This commit is contained in:
commit
b6b7d72717
96 changed files with 37739 additions and 0 deletions
492
slirp/tcp_output.c
Normal file
492
slirp/tcp_output.c
Normal file
|
|
@ -0,0 +1,492 @@
|
|||
/*
|
||||
* 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. 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"
|
||||
|
||||
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(struct tcpcb *tp)
|
||||
{
|
||||
register struct socket *so = tp->t_socket;
|
||||
register long len, win;
|
||||
int off, flags, error;
|
||||
register struct mbuf *m;
|
||||
register struct tcpiphdr *ti;
|
||||
u_char opt[MAX_TCPOPTLEN];
|
||||
unsigned optlen, hdrlen;
|
||||
int idle, sendalot;
|
||||
|
||||
DEBUG_CALL("tcp_output");
|
||||
DEBUG_ARG("tp = %lx", (long )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];
|
||||
|
||||
DEBUG_MISC((dfd, " --- 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 < so->so_snd.sb_cc)
|
||||
flags &= ~TH_FIN;
|
||||
win = 1;
|
||||
} else {
|
||||
tp->t_timer[TCPT_PERSIST] = 0;
|
||||
tp->t_rxtshift = 0;
|
||||
}
|
||||
}
|
||||
|
||||
len = min(so->so_snd.sb_cc, 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 + so->so_snd.sb_cc))
|
||||
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 >= so->so_snd.sb_cc)
|
||||
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) so->so_rcv.sb_datalen)
|
||||
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 (so->so_snd.sb_cc && 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.
|
||||
*/
|
||||
return (0);
|
||||
|
||||
send:
|
||||
/*
|
||||
* 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) {
|
||||
uint16_t mss;
|
||||
|
||||
opt[0] = TCPOPT_MAXSEG;
|
||||
opt[1] = 4;
|
||||
mss = htons((uint16_t) tcp_mss(tp, 0));
|
||||
memcpy((caddr_t)(opt + 2), (caddr_t)&mss, sizeof(mss));
|
||||
optlen = 4;
|
||||
}
|
||||
}
|
||||
|
||||
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) {
|
||||
m = m_get(so->slirp);
|
||||
if (m == NULL) {
|
||||
error = 1;
|
||||
goto out;
|
||||
}
|
||||
m->m_data += IF_MAXLINKHDR;
|
||||
m->m_len = hdrlen;
|
||||
|
||||
sbcopy(&so->so_snd, off, (int) len, mtod(m, caddr_t) + hdrlen);
|
||||
m->m_len += len;
|
||||
|
||||
/*
|
||||
* 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 == so->so_snd.sb_cc)
|
||||
flags |= TH_PUSH;
|
||||
} else {
|
||||
m = m_get(so->slirp);
|
||||
if (m == NULL) {
|
||||
error = 1;
|
||||
goto out;
|
||||
}
|
||||
m->m_data += IF_MAXLINKHDR;
|
||||
m->m_len = hdrlen;
|
||||
}
|
||||
|
||||
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 = htonl(tp->snd_nxt);
|
||||
else
|
||||
ti->ti_seq = htonl(tp->snd_max);
|
||||
ti->ti_ack = htonl(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)(so->so_rcv.sb_datalen / 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 = htons((uint16_t) (win>>tp->rcv_scale));
|
||||
|
||||
if (SEQ_GT(tp->snd_up, tp->snd_una)) {
|
||||
ti->ti_urp = htons((uint16_t)(tp->snd_up - ntohl(ti->ti_seq)));
|
||||
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 = htons((uint16_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;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* 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->m_len = hdrlen + len; /* XXX Needed? m_len should be correct */
|
||||
|
||||
{
|
||||
|
||||
((struct ip *)ti)->ip_len = m->m_len;
|
||||
|
||||
((struct ip *)ti)->ip_ttl = IPDEFTTL;
|
||||
((struct ip *)ti)->ip_tos = so->so_iptos;
|
||||
|
||||
error = ip_output(so, m);
|
||||
}
|
||||
if (error) {
|
||||
out:
|
||||
return (error);
|
||||
}
|
||||
|
||||
/*
|
||||
* 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;
|
||||
|
||||
/*
|
||||
* 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++;
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue