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1 /* |
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2 * Copyright (c) 1982, 1986, 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_timer.h 8.1 (Berkeley) 6/10/93 |
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34 * tcp_timer.h,v 1.4 1994/08/21 05:27:38 paul Exp |
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35 */ |
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36 |
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37 #ifndef _TCP_TIMER_H_ |
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38 #define _TCP_TIMER_H_ |
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39 |
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40 /* |
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41 * Definitions of the TCP timers. These timers are counted |
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42 * down PR_SLOWHZ times a second. |
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43 */ |
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44 #define TCPT_NTIMERS 4 |
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45 |
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46 #define TCPT_REXMT 0 /* retransmit */ |
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47 #define TCPT_PERSIST 1 /* retransmit persistence */ |
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48 #define TCPT_KEEP 2 /* keep alive */ |
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49 #define TCPT_2MSL 3 /* 2*msl quiet time timer */ |
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50 |
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51 /* |
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52 * The TCPT_REXMT timer is used to force retransmissions. |
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53 * The TCP has the TCPT_REXMT timer set whenever segments |
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54 * have been sent for which ACKs are expected but not yet |
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55 * received. If an ACK is received which advances tp->snd_una, |
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56 * then the retransmit timer is cleared (if there are no more |
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57 * outstanding segments) or reset to the base value (if there |
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58 * are more ACKs expected). Whenever the retransmit timer goes off, |
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59 * we retransmit one unacknowledged segment, and do a backoff |
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60 * on the retransmit timer. |
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61 * |
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62 * The TCPT_PERSIST timer is used to keep window size information |
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63 * flowing even if the window goes shut. If all previous transmissions |
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64 * have been acknowledged (so that there are no retransmissions in progress), |
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65 * and the window is too small to bother sending anything, then we start |
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66 * the TCPT_PERSIST timer. When it expires, if the window is nonzero, |
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67 * we go to transmit state. Otherwise, at intervals send a single byte |
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68 * into the peer's window to force him to update our window information. |
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69 * We do this at most as often as TCPT_PERSMIN time intervals, |
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70 * but no more frequently than the current estimate of round-trip |
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71 * packet time. The TCPT_PERSIST timer is cleared whenever we receive |
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72 * a window update from the peer. |
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73 * |
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74 * The TCPT_KEEP timer is used to keep connections alive. If an |
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75 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, |
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76 * but not yet established, then we drop the connection. Once the connection |
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77 * is established, if the connection is idle for TCPTV_KEEP_IDLE time |
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78 * (and keepalives have been enabled on the socket), we begin to probe |
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79 * the connection. We force the peer to send us a segment by sending: |
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80 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> |
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81 * This segment is (deliberately) outside the window, and should elicit |
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82 * an ack segment in response from the peer. If, despite the TCPT_KEEP |
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83 * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE |
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84 * amount of time probing, then we drop the connection. |
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85 */ |
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86 |
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87 /* |
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88 * Time constants. |
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89 */ |
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90 #define TCPTV_MSL ( 5*PR_SLOWHZ) /* max seg lifetime (hah!) */ |
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91 |
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92 #define TCPTV_SRTTBASE 0 /* base roundtrip time; |
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93 if 0, no idea yet */ |
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94 #define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ |
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95 |
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96 #define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */ |
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97 #define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ |
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98 |
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99 #define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */ |
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100 #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */ |
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101 #define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */ |
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102 #define TCPTV_KEEPCNT 8 /* max probes before drop */ |
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103 |
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104 #define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ |
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105 /* #define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) */ /* max allowable REXMT value */ |
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106 #define TCPTV_REXMTMAX ( 12*PR_SLOWHZ) /* max allowable REXMT value */ |
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107 |
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108 #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ |
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109 |
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110 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ |
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111 |
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112 |
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113 #ifdef TCPTIMERS |
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114 char *tcptimers[] = |
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115 { "REXMT", "PERSIST", "KEEP", "2MSL" }; |
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116 #endif |
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117 |
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118 /* |
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119 * Force a time value to be in a certain range. |
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120 */ |
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121 #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ |
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122 (tv) = (value); \ |
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123 if ((tv) < (tvmin)) \ |
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124 (tv) = (tvmin); \ |
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125 else if ((tv) > (tvmax)) \ |
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126 (tv) = (tvmax); \ |
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127 } |
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128 |
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129 extern const int tcp_backoff[]; |
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130 |
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131 struct tcpcb; |
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132 |
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133 void tcp_fasttimo _P((void)); |
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134 void tcp_slowtimo _P((void)); |
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135 void tcp_canceltimers _P((struct tcpcb *)); |
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136 |
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137 #endif |