tcp_output.c revision c58f1213e628a545081c70e26c6b67a841cff880
/* $Id$ */
/** @file
* NAT - TCP output.
*/
/*
* Copyright (C) 2006-2012 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*/
/*
* This code is based on:
*
* Copyright (c) 1982, 1986, 1988, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_output.c 8.3 (Berkeley) 12/30/93
* tcp_output.c,v 1.3 1994/09/15 10:36:55 davidg Exp
*/
/*
* Changes and additions relating to SLiRP
* Copyright (c) 1995 Danny Gasparovski.
*
* Please read the file COPYRIGHT for the
* terms and conditions of the copyright.
*/
#include <slirp.h>
/*
* Since this is only used in "stats socket", we give meaning
* names instead of the REAL names
*/
const char * const tcpstates[] =
{
/* "CLOSED", "LISTEN", "SYN_SENT", "SYN_RCVD", */
"REDIRECT", "LISTEN", "SYN_SENT", "SYN_RCVD",
"ESTABLISHED", "CLOSE_WAIT", "FIN_WAIT_1", "CLOSING",
"LAST_ACK", "FIN_WAIT_2", "TIME_WAIT",
};
static const u_char tcp_outflags[TCP_NSTATES] =
{
TH_RST|TH_ACK, 0, TH_SYN, TH_SYN|TH_ACK,
TH_ACK, TH_ACK, TH_FIN|TH_ACK, TH_FIN|TH_ACK,
TH_FIN|TH_ACK, TH_ACK, TH_ACK,
};
#define MAX_TCPOPTLEN 32 /* max # bytes that go in options */
/*
* Tcp output routine: figure out what should be sent and send it.
*/
int
tcp_output(PNATState pData, register struct tcpcb *tp)
{
register struct socket *so = tp->t_socket;
register long len, win;
int off, flags, error;
register struct mbuf *m = NULL;
register struct tcpiphdr *ti;
u_char opt[MAX_TCPOPTLEN];
unsigned optlen, hdrlen;
int idle, sendalot;
int size = 0;
LogFlowFunc(("ENTER: tcp_output: tp = %R[tcpcb793]\n", tp));
/*
* Determine length of data that should be transmitted,
* and flags that will be used.
* If there is some data or critical controls (SYN, RST)
* to send, then transmit; otherwise, investigate further.
*/
idle = (tp->snd_max == tp->snd_una);
if (idle && tp->t_idle >= tp->t_rxtcur)
/*
* We have been idle for "a while" and no acks are
* expected to clock out any data we send --
* slow start to get ack "clock" running again.
*/
tp->snd_cwnd = tp->t_maxseg;
again:
sendalot = 0;
off = tp->snd_nxt - tp->snd_una;
win = min(tp->snd_wnd, tp->snd_cwnd);
flags = tcp_outflags[tp->t_state];
Log2((" --- tcp_output flags = 0x%x\n", flags));
/*
* If in persist timeout with window of 0, send 1 byte.
* Otherwise, if window is small but nonzero
* and timer expired, we will send what we can
* and go to transmit state.
*/
if (tp->t_force)
{
if (win == 0)
{
/*
* If we still have some data to send, then
* clear the FIN bit. Usually this would
* happen below when it realizes that we
* aren't sending all the data. However,
* if we have exactly 1 byte of unset data,
* then it won't clear the FIN bit below,
* and if we are in persist state, we wind
* up sending the packet without recording
* that we sent the FIN bit.
*
* We can't just blindly clear the FIN bit,
* because if we don't have any more data
* to send then the probe will be the FIN
* itself.
*/
if (off < SBUF_LEN(&so->so_snd))
flags &= ~TH_FIN;
win = 1;
}
else
{
tp->t_timer[TCPT_PERSIST] = 0;
tp->t_rxtshift = 0;
}
}
len = min(SBUF_LEN(&so->so_snd), win) - off;
if (len < 0)
{
/*
* If FIN has been sent but not acked,
* but we haven't been called to retransmit,
* len will be -1. Otherwise, window shrank
* after we sent into it. If window shrank to 0,
* cancel pending retransmit and pull snd_nxt
* back to (closed) window. We will enter persist
* state below. If the window didn't close completely,
* just wait for an ACK.
*/
len = 0;
if (win == 0)
{
tp->t_timer[TCPT_REXMT] = 0;
tp->snd_nxt = tp->snd_una;
}
}
if (len > tp->t_maxseg)
{
len = tp->t_maxseg;
sendalot = 1;
}
if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + SBUF_LEN(&so->so_snd)))
flags &= ~TH_FIN;
win = sbspace(&so->so_rcv);
/*
* Sender silly window avoidance. If connection is idle
* and can send all data, a maximum segment,
* at least a maximum default-size segment do it,
* or are forced, do it; otherwise don't bother.
* If peer's buffer is tiny, then send
* when window is at least half open.
* If retransmitting (possibly after persist timer forced us
* to send into a small window), then must resend.
*/
if (len)
{
if (len == tp->t_maxseg)
goto send;
if ((1 || idle || tp->t_flags & TF_NODELAY) &&
len + off >= SBUF_LEN(&so->so_snd))
goto send;
if (tp->t_force)
goto send;
if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
goto send;
if (SEQ_LT(tp->snd_nxt, tp->snd_max))
goto send;
}
/*
* Compare available window to amount of window
* known to peer (as advertised window less
* next expected input). If the difference is at least two
* max size segments, or at least 50% of the maximum possible
* window, then want to send a window update to peer.
*/
if (win > 0)
{
/*
* "adv" is the amount we can increase the window,
* taking into account that we are limited by
* TCP_MAXWIN << tp->rcv_scale.
*/
long adv = min(win,
(long)TCP_MAXWIN << tp->rcv_scale) -
(tp->rcv_adv - tp->rcv_nxt);
if (adv >= (long) (2 * tp->t_maxseg))
goto send;
if (2 * adv >= (long) SBUF_SIZE(&so->so_rcv))
goto send;
}
/*
* Send if we owe peer an ACK.
*/
if (tp->t_flags & TF_ACKNOW)
goto send;
if (flags & (TH_SYN|TH_RST))
goto send;
if (SEQ_GT(tp->snd_up, tp->snd_una))
goto send;
/*
* If our state indicates that FIN should be sent
* and we have not yet done so, or we're retransmitting the FIN,
* then we need to send.
*/
if ( flags & TH_FIN
&& ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una))
goto send;
/*
* TCP window updates are not reliable, rather a polling protocol
* using ``persist'' packets is used to insure receipt of window
* updates. The three ``states'' for the output side are:
* idle not doing retransmits or persists
* persisting to move a small or zero window
* (re)transmitting and thereby not persisting
*
* tp->t_timer[TCPT_PERSIST]
* is set when we are in persist state.
* tp->t_force
* is set when we are called to send a persist packet.
* tp->t_timer[TCPT_REXMT]
* is set when we are retransmitting
* The output side is idle when both timers are zero.
*
* If send window is too small, there is data to transmit, and no
* retransmit or persist is pending, then go to persist state.
* If nothing happens soon, send when timer expires:
* if window is nonzero, transmit what we can,
* otherwise force out a byte.
*/
if ( SBUF_LEN(&so->so_snd)
&& tp->t_timer[TCPT_REXMT] == 0
&& tp->t_timer[TCPT_PERSIST] == 0)
{
tp->t_rxtshift = 0;
tcp_setpersist(tp);
}
/*
* No reason to send a segment, just return.
*/
tcpstat.tcps_didnuttin++;
LogFlowFuncLeave();
return (0);
send:
LogFlowFunc(("send\n"));
/*
* Before ESTABLISHED, force sending of initial options
* unless TCP set not to do any options.
* NOTE: we assume that the IP/TCP header plus TCP options
* always fit in a single mbuf, leaving room for a maximum
* link header, i.e.
* max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MHLEN
*/
optlen = 0;
hdrlen = sizeof (struct tcpiphdr);
if (flags & TH_SYN)
{
tp->snd_nxt = tp->iss;
if ((tp->t_flags & TF_NOOPT) == 0)
{
u_int16_t mss;
opt[0] = TCPOPT_MAXSEG;
opt[1] = 4;
mss = RT_H2N_U16((u_int16_t) tcp_mss(pData, tp, 0));
memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss));
optlen = 4;
#if 0
if ( (tp->t_flags & TF_REQ_SCALE)
&& ( (flags & TH_ACK) == 0
|| (tp->t_flags & TF_RCVD_SCALE)))
{
*((u_int32_t *) (opt + optlen)) = RT_H2N_U32( TCPOPT_NOP << 24
| TCPOPT_WINDOW << 16
| TCPOLEN_WINDOW << 8
| tp->request_r_scale);
optlen += 4;
}
#endif
}
}
/*
* Send a timestamp and echo-reply if this is a SYN and our side
* wants to use timestamps (TF_REQ_TSTMP is set) or both our side
* and our peer have sent timestamps in our SYN's.
*/
#if 0
if ( (tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP
&& (flags & TH_RST) == 0
&& ( (flags & (TH_SYN|TH_ACK)) == TH_SYN
|| (tp->t_flags & TF_RCVD_TSTMP)))
{
u_int32_t *lp = (u_int32_t *)(opt + optlen);
/* Form timestamp option as shown in appendix A of RFC 1323. */
*lp++ = RT_H2N_U32_C(TCPOPT_TSTAMP_HDR);
*lp++ = RT_H2N_U32(tcp_now);
*lp = RT_H2N_U32(tp->ts_recent);
optlen += TCPOLEN_TSTAMP_APPA;
}
#endif
hdrlen += optlen;
/*
* Adjust data length if insertion of options will
* bump the packet length beyond the t_maxseg length.
*/
if (len > tp->t_maxseg - optlen)
{
len = tp->t_maxseg - optlen;
sendalot = 1;
}
/*
* Grab a header mbuf, attaching a copy of data to
* be transmitted, and initialize the header from
* the template for sends on this connection.
*/
if (len)
{
if (tp->t_force && len == 1)
tcpstat.tcps_sndprobe++;
else if (SEQ_LT(tp->snd_nxt, tp->snd_max))
{
tcpstat.tcps_sndrexmitpack++;
tcpstat.tcps_sndrexmitbyte += len;
}
else
{
tcpstat.tcps_sndpack++;
tcpstat.tcps_sndbyte += len;
}
size = MCLBYTES;
if ((len + hdrlen + ETH_HLEN) < MSIZE)
size = MCLBYTES;
else if ((len + hdrlen + ETH_HLEN) < MCLBYTES)
size = MCLBYTES;
else if((len + hdrlen + ETH_HLEN) < MJUM9BYTES)
size = MJUM9BYTES;
else if ((len + hdrlen + ETH_HLEN) < MJUM16BYTES)
size = MJUM16BYTES;
else
AssertMsgFailed(("Unsupported size"));
m = m_getjcl(pData, M_NOWAIT, MT_HEADER, M_PKTHDR, size);
if (m == NULL)
{
/* error = ENOBUFS; */
error = 1;
goto out;
}
m->m_data += if_maxlinkhdr;
m->m_pkthdr.header = mtod(m, void *);
m->m_len = hdrlen;
/*
* This will always succeed, since we make sure our mbufs
* are big enough to hold one MSS packet + header + ... etc.
*/
#if 0
if (len <= MHLEN - hdrlen - max_linkhdr)
{
#endif
#ifndef VBOX_WITH_SLIRP_BSD_SBUF
sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
m->m_len += len;
#else
m_copyback(pData, m, hdrlen, len, sbuf_data(&so->so_snd) + off);
#endif
#if 0
}
else
{
m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len);
if (m->m_next == 0)
len = 0;
}
#endif
/*
* If we're sending everything we've got, set PUSH.
* (This will keep happy those implementations which only
* give data to the user when a buffer fills or
* a PUSH comes in.)
*/
if (off + len == SBUF_LEN(&so->so_snd))
flags |= TH_PUSH;
}
else
{
bool fUninitiolizedTemplate = false;
if (tp->t_flags & TF_ACKNOW)
tcpstat.tcps_sndacks++;
else if (flags & (TH_SYN|TH_FIN|TH_RST))
tcpstat.tcps_sndctrl++;
else if (SEQ_GT(tp->snd_up, tp->snd_una))
tcpstat.tcps_sndurg++;
else
tcpstat.tcps_sndwinup++;
if ((hdrlen + ETH_HLEN) < MSIZE)
{
size = MCLBYTES;
}
else if ((hdrlen + ETH_HLEN) < MCLBYTES)
{
size = MCLBYTES;
}
else if((hdrlen + ETH_HLEN) < MJUM9BYTES)
{
size = MJUM9BYTES;
}
else if ((hdrlen + ETH_HLEN) < MJUM16BYTES)
{
size = MJUM16BYTES;
}
else
{
AssertMsgFailed(("Unsupported size"));
}
m = m_getjcl(pData, M_NOWAIT, MT_HEADER, M_PKTHDR, size);
if (m == NULL)
{
/* error = ENOBUFS; */
error = 1;
goto out;
}
m->m_data += if_maxlinkhdr;
m->m_pkthdr.header = mtod(m, void *);
m->m_len = hdrlen;
/*
* Uninitialized TCP template looks very suspicious at this processing state, thus why we have
* to workaround the problem till right fix. Warning appears once at release log.
*/
fUninitiolizedTemplate = RT_BOOL(( tp->t_template.ti_src.s_addr == INADDR_ANY
|| tp->t_template.ti_dst.s_addr == INADDR_ANY));
#ifndef DEBUG_vvl
if (fUninitiolizedTemplate)
{
static bool fWarn;
tcp_template(tp);
if(!fWarn)
{
LogRel(("NAT:TCP: TCP template was created forcely from socket information\n"));
fWarn = true;
}
}
#else
Assert((!fUninitiolizedTemplate));
#endif
}
ti = mtod(m, struct tcpiphdr *);
memcpy((caddr_t)ti, &tp->t_template, sizeof (struct tcpiphdr));
/*
* Fill in fields, remembering maximum advertised
* window for use in delaying messages about window sizes.
* If resending a FIN, be sure not to use a new sequence number.
*/
if ( flags & TH_FIN
&& tp->t_flags & TF_SENTFIN
&& tp->snd_nxt == tp->snd_max)
tp->snd_nxt--;
/*
* If we are doing retransmissions, then snd_nxt will
* not reflect the first unsent octet. For ACK only
* packets, we do not want the sequence number of the
* retransmitted packet, we want the sequence number
* of the next unsent octet. So, if there is no data
* (and no SYN or FIN), use snd_max instead of snd_nxt
* when filling in ti_seq. But if we are in persist
* state, snd_max might reflect one byte beyond the
* right edge of the window, so use snd_nxt in that
* case, since we know we aren't doing a retransmission.
* (retransmit and persist are mutually exclusive...)
*/
if (len || (flags & (TH_SYN|TH_FIN)) || tp->t_timer[TCPT_PERSIST])
ti->ti_seq = RT_H2N_U32(tp->snd_nxt);
else
ti->ti_seq = RT_H2N_U32(tp->snd_max);
ti->ti_ack = RT_H2N_U32(tp->rcv_nxt);
if (optlen)
{
memcpy((caddr_t)(ti + 1), (caddr_t)opt, optlen);
ti->ti_off = (sizeof (struct tcphdr) + optlen) >> 2;
}
ti->ti_flags = flags;
/*
* Calculate receive window. Don't shrink window,
* but avoid silly window syndrome.
*/
if (win < (long)(SBUF_SIZE(&so->so_rcv) / 4) && win < (long)tp->t_maxseg)
win = 0;
if (win > (long)TCP_MAXWIN << tp->rcv_scale)
win = (long)TCP_MAXWIN << tp->rcv_scale;
if (win < (long)(tp->rcv_adv - tp->rcv_nxt))
win = (long)(tp->rcv_adv - tp->rcv_nxt);
ti->ti_win = RT_H2N_U16((u_int16_t) (win>>tp->rcv_scale));
#if 0
if (SEQ_GT(tp->snd_up, tp->snd_nxt))
{
ti->ti_urp = RT_H2N_U16((u_int16_t)(tp->snd_up - tp->snd_nxt));
#else
if (SEQ_GT(tp->snd_up, tp->snd_una))
{
ti->ti_urp = RT_H2N_U16((u_int16_t)(tp->snd_up - RT_N2H_U32(ti->ti_seq)));
#endif
ti->ti_flags |= TH_URG;
}
else
/*
* If no urgent pointer to send, then we pull
* the urgent pointer to the left edge of the send window
* so that it doesn't drift into the send window on sequence
* number wraparound.
*/
tp->snd_up = tp->snd_una; /* drag it along */
/*
* Put TCP length in extended header, and then
* checksum extended header and data.
*/
if (len + optlen)
ti->ti_len = RT_H2N_U16((u_int16_t)(sizeof (struct tcphdr)
+ optlen + len));
ti->ti_sum = cksum(m, (int)(hdrlen + len));
/*
* In transmit state, time the transmission and arrange for
* the retransmit. In persist state, just set snd_max.
*/
if (tp->t_force == 0 || tp->t_timer[TCPT_PERSIST] == 0)
{
tcp_seq startseq = tp->snd_nxt;
/*
* Advance snd_nxt over sequence space of this segment.
*/
if (flags & (TH_SYN|TH_FIN))
{
if (flags & TH_SYN)
tp->snd_nxt++;
if (flags & TH_FIN)
{
tp->snd_nxt++;
tp->t_flags |= TF_SENTFIN;
}
}
tp->snd_nxt += len;
if (SEQ_GT(tp->snd_nxt, tp->snd_max))
{
tp->snd_max = tp->snd_nxt;
/*
* Time this transmission if not a retransmission and
* not currently timing anything.
*/
if (tp->t_rtt == 0)
{
tp->t_rtt = 1;
tp->t_rtseq = startseq;
tcpstat.tcps_segstimed++;
}
}
/*
* Set retransmit timer if not currently set,
* and not doing an ack or a keep-alive probe.
* Initial value for retransmit timer is smoothed
* round-trip time + 2 * round-trip time variance.
* Initialize shift counter which is used for backoff
* of retransmit time.
*/
if ( tp->t_timer[TCPT_REXMT] == 0
&& tp->snd_nxt != tp->snd_una)
{
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
if (tp->t_timer[TCPT_PERSIST])
{
tp->t_timer[TCPT_PERSIST] = 0;
tp->t_rxtshift = 0;
}
}
}
else
if (SEQ_GT(tp->snd_nxt + len, tp->snd_max))
tp->snd_max = tp->snd_nxt + len;
/*
* Fill in IP length and desired time to live and
* send to IP level. There should be a better way
* to handle ttl and tos; we could keep them in
* the template, but need a way to checksum without them.
*/
M_ASSERTPKTHDR(m);
m->m_pkthdr.header = mtod(m, void *);
m->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
{
((struct ip *)ti)->ip_len = m->m_len;
((struct ip *)ti)->ip_ttl = ip_defttl;
((struct ip *)ti)->ip_tos = so->so_iptos;
/* #if BSD >= 43 */
/* Don't do IP options... */
#if 0
error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route,
so->so_options & SO_DONTROUTE, 0);
#endif
error = ip_output(pData, so, m);
#if 0
/* #else */
error = ip_output(m, (struct mbuf *)0, &tp->t_inpcb->inp_route,
so->so_options & SO_DONTROUTE);
/* #endif */
#endif
}
if (error)
{
out:
#if 0
if (error == ENOBUFS)
{
tcp_quench(tp->t_inpcb, 0);
return (0);
}
if ( ( error == EHOSTUNREACH
|| error == ENETDOWN)
&& TCPS_HAVERCVDSYN(tp->t_state))
{
tp->t_softerror = error;
return (0);
}
#endif
if (m != NULL)
m_freem(pData, m);
return (error);
}
tcpstat.tcps_sndtotal++;
/*
* Data sent (as far as we can tell).
* If this advertises a larger window than any other segment,
* then remember the size of the advertised window.
* Any pending ACK has now been sent.
*/
if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv))
tp->rcv_adv = tp->rcv_nxt + win;
tp->last_ack_sent = tp->rcv_nxt;
tp->t_flags &= ~(TF_ACKNOW|TF_DELACK);
if (sendalot)
goto again;
return (0);
}
void
tcp_setpersist(struct tcpcb *tp)
{
int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
#if 0
if (tp->t_timer[TCPT_REXMT])
panic("tcp_output REXMT");
#endif
/*
* Start/restart persistence timer.
*/
TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
t * tcp_backoff[tp->t_rxtshift],
TCPTV_PERSMIN, TCPTV_PERSMAX);
if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
tp->t_rxtshift++;
}