201d185b69
recwin and sendwin. This removes a big source of confusion and makes following the code much easier. Reviewed by: sam (mentor) Obtained from: DragonFlyBSD rev 1.6 (hsu)
1000 lines
28 KiB
C
1000 lines
28 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_output.c 8.4 (Berkeley) 5/24/95
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* $FreeBSD$
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*/
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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/systm.h>
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#include <sys/domain.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mac.h>
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#include <sys/mbuf.h>
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#include <sys/mutex.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#ifdef INET6
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#include <netinet6/in6_pcb.h>
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#include <netinet/ip6.h>
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#include <netinet6/ip6_var.h>
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#endif
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#include <netinet/tcp.h>
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#define TCPOUTFLAGS
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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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#ifdef IPSEC
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#include <netinet6/ipsec.h>
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#endif /*IPSEC*/
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#ifdef FAST_IPSEC
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#include <netipsec/ipsec.h>
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#define IPSEC
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#endif /*FAST_IPSEC*/
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#include <machine/in_cksum.h>
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#ifdef notyet
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extern struct mbuf *m_copypack();
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#endif
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int path_mtu_discovery = 1;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_RW,
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&path_mtu_discovery, 1, "Enable Path MTU Discovery");
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int ss_fltsz = 1;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, slowstart_flightsize, CTLFLAG_RW,
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&ss_fltsz, 1, "Slow start flight size");
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int ss_fltsz_local = 4;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, local_slowstart_flightsize, CTLFLAG_RW,
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&ss_fltsz_local, 1, "Slow start flight size for local networks");
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int tcp_do_newreno = 1;
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SYSCTL_INT(_net_inet_tcp, OID_AUTO, newreno, CTLFLAG_RW, &tcp_do_newreno,
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0, "Enable NewReno Algorithms");
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/*
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* Tcp output routine: figure out what should be sent and send it.
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*/
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int
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tcp_output(struct tcpcb *tp)
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{
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struct socket *so = tp->t_inpcb->inp_socket;
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long len, recwin, sendwin;
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int off, flags, error;
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struct mbuf *m;
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struct ip *ip = NULL;
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struct ipovly *ipov = NULL;
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struct tcphdr *th;
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u_char opt[TCP_MAXOLEN];
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unsigned ipoptlen, optlen, hdrlen;
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int idle, sendalot;
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#if 0
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int maxburst = TCP_MAXBURST;
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#endif
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struct rmxp_tao tao;
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#ifdef INET6
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struct ip6_hdr *ip6 = NULL;
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int isipv6;
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bzero(&tao, sizeof(tao));
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isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
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#endif
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INP_LOCK_ASSERT(tp->t_inpcb);
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/*
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* Determine length of data that should be transmitted,
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* and flags that will be used.
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* If there is some data or critical controls (SYN, RST)
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* to send, then transmit; otherwise, investigate further.
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*/
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idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una);
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if (idle && (ticks - tp->t_rcvtime) >= tp->t_rxtcur) {
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/*
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* We have been idle for "a while" and no acks are
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* expected to clock out any data we send --
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* slow start to get ack "clock" running again.
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*
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* Set the slow-start flight size depending on whether
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* this is a local network or not.
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*/
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int ss = ss_fltsz;
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#ifdef INET6
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if (isipv6) {
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if (in6_localaddr(&tp->t_inpcb->in6p_faddr))
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ss = ss_fltsz_local;
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} else
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#endif /* INET6 */
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if (in_localaddr(tp->t_inpcb->inp_faddr))
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ss = ss_fltsz_local;
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tp->snd_cwnd = tp->t_maxseg * ss;
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}
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tp->t_flags &= ~TF_LASTIDLE;
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if (idle) {
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if (tp->t_flags & TF_MORETOCOME) {
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tp->t_flags |= TF_LASTIDLE;
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idle = 0;
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}
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}
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again:
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sendalot = 0;
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off = tp->snd_nxt - tp->snd_una;
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sendwin = min(tp->snd_wnd, tp->snd_cwnd);
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sendwin = min(sendwin, tp->snd_bwnd);
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flags = tcp_outflags[tp->t_state];
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/*
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* Get standard flags, and add SYN or FIN if requested by 'hidden'
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* state flags.
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*/
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if (tp->t_flags & TF_NEEDFIN)
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flags |= TH_FIN;
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if (tp->t_flags & TF_NEEDSYN)
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flags |= TH_SYN;
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/*
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* If in persist timeout with window of 0, send 1 byte.
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* Otherwise, if window is small but nonzero
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* and timer expired, we will send what we can
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* and go to transmit state.
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*/
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if (tp->t_force) {
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if (sendwin == 0) {
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/*
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* If we still have some data to send, then
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* clear the FIN bit. Usually this would
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* happen below when it realizes that we
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* aren't sending all the data. However,
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* if we have exactly 1 byte of unsent data,
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* then it won't clear the FIN bit below,
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* and if we are in persist state, we wind
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* up sending the packet without recording
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* that we sent the FIN bit.
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*
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* We can't just blindly clear the FIN bit,
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* because if we don't have any more data
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* to send then the probe will be the FIN
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* itself.
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*/
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if (off < so->so_snd.sb_cc)
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flags &= ~TH_FIN;
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sendwin = 1;
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} else {
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callout_stop(tp->tt_persist);
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tp->t_rxtshift = 0;
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}
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}
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/*
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* If snd_nxt == snd_max and we have transmitted a FIN, the
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* offset will be > 0 even if so_snd.sb_cc is 0, resulting in
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* a negative length. This can also occur when TCP opens up
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* its congestion window while receiving additional duplicate
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* acks after fast-retransmit because TCP will reset snd_nxt
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* to snd_max after the fast-retransmit.
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*
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* In the normal retransmit-FIN-only case, however, snd_nxt will
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* be set to snd_una, the offset will be 0, and the length may
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* wind up 0.
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*/
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len = (long)ulmin(so->so_snd.sb_cc, sendwin) - off;
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/*
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* Lop off SYN bit if it has already been sent. However, if this
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* is SYN-SENT state and if segment contains data and if we don't
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* know that foreign host supports TAO, suppress sending segment.
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*/
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if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una)) {
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flags &= ~TH_SYN;
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off--, len++;
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if (tcp_do_rfc1644)
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tcp_hc_gettao(&tp->t_inpcb->inp_inc, &tao);
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if (len > 0 && tp->t_state == TCPS_SYN_SENT &&
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tao.tao_ccsent == 0)
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return 0;
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}
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/*
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* Be careful not to send data and/or FIN on SYN segments
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* in cases when no CC option will be sent.
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* This measure is needed to prevent interoperability problems
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* with not fully conformant TCP implementations.
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*/
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if ((flags & TH_SYN) &&
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((tp->t_flags & TF_NOOPT) || !(tp->t_flags & TF_REQ_CC) ||
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((flags & TH_ACK) && !(tp->t_flags & TF_RCVD_CC)))) {
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len = 0;
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flags &= ~TH_FIN;
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}
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if (len < 0) {
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/*
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* If FIN has been sent but not acked,
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* but we haven't been called to retransmit,
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* len will be < 0. Otherwise, window shrank
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* after we sent into it. If window shrank to 0,
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* cancel pending retransmit, pull snd_nxt back
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* to (closed) window, and set the persist timer
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* if it isn't already going. If the window didn't
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* close completely, just wait for an ACK.
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*/
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len = 0;
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if (sendwin == 0) {
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callout_stop(tp->tt_rexmt);
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tp->t_rxtshift = 0;
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tp->snd_nxt = tp->snd_una;
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if (!callout_active(tp->tt_persist))
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tcp_setpersist(tp);
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}
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}
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/*
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* len will be >= 0 after this point. Truncate to the maximum
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* segment length and ensure that FIN is removed if the length
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* no longer contains the last data byte.
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*/
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if (len > tp->t_maxseg) {
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len = tp->t_maxseg;
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sendalot = 1;
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}
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if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc))
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flags &= ~TH_FIN;
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recwin = sbspace(&so->so_rcv);
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/*
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* Sender silly window avoidance. We transmit under the following
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* conditions when len is non-zero:
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*
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* - We have a full segment
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* - This is the last buffer in a write()/send() and we are
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* either idle or running NODELAY
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* - we've timed out (e.g. persist timer)
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* - we have more then 1/2 the maximum send window's worth of
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* data (receiver may be limited the window size)
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* - we need to retransmit
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*/
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if (len) {
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if (len == tp->t_maxseg)
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goto send;
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/*
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* NOTE! on localhost connections an 'ack' from the remote
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* end may occur synchronously with the output and cause
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* us to flush a buffer queued with moretocome. XXX
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*
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* note: the len + off check is almost certainly unnecessary.
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*/
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if (!(tp->t_flags & TF_MORETOCOME) && /* normal case */
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(idle || (tp->t_flags & TF_NODELAY)) &&
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len + off >= so->so_snd.sb_cc &&
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(tp->t_flags & TF_NOPUSH) == 0) {
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goto send;
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}
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if (tp->t_force) /* typ. timeout case */
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goto send;
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if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
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goto send;
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if (SEQ_LT(tp->snd_nxt, tp->snd_max)) /* retransmit case */
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goto send;
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}
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/*
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* Compare available window to amount of window
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* known to peer (as advertised window less
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* next expected input). If the difference is at least two
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* max size segments, or at least 50% of the maximum possible
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* window, then want to send a window update to peer.
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* Skip this if the connection is in T/TCP half-open state.
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*/
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if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN)) {
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/*
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* "adv" is the amount we can increase the window,
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* taking into account that we are limited by
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* TCP_MAXWIN << tp->rcv_scale.
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*/
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long adv = min(recwin, (long)TCP_MAXWIN << tp->rcv_scale) -
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(tp->rcv_adv - tp->rcv_nxt);
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if (adv >= (long) (2 * tp->t_maxseg))
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goto send;
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if (2 * adv >= (long) so->so_rcv.sb_hiwat)
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goto send;
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}
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/*
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* Send if we owe the peer an ACK, RST, SYN, or urgent data. ACKNOW
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* is also a catch-all for the retransmit timer timeout case.
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*/
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if (tp->t_flags & TF_ACKNOW)
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goto send;
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if ((flags & TH_RST) ||
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((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0))
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goto send;
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if (SEQ_GT(tp->snd_up, tp->snd_una))
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goto send;
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/*
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* If our state indicates that FIN should be sent
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* and we have not yet done so, then we need to send.
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*/
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if (flags & TH_FIN &&
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((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una))
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goto send;
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/*
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* TCP window updates are not reliable, rather a polling protocol
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* using ``persist'' packets is used to insure receipt of window
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* updates. The three ``states'' for the output side are:
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* idle not doing retransmits or persists
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* persisting to move a small or zero window
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* (re)transmitting and thereby not persisting
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*
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* callout_active(tp->tt_persist)
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* is true when we are in persist state.
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* tp->t_force
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* is set when we are called to send a persist packet.
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* callout_active(tp->tt_rexmt)
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* is set when we are retransmitting
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* The output side is idle when both timers are zero.
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*
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* If send window is too small, there is data to transmit, and no
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* retransmit or persist is pending, then go to persist state.
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* If nothing happens soon, send when timer expires:
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* if window is nonzero, transmit what we can,
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* otherwise force out a byte.
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*/
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if (so->so_snd.sb_cc && !callout_active(tp->tt_rexmt) &&
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!callout_active(tp->tt_persist)) {
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tp->t_rxtshift = 0;
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tcp_setpersist(tp);
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}
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/*
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* No reason to send a segment, just return.
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*/
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return (0);
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send:
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/*
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* Before ESTABLISHED, force sending of initial options
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* unless TCP set not to do any options.
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* NOTE: we assume that the IP/TCP header plus TCP options
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* always fit in a single mbuf, leaving room for a maximum
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* link header, i.e.
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* max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES
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*/
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optlen = 0;
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#ifdef INET6
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if (isipv6)
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hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
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else
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#endif
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hdrlen = sizeof (struct tcpiphdr);
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if (flags & TH_SYN) {
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tp->snd_nxt = tp->iss;
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if ((tp->t_flags & TF_NOOPT) == 0) {
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u_short mss;
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opt[0] = TCPOPT_MAXSEG;
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opt[1] = TCPOLEN_MAXSEG;
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mss = htons((u_short) tcp_mssopt(&tp->t_inpcb->inp_inc));
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(void)memcpy(opt + 2, &mss, sizeof(mss));
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optlen = TCPOLEN_MAXSEG;
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if ((tp->t_flags & TF_REQ_SCALE) &&
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((flags & TH_ACK) == 0 ||
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(tp->t_flags & TF_RCVD_SCALE))) {
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*((u_int32_t *)(opt + optlen)) = htonl(
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TCPOPT_NOP << 24 |
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TCPOPT_WINDOW << 16 |
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TCPOLEN_WINDOW << 8 |
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tp->request_r_scale);
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optlen += 4;
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}
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}
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}
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/*
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* Send a timestamp and echo-reply if this is a SYN and our side
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* wants to use timestamps (TF_REQ_TSTMP is set) or both our side
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* and our peer have sent timestamps in our SYN's.
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*/
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if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
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(flags & TH_RST) == 0 &&
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((flags & TH_ACK) == 0 ||
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(tp->t_flags & TF_RCVD_TSTMP))) {
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u_int32_t *lp = (u_int32_t *)(opt + optlen);
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/* Form timestamp option as shown in appendix A of RFC 1323. */
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*lp++ = htonl(TCPOPT_TSTAMP_HDR);
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*lp++ = htonl(ticks);
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*lp = htonl(tp->ts_recent);
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optlen += TCPOLEN_TSTAMP_APPA;
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}
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/*
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* Send `CC-family' options if our side wants to use them (TF_REQ_CC),
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* options are allowed (!TF_NOOPT) and it's not a RST.
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*/
|
|
if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC &&
|
|
(flags & TH_RST) == 0) {
|
|
switch (flags & (TH_SYN|TH_ACK)) {
|
|
/*
|
|
* This is a normal ACK, send CC if we received CC before
|
|
* from our peer.
|
|
*/
|
|
case TH_ACK:
|
|
if (!(tp->t_flags & TF_RCVD_CC))
|
|
break;
|
|
/*FALLTHROUGH*/
|
|
|
|
/*
|
|
* We can only get here in T/TCP's SYN_SENT* state, when
|
|
* we're a sending a non-SYN segment without waiting for
|
|
* the ACK of our SYN. A check above assures that we only
|
|
* do this if our peer understands T/TCP.
|
|
*/
|
|
case 0:
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_CC;
|
|
opt[optlen++] = TCPOLEN_CC;
|
|
*(u_int32_t *)&opt[optlen] = htonl(tp->cc_send);
|
|
|
|
optlen += 4;
|
|
break;
|
|
|
|
/*
|
|
* This is our initial SYN, check whether we have to use
|
|
* CC or CC.new.
|
|
*/
|
|
case TH_SYN:
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = tp->t_flags & TF_SENDCCNEW ?
|
|
TCPOPT_CCNEW : TCPOPT_CC;
|
|
opt[optlen++] = TCPOLEN_CC;
|
|
*(u_int32_t *)&opt[optlen] = htonl(tp->cc_send);
|
|
optlen += 4;
|
|
break;
|
|
|
|
/*
|
|
* This is a SYN,ACK; send CC and CC.echo if we received
|
|
* CC from our peer.
|
|
*/
|
|
case (TH_SYN|TH_ACK):
|
|
if (tp->t_flags & TF_RCVD_CC) {
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_CC;
|
|
opt[optlen++] = TCPOLEN_CC;
|
|
*(u_int32_t *)&opt[optlen] =
|
|
htonl(tp->cc_send);
|
|
optlen += 4;
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_NOP;
|
|
opt[optlen++] = TCPOPT_CCECHO;
|
|
opt[optlen++] = TCPOLEN_CC;
|
|
*(u_int32_t *)&opt[optlen] =
|
|
htonl(tp->cc_recv);
|
|
optlen += 4;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
hdrlen += optlen;
|
|
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
ipoptlen = ip6_optlen(tp->t_inpcb);
|
|
else
|
|
#endif
|
|
if (tp->t_inpcb->inp_options)
|
|
ipoptlen = tp->t_inpcb->inp_options->m_len -
|
|
offsetof(struct ipoption, ipopt_list);
|
|
else
|
|
ipoptlen = 0;
|
|
#ifdef IPSEC
|
|
ipoptlen += ipsec_hdrsiz_tcp(tp);
|
|
#endif
|
|
|
|
/*
|
|
* Adjust data length if insertion of options will
|
|
* bump the packet length beyond the t_maxopd length.
|
|
* Clear the FIN bit because we cut off the tail of
|
|
* the segment.
|
|
*/
|
|
if (len + optlen + ipoptlen > tp->t_maxopd) {
|
|
/*
|
|
* If there is still more to send, don't close the connection.
|
|
*/
|
|
flags &= ~TH_FIN;
|
|
len = tp->t_maxopd - optlen - ipoptlen;
|
|
sendalot = 1;
|
|
}
|
|
|
|
/*#ifdef DIAGNOSTIC*/
|
|
#ifdef INET6
|
|
if (max_linkhdr + hdrlen > MCLBYTES)
|
|
#else
|
|
if (max_linkhdr + hdrlen > MHLEN)
|
|
#endif
|
|
panic("tcphdr too big");
|
|
/*#endif*/
|
|
|
|
/*
|
|
* Grab a header mbuf, attaching a copy of data to
|
|
* be transmitted, and initialize the header from
|
|
* the template for sends on this connection.
|
|
*/
|
|
if (len) {
|
|
if (tp->t_force && len == 1)
|
|
tcpstat.tcps_sndprobe++;
|
|
else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) {
|
|
tcpstat.tcps_sndrexmitpack++;
|
|
tcpstat.tcps_sndrexmitbyte += len;
|
|
} else {
|
|
tcpstat.tcps_sndpack++;
|
|
tcpstat.tcps_sndbyte += len;
|
|
}
|
|
#ifdef notyet
|
|
if ((m = m_copypack(so->so_snd.sb_mb, off,
|
|
(int)len, max_linkhdr + hdrlen)) == 0) {
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
/*
|
|
* m_copypack left space for our hdr; use it.
|
|
*/
|
|
m->m_len += hdrlen;
|
|
m->m_data -= hdrlen;
|
|
#else
|
|
MGETHDR(m, M_DONTWAIT, MT_HEADER);
|
|
if (m == NULL) {
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
#ifdef INET6
|
|
if (MHLEN < hdrlen + max_linkhdr) {
|
|
MCLGET(m, M_DONTWAIT);
|
|
if ((m->m_flags & M_EXT) == 0) {
|
|
m_freem(m);
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
}
|
|
#endif
|
|
m->m_data += max_linkhdr;
|
|
m->m_len = hdrlen;
|
|
if (len <= MHLEN - hdrlen - max_linkhdr) {
|
|
m_copydata(so->so_snd.sb_mb, off, (int) len,
|
|
mtod(m, caddr_t) + hdrlen);
|
|
m->m_len += len;
|
|
} else {
|
|
m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
|
|
if (m->m_next == 0) {
|
|
(void) m_free(m);
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
}
|
|
#endif
|
|
/*
|
|
* If we're sending everything we've got, set PUSH.
|
|
* (This will keep happy those implementations which only
|
|
* give data to the user when a buffer fills or
|
|
* a PUSH comes in.)
|
|
*/
|
|
if (off + len == so->so_snd.sb_cc)
|
|
flags |= TH_PUSH;
|
|
} else {
|
|
if (tp->t_flags & TF_ACKNOW)
|
|
tcpstat.tcps_sndacks++;
|
|
else if (flags & (TH_SYN|TH_FIN|TH_RST))
|
|
tcpstat.tcps_sndctrl++;
|
|
else if (SEQ_GT(tp->snd_up, tp->snd_una))
|
|
tcpstat.tcps_sndurg++;
|
|
else
|
|
tcpstat.tcps_sndwinup++;
|
|
|
|
MGETHDR(m, M_DONTWAIT, MT_HEADER);
|
|
if (m == NULL) {
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
#ifdef INET6
|
|
if (isipv6 && (MHLEN < hdrlen + max_linkhdr) &&
|
|
MHLEN >= hdrlen) {
|
|
MH_ALIGN(m, hdrlen);
|
|
} else
|
|
#endif
|
|
m->m_data += max_linkhdr;
|
|
m->m_len = hdrlen;
|
|
}
|
|
m->m_pkthdr.rcvif = (struct ifnet *)0;
|
|
#ifdef MAC
|
|
mac_create_mbuf_from_socket(so, m);
|
|
#endif
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
th = (struct tcphdr *)(ip6 + 1);
|
|
tcpip_fillheaders(tp->t_inpcb, ip6, th);
|
|
} else
|
|
#endif /* INET6 */
|
|
{
|
|
ip = mtod(m, struct ip *);
|
|
ipov = (struct ipovly *)ip;
|
|
th = (struct tcphdr *)(ip + 1);
|
|
tcpip_fillheaders(tp->t_inpcb, ip, th);
|
|
}
|
|
|
|
/*
|
|
* Fill in fields, remembering maximum advertised
|
|
* window for use in delaying messages about window sizes.
|
|
* If resending a FIN, be sure not to use a new sequence number.
|
|
*/
|
|
if (flags & TH_FIN && tp->t_flags & TF_SENTFIN &&
|
|
tp->snd_nxt == tp->snd_max)
|
|
tp->snd_nxt--;
|
|
/*
|
|
* If we are doing retransmissions, then snd_nxt will
|
|
* not reflect the first unsent octet. For ACK only
|
|
* packets, we do not want the sequence number of the
|
|
* retransmitted packet, we want the sequence number
|
|
* of the next unsent octet. So, if there is no data
|
|
* (and no SYN or FIN), use snd_max instead of snd_nxt
|
|
* when filling in ti_seq. But if we are in persist
|
|
* state, snd_max might reflect one byte beyond the
|
|
* right edge of the window, so use snd_nxt in that
|
|
* case, since we know we aren't doing a retransmission.
|
|
* (retransmit and persist are mutually exclusive...)
|
|
*/
|
|
if (len || (flags & (TH_SYN|TH_FIN))
|
|
|| callout_active(tp->tt_persist))
|
|
th->th_seq = htonl(tp->snd_nxt);
|
|
else
|
|
th->th_seq = htonl(tp->snd_max);
|
|
th->th_ack = htonl(tp->rcv_nxt);
|
|
if (optlen) {
|
|
bcopy(opt, th + 1, optlen);
|
|
th->th_off = (sizeof (struct tcphdr) + optlen) >> 2;
|
|
}
|
|
th->th_flags = flags;
|
|
/*
|
|
* Calculate receive window. Don't shrink window,
|
|
* but avoid silly window syndrome.
|
|
*/
|
|
if (recwin < (long)(so->so_rcv.sb_hiwat / 4) &&
|
|
recwin < (long)tp->t_maxseg)
|
|
recwin = 0;
|
|
if (recwin < (long)(tp->rcv_adv - tp->rcv_nxt))
|
|
recwin = (long)(tp->rcv_adv - tp->rcv_nxt);
|
|
if (recwin > (long)TCP_MAXWIN << tp->rcv_scale)
|
|
recwin = (long)TCP_MAXWIN << tp->rcv_scale;
|
|
th->th_win = htons((u_short) (recwin >> tp->rcv_scale));
|
|
|
|
|
|
/*
|
|
* Adjust the RXWIN0SENT flag - indicate that we have advertised
|
|
* a 0 window. This may cause the remote transmitter to stall. This
|
|
* flag tells soreceive() to disable delayed acknowledgements when
|
|
* draining the buffer. This can occur if the receiver is attempting
|
|
* to read more data then can be buffered prior to transmitting on
|
|
* the connection.
|
|
*/
|
|
if (recwin == 0)
|
|
tp->t_flags |= TF_RXWIN0SENT;
|
|
else
|
|
tp->t_flags &= ~TF_RXWIN0SENT;
|
|
if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
|
|
th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt));
|
|
th->th_flags |= TH_URG;
|
|
} else
|
|
/*
|
|
* If no urgent pointer to send, then we pull
|
|
* the urgent pointer to the left edge of the send window
|
|
* so that it doesn't drift into the send window on sequence
|
|
* number wraparound.
|
|
*/
|
|
tp->snd_up = tp->snd_una; /* drag it along */
|
|
|
|
/*
|
|
* Put TCP length in extended header, and then
|
|
* checksum extended header and data.
|
|
*/
|
|
m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
/*
|
|
* ip6_plen is not need to be filled now, and will be filled
|
|
* in ip6_output.
|
|
*/
|
|
th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
|
|
sizeof(struct tcphdr) + optlen + len);
|
|
else
|
|
#endif /* INET6 */
|
|
{
|
|
m->m_pkthdr.csum_flags = CSUM_TCP;
|
|
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
|
|
th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
|
|
htons(sizeof(struct tcphdr) + IPPROTO_TCP + len + optlen));
|
|
|
|
/* IP version must be set here for ipv4/ipv6 checking later */
|
|
KASSERT(ip->ip_v == IPVERSION,
|
|
("%s: IP version incorrect: %d", __func__, ip->ip_v));
|
|
}
|
|
|
|
/*
|
|
* In transmit state, time the transmission and arrange for
|
|
* the retransmit. In persist state, just set snd_max.
|
|
*/
|
|
if (tp->t_force == 0 || !callout_active(tp->tt_persist)) {
|
|
tcp_seq startseq = tp->snd_nxt;
|
|
|
|
/*
|
|
* Advance snd_nxt over sequence space of this segment.
|
|
*/
|
|
if (flags & (TH_SYN|TH_FIN)) {
|
|
if (flags & TH_SYN)
|
|
tp->snd_nxt++;
|
|
if (flags & TH_FIN) {
|
|
tp->snd_nxt++;
|
|
tp->t_flags |= TF_SENTFIN;
|
|
}
|
|
}
|
|
tp->snd_nxt += len;
|
|
if (SEQ_GT(tp->snd_nxt, tp->snd_max)) {
|
|
tp->snd_max = tp->snd_nxt;
|
|
/*
|
|
* Time this transmission if not a retransmission and
|
|
* not currently timing anything.
|
|
*/
|
|
if (tp->t_rtttime == 0) {
|
|
tp->t_rtttime = ticks;
|
|
tp->t_rtseq = startseq;
|
|
tcpstat.tcps_segstimed++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Set retransmit timer if not currently set,
|
|
* and not doing a pure ack or a keep-alive probe.
|
|
* Initial value for retransmit timer is smoothed
|
|
* round-trip time + 2 * round-trip time variance.
|
|
* Initialize shift counter which is used for backoff
|
|
* of retransmit time.
|
|
*/
|
|
if (!callout_active(tp->tt_rexmt) &&
|
|
tp->snd_nxt != tp->snd_una) {
|
|
if (callout_active(tp->tt_persist)) {
|
|
callout_stop(tp->tt_persist);
|
|
tp->t_rxtshift = 0;
|
|
}
|
|
callout_reset(tp->tt_rexmt, tp->t_rxtcur,
|
|
tcp_timer_rexmt, tp);
|
|
}
|
|
} else {
|
|
/*
|
|
* Persist case, update snd_max but since we are in
|
|
* persist mode (no window) we do not update snd_nxt.
|
|
*/
|
|
int xlen = len;
|
|
if (flags & TH_SYN)
|
|
++xlen;
|
|
if (flags & TH_FIN) {
|
|
++xlen;
|
|
tp->t_flags |= TF_SENTFIN;
|
|
}
|
|
if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max))
|
|
tp->snd_max = tp->snd_nxt + len;
|
|
}
|
|
|
|
#ifdef TCPDEBUG
|
|
/*
|
|
* Trace.
|
|
*/
|
|
if (so->so_options & SO_DEBUG) {
|
|
u_short save = ipov->ih_len;
|
|
ipov->ih_len = htons(m->m_pkthdr.len /* - hdrlen + (th->th_off << 2) */);
|
|
tcp_trace(TA_OUTPUT, tp->t_state, tp, mtod(m, void *), th, 0);
|
|
ipov->ih_len = save;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Fill in IP length and desired time to live and
|
|
* send to IP level. There should be a better way
|
|
* to handle ttl and tos; we could keep them in
|
|
* the template, but need a way to checksum without them.
|
|
*/
|
|
/*
|
|
* m->m_pkthdr.len should have been set before cksum calcuration,
|
|
* because in6_cksum() need it.
|
|
*/
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
/*
|
|
* we separately set hoplimit for every segment, since the
|
|
* user might want to change the value via setsockopt.
|
|
* Also, desired default hop limit might be changed via
|
|
* Neighbor Discovery.
|
|
*/
|
|
ip6->ip6_hlim = in6_selecthlim(tp->t_inpcb, NULL);
|
|
|
|
/* TODO: IPv6 IP6TOS_ECT bit on */
|
|
#if defined(IPSEC) && !defined(FAST_IPSEC)
|
|
if (ipsec_setsocket(m, so) != 0) {
|
|
m_freem(m);
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
#endif /*IPSEC*/
|
|
error = ip6_output(m,
|
|
tp->t_inpcb->in6p_outputopts, NULL,
|
|
(so->so_options & SO_DONTROUTE), NULL, NULL,
|
|
tp->t_inpcb);
|
|
} else
|
|
#endif /* INET6 */
|
|
{
|
|
ip->ip_len = m->m_pkthdr.len;
|
|
#ifdef INET6
|
|
if (INP_CHECK_SOCKAF(so, AF_INET6))
|
|
ip->ip_ttl = in6_selecthlim(tp->t_inpcb, NULL);
|
|
#endif /* INET6 */
|
|
/*
|
|
* If we do path MTU discovery, then we set DF on every packet.
|
|
* This might not be the best thing to do according to RFC3390
|
|
* Section 2. However the tcp hostcache migitates the problem
|
|
* so it affects only the first tcp connection with a host.
|
|
*/
|
|
if (path_mtu_discovery)
|
|
ip->ip_off |= IP_DF;
|
|
|
|
error = ip_output(m, tp->t_inpcb->inp_options, NULL,
|
|
(so->so_options & SO_DONTROUTE), 0, tp->t_inpcb);
|
|
}
|
|
if (error) {
|
|
|
|
/*
|
|
* We know that the packet was lost, so back out the
|
|
* sequence number advance, if any.
|
|
*/
|
|
if (tp->t_force == 0 || !callout_active(tp->tt_persist)) {
|
|
/*
|
|
* No need to check for TH_FIN here because
|
|
* the TF_SENTFIN flag handles that case.
|
|
*/
|
|
if ((flags & TH_SYN) == 0)
|
|
tp->snd_nxt -= len;
|
|
}
|
|
|
|
out:
|
|
if (error == ENOBUFS) {
|
|
if (!callout_active(tp->tt_rexmt) &&
|
|
!callout_active(tp->tt_persist))
|
|
callout_reset(tp->tt_rexmt, tp->t_rxtcur,
|
|
tcp_timer_rexmt, tp);
|
|
tcp_quench(tp->t_inpcb, 0);
|
|
return (0);
|
|
}
|
|
if (error == EMSGSIZE) {
|
|
/*
|
|
* ip_output() will have already fixed the route
|
|
* for us. tcp_mtudisc() will, as its last action,
|
|
* initiate retransmission, so it is important to
|
|
* not do so here.
|
|
*/
|
|
tcp_mtudisc(tp->t_inpcb, 0);
|
|
return 0;
|
|
}
|
|
if ((error == EHOSTUNREACH || error == ENETDOWN)
|
|
&& TCPS_HAVERCVDSYN(tp->t_state)) {
|
|
tp->t_softerror = error;
|
|
return (0);
|
|
}
|
|
return (error);
|
|
}
|
|
tcpstat.tcps_sndtotal++;
|
|
|
|
/*
|
|
* Data sent (as far as we can tell).
|
|
* If this advertises a larger window than any other segment,
|
|
* then remember the size of the advertised window.
|
|
* Any pending ACK has now been sent.
|
|
*/
|
|
if (recwin > 0 && SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv))
|
|
tp->rcv_adv = tp->rcv_nxt + recwin;
|
|
tp->last_ack_sent = tp->rcv_nxt;
|
|
tp->t_flags &= ~(TF_ACKNOW | TF_DELACK);
|
|
if (callout_active(tp->tt_delack))
|
|
callout_stop(tp->tt_delack);
|
|
#if 0
|
|
/*
|
|
* This completely breaks TCP if newreno is turned on. What happens
|
|
* is that if delayed-acks are turned on on the receiver, this code
|
|
* on the transmitter effectively destroys the TCP window, forcing
|
|
* it to four packets (1.5Kx4 = 6K window).
|
|
*/
|
|
if (sendalot && (!tcp_do_newreno || --maxburst))
|
|
goto again;
|
|
#endif
|
|
if (sendalot)
|
|
goto again;
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
tcp_setpersist(tp)
|
|
register struct tcpcb *tp;
|
|
{
|
|
int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
|
|
int tt;
|
|
|
|
if (callout_active(tp->tt_rexmt))
|
|
panic("tcp_setpersist: retransmit pending");
|
|
/*
|
|
* Start/restart persistance timer.
|
|
*/
|
|
TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift],
|
|
TCPTV_PERSMIN, TCPTV_PERSMAX);
|
|
callout_reset(tp->tt_persist, tt, tcp_timer_persist, tp);
|
|
if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
|
|
tp->t_rxtshift++;
|
|
}
|