tcp_output.c@ 30016

Last change on this file since 30016 was 30016, checked in by vboxsync, 15 years ago
NAT: clean up.
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1	/* $Id: tcp_output.c 30016 2010-06-03 18:31:14Z vboxsync $ */
2	/** @file
3	* NAT - TCP output.
4	*/
5
6	/*
7	* Copyright (C) 2006-2010 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*/
17
18	/*
19	* This code is based on:
20	*
21	* Copyright (c) 1982, 1986, 1988, 1990, 1993
22	* The Regents of the University of California. All rights reserved.
23	*
24	* Redistribution and use in source and binary forms, with or without
25	* modification, are permitted provided that the following conditions
26	* are met:
27	* 1. Redistributions of source code must retain the above copyright
28	* notice, this list of conditions and the following disclaimer.
29	* 2. Redistributions in binary form must reproduce the above copyright
30	* notice, this list of conditions and the following disclaimer in the
31	* documentation and/or other materials provided with the distribution.
32	* 3. All advertising materials mentioning features or use of this software
33	* must display the following acknowledgement:
34	* This product includes software developed by the University of
35	* California, Berkeley and its contributors.
36	* 4. Neither the name of the University nor the names of its contributors
37	* may be used to endorse or promote products derived from this software
38	* without specific prior written permission.
39	*
40	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
41	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
44	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50	* SUCH DAMAGE.
51	*
52	* @(#)tcp_output.c 8.3 (Berkeley) 12/30/93
53	* tcp_output.c,v 1.3 1994/09/15 10:36:55 davidg Exp
54	*/
55
56	/*
57	* Changes and additions relating to SLiRP
58	* Copyright (c) 1995 Danny Gasparovski.
59	*
60	* Please read the file COPYRIGHT for the
61	* terms and conditions of the copyright.
62	*/
63
64	#include <slirp.h>
65
66	/*
67	* Since this is only used in "stats socket", we give meaning
68	* names instead of the REAL names
69	*/
70	const char * const tcpstates[] =
71	{
72	/* "CLOSED", "LISTEN", "SYN_SENT", "SYN_RCVD", */
73	"REDIRECT", "LISTEN", "SYN_SENT", "SYN_RCVD",
74	"ESTABLISHED", "CLOSE_WAIT", "FIN_WAIT_1", "CLOSING",
75	"LAST_ACK", "FIN_WAIT_2", "TIME_WAIT",
76	};
77
78	static const u_char tcp_outflags[TCP_NSTATES] =
79	{
80	TH_RST\|TH_ACK, 0, TH_SYN, TH_SYN\|TH_ACK,
81	TH_ACK, TH_ACK, TH_FIN\|TH_ACK, TH_FIN\|TH_ACK,
82	TH_FIN\|TH_ACK, TH_ACK, TH_ACK,
83	};
84
85
86	#define MAX_TCPOPTLEN 32 /* max # bytes that go in options */
87
88	/*
89	* Tcp output routine: figure out what should be sent and send it.
90	*/
91	int
92	tcp_output(PNATState pData, register struct tcpcb *tp)
93	{
94	register struct socket *so = tp->t_socket;
95	register long len, win;
96	int off, flags, error;
97	register struct mbuf *m = NULL;
98	register struct tcpiphdr *ti;
99	u_char opt[MAX_TCPOPTLEN];
100	unsigned optlen, hdrlen;
101	int idle, sendalot;
102	int size;
103
104	DEBUG_CALL("tcp_output");
105	DEBUG_ARG("tp = %lx", (long )tp);
106
107	/*
108	* Determine length of data that should be transmitted,
109	* and flags that will be used.
110	* If there is some data or critical controls (SYN, RST)
111	* to send, then transmit; otherwise, investigate further.
112	*/
113	idle = (tp->snd_max == tp->snd_una);
114	if (idle && tp->t_idle >= tp->t_rxtcur)
115	/*
116	* We have been idle for "a while" and no acks are
117	* expected to clock out any data we send --
118	* slow start to get ack "clock" running again.
119	*/
120	tp->snd_cwnd = tp->t_maxseg;
121
122	again:
123	sendalot = 0;
124	off = tp->snd_nxt - tp->snd_una;
125	win = min(tp->snd_wnd, tp->snd_cwnd);
126
127	flags = tcp_outflags[tp->t_state];
128
129	DEBUG_MISC((dfd, " --- tcp_output flags = 0x%x\n",flags));
130
131	/*
132	* If in persist timeout with window of 0, send 1 byte.
133	* Otherwise, if window is small but nonzero
134	* and timer expired, we will send what we can
135	* and go to transmit state.
136	*/
137	if (tp->t_force)
138	{
139	if (win == 0)
140	{
141	/*
142	* If we still have some data to send, then
143	* clear the FIN bit. Usually this would
144	* happen below when it realizes that we
145	* aren't sending all the data. However,
146	* if we have exactly 1 byte of unset data,
147	* then it won't clear the FIN bit below,
148	* and if we are in persist state, we wind
149	* up sending the packet without recording
150	* that we sent the FIN bit.
151	*
152	* We can't just blindly clear the FIN bit,
153	* because if we don't have any more data
154	* to send then the probe will be the FIN
155	* itself.
156	*/
157	if (off < so->so_snd.sb_cc)
158	flags &= ~TH_FIN;
159	win = 1;
160	}
161	else
162	{
163	tp->t_timer[TCPT_PERSIST] = 0;
164	tp->t_rxtshift = 0;
165	}
166	}
167
168	len = min(so->so_snd.sb_cc, win) - off;
169	if (len < 0)
170	{
171	/*
172	* If FIN has been sent but not acked,
173	* but we haven't been called to retransmit,
174	* len will be -1. Otherwise, window shrank
175	* after we sent into it. If window shrank to 0,
176	* cancel pending retransmit and pull snd_nxt
177	* back to (closed) window. We will enter persist
178	* state below. If the window didn't close completely,
179	* just wait for an ACK.
180	*/
181	len = 0;
182	if (win == 0)
183	{
184	tp->t_timer[TCPT_REXMT] = 0;
185	tp->snd_nxt = tp->snd_una;
186	}
187	}
188	if (len > tp->t_maxseg)
189	{
190	len = tp->t_maxseg;
191	sendalot = 1;
192	}
193	if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc))
194	flags &= ~TH_FIN;
195
196	win = sbspace(&so->so_rcv);
197
198	/*
199	* Sender silly window avoidance. If connection is idle
200	* and can send all data, a maximum segment,
201	* at least a maximum default-size segment do it,
202	* or are forced, do it; otherwise don't bother.
203	* If peer's buffer is tiny, then send
204	* when window is at least half open.
205	* If retransmitting (possibly after persist timer forced us
206	* to send into a small window), then must resend.
207	*/
208	if (len)
209	{
210	if (len == tp->t_maxseg)
211	goto send;
212	if ((1 \|\| idle \|\| tp->t_flags & TF_NODELAY) &&
213	len + off >= so->so_snd.sb_cc)
214	goto send;
215	if (tp->t_force)
216	goto send;
217	if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
218	goto send;
219	if (SEQ_LT(tp->snd_nxt, tp->snd_max))
220	goto send;
221	}
222
223	/*
224	* Compare available window to amount of window
225	* known to peer (as advertised window less
226	* next expected input). If the difference is at least two
227	* max size segments, or at least 50% of the maximum possible
228	* window, then want to send a window update to peer.
229	*/
230	if (win > 0)
231	{
232	/*
233	* "adv" is the amount we can increase the window,
234	* taking into account that we are limited by
235	* TCP_MAXWIN << tp->rcv_scale.
236	*/
237	long adv = min(win,
238	(long)TCP_MAXWIN << tp->rcv_scale) -
239	(tp->rcv_adv - tp->rcv_nxt);
240
241	if (adv >= (long) (2 * tp->t_maxseg))
242	goto send;
243	if (2 * adv >= (long) so->so_rcv.sb_datalen)
244	goto send;
245	}
246
247	/*
248	* Send if we owe peer an ACK.
249	*/
250	if (tp->t_flags & TF_ACKNOW)
251	goto send;
252	if (flags & (TH_SYN\|TH_RST))
253	goto send;
254	if (SEQ_GT(tp->snd_up, tp->snd_una))
255	goto send;
256	/*
257	* If our state indicates that FIN should be sent
258	* and we have not yet done so, or we're retransmitting the FIN,
259	* then we need to send.
260	*/
261	if ( flags & TH_FIN
262	&& ((tp->t_flags & TF_SENTFIN) == 0 \|\| tp->snd_nxt == tp->snd_una))
263	goto send;
264
265	/*
266	* TCP window updates are not reliable, rather a polling protocol
267	* using ``persist'' packets is used to insure receipt of window
268	* updates. The three ``states'' for the output side are:
269	* idle not doing retransmits or persists
270	* persisting to move a small or zero window
271	* (re)transmitting and thereby not persisting
272	*
273	* tp->t_timer[TCPT_PERSIST]
274	* is set when we are in persist state.
275	* tp->t_force
276	* is set when we are called to send a persist packet.
277	* tp->t_timer[TCPT_REXMT]
278	* is set when we are retransmitting
279	* The output side is idle when both timers are zero.
280	*
281	* If send window is too small, there is data to transmit, and no
282	* retransmit or persist is pending, then go to persist state.
283	* If nothing happens soon, send when timer expires:
284	* if window is nonzero, transmit what we can,
285	* otherwise force out a byte.
286	*/
287	if ( so->so_snd.sb_cc
288	&& tp->t_timer[TCPT_REXMT] == 0
289	&& tp->t_timer[TCPT_PERSIST] == 0)
290	{
291	tp->t_rxtshift = 0;
292	tcp_setpersist(tp);
293	}
294
295	/*
296	* No reason to send a segment, just return.
297	*/
298	tcpstat.tcps_didnuttin++;
299
300	return (0);
301
302	send:
303	/*
304	* Before ESTABLISHED, force sending of initial options
305	* unless TCP set not to do any options.
306	* NOTE: we assume that the IP/TCP header plus TCP options
307	* always fit in a single mbuf, leaving room for a maximum
308	* link header, i.e.
309	* max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MHLEN
310	*/
311	optlen = 0;
312	hdrlen = sizeof (struct tcpiphdr);
313	if (flags & TH_SYN)
314	{
315	tp->snd_nxt = tp->iss;
316	if ((tp->t_flags & TF_NOOPT) == 0)
317	{
318	u_int16_t mss;
319
320	opt[0] = TCPOPT_MAXSEG;
321	opt[1] = 4;
322	mss = RT_H2N_U16((u_int16_t) tcp_mss(pData, tp, 0));
323	memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss));
324	optlen = 4;
325
326	#if 0
327	if ( (tp->t_flags & TF_REQ_SCALE)
328	&& ( (flags & TH_ACK) == 0
329	\|\| (tp->t_flags & TF_RCVD_SCALE)))
330	{
331	((u_int32_t ) (opt + optlen)) = RT_H2N_U32( TCPOPT_NOP << 24
332	\| TCPOPT_WINDOW << 16
333	\| TCPOLEN_WINDOW << 8
334	\| tp->request_r_scale);
335	optlen += 4;
336	}
337	#endif
338	}
339	}
340
341	/*
342	* Send a timestamp and echo-reply if this is a SYN and our side
343	* wants to use timestamps (TF_REQ_TSTMP is set) or both our side
344	* and our peer have sent timestamps in our SYN's.
345	*/
346	#if 0
347	if ( (tp->t_flags & (TF_REQ_TSTMP\|TF_NOOPT)) == TF_REQ_TSTMP
348	&& (flags & TH_RST) == 0
349	&& ( (flags & (TH_SYN\|TH_ACK)) == TH_SYN
350	\|\| (tp->t_flags & TF_RCVD_TSTMP)))
351	{
352	u_int32_t lp = (u_int32_t )(opt + optlen);
353
354	/* Form timestamp option as shown in appendix A of RFC 1323. */
355	*lp++ = RT_H2N_U32_C(TCPOPT_TSTAMP_HDR);
356	*lp++ = RT_H2N_U32(tcp_now);
357	*lp = RT_H2N_U32(tp->ts_recent);
358	optlen += TCPOLEN_TSTAMP_APPA;
359	}
360	#endif
361	hdrlen += optlen;
362
363	/*
364	* Adjust data length if insertion of options will
365	* bump the packet length beyond the t_maxseg length.
366	*/
367	if (len > tp->t_maxseg - optlen)
368	{
369	len = tp->t_maxseg - optlen;
370	sendalot = 1;
371	}
372
373	/*
374	* Grab a header mbuf, attaching a copy of data to
375	* be transmitted, and initialize the header from
376	* the template for sends on this connection.
377	*/
378	if (len)
379	{
380	if (tp->t_force && len == 1)
381	tcpstat.tcps_sndprobe++;
382	else if (SEQ_LT(tp->snd_nxt, tp->snd_max))
383	{
384	tcpstat.tcps_sndrexmitpack++;
385	tcpstat.tcps_sndrexmitbyte += len;
386	}
387	else
388	{
389	tcpstat.tcps_sndpack++;
390	tcpstat.tcps_sndbyte += len;
391	}
392
393	size = MCLBYTES;
394	if ((len + hdrlen + ETH_HLEN) < MSIZE)
395	size = MCLBYTES;
396	else if ((len + hdrlen + ETH_HLEN) < MCLBYTES)
397	size = MCLBYTES;
398	else if((len + hdrlen + ETH_HLEN) < MJUM9BYTES)
399	size = MJUM9BYTES;
400	else if ((len + hdrlen + ETH_HLEN) < MJUM16BYTES)
401	size = MJUM16BYTES;
402	else
403	AssertMsgFailed(("Unsupported size"));
404	m = m_getjcl(pData, M_NOWAIT, MT_HEADER, M_PKTHDR, size);
405	if (m == NULL)
406	{
407	/* error = ENOBUFS; */
408	error = 1;
409	goto out;
410	}
411	m->m_data += if_maxlinkhdr;
412	m->m_pkthdr.header = mtod(m, void *);
413	m->m_len = hdrlen;
414
415	/*
416	* This will always succeed, since we make sure our mbufs
417	* are big enough to hold one MSS packet + header + ... etc.
418	*/
419	#if 0
420	if (len <= MHLEN - hdrlen - max_linkhdr)
421	{
422	#endif
423	sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
424	m->m_len += len;
425	#if 0
426	}
427	else
428	{
429	m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
430	if (m->m_next == 0)
431	len = 0;
432	}
433	#endif
434	/*
435	* If we're sending everything we've got, set PUSH.
436	* (This will keep happy those implementations which only
437	* give data to the user when a buffer fills or
438	* a PUSH comes in.)
439	*/
440	if (off + len == so->so_snd.sb_cc)
441	flags \|= TH_PUSH;
442	}
443	else
444	{
445	if (tp->t_flags & TF_ACKNOW)
446	tcpstat.tcps_sndacks++;
447	else if (flags & (TH_SYN\|TH_FIN\|TH_RST))
448	tcpstat.tcps_sndctrl++;
449	else if (SEQ_GT(tp->snd_up, tp->snd_una))
450	tcpstat.tcps_sndurg++;
451	else
452	tcpstat.tcps_sndwinup++;
453
454	if ((hdrlen + ETH_HLEN) < MSIZE)
455	{
456	size = MCLBYTES;
457	}
458	else if ((hdrlen + ETH_HLEN) < MCLBYTES)
459	{
460	size = MCLBYTES;
461	}
462	else if((hdrlen + ETH_HLEN) < MJUM9BYTES)
463	{
464	size = MJUM9BYTES;
465	}
466	else if ((hdrlen + ETH_HLEN) < MJUM16BYTES)
467	{
468	size = MJUM16BYTES;
469	}
470	else
471	{
472	AssertMsgFailed(("Unsupported size"));
473	}
474	m = m_getjcl(pData, M_NOWAIT, MT_HEADER, M_PKTHDR, size);
475	if (m == NULL)
476	{
477	/* error = ENOBUFS; */
478	error = 1;
479	goto out;
480	}
481	m->m_data += if_maxlinkhdr;
482	m->m_pkthdr.header = mtod(m, void *);
483	m->m_len = hdrlen;
484	}
485
486	ti = mtod(m, struct tcpiphdr *);
487
488	memcpy((caddr_t)ti, &tp->t_template, sizeof (struct tcpiphdr));
489
490	/*
491	* Fill in fields, remembering maximum advertised
492	* window for use in delaying messages about window sizes.
493	* If resending a FIN, be sure not to use a new sequence number.
494	*/
495	if ( flags & TH_FIN
496	&& tp->t_flags & TF_SENTFIN
497	&& tp->snd_nxt == tp->snd_max)
498	tp->snd_nxt--;
499	/*
500	* If we are doing retransmissions, then snd_nxt will
501	* not reflect the first unsent octet. For ACK only
502	* packets, we do not want the sequence number of the
503	* retransmitted packet, we want the sequence number
504	* of the next unsent octet. So, if there is no data
505	* (and no SYN or FIN), use snd_max instead of snd_nxt
506	* when filling in ti_seq. But if we are in persist
507	* state, snd_max might reflect one byte beyond the
508	* right edge of the window, so use snd_nxt in that
509	* case, since we know we aren't doing a retransmission.
510	* (retransmit and persist are mutually exclusive...)
511	*/
512	if (len \|\| (flags & (TH_SYN\|TH_FIN)) \|\| tp->t_timer[TCPT_PERSIST])
513	ti->ti_seq = RT_H2N_U32(tp->snd_nxt);
514	else
515	ti->ti_seq = RT_H2N_U32(tp->snd_max);
516	ti->ti_ack = RT_H2N_U32(tp->rcv_nxt);
517	if (optlen)
518	{
519	memcpy((caddr_t)(ti + 1), (caddr_t)opt, optlen);
520	ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2;
521	}
522	ti->ti_flags = flags;
523	/*
524	* Calculate receive window. Don't shrink window,
525	* but avoid silly window syndrome.
526	*/
527	if (win < (long)(so->so_rcv.sb_datalen / 4) && win < (long)tp->t_maxseg)
528	win = 0;
529	if (win > (long)TCP_MAXWIN << tp->rcv_scale)
530	win = (long)TCP_MAXWIN << tp->rcv_scale;
531	if (win < (long)(tp->rcv_adv - tp->rcv_nxt))
532	win = (long)(tp->rcv_adv - tp->rcv_nxt);
533	ti->ti_win = RT_H2N_U16((u_int16_t) (win>>tp->rcv_scale));
534
535	#if 0
536	if (SEQ_GT(tp->snd_up, tp->snd_nxt))
537	{
538	ti->ti_urp = RT_H2N_U16((u_int16_t)(tp->snd_up - tp->snd_nxt));
539	#else
540	if (SEQ_GT(tp->snd_up, tp->snd_una))
541	{
542	ti->ti_urp = RT_H2N_U16((u_int16_t)(tp->snd_up - RT_N2H_U32(ti->ti_seq)));
543	#endif
544	ti->ti_flags \|= TH_URG;
545	}
546	else
547	/*
548	* If no urgent pointer to send, then we pull
549	* the urgent pointer to the left edge of the send window
550	* so that it doesn't drift into the send window on sequence
551	* number wraparound.
552	*/
553	tp->snd_up = tp->snd_una; /* drag it along */
554
555	/*
556	* Put TCP length in extended header, and then
557	* checksum extended header and data.
558	*/
559	if (len + optlen)
560	ti->ti_len = RT_H2N_U16((u_int16_t)(sizeof (struct tcphdr)
561	+ optlen + len));
562	ti->ti_sum = cksum(m, (int)(hdrlen + len));
563
564	/*
565	* In transmit state, time the transmission and arrange for
566	* the retransmit. In persist state, just set snd_max.
567	*/
568	if (tp->t_force == 0 \|\| tp->t_timer[TCPT_PERSIST] == 0)
569	{
570	tcp_seq startseq = tp->snd_nxt;
571
572	/*
573	* Advance snd_nxt over sequence space of this segment.
574	*/
575	if (flags & (TH_SYN\|TH_FIN))
576	{
577	if (flags & TH_SYN)
578	tp->snd_nxt++;
579	if (flags & TH_FIN)
580	{
581	tp->snd_nxt++;
582	tp->t_flags \|= TF_SENTFIN;
583	}
584	}
585	tp->snd_nxt += len;
586	if (SEQ_GT(tp->snd_nxt, tp->snd_max))
587	{
588	tp->snd_max = tp->snd_nxt;
589	/*
590	* Time this transmission if not a retransmission and
591	* not currently timing anything.
592	*/
593	if (tp->t_rtt == 0)
594	{
595	tp->t_rtt = 1;
596	tp->t_rtseq = startseq;
597	tcpstat.tcps_segstimed++;
598	}
599	}
600
601	/*
602	* Set retransmit timer if not currently set,
603	* and not doing an ack or a keep-alive probe.
604	* Initial value for retransmit timer is smoothed
605	* round-trip time + 2 * round-trip time variance.
606	* Initialize shift counter which is used for backoff
607	* of retransmit time.
608	*/
609	if ( tp->t_timer[TCPT_REXMT] == 0
610	&& tp->snd_nxt != tp->snd_una)
611	{
612	tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
613	if (tp->t_timer[TCPT_PERSIST])
614	{
615	tp->t_timer[TCPT_PERSIST] = 0;
616	tp->t_rxtshift = 0;
617	}
618	}
619	}
620	else
621	if (SEQ_GT(tp->snd_nxt + len, tp->snd_max))
622	tp->snd_max = tp->snd_nxt + len;
623
624	/*
625	* Fill in IP length and desired time to live and
626	* send to IP level. There should be a better way
627	* to handle ttl and tos; we could keep them in
628	* the template, but need a way to checksum without them.
629	*/
630	M_ASSERTPKTHDR(m);
631	m->m_pkthdr.header = mtod(m, void *);
632	m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
633
634	{
635	((struct ip *)ti)->ip_len = m->m_len;
636	((struct ip *)ti)->ip_ttl = ip_defttl;
637	((struct ip *)ti)->ip_tos = so->so_iptos;
638
639	/* #if BSD >= 43 */
640	/* Don't do IP options... */
641	#if 0
642	error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route,
643	so->so_options & SO_DONTROUTE, 0);
644	#endif
645	error = ip_output(pData, so, m);
646
647	#if 0
648	/* #else */
649	error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route,
650	so->so_options & SO_DONTROUTE);
651	/* #endif */
652	#endif
653	}
654	if (error)
655	{
656	out:
657	#if 0
658	if (error == ENOBUFS)
659	{
660	tcp_quench(tp->t_inpcb, 0);
661	return (0);
662	}
663
664	if ( ( error == EHOSTUNREACH
665	\|\| error == ENETDOWN)
666	&& TCPS_HAVERCVDSYN(tp->t_state))
667	{
668	tp->t_softerror = error;
669	return (0);
670	}
671	#endif
672	if (m != NULL)
673	m_freem(pData, m);
674	return (error);
675	}
676	tcpstat.tcps_sndtotal++;
677
678	/*
679	* Data sent (as far as we can tell).
680	* If this advertises a larger window than any other segment,
681	* then remember the size of the advertised window.
682	* Any pending ACK has now been sent.
683	*/
684	if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
685	tp->rcv_adv = tp->rcv_nxt + win;
686	tp->last_ack_sent = tp->rcv_nxt;
687	tp->t_flags &= ~(TF_ACKNOW\|TF_DELACK);
688	if (sendalot)
689	goto again;
690
691	return (0);
692	}
693
694	void
695	tcp_setpersist(struct tcpcb *tp)
696	{
697	int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
698
699	#if 0
700	if (tp->t_timer[TCPT_REXMT])
701	panic("tcp_output REXMT");
702	#endif
703	/*
704	* Start/restart persistence timer.
705	*/
706	TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
707	t * tcp_backoff[tp->t_rxtshift],
708	TCPTV_PERSMIN, TCPTV_PERSMAX);
709	if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
710	tp->t_rxtshift++;
711	}

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source: vbox/trunk/src/VBox/Devices/Network/slirp/tcp_output.c@ 30016

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