|
|
struct tcpopt to;
|
|
|
|
#ifdef TCPDEBUG
|
|
/*
|
|
* The size of tcp_saveipgen must be the size of the max ip header,
|
|
* now IPv6.
|
|
*/
|
|
u_char tcp_saveipgen[IP6_HDR_LEN];
|
|
struct tcphdr tcp_savetcp;
|
|
short ostate = 0;
|
|
#endif
|
|
thflags = th->th_flags;
|
|
|
|
/*
|
|
* If this is either a state-changing packet or current state isn't
|
|
* established, we require a write lock on tcbinfo. Otherwise, we
|
|
* allow either a read lock or a write lock, as we may have acquired
|
|
* a write lock due to a race.
|
|
*
|
|
* Require a global write lock for SYN/FIN/RST segments or
|
|
* non-established connections; otherwise accept either a read or
|
|
* write lock, as we may have conservatively acquired a write lock in
|
|
* certain cases in tcp_input() (is this still true?). Currently we
|
|
* will never enter with no lock, so we try to drop it quickly in the
|
|
* common pure ack/pure data cases.
|
|
*/
|
|
if ((thflags & (TH_SYN | TH_FIN | TH_RST)) != 0 ||
|
|
tp->t_state != TCPS_ESTABLISHED) {
|
|
KASSERT(ti_locked == TI_WLOCKED, ("%s ti_locked %d for "
|
|
"SYN/FIN/RST/!EST", __func__, ti_locked));
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
} else {
|
|
#ifdef INVARIANTS
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
else
|
|
panic("%s: ti_locked %d for EST", __func__,
|
|
ti_locked);
|
|
#endif
|
|
}
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN",
|
|
__func__));
|
|
KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT",
|
|
__func__));
|
|
|
|
/*
|
|
* Segment received on connection.
|
|
* Reset idle time and keep-alive timer.
|
|
* XXX: This should be done after segment
|
|
* validation to ignore broken/spoofed segs.
|
|
*/
|
|
tp->t_rcvtime = ticks;
|
|
if (TCPS_HAVEESTABLISHED(tp->t_state))
|
|
tcp_timer_activate(tp, TT_KEEP, tcp_keepidle);
|
|
|
|
/*
|
|
* Unscale the window into a 32-bit value.
|
|
* For the SYN_SENT state the scale is zero.
|
|
*/
|
|
tiwin = th->th_win << tp->snd_scale;
|
|
|
|
/*
|
|
* TCP ECN processing.
|
|
*/
|
|
if (tp->t_flags & TF_ECN_PERMIT) {
|
|
switch (iptos & IPTOS_ECN_MASK) {
|
|
case IPTOS_ECN_CE:
|
|
tp->t_flags |= TF_ECN_SND_ECE;
|
|
TCPSTAT_INC(tcps_ecn_ce);
|
|
break;
|
|
case IPTOS_ECN_ECT0:
|
|
TCPSTAT_INC(tcps_ecn_ect0);
|
|
break;
|
|
case IPTOS_ECN_ECT1:
|
|
TCPSTAT_INC(tcps_ecn_ect1);
|
|
break;
|
|
}
|
|
|
|
if (thflags & TH_CWR)
|
|
tp->t_flags &= ~TF_ECN_SND_ECE;
|
|
|
|
/*
|
|
* Congestion experienced.
|
|
* Ignore if we are already trying to recover.
|
|
*/
|
|
if ((thflags & TH_ECE) &&
|
|
SEQ_LEQ(th->th_ack, tp->snd_recover)) {
|
|
TCPSTAT_INC(tcps_ecn_rcwnd);
|
|
tcp_congestion_exp(tp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Parse options on any incoming segment.
|
|
*/
|
|
tcp_dooptions(&to, (u_char *)(th + 1),
|
|
(th->th_off << 2) - sizeof(struct tcphdr),
|
|
(thflags & TH_SYN) ? TO_SYN : 0);
|
|
|
|
/*
|
|
* If echoed timestamp is later than the current time,
|
|
* fall back to non RFC1323 RTT calculation. Normalize
|
|
* timestamp if syncookies were used when this connection
|
|
* was established.
|
|
*/
|
|
if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) {
|
|
to.to_tsecr -= tp->ts_offset;
|
|
if (TSTMP_GT(to.to_tsecr, ticks))
|
|
to.to_tsecr = 0;
|
|
}
|
|
|
|
/*
|
|
* Process options only when we get SYN/ACK back. The SYN case
|
|
* for incoming connections is handled in tcp_syncache.
|
|
* According to RFC1323 the window field in a SYN (i.e., a <SYN>
|
|
* or <SYN,ACK>) segment itself is never scaled.
|
|
* XXX this is traditional behavior, may need to be cleaned up.
|
|
*/
|
|
if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
|
|
if ((to.to_flags & TOF_SCALE) &&
|
|
(tp->t_flags & TF_REQ_SCALE)) {
|
|
tp->t_flags |= TF_RCVD_SCALE;
|
|
tp->snd_scale = to.to_wscale;
|
|
}
|
|
/*
|
|
* Initial send window. It will be updated with
|
|
* the next incoming segment to the scaled value.
|
|
*/
|
|
tp->snd_wnd = th->th_win;
|
|
if (to.to_flags & TOF_TS) {
|
|
tp->t_flags |= TF_RCVD_TSTMP;
|
|
tp->ts_recent = to.to_tsval;
|
|
tp->ts_recent_age = ticks;
|
|
}
|
|
if (to.to_flags & TOF_MSS)
|
|
tcp_mss(tp, to.to_mss);
|
|
if ((tp->t_flags & TF_SACK_PERMIT) &&
|
|
(to.to_flags & TOF_SACKPERM) == 0)
|
|
tp->t_flags &= ~TF_SACK_PERMIT;
|
|
}
|
|
|
|
/*
|
|
* Header prediction: check for the two common cases
|
|
* of a uni-directional data xfer. If the packet has
|
|
* no control flags, is in-sequence, the window didn't
|
|
* change and we're not retransmitting, it's a
|
|
* candidate. If the length is zero and the ack moved
|
|
* forward, we're the sender side of the xfer. Just
|
|
* free the data acked & wake any higher level process
|
|
* that was blocked waiting for space. If the length
|
|
* is non-zero and the ack didn't move, we're the
|
|
* receiver side. If we're getting packets in-order
|
|
* (the reassembly queue is empty), add the data to
|
|
* the socket buffer and note that we need a delayed ack.
|
|
* Make sure that the hidden state-flags are also off.
|
|
* Since we check for TCPS_ESTABLISHED first, it can only
|
|
* be TH_NEEDSYN.
|
|
*/
|
|
if (tp->t_state == TCPS_ESTABLISHED &&
|
|
th->th_seq == tp->rcv_nxt &&
|
|
(thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
|
|
tp->snd_nxt == tp->snd_max &&
|
|
tiwin && tiwin == tp->snd_wnd &&
|
|
((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) &&
|
|
LIST_EMPTY(&tp->t_segq) &&
|
|
((to.to_flags & TOF_TS) == 0 ||
|
|
TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) {
|
|
|
|
/*
|
|
* 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).
|
|
*/
|
|
if ((to.to_flags & TOF_TS) != 0 &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
|
|
tp->ts_recent_age = ticks;
|
|
tp->ts_recent = to.to_tsval;
|
|
}
|
|
|
|
if (tlen == 0) {
|
|
if (SEQ_GT(th->th_ack, tp->snd_una) &&
|
|
SEQ_LEQ(th->th_ack, tp->snd_max) &&
|
|
tp->snd_cwnd >= tp->snd_wnd &&
|
|
((!V_tcp_do_newreno &&
|
|
!(tp->t_flags & TF_SACK_PERMIT) &&
|
|
tp->t_dupacks < tcprexmtthresh) ||
|
|
((V_tcp_do_newreno ||
|
|
(tp->t_flags & TF_SACK_PERMIT)) &&
|
|
!IN_FASTRECOVERY(tp) &&
|
|
(to.to_flags & TOF_SACK) == 0 &&
|
|
TAILQ_EMPTY(&tp->snd_holes)))) {
|
|
/*
|
|
* This is a pure ack for outstanding data.
|
|
*/
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: ti_locked %d on pure ACK",
|
|
__func__, ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
TCPSTAT_INC(tcps_predack);
|
|
|
|
/*
|
|
* "bad retransmit" recovery.
|
|
*/
|
|
if (tp->t_rxtshift == 1 &&
|
|
ticks < tp->t_badrxtwin) {
|
|
TCPSTAT_INC(tcps_sndrexmitbad);
|
|
tp->snd_cwnd = tp->snd_cwnd_prev;
|
|
tp->snd_ssthresh =
|
|
tp->snd_ssthresh_prev;
|
|
tp->snd_recover = tp->snd_recover_prev;
|
|
if (tp->t_flags & TF_WASFRECOVERY)
|
|
ENTER_FASTRECOVERY(tp);
|
|
tp->snd_nxt = tp->snd_max;
|
|
tp->t_badrxtwin = 0;
|
|
}
|
|
|
|
/*
|
|
* Recalculate the transmit timer / rtt.
|
|
*
|
|
* Some boxes send broken timestamp replies
|
|
* during the SYN+ACK phase, ignore
|
|
* timestamps of 0 or we could calculate a
|
|
* huge RTT and blow up the retransmit timer.
|
|
*/
|
|
if ((to.to_flags & TOF_TS) != 0 &&
|
|
to.to_tsecr) {
|
|
if (!tp->t_rttlow ||
|
|
tp->t_rttlow > ticks - to.to_tsecr)
|
|
tp->t_rttlow = ticks - to.to_tsecr;
|
|
tcp_xmit_timer(tp,
|
|
ticks - to.to_tsecr + 1);
|
|
} else if (tp->t_rtttime &&
|
|
SEQ_GT(th->th_ack, tp->t_rtseq)) {
|
|
if (!tp->t_rttlow ||
|
|
tp->t_rttlow > ticks - tp->t_rtttime)
|
|
tp->t_rttlow = ticks - tp->t_rtttime;
|
|
tcp_xmit_timer(tp,
|
|
ticks - tp->t_rtttime);
|
|
}
|
|
tcp_xmit_bandwidth_limit(tp, th->th_ack);
|
|
acked = th->th_ack - tp->snd_una;
|
|
TCPSTAT_INC(tcps_rcvackpack);
|
|
TCPSTAT_ADD(tcps_rcvackbyte, acked);
|
|
sbdrop(&so->so_snd, acked);
|
|
if (SEQ_GT(tp->snd_una, tp->snd_recover) &&
|
|
SEQ_LEQ(th->th_ack, tp->snd_recover))
|
|
tp->snd_recover = th->th_ack - 1;
|
|
tp->snd_una = th->th_ack;
|
|
/*
|
|
* Pull snd_wl2 up to prevent seq wrap relative
|
|
* to th_ack.
|
|
*/
|
|
tp->snd_wl2 = th->th_ack;
|
|
tp->t_dupacks = 0;
|
|
m_freem(m);
|
|
ND6_HINT(tp); /* Some progress has been made. */
|
|
|
|
/*
|
|
* If all outstanding data are acked, stop
|
|
* retransmit timer, otherwise restart timer
|
|
* using current (possibly backed-off) value.
|
|
* If process is waiting for space,
|
|
* wakeup/selwakeup/signal. If data
|
|
* are ready to send, let tcp_output
|
|
* decide between more output or persist.
|
|
*/
|
|
#ifdef TCPDEBUG
|
|
if (so->so_options & SO_DEBUG)
|
|
tcp_trace(TA_INPUT, ostate, tp,
|
|
(void *)tcp_saveipgen,
|
|
&tcp_savetcp, 0);
|
|
#endif
|
|
if (tp->snd_una == tp->snd_max)
|
|
tcp_timer_activate(tp, TT_REXMT, 0);
|
|
else if (!tcp_timer_active(tp, TT_PERSIST))
|
|
tcp_timer_activate(tp, TT_REXMT,
|
|
tp->t_rxtcur);
|
|
sowwakeup(so);
|
|
if (so->so_snd.sb_cc)
|
|
(void) tcp_output(tp);
|
|
goto check_delack;
|
|
}
|
|
} else if (th->th_ack == tp->snd_una &&
|
|
tlen <= sbspace(&so->so_rcv)) {
|
|
int newsize = 0; /* automatic sockbuf scaling */
|
|
|
|
/*
|
|
* This is a pure, in-sequence data packet with
|
|
* nothing on the reassembly queue and we have enough
|
|
* buffer space to take it.
|
|
*/
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: ti_locked %d on pure data "
|
|
"segment", __func__, ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
/* Clean receiver SACK report if present */
|
|
if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks)
|
|
tcp_clean_sackreport(tp);
|
|
TCPSTAT_INC(tcps_preddat);
|
|
tp->rcv_nxt += tlen;
|
|
/*
|
|
* Pull snd_wl1 up to prevent seq wrap relative to
|
|
* th_seq.
|
|
*/
|
|
tp->snd_wl1 = th->th_seq;
|
|
/*
|
|
* Pull rcv_up up to prevent seq wrap relative to
|
|
* rcv_nxt.
|
|
*/
|
|
tp->rcv_up = tp->rcv_nxt;
|
|
TCPSTAT_INC(tcps_rcvpack);
|
|
TCPSTAT_ADD(tcps_rcvbyte, tlen);
|
|
ND6_HINT(tp); /* Some progress has been made */
|
|
#ifdef TCPDEBUG
|
|
if (so->so_options & SO_DEBUG)
|
|
tcp_trace(TA_INPUT, ostate, tp,
|
|
(void *)tcp_saveipgen, &tcp_savetcp, 0);
|
|
#endif
|
|
/*
|
|
* Automatic sizing of receive socket buffer. Often the send
|
|
* buffer size is not optimally adjusted to the actual network
|
|
* conditions at hand (delay bandwidth product). Setting the
|
|
* buffer size too small limits throughput on links with high
|
|
* bandwidth and high delay (eg. trans-continental/oceanic links).
|
|
*
|
|
* 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 (V_tcp_do_autorcvbuf &&
|
|
to.to_tsecr &&
|
|
(so->so_rcv.sb_flags & SB_AUTOSIZE)) {
|
|
if (to.to_tsecr > tp->rfbuf_ts &&
|
|
to.to_tsecr - tp->rfbuf_ts < hz) {
|
|
if (tp->rfbuf_cnt >
|
|
(so->so_rcv.sb_hiwat / 8 * 7) &&
|
|
so->so_rcv.sb_hiwat <
|
|
V_tcp_autorcvbuf_max) {
|
|
newsize =
|
|
min(so->so_rcv.sb_hiwat +
|
|
V_tcp_autorcvbuf_inc,
|
|
V_tcp_autorcvbuf_max);
|
|
}
|
|
/* Start over with next RTT. */
|
|
tp->rfbuf_ts = 0;
|
|
tp->rfbuf_cnt = 0;
|
|
} else
|
|
tp->rfbuf_cnt += tlen; /* add up */
|
|
}
|
|
|
|
/* Add data to socket buffer. */
|
|
SOCKBUF_LOCK(&so->so_rcv);
|
|
if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
|
|
m_freem(m);
|
|
} else {
|
|
/*
|
|
* Set new socket buffer size.
|
|
* Give up when limit is reached.
|
|
*/
|
|
if (newsize)
|
|
if (!sbreserve_locked(&so->so_rcv,
|
|
newsize, so, NULL))
|
|
so->so_rcv.sb_flags &= ~SB_AUTOSIZE;
|
|
m_adj(m, drop_hdrlen); /* delayed header drop */
|
|
sbappendstream_locked(&so->so_rcv, m);
|
|
}
|
|
/* NB: sorwakeup_locked() does an implicit unlock. */
|
|
sorwakeup_locked(so);
|
|
if (DELAY_ACK(tp)) {
|
|
tp->t_flags |= TF_DELACK;
|
|
} else {
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tcp_output(tp);
|
|
}
|
|
goto check_delack;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Calculate amount of space in receive window,
|
|
* and then do TCP input processing.
|
|
* Receive window is amount of space in rcv queue,
|
|
* but not less than advertised window.
|
|
*/
|
|
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_RECEIVED:
|
|
* if seg contains an ACK, but not for our SYN/ACK, send a RST.
|
|
*/
|
|
case TCPS_SYN_RECEIVED:
|
|
if ((thflags & TH_ACK) &&
|
|
(SEQ_LEQ(th->th_ack, tp->snd_una) ||
|
|
SEQ_GT(th->th_ack, tp->snd_max))) {
|
|
rstreason = BANDLIM_RST_OPENPORT;
|
|
goto dropwithreset;
|
|
}
|
|
break;
|
|
|
|
/*
|
|
* 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 an 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 ((thflags & TH_ACK) &&
|
|
(SEQ_LEQ(th->th_ack, tp->iss) ||
|
|
SEQ_GT(th->th_ack, tp->snd_max))) {
|
|
rstreason = BANDLIM_UNLIMITED;
|
|
goto dropwithreset;
|
|
}
|
|
if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST))
|
|
tp = tcp_drop(tp, ECONNREFUSED);
|
|
if (thflags & TH_RST)
|
|
goto drop;
|
|
if (!(thflags & TH_SYN))
|
|
goto drop;
|
|
|
|
tp->irs = th->th_seq;
|
|
tcp_rcvseqinit(tp);
|
|
if (thflags & TH_ACK) {
|
|
TCPSTAT_INC(tcps_connects);
|
|
soisconnected(so);
|
|
#ifdef MAC
|
|
SOCK_LOCK(so);
|
|
mac_socketpeer_set_from_mbuf(m, so);
|
|
SOCK_UNLOCK(so);
|
|
#endif
|
|
/* Do window scaling on this connection? */
|
|
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
|
|
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
|
|
tp->rcv_scale = tp->request_r_scale;
|
|
}
|
|
tp->rcv_adv += tp->rcv_wnd;
|
|
tp->snd_una++; /* SYN is acked */
|
|
/*
|
|
* If there's data, delay ACK; if there's also a FIN
|
|
* ACKNOW will be turned on later.
|
|
*/
|
|
if (DELAY_ACK(tp) && tlen != 0)
|
|
tcp_timer_activate(tp, TT_DELACK,
|
|
tcp_delacktime);
|
|
else
|
|
tp->t_flags |= TF_ACKNOW;
|
|
|
|
if ((thflags & TH_ECE) && V_tcp_do_ecn) {
|
|
tp->t_flags |= TF_ECN_PERMIT;
|
|
TCPSTAT_INC(tcps_ecn_shs);
|
|
}
|
|
|
|
/*
|
|
* Received <SYN,ACK> in SYN_SENT[*] state.
|
|
* Transitions:
|
|
* SYN_SENT --> ESTABLISHED
|
|
* SYN_SENT* --> FIN_WAIT_1
|
|
*/
|
|
tp->t_starttime = ticks;
|
|
if (tp->t_flags & TF_NEEDFIN) {
|
|
tp->t_state = TCPS_FIN_WAIT_1;
|
|
tp->t_flags &= ~TF_NEEDFIN;
|
|
thflags &= ~TH_SYN;
|
|
} else {
|
|
tp->t_state = TCPS_ESTABLISHED;
|
|
tcp_timer_activate(tp, TT_KEEP, tcp_keepidle);
|
|
}
|
|
} else {
|
|
/*
|
|
* Received initial SYN in SYN-SENT[*] state =>
|
|
* simultaneous open. If segment contains CC option
|
|
* and there is a cached CC, apply TAO test.
|
|
* If it succeeds, connection is * half-synchronized.
|
|
* Otherwise, do 3-way handshake:
|
|
* SYN-SENT -> SYN-RECEIVED
|
|
* SYN-SENT* -> SYN-RECEIVED*
|
|
* If there was no CC option, clear cached CC value.
|
|
*/
|
|
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
|
|
tcp_timer_activate(tp, TT_REXMT, 0);
|
|
tp->t_state = TCPS_SYN_RECEIVED;
|
|
}
|
|
|
|
KASSERT(ti_locked == TI_WLOCKED, ("%s: trimthenstep6: "
|
|
"ti_locked %d", __func__, ti_locked));
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
/*
|
|
* 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;
|
|
thflags &= ~TH_FIN;
|
|
TCPSTAT_INC(tcps_rcvpackafterwin);
|
|
TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop);
|
|
}
|
|
tp->snd_wl1 = th->th_seq - 1;
|
|
tp->rcv_up = th->th_seq;
|
|
/*
|
|
* Client side of transaction: already sent SYN and data.
|
|
* If the remote host used T/TCP to validate the SYN,
|
|
* our data will be ACK'd; if so, enter normal data segment
|
|
* processing in the middle of step 5, ack processing.
|
|
* Otherwise, goto step 6.
|
|
*/
|
|
if (thflags & TH_ACK)
|
|
goto process_ACK;
|
|
|
|
goto step6;
|
|
|
|
/*
|
|
* If the state is LAST_ACK or CLOSING or TIME_WAIT:
|
|
* do normal processing.
|
|
*
|
|
* NB: Leftover from RFC1644 T/TCP. Cases to be reused later.
|
|
*/
|
|
case TCPS_LAST_ACK:
|
|
case TCPS_CLOSING:
|
|
break; /* continue normal processing */
|
|
}
|
|
|
|
/*
|
|
* States other than LISTEN or SYN_SENT.
|
|
* First check the RST flag and sequence number since reset segments
|
|
* are exempt from the timestamp and connection count tests. This
|
|
* fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix
|
|
* below which allowed reset segments in half the sequence space
|
|
* to fall though and be processed (which gives forged reset
|
|
* segments with a random sequence number a 50 percent chance of
|
|
* killing a connection).
|
|
* Then check timestamp, if present.
|
|
* Then check the connection count, if present.
|
|
* Then check that at least some bytes of segment are within
|
|
* receive window. If segment begins before rcv_nxt,
|
|
* drop leading data (and SYN); if nothing left, just ack.
|
|
*
|
|
*
|
|
* If the RST bit is set, check the sequence number to see
|
|
* if this is a valid reset segment.
|
|
* RFC 793 page 37:
|
|
* In all states except SYN-SENT, all reset (RST) segments
|
|
* are validated by checking their SEQ-fields. A reset is
|
|
* valid if its sequence number is in the window.
|
|
* Note: this does not take into account delayed ACKs, so
|
|
* we should test against last_ack_sent instead of rcv_nxt.
|
|
* The sequence number in the reset segment is normally an
|
|
* echo of our outgoing acknowlegement numbers, but some hosts
|
|
* send a reset with the sequence number at the rightmost edge
|
|
* of our receive window, and we have to handle this case.
|
|
* Note 2: Paul Watson's paper "Slipping in the Window" has shown
|
|
* that brute force RST attacks are possible. To combat this,
|
|
* we use a much stricter check while in the ESTABLISHED state,
|
|
* only accepting RSTs where the sequence number is equal to
|
|
* last_ack_sent. In all other states (the states in which a
|
|
* RST is more likely), the more permissive check is used.
|
|
* If we have multiple segments in flight, the initial reset
|
|
* segment sequence numbers will be to the left of last_ack_sent,
|
|
* but they will eventually catch up.
|
|
* In any case, it never made sense to trim reset segments to
|
|
* fit the receive window since RFC 1122 says:
|
|
* 4.2.2.12 RST Segment: RFC-793 Section 3.4
|
|
*
|
|
* A TCP SHOULD allow a received RST segment to include data.
|
|
*
|
|
* DISCUSSION
|
|
* It has been suggested that a RST segment could contain
|
|
* ASCII text that encoded and explained the cause of the
|
|
* RST. No standard has yet been established for such
|
|
* data.
|
|
*
|
|
* If the reset segment passes the sequence number test examine
|
|
* the state:
|
|
* SYN_RECEIVED STATE:
|
|
* If passive open, return to LISTEN state.
|
|
* If active open, inform user that connection was refused.
|
|
* ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES:
|
|
* Inform user that connection was reset, and close tcb.
|
|
* CLOSING, LAST_ACK STATES:
|
|
* Close the tcb.
|
|
* TIME_WAIT STATE:
|
|
* Drop the segment - see Stevens, vol. 2, p. 964 and
|
|
* RFC 1337.
|
|
*/
|
|
if (thflags & TH_RST) {
|
|
if (SEQ_GEQ(th->th_seq, tp->last_ack_sent - 1) &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
|
|
switch (tp->t_state) {
|
|
|
|
case TCPS_SYN_RECEIVED:
|
|
so->so_error = ECONNREFUSED;
|
|
goto close;
|
|
|
|
case TCPS_ESTABLISHED:
|
|
if (V_tcp_insecure_rst == 0 &&
|
|
!(SEQ_GEQ(th->th_seq, tp->rcv_nxt - 1) &&
|
|
SEQ_LEQ(th->th_seq, tp->rcv_nxt + 1)) &&
|
|
!(SEQ_GEQ(th->th_seq, tp->last_ack_sent - 1) &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent + 1))) {
|
|
TCPSTAT_INC(tcps_badrst);
|
|
goto drop;
|
|
}
|
|
/* FALLTHROUGH */
|
|
case TCPS_FIN_WAIT_1:
|
|
case TCPS_FIN_WAIT_2:
|
|
case TCPS_CLOSE_WAIT:
|
|
so->so_error = ECONNRESET;
|
|
close:
|
|
KASSERT(ti_locked == TI_WLOCKED,
|
|
("tcp_do_segment: TH_RST 1 ti_locked %d",
|
|
ti_locked));
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
|
|
tp->t_state = TCPS_CLOSED;
|
|
TCPSTAT_INC(tcps_drops);
|
|
tp = tcp_close(tp);
|
|
break;
|
|
|
|
case TCPS_CLOSING:
|
|
case TCPS_LAST_ACK:
|
|
KASSERT(ti_locked == TI_WLOCKED,
|
|
("tcp_do_segment: TH_RST 2 ti_locked %d",
|
|
ti_locked));
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
|
|
tp = tcp_close(tp);
|
|
break;
|
|
}
|
|
}
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* RFC 1323 PAWS: If we have a timestamp reply on this segment
|
|
* and it's less than ts_recent, drop it.
|
|
*/
|
|
if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
|
|
TSTMP_LT(to.to_tsval, tp->ts_recent)) {
|
|
|
|
/* Check to see if ts_recent is over 24 days old. */
|
|
if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) {
|
|
/*
|
|
* Invalidate ts_recent. If this segment updates
|
|
* ts_recent, the age will be reset later and ts_recent
|
|
* will get a valid value. If it does not, setting
|
|
* ts_recent to zero will at least satisfy the
|
|
* requirement that zero be placed in the timestamp
|
|
* echo reply when ts_recent isn't valid. The
|
|
* age isn't reset until we get a valid ts_recent
|
|
* because we don't want out-of-order segments to be
|
|
* dropped when ts_recent is old.
|
|
*/
|
|
tp->ts_recent = 0;
|
|
} else {
|
|
TCPSTAT_INC(tcps_rcvduppack);
|
|
TCPSTAT_ADD(tcps_rcvdupbyte, tlen);
|
|
TCPSTAT_INC(tcps_pawsdrop);
|
|
if (tlen)
|
|
goto dropafterack;
|
|
goto drop;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* In the SYN-RECEIVED state, validate that the packet belongs to
|
|
* this connection before trimming the data to fit the receive
|
|
* window. Check the sequence number versus IRS since we know
|
|
* the sequence numbers haven't wrapped. This is a partial fix
|
|
* for the "LAND" DoS attack.
|
|
*/
|
|
if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
|
|
rstreason = BANDLIM_RST_OPENPORT;
|
|
goto dropwithreset;
|
|
}
|
|
|
|
todrop = tp->rcv_nxt - th->th_seq;
|
|
if (todrop > 0) {
|
|
if (thflags & TH_SYN) {
|
|
thflags &= ~TH_SYN;
|
|
th->th_seq++;
|
|
if (th->th_urp > 1)
|
|
th->th_urp--;
|
|
else
|
|
thflags &= ~TH_URG;
|
|
todrop--;
|
|
}
|
|
/*
|
|
* Following if statement from Stevens, vol. 2, p. 960.
|
|
*/
|
|
if (todrop > tlen
|
|
|| (todrop == tlen && (thflags & TH_FIN) == 0)) {
|
|
/*
|
|
* Any valid FIN must be to the left of the window.
|
|
* At this point the FIN must be a duplicate or out
|
|
* of sequence; drop it.
|
|
*/
|
|
thflags &= ~TH_FIN;
|
|
|
|
/*
|
|
* Send an ACK to resynchronize and drop any data.
|
|
* But keep on processing for RST or ACK.
|
|
*/
|
|
tp->t_flags |= TF_ACKNOW;
|
|
todrop = tlen;
|
|
TCPSTAT_INC(tcps_rcvduppack);
|
|
TCPSTAT_ADD(tcps_rcvdupbyte, todrop);
|
|
} else {
|
|
TCPSTAT_INC(tcps_rcvpartduppack);
|
|
TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop);
|
|
}
|
|
drop_hdrlen += todrop; /* drop from the top afterwards */
|
|
th->th_seq += todrop;
|
|
tlen -= todrop;
|
|
if (th->th_urp > todrop)
|
|
th->th_urp -= todrop;
|
|
else {
|
|
thflags &= ~TH_URG;
|
|
th->th_urp = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If new data are received on a connection after the
|
|
* user processes are gone, then RST the other end.
|
|
*/
|
|
if ((so->so_state & SS_NOFDREF) &&
|
|
tp->t_state > TCPS_CLOSE_WAIT && tlen) {
|
|
char *s;
|
|
|
|
KASSERT(ti_locked == TI_WLOCKED, ("%s: SS_NOFDEREF && "
|
|
"CLOSE_WAIT && tlen ti_locked %d", __func__, ti_locked));
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
|
|
if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) {
|
|
log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data after socket "
|
|
"was closed, sending RST and removing tcpcb\n",
|
|
s, __func__, tcpstates[tp->t_state], tlen);
|
|
free(s, M_TCPLOG);
|
|
}
|
|
tp = tcp_close(tp);
|
|
TCPSTAT_INC(tcps_rcvafterclose);
|
|
rstreason = BANDLIM_UNLIMITED;
|
|
goto dropwithreset;
|
|
}
|
|
|
|
/*
|
|
* If segment ends after window, drop trailing data
|
|
* (and PUSH and FIN); if nothing left, just ACK.
|
|
*/
|
|
todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd);
|
|
if (todrop > 0) {
|
|
TCPSTAT_INC(tcps_rcvpackafterwin);
|
|
if (todrop >= tlen) {
|
|
TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen);
|
|
/*
|
|
* If window is closed can only take segments at
|
|
* window edge, and have to drop data and PUSH from
|
|
* incoming segments. Continue processing, but
|
|
* remember to ack. Otherwise, drop segment
|
|
* and ack.
|
|
*/
|
|
if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
|
|
tp->t_flags |= TF_ACKNOW;
|
|
TCPSTAT_INC(tcps_rcvwinprobe);
|
|
} else
|
|
goto dropafterack;
|
|
} else
|
|
TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop);
|
|
m_adj(m, -todrop);
|
|
tlen -= todrop;
|
|
thflags &= ~(TH_PUSH|TH_FIN);
|
|
}
|
|
|
|
/*
|
|
* If last ACK falls within this segment's sequence numbers,
|
|
* record its 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 ((to.to_flags & TOF_TS) != 0 &&
|
|
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
|
|
SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
|
|
((thflags & (TH_SYN|TH_FIN)) != 0))) {
|
|
tp->ts_recent_age = ticks;
|
|
tp->ts_recent = to.to_tsval;
|
|
}
|
|
|
|
/*
|
|
* If a SYN is in the window, then this is an
|
|
* error and we send an RST and drop the connection.
|
|
*/
|
|
if (thflags & TH_SYN) {
|
|
KASSERT(ti_locked == TI_WLOCKED,
|
|
("tcp_do_segment: TH_SYN ti_locked %d", ti_locked));
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
|
|
tp = tcp_drop(tp, ECONNRESET);
|
|
rstreason = BANDLIM_UNLIMITED;
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN
|
|
* flag is on (half-synchronized state), then queue data for
|
|
* later processing; else drop segment and return.
|
|
*/
|
|
if ((thflags & TH_ACK) == 0) {
|
|
if (tp->t_state == TCPS_SYN_RECEIVED ||
|
|
(tp->t_flags & TF_NEEDSYN))
|
|
goto step6;
|
|
else if (tp->t_flags & TF_ACKNOW)
|
|
goto dropafterack;
|
|
else
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* Ack processing.
|
|
*/
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* In SYN_RECEIVED state, the ack ACKs our SYN, so enter
|
|
* ESTABLISHED state and continue processing.
|
|
* The ACK was checked above.
|
|
*/
|
|
case TCPS_SYN_RECEIVED:
|
|
|
|
TCPSTAT_INC(tcps_connects);
|
|
soisconnected(so);
|
|
/* Do window scaling? */
|
|
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
|
|
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
|
|
tp->rcv_scale = tp->request_r_scale;
|
|
tp->snd_wnd = tiwin;
|
|
}
|
|
/*
|
|
* Make transitions:
|
|
* SYN-RECEIVED -> ESTABLISHED
|
|
* SYN-RECEIVED* -> FIN-WAIT-1
|
|
*/
|
|
tp->t_starttime = ticks;
|
|
if (tp->t_flags & TF_NEEDFIN) {
|
|
tp->t_state = TCPS_FIN_WAIT_1;
|
|
tp->t_flags &= ~TF_NEEDFIN;
|
|
} else {
|
|
tp->t_state = TCPS_ESTABLISHED;
|
|
tcp_timer_activate(tp, TT_KEEP, tcp_keepidle);
|
|
}
|
|
/*
|
|
* If segment contains data or ACK, will call tcp_reass()
|
|
* later; if not, do so now to pass queued data to user.
|
|
*/
|
|
if (tlen == 0 && (thflags & TH_FIN) == 0)
|
|
(void) tcp_reass(tp, (struct tcphdr *)0, 0,
|
|
(struct mbuf *)0);
|
|
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:
|
|
if (SEQ_GT(th->th_ack, tp->snd_max)) {
|
|
TCPSTAT_INC(tcps_rcvacktoomuch);
|
|
goto dropafterack;
|
|
}
|
|
if ((tp->t_flags & TF_SACK_PERMIT) &&
|
|
((to.to_flags & TOF_SACK) ||
|
|
!TAILQ_EMPTY(&tp->snd_holes)))
|
|
tcp_sack_doack(tp, &to, th->th_ack);
|
|
if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
|
|
if (tlen == 0 && tiwin == tp->snd_wnd) {
|
|
TCPSTAT_INC(tcps_rcvdupack);
|
|
/*
|
|
* If we have outstanding data (other than
|
|
* a window probe), this is a completely
|
|
* duplicate ack (ie, window info didn't
|
|
* change), the ack is the biggest we've
|
|
* seen and we've seen exactly our rexmt
|
|
* threshhold of them, assume a packet
|
|
* has been dropped and retransmit it.
|
|
* Kludge snd_nxt & the congestion
|
|
* window so we send only this one
|
|
* packet.
|
|
*
|
|
* We know we're losing at the current
|
|
* window size so do congestion avoidance
|
|
* (set ssthresh to half the current window
|
|
* and pull our congestion window back to
|
|
* the new ssthresh).
|
|
*
|
|
* Dup acks mean that packets have left the
|
|
* network (they're now cached at the receiver)
|
|
* so bump cwnd by the amount in the receiver
|
|
* to keep a constant cwnd packets in the
|
|
* network.
|
|
*
|
|
* When using TCP ECN, notify the peer that
|
|
* we reduced the cwnd.
|
|
*/
|
|
if (!tcp_timer_active(tp, TT_REXMT) ||
|
|
th->th_ack != tp->snd_una)
|
|
tp->t_dupacks = 0;
|
|
else if (++tp->t_dupacks > tcprexmtthresh ||
|
|
((V_tcp_do_newreno ||
|
|
(tp->t_flags & TF_SACK_PERMIT)) &&
|
|
IN_FASTRECOVERY(tp))) {
|
|
if ((tp->t_flags & TF_SACK_PERMIT) &&
|
|
IN_FASTRECOVERY(tp)) {
|
|
int awnd;
|
|
|
|
/*
|
|
* Compute the amount of data in flight first.
|
|
* We can inject new data into the pipe iff
|
|
* we have less than 1/2 the original window's
|
|
* worth of data in flight.
|
|
*/
|
|
awnd = (tp->snd_nxt - tp->snd_fack) +
|
|
tp->sackhint.sack_bytes_rexmit;
|
|
if (awnd < tp->snd_ssthresh) {
|
|
tp->snd_cwnd += tp->t_maxseg;
|
|
if (tp->snd_cwnd > tp->snd_ssthresh)
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
}
|
|
} else
|
|
tp->snd_cwnd += tp->t_maxseg;
|
|
(void) tcp_output(tp);
|
|
goto drop;
|
|
} else if (tp->t_dupacks == tcprexmtthresh) {
|
|
tcp_seq onxt = tp->snd_nxt;
|
|
|
|
/*
|
|
* If we're doing sack, check to
|
|
* see if we're already in sack
|
|
* recovery. If we're not doing sack,
|
|
* check to see if we're in newreno
|
|
* recovery.
|
|
*/
|
|
if (tp->t_flags & TF_SACK_PERMIT) {
|
|
if (IN_FASTRECOVERY(tp)) {
|
|
tp->t_dupacks = 0;
|
|
break;
|
|
}
|
|
} else if (V_tcp_do_newreno ||
|
|
V_tcp_do_ecn) {
|
|
if (SEQ_LEQ(th->th_ack,
|
|
tp->snd_recover)) {
|
|
tp->t_dupacks = 0;
|
|
break;
|
|
}
|
|
}
|
|
tcp_congestion_exp(tp);
|
|
tcp_timer_activate(tp, TT_REXMT, 0);
|
|
tp->t_rtttime = 0;
|
|
if (tp->t_flags & TF_SACK_PERMIT) {
|
|
TCPSTAT_INC(
|
|
tcps_sack_recovery_episode);
|
|
tp->sack_newdata = tp->snd_nxt;
|
|
tp->snd_cwnd = tp->t_maxseg;
|
|
(void) tcp_output(tp);
|
|
goto drop;
|
|
}
|
|
tp->snd_nxt = th->th_ack;
|
|
tp->snd_cwnd = tp->t_maxseg;
|
|
(void) tcp_output(tp);
|
|
KASSERT(tp->snd_limited <= 2,
|
|
("%s: tp->snd_limited too big",
|
|
__func__));
|
|
tp->snd_cwnd = tp->snd_ssthresh +
|
|
tp->t_maxseg *
|
|
(tp->t_dupacks - tp->snd_limited);
|
|
if (SEQ_GT(onxt, tp->snd_nxt))
|
|
tp->snd_nxt = onxt;
|
|
goto drop;
|
|
} else if (V_tcp_do_rfc3042) {
|
|
u_long oldcwnd = tp->snd_cwnd;
|
|
tcp_seq oldsndmax = tp->snd_max;
|
|
u_int sent;
|
|
|
|
KASSERT(tp->t_dupacks == 1 ||
|
|
tp->t_dupacks == 2,
|
|
("%s: dupacks not 1 or 2",
|
|
__func__));
|
|
if (tp->t_dupacks == 1)
|
|
tp->snd_limited = 0;
|
|
tp->snd_cwnd =
|
|
(tp->snd_nxt - tp->snd_una) +
|
|
(tp->t_dupacks - tp->snd_limited) *
|
|
tp->t_maxseg;
|
|
(void) tcp_output(tp);
|
|
sent = tp->snd_max - oldsndmax;
|
|
if (sent > tp->t_maxseg) {
|
|
KASSERT((tp->t_dupacks == 2 &&
|
|
tp->snd_limited == 0) ||
|
|
(sent == tp->t_maxseg + 1 &&
|
|
tp->t_flags & TF_SENTFIN),
|
|
("%s: sent too much",
|
|
__func__));
|
|
tp->snd_limited = 2;
|
|
} else if (sent > 0)
|
|
++tp->snd_limited;
|
|
tp->snd_cwnd = oldcwnd;
|
|
goto drop;
|
|
}
|
|
} else
|
|
tp->t_dupacks = 0;
|
|
break;
|
|
}
|
|
|
|
KASSERT(SEQ_GT(th->th_ack, tp->snd_una),
|
|
("%s: th_ack <= snd_una", __func__));
|
|
|
|
/*
|
|
* If the congestion window was inflated to account
|
|
* for the other side's cached packets, retract it.
|
|
*/
|
|
if (V_tcp_do_newreno || (tp->t_flags & TF_SACK_PERMIT)) {
|
|
if (IN_FASTRECOVERY(tp)) {
|
|
if (SEQ_LT(th->th_ack, tp->snd_recover)) {
|
|
if (tp->t_flags & TF_SACK_PERMIT)
|
|
tcp_sack_partialack(tp, th);
|
|
else
|
|
tcp_newreno_partial_ack(tp, th);
|
|
} else {
|
|
/*
|
|
* Out of fast recovery.
|
|
* Window inflation should have left us
|
|
* with approximately snd_ssthresh
|
|
* outstanding data.
|
|
* But in case we would be inclined to
|
|
* send a burst, better to do it via
|
|
* the slow start mechanism.
|
|
*/
|
|
if (SEQ_GT(th->th_ack +
|
|
tp->snd_ssthresh,
|
|
tp->snd_max))
|
|
tp->snd_cwnd = tp->snd_max -
|
|
th->th_ack +
|
|
tp->t_maxseg;
|
|
else
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
}
|
|
}
|
|
} else {
|
|
if (tp->t_dupacks >= tcprexmtthresh &&
|
|
tp->snd_cwnd > tp->snd_ssthresh)
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
}
|
|
tp->t_dupacks = 0;
|
|
/*
|
|
* If we reach this point, ACK is not a duplicate,
|
|
* i.e., it ACKs something we sent.
|
|
*/
|
|
if (tp->t_flags & TF_NEEDSYN) {
|
|
/*
|
|
* T/TCP: Connection was half-synchronized, and our
|
|
* SYN has been ACK'd (so connection is now fully
|
|
* synchronized). Go to non-starred state,
|
|
* increment snd_una for ACK of SYN, and check if
|
|
* we can do window scaling.
|
|
*/
|
|
tp->t_flags &= ~TF_NEEDSYN;
|
|
tp->snd_una++;
|
|
/* Do window scaling? */
|
|
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
|
|
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
|
|
tp->rcv_scale = tp->request_r_scale;
|
|
/* Send window already scaled. */
|
|
}
|
|
}
|
|
|
|
process_ACK:
|
|
INP_INFO_LOCK_ASSERT(&V_tcbinfo);
|
|
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
|
|
("tcp_input: process_ACK ti_locked %d", ti_locked));
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
acked = th->th_ack - tp->snd_una;
|
|
TCPSTAT_INC(tcps_rcvackpack);
|
|
TCPSTAT_ADD(tcps_rcvackbyte, acked);
|
|
|
|
/*
|
|
* If we just performed our first retransmit, and the ACK
|
|
* arrives within our recovery window, then it was a mistake
|
|
* to do the retransmit in the first place. Recover our
|
|
* original cwnd and ssthresh, and proceed to transmit where
|
|
* we left off.
|
|
*/
|
|
if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) {
|
|
TCPSTAT_INC(tcps_sndrexmitbad);
|
|
tp->snd_cwnd = tp->snd_cwnd_prev;
|
|
tp->snd_ssthresh = tp->snd_ssthresh_prev;
|
|
tp->snd_recover = tp->snd_recover_prev;
|
|
if (tp->t_flags & TF_WASFRECOVERY)
|
|
ENTER_FASTRECOVERY(tp);
|
|
tp->snd_nxt = tp->snd_max;
|
|
tp->t_badrxtwin = 0; /* XXX probably not required */
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* Some boxes send broken timestamp replies
|
|
* during the SYN+ACK phase, ignore
|
|
* timestamps of 0 or we could calculate a
|
|
* huge RTT and blow up the retransmit timer.
|
|
*/
|
|
if ((to.to_flags & TOF_TS) != 0 &&
|
|
to.to_tsecr) {
|
|
if (!tp->t_rttlow || tp->t_rttlow > ticks - to.to_tsecr)
|
|
tp->t_rttlow = ticks - to.to_tsecr;
|
|
tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
|
|
} else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) {
|
|
if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime)
|
|
tp->t_rttlow = ticks - tp->t_rtttime;
|
|
tcp_xmit_timer(tp, ticks - tp->t_rtttime);
|
|
}
|
|
tcp_xmit_bandwidth_limit(tp, th->th_ack);
|
|
|
|
/*
|
|
* 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_activate(tp, TT_REXMT, 0);
|
|
needoutput = 1;
|
|
} else if (!tcp_timer_active(tp, TT_PERSIST))
|
|
tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur);
|
|
|
|
/*
|
|
* If no data (only SYN) was ACK'd,
|
|
* skip rest of ACK processing.
|
|
*/
|
|
if (acked == 0)
|
|
goto step6;
|
|
|
|
/*
|
|
* When new data is acked, open the congestion window.
|
|
* Method depends on which congestion control state we're
|
|
* in (slow start or cong avoid) and if ABC (RFC 3465) is
|
|
* enabled.
|
|
*
|
|
* slow start: cwnd <= ssthresh
|
|
* cong avoid: cwnd > ssthresh
|
|
*
|
|
* slow start and ABC (RFC 3465):
|
|
* Grow cwnd exponentially by the amount of data
|
|
* ACKed capping the max increment per ACK to
|
|
* (abc_l_var * maxseg) bytes.
|
|
*
|
|
* slow start without ABC (RFC 2581):
|
|
* Grow cwnd exponentially by maxseg per ACK.
|
|
*
|
|
* cong avoid and ABC (RFC 3465):
|
|
* Grow cwnd linearly by maxseg per RTT for each
|
|
* cwnd worth of ACKed data.
|
|
*
|
|
* cong avoid without ABC (RFC 2581):
|
|
* Grow cwnd linearly by approximately maxseg per RTT using
|
|
* maxseg^2 / cwnd per ACK as the increment.
|
|
* If cwnd > maxseg^2, fix the cwnd increment at 1 byte to
|
|
* avoid capping cwnd.
|
|
*/
|
|
if ((!V_tcp_do_newreno && !(tp->t_flags & TF_SACK_PERMIT)) ||
|
|
!IN_FASTRECOVERY(tp)) {
|
|
u_int cw = tp->snd_cwnd;
|
|
u_int incr = tp->t_maxseg;
|
|
/* In congestion avoidance? */
|
|
if (cw > tp->snd_ssthresh) {
|
|
if (V_tcp_do_rfc3465) {
|
|
tp->t_bytes_acked += acked;
|
|
if (tp->t_bytes_acked >= tp->snd_cwnd)
|
|
tp->t_bytes_acked -= cw;
|
|
else
|
|
incr = 0;
|
|
}
|
|
else
|
|
incr = max((incr * incr / cw), 1);
|
|
/*
|
|
* In slow-start with ABC enabled and no RTO in sight?
|
|
* (Must not use abc_l_var > 1 if slow starting after an
|
|
* RTO. On RTO, snd_nxt = snd_una, so the snd_nxt ==
|
|
* snd_max check is sufficient to handle this).
|
|
*/
|
|
} else if (V_tcp_do_rfc3465 &&
|
|
tp->snd_nxt == tp->snd_max)
|
|
incr = min(acked,
|
|
V_tcp_abc_l_var * tp->t_maxseg);
|
|
/* ABC is on by default, so (incr == 0) frequently. */
|
|
if (incr > 0)
|
|
tp->snd_cwnd = min(cw+incr, TCP_MAXWIN<<tp->snd_scale);
|
|
}
|
|
SOCKBUF_LOCK(&so->so_snd);
|
|
if (acked > so->so_snd.sb_cc) {
|
|
tp->snd_wnd -= so->so_snd.sb_cc;
|
|
sbdrop_locked(&so->so_snd, (int)so->so_snd.sb_cc);
|
|
ourfinisacked = 1;
|
|
} else {
|
|
sbdrop_locked(&so->so_snd, acked);
|
|
tp->snd_wnd -= acked;
|
|
ourfinisacked = 0;
|
|
}
|
|
/* NB: sowwakeup_locked() does an implicit unlock. */
|
|
sowwakeup_locked(so);
|
|
/* Detect una wraparound. */
|
|
if ((V_tcp_do_newreno || (tp->t_flags & TF_SACK_PERMIT)) &&
|
|
!IN_FASTRECOVERY(tp) &&
|
|
SEQ_GT(tp->snd_una, tp->snd_recover) &&
|
|
SEQ_LEQ(th->th_ack, tp->snd_recover))
|
|
tp->snd_recover = th->th_ack - 1;
|
|
if ((V_tcp_do_newreno || (tp->t_flags & TF_SACK_PERMIT)) &&
|
|
IN_FASTRECOVERY(tp) &&
|
|
SEQ_GEQ(th->th_ack, tp->snd_recover)) {
|
|
EXIT_FASTRECOVERY(tp);
|
|
tp->t_bytes_acked = 0;
|
|
}
|
|
tp->snd_una = th->th_ack;
|
|
if (tp->t_flags & TF_SACK_PERMIT) {
|
|
if (SEQ_GT(tp->snd_una, tp->snd_recover))
|
|
tp->snd_recover = tp->snd_una;
|
|
}
|
|
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
|
tp->snd_nxt = tp->snd_una;
|
|
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* In FIN_WAIT_1 STATE in addition to the processing
|
|
* for the ESTABLISHED state if our FIN is now acknowledged
|
|
* then enter FIN_WAIT_2.
|
|
*/
|
|
case TCPS_FIN_WAIT_1:
|
|
if (ourfinisacked) {
|
|
/*
|
|
* If we can't receive any more
|
|
* data, then closing user can proceed.
|
|
* Starting the timer is contrary to the
|
|
* specification, but if we don't get a FIN
|
|
* we'll hang forever.
|
|
*
|
|
* XXXjl:
|
|
* we should release the tp also, and use a
|
|
* compressed state.
|
|
*/
|
|
if (so->so_rcv.sb_state & SBS_CANTRCVMORE) {
|
|
int timeout;
|
|
|
|
soisdisconnected(so);
|
|
timeout = (tcp_fast_finwait2_recycle) ?
|
|
tcp_finwait2_timeout : tcp_maxidle;
|
|
tcp_timer_activate(tp, TT_2MSL, timeout);
|
|
}
|
|
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) {
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
tcp_twstart(tp);
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
m_freem(m);
|
|
return;
|
|
}
|
|
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) {
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
tp = tcp_close(tp);
|
|
goto drop;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
step6:
|
|
INP_INFO_LOCK_ASSERT(&V_tcbinfo);
|
|
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
|
|
("tcp_do_segment: step6 ti_locked %d", ti_locked));
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
/*
|
|
* Update window information.
|
|
* Don't look at window if no ACK: TAC's send garbage on first SYN.
|
|
*/
|
|
if ((thflags & TH_ACK) &&
|
|
(SEQ_LT(tp->snd_wl1, th->th_seq) ||
|
|
(tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) ||
|
|
(tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) {
|
|
/* keep track of pure window updates */
|
|
if (tlen == 0 &&
|
|
tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)
|
|
TCPSTAT_INC(tcps_rcvwinupd);
|
|
tp->snd_wnd = tiwin;
|
|
tp->snd_wl1 = th->th_seq;
|
|
tp->snd_wl2 = th->th_ack;
|
|
if (tp->snd_wnd > tp->max_sndwnd)
|
|
tp->max_sndwnd = tp->snd_wnd;
|
|
needoutput = 1;
|
|
}
|
|
|
|
/*
|
|
* Process segments with URG.
|
|
*/
|
|
if ((thflags & 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.
|
|
*/
|
|
SOCKBUF_LOCK(&so->so_rcv);
|
|
if (th->th_urp + so->so_rcv.sb_cc > sb_max) {
|
|
th->th_urp = 0; /* XXX */
|
|
thflags &= ~TH_URG; /* XXX */
|
|
SOCKBUF_UNLOCK(&so->so_rcv); /* 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_rcv.sb_state |= SBS_RCVATMARK;
|
|
sohasoutofband(so);
|
|
tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
|
|
}
|
|
SOCKBUF_UNLOCK(&so->so_rcv);
|
|
/*
|
|
* 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_long)tlen &&
|
|
!(so->so_options & SO_OOBINLINE)) {
|
|
/* hdr drop is delayed */
|
|
tcp_pulloutofband(so, th, m, drop_hdrlen);
|
|
}
|
|
} else {
|
|
/*
|
|
* If no out of band data is expected,
|
|
* pull receive urgent pointer along
|
|
* with the receive window.
|
|
*/
|
|
if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
|
|
tp->rcv_up = tp->rcv_nxt;
|
|
}
|
|
dodata: /* XXX */
|
|
INP_INFO_LOCK_ASSERT(&V_tcbinfo);
|
|
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
|
|
("tcp_do_segment: dodata ti_locked %d", ti_locked));
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
/*
|
|
* Process the segment text, merging it into the TCP sequencing queue,
|
|
* and arranging for acknowledgment of receipt if necessary.
|
|
* This process logically involves adjusting tp->rcv_wnd as data
|
|
* is presented to the user (this happens in tcp_usrreq.c,
|
|
* case PRU_RCVD). If a FIN has already been received on this
|
|
* connection then we just ignore the text.
|
|
*/
|
|
if ((tlen || (thflags & TH_FIN)) &&
|
|
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
|
tcp_seq save_start = th->th_seq;
|
|
m_adj(m, drop_hdrlen); /* delayed header drop */
|
|
/*
|
|
* Insert segment which includes th into TCP reassembly queue
|
|
* with control block tp. Set thflags to whether reassembly now
|
|
* includes a segment with FIN. This handles the common case
|
|
* inline (segment is the next to be received on an established
|
|
* connection, and the queue is empty), avoiding linkage into
|
|
* and removal from the queue and repetition of various
|
|
* conversions.
|
|
* Set DELACK for segments received in order, but ack
|
|
* immediately when segments are out of order (so
|
|
* fast retransmit can work).
|
|
*/
|
|
if (th->th_seq == tp->rcv_nxt &&
|
|
LIST_EMPTY(&tp->t_segq) &&
|
|
TCPS_HAVEESTABLISHED(tp->t_state)) {
|
|
if (DELAY_ACK(tp))
|
|
tp->t_flags |= TF_DELACK;
|
|
else
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tp->rcv_nxt += tlen;
|
|
thflags = th->th_flags & TH_FIN;
|
|
TCPSTAT_INC(tcps_rcvpack);
|
|
TCPSTAT_ADD(tcps_rcvbyte, tlen);
|
|
ND6_HINT(tp);
|
|
SOCKBUF_LOCK(&so->so_rcv);
|
|
if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
|
|
m_freem(m);
|
|
else
|
|
sbappendstream_locked(&so->so_rcv, m);
|
|
/* NB: sorwakeup_locked() does an implicit unlock. */
|
|
sorwakeup_locked(so);
|
|
} else {
|
|
/*
|
|
* XXX: Due to the header drop above "th" is
|
|
* theoretically invalid by now. Fortunately
|
|
* m_adj() doesn't actually frees any mbufs
|
|
* when trimming from the head.
|
|
*/
|
|
thflags = tcp_reass(tp, th, &tlen, m);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
}
|
|
if (tlen > 0 && (tp->t_flags & TF_SACK_PERMIT))
|
|
tcp_update_sack_list(tp, save_start, save_start + tlen);
|
|
#if 0
|
|
/*
|
|
* Note the amount of data that peer has sent into
|
|
* our window, in order to estimate the sender's
|
|
* buffer size.
|
|
* XXX: Unused.
|
|
*/
|
|
len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
|
|
#endif
|
|
} else {
|
|
m_freem(m);
|
|
thflags &= ~TH_FIN;
|
|
}
|
|
|
|
/*
|
|
* If FIN is received ACK the FIN and let the user know
|
|
* that the connection is closing.
|
|
*/
|
|
if (thflags & TH_FIN) {
|
|
if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
|
socantrcvmore(so);
|
|
/*
|
|
* If connection is half-synchronized
|
|
* (ie NEEDSYN flag on) then delay ACK,
|
|
* so it may be piggybacked when SYN is sent.
|
|
* Otherwise, since we received a FIN then no
|
|
* more input can be expected, send ACK now.
|
|
*/
|
|
if (tp->t_flags & TF_NEEDSYN)
|
|
tp->t_flags |= TF_DELACK;
|
|
else
|
|
tp->t_flags |= TF_ACKNOW;
|
|
tp->rcv_nxt++;
|
|
}
|
|
switch (tp->t_state) {
|
|
|
|
/*
|
|
* In SYN_RECEIVED and ESTABLISHED STATES
|
|
* enter the CLOSE_WAIT state.
|
|
*/
|
|
case TCPS_SYN_RECEIVED:
|
|
tp->t_starttime = ticks;
|
|
/* FALLTHROUGH */
|
|
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:
|
|
INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
|
|
KASSERT(ti_locked == TI_WLOCKED, ("%s: dodata "
|
|
"TCP_FIN_WAIT_2 ti_locked: %d", __func__,
|
|
ti_locked));
|
|
|
|
tcp_twstart(tp);
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
return;
|
|
}
|
|
}
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: dodata epilogue ti_locked %d", __func__,
|
|
ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
#ifdef TCPDEBUG
|
|
if (so->so_options & SO_DEBUG)
|
|
tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen,
|
|
&tcp_savetcp, 0);
|
|
#endif
|
|
|
|
/*
|
|
* Return any desired output.
|
|
*/
|
|
if (needoutput || (tp->t_flags & TF_ACKNOW))
|
|
(void) tcp_output(tp);
|
|
|
|
check_delack:
|
|
KASSERT(ti_locked == TI_UNLOCKED, ("%s: check_delack ti_locked %d",
|
|
__func__, ti_locked));
|
|
INP_INFO_UNLOCK_ASSERT(&V_tcbinfo);
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
if (tp->t_flags & TF_DELACK) {
|
|
tp->t_flags &= ~TF_DELACK;
|
|
tcp_timer_activate(tp, TT_DELACK, tcp_delacktime);
|
|
}
|
|
INP_WUNLOCK(tp->t_inpcb);
|
|
return;
|
|
|
|
dropafterack:
|
|
KASSERT(ti_locked == TI_RLOCKED || ti_locked == TI_WLOCKED,
|
|
("tcp_do_segment: dropafterack ti_locked %d", ti_locked));
|
|
|
|
/*
|
|
* Generate an ACK dropping incoming segment if it occupies
|
|
* sequence space, where the ACK reflects our state.
|
|
*
|
|
* We can now skip the test for the RST flag since all
|
|
* paths to this code happen after packets containing
|
|
* RST have been dropped.
|
|
*
|
|
* In the SYN-RECEIVED state, don't send an ACK unless the
|
|
* segment we received passes the SYN-RECEIVED ACK test.
|
|
* If it fails send a RST. This breaks the loop in the
|
|
* "LAND" DoS attack, and also prevents an ACK storm
|
|
* between two listening ports that have been sent forged
|
|
* SYN segments, each with the source address of the other.
|
|
*/
|
|
if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) &&
|
|
(SEQ_GT(tp->snd_una, th->th_ack) ||
|
|
SEQ_GT(th->th_ack, tp->snd_max)) ) {
|
|
rstreason = BANDLIM_RST_OPENPORT;
|
|
goto dropwithreset;
|
|
}
|
|
#ifdef TCPDEBUG
|
|
if (so->so_options & SO_DEBUG)
|
|
tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen,
|
|
&tcp_savetcp, 0);
|
|
#endif
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: dropafterack epilogue ti_locked %d", __func__,
|
|
ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
tp->t_flags |= TF_ACKNOW;
|
|
(void) tcp_output(tp);
|
|
INP_WUNLOCK(tp->t_inpcb);
|
|
m_freem(m);
|
|
return;
|
|
|
|
dropwithreset:
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
else
|
|
panic("%s: dropwithreset ti_locked %d", __func__, ti_locked);
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
if (tp != NULL) {
|
|
tcp_dropwithreset(m, th, tp, tlen, rstreason);
|
|
INP_WUNLOCK(tp->t_inpcb);
|
|
} else
|
|
tcp_dropwithreset(m, th, NULL, tlen, rstreason);
|
|
return;
|
|
|
|
drop:
|
|
if (ti_locked == TI_RLOCKED)
|
|
INP_INFO_RUNLOCK(&V_tcbinfo);
|
|
else if (ti_locked == TI_WLOCKED)
|
|
INP_INFO_WUNLOCK(&V_tcbinfo);
|
|
#ifdef INVARIANTS
|
|
else
|
|
INP_INFO_UNLOCK_ASSERT(&V_tcbinfo);
|
|
#endif
|
|
ti_locked = TI_UNLOCKED;
|
|
|
|
/*
|
|
* Drop space held by incoming segment and return.
|
|
*/
|
|
#ifdef TCPDEBUG
|
|
if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
|
|
tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen,
|
|
&tcp_savetcp, 0);
|
|
#endif
|
|
if (tp != NULL)
|
|
INP_WUNLOCK(tp->t_inpcb);
|
|
m_freem(m);
|
|
}
|
|
|
|
/*
|
|
* Issue RST and make ACK acceptable to originator of segment.
|
|
* The mbuf must still include the original packet header.
|
|
* tp may be NULL.
|
|
*/
|
|
static void
|
|
tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp,
|
|
int tlen, int rstreason)
|
|
{
|
|
struct ip *ip;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6;
|
|
#endif
|
|
|
|
if (tp != NULL) {
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
}
|
|
|
|
/* Don't bother if destination was broadcast/multicast. */
|
|
if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST))
|
|
goto drop;
|
|
#ifdef INET6
|
|
if (mtod(m, struct ip *)->ip_v == 6) {
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
|
|
IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
|
|
goto drop;
|
|
/* IPv6 anycast check is done at tcp6_input() */
|
|
} else
|
|
#endif
|
|
{
|
|
ip = mtod(m, struct ip *);
|
|
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
|
|
IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
|
|
ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
|
|
in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
|
|
goto drop;
|
|
}
|
|
|
|
/* Perform bandwidth limiting. */
|
|
if (badport_bandlim(rstreason) < 0)
|
|
goto drop;
|
|
|
|
/* tcp_respond consumes the mbuf chain. */
|
|
if (th->th_flags & TH_ACK) {
|
|
tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0,
|
|
th->th_ack, TH_RST);
|
|
} else {
|
|
if (th->th_flags & TH_SYN)
|
|
tlen++;
|
|
tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen,
|
|
(tcp_seq)0, TH_RST|TH_ACK);
|
|
}
|
|
return;
|
|
drop:
|
|
m_freem(m);
|
|
}
|
|
|
|
/*
|
|
* Parse TCP options and place in tcpopt.
|
|
*/
|
|
static void
|
|
tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags)
|
|
{
|
|
INIT_VNET_INET(curvnet);
|
|
int opt, optlen;
|
|
|
|
to->to_flags = 0;
|
|
for (; 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) {
|
|
case TCPOPT_MAXSEG:
|
|
if (optlen != TCPOLEN_MAXSEG)
|
|
continue;
|
|
if (!(flags & TO_SYN))
|
|
continue;
|
|
to->to_flags |= TOF_MSS;
|
|
bcopy((char *)cp + 2,
|
|
(char *)&to->to_mss, sizeof(to->to_mss));
|
|
to->to_mss = ntohs(to->to_mss);
|
|
break;
|
|
case TCPOPT_WINDOW:
|
|
if (optlen != TCPOLEN_WINDOW)
|
|
continue;
|
|
if (!(flags & TO_SYN))
|
|
continue;
|
|
to->to_flags |= TOF_SCALE;
|
|
to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT);
|
|
break;
|
|
case TCPOPT_TIMESTAMP:
|
|
if (optlen != TCPOLEN_TIMESTAMP)
|
|
continue;
|
|
to->to_flags |= TOF_TS;
|
|
bcopy((char *)cp + 2,
|
|
(char *)&to->to_tsval, sizeof(to->to_tsval));
|
|
to->to_tsval = ntohl(to->to_tsval);
|
|
bcopy((char *)cp + 6,
|
|
(char *)&to->to_tsecr, sizeof(to->to_tsecr));
|
|
to->to_tsecr = ntohl(to->to_tsecr);
|
|
break;
|
|
#ifdef TCP_SIGNATURE
|
|
/*
|
|
* XXX In order to reply to a host which has set the
|
|
* TCP_SIGNATURE option in its initial SYN, we have to
|
|
* record the fact that the option was observed here
|
|
* for the syncache code to perform the correct response.
|
|
*/
|
|
case TCPOPT_SIGNATURE:
|
|
if (optlen != TCPOLEN_SIGNATURE)
|
|
continue;
|
|
to->to_flags |= TOF_SIGNATURE;
|
|
to->to_signature = cp + 2;
|
|
break;
|
|
#endif
|
|
case TCPOPT_SACK_PERMITTED:
|
|
if (optlen != TCPOLEN_SACK_PERMITTED)
|
|
continue;
|
|
if (!(flags & TO_SYN))
|
|
continue;
|
|
if (!V_tcp_do_sack)
|
|
continue;
|
|
to->to_flags |= TOF_SACKPERM;
|
|
break;
|
|
case TCPOPT_SACK:
|
|
if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0)
|
|
continue;
|
|
if (flags & TO_SYN)
|
|
continue;
|
|
to->to_flags |= TOF_SACK;
|
|
to->to_nsacks = (optlen - 2) / TCPOLEN_SACK;
|
|
to->to_sacks = cp + 2;
|
|
TCPSTAT_INC(tcps_sack_rcv_blocks);
|
|
break;
|
|
default:
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static 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, caddr_t) + cnt;
|
|
struct tcpcb *tp = sototcpcb(so);
|
|
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
tp->t_iobc = *cp;
|
|
tp->t_oobflags |= TCPOOB_HAVEDATA;
|
|
bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1));
|
|
m->m_len--;
|
|
if (m->m_flags & M_PKTHDR)
|
|
m->m_pkthdr.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.
|
|
*/
|
|
static void
|
|
tcp_xmit_timer(struct tcpcb *tp, int rtt)
|
|
{
|
|
INIT_VNET_INET(tp->t_inpcb->inp_vnet);
|
|
int delta;
|
|
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
TCPSTAT_INC(tcps_rttupdated);
|
|
tp->t_rttupdated++;
|
|
if (tp->t_srtt != 0) {
|
|
/*
|
|
* srtt is stored as fixed point with 5 bits after the
|
|
* binary point (i.e., scaled by 8). The following magic
|
|
* is equivalent to the smoothing algorithm in rfc793 with
|
|
* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
|
|
* point). Adjust rtt to origin 0.
|
|
*/
|
|
delta = ((rtt - 1) << TCP_DELTA_SHIFT)
|
|
- (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
|
|
|
|
if ((tp->t_srtt += delta) <= 0)
|
|
tp->t_srtt = 1;
|
|
|
|
/*
|
|
* We accumulate a smoothed rtt variance (actually, a
|
|
* smoothed mean difference), then set the retransmit
|
|
* timer to smoothed rtt + 4 times the smoothed variance.
|
|
* rttvar is stored as fixed point with 4 bits after the
|
|
* binary point (scaled by 16). The following is
|
|
* equivalent to rfc793 smoothing with an alpha of .75
|
|
* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
|
|
* rfc793's wired-in beta.
|
|
*/
|
|
if (delta < 0)
|
|
delta = -delta;
|
|
delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
|
|
if ((tp->t_rttvar += delta) <= 0)
|
|
tp->t_rttvar = 1;
|
|
if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
|
|
tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
|
|
} else {
|
|
/*
|
|
* No rtt measurement yet - use the unsmoothed rtt.
|
|
* Set the variance to half the rtt (so our first
|
|
* retransmit happens at 3*rtt).
|
|
*/
|
|
tp->t_srtt = rtt << TCP_RTT_SHIFT;
|
|
tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
|
|
tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
|
|
}
|
|
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),
|
|
max(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;
|
|
}
|
|
|
|
/*
|
|
* Determine a reasonable value for maxseg size.
|
|
* If the route is known, check route for mtu.
|
|
* If none, use an mss that can be handled on the outgoing
|
|
* interface without forcing IP to fragment; if bigger than
|
|
* an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
|
|
* to utilize large mbufs. If no route is found, route has no mtu,
|
|
* or the destination isn't local, use a default, hopefully conservative
|
|
* size (usually 512 or the default IP max size, but no more than the mtu
|
|
* of the interface), as we can't discover anything about intervening
|
|
* gateways or networks. We also initialize the congestion/slow start
|
|
* window to be a single segment if the destination isn't local.
|
|
* While looking at the routing entry, we also initialize other path-dependent
|
|
* parameters from pre-set or cached values in the routing entry.
|
|
*
|
|
* Also take into account the space needed for options that we
|
|
* send regularly. Make maxseg shorter by that amount to assure
|
|
* that we can send maxseg amount of data even when the options
|
|
* are present. Store the upper limit of the length of options plus
|
|
* data in maxopd.
|
|
*
|
|
* In case of T/TCP, we call this routine during implicit connection
|
|
* setup as well (offer = -1), to initialize maxseg from the cached
|
|
* MSS of our peer.
|
|
*
|
|
* NOTE that this routine is only called when we process an incoming
|
|
* segment. Outgoing SYN/ACK MSS settings are handled in tcp_mssopt().
|
|
*/
|
|
void
|
|
tcp_mss_update(struct tcpcb *tp, int offer,
|
|
struct hc_metrics_lite *metricptr, int *mtuflags)
|
|
{
|
|
INIT_VNET_INET(tp->t_inpcb->inp_vnet);
|
|
int mss;
|
|
u_long maxmtu;
|
|
struct inpcb *inp = tp->t_inpcb;
|
|
struct hc_metrics_lite metrics;
|
|
int origoffer = offer;
|
|
#ifdef INET6
|
|
int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0;
|
|
size_t min_protoh = isipv6 ?
|
|
sizeof (struct ip6_hdr) + sizeof (struct tcphdr) :
|
|
sizeof (struct tcpiphdr);
|
|
#else
|
|
const size_t min_protoh = sizeof(struct tcpiphdr);
|
|
#endif
|
|
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
/* Initialize. */
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
maxmtu = tcp_maxmtu6(&inp->inp_inc, mtuflags);
|
|
tp->t_maxopd = tp->t_maxseg = V_tcp_v6mssdflt;
|
|
} else
|
|
#endif
|
|
{
|
|
maxmtu = tcp_maxmtu(&inp->inp_inc, mtuflags);
|
|
tp->t_maxopd = tp->t_maxseg = V_tcp_mssdflt;
|
|
}
|
|
|
|
/*
|
|
* No route to sender, stay with default mss and return.
|
|
*/
|
|
if (maxmtu == 0) {
|
|
/*
|
|
* In case we return early we need to initialize metrics
|
|
* to a defined state as tcp_hc_get() would do for us
|
|
* if there was no cache hit.
|
|
*/
|
|
if (metricptr != NULL)
|
|
bzero(metricptr, sizeof(struct hc_metrics_lite));
|
|
return;
|
|
}
|
|
|
|
/* What have we got? */
|
|
switch (offer) {
|
|
case 0:
|
|
/*
|
|
* Offer == 0 means that there was no MSS on the SYN
|
|
* segment, in this case we use tcp_mssdflt as
|
|
* already assigned to t_maxopd above.
|
|
*/
|
|
offer = tp->t_maxopd;
|
|
break;
|
|
|
|
case -1:
|
|
/*
|
|
* Offer == -1 means that we didn't receive SYN yet.
|
|
*/
|
|
/* FALLTHROUGH */
|
|
|
|
default:
|
|
/*
|
|
* Prevent DoS attack with too small MSS. Round up
|
|
* to at least minmss.
|
|
*/
|
|
offer = max(offer, V_tcp_minmss);
|
|
}
|
|
|
|
/*
|
|
* rmx information is now retrieved from tcp_hostcache.
|
|
*/
|
|
tcp_hc_get(&inp->inp_inc, &metrics);
|
|
if (metricptr != NULL)
|
|
bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite));
|
|
|
|
/*
|
|
* If there's a discovered mtu int tcp hostcache, use it
|
|
* else, use the link mtu.
|
|
*/
|
|
if (metrics.rmx_mtu)
|
|
mss = min(metrics.rmx_mtu, maxmtu) - min_protoh;
|
|
else {
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
mss = maxmtu - min_protoh;
|
|
if (!V_path_mtu_discovery &&
|
|
!in6_localaddr(&inp->in6p_faddr))
|
|
mss = min(mss, V_tcp_v6mssdflt);
|
|
} else
|
|
#endif
|
|
{
|
|
mss = maxmtu - min_protoh;
|
|
if (!V_path_mtu_discovery &&
|
|
!in_localaddr(inp->inp_faddr))
|
|
mss = min(mss, V_tcp_mssdflt);
|
|
}
|
|
/*
|
|
* XXX - The above conditional (mss = maxmtu - min_protoh)
|
|
* probably violates the TCP spec.
|
|
* The problem is that, since we don't know the
|
|
* other end's MSS, we are supposed to use a conservative
|
|
* default. But, if we do that, then MTU discovery will
|
|
* never actually take place, because the conservative
|
|
* default is much less than the MTUs typically seen
|
|
* on the Internet today. For the moment, we'll sweep
|
|
* this under the carpet.
|
|
*
|
|
* The conservative default might not actually be a problem
|
|
* if the only case this occurs is when sending an initial
|
|
* SYN with options and data to a host we've never talked
|
|
* to before. Then, they will reply with an MSS value which
|
|
* will get recorded and the new parameters should get
|
|
* recomputed. For Further Study.
|
|
*/
|
|
}
|
|
mss = min(mss, offer);
|
|
|
|
/*
|
|
* Sanity check: make sure that maxopd will be large
|
|
* enough to allow some data on segments even if the
|
|
* all the option space is used (40bytes). Otherwise
|
|
* funny things may happen in tcp_output.
|
|
*/
|
|
mss = max(mss, 64);
|
|
|
|
/*
|
|
* maxopd stores the maximum length of data AND options
|
|
* in a segment; maxseg is the amount of data in a normal
|
|
* segment. We need to store this value (maxopd) apart
|
|
* from maxseg, because now every segment carries options
|
|
* and thus we normally have somewhat less data in segments.
|
|
*/
|
|
tp->t_maxopd = mss;
|
|
|
|
/*
|
|
* origoffer==-1 indicates that no segments were received yet.
|
|
* In this case we just guess.
|
|
*/
|
|
if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
|
|
(origoffer == -1 ||
|
|
(tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
|
|
mss -= TCPOLEN_TSTAMP_APPA;
|
|
|
|
#if (MCLBYTES & (MCLBYTES - 1)) == 0
|
|
if (mss > MCLBYTES)
|
|
mss &= ~(MCLBYTES-1);
|
|
#else
|
|
if (mss > MCLBYTES)
|
|
mss = mss / MCLBYTES * MCLBYTES;
|
|
#endif
|
|
tp->t_maxseg = mss;
|
|
}
|
|
|
|
void
|
|
tcp_mss(struct tcpcb *tp, int offer)
|
|
{
|
|
int rtt, mss;
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u_long bufsize;
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struct inpcb *inp;
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struct socket *so;
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struct hc_metrics_lite metrics;
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int mtuflags = 0;
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#ifdef INET6
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int isipv6;
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#endif
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KASSERT(tp != NULL, ("%s: tp == NULL", __func__));
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INIT_VNET_INET(tp->t_vnet);
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tcp_mss_update(tp, offer, &metrics, &mtuflags);
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mss = tp->t_maxseg;
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inp = tp->t_inpcb;
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#ifdef INET6
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isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0;
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#endif
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/*
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* If there's a pipesize, change the socket buffer to that size,
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* don't change if sb_hiwat is different than default (then it
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* has been changed on purpose with setsockopt).
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* Make the socket buffers an integral number of mss units;
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* if the mss is larger than the socket buffer, decrease the mss.
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*/
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so = inp->inp_socket;
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SOCKBUF_LOCK(&so->so_snd);
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if ((so->so_snd.sb_hiwat == tcp_sendspace) && metrics.rmx_sendpipe)
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bufsize = metrics.rmx_sendpipe;
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else
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bufsize = so->so_snd.sb_hiwat;
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if (bufsize < mss)
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mss = bufsize;
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else {
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bufsize = roundup(bufsize, mss);
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if (bufsize > sb_max)
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bufsize = sb_max;
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if (bufsize > so->so_snd.sb_hiwat)
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(void)sbreserve_locked(&so->so_snd, bufsize, so, NULL);
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}
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SOCKBUF_UNLOCK(&so->so_snd);
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tp->t_maxseg = mss;
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SOCKBUF_LOCK(&so->so_rcv);
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if ((so->so_rcv.sb_hiwat == tcp_recvspace) && metrics.rmx_recvpipe)
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bufsize = metrics.rmx_recvpipe;
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else
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bufsize = so->so_rcv.sb_hiwat;
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if (bufsize > mss) {
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bufsize = roundup(bufsize, mss);
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if (bufsize > sb_max)
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bufsize = sb_max;
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if (bufsize > so->so_rcv.sb_hiwat)
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(void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL);
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}
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SOCKBUF_UNLOCK(&so->so_rcv);
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/*
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* While we're here, check the others too.
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*/
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if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) {
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tp->t_srtt = rtt;
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tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE;
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TCPSTAT_INC(tcps_usedrtt);
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if (metrics.rmx_rttvar) {
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tp->t_rttvar = metrics.rmx_rttvar;
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TCPSTAT_INC(tcps_usedrttvar);
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} else {
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/* default variation is +- 1 rtt */
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tp->t_rttvar =
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tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
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}
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TCPT_RANGESET(tp->t_rxtcur,
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((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
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tp->t_rttmin, TCPTV_REXMTMAX);
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}
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if (metrics.rmx_ssthresh) {
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/*
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* There's some sort of gateway or interface
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* buffer limit on the path. Use this to set
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* the slow start threshhold, but set the
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* threshold to no less than 2*mss.
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*/
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tp->snd_ssthresh = max(2 * mss, metrics.rmx_ssthresh);
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TCPSTAT_INC(tcps_usedssthresh);
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}
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if (metrics.rmx_bandwidth)
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tp->snd_bandwidth = metrics.rmx_bandwidth;
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/*
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* Set the slow-start flight size depending on whether this
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* is a local network or not.
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*
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* Extend this so we cache the cwnd too and retrieve it here.
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* Make cwnd even bigger than RFC3390 suggests but only if we
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* have previous experience with the remote host. Be careful
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* not make cwnd bigger than remote receive window or our own
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* send socket buffer. Maybe put some additional upper bound
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* on the retrieved cwnd. Should do incremental updates to
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* hostcache when cwnd collapses so next connection doesn't
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* overloads the path again.
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*
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* RFC3390 says only do this if SYN or SYN/ACK didn't got lost.
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* We currently check only in syncache_socket for that.
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*/
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#define TCP_METRICS_CWND
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#ifdef TCP_METRICS_CWND
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if (metrics.rmx_cwnd)
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tp->snd_cwnd = max(mss,
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min(metrics.rmx_cwnd / 2,
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min(tp->snd_wnd, so->so_snd.sb_hiwat)));
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else
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#endif
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if (V_tcp_do_rfc3390)
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tp->snd_cwnd = min(4 * mss, max(2 * mss, 4380));
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#ifdef INET6
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else if ((isipv6 && in6_localaddr(&inp->in6p_faddr)) ||
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(!isipv6 && in_localaddr(inp->inp_faddr)))
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#else
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else if (in_localaddr(inp->inp_faddr))
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#endif
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tp->snd_cwnd = mss * V_ss_fltsz_local;
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else
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tp->snd_cwnd = mss * V_ss_fltsz;
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/* Check the interface for TSO capabilities. */
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if (mtuflags & CSUM_TSO)
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tp->t_flags |= TF_TSO;
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}
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|
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/*
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* Determine the MSS option to send on an outgoing SYN.
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*/
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int
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tcp_mssopt(struct in_conninfo *inc)
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{
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INIT_VNET_INET(curvnet);
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int mss = 0;
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u_long maxmtu = 0;
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u_long thcmtu = 0;
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size_t min_protoh;
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KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer"));
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#ifdef INET6
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if (inc->inc_flags & INC_ISIPV6) {
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mss = V_tcp_v6mssdflt;
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maxmtu = tcp_maxmtu6(inc, NULL);
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thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */
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min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
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} else
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#endif
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{
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mss = V_tcp_mssdflt;
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maxmtu = tcp_maxmtu(inc, NULL);
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thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */
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min_protoh = sizeof(struct tcpiphdr);
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}
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if (maxmtu && thcmtu)
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mss = min(maxmtu, thcmtu) - min_protoh;
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else if (maxmtu || thcmtu)
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mss = max(maxmtu, thcmtu) - min_protoh;
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return (mss);
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}
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|
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|
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/*
|
|
* On a partial ack arrives, force the retransmission of the
|
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* next unacknowledged segment. Do not clear tp->t_dupacks.
|
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* By setting snd_nxt to ti_ack, this forces retransmission timer to
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* be started again.
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*/
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static void
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tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th)
|
|
{
|
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tcp_seq onxt = tp->snd_nxt;
|
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u_long ocwnd = tp->snd_cwnd;
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|
|
|
INP_WLOCK_ASSERT(tp->t_inpcb);
|
|
|
|
tcp_timer_activate(tp, TT_REXMT, 0);
|
|
tp->t_rtttime = 0;
|
|
tp->snd_nxt = th->th_ack;
|
|
/*
|
|
* Set snd_cwnd to one segment beyond acknowledged offset.
|
|
* (tp->snd_una has not yet been updated when this function is called.)
|
|
*/
|
|
tp->snd_cwnd = tp->t_maxseg + (th->th_ack - tp->snd_una);
|
|
tp->t_flags |= TF_ACKNOW;
|
|
(void) tcp_output(tp);
|
|
tp->snd_cwnd = ocwnd;
|
|
if (SEQ_GT(onxt, tp->snd_nxt))
|
|
tp->snd_nxt = onxt;
|
|
/*
|
|
* Partial window deflation. Relies on fact that tp->snd_una
|
|
* not updated yet.
|
|
*/
|
|
if (tp->snd_cwnd > th->th_ack - tp->snd_una)
|
|
tp->snd_cwnd -= th->th_ack - tp->snd_una;
|
|
else
|
|
tp->snd_cwnd = 0;
|
|
tp->snd_cwnd += tp->t_maxseg;
|
|
}
|