tcp_output.c@ 35922

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1	/* $Id: tcp_output.c 35163 2010-12-16 07:37:00Z 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 = 0;
103
104	LogFlow(("tcp_output: tp = %lx\n", (long)tp));
105
106	/*
107	* Determine length of data that should be transmitted,
108	* and flags that will be used.
109	* If there is some data or critical controls (SYN, RST)
110	* to send, then transmit; otherwise, investigate further.
111	*/
112	idle = (tp->snd_max == tp->snd_una);
113	if (idle && tp->t_idle >= tp->t_rxtcur)
114	/*
115	* We have been idle for "a while" and no acks are
116	* expected to clock out any data we send --
117	* slow start to get ack "clock" running again.
118	*/
119	tp->snd_cwnd = tp->t_maxseg;
120
121	again:
122	sendalot = 0;
123	off = tp->snd_nxt - tp->snd_una;
124	win = min(tp->snd_wnd, tp->snd_cwnd);
125
126	flags = tcp_outflags[tp->t_state];
127
128	Log2((" --- tcp_output flags = 0x%x\n", flags));
129
130	/*
131	* If in persist timeout with window of 0, send 1 byte.
132	* Otherwise, if window is small but nonzero
133	* and timer expired, we will send what we can
134	* and go to transmit state.
135	*/
136	if (tp->t_force)
137	{
138	if (win == 0)
139	{
140	/*
141	* If we still have some data to send, then
142	* clear the FIN bit. Usually this would
143	* happen below when it realizes that we
144	* aren't sending all the data. However,
145	* if we have exactly 1 byte of unset data,
146	* then it won't clear the FIN bit below,
147	* and if we are in persist state, we wind
148	* up sending the packet without recording
149	* that we sent the FIN bit.
150	*
151	* We can't just blindly clear the FIN bit,
152	* because if we don't have any more data
153	* to send then the probe will be the FIN
154	* itself.
155	*/
156	if (off < SBUF_LEN(&so->so_snd))
157	flags &= ~TH_FIN;
158	win = 1;
159	}
160	else
161	{
162	tp->t_timer[TCPT_PERSIST] = 0;
163	tp->t_rxtshift = 0;
164	}
165	}
166
167	len = min(SBUF_LEN(&so->so_snd), win) - off;
168	if (len < 0)
169	{
170	/*
171	* If FIN has been sent but not acked,
172	* but we haven't been called to retransmit,
173	* len will be -1. Otherwise, window shrank
174	* after we sent into it. If window shrank to 0,
175	* cancel pending retransmit and pull snd_nxt
176	* back to (closed) window. We will enter persist
177	* state below. If the window didn't close completely,
178	* just wait for an ACK.
179	*/
180	len = 0;
181	if (win == 0)
182	{
183	tp->t_timer[TCPT_REXMT] = 0;
184	tp->snd_nxt = tp->snd_una;
185	}
186	}
187	if (len > tp->t_maxseg)
188	{
189	len = tp->t_maxseg;
190	sendalot = 1;
191	}
192	if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + SBUF_LEN(&so->so_snd)))
193	flags &= ~TH_FIN;
194
195	win = sbspace(&so->so_rcv);
196
197	/*
198	* Sender silly window avoidance. If connection is idle
199	* and can send all data, a maximum segment,
200	* at least a maximum default-size segment do it,
201	* or are forced, do it; otherwise don't bother.
202	* If peer's buffer is tiny, then send
203	* when window is at least half open.
204	* If retransmitting (possibly after persist timer forced us
205	* to send into a small window), then must resend.
206	*/
207	if (len)
208	{
209	if (len == tp->t_maxseg)
210	goto send;
211	if ((1 \|\| idle \|\| tp->t_flags & TF_NODELAY) &&
212	len + off >= SBUF_LEN(&so->so_snd))
213	goto send;
214	if (tp->t_force)
215	goto send;
216	if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
217	goto send;
218	if (SEQ_LT(tp->snd_nxt, tp->snd_max))
219	goto send;
220	}
221
222	/*
223	* Compare available window to amount of window
224	* known to peer (as advertised window less
225	* next expected input). If the difference is at least two
226	* max size segments, or at least 50% of the maximum possible
227	* window, then want to send a window update to peer.
228	*/
229	if (win > 0)
230	{
231	/*
232	* "adv" is the amount we can increase the window,
233	* taking into account that we are limited by
234	* TCP_MAXWIN << tp->rcv_scale.
235	*/
236	long adv = min(win,
237	(long)TCP_MAXWIN << tp->rcv_scale) -
238	(tp->rcv_adv - tp->rcv_nxt);
239
240	if (adv >= (long) (2 * tp->t_maxseg))
241	goto send;
242	if (2 * adv >= (long) SBUF_SIZE(&so->so_rcv))
243	goto send;
244	}
245
246	/*
247	* Send if we owe peer an ACK.
248	*/
249	if (tp->t_flags & TF_ACKNOW)
250	goto send;
251	if (flags & (TH_SYN\|TH_RST))
252	goto send;
253	if (SEQ_GT(tp->snd_up, tp->snd_una))
254	goto send;
255	/*
256	* If our state indicates that FIN should be sent
257	* and we have not yet done so, or we're retransmitting the FIN,
258	* then we need to send.
259	*/
260	if ( flags & TH_FIN
261	&& ((tp->t_flags & TF_SENTFIN) == 0 \|\| tp->snd_nxt == tp->snd_una))
262	goto send;
263
264	/*
265	* TCP window updates are not reliable, rather a polling protocol
266	* using ``persist'' packets is used to insure receipt of window
267	* updates. The three ``states'' for the output side are:
268	* idle not doing retransmits or persists
269	* persisting to move a small or zero window
270	* (re)transmitting and thereby not persisting
271	*
272	* tp->t_timer[TCPT_PERSIST]
273	* is set when we are in persist state.
274	* tp->t_force
275	* is set when we are called to send a persist packet.
276	* tp->t_timer[TCPT_REXMT]
277	* is set when we are retransmitting
278	* The output side is idle when both timers are zero.
279	*
280	* If send window is too small, there is data to transmit, and no
281	* retransmit or persist is pending, then go to persist state.
282	* If nothing happens soon, send when timer expires:
283	* if window is nonzero, transmit what we can,
284	* otherwise force out a byte.
285	*/
286	if ( SBUF_LEN(&so->so_snd)
287	&& tp->t_timer[TCPT_REXMT] == 0
288	&& tp->t_timer[TCPT_PERSIST] == 0)
289	{
290	tp->t_rxtshift = 0;
291	tcp_setpersist(tp);
292	}
293
294	/*
295	* No reason to send a segment, just return.
296	*/
297	tcpstat.tcps_didnuttin++;
298
299	return (0);
300
301	send:
302	/*
303	* Before ESTABLISHED, force sending of initial options
304	* unless TCP set not to do any options.
305	* NOTE: we assume that the IP/TCP header plus TCP options
306	* always fit in a single mbuf, leaving room for a maximum
307	* link header, i.e.
308	* max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MHLEN
309	*/
310	optlen = 0;
311	hdrlen = sizeof (struct tcpiphdr);
312	if (flags & TH_SYN)
313	{
314	tp->snd_nxt = tp->iss;
315	if ((tp->t_flags & TF_NOOPT) == 0)
316	{
317	u_int16_t mss;
318
319	opt[0] = TCPOPT_MAXSEG;
320	opt[1] = 4;
321	mss = RT_H2N_U16((u_int16_t) tcp_mss(pData, tp, 0));
322	memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss));
323	optlen = 4;
324
325	#if 0
326	if ( (tp->t_flags & TF_REQ_SCALE)
327	&& ( (flags & TH_ACK) == 0
328	\|\| (tp->t_flags & TF_RCVD_SCALE)))
329	{
330	((u_int32_t ) (opt + optlen)) = RT_H2N_U32( TCPOPT_NOP << 24
331	\| TCPOPT_WINDOW << 16
332	\| TCPOLEN_WINDOW << 8
333	\| tp->request_r_scale);
334	optlen += 4;
335	}
336	#endif
337	}
338	}
339
340	/*
341	* Send a timestamp and echo-reply if this is a SYN and our side
342	* wants to use timestamps (TF_REQ_TSTMP is set) or both our side
343	* and our peer have sent timestamps in our SYN's.
344	*/
345	#if 0
346	if ( (tp->t_flags & (TF_REQ_TSTMP\|TF_NOOPT)) == TF_REQ_TSTMP
347	&& (flags & TH_RST) == 0
348	&& ( (flags & (TH_SYN\|TH_ACK)) == TH_SYN
349	\|\| (tp->t_flags & TF_RCVD_TSTMP)))
350	{
351	u_int32_t lp = (u_int32_t )(opt + optlen);
352
353	/* Form timestamp option as shown in appendix A of RFC 1323. */
354	*lp++ = RT_H2N_U32_C(TCPOPT_TSTAMP_HDR);
355	*lp++ = RT_H2N_U32(tcp_now);
356	*lp = RT_H2N_U32(tp->ts_recent);
357	optlen += TCPOLEN_TSTAMP_APPA;
358	}
359	#endif
360	hdrlen += optlen;
361
362	/*
363	* Adjust data length if insertion of options will
364	* bump the packet length beyond the t_maxseg length.
365	*/
366	if (len > tp->t_maxseg - optlen)
367	{
368	len = tp->t_maxseg - optlen;
369	sendalot = 1;
370	}
371
372	/*
373	* Grab a header mbuf, attaching a copy of data to
374	* be transmitted, and initialize the header from
375	* the template for sends on this connection.
376	*/
377	if (len)
378	{
379	if (tp->t_force && len == 1)
380	tcpstat.tcps_sndprobe++;
381	else if (SEQ_LT(tp->snd_nxt, tp->snd_max))
382	{
383	tcpstat.tcps_sndrexmitpack++;
384	tcpstat.tcps_sndrexmitbyte += len;
385	}
386	else
387	{
388	tcpstat.tcps_sndpack++;
389	tcpstat.tcps_sndbyte += len;
390	}
391
392	size = MCLBYTES;
393	if ((len + hdrlen + ETH_HLEN) < MSIZE)
394	size = MCLBYTES;
395	else if ((len + hdrlen + ETH_HLEN) < MCLBYTES)
396	size = MCLBYTES;
397	else if((len + hdrlen + ETH_HLEN) < MJUM9BYTES)
398	size = MJUM9BYTES;
399	else if ((len + hdrlen + ETH_HLEN) < MJUM16BYTES)
400	size = MJUM16BYTES;
401	else
402	AssertMsgFailed(("Unsupported size"));
403	m = m_getjcl(pData, M_NOWAIT, MT_HEADER, M_PKTHDR, size);
404	if (m == NULL)
405	{
406	/* error = ENOBUFS; */
407	error = 1;
408	goto out;
409	}
410	m->m_data += if_maxlinkhdr;
411	m->m_pkthdr.header = mtod(m, void *);
412	m->m_len = hdrlen;
413
414	/*
415	* This will always succeed, since we make sure our mbufs
416	* are big enough to hold one MSS packet + header + ... etc.
417	*/
418	#if 0
419	if (len <= MHLEN - hdrlen - max_linkhdr)
420	{
421	#endif
422	#ifndef VBOX_WITH_SLIRP_BSD_SBUF
423	sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
424	m->m_len += len;
425	#else
426	m_copyback(pData, m, hdrlen, len, sbuf_data(&so->so_snd) + off);
427	#endif
428	#if 0
429	}
430	else
431	{
432	m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
433	if (m->m_next == 0)
434	len = 0;
435	}
436	#endif
437	/*
438	* If we're sending everything we've got, set PUSH.
439	* (This will keep happy those implementations which only
440	* give data to the user when a buffer fills or
441	* a PUSH comes in.)
442	*/
443	if (off + len == SBUF_LEN(&so->so_snd))
444	flags \|= TH_PUSH;
445	}
446	else
447	{
448	if (tp->t_flags & TF_ACKNOW)
449	tcpstat.tcps_sndacks++;
450	else if (flags & (TH_SYN\|TH_FIN\|TH_RST))
451	tcpstat.tcps_sndctrl++;
452	else if (SEQ_GT(tp->snd_up, tp->snd_una))
453	tcpstat.tcps_sndurg++;
454	else
455	tcpstat.tcps_sndwinup++;
456
457	if ((hdrlen + ETH_HLEN) < MSIZE)
458	{
459	size = MCLBYTES;
460	}
461	else if ((hdrlen + ETH_HLEN) < MCLBYTES)
462	{
463	size = MCLBYTES;
464	}
465	else if((hdrlen + ETH_HLEN) < MJUM9BYTES)
466	{
467	size = MJUM9BYTES;
468	}
469	else if ((hdrlen + ETH_HLEN) < MJUM16BYTES)
470	{
471	size = MJUM16BYTES;
472	}
473	else
474	{
475	AssertMsgFailed(("Unsupported size"));
476	}
477	m = m_getjcl(pData, M_NOWAIT, MT_HEADER, M_PKTHDR, size);
478	if (m == NULL)
479	{
480	/* error = ENOBUFS; */
481	error = 1;
482	goto out;
483	}
484	m->m_data += if_maxlinkhdr;
485	m->m_pkthdr.header = mtod(m, void *);
486	m->m_len = hdrlen;
487	}
488
489	ti = mtod(m, struct tcpiphdr *);
490
491	memcpy((caddr_t)ti, &tp->t_template, sizeof (struct tcpiphdr));
492
493	/*
494	* Fill in fields, remembering maximum advertised
495	* window for use in delaying messages about window sizes.
496	* If resending a FIN, be sure not to use a new sequence number.
497	*/
498	if ( flags & TH_FIN
499	&& tp->t_flags & TF_SENTFIN
500	&& tp->snd_nxt == tp->snd_max)
501	tp->snd_nxt--;
502	/*
503	* If we are doing retransmissions, then snd_nxt will
504	* not reflect the first unsent octet. For ACK only
505	* packets, we do not want the sequence number of the
506	* retransmitted packet, we want the sequence number
507	* of the next unsent octet. So, if there is no data
508	* (and no SYN or FIN), use snd_max instead of snd_nxt
509	* when filling in ti_seq. But if we are in persist
510	* state, snd_max might reflect one byte beyond the
511	* right edge of the window, so use snd_nxt in that
512	* case, since we know we aren't doing a retransmission.
513	* (retransmit and persist are mutually exclusive...)
514	*/
515	if (len \|\| (flags & (TH_SYN\|TH_FIN)) \|\| tp->t_timer[TCPT_PERSIST])
516	ti->ti_seq = RT_H2N_U32(tp->snd_nxt);
517	else
518	ti->ti_seq = RT_H2N_U32(tp->snd_max);
519	ti->ti_ack = RT_H2N_U32(tp->rcv_nxt);
520	if (optlen)
521	{
522	memcpy((caddr_t)(ti + 1), (caddr_t)opt, optlen);
523	ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2;
524	}
525	ti->ti_flags = flags;
526	/*
527	* Calculate receive window. Don't shrink window,
528	* but avoid silly window syndrome.
529	*/
530	if (win < (long)(SBUF_SIZE(&so->so_rcv) / 4) && win < (long)tp->t_maxseg)
531	win = 0;
532	if (win > (long)TCP_MAXWIN << tp->rcv_scale)
533	win = (long)TCP_MAXWIN << tp->rcv_scale;
534	if (win < (long)(tp->rcv_adv - tp->rcv_nxt))
535	win = (long)(tp->rcv_adv - tp->rcv_nxt);
536	ti->ti_win = RT_H2N_U16((u_int16_t) (win>>tp->rcv_scale));
537
538	#if 0
539	if (SEQ_GT(tp->snd_up, tp->snd_nxt))
540	{
541	ti->ti_urp = RT_H2N_U16((u_int16_t)(tp->snd_up - tp->snd_nxt));
542	#else
543	if (SEQ_GT(tp->snd_up, tp->snd_una))
544	{
545	ti->ti_urp = RT_H2N_U16((u_int16_t)(tp->snd_up - RT_N2H_U32(ti->ti_seq)));
546	#endif
547	ti->ti_flags \|= TH_URG;
548	}
549	else
550	/*
551	* If no urgent pointer to send, then we pull
552	* the urgent pointer to the left edge of the send window
553	* so that it doesn't drift into the send window on sequence
554	* number wraparound.
555	*/
556	tp->snd_up = tp->snd_una; /* drag it along */
557
558	/*
559	* Put TCP length in extended header, and then
560	* checksum extended header and data.
561	*/
562	if (len + optlen)
563	ti->ti_len = RT_H2N_U16((u_int16_t)(sizeof (struct tcphdr)
564	+ optlen + len));
565	ti->ti_sum = cksum(m, (int)(hdrlen + len));
566
567	/*
568	* In transmit state, time the transmission and arrange for
569	* the retransmit. In persist state, just set snd_max.
570	*/
571	if (tp->t_force == 0 \|\| tp->t_timer[TCPT_PERSIST] == 0)
572	{
573	tcp_seq startseq = tp->snd_nxt;
574
575	/*
576	* Advance snd_nxt over sequence space of this segment.
577	*/
578	if (flags & (TH_SYN\|TH_FIN))
579	{
580	if (flags & TH_SYN)
581	tp->snd_nxt++;
582	if (flags & TH_FIN)
583	{
584	tp->snd_nxt++;
585	tp->t_flags \|= TF_SENTFIN;
586	}
587	}
588	tp->snd_nxt += len;
589	if (SEQ_GT(tp->snd_nxt, tp->snd_max))
590	{
591	tp->snd_max = tp->snd_nxt;
592	/*
593	* Time this transmission if not a retransmission and
594	* not currently timing anything.
595	*/
596	if (tp->t_rtt == 0)
597	{
598	tp->t_rtt = 1;
599	tp->t_rtseq = startseq;
600	tcpstat.tcps_segstimed++;
601	}
602	}
603
604	/*
605	* Set retransmit timer if not currently set,
606	* and not doing an ack or a keep-alive probe.
607	* Initial value for retransmit timer is smoothed
608	* round-trip time + 2 * round-trip time variance.
609	* Initialize shift counter which is used for backoff
610	* of retransmit time.
611	*/
612	if ( tp->t_timer[TCPT_REXMT] == 0
613	&& tp->snd_nxt != tp->snd_una)
614	{
615	tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
616	if (tp->t_timer[TCPT_PERSIST])
617	{
618	tp->t_timer[TCPT_PERSIST] = 0;
619	tp->t_rxtshift = 0;
620	}
621	}
622	}
623	else
624	if (SEQ_GT(tp->snd_nxt + len, tp->snd_max))
625	tp->snd_max = tp->snd_nxt + len;
626
627	/*
628	* Fill in IP length and desired time to live and
629	* send to IP level. There should be a better way
630	* to handle ttl and tos; we could keep them in
631	* the template, but need a way to checksum without them.
632	*/
633	M_ASSERTPKTHDR(m);
634	m->m_pkthdr.header = mtod(m, void *);
635	m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
636
637	{
638	((struct ip *)ti)->ip_len = m->m_len;
639	((struct ip *)ti)->ip_ttl = ip_defttl;
640	((struct ip *)ti)->ip_tos = so->so_iptos;
641
642	/* #if BSD >= 43 */
643	/* Don't do IP options... */
644	#if 0
645	error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route,
646	so->so_options & SO_DONTROUTE, 0);
647	#endif
648	error = ip_output(pData, so, m);
649
650	#if 0
651	/* #else */
652	error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route,
653	so->so_options & SO_DONTROUTE);
654	/* #endif */
655	#endif
656	}
657	if (error)
658	{
659	out:
660	#if 0
661	if (error == ENOBUFS)
662	{
663	tcp_quench(tp->t_inpcb, 0);
664	return (0);
665	}
666
667	if ( ( error == EHOSTUNREACH
668	\|\| error == ENETDOWN)
669	&& TCPS_HAVERCVDSYN(tp->t_state))
670	{
671	tp->t_softerror = error;
672	return (0);
673	}
674	#endif
675	if (m != NULL)
676	m_freem(pData, m);
677	return (error);
678	}
679	tcpstat.tcps_sndtotal++;
680
681	/*
682	* Data sent (as far as we can tell).
683	* If this advertises a larger window than any other segment,
684	* then remember the size of the advertised window.
685	* Any pending ACK has now been sent.
686	*/
687	if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
688	tp->rcv_adv = tp->rcv_nxt + win;
689	tp->last_ack_sent = tp->rcv_nxt;
690	tp->t_flags &= ~(TF_ACKNOW\|TF_DELACK);
691	if (sendalot)
692	goto again;
693
694	return (0);
695	}
696
697	void
698	tcp_setpersist(struct tcpcb *tp)
699	{
700	int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
701
702	#if 0
703	if (tp->t_timer[TCPT_REXMT])
704	panic("tcp_output REXMT");
705	#endif
706	/*
707	* Start/restart persistence timer.
708	*/
709	TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
710	t * tcp_backoff[tp->t_rxtshift],
711	TCPTV_PERSMIN, TCPTV_PERSMAX);
712	if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
713	tp->t_rxtshift++;
714	}

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source: vbox/trunk/src/VBox/Devices/Network/slirp/tcp_output.c@ 35922

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