752 lines
20 KiB
C
752 lines
20 KiB
C
/*
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
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* $Id: tcp_subr.c,v 1.48 1998/11/15 21:35:09 guido Exp $
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*/
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#include "opt_compat.h"
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#include "opt_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/protosw.h>
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#include <vm/vm_zone.h>
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#include <net/route.h>
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#include <net/if.h>
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#define _IP_VHL
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_pcb.h>
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#include <netinet/in_var.h>
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#include <netinet/ip_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet/tcpip.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif
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int tcp_mssdflt = TCP_MSS;
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SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
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CTLFLAG_RW, &tcp_mssdflt , 0, "");
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static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
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SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt,
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CTLFLAG_RW, &tcp_rttdflt , 0, "");
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static int tcp_do_rfc1323 = 1;
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SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323,
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CTLFLAG_RW, &tcp_do_rfc1323 , 0, "");
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static int tcp_do_rfc1644 = 0;
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SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644,
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CTLFLAG_RW, &tcp_do_rfc1644 , 0, "");
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, &tcbinfo.ipi_count,
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0, "Number of active PCBs");
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static void tcp_cleartaocache __P((void));
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static void tcp_notify __P((struct inpcb *, int));
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/*
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* Target size of TCP PCB hash tables. Must be a power of two.
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*/
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#ifndef TCBHASHSIZE
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#define TCBHASHSIZE 512
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#endif
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/*
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* This is the actual shape of what we allocate using the zone
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* allocator. Doing it this way allows us to protect both structures
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* using the same generation count, and also eliminates the overhead
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* of allocating tcpcbs separately. By hiding the structure here,
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* we avoid changing most of the rest of the code (although it needs
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* to be changed, eventually, for greater efficiency).
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*/
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#define ALIGNMENT 32
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#define ALIGNM1 (ALIGNMENT - 1)
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struct inp_tp {
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union {
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struct inpcb inp;
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char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1];
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} inp_tp_u;
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struct tcpcb tcb;
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};
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#undef ALIGNMENT
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#undef ALIGNM1
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/*
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* Tcp initialization
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*/
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void
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tcp_init()
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{
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tcp_iss = random(); /* wrong, but better than a constant */
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tcp_ccgen = 1;
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tcp_cleartaocache();
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LIST_INIT(&tcb);
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tcbinfo.listhead = &tcb;
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tcbinfo.hashbase = hashinit(TCBHASHSIZE, M_PCB, &tcbinfo.hashmask);
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tcbinfo.porthashbase = hashinit(TCBHASHSIZE, M_PCB,
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&tcbinfo.porthashmask);
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tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets,
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ZONE_INTERRUPT, 0);
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if (max_protohdr < sizeof(struct tcpiphdr))
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max_protohdr = sizeof(struct tcpiphdr);
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if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN)
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panic("tcp_init");
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}
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/*
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* Create template to be used to send tcp packets on a connection.
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* Call after host entry created, allocates an mbuf and fills
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* in a skeletal tcp/ip header, minimizing the amount of work
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* necessary when the connection is used.
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*/
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struct tcpiphdr *
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tcp_template(tp)
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struct tcpcb *tp;
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{
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register struct inpcb *inp = tp->t_inpcb;
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register struct mbuf *m;
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register struct tcpiphdr *n;
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if ((n = tp->t_template) == 0) {
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m = m_get(M_DONTWAIT, MT_HEADER);
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if (m == NULL)
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return (0);
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m->m_len = sizeof (struct tcpiphdr);
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n = mtod(m, struct tcpiphdr *);
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}
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bzero(n->ti_x1, sizeof(n->ti_x1));
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n->ti_pr = IPPROTO_TCP;
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n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
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n->ti_src = inp->inp_laddr;
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n->ti_dst = inp->inp_faddr;
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n->ti_sport = inp->inp_lport;
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n->ti_dport = inp->inp_fport;
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n->ti_seq = 0;
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n->ti_ack = 0;
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n->ti_x2 = 0;
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n->ti_off = 5;
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n->ti_flags = 0;
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n->ti_win = 0;
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n->ti_sum = 0;
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n->ti_urp = 0;
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return (n);
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}
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/*
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* Send a single message to the TCP at address specified by
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* the given TCP/IP header. If m == 0, then we make a copy
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* of the tcpiphdr at ti and send directly to the addressed host.
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* This is used to force keep alive messages out using the TCP
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* template for a connection tp->t_template. If flags are given
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* then we send a message back to the TCP which originated the
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* segment ti, and discard the mbuf containing it and any other
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* attached mbufs.
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*
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* In any case the ack and sequence number of the transmitted
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* segment are as specified by the parameters.
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*
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* NOTE: If m != NULL, then ti must point to *inside* the mbuf.
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*/
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void
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tcp_respond(tp, ti, m, ack, seq, flags)
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struct tcpcb *tp;
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register struct tcpiphdr *ti;
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register struct mbuf *m;
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tcp_seq ack, seq;
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int flags;
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{
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register int tlen;
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int win = 0;
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struct route *ro = 0;
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struct route sro;
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if (tp) {
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if (!(flags & TH_RST))
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win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
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ro = &tp->t_inpcb->inp_route;
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} else {
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ro = &sro;
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bzero(ro, sizeof *ro);
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}
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if (m == 0) {
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m = m_gethdr(M_DONTWAIT, MT_HEADER);
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if (m == NULL)
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return;
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#ifdef TCP_COMPAT_42
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tlen = 1;
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#else
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tlen = 0;
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#endif
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m->m_data += max_linkhdr;
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*mtod(m, struct tcpiphdr *) = *ti;
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ti = mtod(m, struct tcpiphdr *);
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flags = TH_ACK;
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} else {
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m_freem(m->m_next);
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m->m_next = 0;
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m->m_data = (caddr_t)ti;
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m->m_len = sizeof (struct tcpiphdr);
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tlen = 0;
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#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
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xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, n_long);
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xchg(ti->ti_dport, ti->ti_sport, n_short);
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#undef xchg
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}
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ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
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tlen += sizeof (struct tcpiphdr);
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m->m_len = tlen;
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m->m_pkthdr.len = tlen;
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m->m_pkthdr.rcvif = (struct ifnet *) 0;
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bzero(ti->ti_x1, sizeof(ti->ti_x1));
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ti->ti_seq = htonl(seq);
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ti->ti_ack = htonl(ack);
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ti->ti_x2 = 0;
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ti->ti_off = sizeof (struct tcphdr) >> 2;
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ti->ti_flags = flags;
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if (tp)
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ti->ti_win = htons((u_short) (win >> tp->rcv_scale));
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else
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ti->ti_win = htons((u_short)win);
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ti->ti_urp = 0;
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ti->ti_sum = 0;
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ti->ti_sum = in_cksum(m, tlen);
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((struct ip *)ti)->ip_len = tlen;
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((struct ip *)ti)->ip_ttl = ip_defttl;
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#ifdef TCPDEBUG
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if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
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tcp_trace(TA_OUTPUT, 0, tp, ti, 0);
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#endif
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(void) ip_output(m, NULL, ro, 0, NULL);
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if (ro == &sro && ro->ro_rt) {
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RTFREE(ro->ro_rt);
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}
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}
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/*
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* Create a new TCP control block, making an
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* empty reassembly queue and hooking it to the argument
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* protocol control block. The `inp' parameter must have
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* come from the zone allocator set up in tcp_init().
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*/
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struct tcpcb *
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tcp_newtcpcb(inp)
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struct inpcb *inp;
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{
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struct inp_tp *it;
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register struct tcpcb *tp;
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it = (struct inp_tp *)inp;
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tp = &it->tcb;
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bzero((char *) tp, sizeof(struct tcpcb));
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tp->t_segq = NULL;
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tp->t_maxseg = tp->t_maxopd = tcp_mssdflt;
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if (tcp_do_rfc1323)
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tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
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if (tcp_do_rfc1644)
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tp->t_flags |= TF_REQ_CC;
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tp->t_inpcb = inp; /* XXX */
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/*
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* Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
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* rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
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* reasonable initial retransmit time.
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*/
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tp->t_srtt = TCPTV_SRTTBASE;
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tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
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tp->t_rttmin = TCPTV_MIN;
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tp->t_rxtcur = TCPTV_RTOBASE;
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tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
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tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
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inp->inp_ip_ttl = ip_defttl;
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inp->inp_ppcb = (caddr_t)tp;
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return (tp); /* XXX */
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}
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/*
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* Drop a TCP connection, reporting
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* the specified error. If connection is synchronized,
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* then send a RST to peer.
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*/
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struct tcpcb *
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tcp_drop(tp, errno)
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register struct tcpcb *tp;
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int errno;
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{
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struct socket *so = tp->t_inpcb->inp_socket;
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if (TCPS_HAVERCVDSYN(tp->t_state)) {
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tp->t_state = TCPS_CLOSED;
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(void) tcp_output(tp);
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tcpstat.tcps_drops++;
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} else
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tcpstat.tcps_conndrops++;
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if (errno == ETIMEDOUT && tp->t_softerror)
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errno = tp->t_softerror;
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so->so_error = errno;
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return (tcp_close(tp));
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}
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/*
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* Close a TCP control block:
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* discard all space held by the tcp
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* discard internet protocol block
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* wake up any sleepers
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*/
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struct tcpcb *
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tcp_close(tp)
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register struct tcpcb *tp;
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{
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register struct mbuf *q;
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register struct mbuf *nq;
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struct inpcb *inp = tp->t_inpcb;
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struct socket *so = inp->inp_socket;
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register struct rtentry *rt;
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int dosavessthresh;
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/*
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* If we got enough samples through the srtt filter,
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* save the rtt and rttvar in the routing entry.
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* 'Enough' is arbitrarily defined as the 16 samples.
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* 16 samples is enough for the srtt filter to converge
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* to within 5% of the correct value; fewer samples and
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* we could save a very bogus rtt.
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*
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* Don't update the default route's characteristics and don't
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* update anything that the user "locked".
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*/
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if (tp->t_rttupdated >= 16 &&
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(rt = inp->inp_route.ro_rt) &&
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((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) {
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register u_long i = 0;
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if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
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i = tp->t_srtt *
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(RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE));
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if (rt->rt_rmx.rmx_rtt && i)
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/*
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* filter this update to half the old & half
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* the new values, converting scale.
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* See route.h and tcp_var.h for a
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* description of the scaling constants.
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*/
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rt->rt_rmx.rmx_rtt =
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(rt->rt_rmx.rmx_rtt + i) / 2;
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else
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rt->rt_rmx.rmx_rtt = i;
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tcpstat.tcps_cachedrtt++;
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}
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if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
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i = tp->t_rttvar *
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(RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE));
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if (rt->rt_rmx.rmx_rttvar && i)
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rt->rt_rmx.rmx_rttvar =
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(rt->rt_rmx.rmx_rttvar + i) / 2;
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else
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rt->rt_rmx.rmx_rttvar = i;
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tcpstat.tcps_cachedrttvar++;
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}
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/*
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* The old comment here said:
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* update the pipelimit (ssthresh) if it has been updated
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* already or if a pipesize was specified & the threshhold
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* got below half the pipesize. I.e., wait for bad news
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* before we start updating, then update on both good
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* and bad news.
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*
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* But we want to save the ssthresh even if no pipesize is
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* specified explicitly in the route, because such
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* connections still have an implicit pipesize specified
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* by the global tcp_sendspace. In the absence of a reliable
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* way to calculate the pipesize, it will have to do.
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*/
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i = tp->snd_ssthresh;
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if (rt->rt_rmx.rmx_sendpipe != 0)
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dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2);
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else
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dosavessthresh = (i < so->so_snd.sb_hiwat / 2);
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if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 &&
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i != 0 && rt->rt_rmx.rmx_ssthresh != 0)
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|| dosavessthresh) {
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/*
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* convert the limit from user data bytes to
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* packets then to packet data bytes.
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*/
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i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
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if (i < 2)
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i = 2;
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i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr));
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if (rt->rt_rmx.rmx_ssthresh)
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rt->rt_rmx.rmx_ssthresh =
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(rt->rt_rmx.rmx_ssthresh + i) / 2;
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else
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rt->rt_rmx.rmx_ssthresh = i;
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tcpstat.tcps_cachedssthresh++;
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}
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}
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/* free the reassembly queue, if any */
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for (q = tp->t_segq; q; q = nq) {
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nq = q->m_nextpkt;
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tp->t_segq = nq;
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m_freem(q);
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}
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if (tp->t_template)
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(void) m_free(dtom(tp->t_template));
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inp->inp_ppcb = NULL;
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soisdisconnected(so);
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in_pcbdetach(inp);
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tcpstat.tcps_closed++;
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return ((struct tcpcb *)0);
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}
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void
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tcp_drain()
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{
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}
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/*
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* Notify a tcp user of an asynchronous error;
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* store error as soft error, but wake up user
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* (for now, won't do anything until can select for soft error).
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*/
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static void
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tcp_notify(inp, error)
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struct inpcb *inp;
|
|
int error;
|
|
{
|
|
register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb;
|
|
register struct socket *so = inp->inp_socket;
|
|
|
|
/*
|
|
* Ignore some errors if we are hooked up.
|
|
* If connection hasn't completed, has retransmitted several times,
|
|
* and receives a second error, give up now. This is better
|
|
* than waiting a long time to establish a connection that
|
|
* can never complete.
|
|
*/
|
|
if (tp->t_state == TCPS_ESTABLISHED &&
|
|
(error == EHOSTUNREACH || error == ENETUNREACH ||
|
|
error == EHOSTDOWN)) {
|
|
return;
|
|
} else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
|
|
tp->t_softerror)
|
|
so->so_error = error;
|
|
else
|
|
tp->t_softerror = error;
|
|
wakeup((caddr_t) &so->so_timeo);
|
|
sorwakeup(so);
|
|
sowwakeup(so);
|
|
}
|
|
|
|
static int
|
|
tcp_pcblist SYSCTL_HANDLER_ARGS
|
|
{
|
|
int error, i, n, s;
|
|
struct inpcb *inp, **inp_list;
|
|
inp_gen_t gencnt;
|
|
struct xinpgen xig;
|
|
|
|
/*
|
|
* The process of preparing the TCB list is too time-consuming and
|
|
* resource-intensive to repeat twice on every request.
|
|
*/
|
|
if (req->oldptr == 0) {
|
|
n = tcbinfo.ipi_count;
|
|
req->oldidx = 2 * (sizeof xig)
|
|
+ (n + n/8) * sizeof(struct xtcpcb);
|
|
return 0;
|
|
}
|
|
|
|
if (req->newptr != 0)
|
|
return EPERM;
|
|
|
|
/*
|
|
* OK, now we're committed to doing something.
|
|
*/
|
|
s = splnet();
|
|
gencnt = tcbinfo.ipi_gencnt;
|
|
n = tcbinfo.ipi_count;
|
|
splx(s);
|
|
|
|
xig.xig_len = sizeof xig;
|
|
xig.xig_count = n;
|
|
xig.xig_gen = gencnt;
|
|
xig.xig_sogen = so_gencnt;
|
|
error = SYSCTL_OUT(req, &xig, sizeof xig);
|
|
if (error)
|
|
return error;
|
|
|
|
inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
|
|
if (inp_list == 0)
|
|
return ENOMEM;
|
|
|
|
s = splnet();
|
|
for (inp = tcbinfo.listhead->lh_first, i = 0; inp && i < n;
|
|
inp = inp->inp_list.le_next) {
|
|
if (inp->inp_gencnt <= gencnt)
|
|
inp_list[i++] = inp;
|
|
}
|
|
splx(s);
|
|
n = i;
|
|
|
|
error = 0;
|
|
for (i = 0; i < n; i++) {
|
|
inp = inp_list[i];
|
|
if (inp->inp_gencnt <= gencnt) {
|
|
struct xtcpcb xt;
|
|
xt.xt_len = sizeof xt;
|
|
/* XXX should avoid extra copy */
|
|
bcopy(inp, &xt.xt_inp, sizeof *inp);
|
|
bcopy(inp->inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
|
|
if (inp->inp_socket)
|
|
sotoxsocket(inp->inp_socket, &xt.xt_socket);
|
|
error = SYSCTL_OUT(req, &xt, sizeof xt);
|
|
}
|
|
}
|
|
if (!error) {
|
|
/*
|
|
* Give the user an updated idea of our state.
|
|
* If the generation differs from what we told
|
|
* her before, she knows that something happened
|
|
* while we were processing this request, and it
|
|
* might be necessary to retry.
|
|
*/
|
|
s = splnet();
|
|
xig.xig_gen = tcbinfo.ipi_gencnt;
|
|
xig.xig_sogen = so_gencnt;
|
|
xig.xig_count = tcbinfo.ipi_count;
|
|
splx(s);
|
|
error = SYSCTL_OUT(req, &xig, sizeof xig);
|
|
}
|
|
free(inp_list, M_TEMP);
|
|
return error;
|
|
}
|
|
|
|
SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
|
|
tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
|
|
|
|
void
|
|
tcp_ctlinput(cmd, sa, vip)
|
|
int cmd;
|
|
struct sockaddr *sa;
|
|
void *vip;
|
|
{
|
|
register struct ip *ip = vip;
|
|
register struct tcphdr *th;
|
|
void (*notify) __P((struct inpcb *, int)) = tcp_notify;
|
|
|
|
if (cmd == PRC_QUENCH)
|
|
notify = tcp_quench;
|
|
else if (cmd == PRC_MSGSIZE)
|
|
notify = tcp_mtudisc;
|
|
else if (!PRC_IS_REDIRECT(cmd) &&
|
|
((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0))
|
|
return;
|
|
if (ip) {
|
|
th = (struct tcphdr *)((caddr_t)ip
|
|
+ (IP_VHL_HL(ip->ip_vhl) << 2));
|
|
in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport,
|
|
cmd, notify);
|
|
} else
|
|
in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify);
|
|
}
|
|
|
|
/*
|
|
* When a source quench is received, close congestion window
|
|
* to one segment. We will gradually open it again as we proceed.
|
|
*/
|
|
void
|
|
tcp_quench(inp, errno)
|
|
struct inpcb *inp;
|
|
int errno;
|
|
{
|
|
struct tcpcb *tp = intotcpcb(inp);
|
|
|
|
if (tp)
|
|
tp->snd_cwnd = tp->t_maxseg;
|
|
}
|
|
|
|
/*
|
|
* When `need fragmentation' ICMP is received, update our idea of the MSS
|
|
* based on the new value in the route. Also nudge TCP to send something,
|
|
* since we know the packet we just sent was dropped.
|
|
* This duplicates some code in the tcp_mss() function in tcp_input.c.
|
|
*/
|
|
void
|
|
tcp_mtudisc(inp, errno)
|
|
struct inpcb *inp;
|
|
int errno;
|
|
{
|
|
struct tcpcb *tp = intotcpcb(inp);
|
|
struct rtentry *rt;
|
|
struct rmxp_tao *taop;
|
|
struct socket *so = inp->inp_socket;
|
|
int offered;
|
|
int mss;
|
|
|
|
if (tp) {
|
|
rt = tcp_rtlookup(inp);
|
|
if (!rt || !rt->rt_rmx.rmx_mtu) {
|
|
tp->t_maxopd = tp->t_maxseg = tcp_mssdflt;
|
|
return;
|
|
}
|
|
taop = rmx_taop(rt->rt_rmx);
|
|
offered = taop->tao_mssopt;
|
|
mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr);
|
|
if (offered)
|
|
mss = min(mss, offered);
|
|
/*
|
|
* XXX - The above conditional 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.
|
|
*/
|
|
if (tp->t_maxopd <= mss)
|
|
return;
|
|
tp->t_maxopd = mss;
|
|
|
|
if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
|
|
(tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)
|
|
mss -= TCPOLEN_TSTAMP_APPA;
|
|
if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC &&
|
|
(tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)
|
|
mss -= TCPOLEN_CC_APPA;
|
|
#if (MCLBYTES & (MCLBYTES - 1)) == 0
|
|
if (mss > MCLBYTES)
|
|
mss &= ~(MCLBYTES-1);
|
|
#else
|
|
if (mss > MCLBYTES)
|
|
mss = mss / MCLBYTES * MCLBYTES;
|
|
#endif
|
|
if (so->so_snd.sb_hiwat < mss)
|
|
mss = so->so_snd.sb_hiwat;
|
|
|
|
tp->t_maxseg = mss;
|
|
|
|
tcpstat.tcps_mturesent++;
|
|
tp->t_rtt = 0;
|
|
tp->snd_nxt = tp->snd_una;
|
|
tcp_output(tp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Look-up the routing entry to the peer of this inpcb. If no route
|
|
* is found and it cannot be allocated the return NULL. This routine
|
|
* is called by TCP routines that access the rmx structure and by tcp_mss
|
|
* to get the interface MTU.
|
|
*/
|
|
struct rtentry *
|
|
tcp_rtlookup(inp)
|
|
struct inpcb *inp;
|
|
{
|
|
struct route *ro;
|
|
struct rtentry *rt;
|
|
|
|
ro = &inp->inp_route;
|
|
rt = ro->ro_rt;
|
|
if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
|
|
/* No route yet, so try to acquire one */
|
|
if (inp->inp_faddr.s_addr != INADDR_ANY) {
|
|
ro->ro_dst.sa_family = AF_INET;
|
|
ro->ro_dst.sa_len = sizeof(ro->ro_dst);
|
|
((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
|
|
inp->inp_faddr;
|
|
rtalloc(ro);
|
|
rt = ro->ro_rt;
|
|
}
|
|
}
|
|
return rt;
|
|
}
|
|
|
|
/*
|
|
* Return a pointer to the cached information about the remote host.
|
|
* The cached information is stored in the protocol specific part of
|
|
* the route metrics.
|
|
*/
|
|
struct rmxp_tao *
|
|
tcp_gettaocache(inp)
|
|
struct inpcb *inp;
|
|
{
|
|
struct rtentry *rt = tcp_rtlookup(inp);
|
|
|
|
/* Make sure this is a host route and is up. */
|
|
if (rt == NULL ||
|
|
(rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
|
|
return NULL;
|
|
|
|
return rmx_taop(rt->rt_rmx);
|
|
}
|
|
|
|
/*
|
|
* Clear all the TAO cache entries, called from tcp_init.
|
|
*
|
|
* XXX
|
|
* This routine is just an empty one, because we assume that the routing
|
|
* routing tables are initialized at the same time when TCP, so there is
|
|
* nothing in the cache left over.
|
|
*/
|
|
static void
|
|
tcp_cleartaocache()
|
|
{
|
|
}
|