diff options
Diffstat (limited to 'sys/netinet/tcp_output.c')
| -rw-r--r-- | sys/netinet/tcp_output.c | 943 |
1 files changed, 943 insertions, 0 deletions
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c new file mode 100644 index 0000000..286b420 --- /dev/null +++ b/sys/netinet/tcp_output.c @@ -0,0 +1,943 @@ +/* + * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 + * 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 8.4 (Berkeley) 5/24/95 + * $FreeBSD$ + */ + +#include "opt_inet6.h" +#include "opt_ipsec.h" +#include "opt_tcpdebug.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/domain.h> +#include <sys/kernel.h> +#include <sys/lock.h> +#include <sys/mbuf.h> +#include <sys/mutex.h> +#include <sys/protosw.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/sysctl.h> + +#include <net/route.h> + +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/in_pcb.h> +#include <netinet/ip_var.h> +#ifdef INET6 +#include <netinet6/in6_pcb.h> +#include <netinet/ip6.h> +#include <netinet6/ip6_var.h> +#endif +#include <netinet/tcp.h> +#define TCPOUTFLAGS +#include <netinet/tcp_fsm.h> +#include <netinet/tcp_seq.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet/tcpip.h> +#ifdef TCPDEBUG +#include <netinet/tcp_debug.h> +#endif + +#ifdef IPSEC +#include <netinet6/ipsec.h> +#endif /*IPSEC*/ + +#include <machine/in_cksum.h> + +#ifdef notyet +extern struct mbuf *m_copypack(); +#endif + +static int path_mtu_discovery = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_RW, + &path_mtu_discovery, 1, "Enable Path MTU Discovery"); + +int ss_fltsz = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, slowstart_flightsize, CTLFLAG_RW, + &ss_fltsz, 1, "Slow start flight size"); + +int ss_fltsz_local = TCP_MAXWIN; /* something large */ +SYSCTL_INT(_net_inet_tcp, OID_AUTO, local_slowstart_flightsize, CTLFLAG_RW, + &ss_fltsz_local, 1, "Slow start flight size for local networks"); + +int tcp_do_newreno = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, newreno, CTLFLAG_RW, &tcp_do_newreno, + 0, "Enable NewReno Algorithms"); +/* + * Tcp output routine: figure out what should be sent and send it. + */ +int +tcp_output(tp) + register struct tcpcb *tp; +{ + register struct socket *so = tp->t_inpcb->inp_socket; + register long len, win; + int off, flags, error; + register struct mbuf *m; + struct ip *ip = NULL; + register struct ipovly *ipov = NULL; +#ifdef INET6 + struct ip6_hdr *ip6 = NULL; +#endif /* INET6 */ + register struct tcphdr *th; + u_char opt[TCP_MAXOLEN]; + unsigned ipoptlen, optlen, hdrlen; + int idle, sendalot; + int maxburst = TCP_MAXBURST; + struct rmxp_tao *taop; + struct rmxp_tao tao_noncached; +#ifdef INET6 + int isipv6; +#endif + +#ifdef INET6 + isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0; +#endif + + /* + * 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 && (ticks - tp->t_rcvtime) >= 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. + * + * Set the slow-start flight size depending on whether + * this is a local network or not. + */ + if ( +#ifdef INET6 + (isipv6 && in6_localaddr(&tp->t_inpcb->in6p_faddr)) || + (!isipv6 && +#endif + in_localaddr(tp->t_inpcb->inp_faddr) +#ifdef INET6 + ) +#endif + ) + tp->snd_cwnd = tp->t_maxseg * ss_fltsz_local; + else + tp->snd_cwnd = tp->t_maxseg * ss_fltsz; + } +again: + sendalot = 0; + off = tp->snd_nxt - tp->snd_una; + win = min(tp->snd_wnd, tp->snd_cwnd); + + flags = tcp_outflags[tp->t_state]; + /* + * Get standard flags, and add SYN or FIN if requested by 'hidden' + * state flags. + */ + if (tp->t_flags & TF_NEEDFIN) + flags |= TH_FIN; + if (tp->t_flags & TF_NEEDSYN) + flags |= TH_SYN; + + /* + * 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 unsent 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 { + callout_stop(tp->tt_persist); + tp->t_rxtshift = 0; + } + } + + len = (long)ulmin(so->so_snd.sb_cc, win) - off; + + if ((taop = tcp_gettaocache(tp->t_inpcb)) == NULL) { + taop = &tao_noncached; + bzero(taop, sizeof(*taop)); + } + + /* + * Lop off SYN bit if it has already been sent. However, if this + * is SYN-SENT state and if segment contains data and if we don't + * know that foreign host supports TAO, suppress sending segment. + */ + if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una)) { + flags &= ~TH_SYN; + off--, len++; + if (len > 0 && tp->t_state == TCPS_SYN_SENT && + taop->tao_ccsent == 0) + return 0; + } + + /* + * Be careful not to send data and/or FIN on SYN segments + * in cases when no CC option will be sent. + * This measure is needed to prevent interoperability problems + * with not fully conformant TCP implementations. + */ + if ((flags & TH_SYN) && + ((tp->t_flags & TF_NOOPT) || !(tp->t_flags & TF_REQ_CC) || + ((flags & TH_ACK) && !(tp->t_flags & TF_RCVD_CC)))) { + len = 0; + flags &= ~TH_FIN; + } + + 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, pull snd_nxt back + * to (closed) window, and set the persist timer + * if it isn't already going. If the window didn't + * close completely, just wait for an ACK. + */ + len = 0; + if (win == 0) { + callout_stop(tp->tt_rexmt); + tp->t_rxtshift = 0; + tp->snd_nxt = tp->snd_una; + if (!callout_active(tp->tt_persist)) + tcp_setpersist(tp); + } + } + 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 (!(tp->t_flags & TF_MORETOCOME) && + (idle || tp->t_flags & TF_NODELAY) && + (tp->t_flags & TF_NOPUSH) == 0 && + 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_hiwat) + goto send; + } + + /* + * Send if we owe peer an ACK. + */ + if (tp->t_flags & TF_ACKNOW) + goto send; + if ((flags & TH_RST) || + ((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0)) + 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 + * + * callout_active(tp->tt_persist) + * is true when we are in persist state. + * tp->t_force + * is set when we are called to send a persist packet. + * callout_active(tp->tt_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 && !callout_active(tp->tt_rexmt) && + !callout_active(tp->tt_persist)) { + 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; +#ifdef INET6 + if (isipv6) + hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr); + else +#endif + hdrlen = sizeof (struct tcpiphdr); + if (flags & TH_SYN) { + tp->snd_nxt = tp->iss; + if ((tp->t_flags & TF_NOOPT) == 0) { + u_short mss; + + opt[0] = TCPOPT_MAXSEG; + opt[1] = TCPOLEN_MAXSEG; + mss = htons((u_short) tcp_mssopt(tp)); + (void)memcpy(opt + 2, &mss, sizeof(mss)); + optlen = TCPOLEN_MAXSEG; + + if ((tp->t_flags & TF_REQ_SCALE) && + ((flags & TH_ACK) == 0 || + (tp->t_flags & TF_RCVD_SCALE))) { + *((u_int32_t *)(opt + optlen)) = htonl( + TCPOPT_NOP << 24 | + TCPOPT_WINDOW << 16 | + TCPOLEN_WINDOW << 8 | + tp->request_r_scale); + optlen += 4; + } + } + } + + /* + * 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 ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && + (flags & TH_RST) == 0 && + ((flags & TH_ACK) == 0 || + (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++ = htonl(TCPOPT_TSTAMP_HDR); + *lp++ = htonl(ticks); + *lp = htonl(tp->ts_recent); + optlen += TCPOLEN_TSTAMP_APPA; + } + + /* + * Send `CC-family' options if our side wants to use them (TF_REQ_CC), + * options are allowed (!TF_NOOPT) and it's not a RST. + */ + if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && + (flags & TH_RST) == 0) { + switch (flags & (TH_SYN|TH_ACK)) { + /* + * This is a normal ACK, send CC if we received CC before + * from our peer. + */ + case TH_ACK: + if (!(tp->t_flags & TF_RCVD_CC)) + break; + /*FALLTHROUGH*/ + + /* + * We can only get here in T/TCP's SYN_SENT* state, when + * we're a sending a non-SYN segment without waiting for + * the ACK of our SYN. A check above assures that we only + * do this if our peer understands T/TCP. + */ + case 0: + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_CC; + opt[optlen++] = TCPOLEN_CC; + *(u_int32_t *)&opt[optlen] = htonl(tp->cc_send); + + optlen += 4; + break; + + /* + * This is our initial SYN, check whether we have to use + * CC or CC.new. + */ + case TH_SYN: + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = tp->t_flags & TF_SENDCCNEW ? + TCPOPT_CCNEW : TCPOPT_CC; + opt[optlen++] = TCPOLEN_CC; + *(u_int32_t *)&opt[optlen] = htonl(tp->cc_send); + optlen += 4; + break; + + /* + * This is a SYN,ACK; send CC and CC.echo if we received + * CC from our peer. + */ + case (TH_SYN|TH_ACK): + if (tp->t_flags & TF_RCVD_CC) { + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_CC; + opt[optlen++] = TCPOLEN_CC; + *(u_int32_t *)&opt[optlen] = + htonl(tp->cc_send); + optlen += 4; + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_NOP; + opt[optlen++] = TCPOPT_CCECHO; + opt[optlen++] = TCPOLEN_CC; + *(u_int32_t *)&opt[optlen] = + htonl(tp->cc_recv); + optlen += 4; + } + break; + } + } + + hdrlen += optlen; + +#ifdef INET6 + if (isipv6) + ipoptlen = ip6_optlen(tp->t_inpcb); + else +#endif + { + if (tp->t_inpcb->inp_options) { + ipoptlen = tp->t_inpcb->inp_options->m_len - + offsetof(struct ipoption, ipopt_list); + } else { + ipoptlen = 0; + } + } +#ifdef IPSEC + ipoptlen += ipsec_hdrsiz_tcp(tp); +#endif + + /* + * Adjust data length if insertion of options will + * bump the packet length beyond the t_maxopd length. + * Clear the FIN bit because we cut off the tail of + * the segment. + */ + if (len + optlen + ipoptlen > tp->t_maxopd) { + /* + * If there is still more to send, don't close the connection. + */ + flags &= ~TH_FIN; + len = tp->t_maxopd - optlen - ipoptlen; + sendalot = 1; + } + +/*#ifdef DIAGNOSTIC*/ +#ifdef INET6 + if (max_linkhdr + hdrlen > MCLBYTES) + panic("tcphdr too big"); +#else + if (max_linkhdr + hdrlen > MHLEN) + panic("tcphdr too big"); +#endif +/*#endif*/ + + /* + * 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; + } +#ifdef notyet + if ((m = m_copypack(so->so_snd.sb_mb, off, + (int)len, max_linkhdr + hdrlen)) == 0) { + error = ENOBUFS; + goto out; + } + /* + * m_copypack left space for our hdr; use it. + */ + m->m_len += hdrlen; + m->m_data -= hdrlen; +#else + MGETHDR(m, M_DONTWAIT, MT_HEADER); + if (m == NULL) { + error = ENOBUFS; + goto out; + } +#ifdef INET6 + if (MHLEN < hdrlen + max_linkhdr) { + MCLGET(m, M_DONTWAIT); + if ((m->m_flags & M_EXT) == 0) { + m_freem(m); + error = ENOBUFS; + goto out; + } + } +#endif + m->m_data += max_linkhdr; + m->m_len = hdrlen; + if (len <= MHLEN - hdrlen - max_linkhdr) { + m_copydata(so->so_snd.sb_mb, off, (int) len, + mtod(m, caddr_t) + hdrlen); + m->m_len += len; + } else { + m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len); + if (m->m_next == 0) { + (void) m_free(m); + error = ENOBUFS; + goto out; + } + } +#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 == so->so_snd.sb_cc) + flags |= TH_PUSH; + } else { + 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++; + + MGETHDR(m, M_DONTWAIT, MT_HEADER); + if (m == NULL) { + error = ENOBUFS; + goto out; + } +#ifdef INET6 + if (isipv6 && (MHLEN < hdrlen + max_linkhdr) && + MHLEN >= hdrlen) { + MH_ALIGN(m, hdrlen); + } else +#endif + m->m_data += max_linkhdr; + m->m_len = hdrlen; + } + m->m_pkthdr.rcvif = (struct ifnet *)0; + if (tp->t_template == 0) + panic("tcp_output"); +#ifdef INET6 + if (isipv6) { + ip6 = mtod(m, struct ip6_hdr *); + th = (struct tcphdr *)(ip6 + 1); + bcopy((caddr_t)tp->t_template->tt_ipgen, (caddr_t)ip6, + sizeof(struct ip6_hdr)); + bcopy((caddr_t)&tp->t_template->tt_t, (caddr_t)th, + sizeof(struct tcphdr)); + } else +#endif /* INET6 */ + { + ip = mtod(m, struct ip *); + ipov = (struct ipovly *)ip; + th = (struct tcphdr *)(ip + 1); + /* this picks up the pseudo header (w/o the length) */ + bcopy((caddr_t)tp->t_template->tt_ipgen, (caddr_t)ip, + sizeof(struct ip)); + bcopy((caddr_t)&tp->t_template->tt_t, (caddr_t)th, + sizeof(struct tcphdr)); + } + + /* + * 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)) + || callout_active(tp->tt_persist)) + th->th_seq = htonl(tp->snd_nxt); + else + th->th_seq = htonl(tp->snd_max); + th->th_ack = htonl(tp->rcv_nxt); + if (optlen) { + bcopy(opt, th + 1, optlen); + th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; + } + th->th_flags = flags; + /* + * Calculate receive window. Don't shrink window, + * but avoid silly window syndrome. + */ + if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)tp->t_maxseg) + win = 0; + if (win < (long)(tp->rcv_adv - tp->rcv_nxt)) + win = (long)(tp->rcv_adv - tp->rcv_nxt); + if (win > (long)TCP_MAXWIN << tp->rcv_scale) + win = (long)TCP_MAXWIN << tp->rcv_scale; + th->th_win = htons((u_short) (win>>tp->rcv_scale)); + if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { + th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt)); + th->th_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. + */ + m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */ +#ifdef INET6 + if (isipv6) + /* + * ip6_plen is not need to be filled now, and will be filled + * in ip6_output. + */ + th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr), + sizeof(struct tcphdr) + optlen + len); + else +#endif /* INET6 */ + { + m->m_pkthdr.csum_flags = CSUM_TCP; + m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); + if (len + optlen) + th->th_sum = in_addword(th->th_sum, + htons((u_short)(optlen + len))); + + /* IP version must be set here for ipv4/ipv6 checking later */ + KASSERT(ip->ip_v == IPVERSION, + ("%s: IP version incorrect: %d", __FUNCTION__, ip->ip_v)); + } + + /* + * In transmit state, time the transmission and arrange for + * the retransmit. In persist state, just set snd_max. + */ + if (tp->t_force == 0 || !callout_active(tp->tt_persist)) { + 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_rtttime == 0) { + tp->t_rtttime = ticks; + 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 (!callout_active(tp->tt_rexmt) && + tp->snd_nxt != tp->snd_una) { + if (callout_active(tp->tt_persist)) { + callout_stop(tp->tt_persist); + tp->t_rxtshift = 0; + } + callout_reset(tp->tt_rexmt, tp->t_rxtcur, + tcp_timer_rexmt, tp); + } + } else + if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) + tp->snd_max = tp->snd_nxt + len; + +#ifdef TCPDEBUG + /* + * Trace. + */ + if (so->so_options & SO_DEBUG) + tcp_trace(TA_OUTPUT, tp->t_state, tp, mtod(m, void *), th, 0); +#endif + + /* + * 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_pkthdr.len should have been set before cksum calcuration, + * because in6_cksum() need it. + */ +#ifdef INET6 + if (isipv6) { + /* + * we separately set hoplimit for every segment, since the + * user might want to change the value via setsockopt. + * Also, desired default hop limit might be changed via + * Neighbor Discovery. + */ + ip6->ip6_hlim = in6_selecthlim(tp->t_inpcb, + tp->t_inpcb->in6p_route.ro_rt ? + tp->t_inpcb->in6p_route.ro_rt->rt_ifp + : NULL); + + /* TODO: IPv6 IP6TOS_ECT bit on */ +#ifdef IPSEC + ipsec_setsocket(m, so); +#endif /*IPSEC*/ + error = ip6_output(m, + tp->t_inpcb->in6p_outputopts, + &tp->t_inpcb->in6p_route, + (so->so_options & SO_DONTROUTE), NULL, NULL); + } else +#endif /* INET6 */ + { + struct rtentry *rt; + ip->ip_len = m->m_pkthdr.len; +#ifdef INET6 + if (INP_CHECK_SOCKAF(so, AF_INET6)) + ip->ip_ttl = in6_selecthlim(tp->t_inpcb, + tp->t_inpcb->in6p_route.ro_rt ? + tp->t_inpcb->in6p_route.ro_rt->rt_ifp + : NULL); + else +#endif /* INET6 */ + ip->ip_ttl = tp->t_inpcb->inp_ip_ttl; /* XXX */ + ip->ip_tos = tp->t_inpcb->inp_ip_tos; /* XXX */ + /* + * See if we should do MTU discovery. We do it only if the following + * are true: + * 1) we have a valid route to the destination + * 2) the MTU is not locked (if it is, then discovery has been + * disabled) + */ + if (path_mtu_discovery + && (rt = tp->t_inpcb->inp_route.ro_rt) + && rt->rt_flags & RTF_UP + && !(rt->rt_rmx.rmx_locks & RTV_MTU)) { + ip->ip_off |= IP_DF; + } +#ifdef IPSEC + ipsec_setsocket(m, so); +#endif /*IPSEC*/ + error = ip_output(m, tp->t_inpcb->inp_options, &tp->t_inpcb->inp_route, + (so->so_options & SO_DONTROUTE), 0); + } + if (error) { + + /* + * We know that the packet was lost, so back out the + * sequence number advance, if any. + */ + if (tp->t_force == 0 || !callout_active(tp->tt_persist)) { + /* + * No need to check for TH_FIN here because + * the TF_SENTFIN flag handles that case. + */ + if ((flags & TH_SYN) == 0) + tp->snd_nxt -= len; + } + +out: + if (error == ENOBUFS) { + if (!callout_active(tp->tt_rexmt) && + !callout_active(tp->tt_persist)) + callout_reset(tp->tt_rexmt, tp->t_rxtcur, + tcp_timer_rexmt, tp); + tcp_quench(tp->t_inpcb, 0); + return (0); + } + if (error == EMSGSIZE) { + /* + * ip_output() will have already fixed the route + * for us. tcp_mtudisc() will, as its last action, + * initiate retransmission, so it is important to + * not do so here. + */ + tcp_mtudisc(tp->t_inpcb, 0); + return 0; + } + if ((error == EHOSTUNREACH || error == ENETDOWN) + && TCPS_HAVERCVDSYN(tp->t_state)) { + tp->t_softerror = error; + return (0); + } + 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; + if (tcp_delack_enabled) + callout_stop(tp->tt_delack); + if (sendalot && (!tcp_do_newreno || --maxburst)) + goto again; + return (0); +} + +void +tcp_setpersist(tp) + register struct tcpcb *tp; +{ + int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; + int tt; + + if (callout_active(tp->tt_rexmt)) + panic("tcp_setpersist: retransmit pending"); + /* + * Start/restart persistance timer. + */ + TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift], + TCPTV_PERSMIN, TCPTV_PERSMAX); + callout_reset(tp->tt_persist, tt, tcp_timer_persist, tp); + if (tp->t_rxtshift < TCP_MAXRXTSHIFT) + tp->t_rxtshift++; +} |
