| 1 | /*
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| 2 | * Copyright (c) 1982, 1986, 1988, 1990, 1993
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| 3 | * The Regents of the University of California. All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | * 1. Redistributions of source code must retain the above copyright
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| 9 | * notice, this list of conditions and the following disclaimer.
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| 10 | * 2. Redistributions in binary form must reproduce the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer in the
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| 12 | * documentation and/or other materials provided with the distribution.
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| 13 | * 3. All advertising materials mentioning features or use of this software
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| 14 | * must display the following acknowledgement:
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| 15 | * This product includes software developed by the University of
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| 16 | * California, Berkeley and its contributors.
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| 17 | * 4. Neither the name of the University nor the names of its contributors
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| 18 | * may be used to endorse or promote products derived from this software
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| 19 | * without specific prior written permission.
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| 20 | *
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| 21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 31 | * SUCH DAMAGE.
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| 32 | *
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| 33 | * @(#)tcp_output.c 8.3 (Berkeley) 12/30/93
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| 34 | * tcp_output.c,v 1.3 1994/09/15 10:36:55 davidg Exp
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| 35 | */
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| 36 |
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| 37 | /*
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| 38 | * Changes and additions relating to SLiRP
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| 39 | * Copyright (c) 1995 Danny Gasparovski.
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| 40 | *
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| 41 | * Please read the file COPYRIGHT for the
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| 42 | * terms and conditions of the copyright.
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| 43 | */
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| 44 |
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| 45 | #include <slirp.h>
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| 46 |
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| 47 | /*
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| 48 | * Since this is only used in "stats socket", we give meaning
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| 49 | * names instead of the REAL names
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| 50 | */
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| 51 | const char * const tcpstates[] =
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| 52 | {
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| 53 | /* "CLOSED", "LISTEN", "SYN_SENT", "SYN_RCVD", */
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| 54 | "REDIRECT", "LISTEN", "SYN_SENT", "SYN_RCVD",
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| 55 | "ESTABLISHED", "CLOSE_WAIT", "FIN_WAIT_1", "CLOSING",
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| 56 | "LAST_ACK", "FIN_WAIT_2", "TIME_WAIT",
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| 57 | };
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| 58 |
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| 59 | static const u_char tcp_outflags[TCP_NSTATES] =
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| 60 | {
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| 61 | TH_RST|TH_ACK, 0, TH_SYN, TH_SYN|TH_ACK,
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| 62 | TH_ACK, TH_ACK, TH_FIN|TH_ACK, TH_FIN|TH_ACK,
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| 63 | TH_FIN|TH_ACK, TH_ACK, TH_ACK,
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| 64 | };
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| 65 |
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| 66 |
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| 67 | #define MAX_TCPOPTLEN 32 /* max # bytes that go in options */
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| 68 |
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| 69 | /*
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| 70 | * Tcp output routine: figure out what should be sent and send it.
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| 71 | */
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| 72 | int
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| 73 | tcp_output(PNATState pData, register struct tcpcb *tp)
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| 74 | {
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| 75 | register struct socket *so = tp->t_socket;
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| 76 | register long len, win;
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| 77 | int off, flags, error;
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| 78 | register struct mbuf *m;
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| 79 | register struct tcpiphdr *ti;
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| 80 | u_char opt[MAX_TCPOPTLEN];
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| 81 | unsigned optlen, hdrlen;
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| 82 | int idle, sendalot;
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| 83 |
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| 84 | DEBUG_CALL("tcp_output");
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| 85 | DEBUG_ARG("tp = %lx", (long )tp);
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| 86 |
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| 87 | /*
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| 88 | * Determine length of data that should be transmitted,
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| 89 | * and flags that will be used.
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| 90 | * If there is some data or critical controls (SYN, RST)
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| 91 | * to send, then transmit; otherwise, investigate further.
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| 92 | */
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| 93 | idle = (tp->snd_max == tp->snd_una);
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| 94 | if (idle && tp->t_idle >= tp->t_rxtcur)
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| 95 | /*
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| 96 | * We have been idle for "a while" and no acks are
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| 97 | * expected to clock out any data we send --
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| 98 | * slow start to get ack "clock" running again.
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| 99 | */
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| 100 | tp->snd_cwnd = tp->t_maxseg;
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| 101 |
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| 102 | again:
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| 103 | sendalot = 0;
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| 104 | off = tp->snd_nxt - tp->snd_una;
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| 105 | win = min(tp->snd_wnd, tp->snd_cwnd);
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| 106 |
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| 107 | flags = tcp_outflags[tp->t_state];
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| 108 |
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| 109 | DEBUG_MISC((dfd, " --- tcp_output flags = 0x%x\n",flags));
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| 110 |
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| 111 | /*
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| 112 | * If in persist timeout with window of 0, send 1 byte.
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| 113 | * Otherwise, if window is small but nonzero
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| 114 | * and timer expired, we will send what we can
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| 115 | * and go to transmit state.
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| 116 | */
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| 117 | if (tp->t_force)
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| 118 | {
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| 119 | if (win == 0)
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| 120 | {
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| 121 | /*
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| 122 | * If we still have some data to send, then
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| 123 | * clear the FIN bit. Usually this would
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| 124 | * happen below when it realizes that we
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| 125 | * aren't sending all the data. However,
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| 126 | * if we have exactly 1 byte of unset data,
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| 127 | * then it won't clear the FIN bit below,
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| 128 | * and if we are in persist state, we wind
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| 129 | * up sending the packet without recording
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| 130 | * that we sent the FIN bit.
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| 131 | *
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| 132 | * We can't just blindly clear the FIN bit,
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| 133 | * because if we don't have any more data
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| 134 | * to send then the probe will be the FIN
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| 135 | * itself.
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| 136 | */
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| 137 | if (off < so->so_snd.sb_cc)
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| 138 | flags &= ~TH_FIN;
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| 139 | win = 1;
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| 140 | }
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| 141 | else
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| 142 | {
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| 143 | tp->t_timer[TCPT_PERSIST] = 0;
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| 144 | tp->t_rxtshift = 0;
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| 145 | }
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| 146 | }
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| 147 |
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| 148 | len = min(so->so_snd.sb_cc, win) - off;
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| 149 | if (len < 0)
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| 150 | {
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| 151 | /*
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| 152 | * If FIN has been sent but not acked,
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| 153 | * but we haven't been called to retransmit,
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| 154 | * len will be -1. Otherwise, window shrank
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| 155 | * after we sent into it. If window shrank to 0,
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| 156 | * cancel pending retransmit and pull snd_nxt
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| 157 | * back to (closed) window. We will enter persist
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| 158 | * state below. If the window didn't close completely,
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| 159 | * just wait for an ACK.
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| 160 | */
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| 161 | len = 0;
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| 162 | if (win == 0)
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| 163 | {
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| 164 | tp->t_timer[TCPT_REXMT] = 0;
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| 165 | tp->snd_nxt = tp->snd_una;
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| 166 | }
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| 167 | }
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| 168 | if (len > tp->t_maxseg)
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| 169 | {
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| 170 | len = tp->t_maxseg;
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| 171 | sendalot = 1;
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| 172 | }
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| 173 | if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc))
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| 174 | flags &= ~TH_FIN;
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| 175 |
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| 176 | win = sbspace(&so->so_rcv);
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| 177 |
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| 178 | /*
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| 179 | * Sender silly window avoidance. If connection is idle
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| 180 | * and can send all data, a maximum segment,
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| 181 | * at least a maximum default-size segment do it,
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| 182 | * or are forced, do it; otherwise don't bother.
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| 183 | * If peer's buffer is tiny, then send
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| 184 | * when window is at least half open.
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| 185 | * If retransmitting (possibly after persist timer forced us
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| 186 | * to send into a small window), then must resend.
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| 187 | */
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| 188 | if (len)
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| 189 | {
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| 190 | if (len == tp->t_maxseg)
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| 191 | goto send;
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| 192 | if ((1 || idle || tp->t_flags & TF_NODELAY) &&
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| 193 | len + off >= so->so_snd.sb_cc)
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| 194 | goto send;
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| 195 | if (tp->t_force)
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| 196 | goto send;
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| 197 | if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
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| 198 | goto send;
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| 199 | if (SEQ_LT(tp->snd_nxt, tp->snd_max))
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| 200 | goto send;
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| 201 | }
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| 202 |
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| 203 | /*
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| 204 | * Compare available window to amount of window
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| 205 | * known to peer (as advertised window less
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| 206 | * next expected input). If the difference is at least two
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| 207 | * max size segments, or at least 50% of the maximum possible
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| 208 | * window, then want to send a window update to peer.
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| 209 | */
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| 210 | if (win > 0)
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| 211 | {
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| 212 | /*
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| 213 | * "adv" is the amount we can increase the window,
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| 214 | * taking into account that we are limited by
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| 215 | * TCP_MAXWIN << tp->rcv_scale.
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| 216 | */
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| 217 | long adv = min(win,
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| 218 | (long)TCP_MAXWIN << tp->rcv_scale) -
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| 219 | (tp->rcv_adv - tp->rcv_nxt);
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| 220 |
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| 221 | if (adv >= (long) (2 * tp->t_maxseg))
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| 222 | goto send;
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| 223 | if (2 * adv >= (long) so->so_rcv.sb_datalen)
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| 224 | goto send;
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| 225 | }
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| 226 |
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| 227 | /*
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| 228 | * Send if we owe peer an ACK.
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| 229 | */
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| 230 | if (tp->t_flags & TF_ACKNOW)
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| 231 | goto send;
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| 232 | if (flags & (TH_SYN|TH_RST))
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| 233 | goto send;
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| 234 | if (SEQ_GT(tp->snd_up, tp->snd_una))
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| 235 | goto send;
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| 236 | /*
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| 237 | * If our state indicates that FIN should be sent
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| 238 | * and we have not yet done so, or we're retransmitting the FIN,
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| 239 | * then we need to send.
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| 240 | */
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| 241 | if ( flags & TH_FIN
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| 242 | && ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una))
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| 243 | goto send;
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| 244 |
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| 245 | /*
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| 246 | * TCP window updates are not reliable, rather a polling protocol
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| 247 | * using ``persist'' packets is used to insure receipt of window
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| 248 | * updates. The three ``states'' for the output side are:
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| 249 | * idle not doing retransmits or persists
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| 250 | * persisting to move a small or zero window
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| 251 | * (re)transmitting and thereby not persisting
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| 252 | *
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| 253 | * tp->t_timer[TCPT_PERSIST]
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| 254 | * is set when we are in persist state.
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| 255 | * tp->t_force
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| 256 | * is set when we are called to send a persist packet.
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| 257 | * tp->t_timer[TCPT_REXMT]
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| 258 | * is set when we are retransmitting
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| 259 | * The output side is idle when both timers are zero.
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| 260 | *
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| 261 | * If send window is too small, there is data to transmit, and no
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| 262 | * retransmit or persist is pending, then go to persist state.
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| 263 | * If nothing happens soon, send when timer expires:
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| 264 | * if window is nonzero, transmit what we can,
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| 265 | * otherwise force out a byte.
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| 266 | */
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| 267 | if ( so->so_snd.sb_cc
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| 268 | && tp->t_timer[TCPT_REXMT] == 0
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| 269 | && tp->t_timer[TCPT_PERSIST] == 0)
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| 270 | {
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| 271 | tp->t_rxtshift = 0;
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| 272 | tcp_setpersist(tp);
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| 273 | }
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| 274 |
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| 275 | /*
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| 276 | * No reason to send a segment, just return.
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| 277 | */
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| 278 | tcpstat.tcps_didnuttin++;
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| 279 |
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| 280 | return (0);
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| 281 |
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| 282 | send:
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| 283 | /*
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| 284 | * Before ESTABLISHED, force sending of initial options
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| 285 | * unless TCP set not to do any options.
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| 286 | * NOTE: we assume that the IP/TCP header plus TCP options
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| 287 | * always fit in a single mbuf, leaving room for a maximum
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| 288 | * link header, i.e.
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| 289 | * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MHLEN
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| 290 | */
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| 291 | optlen = 0;
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| 292 | hdrlen = sizeof (struct tcpiphdr);
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| 293 | if (flags & TH_SYN)
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| 294 | {
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| 295 | tp->snd_nxt = tp->iss;
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| 296 | if ((tp->t_flags & TF_NOOPT) == 0)
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| 297 | {
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| 298 | u_int16_t mss;
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| 299 |
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| 300 | opt[0] = TCPOPT_MAXSEG;
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| 301 | opt[1] = 4;
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| 302 | mss = htons((u_int16_t) tcp_mss(pData, tp, 0));
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| 303 | memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss));
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| 304 | optlen = 4;
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| 305 |
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| 306 | #if 0
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| 307 | if ( (tp->t_flags & TF_REQ_SCALE)
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| 308 | && ( (flags & TH_ACK) == 0
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| 309 | || (tp->t_flags & TF_RCVD_SCALE)))
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| 310 | {
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| 311 | *((u_int32_t *) (opt + optlen)) = htonl( TCPOPT_NOP << 24
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| 312 | | TCPOPT_WINDOW << 16
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| 313 | | TCPOLEN_WINDOW << 8
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| 314 | | tp->request_r_scale);
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| 315 | optlen += 4;
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| 316 | }
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| 317 | #endif
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| 318 | }
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| 319 | }
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| 320 |
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| 321 | /*
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| 322 | * Send a timestamp and echo-reply if this is a SYN and our side
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| 323 | * wants to use timestamps (TF_REQ_TSTMP is set) or both our side
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| 324 | * and our peer have sent timestamps in our SYN's.
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| 325 | */
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| 326 | #if 0
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| 327 | if ( (tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP
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| 328 | && (flags & TH_RST) == 0
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| 329 | && ( (flags & (TH_SYN|TH_ACK)) == TH_SYN
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| 330 | || (tp->t_flags & TF_RCVD_TSTMP)))
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| 331 | {
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| 332 | u_int32_t *lp = (u_int32_t *)(opt + optlen);
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| 333 |
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| 334 | /* Form timestamp option as shown in appendix A of RFC 1323. */
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| 335 | *lp++ = htonl(TCPOPT_TSTAMP_HDR);
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| 336 | *lp++ = htonl(tcp_now);
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| 337 | *lp = htonl(tp->ts_recent);
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| 338 | optlen += TCPOLEN_TSTAMP_APPA;
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| 339 | }
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| 340 | #endif
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| 341 | hdrlen += optlen;
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| 342 |
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| 343 | /*
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| 344 | * Adjust data length if insertion of options will
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| 345 | * bump the packet length beyond the t_maxseg length.
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| 346 | */
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| 347 | if (len > tp->t_maxseg - optlen)
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| 348 | {
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| 349 | len = tp->t_maxseg - optlen;
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| 350 | sendalot = 1;
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| 351 | }
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| 352 |
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| 353 | /*
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| 354 | * Grab a header mbuf, attaching a copy of data to
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| 355 | * be transmitted, and initialize the header from
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| 356 | * the template for sends on this connection.
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| 357 | */
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| 358 | if (len)
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| 359 | {
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| 360 | if (tp->t_force && len == 1)
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| 361 | tcpstat.tcps_sndprobe++;
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| 362 | else if (SEQ_LT(tp->snd_nxt, tp->snd_max))
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| 363 | {
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| 364 | tcpstat.tcps_sndrexmitpack++;
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| 365 | tcpstat.tcps_sndrexmitbyte += len;
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| 366 | }
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| 367 | else
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| 368 | {
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| 369 | tcpstat.tcps_sndpack++;
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| 370 | tcpstat.tcps_sndbyte += len;
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| 371 | }
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| 372 |
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| 373 | m = m_get(pData);
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| 374 | if (m == NULL)
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| 375 | {
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| 376 | /* error = ENOBUFS; */
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| 377 | error = 1;
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| 378 | goto out;
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| 379 | }
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| 380 | m->m_data += if_maxlinkhdr;
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| 381 | m->m_len = hdrlen;
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| 382 |
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| 383 | /*
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| 384 | * This will always succeed, since we make sure our mbufs
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| 385 | * are big enough to hold one MSS packet + header + ... etc.
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| 386 | */
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| 387 | #if 0
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| 388 | if (len <= MHLEN - hdrlen - max_linkhdr)
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| 389 | {
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| 390 | #endif
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| 391 | sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
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| 392 | m->m_len += len;
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| 393 | #if 0
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| 394 | }
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| 395 | else
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| 396 | {
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| 397 | m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
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| 398 | if (m->m_next == 0)
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| 399 | len = 0;
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| 400 | }
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| 401 | #endif
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| 402 | /*
|
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| 403 | * If we're sending everything we've got, set PUSH.
|
|---|
| 404 | * (This will keep happy those implementations which only
|
|---|
| 405 | * give data to the user when a buffer fills or
|
|---|
| 406 | * a PUSH comes in.)
|
|---|
| 407 | */
|
|---|
| 408 | if (off + len == so->so_snd.sb_cc)
|
|---|
| 409 | flags |= TH_PUSH;
|
|---|
| 410 | }
|
|---|
| 411 | else
|
|---|
| 412 | {
|
|---|
| 413 | if (tp->t_flags & TF_ACKNOW)
|
|---|
| 414 | tcpstat.tcps_sndacks++;
|
|---|
| 415 | else if (flags & (TH_SYN|TH_FIN|TH_RST))
|
|---|
| 416 | tcpstat.tcps_sndctrl++;
|
|---|
| 417 | else if (SEQ_GT(tp->snd_up, tp->snd_una))
|
|---|
| 418 | tcpstat.tcps_sndurg++;
|
|---|
| 419 | else
|
|---|
| 420 | tcpstat.tcps_sndwinup++;
|
|---|
| 421 |
|
|---|
| 422 | m = m_get(pData);
|
|---|
| 423 | if (m == NULL)
|
|---|
| 424 | {
|
|---|
| 425 | /* error = ENOBUFS; */
|
|---|
| 426 | error = 1;
|
|---|
| 427 | goto out;
|
|---|
| 428 | }
|
|---|
| 429 | m->m_data += if_maxlinkhdr;
|
|---|
| 430 | m->m_len = hdrlen;
|
|---|
| 431 | }
|
|---|
| 432 |
|
|---|
| 433 | ti = mtod(m, struct tcpiphdr *);
|
|---|
| 434 |
|
|---|
| 435 | memcpy((caddr_t)ti, &tp->t_template, sizeof (struct tcpiphdr));
|
|---|
| 436 |
|
|---|
| 437 | /*
|
|---|
| 438 | * Fill in fields, remembering maximum advertised
|
|---|
| 439 | * window for use in delaying messages about window sizes.
|
|---|
| 440 | * If resending a FIN, be sure not to use a new sequence number.
|
|---|
| 441 | */
|
|---|
| 442 | if ( flags & TH_FIN
|
|---|
| 443 | && tp->t_flags & TF_SENTFIN
|
|---|
| 444 | && tp->snd_nxt == tp->snd_max)
|
|---|
| 445 | tp->snd_nxt--;
|
|---|
| 446 | /*
|
|---|
| 447 | * If we are doing retransmissions, then snd_nxt will
|
|---|
| 448 | * not reflect the first unsent octet. For ACK only
|
|---|
| 449 | * packets, we do not want the sequence number of the
|
|---|
| 450 | * retransmitted packet, we want the sequence number
|
|---|
| 451 | * of the next unsent octet. So, if there is no data
|
|---|
| 452 | * (and no SYN or FIN), use snd_max instead of snd_nxt
|
|---|
| 453 | * when filling in ti_seq. But if we are in persist
|
|---|
| 454 | * state, snd_max might reflect one byte beyond the
|
|---|
| 455 | * right edge of the window, so use snd_nxt in that
|
|---|
| 456 | * case, since we know we aren't doing a retransmission.
|
|---|
| 457 | * (retransmit and persist are mutually exclusive...)
|
|---|
| 458 | */
|
|---|
| 459 | if (len || (flags & (TH_SYN|TH_FIN)) || tp->t_timer[TCPT_PERSIST])
|
|---|
| 460 | ti->ti_seq = htonl(tp->snd_nxt);
|
|---|
| 461 | else
|
|---|
| 462 | ti->ti_seq = htonl(tp->snd_max);
|
|---|
| 463 | ti->ti_ack = htonl(tp->rcv_nxt);
|
|---|
| 464 | if (optlen)
|
|---|
| 465 | {
|
|---|
| 466 | memcpy((caddr_t)(ti + 1), (caddr_t)opt, optlen);
|
|---|
| 467 | ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2;
|
|---|
| 468 | }
|
|---|
| 469 | ti->ti_flags = flags;
|
|---|
| 470 | /*
|
|---|
| 471 | * Calculate receive window. Don't shrink window,
|
|---|
| 472 | * but avoid silly window syndrome.
|
|---|
| 473 | */
|
|---|
| 474 | if (win < (long)(so->so_rcv.sb_datalen / 4) && win < (long)tp->t_maxseg)
|
|---|
| 475 | win = 0;
|
|---|
| 476 | if (win > (long)TCP_MAXWIN << tp->rcv_scale)
|
|---|
| 477 | win = (long)TCP_MAXWIN << tp->rcv_scale;
|
|---|
| 478 | if (win < (long)(tp->rcv_adv - tp->rcv_nxt))
|
|---|
| 479 | win = (long)(tp->rcv_adv - tp->rcv_nxt);
|
|---|
| 480 | ti->ti_win = htons((u_int16_t) (win>>tp->rcv_scale));
|
|---|
| 481 |
|
|---|
| 482 | #if 0
|
|---|
| 483 | if (SEQ_GT(tp->snd_up, tp->snd_nxt))
|
|---|
| 484 | {
|
|---|
| 485 | ti->ti_urp = htons((u_int16_t)(tp->snd_up - tp->snd_nxt));
|
|---|
| 486 | #else
|
|---|
| 487 | if (SEQ_GT(tp->snd_up, tp->snd_una))
|
|---|
| 488 | {
|
|---|
| 489 | ti->ti_urp = htons((u_int16_t)(tp->snd_up - ntohl(ti->ti_seq)));
|
|---|
| 490 | #endif
|
|---|
| 491 | ti->ti_flags |= TH_URG;
|
|---|
| 492 | }
|
|---|
| 493 | else
|
|---|
| 494 | /*
|
|---|
| 495 | * If no urgent pointer to send, then we pull
|
|---|
| 496 | * the urgent pointer to the left edge of the send window
|
|---|
| 497 | * so that it doesn't drift into the send window on sequence
|
|---|
| 498 | * number wraparound.
|
|---|
| 499 | */
|
|---|
| 500 | tp->snd_up = tp->snd_una; /* drag it along */
|
|---|
| 501 |
|
|---|
| 502 | /*
|
|---|
| 503 | * Put TCP length in extended header, and then
|
|---|
| 504 | * checksum extended header and data.
|
|---|
| 505 | */
|
|---|
| 506 | if (len + optlen)
|
|---|
| 507 | ti->ti_len = htons((u_int16_t)(sizeof (struct tcphdr)
|
|---|
| 508 | + optlen + len));
|
|---|
| 509 | ti->ti_sum = cksum(m, (int)(hdrlen + len));
|
|---|
| 510 |
|
|---|
| 511 | /*
|
|---|
| 512 | * In transmit state, time the transmission and arrange for
|
|---|
| 513 | * the retransmit. In persist state, just set snd_max.
|
|---|
| 514 | */
|
|---|
| 515 | if (tp->t_force == 0 || tp->t_timer[TCPT_PERSIST] == 0)
|
|---|
| 516 | {
|
|---|
| 517 | tcp_seq startseq = tp->snd_nxt;
|
|---|
| 518 |
|
|---|
| 519 | /*
|
|---|
| 520 | * Advance snd_nxt over sequence space of this segment.
|
|---|
| 521 | */
|
|---|
| 522 | if (flags & (TH_SYN|TH_FIN))
|
|---|
| 523 | {
|
|---|
| 524 | if (flags & TH_SYN)
|
|---|
| 525 | tp->snd_nxt++;
|
|---|
| 526 | if (flags & TH_FIN)
|
|---|
| 527 | {
|
|---|
| 528 | tp->snd_nxt++;
|
|---|
| 529 | tp->t_flags |= TF_SENTFIN;
|
|---|
| 530 | }
|
|---|
| 531 | }
|
|---|
| 532 | tp->snd_nxt += len;
|
|---|
| 533 | if (SEQ_GT(tp->snd_nxt, tp->snd_max))
|
|---|
| 534 | {
|
|---|
| 535 | tp->snd_max = tp->snd_nxt;
|
|---|
| 536 | /*
|
|---|
| 537 | * Time this transmission if not a retransmission and
|
|---|
| 538 | * not currently timing anything.
|
|---|
| 539 | */
|
|---|
| 540 | if (tp->t_rtt == 0)
|
|---|
| 541 | {
|
|---|
| 542 | tp->t_rtt = 1;
|
|---|
| 543 | tp->t_rtseq = startseq;
|
|---|
| 544 | tcpstat.tcps_segstimed++;
|
|---|
| 545 | }
|
|---|
| 546 | }
|
|---|
| 547 |
|
|---|
| 548 | /*
|
|---|
| 549 | * Set retransmit timer if not currently set,
|
|---|
| 550 | * and not doing an ack or a keep-alive probe.
|
|---|
| 551 | * Initial value for retransmit timer is smoothed
|
|---|
| 552 | * round-trip time + 2 * round-trip time variance.
|
|---|
| 553 | * Initialize shift counter which is used for backoff
|
|---|
| 554 | * of retransmit time.
|
|---|
| 555 | */
|
|---|
| 556 | if ( tp->t_timer[TCPT_REXMT] == 0
|
|---|
| 557 | && tp->snd_nxt != tp->snd_una)
|
|---|
| 558 | {
|
|---|
| 559 | tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
|
|---|
| 560 | if (tp->t_timer[TCPT_PERSIST])
|
|---|
| 561 | {
|
|---|
| 562 | tp->t_timer[TCPT_PERSIST] = 0;
|
|---|
| 563 | tp->t_rxtshift = 0;
|
|---|
| 564 | }
|
|---|
| 565 | }
|
|---|
| 566 | }
|
|---|
| 567 | else
|
|---|
| 568 | if (SEQ_GT(tp->snd_nxt + len, tp->snd_max))
|
|---|
| 569 | tp->snd_max = tp->snd_nxt + len;
|
|---|
| 570 |
|
|---|
| 571 | /*
|
|---|
| 572 | * Fill in IP length and desired time to live and
|
|---|
| 573 | * send to IP level. There should be a better way
|
|---|
| 574 | * to handle ttl and tos; we could keep them in
|
|---|
| 575 | * the template, but need a way to checksum without them.
|
|---|
| 576 | */
|
|---|
| 577 | m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
|
|---|
| 578 |
|
|---|
| 579 | {
|
|---|
| 580 | ((struct ip *)ti)->ip_len = m->m_len;
|
|---|
| 581 | ((struct ip *)ti)->ip_ttl = ip_defttl;
|
|---|
| 582 | ((struct ip *)ti)->ip_tos = so->so_iptos;
|
|---|
| 583 |
|
|---|
| 584 | /* #if BSD >= 43 */
|
|---|
| 585 | /* Don't do IP options... */
|
|---|
| 586 | #if 0
|
|---|
| 587 | error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route,
|
|---|
| 588 | so->so_options & SO_DONTROUTE, 0);
|
|---|
| 589 | #endif
|
|---|
| 590 | error = ip_output(pData, so, m);
|
|---|
| 591 |
|
|---|
| 592 | #if 0
|
|---|
| 593 | /* #else */
|
|---|
| 594 | error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route,
|
|---|
| 595 | so->so_options & SO_DONTROUTE);
|
|---|
| 596 | /* #endif */
|
|---|
| 597 | #endif
|
|---|
| 598 | }
|
|---|
| 599 | if (error)
|
|---|
| 600 | {
|
|---|
| 601 | out:
|
|---|
| 602 | #if 0
|
|---|
| 603 | if (error == ENOBUFS)
|
|---|
| 604 | {
|
|---|
| 605 | tcp_quench(tp->t_inpcb, 0);
|
|---|
| 606 | return (0);
|
|---|
| 607 | }
|
|---|
| 608 |
|
|---|
| 609 | if ( ( error == EHOSTUNREACH
|
|---|
| 610 | || error == ENETDOWN)
|
|---|
| 611 | && TCPS_HAVERCVDSYN(tp->t_state))
|
|---|
| 612 | {
|
|---|
| 613 | tp->t_softerror = error;
|
|---|
| 614 | return (0);
|
|---|
| 615 | }
|
|---|
| 616 | #endif
|
|---|
| 617 | return (error);
|
|---|
| 618 | }
|
|---|
| 619 | tcpstat.tcps_sndtotal++;
|
|---|
| 620 |
|
|---|
| 621 | /*
|
|---|
| 622 | * Data sent (as far as we can tell).
|
|---|
| 623 | * If this advertises a larger window than any other segment,
|
|---|
| 624 | * then remember the size of the advertised window.
|
|---|
| 625 | * Any pending ACK has now been sent.
|
|---|
| 626 | */
|
|---|
| 627 | if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
|
|---|
| 628 | tp->rcv_adv = tp->rcv_nxt + win;
|
|---|
| 629 | tp->last_ack_sent = tp->rcv_nxt;
|
|---|
| 630 | tp->t_flags &= ~(TF_ACKNOW|TF_DELACK);
|
|---|
| 631 | if (sendalot)
|
|---|
| 632 | goto again;
|
|---|
| 633 |
|
|---|
| 634 | return (0);
|
|---|
| 635 | }
|
|---|
| 636 |
|
|---|
| 637 | void
|
|---|
| 638 | tcp_setpersist(struct tcpcb *tp)
|
|---|
| 639 | {
|
|---|
| 640 | int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
|
|---|
| 641 |
|
|---|
| 642 | #if 0
|
|---|
| 643 | if (tp->t_timer[TCPT_REXMT])
|
|---|
| 644 | panic("tcp_output REXMT");
|
|---|
| 645 | #endif
|
|---|
| 646 | /*
|
|---|
| 647 | * Start/restart persistence timer.
|
|---|
| 648 | */
|
|---|
| 649 | TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
|
|---|
| 650 | t * tcp_backoff[tp->t_rxtshift],
|
|---|
| 651 | TCPTV_PERSMIN, TCPTV_PERSMAX);
|
|---|
| 652 | if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
|
|---|
| 653 | tp->t_rxtshift++;
|
|---|
| 654 | }
|
|---|
