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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 BSD_KERNEL_PRIVATE 69 #include <kern/thread_call.h> 70 #endif /* BSD_KERNEL_PRIVATE */ 71 72 /* Keep the external definition the same for binary compatibility */ 73 #define TCPT_NTIMERS_EXT 4 74 75 /* 76 * Definitions of the TCP timers. 77 * 78 * The TCPT_PTO timer is used for probing for a tail loss in a send window. 79 * If this probe gets acknowledged using SACK, it will allow the connection 80 * to enter fast-recovery instead of hitting a retransmit timeout. A probe 81 * timeout will send the last unacknowledged segment to generate more acks 82 * with SACK information which can be used for fast-retransmiting the lost 83 * packets. This will fire in the order of 10ms. 84 * 85 * The TCPT_REXMT timer is used to force retransmissions. 86 * The TCP has the TCPT_REXMT timer set whenever segments 87 * have been sent for which ACKs are expected but not yet 88 * received. If an ACK is received which advances tp->snd_una, 89 * then the retransmit timer is cleared (if there are no more 90 * outstanding segments) or reset to the base value (if there 91 * are more ACKs expected). Whenever the retransmit timer goes off, 92 * we retransmit one unacknowledged segment, and do a backoff 93 * on the retransmit timer. 94 * 95 * The TCPT_DELACK timer is used for transmitting delayed acknowledgements 96 * if an acknowledgement was delayed in anticipation of a new segment. 97 * 98 * The TCPT_PERSIST timer is used to keep window size information 99 * flowing even if the window goes shut. If all previous transmissions 100 * have been acknowledged(so that there are no retransmissions in progress), 101 * and the window is too small to bother sending anything, then we start 102 * the TCPT_PERSIST timer. When it expires, if the window is nonzero, 103 * we go to transmit state. Otherwise, at intervals send a single byte 104 * into the peer's window to force him to update our window information. 105 * We do this at most as often as TCPT_PERSMIN time intervals, 106 * but no more frequently than the current estimate of round-trip 107 * packet time. The TCPT_PERSIST timer is cleared whenever we receive 108 * a window update from the peer. 109 * 110 * The TCPT_KEEP timer is used to keep connections alive. If an 111 * connection is idle (no segments received) for TCPTV_KEEP_INIT amount 112 * of time, but not yet established, then we drop the connection. 113 * Once the connection is established, if the connection is idle for 114 * TCPTV_KEEP_IDLE time (and keepalives have been enabled on the socket), 115 * we begin to probe the connection. We force the peer to send us a 116 * 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 121 * TCPT_MAXIDLE amount of time probing, then we drop the connection. 122 * 123 * The TCPT_2MSL timer is used for keeping the conenction in Time-wait state 124 * before fully closing it so that the connection 4-tuple can be reused. 125 */ 126 #ifdef BSD_KERNEL_PRIVATE 127 128 #define TCPT_PTO 0 /* Probe timeout */ 129 #define TCPT_DELAYFR 1 /* Delay recovery if there is reordering */ 130 #define TCPT_REORDER 2 /* Reordering timer for RACK */ 131 #define TCPT_REXMT 3 /* retransmit */ 132 #define TCPT_DELACK 4 /* delayed ack */ 133 #define TCPT_PERSIST 5 /* retransmit persistence */ 134 #define TCPT_KEEP 6 /* keep alive */ 135 #define TCPT_2MSL 7 /* 2*msl quiet time timer */ 136 #if MPTCP 137 #define TCPT_JACK_RXMT 8 /* retransmit timer for join ack */ 138 #define TCPT_CELLICON 9 /* Timer to check for cell-activity */ 139 #define TCPT_MAX 9 140 #else /* MPTCP */ 141 #define TCPT_MAX 7 142 #endif /* !MPTCP */ 143 144 #define TCPT_NONE (TCPT_MAX + 1) 145 #define TCPT_NTIMERS (TCPT_MAX + 1) 146 147 /* External definitions */ 148 #define TCPT_REXMT_EXT 0 149 #define TCPT_PERSIST_EXT 1 150 #define TCPT_KEEP_EXT 2 151 #define TCPT_2MSL_EXT 3 152 #define TCPT_DELACK_EXT 4 153 154 #else /* !BSD_KERNEL_PRIVATE */ 155 #define TCPT_REXMT 0 /* retransmit */ 156 #define TCPT_PERSIST 1 /* retransmit persistence */ 157 #define TCPT_KEEP 2 /* keep alive */ 158 #define TCPT_2MSL 3 /* 2*msl quiet time timer */ 159 #define TCPT_DELACK 4 /* delayed ack timer */ 160 #if MPTCP 161 #define TCPT_JACK_RXMT 5 /* retransmit timer for join ack */ 162 #define TCPT_MAX 5 163 #else /* MPTCP */ 164 #define TCPT_MAX 4 165 #endif /* !MPTCP */ 166 #define TCPT_NONE (TCPT_MAX + 1) 167 #define TCPT_NTIMERS (TCPT_MAX + 1) 168 169 #endif /* BSD_KERNEL_PRIVATE */ 170 171 #ifdef BSD_KERNEL_PRIVATE 172 /* 173 * Time constants. 174 */ 175 #define TCPTV_MSL ( 15*TCP_RETRANSHZ) /* max seg lifetime */ 176 #define TCPTV_SRTTBASE 0 /* base roundtrip time; if 0, no idea yet */ 177 #define TCPTV_RTOBASE ( 1*TCP_RETRANSHZ) /* assumed RTO if no info */ 178 #define TCPTV_SRTTDFLT ( 1*TCP_RETRANSHZ) /* assumed RTT if no info */ 179 #define TCPTV_PERSMIN ( 5*TCP_RETRANSHZ) /* retransmit persistence */ 180 #define TCPTV_PERSMAX ( 60*TCP_RETRANSHZ) /* maximum persist interval */ 181 182 extern int tcptv_persmin_val; 183 184 #define TCPTV_KEEP_INIT ( 75*TCP_RETRANSHZ) /* connect keep alive */ 185 #define TCPTV_KEEP_IDLE (120*60*TCP_RETRANSHZ) /* time before probing */ 186 #define TCPTV_KEEPINTVL ( 75*TCP_RETRANSHZ) /* default probe interval */ 187 #define TCPTV_KEEPCNT 8 /* max probes before drop */ 188 189 #define TCPTV_REXMTMAX ( 64*TCP_RETRANSHZ ) /* max REXMT value */ 190 #define TCPTV_REXMTMIN ( TCP_RETRANSHZ/33 ) /* min REXMT for non-local connections */ 191 192 #define TCPTV_FINWAIT2 ( 60*TCP_RETRANSHZ) /* timeout to get out of FIN_WAIT_2 */ 193 194 #define TCPTV_TWTRUNC 8 /* RTO factor to truncate TW */ 195 196 #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ 197 198 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ 199 200 #ifdef TCPTIMERS 201 static char *tcptimers[] = 202 { "REXMT", "PERSIST", "KEEP", "2MSL", "DELACK"}; 203 #endif /* TCPTIMERS */ 204 205 /* 206 * Persist, keep, 2msl and MPTCP's join-ack timer as slow timers which can 207 * be coalesced at a higher granularity (500 ms). 208 * 209 * Rexmt and delayed ack timers are considered as fast timers which run 210 * in the order of 100ms. 211 * 212 * Probe timeout and RACK reordering timer are quick timers which will run in the order of 10ms. 213 */ 214 #define IS_TIMER_HZ_500MS(i) ((i) >= TCPT_PERSIST) 215 #define IS_TIMER_HZ_100MS(i) ((i) >= TCPT_REXMT && (i) < TCPT_PERSIST) 216 #define IS_TIMER_HZ_10MS(i) ((i) < TCPT_REXMT) 217 218 struct tcptimerlist; 219 220 struct tcptimerentry { 221 LIST_ENTRY(tcptimerentry) te_le; /* links for timer list */ 222 uint32_t te_timer_start; /* tcp clock when the timer was started */ 223 uint16_t te_index; /* index of lowest timer that needs to run first */ 224 uint16_t te_mode; /* Bit-wise OR of timers that are active */ 225 uint32_t te_runtime; /* deadline at which the first timer has to fire */ 226 }; 227 228 LIST_HEAD(timerlisthead, tcptimerentry); 229 230 struct tcptimerlist { 231 struct timerlisthead lhead; /* head of the list */ 232 lck_mtx_t mtx; /* lock to protect the list */ 233 lck_grp_t *mtx_grp; /* mutex group definition */ 234 thread_call_t call; /* call entry */ 235 uint32_t runtime; /* time at which this list is going to run */ 236 uint32_t schedtime; /* time at which this list was scheduled */ 237 uint32_t started_at; /* time at which this list started to run */ 238 uint32_t entries; /* Number of entries on the list */ 239 uint32_t maxentries; /* Max number of entries at any time */ 240 uint32_t processed_count; /* Number of entries that have been processed */ 241 242 /* Set desired mode when timer list running */ 243 boolean_t running; /* Set when timer list is being processed */ 244 boolean_t scheduled; /* set when the timer is scheduled */ 245 #define TCP_TIMERLIST_10MS_MODE 0x1 246 #define TCP_TIMERLIST_100MS_MODE 0x2 247 #define TCP_TIMERLIST_500MS_MODE 0x4 248 uint32_t mode; /* Current mode of the timer */ 249 uint32_t pref_mode; /* Preferred mode set by a connection */ 250 uint32_t pref_offset; /* Preferred offset set by a connection */ 251 uint32_t idleruns; /* Number of times the list has been idle in fast mode */ 252 struct tcptimerentry *next_te; /* next timer entry pointer to process */ 253 u_int16_t probe_if_index; /* Interface index that needs to send probes */ 254 }; 255 256 /* number of idle runs allowed for TCP timer list in fast or quick modes */ 257 #define TCP_FASTMODE_IDLERUN_MAX 10 258 259 /* 260 * Minimum retransmit timeout is set to 30ms. We add a slop of 261 * 200 ms to the retransmit value to account for processing 262 * variance and delayed ack. This extra 200ms will help to avoid 263 * spurious retransmits by taking into consideration the receivers 264 * that wait for delayed ack timer instead of generating an ack 265 * for every two packets. 266 * 267 * On a local link, the minimum retransmit timeout is 100ms and 268 * variance is set to 0. This will make the sender a little bit more 269 * aggressive on local link. When the connection is not established yet, 270 * there is no need to add an extra 200ms to retransmit timeout because 271 * the initial value is high (1s) and delayed ack is not a problem in 272 * that case. 273 */ 274 #define TCPTV_REXMTSLOP ( TCP_RETRANSHZ/5 ) /* extra 200 ms slop */ 275 276 /* macro to decide when retransmit slop (described above) should be added */ 277 #define TCP_ADD_REXMTSLOP(tp) (tp->t_state >= TCPS_ESTABLISHED) 278 279 #define TCPT_RANGESET(tv, value, tvmin, tvmax, addslop) do { \ 280 (tv) = ((addslop) ? tcp_rexmt_slop : 0) + (value); \ 281 if ((uint32_t)(tv) < (uint32_t)(tvmin)) \ 282 (tv) = (tvmin); \ 283 else if ((uint32_t)(tv) > (uint32_t)(tvmax)) \ 284 (tv) = (tvmax); \ 285 } while(0) 286 287 #define TCP_CONN_KEEPIDLE(tp) \ 288 ((tp)->t_keepidle && \ 289 ((tp)->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ? \ 290 (tp)->t_keepidle : (uint32_t)tcp_keepidle) 291 #define TCP_CONN_KEEPINIT(tp) \ 292 (((tp)->t_keepinit > 0) ? (tp)->t_keepinit : (uint32_t)tcp_keepinit) 293 #define TCP_CONN_KEEPCNT(tp) \ 294 (((tp)->t_keepcnt > 0) ? (tp)->t_keepcnt : (uint32_t)tcp_keepcnt) 295 #define TCP_CONN_KEEPINTVL(tp) \ 296 (((tp)->t_keepintvl > 0) ? (tp)->t_keepintvl : (uint32_t)tcp_keepintvl) 297 #define TCP_CONN_MAXIDLE(tp) \ 298 (TCP_CONN_KEEPCNT(tp) * TCP_CONN_KEEPINTVL(tp)) 299 300 #define TCP_IDLETIMEOUT(tp) \ 301 (((TCP_ADD_REXMTSLOP(tp)) ? 0 : tcp_rexmt_slop) + tp->t_rxtcur) 302 303 TAILQ_HEAD(tcptailq, tcpcb); 304 305 extern int tcp_keepinit; /* time to establish connection */ 306 extern int tcp_keepidle; /* time before keepalive probes begin */ 307 extern int tcp_keepintvl; /* time between keepalive probes */ 308 extern int tcp_keepcnt; /* number of keepalives */ 309 extern int tcp_delack; /* delayed ack timer */ 310 extern int tcp_maxpersistidle; 311 extern int tcp_msl; 312 extern int tcp_ttl; /* time to live for TCP segs */ 313 extern int tcp_backoff[TCP_MAXRXTSHIFT + 1]; 314 extern int tcp_rexmt_slop; 315 extern u_int32_t tcp_max_persist_timeout; /* Maximum persistence for Zero Window Probes */ 316 317 #endif /* BSD_KERNEL_PRIVATE */ 318 #endif /* !_NETINET_TCP_TIMER_H_ */ 319