root / slirp / tcp_output.c @ b9e82a59
History | View | Annotate | Download (17 kB)
1 |
/*
|
---|---|
2 |
* Copyright (c) 1982, 1986, 1988, 1990, 1993
|
3 |
* The Regents of the University of California. All rights reserved.
|
4 |
*
|
5 |
* Redistribution and use in source and binary forms, with or without
|
6 |
* modification, are permitted provided that the following conditions
|
7 |
* are met:
|
8 |
* 1. Redistributions of source code must retain the above copyright
|
9 |
* notice, this list of conditions and the following disclaimer.
|
10 |
* 2. Redistributions in binary form must reproduce the above copyright
|
11 |
* notice, this list of conditions and the following disclaimer in the
|
12 |
* documentation and/or other materials provided with the distribution.
|
13 |
* 3. Neither the name of the University nor the names of its contributors
|
14 |
* may be used to endorse or promote products derived from this software
|
15 |
* without specific prior written permission.
|
16 |
*
|
17 |
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
18 |
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
19 |
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
20 |
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
21 |
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
22 |
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
23 |
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
24 |
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
25 |
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
26 |
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
27 |
* SUCH DAMAGE.
|
28 |
*
|
29 |
* @(#)tcp_output.c 8.3 (Berkeley) 12/30/93
|
30 |
* tcp_output.c,v 1.3 1994/09/15 10:36:55 davidg Exp
|
31 |
*/
|
32 |
|
33 |
/*
|
34 |
* Changes and additions relating to SLiRP
|
35 |
* Copyright (c) 1995 Danny Gasparovski.
|
36 |
*
|
37 |
* Please read the file COPYRIGHT for the
|
38 |
* terms and conditions of the copyright.
|
39 |
*/
|
40 |
|
41 |
#include <slirp.h> |
42 |
|
43 |
/*
|
44 |
* Since this is only used in "stats socket", we give meaning
|
45 |
* names instead of the REAL names
|
46 |
*/
|
47 |
const char * const tcpstates[] = { |
48 |
/* "CLOSED", "LISTEN", "SYN_SENT", "SYN_RCVD", */
|
49 |
"REDIRECT", "LISTEN", "SYN_SENT", "SYN_RCVD", |
50 |
"ESTABLISHED", "CLOSE_WAIT", "FIN_WAIT_1", "CLOSING", |
51 |
"LAST_ACK", "FIN_WAIT_2", "TIME_WAIT", |
52 |
}; |
53 |
|
54 |
static const u_char tcp_outflags[TCP_NSTATES] = { |
55 |
TH_RST|TH_ACK, 0, TH_SYN, TH_SYN|TH_ACK,
|
56 |
TH_ACK, TH_ACK, TH_FIN|TH_ACK, TH_FIN|TH_ACK, |
57 |
TH_FIN|TH_ACK, TH_ACK, TH_ACK, |
58 |
}; |
59 |
|
60 |
|
61 |
#define MAX_TCPOPTLEN 32 /* max # bytes that go in options */ |
62 |
|
63 |
/*
|
64 |
* Tcp output routine: figure out what should be sent and send it.
|
65 |
*/
|
66 |
int
|
67 |
tcp_output(struct tcpcb *tp)
|
68 |
{ |
69 |
register struct socket *so = tp->t_socket; |
70 |
register long len, win; |
71 |
int off, flags, error;
|
72 |
register struct mbuf *m; |
73 |
register struct tcpiphdr *ti; |
74 |
u_char opt[MAX_TCPOPTLEN]; |
75 |
unsigned optlen, hdrlen;
|
76 |
int idle, sendalot;
|
77 |
|
78 |
DEBUG_CALL("tcp_output");
|
79 |
DEBUG_ARG("tp = %lx", (long )tp); |
80 |
|
81 |
/*
|
82 |
* Determine length of data that should be transmitted,
|
83 |
* and flags that will be used.
|
84 |
* If there is some data or critical controls (SYN, RST)
|
85 |
* to send, then transmit; otherwise, investigate further.
|
86 |
*/
|
87 |
idle = (tp->snd_max == tp->snd_una); |
88 |
if (idle && tp->t_idle >= tp->t_rxtcur)
|
89 |
/*
|
90 |
* We have been idle for "a while" and no acks are
|
91 |
* expected to clock out any data we send --
|
92 |
* slow start to get ack "clock" running again.
|
93 |
*/
|
94 |
tp->snd_cwnd = tp->t_maxseg; |
95 |
again:
|
96 |
sendalot = 0;
|
97 |
off = tp->snd_nxt - tp->snd_una; |
98 |
win = min(tp->snd_wnd, tp->snd_cwnd); |
99 |
|
100 |
flags = tcp_outflags[tp->t_state]; |
101 |
|
102 |
DEBUG_MISC((dfd, " --- tcp_output flags = 0x%x\n",flags));
|
103 |
|
104 |
/*
|
105 |
* If in persist timeout with window of 0, send 1 byte.
|
106 |
* Otherwise, if window is small but nonzero
|
107 |
* and timer expired, we will send what we can
|
108 |
* and go to transmit state.
|
109 |
*/
|
110 |
if (tp->t_force) {
|
111 |
if (win == 0) { |
112 |
/*
|
113 |
* If we still have some data to send, then
|
114 |
* clear the FIN bit. Usually this would
|
115 |
* happen below when it realizes that we
|
116 |
* aren't sending all the data. However,
|
117 |
* if we have exactly 1 byte of unset data,
|
118 |
* then it won't clear the FIN bit below,
|
119 |
* and if we are in persist state, we wind
|
120 |
* up sending the packet without recording
|
121 |
* that we sent the FIN bit.
|
122 |
*
|
123 |
* We can't just blindly clear the FIN bit,
|
124 |
* because if we don't have any more data
|
125 |
* to send then the probe will be the FIN
|
126 |
* itself.
|
127 |
*/
|
128 |
if (off < so->so_snd.sb_cc)
|
129 |
flags &= ~TH_FIN; |
130 |
win = 1;
|
131 |
} else {
|
132 |
tp->t_timer[TCPT_PERSIST] = 0;
|
133 |
tp->t_rxtshift = 0;
|
134 |
} |
135 |
} |
136 |
|
137 |
len = min(so->so_snd.sb_cc, win) - off; |
138 |
|
139 |
if (len < 0) { |
140 |
/*
|
141 |
* If FIN has been sent but not acked,
|
142 |
* but we haven't been called to retransmit,
|
143 |
* len will be -1. Otherwise, window shrank
|
144 |
* after we sent into it. If window shrank to 0,
|
145 |
* cancel pending retransmit and pull snd_nxt
|
146 |
* back to (closed) window. We will enter persist
|
147 |
* state below. If the window didn't close completely,
|
148 |
* just wait for an ACK.
|
149 |
*/
|
150 |
len = 0;
|
151 |
if (win == 0) { |
152 |
tp->t_timer[TCPT_REXMT] = 0;
|
153 |
tp->snd_nxt = tp->snd_una; |
154 |
} |
155 |
} |
156 |
|
157 |
if (len > tp->t_maxseg) {
|
158 |
len = tp->t_maxseg; |
159 |
sendalot = 1;
|
160 |
} |
161 |
if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc))
|
162 |
flags &= ~TH_FIN; |
163 |
|
164 |
win = sbspace(&so->so_rcv); |
165 |
|
166 |
/*
|
167 |
* Sender silly window avoidance. If connection is idle
|
168 |
* and can send all data, a maximum segment,
|
169 |
* at least a maximum default-size segment do it,
|
170 |
* or are forced, do it; otherwise don't bother.
|
171 |
* If peer's buffer is tiny, then send
|
172 |
* when window is at least half open.
|
173 |
* If retransmitting (possibly after persist timer forced us
|
174 |
* to send into a small window), then must resend.
|
175 |
*/
|
176 |
if (len) {
|
177 |
if (len == tp->t_maxseg)
|
178 |
goto send;
|
179 |
if ((1 || idle || tp->t_flags & TF_NODELAY) && |
180 |
len + off >= so->so_snd.sb_cc) |
181 |
goto send;
|
182 |
if (tp->t_force)
|
183 |
goto send;
|
184 |
if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) |
185 |
goto send;
|
186 |
if (SEQ_LT(tp->snd_nxt, tp->snd_max))
|
187 |
goto send;
|
188 |
} |
189 |
|
190 |
/*
|
191 |
* Compare available window to amount of window
|
192 |
* known to peer (as advertised window less
|
193 |
* next expected input). If the difference is at least two
|
194 |
* max size segments, or at least 50% of the maximum possible
|
195 |
* window, then want to send a window update to peer.
|
196 |
*/
|
197 |
if (win > 0) { |
198 |
/*
|
199 |
* "adv" is the amount we can increase the window,
|
200 |
* taking into account that we are limited by
|
201 |
* TCP_MAXWIN << tp->rcv_scale.
|
202 |
*/
|
203 |
long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - |
204 |
(tp->rcv_adv - tp->rcv_nxt); |
205 |
|
206 |
if (adv >= (long) (2 * tp->t_maxseg)) |
207 |
goto send;
|
208 |
if (2 * adv >= (long) so->so_rcv.sb_datalen) |
209 |
goto send;
|
210 |
} |
211 |
|
212 |
/*
|
213 |
* Send if we owe peer an ACK.
|
214 |
*/
|
215 |
if (tp->t_flags & TF_ACKNOW)
|
216 |
goto send;
|
217 |
if (flags & (TH_SYN|TH_RST))
|
218 |
goto send;
|
219 |
if (SEQ_GT(tp->snd_up, tp->snd_una))
|
220 |
goto send;
|
221 |
/*
|
222 |
* If our state indicates that FIN should be sent
|
223 |
* and we have not yet done so, or we're retransmitting the FIN,
|
224 |
* then we need to send.
|
225 |
*/
|
226 |
if (flags & TH_FIN &&
|
227 |
((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una))
|
228 |
goto send;
|
229 |
|
230 |
/*
|
231 |
* TCP window updates are not reliable, rather a polling protocol
|
232 |
* using ``persist'' packets is used to insure receipt of window
|
233 |
* updates. The three ``states'' for the output side are:
|
234 |
* idle not doing retransmits or persists
|
235 |
* persisting to move a small or zero window
|
236 |
* (re)transmitting and thereby not persisting
|
237 |
*
|
238 |
* tp->t_timer[TCPT_PERSIST]
|
239 |
* is set when we are in persist state.
|
240 |
* tp->t_force
|
241 |
* is set when we are called to send a persist packet.
|
242 |
* tp->t_timer[TCPT_REXMT]
|
243 |
* is set when we are retransmitting
|
244 |
* The output side is idle when both timers are zero.
|
245 |
*
|
246 |
* If send window is too small, there is data to transmit, and no
|
247 |
* retransmit or persist is pending, then go to persist state.
|
248 |
* If nothing happens soon, send when timer expires:
|
249 |
* if window is nonzero, transmit what we can,
|
250 |
* otherwise force out a byte.
|
251 |
*/
|
252 |
if (so->so_snd.sb_cc && tp->t_timer[TCPT_REXMT] == 0 && |
253 |
tp->t_timer[TCPT_PERSIST] == 0) {
|
254 |
tp->t_rxtshift = 0;
|
255 |
tcp_setpersist(tp); |
256 |
} |
257 |
|
258 |
/*
|
259 |
* No reason to send a segment, just return.
|
260 |
*/
|
261 |
STAT(tcpstat.tcps_didnuttin++); |
262 |
|
263 |
return (0); |
264 |
|
265 |
send:
|
266 |
/*
|
267 |
* Before ESTABLISHED, force sending of initial options
|
268 |
* unless TCP set not to do any options.
|
269 |
* NOTE: we assume that the IP/TCP header plus TCP options
|
270 |
* always fit in a single mbuf, leaving room for a maximum
|
271 |
* link header, i.e.
|
272 |
* max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MHLEN
|
273 |
*/
|
274 |
optlen = 0;
|
275 |
hdrlen = sizeof (struct tcpiphdr); |
276 |
if (flags & TH_SYN) {
|
277 |
tp->snd_nxt = tp->iss; |
278 |
if ((tp->t_flags & TF_NOOPT) == 0) { |
279 |
u_int16_t mss; |
280 |
|
281 |
opt[0] = TCPOPT_MAXSEG;
|
282 |
opt[1] = 4; |
283 |
mss = htons((u_int16_t) tcp_mss(tp, 0));
|
284 |
memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss)); |
285 |
optlen = 4;
|
286 |
|
287 |
/* if ((tp->t_flags & TF_REQ_SCALE) &&
|
288 |
* ((flags & TH_ACK) == 0 ||
|
289 |
* (tp->t_flags & TF_RCVD_SCALE))) {
|
290 |
* *((u_int32_t *) (opt + optlen)) = htonl(
|
291 |
* TCPOPT_NOP << 24 |
|
292 |
* TCPOPT_WINDOW << 16 |
|
293 |
* TCPOLEN_WINDOW << 8 |
|
294 |
* tp->request_r_scale);
|
295 |
* optlen += 4;
|
296 |
* }
|
297 |
*/
|
298 |
} |
299 |
} |
300 |
|
301 |
/*
|
302 |
* Send a timestamp and echo-reply if this is a SYN and our side
|
303 |
* wants to use timestamps (TF_REQ_TSTMP is set) or both our side
|
304 |
* and our peer have sent timestamps in our SYN's.
|
305 |
*/
|
306 |
/* if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
|
307 |
* (flags & TH_RST) == 0 &&
|
308 |
* ((flags & (TH_SYN|TH_ACK)) == TH_SYN ||
|
309 |
* (tp->t_flags & TF_RCVD_TSTMP))) {
|
310 |
* u_int32_t *lp = (u_int32_t *)(opt + optlen);
|
311 |
*
|
312 |
* / * Form timestamp option as shown in appendix A of RFC 1323. * /
|
313 |
* *lp++ = htonl(TCPOPT_TSTAMP_HDR);
|
314 |
* *lp++ = htonl(tcp_now);
|
315 |
* *lp = htonl(tp->ts_recent);
|
316 |
* optlen += TCPOLEN_TSTAMP_APPA;
|
317 |
* }
|
318 |
*/
|
319 |
hdrlen += optlen; |
320 |
|
321 |
/*
|
322 |
* Adjust data length if insertion of options will
|
323 |
* bump the packet length beyond the t_maxseg length.
|
324 |
*/
|
325 |
if (len > tp->t_maxseg - optlen) {
|
326 |
len = tp->t_maxseg - optlen; |
327 |
sendalot = 1;
|
328 |
} |
329 |
|
330 |
/*
|
331 |
* Grab a header mbuf, attaching a copy of data to
|
332 |
* be transmitted, and initialize the header from
|
333 |
* the template for sends on this connection.
|
334 |
*/
|
335 |
if (len) {
|
336 |
if (tp->t_force && len == 1) |
337 |
STAT(tcpstat.tcps_sndprobe++); |
338 |
else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { |
339 |
STAT(tcpstat.tcps_sndrexmitpack++); |
340 |
STAT(tcpstat.tcps_sndrexmitbyte += len); |
341 |
} else {
|
342 |
STAT(tcpstat.tcps_sndpack++); |
343 |
STAT(tcpstat.tcps_sndbyte += len); |
344 |
} |
345 |
|
346 |
m = m_get(); |
347 |
if (m == NULL) { |
348 |
/* error = ENOBUFS; */
|
349 |
error = 1;
|
350 |
goto out;
|
351 |
} |
352 |
m->m_data += IF_MAXLINKHDR; |
353 |
m->m_len = hdrlen; |
354 |
|
355 |
/*
|
356 |
* This will always succeed, since we make sure our mbufs
|
357 |
* are big enough to hold one MSS packet + header + ... etc.
|
358 |
*/
|
359 |
/* if (len <= MHLEN - hdrlen - max_linkhdr) { */
|
360 |
|
361 |
sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
|
362 |
m->m_len += len; |
363 |
|
364 |
/* } else {
|
365 |
* m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
|
366 |
* if (m->m_next == 0)
|
367 |
* len = 0;
|
368 |
* }
|
369 |
*/
|
370 |
/*
|
371 |
* If we're sending everything we've got, set PUSH.
|
372 |
* (This will keep happy those implementations which only
|
373 |
* give data to the user when a buffer fills or
|
374 |
* a PUSH comes in.)
|
375 |
*/
|
376 |
if (off + len == so->so_snd.sb_cc)
|
377 |
flags |= TH_PUSH; |
378 |
} else {
|
379 |
if (tp->t_flags & TF_ACKNOW)
|
380 |
STAT(tcpstat.tcps_sndacks++); |
381 |
else if (flags & (TH_SYN|TH_FIN|TH_RST)) |
382 |
STAT(tcpstat.tcps_sndctrl++); |
383 |
else if (SEQ_GT(tp->snd_up, tp->snd_una)) |
384 |
STAT(tcpstat.tcps_sndurg++); |
385 |
else
|
386 |
STAT(tcpstat.tcps_sndwinup++); |
387 |
|
388 |
m = m_get(); |
389 |
if (m == NULL) { |
390 |
/* error = ENOBUFS; */
|
391 |
error = 1;
|
392 |
goto out;
|
393 |
} |
394 |
m->m_data += IF_MAXLINKHDR; |
395 |
m->m_len = hdrlen; |
396 |
} |
397 |
|
398 |
ti = mtod(m, struct tcpiphdr *);
|
399 |
|
400 |
memcpy((caddr_t)ti, &tp->t_template, sizeof (struct tcpiphdr)); |
401 |
|
402 |
/*
|
403 |
* Fill in fields, remembering maximum advertised
|
404 |
* window for use in delaying messages about window sizes.
|
405 |
* If resending a FIN, be sure not to use a new sequence number.
|
406 |
*/
|
407 |
if (flags & TH_FIN && tp->t_flags & TF_SENTFIN &&
|
408 |
tp->snd_nxt == tp->snd_max) |
409 |
tp->snd_nxt--; |
410 |
/*
|
411 |
* If we are doing retransmissions, then snd_nxt will
|
412 |
* not reflect the first unsent octet. For ACK only
|
413 |
* packets, we do not want the sequence number of the
|
414 |
* retransmitted packet, we want the sequence number
|
415 |
* of the next unsent octet. So, if there is no data
|
416 |
* (and no SYN or FIN), use snd_max instead of snd_nxt
|
417 |
* when filling in ti_seq. But if we are in persist
|
418 |
* state, snd_max might reflect one byte beyond the
|
419 |
* right edge of the window, so use snd_nxt in that
|
420 |
* case, since we know we aren't doing a retransmission.
|
421 |
* (retransmit and persist are mutually exclusive...)
|
422 |
*/
|
423 |
if (len || (flags & (TH_SYN|TH_FIN)) || tp->t_timer[TCPT_PERSIST])
|
424 |
ti->ti_seq = htonl(tp->snd_nxt); |
425 |
else
|
426 |
ti->ti_seq = htonl(tp->snd_max); |
427 |
ti->ti_ack = htonl(tp->rcv_nxt); |
428 |
if (optlen) {
|
429 |
memcpy((caddr_t)(ti + 1), (caddr_t)opt, optlen);
|
430 |
ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2; |
431 |
} |
432 |
ti->ti_flags = flags; |
433 |
/*
|
434 |
* Calculate receive window. Don't shrink window,
|
435 |
* but avoid silly window syndrome.
|
436 |
*/
|
437 |
if (win < (long)(so->so_rcv.sb_datalen / 4) && win < (long)tp->t_maxseg) |
438 |
win = 0;
|
439 |
if (win > (long)TCP_MAXWIN << tp->rcv_scale) |
440 |
win = (long)TCP_MAXWIN << tp->rcv_scale;
|
441 |
if (win < (long)(tp->rcv_adv - tp->rcv_nxt)) |
442 |
win = (long)(tp->rcv_adv - tp->rcv_nxt);
|
443 |
ti->ti_win = htons((u_int16_t) (win>>tp->rcv_scale)); |
444 |
|
445 |
if (SEQ_GT(tp->snd_up, tp->snd_una)) {
|
446 |
ti->ti_urp = htons((u_int16_t)(tp->snd_up - ntohl(ti->ti_seq))); |
447 |
#ifdef notdef
|
448 |
if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
|
449 |
ti->ti_urp = htons((u_int16_t)(tp->snd_up - tp->snd_nxt)); |
450 |
#endif
|
451 |
ti->ti_flags |= TH_URG; |
452 |
} else
|
453 |
/*
|
454 |
* If no urgent pointer to send, then we pull
|
455 |
* the urgent pointer to the left edge of the send window
|
456 |
* so that it doesn't drift into the send window on sequence
|
457 |
* number wraparound.
|
458 |
*/
|
459 |
tp->snd_up = tp->snd_una; /* drag it along */
|
460 |
|
461 |
/*
|
462 |
* Put TCP length in extended header, and then
|
463 |
* checksum extended header and data.
|
464 |
*/
|
465 |
if (len + optlen)
|
466 |
ti->ti_len = htons((u_int16_t)(sizeof (struct tcphdr) + |
467 |
optlen + len)); |
468 |
ti->ti_sum = cksum(m, (int)(hdrlen + len));
|
469 |
|
470 |
/*
|
471 |
* In transmit state, time the transmission and arrange for
|
472 |
* the retransmit. In persist state, just set snd_max.
|
473 |
*/
|
474 |
if (tp->t_force == 0 || tp->t_timer[TCPT_PERSIST] == 0) { |
475 |
tcp_seq startseq = tp->snd_nxt; |
476 |
|
477 |
/*
|
478 |
* Advance snd_nxt over sequence space of this segment.
|
479 |
*/
|
480 |
if (flags & (TH_SYN|TH_FIN)) {
|
481 |
if (flags & TH_SYN)
|
482 |
tp->snd_nxt++; |
483 |
if (flags & TH_FIN) {
|
484 |
tp->snd_nxt++; |
485 |
tp->t_flags |= TF_SENTFIN; |
486 |
} |
487 |
} |
488 |
tp->snd_nxt += len; |
489 |
if (SEQ_GT(tp->snd_nxt, tp->snd_max)) {
|
490 |
tp->snd_max = tp->snd_nxt; |
491 |
/*
|
492 |
* Time this transmission if not a retransmission and
|
493 |
* not currently timing anything.
|
494 |
*/
|
495 |
if (tp->t_rtt == 0) { |
496 |
tp->t_rtt = 1;
|
497 |
tp->t_rtseq = startseq; |
498 |
STAT(tcpstat.tcps_segstimed++); |
499 |
} |
500 |
} |
501 |
|
502 |
/*
|
503 |
* Set retransmit timer if not currently set,
|
504 |
* and not doing an ack or a keep-alive probe.
|
505 |
* Initial value for retransmit timer is smoothed
|
506 |
* round-trip time + 2 * round-trip time variance.
|
507 |
* Initialize shift counter which is used for backoff
|
508 |
* of retransmit time.
|
509 |
*/
|
510 |
if (tp->t_timer[TCPT_REXMT] == 0 && |
511 |
tp->snd_nxt != tp->snd_una) { |
512 |
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
513 |
if (tp->t_timer[TCPT_PERSIST]) {
|
514 |
tp->t_timer[TCPT_PERSIST] = 0;
|
515 |
tp->t_rxtshift = 0;
|
516 |
} |
517 |
} |
518 |
} else
|
519 |
if (SEQ_GT(tp->snd_nxt + len, tp->snd_max))
|
520 |
tp->snd_max = tp->snd_nxt + len; |
521 |
|
522 |
/*
|
523 |
* Fill in IP length and desired time to live and
|
524 |
* send to IP level. There should be a better way
|
525 |
* to handle ttl and tos; we could keep them in
|
526 |
* the template, but need a way to checksum without them.
|
527 |
*/
|
528 |
m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
|
529 |
|
530 |
{ |
531 |
|
532 |
((struct ip *)ti)->ip_len = m->m_len;
|
533 |
|
534 |
((struct ip *)ti)->ip_ttl = IPDEFTTL;
|
535 |
((struct ip *)ti)->ip_tos = so->so_iptos;
|
536 |
|
537 |
/* #if BSD >= 43 */
|
538 |
/* Don't do IP options... */
|
539 |
/* error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route,
|
540 |
* so->so_options & SO_DONTROUTE, 0);
|
541 |
*/
|
542 |
error = ip_output(so, m); |
543 |
|
544 |
/* #else
|
545 |
* error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route,
|
546 |
* so->so_options & SO_DONTROUTE);
|
547 |
* #endif
|
548 |
*/
|
549 |
} |
550 |
if (error) {
|
551 |
out:
|
552 |
/* if (error == ENOBUFS) {
|
553 |
* tcp_quench(tp->t_inpcb, 0);
|
554 |
* return (0);
|
555 |
* }
|
556 |
*/
|
557 |
/* if ((error == EHOSTUNREACH || error == ENETDOWN)
|
558 |
* && TCPS_HAVERCVDSYN(tp->t_state)) {
|
559 |
* tp->t_softerror = error;
|
560 |
* return (0);
|
561 |
* }
|
562 |
*/
|
563 |
return (error);
|
564 |
} |
565 |
STAT(tcpstat.tcps_sndtotal++); |
566 |
|
567 |
/*
|
568 |
* Data sent (as far as we can tell).
|
569 |
* If this advertises a larger window than any other segment,
|
570 |
* then remember the size of the advertised window.
|
571 |
* Any pending ACK has now been sent.
|
572 |
*/
|
573 |
if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) |
574 |
tp->rcv_adv = tp->rcv_nxt + win; |
575 |
tp->last_ack_sent = tp->rcv_nxt; |
576 |
tp->t_flags &= ~(TF_ACKNOW|TF_DELACK); |
577 |
if (sendalot)
|
578 |
goto again;
|
579 |
|
580 |
return (0); |
581 |
} |
582 |
|
583 |
void
|
584 |
tcp_setpersist(struct tcpcb *tp)
|
585 |
{ |
586 |
int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; |
587 |
|
588 |
/* if (tp->t_timer[TCPT_REXMT])
|
589 |
* panic("tcp_output REXMT");
|
590 |
*/
|
591 |
/*
|
592 |
* Start/restart persistence timer.
|
593 |
*/
|
594 |
TCPT_RANGESET(tp->t_timer[TCPT_PERSIST], |
595 |
t * tcp_backoff[tp->t_rxtshift], |
596 |
TCPTV_PERSMIN, TCPTV_PERSMAX); |
597 |
if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
|
598 |
tp->t_rxtshift++; |
599 |
} |