1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)tcp_var.h 7.10 (Berkeley) 06/28/90 8 */ 9 10 /* 11 * Kernel variables for tcp. 12 */ 13 14 /* 15 * Tcp control block, one per tcp; fields: 16 */ 17 struct tcpcb { 18 struct tcpiphdr *seg_next; /* sequencing queue */ 19 struct tcpiphdr *seg_prev; 20 short t_state; /* state of this connection */ 21 short t_timer[TCPT_NTIMERS]; /* tcp timers */ 22 short t_rxtshift; /* log(2) of rexmt exp. backoff */ 23 short t_rxtcur; /* current retransmit value */ 24 short t_dupacks; /* consecutive dup acks recd */ 25 u_short t_maxseg; /* maximum segment size */ 26 char t_force; /* 1 if forcing out a byte */ 27 u_char t_flags; 28 #define TF_ACKNOW 0x01 /* ack peer immediately */ 29 #define TF_DELACK 0x02 /* ack, but try to delay it */ 30 #define TF_NODELAY 0x04 /* don't delay packets to coalesce */ 31 #define TF_NOOPT 0x08 /* don't use tcp options */ 32 #define TF_SENTFIN 0x10 /* have sent FIN */ 33 struct tcpiphdr *t_template; /* skeletal packet for transmit */ 34 struct inpcb *t_inpcb; /* back pointer to internet pcb */ 35 /* 36 * The following fields are used as in the protocol specification. 37 * See RFC783, Dec. 1981, page 21. 38 */ 39 /* send sequence variables */ 40 tcp_seq snd_una; /* send unacknowledged */ 41 tcp_seq snd_nxt; /* send next */ 42 tcp_seq snd_up; /* send urgent pointer */ 43 tcp_seq snd_wl1; /* window update seg seq number */ 44 tcp_seq snd_wl2; /* window update seg ack number */ 45 tcp_seq iss; /* initial send sequence number */ 46 u_short snd_wnd; /* send window */ 47 /* receive sequence variables */ 48 u_short rcv_wnd; /* receive window */ 49 tcp_seq rcv_nxt; /* receive next */ 50 tcp_seq rcv_up; /* receive urgent pointer */ 51 tcp_seq irs; /* initial receive sequence number */ 52 /* 53 * Additional variables for this implementation. 54 */ 55 /* receive variables */ 56 tcp_seq rcv_adv; /* advertised window */ 57 /* retransmit variables */ 58 tcp_seq snd_max; /* highest sequence number sent; 59 * used to recognize retransmits 60 */ 61 /* congestion control (for slow start, source quench, retransmit after loss) */ 62 u_short snd_cwnd; /* congestion-controlled window */ 63 u_short snd_ssthresh; /* snd_cwnd size threshhold for 64 * for slow start exponential to 65 * linear switch 66 */ 67 /* 68 * transmit timing stuff. See below for scale of srtt and rttvar. 69 * "Variance" is actually smoothed difference. 70 */ 71 short t_idle; /* inactivity time */ 72 short t_rtt; /* round trip time */ 73 tcp_seq t_rtseq; /* sequence number being timed */ 74 short t_srtt; /* smoothed round-trip time */ 75 short t_rttvar; /* variance in round-trip time */ 76 u_short t_rttmin; /* minimum rtt allowed */ 77 u_short max_sndwnd; /* largest window peer has offered */ 78 79 /* out-of-band data */ 80 char t_oobflags; /* have some */ 81 char t_iobc; /* input character */ 82 #define TCPOOB_HAVEDATA 0x01 83 #define TCPOOB_HADDATA 0x02 84 short t_softerror; /* possible error not yet reported */ 85 }; 86 87 #define intotcpcb(ip) ((struct tcpcb *)(ip)->inp_ppcb) 88 #define sototcpcb(so) (intotcpcb(sotoinpcb(so))) 89 90 /* 91 * The smoothed round-trip time and estimated variance 92 * are stored as fixed point numbers scaled by the values below. 93 * For convenience, these scales are also used in smoothing the average 94 * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed). 95 * With these scales, srtt has 3 bits to the right of the binary point, 96 * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the 97 * binary point, and is smoothed with an ALPHA of 0.75. 98 */ 99 #define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */ 100 #define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */ 101 #define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */ 102 #define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */ 103 104 /* 105 * The initial retransmission should happen at rtt + 4 * rttvar. 106 * Because of the way we do the smoothing, srtt and rttvar 107 * will each average +1/2 tick of bias. When we compute 108 * the retransmit timer, we want 1/2 tick of rounding and 109 * 1 extra tick because of +-1/2 tick uncertainty in the 110 * firing of the timer. The bias will give us exactly the 111 * 1.5 tick we need. But, because the bias is 112 * statistical, we have to test that we don't drop below 113 * the minimum feasible timer (which is 2 ticks). 114 * This macro assumes that the value of TCP_RTTVAR_SCALE 115 * is the same as the multiplier for rttvar. 116 */ 117 #define TCP_REXMTVAL(tp) \ 118 (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar) 119 120 /* XXX 121 * We want to avoid doing m_pullup on incoming packets but that 122 * means avoiding dtom on the tcp reassembly code. That in turn means 123 * keeping an mbuf pointer in the reassembly queue (since we might 124 * have a cluster). As a quick hack, the source & destination 125 * port numbers (which are no longer needed once we've located the 126 * tcpcb) are overlayed with an mbuf pointer. 127 */ 128 #define REASS_MBUF(ti) (*(struct mbuf **)&((ti)->ti_t)) 129 130 /* 131 * TCP statistics. 132 * Many of these should be kept per connection, 133 * but that's inconvenient at the moment. 134 */ 135 struct tcpstat { 136 u_long tcps_connattempt; /* connections initiated */ 137 u_long tcps_accepts; /* connections accepted */ 138 u_long tcps_connects; /* connections established */ 139 u_long tcps_drops; /* connections dropped */ 140 u_long tcps_conndrops; /* embryonic connections dropped */ 141 u_long tcps_closed; /* conn. closed (includes drops) */ 142 u_long tcps_segstimed; /* segs where we tried to get rtt */ 143 u_long tcps_rttupdated; /* times we succeeded */ 144 u_long tcps_delack; /* delayed acks sent */ 145 u_long tcps_timeoutdrop; /* conn. dropped in rxmt timeout */ 146 u_long tcps_rexmttimeo; /* retransmit timeouts */ 147 u_long tcps_persisttimeo; /* persist timeouts */ 148 u_long tcps_keeptimeo; /* keepalive timeouts */ 149 u_long tcps_keepprobe; /* keepalive probes sent */ 150 u_long tcps_keepdrops; /* connections dropped in keepalive */ 151 152 u_long tcps_sndtotal; /* total packets sent */ 153 u_long tcps_sndpack; /* data packets sent */ 154 u_long tcps_sndbyte; /* data bytes sent */ 155 u_long tcps_sndrexmitpack; /* data packets retransmitted */ 156 u_long tcps_sndrexmitbyte; /* data bytes retransmitted */ 157 u_long tcps_sndacks; /* ack-only packets sent */ 158 u_long tcps_sndprobe; /* window probes sent */ 159 u_long tcps_sndurg; /* packets sent with URG only */ 160 u_long tcps_sndwinup; /* window update-only packets sent */ 161 u_long tcps_sndctrl; /* control (SYN|FIN|RST) packets sent */ 162 163 u_long tcps_rcvtotal; /* total packets received */ 164 u_long tcps_rcvpack; /* packets received in sequence */ 165 u_long tcps_rcvbyte; /* bytes received in sequence */ 166 u_long tcps_rcvbadsum; /* packets received with ccksum errs */ 167 u_long tcps_rcvbadoff; /* packets received with bad offset */ 168 u_long tcps_rcvshort; /* packets received too short */ 169 u_long tcps_rcvduppack; /* duplicate-only packets received */ 170 u_long tcps_rcvdupbyte; /* duplicate-only bytes received */ 171 u_long tcps_rcvpartduppack; /* packets with some duplicate data */ 172 u_long tcps_rcvpartdupbyte; /* dup. bytes in part-dup. packets */ 173 u_long tcps_rcvoopack; /* out-of-order packets received */ 174 u_long tcps_rcvoobyte; /* out-of-order bytes received */ 175 u_long tcps_rcvpackafterwin; /* packets with data after window */ 176 u_long tcps_rcvbyteafterwin; /* bytes rcvd after window */ 177 u_long tcps_rcvafterclose; /* packets rcvd after "close" */ 178 u_long tcps_rcvwinprobe; /* rcvd window probe packets */ 179 u_long tcps_rcvdupack; /* rcvd duplicate acks */ 180 u_long tcps_rcvacktoomuch; /* rcvd acks for unsent data */ 181 u_long tcps_rcvackpack; /* rcvd ack packets */ 182 u_long tcps_rcvackbyte; /* bytes acked by rcvd acks */ 183 u_long tcps_rcvwinupd; /* rcvd window update packets */ 184 }; 185 186 #ifdef KERNEL 187 struct inpcb tcb; /* head of queue of active tcpcb's */ 188 struct tcpstat tcpstat; /* tcp statistics */ 189 struct tcpiphdr *tcp_template(); 190 struct tcpcb *tcp_close(), *tcp_drop(); 191 struct tcpcb *tcp_timers(), *tcp_disconnect(), *tcp_usrclosed(); 192 #endif 193