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/*
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 * Copyright (c) 1982, 1986, 1988, 1990, 1993
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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.
13 2f5f8996 aliguori
 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 *
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 *        @(#)tcp_output.c        8.3 (Berkeley) 12/30/93
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 * tcp_output.c,v 1.3 1994/09/15 10:36:55 davidg Exp
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 */
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/*
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 * Changes and additions relating to SLiRP
35 f0cbd3ec bellard
 * Copyright (c) 1995 Danny Gasparovski.
36 5fafdf24 ths
 *
37 5fafdf24 ths
 * Please read the file COPYRIGHT for the
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 * terms and conditions of the copyright.
39 f0cbd3ec bellard
 */
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#include <slirp.h>
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43 f0cbd3ec bellard
/*
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 * Since this is only used in "stats socket", we give meaning
45 f0cbd3ec bellard
 * names instead of the REAL names
46 f0cbd3ec bellard
 */
47 9634d903 blueswir1
const char * const tcpstates[] = {
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/*        "CLOSED",       "LISTEN",       "SYN_SENT",     "SYN_RCVD", */
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        "REDIRECT",        "LISTEN",        "SYN_SENT",     "SYN_RCVD",
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        "ESTABLISHED",  "CLOSE_WAIT",   "FIN_WAIT_1",   "CLOSING",
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        "LAST_ACK",     "FIN_WAIT_2",   "TIME_WAIT",
52 f0cbd3ec bellard
};
53 f0cbd3ec bellard
54 9634d903 blueswir1
static const u_char  tcp_outflags[TCP_NSTATES] = {
55 f0cbd3ec bellard
        TH_RST|TH_ACK, 0,      TH_SYN,        TH_SYN|TH_ACK,
56 5fafdf24 ths
        TH_ACK,        TH_ACK, TH_FIN|TH_ACK, TH_FIN|TH_ACK,
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        TH_FIN|TH_ACK, TH_ACK, TH_ACK,
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};
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#define MAX_TCPOPTLEN        32        /* max # bytes that go in options */
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63 f0cbd3ec bellard
/*
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 * Tcp output routine: figure out what should be sent and send it.
65 f0cbd3ec bellard
 */
66 f0cbd3ec bellard
int
67 511d2b14 blueswir1
tcp_output(struct tcpcb *tp)
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{
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        register struct socket *so = tp->t_socket;
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        register long len, win;
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        int off, flags, error;
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        register struct mbuf *m;
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        register struct tcpiphdr *ti;
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        u_char opt[MAX_TCPOPTLEN];
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        unsigned optlen, hdrlen;
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        int idle, sendalot;
77 5fafdf24 ths
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        DEBUG_CALL("tcp_output");
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        DEBUG_ARG("tp = %lx", (long )tp);
80 5fafdf24 ths
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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->snd_max == tp->snd_una);
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        if (idle && tp->t_idle >= 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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                tp->snd_cwnd = tp->t_maxseg;
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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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        win = min(tp->snd_wnd, tp->snd_cwnd);
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        flags = tcp_outflags[tp->t_state];
101 5fafdf24 ths
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        DEBUG_MISC((dfd, " --- tcp_output flags = 0x%x\n",flags));
103 5fafdf24 ths
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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 (win == 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 unset 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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                        win = 1;
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                } else {
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                        tp->t_timer[TCPT_PERSIST] = 0;
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                        tp->t_rxtshift = 0;
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                }
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        }
136 f0cbd3ec bellard
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        len = min(so->so_snd.sb_cc, win) - off;
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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 -1.  Otherwise, window shrank
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                 * after we sent into it.  If window shrank to 0,
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                 * cancel pending retransmit and pull snd_nxt
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                 * back to (closed) window.  We will enter persist
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                 * state below.  If the window didn't close completely,
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                 * just wait for an ACK.
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                 */
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                len = 0;
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                if (win == 0) {
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                        tp->t_timer[TCPT_REXMT] = 0;
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                        tp->snd_nxt = tp->snd_una;
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                }
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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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        win = sbspace(&so->so_rcv);
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        /*
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         * Sender silly window avoidance.  If connection is idle
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         * and can send all data, a maximum segment,
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         * at least a maximum default-size segment do it,
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         * or are forced, do it; otherwise don't bother.
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         * If peer's buffer is tiny, then send
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         * when window is at least half open.
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         * If retransmitting (possibly after persist timer forced us
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         * to send into a small window), then must resend.
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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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                if ((1 || idle || tp->t_flags & TF_NODELAY) &&
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                    len + off >= so->so_snd.sb_cc)
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                        goto send;
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                if (tp->t_force)
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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))
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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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         */
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        if (win > 0) {
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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(win, (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_datalen)
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                        goto send;
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        }
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        /*
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         * Send if we owe peer an ACK.
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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_SYN|TH_RST))
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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, or we're retransmitting the FIN,
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         * 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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         * tp->t_timer[TCPT_PERSIST]
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         *        is set 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.
242 f0cbd3ec bellard
         * tp->t_timer[TCPT_REXMT]
243 f0cbd3ec bellard
         *        is set when we are retransmitting
244 f0cbd3ec bellard
         * The output side is idle when both timers are zero.
245 f0cbd3ec bellard
         *
246 f0cbd3ec bellard
         * If send window is too small, there is data to transmit, and no
247 f0cbd3ec bellard
         * retransmit or persist is pending, then go to persist state.
248 f0cbd3ec bellard
         * If nothing happens soon, send when timer expires:
249 f0cbd3ec bellard
         * if window is nonzero, transmit what we can,
250 f0cbd3ec bellard
         * otherwise force out a byte.
251 f0cbd3ec bellard
         */
252 f0cbd3ec bellard
        if (so->so_snd.sb_cc && tp->t_timer[TCPT_REXMT] == 0 &&
253 f0cbd3ec bellard
            tp->t_timer[TCPT_PERSIST] == 0) {
254 f0cbd3ec bellard
                tp->t_rxtshift = 0;
255 f0cbd3ec bellard
                tcp_setpersist(tp);
256 f0cbd3ec bellard
        }
257 f0cbd3ec bellard
258 f0cbd3ec bellard
        /*
259 f0cbd3ec bellard
         * No reason to send a segment, just return.
260 f0cbd3ec bellard
         */
261 31a60e22 blueswir1
        STAT(tcpstat.tcps_didnuttin++);
262 5fafdf24 ths
263 f0cbd3ec bellard
        return (0);
264 f0cbd3ec bellard
265 f0cbd3ec bellard
send:
266 f0cbd3ec bellard
        /*
267 f0cbd3ec bellard
         * Before ESTABLISHED, force sending of initial options
268 f0cbd3ec bellard
         * unless TCP set not to do any options.
269 f0cbd3ec bellard
         * NOTE: we assume that the IP/TCP header plus TCP options
270 f0cbd3ec bellard
         * always fit in a single mbuf, leaving room for a maximum
271 f0cbd3ec bellard
         * link header, i.e.
272 f0cbd3ec bellard
         *        max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MHLEN
273 f0cbd3ec bellard
         */
274 f0cbd3ec bellard
        optlen = 0;
275 f0cbd3ec bellard
        hdrlen = sizeof (struct tcpiphdr);
276 f0cbd3ec bellard
        if (flags & TH_SYN) {
277 f0cbd3ec bellard
                tp->snd_nxt = tp->iss;
278 f0cbd3ec bellard
                if ((tp->t_flags & TF_NOOPT) == 0) {
279 f0cbd3ec bellard
                        u_int16_t mss;
280 f0cbd3ec bellard
281 f0cbd3ec bellard
                        opt[0] = TCPOPT_MAXSEG;
282 f0cbd3ec bellard
                        opt[1] = 4;
283 f0cbd3ec bellard
                        mss = htons((u_int16_t) tcp_mss(tp, 0));
284 f0cbd3ec bellard
                        memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss));
285 f0cbd3ec bellard
                        optlen = 4;
286 f0cbd3ec bellard
287 f0cbd3ec bellard
/*                        if ((tp->t_flags & TF_REQ_SCALE) &&
288 f0cbd3ec bellard
 *                            ((flags & TH_ACK) == 0 ||
289 f0cbd3ec bellard
 *                            (tp->t_flags & TF_RCVD_SCALE))) {
290 f0cbd3ec bellard
 *                                *((u_int32_t *) (opt + optlen)) = htonl(
291 f0cbd3ec bellard
 *                                        TCPOPT_NOP << 24 |
292 f0cbd3ec bellard
 *                                        TCPOPT_WINDOW << 16 |
293 f0cbd3ec bellard
 *                                        TCPOLEN_WINDOW << 8 |
294 f0cbd3ec bellard
 *                                        tp->request_r_scale);
295 f0cbd3ec bellard
 *                                optlen += 4;
296 f0cbd3ec bellard
 *                        }
297 f0cbd3ec bellard
 */
298 f0cbd3ec bellard
                }
299 f0cbd3ec bellard
         }
300 5fafdf24 ths
301 f0cbd3ec bellard
         /*
302 5fafdf24 ths
         * Send a timestamp and echo-reply if this is a SYN and our side
303 f0cbd3ec bellard
         * wants to use timestamps (TF_REQ_TSTMP is set) or both our side
304 f0cbd3ec bellard
         * and our peer have sent timestamps in our SYN's.
305 f0cbd3ec bellard
          */
306 f0cbd3ec bellard
/*         if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
307 f0cbd3ec bellard
 *             (flags & TH_RST) == 0 &&
308 f0cbd3ec bellard
 *            ((flags & (TH_SYN|TH_ACK)) == TH_SYN ||
309 f0cbd3ec bellard
 *             (tp->t_flags & TF_RCVD_TSTMP))) {
310 f0cbd3ec bellard
 *                u_int32_t *lp = (u_int32_t *)(opt + optlen);
311 f0cbd3ec bellard
 *
312 f0cbd3ec bellard
 *                / * Form timestamp option as shown in appendix A of RFC 1323. *  /
313 f0cbd3ec bellard
 *                *lp++ = htonl(TCPOPT_TSTAMP_HDR);
314 f0cbd3ec bellard
 *                *lp++ = htonl(tcp_now);
315 f0cbd3ec bellard
 *                *lp   = htonl(tp->ts_recent);
316 f0cbd3ec bellard
 *                optlen += TCPOLEN_TSTAMP_APPA;
317 f0cbd3ec bellard
 *        }
318 f0cbd3ec bellard
 */
319 f0cbd3ec bellard
         hdrlen += optlen;
320 5fafdf24 ths
321 f0cbd3ec bellard
        /*
322 f0cbd3ec bellard
         * Adjust data length if insertion of options will
323 f0cbd3ec bellard
         * bump the packet length beyond the t_maxseg length.
324 f0cbd3ec bellard
         */
325 f0cbd3ec bellard
         if (len > tp->t_maxseg - optlen) {
326 f0cbd3ec bellard
                len = tp->t_maxseg - optlen;
327 f0cbd3ec bellard
                sendalot = 1;
328 f0cbd3ec bellard
         }
329 f0cbd3ec bellard
330 f0cbd3ec bellard
        /*
331 f0cbd3ec bellard
         * Grab a header mbuf, attaching a copy of data to
332 f0cbd3ec bellard
         * be transmitted, and initialize the header from
333 f0cbd3ec bellard
         * the template for sends on this connection.
334 f0cbd3ec bellard
         */
335 f0cbd3ec bellard
        if (len) {
336 f0cbd3ec bellard
                if (tp->t_force && len == 1)
337 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndprobe++);
338 f0cbd3ec bellard
                else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) {
339 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndrexmitpack++);
340 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndrexmitbyte += len);
341 f0cbd3ec bellard
                } else {
342 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndpack++);
343 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndbyte += len);
344 f0cbd3ec bellard
                }
345 f0cbd3ec bellard
346 f0cbd3ec bellard
                m = m_get();
347 f0cbd3ec bellard
                if (m == NULL) {
348 f0cbd3ec bellard
/*                        error = ENOBUFS; */
349 f0cbd3ec bellard
                        error = 1;
350 f0cbd3ec bellard
                        goto out;
351 f0cbd3ec bellard
                }
352 9634d903 blueswir1
                m->m_data += IF_MAXLINKHDR;
353 f0cbd3ec bellard
                m->m_len = hdrlen;
354 3b46e624 ths
355 5fafdf24 ths
                /*
356 f0cbd3ec bellard
                 * This will always succeed, since we make sure our mbufs
357 f0cbd3ec bellard
                 * are big enough to hold one MSS packet + header + ... etc.
358 f0cbd3ec bellard
                 */
359 f0cbd3ec bellard
/*                if (len <= MHLEN - hdrlen - max_linkhdr) { */
360 f0cbd3ec bellard
361 f0cbd3ec bellard
                        sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
362 f0cbd3ec bellard
                        m->m_len += len;
363 f0cbd3ec bellard
364 f0cbd3ec bellard
/*                } else {
365 f0cbd3ec bellard
 *                        m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
366 f0cbd3ec bellard
 *                        if (m->m_next == 0)
367 f0cbd3ec bellard
 *                                len = 0;
368 f0cbd3ec bellard
 *                }
369 f0cbd3ec bellard
 */
370 f0cbd3ec bellard
                /*
371 f0cbd3ec bellard
                 * If we're sending everything we've got, set PUSH.
372 f0cbd3ec bellard
                 * (This will keep happy those implementations which only
373 f0cbd3ec bellard
                 * give data to the user when a buffer fills or
374 f0cbd3ec bellard
                 * a PUSH comes in.)
375 f0cbd3ec bellard
                 */
376 f0cbd3ec bellard
                if (off + len == so->so_snd.sb_cc)
377 f0cbd3ec bellard
                        flags |= TH_PUSH;
378 f0cbd3ec bellard
        } else {
379 f0cbd3ec bellard
                if (tp->t_flags & TF_ACKNOW)
380 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndacks++);
381 f0cbd3ec bellard
                else if (flags & (TH_SYN|TH_FIN|TH_RST))
382 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndctrl++);
383 f0cbd3ec bellard
                else if (SEQ_GT(tp->snd_up, tp->snd_una))
384 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndurg++);
385 f0cbd3ec bellard
                else
386 31a60e22 blueswir1
                        STAT(tcpstat.tcps_sndwinup++);
387 f0cbd3ec bellard
388 f0cbd3ec bellard
                m = m_get();
389 f0cbd3ec bellard
                if (m == NULL) {
390 f0cbd3ec bellard
/*                        error = ENOBUFS; */
391 f0cbd3ec bellard
                        error = 1;
392 f0cbd3ec bellard
                        goto out;
393 f0cbd3ec bellard
                }
394 9634d903 blueswir1
                m->m_data += IF_MAXLINKHDR;
395 f0cbd3ec bellard
                m->m_len = hdrlen;
396 f0cbd3ec bellard
        }
397 f0cbd3ec bellard
398 f0cbd3ec bellard
        ti = mtod(m, struct tcpiphdr *);
399 5fafdf24 ths
400 f0cbd3ec bellard
        memcpy((caddr_t)ti, &tp->t_template, sizeof (struct tcpiphdr));
401 f0cbd3ec bellard
402 f0cbd3ec bellard
        /*
403 f0cbd3ec bellard
         * Fill in fields, remembering maximum advertised
404 f0cbd3ec bellard
         * window for use in delaying messages about window sizes.
405 f0cbd3ec bellard
         * If resending a FIN, be sure not to use a new sequence number.
406 f0cbd3ec bellard
         */
407 5fafdf24 ths
        if (flags & TH_FIN && tp->t_flags & TF_SENTFIN &&
408 f0cbd3ec bellard
            tp->snd_nxt == tp->snd_max)
409 f0cbd3ec bellard
                tp->snd_nxt--;
410 f0cbd3ec bellard
        /*
411 f0cbd3ec bellard
         * If we are doing retransmissions, then snd_nxt will
412 f0cbd3ec bellard
         * not reflect the first unsent octet.  For ACK only
413 f0cbd3ec bellard
         * packets, we do not want the sequence number of the
414 f0cbd3ec bellard
         * retransmitted packet, we want the sequence number
415 f0cbd3ec bellard
         * of the next unsent octet.  So, if there is no data
416 f0cbd3ec bellard
         * (and no SYN or FIN), use snd_max instead of snd_nxt
417 f0cbd3ec bellard
         * when filling in ti_seq.  But if we are in persist
418 f0cbd3ec bellard
         * state, snd_max might reflect one byte beyond the
419 f0cbd3ec bellard
         * right edge of the window, so use snd_nxt in that
420 f0cbd3ec bellard
         * case, since we know we aren't doing a retransmission.
421 f0cbd3ec bellard
         * (retransmit and persist are mutually exclusive...)
422 f0cbd3ec bellard
         */
423 f0cbd3ec bellard
        if (len || (flags & (TH_SYN|TH_FIN)) || tp->t_timer[TCPT_PERSIST])
424 f0cbd3ec bellard
                ti->ti_seq = htonl(tp->snd_nxt);
425 f0cbd3ec bellard
        else
426 f0cbd3ec bellard
                ti->ti_seq = htonl(tp->snd_max);
427 f0cbd3ec bellard
        ti->ti_ack = htonl(tp->rcv_nxt);
428 f0cbd3ec bellard
        if (optlen) {
429 f0cbd3ec bellard
                memcpy((caddr_t)(ti + 1), (caddr_t)opt, optlen);
430 f0cbd3ec bellard
                ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2;
431 f0cbd3ec bellard
        }
432 f0cbd3ec bellard
        ti->ti_flags = flags;
433 f0cbd3ec bellard
        /*
434 f0cbd3ec bellard
         * Calculate receive window.  Don't shrink window,
435 f0cbd3ec bellard
         * but avoid silly window syndrome.
436 f0cbd3ec bellard
         */
437 f0cbd3ec bellard
        if (win < (long)(so->so_rcv.sb_datalen / 4) && win < (long)tp->t_maxseg)
438 f0cbd3ec bellard
                win = 0;
439 f0cbd3ec bellard
        if (win > (long)TCP_MAXWIN << tp->rcv_scale)
440 f0cbd3ec bellard
                win = (long)TCP_MAXWIN << tp->rcv_scale;
441 f0cbd3ec bellard
        if (win < (long)(tp->rcv_adv - tp->rcv_nxt))
442 f0cbd3ec bellard
                win = (long)(tp->rcv_adv - tp->rcv_nxt);
443 f0cbd3ec bellard
        ti->ti_win = htons((u_int16_t) (win>>tp->rcv_scale));
444 5fafdf24 ths
445 f0cbd3ec bellard
        if (SEQ_GT(tp->snd_up, tp->snd_una)) {
446 f0cbd3ec bellard
                ti->ti_urp = htons((u_int16_t)(tp->snd_up - ntohl(ti->ti_seq)));
447 3b46e624 ths
#ifdef notdef
448 f0cbd3ec bellard
        if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
449 f0cbd3ec bellard
                ti->ti_urp = htons((u_int16_t)(tp->snd_up - tp->snd_nxt));
450 f0cbd3ec bellard
#endif
451 f0cbd3ec bellard
                ti->ti_flags |= TH_URG;
452 f0cbd3ec bellard
        } else
453 f0cbd3ec bellard
                /*
454 f0cbd3ec bellard
                 * If no urgent pointer to send, then we pull
455 f0cbd3ec bellard
                 * the urgent pointer to the left edge of the send window
456 f0cbd3ec bellard
                 * so that it doesn't drift into the send window on sequence
457 f0cbd3ec bellard
                 * number wraparound.
458 f0cbd3ec bellard
                 */
459 f0cbd3ec bellard
                tp->snd_up = tp->snd_una;                /* drag it along */
460 f0cbd3ec bellard
461 f0cbd3ec bellard
        /*
462 f0cbd3ec bellard
         * Put TCP length in extended header, and then
463 f0cbd3ec bellard
         * checksum extended header and data.
464 f0cbd3ec bellard
         */
465 f0cbd3ec bellard
        if (len + optlen)
466 f0cbd3ec bellard
                ti->ti_len = htons((u_int16_t)(sizeof (struct tcphdr) +
467 f0cbd3ec bellard
                    optlen + len));
468 f0cbd3ec bellard
        ti->ti_sum = cksum(m, (int)(hdrlen + len));
469 f0cbd3ec bellard
470 f0cbd3ec bellard
        /*
471 f0cbd3ec bellard
         * In transmit state, time the transmission and arrange for
472 f0cbd3ec bellard
         * the retransmit.  In persist state, just set snd_max.
473 f0cbd3ec bellard
         */
474 f0cbd3ec bellard
        if (tp->t_force == 0 || tp->t_timer[TCPT_PERSIST] == 0) {
475 f0cbd3ec bellard
                tcp_seq startseq = tp->snd_nxt;
476 f0cbd3ec bellard
477 f0cbd3ec bellard
                /*
478 f0cbd3ec bellard
                 * Advance snd_nxt over sequence space of this segment.
479 f0cbd3ec bellard
                 */
480 f0cbd3ec bellard
                if (flags & (TH_SYN|TH_FIN)) {
481 f0cbd3ec bellard
                        if (flags & TH_SYN)
482 f0cbd3ec bellard
                                tp->snd_nxt++;
483 f0cbd3ec bellard
                        if (flags & TH_FIN) {
484 f0cbd3ec bellard
                                tp->snd_nxt++;
485 f0cbd3ec bellard
                                tp->t_flags |= TF_SENTFIN;
486 f0cbd3ec bellard
                        }
487 f0cbd3ec bellard
                }
488 f0cbd3ec bellard
                tp->snd_nxt += len;
489 f0cbd3ec bellard
                if (SEQ_GT(tp->snd_nxt, tp->snd_max)) {
490 f0cbd3ec bellard
                        tp->snd_max = tp->snd_nxt;
491 f0cbd3ec bellard
                        /*
492 f0cbd3ec bellard
                         * Time this transmission if not a retransmission and
493 f0cbd3ec bellard
                         * not currently timing anything.
494 f0cbd3ec bellard
                         */
495 f0cbd3ec bellard
                        if (tp->t_rtt == 0) {
496 f0cbd3ec bellard
                                tp->t_rtt = 1;
497 f0cbd3ec bellard
                                tp->t_rtseq = startseq;
498 31a60e22 blueswir1
                                STAT(tcpstat.tcps_segstimed++);
499 f0cbd3ec bellard
                        }
500 f0cbd3ec bellard
                }
501 f0cbd3ec bellard
502 f0cbd3ec bellard
                /*
503 f0cbd3ec bellard
                 * Set retransmit timer if not currently set,
504 f0cbd3ec bellard
                 * and not doing an ack or a keep-alive probe.
505 f0cbd3ec bellard
                 * Initial value for retransmit timer is smoothed
506 f0cbd3ec bellard
                 * round-trip time + 2 * round-trip time variance.
507 f0cbd3ec bellard
                 * Initialize shift counter which is used for backoff
508 f0cbd3ec bellard
                 * of retransmit time.
509 f0cbd3ec bellard
                 */
510 f0cbd3ec bellard
                if (tp->t_timer[TCPT_REXMT] == 0 &&
511 f0cbd3ec bellard
                    tp->snd_nxt != tp->snd_una) {
512 f0cbd3ec bellard
                        tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
513 f0cbd3ec bellard
                        if (tp->t_timer[TCPT_PERSIST]) {
514 f0cbd3ec bellard
                                tp->t_timer[TCPT_PERSIST] = 0;
515 f0cbd3ec bellard
                                tp->t_rxtshift = 0;
516 f0cbd3ec bellard
                        }
517 f0cbd3ec bellard
                }
518 f0cbd3ec bellard
        } else
519 f0cbd3ec bellard
                if (SEQ_GT(tp->snd_nxt + len, tp->snd_max))
520 f0cbd3ec bellard
                        tp->snd_max = tp->snd_nxt + len;
521 f0cbd3ec bellard
522 f0cbd3ec bellard
        /*
523 f0cbd3ec bellard
         * Fill in IP length and desired time to live and
524 f0cbd3ec bellard
         * send to IP level.  There should be a better way
525 f0cbd3ec bellard
         * to handle ttl and tos; we could keep them in
526 f0cbd3ec bellard
         * the template, but need a way to checksum without them.
527 f0cbd3ec bellard
         */
528 f0cbd3ec bellard
        m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
529 5fafdf24 ths
530 f0cbd3ec bellard
    {
531 3b46e624 ths
532 f0cbd3ec bellard
        ((struct ip *)ti)->ip_len = m->m_len;
533 f0cbd3ec bellard
534 9634d903 blueswir1
        ((struct ip *)ti)->ip_ttl = IPDEFTTL;
535 f0cbd3ec bellard
        ((struct ip *)ti)->ip_tos = so->so_iptos;
536 3b46e624 ths
537 f0cbd3ec bellard
/* #if BSD >= 43 */
538 f0cbd3ec bellard
        /* Don't do IP options... */
539 f0cbd3ec bellard
/*        error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route,
540 f0cbd3ec bellard
 *            so->so_options & SO_DONTROUTE, 0);
541 f0cbd3ec bellard
 */
542 f0cbd3ec bellard
        error = ip_output(so, m);
543 f0cbd3ec bellard
544 f0cbd3ec bellard
/* #else
545 5fafdf24 ths
 *        error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route,
546 f0cbd3ec bellard
 *            so->so_options & SO_DONTROUTE);
547 f0cbd3ec bellard
 * #endif
548 f0cbd3ec bellard
 */
549 f0cbd3ec bellard
    }
550 f0cbd3ec bellard
        if (error) {
551 f0cbd3ec bellard
out:
552 f0cbd3ec bellard
/*                if (error == ENOBUFS) {
553 f0cbd3ec bellard
 *                        tcp_quench(tp->t_inpcb, 0);
554 f0cbd3ec bellard
 *                        return (0);
555 f0cbd3ec bellard
 *                }
556 f0cbd3ec bellard
 */
557 f0cbd3ec bellard
/*                if ((error == EHOSTUNREACH || error == ENETDOWN)
558 f0cbd3ec bellard
 *                    && TCPS_HAVERCVDSYN(tp->t_state)) {
559 f0cbd3ec bellard
 *                        tp->t_softerror = error;
560 f0cbd3ec bellard
 *                        return (0);
561 f0cbd3ec bellard
 *                }
562 f0cbd3ec bellard
 */
563 f0cbd3ec bellard
                return (error);
564 f0cbd3ec bellard
        }
565 31a60e22 blueswir1
        STAT(tcpstat.tcps_sndtotal++);
566 f0cbd3ec bellard
567 f0cbd3ec bellard
        /*
568 f0cbd3ec bellard
         * Data sent (as far as we can tell).
569 f0cbd3ec bellard
         * If this advertises a larger window than any other segment,
570 f0cbd3ec bellard
         * then remember the size of the advertised window.
571 f0cbd3ec bellard
         * Any pending ACK has now been sent.
572 f0cbd3ec bellard
         */
573 f0cbd3ec bellard
        if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
574 f0cbd3ec bellard
                tp->rcv_adv = tp->rcv_nxt + win;
575 f0cbd3ec bellard
        tp->last_ack_sent = tp->rcv_nxt;
576 f0cbd3ec bellard
        tp->t_flags &= ~(TF_ACKNOW|TF_DELACK);
577 f0cbd3ec bellard
        if (sendalot)
578 f0cbd3ec bellard
                goto again;
579 f0cbd3ec bellard
580 f0cbd3ec bellard
        return (0);
581 f0cbd3ec bellard
}
582 f0cbd3ec bellard
583 f0cbd3ec bellard
void
584 511d2b14 blueswir1
tcp_setpersist(struct tcpcb *tp)
585 f0cbd3ec bellard
{
586 f0cbd3ec bellard
    int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
587 f0cbd3ec bellard
588 f0cbd3ec bellard
/*        if (tp->t_timer[TCPT_REXMT])
589 f0cbd3ec bellard
 *                panic("tcp_output REXMT");
590 f0cbd3ec bellard
 */
591 f0cbd3ec bellard
        /*
592 f0cbd3ec bellard
         * Start/restart persistence timer.
593 f0cbd3ec bellard
         */
594 f0cbd3ec bellard
        TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
595 f0cbd3ec bellard
            t * tcp_backoff[tp->t_rxtshift],
596 f0cbd3ec bellard
            TCPTV_PERSMIN, TCPTV_PERSMAX);
597 f0cbd3ec bellard
        if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
598 f0cbd3ec bellard
                tp->t_rxtshift++;
599 f0cbd3ec bellard
}