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All rights reserved. 31 * 32 * Redistribution and use in source and binary forms, with or without 33 * modification, are permitted provided that the following conditions 34 * are met: 35 * 1. Redistributions of source code must retain the above copyright 36 * notice, this list of conditions and the following disclaimer. 37 * 2. Redistributions in binary form must reproduce the above copyright 38 * notice, this list of conditions and the following disclaimer in the 39 * documentation and/or other materials provided with the distribution. 40 * 3. All advertising materials mentioning features or use of this software 41 * must display the following acknowledgement: 42 * This product includes software developed by the University of 43 * California, Berkeley and its contributors. 44 * 4. Neither the name of the University nor the names of its contributors 45 * may be used to endorse or promote products derived from this software 46 * without specific prior written permission. 47 * 48 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 51 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 56 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 57 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 58 * SUCH DAMAGE. 59 * 60 * @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93 61 * $FreeBSD: src/sys/netinet/tcp_timer.h,v 1.18 1999/12/29 04:41:03 peter Exp $ 62 */ 63 64#ifndef _NETINET_TCP_TIMER_H_ 65#define _NETINET_TCP_TIMER_H_ 66#include <sys/appleapiopts.h> 67 68#ifdef KERNEL 69#include <kern/thread_call.h> 70#endif /* KERNEL */ 71 72/* 73 * Definitions of the TCP timers. 74 */ 75#define TCPT_NTIMERS 5 76 77/* Keep the external definition the same for binary compatibility */ 78#define TCPT_NTIMERS_EXT 4 79 80#define TCPT_REXMT 0 /* retransmit */ 81#define TCPT_PERSIST 1 /* retransmit persistence */ 82#define TCPT_KEEP 2 /* keep alive */ 83#define TCPT_2MSL 3 /* 2*msl quiet time timer */ 84#define TCPT_DELACK 4 /* delayed ack timer */ 85#define TCPT_MAX 4 86#define TCPT_NONE (TCPT_MAX + 1) 87 88/* 89 * The TCPT_REXMT timer is used to force retransmissions. 90 * The TCP has the TCPT_REXMT timer set whenever segments 91 * have been sent for which ACKs are expected but not yet 92 * received. If an ACK is received which advances tp->snd_una, 93 * then the retransmit timer is cleared (if there are no more 94 * outstanding segments) or reset to the base value (if there 95 * are more ACKs expected). Whenever the retransmit timer goes off, 96 * we retransmit one unacknowledged segment, and do a backoff 97 * on the retransmit timer. 98 * 99 * The TCPT_PERSIST timer is used to keep window size information 100 * flowing even if the window goes shut. If all previous transmissions 101 * have been acknowledged (so that there are no retransmissions in progress), 102 * and the window is too small to bother sending anything, then we start 103 * the TCPT_PERSIST timer. When it expires, if the window is nonzero, 104 * we go to transmit state. Otherwise, at intervals send a single byte 105 * into the peer's window to force him to update our window information. 106 * We do this at most as often as TCPT_PERSMIN time intervals, 107 * but no more frequently than the current estimate of round-trip 108 * packet time. The TCPT_PERSIST timer is cleared whenever we receive 109 * a window update from the peer. 110 * 111 * The TCPT_KEEP timer is used to keep connections alive. If an 112 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, 113 * but not yet established, then we drop the connection. Once the connection 114 * is established, if the connection is idle for TCPTV_KEEP_IDLE time 115 * (and keepalives have been enabled on the socket), we begin to probe 116 * the connection. We force the peer to send us a segment by sending: 117 * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> 118 * This segment is (deliberately) outside the window, and should elicit 119 * an ack segment in response from the peer. If, despite the TCPT_KEEP 120 * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE 121 * amount of time probing, then we drop the connection. 122 */ 123 124#ifdef PRIVATE 125 126/* 127 * Time constants. 128 */ 129#define TCPTV_MSL ( 15*TCP_RETRANSHZ) /* max seg lifetime (hah!) */ 130#define TCPTV_SRTTBASE 0 /* base roundtrip time; 131 if 0, no idea yet */ 132#define TCPTV_RTOBASE ( 1*TCP_RETRANSHZ) /* assumed RTO if no info */ 133#define TCPTV_SRTTDFLT ( 1*TCP_RETRANSHZ) /* assumed RTT if no info */ 134 135#define TCPTV_PERSMIN ( 5*TCP_RETRANSHZ) /* retransmit persistence */ 136#define TCPTV_PERSMAX ( 60*TCP_RETRANSHZ) /* maximum persist interval */ 137 138#define TCPTV_KEEP_INIT ( 75*TCP_RETRANSHZ) /* initial connect keep alive */ 139#define TCPTV_KEEP_IDLE (120*60*TCP_RETRANSHZ) /* dflt time before probing */ 140#define TCPTV_KEEPINTVL ( 75*TCP_RETRANSHZ) /* default probe interval */ 141#define TCPTV_KEEPCNT 8 /* max probes before drop */ 142 143#define TCPTV_REXMTMAX ( 64*TCP_RETRANSHZ ) /* max allowable REXMT value */ 144#define TCPTV_REXMTMIN ( TCP_RETRANSHZ/33 ) /* min REXMT for non-local connections */ 145#define TCPTV_UNACKWIN ( TCP_RETRANSHZ/10 ) /* Window for counting rcv bytes to see if 146 ack-stretching can start (default 100 ms) */ 147#define TCPTV_MAXRCVIDLE (TCP_RETRANSHZ/5 ) /* Receiver idle time, avoid ack-stretching after that*/ 148#define TCPTV_RCVBUFIDLE (TCP_RETRANSHZ/2) /* Receiver idle time, for rcv socket buffer resizing */ 149 150/* No ack stretching during slow-start, until we see some packets. 151 * By the time the receiver gets 512 packets, the senders cwnd 152 * should open by a few hundred packets consdering the 153 * slow-start progression. 154 */ 155#define TCP_RCV_SS_PKTCOUNT 512 156 157#define TCPTV_TWTRUNC 8 /* RTO factor to truncate TW */ 158 159#define TCP_LINGERTIME 120 /* linger at most 2 minutes */ 160 161#define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ 162 163#ifdef TCPTIMERS 164static char *tcptimers[] = 165 { "REXMT", "PERSIST", "KEEP", "2MSL" , "DELACK"}; 166#endif 167 168#ifdef KERNEL 169 170/* We consider persist, keep and 2msl as slow timers which can be coalesced 171 * at a higher granularity (500 ms). Rexmt and delayed ack are considered fast 172 * timers which fire in the order of 100ms. 173 * 174 * The following conditional is to check if a timer is one of the slow timers. This 175 * is fast and works well for now. If we add more slow timers for any reason, 176 * we may need to change this. 177 */ 178#define IS_TIMER_SLOW(ind) ((ind & 0x3) != 0) 179 180struct tcptimerlist; 181 182struct tcptimerentry { 183 LIST_ENTRY(tcptimerentry) le; /* links for timer list */ 184 uint32_t timer_start; /* tcp clock when the timer was started */ 185 uint16_t index; /* index of lowest timer that needs to run first */ 186 uint32_t runtime; /* deadline at which the first timer has to fire */ 187}; 188 189LIST_HEAD(timerlisthead, tcptimerentry); 190 191struct tcptimerlist { 192 struct timerlisthead lhead; /* head of the list of timer entries */ 193 lck_mtx_t *mtx; /* lock to protect the list */ 194 lck_attr_t *mtx_attr; /* mutex attributes */ 195 lck_grp_t *mtx_grp; /* mutex group definition */ 196 lck_grp_attr_t *mtx_grp_attr; /* mutex group attributes */ 197 uint32_t fast_quantum; /* minimum time quantum to coalesce fast timers */ 198 uint32_t slow_quantum; /* minimum time quantum to coalesce slow timers */ 199 thread_call_t call; /* call entry */ 200 uint32_t runtime; /* time at which this list is going to run */ 201 uint32_t entries; /* Number of entries on the list */ 202 uint32_t maxentries; /* Max number of entries at any time */ 203 204 /* Set desired mode when timer list running */ 205 boolean_t running; /* Set when timer list is being processed */ 206#define TCP_TIMERLIST_FASTMODE 0x1 207#define TCP_TIMERLIST_SLOWMODE 0x2 208 uint32_t mode; /* Current mode, fast or slow */ 209 uint32_t pref_mode; /* Preferred mode set by a connection, fast or slow */ 210 uint32_t pref_offset; /* Preferred offset set by a connection */ 211 uint32_t idlegen; /* Number of times the list has been idle in fast mode */ 212 struct tcptimerentry *next_te; /* Store the next timer entry pointer to process */ 213 214}; 215 216#define TCP_FASTMODE_IDLEGEN_MAX 20 /* Approximately 2 seconds */ 217 218/* 219 * Minimum retransmit timeout is set to 30ms. We add a slop of 220 * 200 ms to the retransmit value to account for processing 221 * variance and delayed ack. This extra 200ms will help to avoid 222 * spurious retransmits by taking into consideration the receivers 223 * that wait for delayed ack timer instead of generating an ack 224 * for every two packets. 225 * 226 * On a local link, the minimum retransmit timeout is 100ms and 227 * variance is set to 0. This will make the sender a little bit more 228 * aggressive on local link. When the connection is not established yet, 229 * there is no need to add an extra 200ms to retransmit timeout because 230 * the initial value is high (1s) and delayed ack is not a problem in 231 * that case. 232 */ 233#define TCPTV_REXMTSLOP ( TCP_RETRANSHZ/5 ) /* rexmt slop allowed (200 ms) */ 234 235/* macro to decide when retransmit slop (described above) should be added */ 236#define TCP_ADD_REXMTSLOP(tp) (tp->t_state >= TCPS_ESTABLISHED) 237 238#define TCPT_RANGESET(tv, value, tvmin, tvmax, addslop) do { \ 239 (tv) = ((addslop) ? tcp_rexmt_slop : 0) + (value); \ 240 if ((uint32_t)(tv) < (uint32_t)(tvmin)) \ 241 (tv) = (tvmin); \ 242 else if ((uint32_t)(tv) > (uint32_t)(tvmax)) \ 243 (tv) = (tvmax); \ 244} while(0) 245 246#define TCP_KEEPIDLE(tp) \ 247 (tp->t_keepidle && (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ? \ 248 tp->t_keepidle : tcp_keepidle) 249 250/* Since we did not add rexmt slop for local connections, we should add 251 * it to idle timeout. Otherwise local connections will reach idle state 252 * quickly 253 */ 254#define TCP_IDLETIMEOUT(tp) \ 255 (((TCP_ADD_REXMTSLOP(tp)) ? 0 : tcp_rexmt_slop) + tp->t_rxtcur) 256 257extern int tcp_keepinit; /* time to establish connection */ 258extern int tcp_keepidle; /* time before keepalive probes begin */ 259extern int tcp_keepintvl; /* time between keepalive probes */ 260extern int tcp_maxidle; /* time to drop after starting probes */ 261extern int tcp_delack; /* delayed ack timer */ 262extern int tcp_maxpersistidle; 263extern int tcp_msl; 264extern int tcp_ttl; /* time to live for TCP segs */ 265extern int tcp_backoff[]; 266extern int tcp_rexmt_slop; 267extern u_int32_t tcp_max_persist_timeout; /* Maximum persistence for Zero Window Probes */ 268 269#define OFFSET_FROM_START(tp, off) ((tcp_now + (off)) - (tp)->tentry.timer_start) 270 271#endif /* KERNEL */ 272#endif /* PRIVATE */ 273#endif /* !_NETINET_TCP_TIMER_H_ */ 274 275