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33 * @(#)tcp_var.h 8.3 (Berkeley) 4/10/94
34 * tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
41 #include "tcp_timer.h"
44 * Tcp control block, one per tcp; fields:
47 struct tcpiphdr *seg_next; /* sequencing queue */
48 struct tcpiphdr *seg_prev;
49 short t_state; /* state of this connection */
50 short t_timer[TCPT_NTIMERS]; /* tcp timers */
51 short t_rxtshift; /* log(2) of rexmt exp. backoff */
52 short t_rxtcur; /* current retransmit value */
53 short t_dupacks; /* consecutive dup acks recd */
54 u_short t_maxseg; /* maximum segment size */
55 char t_force; /* 1 if forcing out a byte */
57 #define TF_ACKNOW 0x0001 /* ack peer immediately */
58 #define TF_DELACK 0x0002 /* ack, but try to delay it */
59 #define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
60 #define TF_NOOPT 0x0008 /* don't use tcp options */
61 #define TF_SENTFIN 0x0010 /* have sent FIN */
62 #define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
63 #define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
64 #define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
65 #define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
66 #define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
68 /* Make it static for now */
69 /* struct tcpiphdr *t_template; / * skeletal packet for transmit */
70 struct tcpiphdr t_template;
72 struct socket *t_socket; /* back pointer to socket */
74 * The following fields are used as in the protocol specification.
75 * See RFC783, Dec. 1981, page 21.
77 /* send sequence variables */
78 tcp_seq snd_una; /* send unacknowledged */
79 tcp_seq snd_nxt; /* send next */
80 tcp_seq snd_up; /* send urgent pointer */
81 tcp_seq snd_wl1; /* window update seg seq number */
82 tcp_seq snd_wl2; /* window update seg ack number */
83 tcp_seq iss; /* initial send sequence number */
84 u_int32_t snd_wnd; /* send window */
85 /* receive sequence variables */
86 u_int32_t rcv_wnd; /* receive window */
87 tcp_seq rcv_nxt; /* receive next */
88 tcp_seq rcv_up; /* receive urgent pointer */
89 tcp_seq irs; /* initial receive sequence number */
91 * Additional variables for this implementation.
93 /* receive variables */
94 tcp_seq rcv_adv; /* advertised window */
95 /* retransmit variables */
96 tcp_seq snd_max; /* highest sequence number sent;
97 * used to recognize retransmits
99 /* congestion control (for slow start, source quench, retransmit after loss) */
100 u_int32_t snd_cwnd; /* congestion-controlled window */
101 u_int32_t snd_ssthresh; /* snd_cwnd size threshold for
102 * for slow start exponential to
106 * transmit timing stuff. See below for scale of srtt and rttvar.
107 * "Variance" is actually smoothed difference.
109 short t_idle; /* inactivity time */
110 short t_rtt; /* round trip time */
111 tcp_seq t_rtseq; /* sequence number being timed */
112 short t_srtt; /* smoothed round-trip time */
113 short t_rttvar; /* variance in round-trip time */
114 u_short t_rttmin; /* minimum rtt allowed */
115 u_int32_t max_sndwnd; /* largest window peer has offered */
117 /* out-of-band data */
118 char t_oobflags; /* have some */
119 char t_iobc; /* input character */
120 #define TCPOOB_HAVEDATA 0x01
121 #define TCPOOB_HADDATA 0x02
122 short t_softerror; /* possible error not yet reported */
124 /* RFC 1323 variables */
125 u_char snd_scale; /* window scaling for send window */
126 u_char rcv_scale; /* window scaling for recv window */
127 u_char request_r_scale; /* pending window scaling */
128 u_char requested_s_scale;
129 u_int32_t ts_recent; /* timestamp echo data */
130 u_int32_t ts_recent_age; /* when last updated */
131 tcp_seq last_ack_sent;
135 #define sototcpcb(so) ((so)->so_tcpcb)
138 * The smoothed round-trip time and estimated variance
139 * are stored as fixed point numbers scaled by the values below.
140 * For convenience, these scales are also used in smoothing the average
141 * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
142 * With these scales, srtt has 3 bits to the right of the binary point,
143 * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
144 * binary point, and is smoothed with an ALPHA of 0.75.
146 #define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
147 #define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
148 #define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
149 #define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */
152 * The initial retransmission should happen at rtt + 4 * rttvar.
153 * Because of the way we do the smoothing, srtt and rttvar
154 * will each average +1/2 tick of bias. When we compute
155 * the retransmit timer, we want 1/2 tick of rounding and
156 * 1 extra tick because of +-1/2 tick uncertainty in the
157 * firing of the timer. The bias will give us exactly the
158 * 1.5 tick we need. But, because the bias is
159 * statistical, we have to test that we don't drop below
160 * the minimum feasible timer (which is 2 ticks).
161 * This macro assumes that the value of TCP_RTTVAR_SCALE
162 * is the same as the multiplier for rttvar.
164 #define TCP_REXMTVAL(tp) \
165 (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
170 * Many of these should be kept per connection,
171 * but that's inconvenient at the moment.
174 u_long tcps_connattempt; /* connections initiated */
175 u_long tcps_accepts; /* connections accepted */
176 u_long tcps_connects; /* connections established */
177 u_long tcps_drops; /* connections dropped */
178 u_long tcps_conndrops; /* embryonic connections dropped */
179 u_long tcps_closed; /* conn. closed (includes drops) */
180 u_long tcps_segstimed; /* segs where we tried to get rtt */
181 u_long tcps_rttupdated; /* times we succeeded */
182 u_long tcps_delack; /* delayed acks sent */
183 u_long tcps_timeoutdrop; /* conn. dropped in rxmt timeout */
184 u_long tcps_rexmttimeo; /* retransmit timeouts */
185 u_long tcps_persisttimeo; /* persist timeouts */
186 u_long tcps_keeptimeo; /* keepalive timeouts */
187 u_long tcps_keepprobe; /* keepalive probes sent */
188 u_long tcps_keepdrops; /* connections dropped in keepalive */
190 u_long tcps_sndtotal; /* total packets sent */
191 u_long tcps_sndpack; /* data packets sent */
192 u_long tcps_sndbyte; /* data bytes sent */
193 u_long tcps_sndrexmitpack; /* data packets retransmitted */
194 u_long tcps_sndrexmitbyte; /* data bytes retransmitted */
195 u_long tcps_sndacks; /* ack-only packets sent */
196 u_long tcps_sndprobe; /* window probes sent */
197 u_long tcps_sndurg; /* packets sent with URG only */
198 u_long tcps_sndwinup; /* window update-only packets sent */
199 u_long tcps_sndctrl; /* control (SYN|FIN|RST) packets sent */
201 u_long tcps_rcvtotal; /* total packets received */
202 u_long tcps_rcvpack; /* packets received in sequence */
203 u_long tcps_rcvbyte; /* bytes received in sequence */
204 u_long tcps_rcvbadsum; /* packets received with ccksum errs */
205 u_long tcps_rcvbadoff; /* packets received with bad offset */
206 /* u_long tcps_rcvshort; */ /* packets received too short */
207 u_long tcps_rcvduppack; /* duplicate-only packets received */
208 u_long tcps_rcvdupbyte; /* duplicate-only bytes received */
209 u_long tcps_rcvpartduppack; /* packets with some duplicate data */
210 u_long tcps_rcvpartdupbyte; /* dup. bytes in part-dup. packets */
211 u_long tcps_rcvoopack; /* out-of-order packets received */
212 u_long tcps_rcvoobyte; /* out-of-order bytes received */
213 u_long tcps_rcvpackafterwin; /* packets with data after window */
214 u_long tcps_rcvbyteafterwin; /* bytes rcvd after window */
215 u_long tcps_rcvafterclose; /* packets rcvd after "close" */
216 u_long tcps_rcvwinprobe; /* rcvd window probe packets */
217 u_long tcps_rcvdupack; /* rcvd duplicate acks */
218 u_long tcps_rcvacktoomuch; /* rcvd acks for unsent data */
219 u_long tcps_rcvackpack; /* rcvd ack packets */
220 u_long tcps_rcvackbyte; /* bytes acked by rcvd acks */
221 u_long tcps_rcvwinupd; /* rcvd window update packets */
222 /* u_long tcps_pawsdrop; */ /* segments dropped due to PAWS */
223 u_long tcps_predack; /* times hdr predict ok for acks */
224 u_long tcps_preddat; /* times hdr predict ok for data pkts */
225 u_long tcps_socachemiss; /* tcp_last_so misses */
226 u_long tcps_didnuttin; /* Times tcp_output didn't do anything XXX */
229 extern struct tcpstat tcpstat; /* tcp statistics */
232 extern u_int32_t tcp_now; /* for RFC 1323 timestamps */
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