tcp_timer.h
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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_REXMT 2 /* retransmit */ 131 #define TCPT_DELACK 3 /* delayed ack */ 132 #define TCPT_PERSIST 4 /* retransmit persistence */ 133 #define TCPT_KEEP 5 /* keep alive */ 134 #define TCPT_2MSL 6 /* 2*msl quiet time timer */ 135 #if MPTCP 136 #define TCPT_JACK_RXMT 7 /* retransmit timer for join ack */ 137 #define TCPT_CELLICON 8 /* Timer to check for cell-activity */ 138 #define TCPT_MAX 8 139 #else /* MPTCP */ 140 #define TCPT_MAX 6 141 #endif /* !MPTCP */ 142 143 #define TCPT_NONE (TCPT_MAX + 1) 144 #define TCPT_NTIMERS (TCPT_MAX + 1) 145 146 /* External definitions */ 147 #define TCPT_REXMT_EXT 0 148 #define TCPT_PERSIST_EXT 1 149 #define TCPT_KEEP_EXT 2 150 #define TCPT_2MSL_EXT 3 151 #define TCPT_DELACK_EXT 4 152 153 #else /* !BSD_KERNEL_PRIVATE */ 154 #define TCPT_REXMT 0 /* retransmit */ 155 #define TCPT_PERSIST 1 /* retransmit persistence */ 156 #define TCPT_KEEP 2 /* keep alive */ 157 #define TCPT_2MSL 3 /* 2*msl quiet time timer */ 158 #define TCPT_DELACK 4 /* delayed ack timer */ 159 #if MPTCP 160 #define TCPT_JACK_RXMT 5 /* retransmit timer for join ack */ 161 #define TCPT_MAX 5 162 #else /* MPTCP */ 163 #define TCPT_MAX 4 164 #endif /* !MPTCP */ 165 #define TCPT_NONE (TCPT_MAX + 1) 166 #define TCPT_NTIMERS (TCPT_MAX + 1) 167 168 #endif /* BSD_KERNEL_PRIVATE */ 169 170 #ifdef BSD_KERNEL_PRIVATE 171 /* 172 * Time constants. 173 */ 174 #define TCPTV_MSL ( 15*TCP_RETRANSHZ) /* max seg lifetime */ 175 #define TCPTV_SRTTBASE 0 /* base roundtrip time; if 0, no idea yet */ 176 #define TCPTV_RTOBASE ( 1*TCP_RETRANSHZ) /* assumed RTO if no info */ 177 #define TCPTV_SRTTDFLT ( 1*TCP_RETRANSHZ) /* assumed RTT if no info */ 178 #define TCPTV_PERSMIN ( 5*TCP_RETRANSHZ) /* retransmit persistence */ 179 #define TCPTV_PERSMAX ( 60*TCP_RETRANSHZ) /* maximum persist interval */ 180 181 extern int tcptv_persmin_val; 182 183 #define TCPTV_KEEP_INIT ( 75*TCP_RETRANSHZ) /* connect keep alive */ 184 #define TCPTV_KEEP_IDLE (120*60*TCP_RETRANSHZ) /* time before probing */ 185 #define TCPTV_KEEPINTVL ( 75*TCP_RETRANSHZ) /* default probe interval */ 186 #define TCPTV_KEEPCNT 8 /* max probes before drop */ 187 188 #define TCPTV_REXMTMAX ( 64*TCP_RETRANSHZ ) /* max REXMT value */ 189 #define TCPTV_REXMTMIN ( TCP_RETRANSHZ/33 ) /* min REXMT for non-local connections */ 190 191 /* 192 * Window for counting received bytes to see if ack-stretching 193 * can start (default 100 ms) 194 */ 195 #define TCPTV_UNACKWIN ( TCP_RETRANSHZ/10 ) 196 197 /* Receiver idle time, avoid ack-stretching after this idle time */ 198 #define TCPTV_MAXRCVIDLE (TCP_RETRANSHZ/5 ) 199 200 /* 201 * No ack stretching during slow-start, until we see some packets. 202 * By the time the receiver gets 512 packets, the senders cwnd 203 * should open by a few hundred packets consdering the 204 * slow-start progression. 205 */ 206 #define TCP_RCV_SS_PKTCOUNT 512 207 208 #define TCPTV_TWTRUNC 8 /* RTO factor to truncate TW */ 209 210 #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ 211 212 #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ 213 214 #ifdef TCPTIMERS 215 static char *tcptimers[] = 216 { "REXMT", "PERSIST", "KEEP", "2MSL", "DELACK"}; 217 #endif /* TCPTIMERS */ 218 219 /* 220 * Persist, keep, 2msl and MPTCP's join-ack timer as slow timers which can 221 * be coalesced at a higher granularity (500 ms). 222 * 223 * Rexmt and delayed ack timers are considered as fast timers which run 224 * in the order of 100ms. 225 * 226 * Probe timeout is a quick timer which will run in the order of 10ms. 227 */ 228 #define IS_TIMER_HZ_500MS(i) ((i) >= TCPT_PERSIST) 229 #define IS_TIMER_HZ_100MS(i) ((i) >= TCPT_REXMT && (i) < TCPT_PERSIST) 230 #define IS_TIMER_HZ_10MS(i) ((i) < TCPT_REXMT) 231 232 struct tcptimerlist; 233 234 struct tcptimerentry { 235 LIST_ENTRY(tcptimerentry) le; /* links for timer list */ 236 uint32_t timer_start; /* tcp clock when the timer was started */ 237 uint16_t index; /* index of lowest timer that needs to run first */ 238 uint16_t mode; /* Bit-wise OR of timers that are active */ 239 uint32_t runtime; /* deadline at which the first timer has to fire */ 240 }; 241 242 LIST_HEAD(timerlisthead, tcptimerentry); 243 244 struct tcptimerlist { 245 struct timerlisthead lhead; /* head of the list */ 246 lck_mtx_t *mtx; /* lock to protect the list */ 247 lck_attr_t *mtx_attr; /* mutex attributes */ 248 lck_grp_t *mtx_grp; /* mutex group definition */ 249 lck_grp_attr_t *mtx_grp_attr; /* mutex group attributes */ 250 thread_call_t call; /* call entry */ 251 uint32_t runtime; /* time at which this list is going to run */ 252 uint32_t schedtime; /* time at which this list was scheduled */ 253 uint32_t entries; /* Number of entries on the list */ 254 uint32_t maxentries; /* Max number of entries at any time */ 255 256 /* Set desired mode when timer list running */ 257 boolean_t running; /* Set when timer list is being processed */ 258 boolean_t scheduled; /* set when the timer is scheduled */ 259 #define TCP_TIMERLIST_10MS_MODE 0x1 260 #define TCP_TIMERLIST_100MS_MODE 0x2 261 #define TCP_TIMERLIST_500MS_MODE 0x4 262 uint32_t mode; /* Current mode of the timer */ 263 uint32_t pref_mode; /* Preferred mode set by a connection */ 264 uint32_t pref_offset; /* Preferred offset set by a connection */ 265 uint32_t idleruns; /* Number of times the list has been idle in fast mode */ 266 struct tcptimerentry *next_te; /* next timer entry pointer to process */ 267 u_int16_t probe_if_index; /* Interface index that needs to send probes */ 268 }; 269 270 /* number of idle runs allowed for TCP timer list in fast or quick modes */ 271 #define TCP_FASTMODE_IDLERUN_MAX 10 272 273 /* 274 * Minimum retransmit timeout is set to 30ms. We add a slop of 275 * 200 ms to the retransmit value to account for processing 276 * variance and delayed ack. This extra 200ms will help to avoid 277 * spurious retransmits by taking into consideration the receivers 278 * that wait for delayed ack timer instead of generating an ack 279 * for every two packets. 280 * 281 * On a local link, the minimum retransmit timeout is 100ms and 282 * variance is set to 0. This will make the sender a little bit more 283 * aggressive on local link. When the connection is not established yet, 284 * there is no need to add an extra 200ms to retransmit timeout because 285 * the initial value is high (1s) and delayed ack is not a problem in 286 * that case. 287 */ 288 #define TCPTV_REXMTSLOP ( TCP_RETRANSHZ/5 ) /* extra 200 ms slop */ 289 290 /* macro to decide when retransmit slop (described above) should be added */ 291 #define TCP_ADD_REXMTSLOP(tp) (tp->t_state >= TCPS_ESTABLISHED) 292 293 #define TCPT_RANGESET(tv, value, tvmin, tvmax, addslop) do { \ 294 (tv) = ((addslop) ? tcp_rexmt_slop : 0) + (value); \ 295 if ((uint32_t)(tv) < (uint32_t)(tvmin)) \ 296 (tv) = (tvmin); \ 297 else if ((uint32_t)(tv) > (uint32_t)(tvmax)) \ 298 (tv) = (tvmax); \ 299 } while(0) 300 301 #define TCP_CONN_KEEPIDLE(tp) \ 302 ((tp)->t_keepidle && \ 303 ((tp)->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) ? \ 304 (tp)->t_keepidle : (uint32_t)tcp_keepidle) 305 #define TCP_CONN_KEEPINIT(tp) \ 306 (((tp)->t_keepinit > 0) ? (tp)->t_keepinit : (uint32_t)tcp_keepinit) 307 #define TCP_CONN_KEEPCNT(tp) \ 308 (((tp)->t_keepcnt > 0) ? (tp)->t_keepcnt : (uint32_t)tcp_keepcnt) 309 #define TCP_CONN_KEEPINTVL(tp) \ 310 (((tp)->t_keepintvl > 0) ? (tp)->t_keepintvl : (uint32_t)tcp_keepintvl) 311 #define TCP_CONN_MAXIDLE(tp) \ 312 (TCP_CONN_KEEPCNT(tp) * TCP_CONN_KEEPINTVL(tp)) 313 314 #define TCP_IDLETIMEOUT(tp) \ 315 (((TCP_ADD_REXMTSLOP(tp)) ? 0 : tcp_rexmt_slop) + tp->t_rxtcur) 316 317 TAILQ_HEAD(tcptailq, tcpcb); 318 319 extern int tcp_keepinit; /* time to establish connection */ 320 extern int tcp_keepidle; /* time before keepalive probes begin */ 321 extern int tcp_keepintvl; /* time between keepalive probes */ 322 extern int tcp_keepcnt; /* number of keepalives */ 323 extern int tcp_delack; /* delayed ack timer */ 324 extern int tcp_maxpersistidle; 325 extern int tcp_msl; 326 extern int tcp_ttl; /* time to live for TCP segs */ 327 extern int tcp_backoff[]; 328 extern int tcp_rexmt_slop; 329 extern u_int32_t tcp_max_persist_timeout; /* Maximum persistence for Zero Window Probes */ 330 331 #define OFFSET_FROM_START(tp, off) ((tcp_now + (off)) - (tp)->tentry.timer_start) 332 333 #endif /* BSD_KERNEL_PRIVATE */ 334 #endif /* !_NETINET_TCP_TIMER_H_ */