diff options
Diffstat (limited to 'slirp/src/tcp_output.c')
| m--------- | slirp | 0 | ||||
| -rw-r--r-- | slirp/src/tcp_output.c | 522 |
2 files changed, 0 insertions, 522 deletions
diff --git a/slirp b/slirp new file mode 160000 +Subproject 59a1b1f165458c2acb7ff0525b543945f741622 diff --git a/slirp/src/tcp_output.c b/slirp/src/tcp_output.c deleted file mode 100644 index 6bbaf6ca6f..0000000000 --- a/slirp/src/tcp_output.c +++ /dev/null @@ -1,522 +0,0 @@ -/* SPDX-License-Identifier: BSD-3-Clause */ -/* - * 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. - */ - -#include "slirp.h" - -static const uint8_t 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, -}; - - -#undef MAX_TCPOPTLEN -#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, tcpiph_save; - struct ip *ip; - struct ip6 *ip6; - uint8_t opt[MAX_TCPOPTLEN]; - unsigned optlen, hdrlen; - int idle, sendalot; - - DEBUG_CALL("tcp_output"); - DEBUG_ARG("tp = %p", 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(" --- tcp_output flags = 0x%x", 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((char *)(opt + 2), (char *)&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, char *) + 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((char *)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((char *)(ti + 1), (char *)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 */ - tcpiph_save = *mtod(m, struct tcpiphdr *); - - switch (so->so_ffamily) { - case AF_INET: - m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr) - - sizeof(struct ip); - m->m_len -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr) - - sizeof(struct ip); - ip = mtod(m, struct ip *); - - ip->ip_len = m->m_len; - ip->ip_dst = tcpiph_save.ti_dst; - ip->ip_src = tcpiph_save.ti_src; - ip->ip_p = tcpiph_save.ti_pr; - - ip->ip_ttl = IPDEFTTL; - ip->ip_tos = so->so_iptos; - error = ip_output(so, m); - break; - - case AF_INET6: - m->m_data += sizeof(struct tcpiphdr) - sizeof(struct tcphdr) - - sizeof(struct ip6); - m->m_len -= sizeof(struct tcpiphdr) - sizeof(struct tcphdr) - - sizeof(struct ip6); - ip6 = mtod(m, struct ip6 *); - - ip6->ip_pl = tcpiph_save.ti_len; - ip6->ip_dst = tcpiph_save.ti_dst6; - ip6->ip_src = tcpiph_save.ti_src6; - ip6->ip_nh = tcpiph_save.ti_nh6; - - error = ip6_output(so, m, 0); - break; - - default: - g_assert_not_reached(); - } - - 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++; -} |