diff options
Diffstat (limited to 'c/src/exec/libnetworking/netinet/tcp_input.c')
| -rw-r--r-- | c/src/exec/libnetworking/netinet/tcp_input.c | 2150 |
1 files changed, 0 insertions, 2150 deletions
diff --git a/c/src/exec/libnetworking/netinet/tcp_input.c b/c/src/exec/libnetworking/netinet/tcp_input.c deleted file mode 100644 index 183b976f89..0000000000 --- a/c/src/exec/libnetworking/netinet/tcp_input.c +++ /dev/null @@ -1,2150 +0,0 @@ -/* - * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 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 acknowledgment: - * 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_input.c 8.12 (Berkeley) 5/24/95 - * $Id$ - */ - -#include "opt_tcpdebug.h" - -#ifndef TUBA_INCLUDE -#include <sys/param.h> -#include <sys/queue.h> -#include <sys/systm.h> -#include <sys/kernel.h> -#include <sys/sysctl.h> -#include <sys/malloc.h> -#include <sys/mbuf.h> -#include <sys/protosw.h> -#include <sys/socket.h> -#include <sys/socketvar.h> -#include <sys/errno.h> -#include <sys/syslog.h> - -#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ - -#include <net/if.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> -#include <netinet/tcp.h> -#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> -static struct tcpiphdr tcp_saveti; -#endif - -static int tcprexmtthresh = 3; -tcp_seq tcp_iss; -tcp_cc tcp_ccgen; - -struct tcpstat tcpstat; -SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, - CTLFLAG_RD, &tcpstat , tcpstat, ""); - -static int log_in_vain = 0; -SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, - &log_in_vain, 0, ""); - -u_long tcp_now; -struct inpcbhead tcb; -struct inpcbinfo tcbinfo; - -static void tcp_dooptions __P((struct tcpcb *, - u_char *, int, struct tcpiphdr *, struct tcpopt *)); -static void tcp_pulloutofband __P((struct socket *, - struct tcpiphdr *, struct mbuf *)); -static int tcp_reass __P((struct tcpcb *, struct tcpiphdr *, struct mbuf *)); -static void tcp_xmit_timer __P((struct tcpcb *, int)); - -#endif /* TUBA_INCLUDE */ - -/* - * Insert segment ti into reassembly queue of tcp with - * control block tp. Return TH_FIN if reassembly now includes - * a segment with FIN. The macro form does the common case inline - * (segment is the next to be received on an established connection, - * and the queue is empty), avoiding linkage into and removal - * from the queue and repetition of various conversions. - * Set DELACK for segments received in order, but ack immediately - * when segments are out of order (so fast retransmit can work). - */ -#ifdef TCP_ACK_HACK -#define TCP_REASS(tp, ti, m, so, flags) { \ - if ((ti)->ti_seq == (tp)->rcv_nxt && \ - (tp)->seg_next == (struct tcpiphdr *)(tp) && \ - (tp)->t_state == TCPS_ESTABLISHED) { \ - if (ti->ti_flags & TH_PUSH) \ - tp->t_flags |= TF_ACKNOW; \ - else \ - tp->t_flags |= TF_DELACK; \ - (tp)->rcv_nxt += (ti)->ti_len; \ - flags = (ti)->ti_flags & TH_FIN; \ - tcpstat.tcps_rcvpack++;\ - tcpstat.tcps_rcvbyte += (ti)->ti_len;\ - sbappend(&(so)->so_rcv, (m)); \ - sorwakeup(so); \ - } else { \ - (flags) = tcp_reass((tp), (ti), (m)); \ - tp->t_flags |= TF_ACKNOW; \ - } \ -} -#else -#define TCP_REASS(tp, ti, m, so, flags) { \ - if ((ti)->ti_seq == (tp)->rcv_nxt && \ - (tp)->seg_next == (struct tcpiphdr *)(tp) && \ - (tp)->t_state == TCPS_ESTABLISHED) { \ - tp->t_flags |= TF_DELACK; \ - (tp)->rcv_nxt += (ti)->ti_len; \ - flags = (ti)->ti_flags & TH_FIN; \ - tcpstat.tcps_rcvpack++;\ - tcpstat.tcps_rcvbyte += (ti)->ti_len;\ - sbappend(&(so)->so_rcv, (m)); \ - sorwakeup(so); \ - } else { \ - (flags) = tcp_reass((tp), (ti), (m)); \ - tp->t_flags |= TF_ACKNOW; \ - } \ -} -#endif -#ifndef TUBA_INCLUDE - -static int -tcp_reass(tp, ti, m) - register struct tcpcb *tp; - register struct tcpiphdr *ti; - struct mbuf *m; -{ - register struct tcpiphdr *q; - struct socket *so = tp->t_inpcb->inp_socket; - int flags; - - /* - * Call with ti==0 after become established to - * force pre-ESTABLISHED data up to user socket. - */ - if (ti == 0) - goto present; - - /* - * Find a segment which begins after this one does. - */ - for (q = tp->seg_next; q != (struct tcpiphdr *)tp; - q = (struct tcpiphdr *)q->ti_next) - if (SEQ_GT(q->ti_seq, ti->ti_seq)) - break; - - /* - * If there is a preceding segment, it may provide some of - * our data already. If so, drop the data from the incoming - * segment. If it provides all of our data, drop us. - */ - if ((struct tcpiphdr *)q->ti_prev != (struct tcpiphdr *)tp) { - register int i; - q = (struct tcpiphdr *)q->ti_prev; - /* conversion to int (in i) handles seq wraparound */ - i = q->ti_seq + q->ti_len - ti->ti_seq; - if (i > 0) { - if (i >= ti->ti_len) { - tcpstat.tcps_rcvduppack++; - tcpstat.tcps_rcvdupbyte += ti->ti_len; - m_freem(m); - /* - * Try to present any queued data - * at the left window edge to the user. - * This is needed after the 3-WHS - * completes. - */ - goto present; /* ??? */ - } - m_adj(m, i); - ti->ti_len -= i; - ti->ti_seq += i; - } - q = (struct tcpiphdr *)(q->ti_next); - } - tcpstat.tcps_rcvoopack++; - tcpstat.tcps_rcvoobyte += ti->ti_len; - REASS_MBUF(ti) = m; /* XXX */ - - /* - * While we overlap succeeding segments trim them or, - * if they are completely covered, dequeue them. - */ - while (q != (struct tcpiphdr *)tp) { - register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq; - if (i <= 0) - break; - if (i < q->ti_len) { - q->ti_seq += i; - q->ti_len -= i; - m_adj(REASS_MBUF(q), i); - break; - } - q = (struct tcpiphdr *)q->ti_next; - m = REASS_MBUF((struct tcpiphdr *)q->ti_prev); - remque(q->ti_prev); - m_freem(m); - } - - /* - * Stick new segment in its place. - */ - insque(ti, q->ti_prev); - -present: - /* - * Present data to user, advancing rcv_nxt through - * completed sequence space. - */ - if (!TCPS_HAVEESTABLISHED(tp->t_state)) - return (0); - ti = tp->seg_next; - if (ti == (struct tcpiphdr *)tp || ti->ti_seq != tp->rcv_nxt) - return (0); - do { - tp->rcv_nxt += ti->ti_len; - flags = ti->ti_flags & TH_FIN; - remque(ti); - m = REASS_MBUF(ti); - ti = (struct tcpiphdr *)ti->ti_next; - if (so->so_state & SS_CANTRCVMORE) - m_freem(m); - else - sbappend(&so->so_rcv, m); - } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); - sorwakeup(so); - return (flags); -} - -/* - * TCP input routine, follows pages 65-76 of the - * protocol specification dated September, 1981 very closely. - */ -void -tcp_input(m, iphlen) - register struct mbuf *m; - int iphlen; -{ - register struct tcpiphdr *ti; - register struct inpcb *inp; - u_char *optp = NULL; - int optlen = 0; - int len, tlen, off; - register struct tcpcb *tp = 0; - register int tiflags; - struct socket *so = 0; - int todrop, acked, ourfinisacked, needoutput = 0; - struct in_addr laddr; - int dropsocket = 0; - int iss = 0; - u_long tiwin; - struct tcpopt to; /* options in this segment */ - struct rmxp_tao *taop; /* pointer to our TAO cache entry */ - struct rmxp_tao tao_noncached; /* in case there's no cached entry */ -#ifdef TCPDEBUG - short ostate = 0; -#endif - - bzero((char *)&to, sizeof(to)); - - tcpstat.tcps_rcvtotal++; - /* - * Get IP and TCP header together in first mbuf. - * Note: IP leaves IP header in first mbuf. - */ - ti = mtod(m, struct tcpiphdr *); - if (iphlen > sizeof (struct ip)) - ip_stripoptions(m, (struct mbuf *)0); - if (m->m_len < sizeof (struct tcpiphdr)) { - if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { - tcpstat.tcps_rcvshort++; - return; - } - ti = mtod(m, struct tcpiphdr *); - } - - /* - * Checksum extended TCP header and data. - */ - tlen = ((struct ip *)ti)->ip_len; - len = sizeof (struct ip) + tlen; - ti->ti_next = ti->ti_prev = 0; - ti->ti_x1 = 0; - ti->ti_len = (u_short)tlen; - HTONS(ti->ti_len); - ti->ti_sum = in_cksum(m, len); - if (ti->ti_sum) { - tcpstat.tcps_rcvbadsum++; - goto drop; - } -#endif /* TUBA_INCLUDE */ - - /* - * Check that TCP offset makes sense, - * pull out TCP options and adjust length. XXX - */ - off = ti->ti_off << 2; - if (off < sizeof (struct tcphdr) || off > tlen) { - tcpstat.tcps_rcvbadoff++; - goto drop; - } - tlen -= off; - ti->ti_len = tlen; - if (off > sizeof (struct tcphdr)) { - if (m->m_len < sizeof(struct ip) + off) { - if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { - tcpstat.tcps_rcvshort++; - return; - } - ti = mtod(m, struct tcpiphdr *); - } - optlen = off - sizeof (struct tcphdr); - optp = mtod(m, u_char *) + sizeof (struct tcpiphdr); - } - tiflags = ti->ti_flags; - - /* - * Convert TCP protocol specific fields to host format. - */ - NTOHL(ti->ti_seq); - NTOHL(ti->ti_ack); - NTOHS(ti->ti_win); - NTOHS(ti->ti_urp); - - /* - * Drop TCP, IP headers and TCP options. - */ - m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); - m->m_len -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); - - /* - * Locate pcb for segment. - */ -findpcb: - inp = in_pcblookuphash(&tcbinfo, ti->ti_src, ti->ti_sport, - ti->ti_dst, ti->ti_dport, 1); - - /* - * If the state is CLOSED (i.e., TCB does not exist) then - * all data in the incoming segment is discarded. - * If the TCB exists but is in CLOSED state, it is embryonic, - * but should either do a listen or a connect soon. - */ - if (inp == NULL) { - if (log_in_vain && tiflags & TH_SYN) { - char buf[4*sizeof "123"]; - - strcpy(buf, inet_ntoa(ti->ti_dst)); - log(LOG_INFO, "Connection attempt to TCP %s:%d" - " from %s:%d\n", - buf, ntohs(ti->ti_dport), - inet_ntoa(ti->ti_src), ntohs(ti->ti_sport)); - } - goto dropwithreset; - } - tp = intotcpcb(inp); - if (tp == 0) - goto dropwithreset; - if (tp->t_state == TCPS_CLOSED) - goto drop; - - /* Unscale the window into a 32-bit value. */ - if ((tiflags & TH_SYN) == 0) - tiwin = ti->ti_win << tp->snd_scale; - else - tiwin = ti->ti_win; - - so = inp->inp_socket; - if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { -#ifdef TCPDEBUG - if (so->so_options & SO_DEBUG) { - ostate = tp->t_state; - tcp_saveti = *ti; - } -#endif - if (so->so_options & SO_ACCEPTCONN) { - register struct tcpcb *tp0 = tp; - struct socket *so2; - if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { - /* - * Note: dropwithreset makes sure we don't - * send a RST in response to a RST. - */ - if (tiflags & TH_ACK) { - tcpstat.tcps_badsyn++; - goto dropwithreset; - } - goto drop; - } - so2 = sonewconn(so, 0); - if (so2 == 0) { - tcpstat.tcps_listendrop++; - so2 = sodropablereq(so); - if (so2) { - tcp_drop(sototcpcb(so2), ETIMEDOUT); - so2 = sonewconn(so, 0); - } - if (!so2) - goto drop; - } - so = so2; - /* - * This is ugly, but .... - * - * Mark socket as temporary until we're - * committed to keeping it. The code at - * ``drop'' and ``dropwithreset'' check the - * flag dropsocket to see if the temporary - * socket created here should be discarded. - * We mark the socket as discardable until - * we're committed to it below in TCPS_LISTEN. - */ - dropsocket++; - inp = (struct inpcb *)so->so_pcb; - inp->inp_laddr = ti->ti_dst; - inp->inp_lport = ti->ti_dport; - in_pcbrehash(inp); -#if BSD>=43 - inp->inp_options = ip_srcroute(); -#endif - tp = intotcpcb(inp); - tp->t_state = TCPS_LISTEN; - tp->t_flags |= tp0->t_flags & (TF_NOPUSH|TF_NOOPT); - - /* Compute proper scaling value from buffer space */ - while (tp->request_r_scale < TCP_MAX_WINSHIFT && - TCP_MAXWIN << tp->request_r_scale < so->so_rcv.sb_hiwat) - tp->request_r_scale++; - } - } - - /* - * Segment received on connection. - * Reset idle time and keep-alive timer. - */ - tp->t_idle = 0; - if (TCPS_HAVEESTABLISHED(tp->t_state)) - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - - /* - * Process options if not in LISTEN state, - * else do it below (after getting remote address). - */ - if (tp->t_state != TCPS_LISTEN) - tcp_dooptions(tp, optp, optlen, ti, &to); - - /* - * Header prediction: check for the two common cases - * of a uni-directional data xfer. If the packet has - * no control flags, is in-sequence, the window didn't - * change and we're not retransmitting, it's a - * candidate. If the length is zero and the ack moved - * forward, we're the sender side of the xfer. Just - * free the data acked & wake any higher level process - * that was blocked waiting for space. If the length - * is non-zero and the ack didn't move, we're the - * receiver side. If we're getting packets in-order - * (the reassembly queue is empty), add the data to - * the socket buffer and note that we need a delayed ack. - * Make sure that the hidden state-flags are also off. - * Since we check for TCPS_ESTABLISHED above, it can only - * be TH_NEEDSYN. - */ - if (tp->t_state == TCPS_ESTABLISHED && - (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && - ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && - ((to.to_flag & TOF_TS) == 0 || - TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && - /* - * Using the CC option is compulsory if once started: - * the segment is OK if no T/TCP was negotiated or - * if the segment has a CC option equal to CCrecv - */ - ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) != (TF_REQ_CC|TF_RCVD_CC) || - ((to.to_flag & TOF_CC) != 0 && to.to_cc == tp->cc_recv)) && - ti->ti_seq == tp->rcv_nxt && - tiwin && tiwin == tp->snd_wnd && - tp->snd_nxt == tp->snd_max) { - - /* - * If last ACK falls within this segment's sequence numbers, - * record the timestamp. - * NOTE that the test is modified according to the latest - * proposal of the tcplw@cray.com list (Braden 1993/04/26). - */ - if ((to.to_flag & TOF_TS) != 0 && - SEQ_LEQ(ti->ti_seq, tp->last_ack_sent)) { - tp->ts_recent_age = tcp_now; - tp->ts_recent = to.to_tsval; - } - - if (ti->ti_len == 0) { - if (SEQ_GT(ti->ti_ack, tp->snd_una) && - SEQ_LEQ(ti->ti_ack, tp->snd_max) && - tp->snd_cwnd >= tp->snd_wnd && - tp->t_dupacks < tcprexmtthresh) { - /* - * this is a pure ack for outstanding data. - */ - ++tcpstat.tcps_predack; - if ((to.to_flag & TOF_TS) != 0) - tcp_xmit_timer(tp, - tcp_now - to.to_tsecr + 1); - else if (tp->t_rtt && - SEQ_GT(ti->ti_ack, tp->t_rtseq)) - tcp_xmit_timer(tp, tp->t_rtt); - acked = ti->ti_ack - tp->snd_una; - tcpstat.tcps_rcvackpack++; - tcpstat.tcps_rcvackbyte += acked; - sbdrop(&so->so_snd, acked); - tp->snd_una = ti->ti_ack; - m_freem(m); - - /* - * If all outstanding data are acked, stop - * retransmit timer, otherwise restart timer - * using current (possibly backed-off) value. - * If process is waiting for space, - * wakeup/selwakeup/signal. If data - * are ready to send, let tcp_output - * decide between more output or persist. - */ - if (tp->snd_una == tp->snd_max) - tp->t_timer[TCPT_REXMT] = 0; - else if (tp->t_timer[TCPT_PERSIST] == 0) - tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; - - if (so->so_snd.sb_flags & SB_NOTIFY) - sowwakeup(so); - if (so->so_snd.sb_cc) - (void) tcp_output(tp); - return; - } - } else if (ti->ti_ack == tp->snd_una && - tp->seg_next == (struct tcpiphdr *)tp && - ti->ti_len <= sbspace(&so->so_rcv)) { - /* - * this is a pure, in-sequence data packet - * with nothing on the reassembly queue and - * we have enough buffer space to take it. - */ - ++tcpstat.tcps_preddat; - tp->rcv_nxt += ti->ti_len; - tcpstat.tcps_rcvpack++; - tcpstat.tcps_rcvbyte += ti->ti_len; - /* - * Add data to socket buffer. - */ - sbappend(&so->so_rcv, m); - sorwakeup(so); -#ifdef TCP_ACK_HACK - /* - * If this is a short packet, then ACK now - with Nagel - * congestion avoidance sender won't send more until - * he gets an ACK. - */ - if (tiflags & TH_PUSH) { - tp->t_flags |= TF_ACKNOW; - tcp_output(tp); - } else { - tp->t_flags |= TF_DELACK; - } -#else - tp->t_flags |= TF_DELACK; -#endif - return; - } - } - - /* - * Calculate amount of space in receive window, - * and then do TCP input processing. - * Receive window is amount of space in rcv queue, - * but not less than advertised window. - */ - { int win; - - win = sbspace(&so->so_rcv); - if (win < 0) - win = 0; - tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); - } - - switch (tp->t_state) { - - /* - * If the state is LISTEN then ignore segment if it contains an RST. - * If the segment contains an ACK then it is bad and send a RST. - * If it does not contain a SYN then it is not interesting; drop it. - * If it is from this socket, drop it, it must be forged. - * Don't bother responding if the destination was a broadcast. - * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial - * tp->iss, and send a segment: - * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> - * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. - * Fill in remote peer address fields if not previously specified. - * Enter SYN_RECEIVED state, and process any other fields of this - * segment in this state. - */ - case TCPS_LISTEN: { - struct mbuf *am; - register struct sockaddr_in *sin; - - if (tiflags & TH_RST) - goto drop; - if (tiflags & TH_ACK) - goto dropwithreset; - if ((tiflags & TH_SYN) == 0) - goto drop; - if ((ti->ti_dport == ti->ti_sport) && - (ti->ti_dst.s_addr == ti->ti_src.s_addr)) - goto drop; - /* - * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN - * in_broadcast() should never return true on a received - * packet with M_BCAST not set. - */ - if (m->m_flags & (M_BCAST|M_MCAST) || - IN_MULTICAST(ntohl(ti->ti_dst.s_addr))) - goto drop; - am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ - if (am == NULL) - goto drop; - am->m_len = sizeof (struct sockaddr_in); - sin = mtod(am, struct sockaddr_in *); - sin->sin_family = AF_INET; - sin->sin_len = sizeof(*sin); - sin->sin_addr = ti->ti_src; - sin->sin_port = ti->ti_sport; - bzero((caddr_t)sin->sin_zero, sizeof(sin->sin_zero)); - laddr = inp->inp_laddr; - if (inp->inp_laddr.s_addr == INADDR_ANY) - inp->inp_laddr = ti->ti_dst; - if (in_pcbconnect(inp, am)) { - inp->inp_laddr = laddr; - (void) m_free(am); - goto drop; - } - (void) m_free(am); - tp->t_template = tcp_template(tp); - if (tp->t_template == 0) { - tp = tcp_drop(tp, ENOBUFS); - dropsocket = 0; /* socket is already gone */ - goto drop; - } - if ((taop = tcp_gettaocache(inp)) == NULL) { - taop = &tao_noncached; - bzero(taop, sizeof(*taop)); - } - tcp_dooptions(tp, optp, optlen, ti, &to); - if (iss) - tp->iss = iss; - else - tp->iss = tcp_iss; - tcp_iss += TCP_ISSINCR/4; - tp->irs = ti->ti_seq; - tcp_sendseqinit(tp); - tcp_rcvseqinit(tp); - /* - * Initialization of the tcpcb for transaction; - * set SND.WND = SEG.WND, - * initialize CCsend and CCrecv. - */ - tp->snd_wnd = tiwin; /* initial send-window */ - tp->cc_send = CC_INC(tcp_ccgen); - tp->cc_recv = to.to_cc; - /* - * Perform TAO test on incoming CC (SEG.CC) option, if any. - * - compare SEG.CC against cached CC from the same host, - * if any. - * - if SEG.CC > chached value, SYN must be new and is accepted - * immediately: save new CC in the cache, mark the socket - * connected, enter ESTABLISHED state, turn on flag to - * send a SYN in the next segment. - * A virtual advertised window is set in rcv_adv to - * initialize SWS prevention. Then enter normal segment - * processing: drop SYN, process data and FIN. - * - otherwise do a normal 3-way handshake. - */ - if ((to.to_flag & TOF_CC) != 0) { - if (taop->tao_cc != 0 && CC_GT(to.to_cc, taop->tao_cc)) { - taop->tao_cc = to.to_cc; - tp->t_state = TCPS_ESTABLISHED; - - /* - * If there is a FIN, or if there is data and the - * connection is local, then delay SYN,ACK(SYN) in - * the hope of piggy-backing it on a response - * segment. Otherwise must send ACK now in case - * the other side is slow starting. - */ - if ((tiflags & TH_FIN) || (ti->ti_len != 0 && - in_localaddr(inp->inp_faddr))) - tp->t_flags |= (TF_DELACK | TF_NEEDSYN); - else - tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); - - /* - * Limit the `virtual advertised window' to TCP_MAXWIN - * here. Even if we requested window scaling, it will - * become effective only later when our SYN is acked. - */ - tp->rcv_adv += min(tp->rcv_wnd, TCP_MAXWIN); - tcpstat.tcps_connects++; - soisconnected(so); - tp->t_timer[TCPT_KEEP] = tcp_keepinit; - dropsocket = 0; /* committed to socket */ - tcpstat.tcps_accepts++; - goto trimthenstep6; - } - /* else do standard 3-way handshake */ - } else { - /* - * No CC option, but maybe CC.NEW: - * invalidate cached value. - */ - taop->tao_cc = 0; - } - /* - * TAO test failed or there was no CC option, - * do a standard 3-way handshake. - */ - tp->t_flags |= TF_ACKNOW; - tp->t_state = TCPS_SYN_RECEIVED; - tp->t_timer[TCPT_KEEP] = tcp_keepinit; - dropsocket = 0; /* committed to socket */ - tcpstat.tcps_accepts++; - goto trimthenstep6; - } - - /* - * If the state is SYN_RECEIVED: - * if seg contains SYN/ACK, send a RST. - * if seg contains an ACK, but not for our SYN/ACK, send a RST. - */ - case TCPS_SYN_RECEIVED: - if (tiflags & TH_ACK) { - if (tiflags & TH_SYN) { - tcpstat.tcps_badsyn++; - goto dropwithreset; - } - if (SEQ_LEQ(ti->ti_ack, tp->snd_una) || - SEQ_GT(ti->ti_ack, tp->snd_max)) - goto dropwithreset; - } - break; - - /* - * If the state is SYN_SENT: - * if seg contains an ACK, but not for our SYN, drop the input. - * if seg contains a RST, then drop the connection. - * if seg does not contain SYN, then drop it. - * Otherwise this is an acceptable SYN segment - * initialize tp->rcv_nxt and tp->irs - * if seg contains ack then advance tp->snd_una - * if SYN has been acked change to ESTABLISHED else SYN_RCVD state - * arrange for segment to be acked (eventually) - * continue processing rest of data/controls, beginning with URG - */ - case TCPS_SYN_SENT: - if ((taop = tcp_gettaocache(inp)) == NULL) { - taop = &tao_noncached; - bzero(taop, sizeof(*taop)); - } - - if ((tiflags & TH_ACK) && - (SEQ_LEQ(ti->ti_ack, tp->iss) || - SEQ_GT(ti->ti_ack, tp->snd_max))) { - /* - * If we have a cached CCsent for the remote host, - * hence we haven't just crashed and restarted, - * do not send a RST. This may be a retransmission - * from the other side after our earlier ACK was lost. - * Our new SYN, when it arrives, will serve as the - * needed ACK. - */ - if (taop->tao_ccsent != 0) - goto drop; - else - goto dropwithreset; - } - if (tiflags & TH_RST) { - if (tiflags & TH_ACK) - tp = tcp_drop(tp, ECONNREFUSED); - goto drop; - } - if ((tiflags & TH_SYN) == 0) - goto drop; - tp->snd_wnd = ti->ti_win; /* initial send window */ - tp->cc_recv = to.to_cc; /* foreign CC */ - - tp->irs = ti->ti_seq; - tcp_rcvseqinit(tp); - if (tiflags & TH_ACK) { - /* - * Our SYN was acked. If segment contains CC.ECHO - * option, check it to make sure this segment really - * matches our SYN. If not, just drop it as old - * duplicate, but send an RST if we're still playing - * by the old rules. If no CC.ECHO option, make sure - * we don't get fooled into using T/TCP. - */ - if (to.to_flag & TOF_CCECHO) { - if (tp->cc_send != to.to_ccecho) { - if (taop->tao_ccsent != 0) - goto drop; - else - goto dropwithreset; - } - } else - tp->t_flags &= ~TF_RCVD_CC; - tcpstat.tcps_connects++; - soisconnected(so); - /* Do window scaling on this connection? */ - if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == - (TF_RCVD_SCALE|TF_REQ_SCALE)) { - tp->snd_scale = tp->requested_s_scale; - tp->rcv_scale = tp->request_r_scale; - } - /* Segment is acceptable, update cache if undefined. */ - if (taop->tao_ccsent == 0) - taop->tao_ccsent = to.to_ccecho; - - tp->rcv_adv += tp->rcv_wnd; - tp->snd_una++; /* SYN is acked */ - /* - * If there's data, delay ACK; if there's also a FIN - * ACKNOW will be turned on later. - */ - if (ti->ti_len != 0) - tp->t_flags |= TF_DELACK; - else - tp->t_flags |= TF_ACKNOW; - /* - * Received <SYN,ACK> in SYN_SENT[*] state. - * Transitions: - * SYN_SENT --> ESTABLISHED - * SYN_SENT* --> FIN_WAIT_1 - */ - if (tp->t_flags & TF_NEEDFIN) { - tp->t_state = TCPS_FIN_WAIT_1; - tp->t_flags &= ~TF_NEEDFIN; - tiflags &= ~TH_SYN; - } else { - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - } - } else { - /* - * Received initial SYN in SYN-SENT[*] state => simul- - * taneous open. If segment contains CC option and there is - * a cached CC, apply TAO test; if it succeeds, connection is - * half-synchronized. Otherwise, do 3-way handshake: - * SYN-SENT -> SYN-RECEIVED - * SYN-SENT* -> SYN-RECEIVED* - * If there was no CC option, clear cached CC value. - */ - tp->t_flags |= TF_ACKNOW; - tp->t_timer[TCPT_REXMT] = 0; - if (to.to_flag & TOF_CC) { - if (taop->tao_cc != 0 && - CC_GT(to.to_cc, taop->tao_cc)) { - /* - * update cache and make transition: - * SYN-SENT -> ESTABLISHED* - * SYN-SENT* -> FIN-WAIT-1* - */ - taop->tao_cc = to.to_cc; - if (tp->t_flags & TF_NEEDFIN) { - tp->t_state = TCPS_FIN_WAIT_1; - tp->t_flags &= ~TF_NEEDFIN; - } else { - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - } - tp->t_flags |= TF_NEEDSYN; - } else - tp->t_state = TCPS_SYN_RECEIVED; - } else { - /* CC.NEW or no option => invalidate cache */ - taop->tao_cc = 0; - tp->t_state = TCPS_SYN_RECEIVED; - } - } - -trimthenstep6: - /* - * Advance ti->ti_seq to correspond to first data byte. - * If data, trim to stay within window, - * dropping FIN if necessary. - */ - ti->ti_seq++; - if (ti->ti_len > tp->rcv_wnd) { - todrop = ti->ti_len - tp->rcv_wnd; - m_adj(m, -todrop); - ti->ti_len = tp->rcv_wnd; - tiflags &= ~TH_FIN; - tcpstat.tcps_rcvpackafterwin++; - tcpstat.tcps_rcvbyteafterwin += todrop; - } - tp->snd_wl1 = ti->ti_seq - 1; - tp->rcv_up = ti->ti_seq; - /* - * Client side of transaction: already sent SYN and data. - * If the remote host used T/TCP to validate the SYN, - * our data will be ACK'd; if so, enter normal data segment - * processing in the middle of step 5, ack processing. - * Otherwise, goto step 6. - */ - if (tiflags & TH_ACK) - goto process_ACK; - goto step6; - /* - * If the state is LAST_ACK or CLOSING or TIME_WAIT: - * if segment contains a SYN and CC [not CC.NEW] option: - * if state == TIME_WAIT and connection duration > MSL, - * drop packet and send RST; - * - * if SEG.CC > CCrecv then is new SYN, and can implicitly - * ack the FIN (and data) in retransmission queue. - * Complete close and delete TCPCB. Then reprocess - * segment, hoping to find new TCPCB in LISTEN state; - * - * else must be old SYN; drop it. - * else do normal processing. - */ - case TCPS_LAST_ACK: - case TCPS_CLOSING: - case TCPS_TIME_WAIT: - if ((tiflags & TH_SYN) && - (to.to_flag & TOF_CC) && tp->cc_recv != 0) { - if (tp->t_state == TCPS_TIME_WAIT && - tp->t_duration > TCPTV_MSL) - goto dropwithreset; - if (CC_GT(to.to_cc, tp->cc_recv)) { - tp = tcp_close(tp); - goto findpcb; - } - else - goto drop; - } - break; /* continue normal processing */ - } - - /* - * States other than LISTEN or SYN_SENT. - * First check timestamp, if present. - * Then check the connection count, if present. - * Then check that at least some bytes of segment are within - * receive window. If segment begins before rcv_nxt, - * drop leading data (and SYN); if nothing left, just ack. - * - * RFC 1323 PAWS: If we have a timestamp reply on this segment - * and it's less than ts_recent, drop it. - */ - if ((to.to_flag & TOF_TS) != 0 && (tiflags & TH_RST) == 0 && - tp->ts_recent && TSTMP_LT(to.to_tsval, tp->ts_recent)) { - - /* Check to see if ts_recent is over 24 days old. */ - if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) { - /* - * Invalidate ts_recent. If this segment updates - * ts_recent, the age will be reset later and ts_recent - * will get a valid value. If it does not, setting - * ts_recent to zero will at least satisfy the - * requirement that zero be placed in the timestamp - * echo reply when ts_recent isn't valid. The - * age isn't reset until we get a valid ts_recent - * because we don't want out-of-order segments to be - * dropped when ts_recent is old. - */ - tp->ts_recent = 0; - } else { - tcpstat.tcps_rcvduppack++; - tcpstat.tcps_rcvdupbyte += ti->ti_len; - tcpstat.tcps_pawsdrop++; - goto dropafterack; - } - } - - /* - * T/TCP mechanism - * If T/TCP was negotiated and the segment doesn't have CC, - * or if it's CC is wrong then drop the segment. - * RST segments do not have to comply with this. - */ - if ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) == (TF_REQ_CC|TF_RCVD_CC) && - ((to.to_flag & TOF_CC) == 0 || tp->cc_recv != to.to_cc) && - (tiflags & TH_RST) == 0) - goto dropafterack; - - todrop = tp->rcv_nxt - ti->ti_seq; - if (todrop > 0) { - if (tiflags & TH_SYN) { - tiflags &= ~TH_SYN; - ti->ti_seq++; - if (ti->ti_urp > 1) - ti->ti_urp--; - else - tiflags &= ~TH_URG; - todrop--; - } - /* - * Following if statement from Stevens, vol. 2, p. 960. - */ - if (todrop > ti->ti_len - || (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) { - /* - * Any valid FIN must be to the left of the window. - * At this point the FIN must be a duplicate or out - * of sequence; drop it. - */ - tiflags &= ~TH_FIN; - - /* - * Send an ACK to resynchronize and drop any data. - * But keep on processing for RST or ACK. - */ - tp->t_flags |= TF_ACKNOW; - todrop = ti->ti_len; - tcpstat.tcps_rcvduppack++; - tcpstat.tcps_rcvdupbyte += todrop; - } else { - tcpstat.tcps_rcvpartduppack++; - tcpstat.tcps_rcvpartdupbyte += todrop; - } - m_adj(m, todrop); - ti->ti_seq += todrop; - ti->ti_len -= todrop; - if (ti->ti_urp > todrop) - ti->ti_urp -= todrop; - else { - tiflags &= ~TH_URG; - ti->ti_urp = 0; - } - } - - /* - * If new data are received on a connection after the - * user processes are gone, then RST the other end. - */ - if ((so->so_state & SS_NOFDREF) && - tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) { - tp = tcp_close(tp); - tcpstat.tcps_rcvafterclose++; - goto dropwithreset; - } - - /* - * If segment ends after window, drop trailing data - * (and PUSH and FIN); if nothing left, just ACK. - */ - todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); - if (todrop > 0) { - tcpstat.tcps_rcvpackafterwin++; - if (todrop >= ti->ti_len) { - tcpstat.tcps_rcvbyteafterwin += ti->ti_len; - /* - * If a new connection request is received - * while in TIME_WAIT, drop the old connection - * and start over if the sequence numbers - * are above the previous ones. - */ - if (tiflags & TH_SYN && - tp->t_state == TCPS_TIME_WAIT && - SEQ_GT(ti->ti_seq, tp->rcv_nxt)) { - iss = tp->rcv_nxt + TCP_ISSINCR; - tp = tcp_close(tp); - goto findpcb; - } - /* - * If window is closed can only take segments at - * window edge, and have to drop data and PUSH from - * incoming segments. Continue processing, but - * remember to ack. Otherwise, drop segment - * and ack. - */ - if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) { - tp->t_flags |= TF_ACKNOW; - tcpstat.tcps_rcvwinprobe++; - } else - goto dropafterack; - } else - tcpstat.tcps_rcvbyteafterwin += todrop; - m_adj(m, -todrop); - ti->ti_len -= todrop; - tiflags &= ~(TH_PUSH|TH_FIN); - } - - /* - * If last ACK falls within this segment's sequence numbers, - * record its timestamp. - * NOTE that the test is modified according to the latest - * proposal of the tcplw@cray.com list (Braden 1993/04/26). - */ - if ((to.to_flag & TOF_TS) != 0 && - SEQ_LEQ(ti->ti_seq, tp->last_ack_sent)) { - tp->ts_recent_age = tcp_now; - tp->ts_recent = to.to_tsval; - } - - /* - * If the RST bit is set examine the state: - * SYN_RECEIVED STATE: - * If passive open, return to LISTEN state. - * If active open, inform user that connection was refused. - * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: - * Inform user that connection was reset, and close tcb. - * CLOSING, LAST_ACK, TIME_WAIT STATES - * Close the tcb. - */ - if (tiflags&TH_RST) switch (tp->t_state) { - - case TCPS_SYN_RECEIVED: - so->so_error = ECONNREFUSED; - goto close; - - case TCPS_ESTABLISHED: - case TCPS_FIN_WAIT_1: - case TCPS_FIN_WAIT_2: - case TCPS_CLOSE_WAIT: - so->so_error = ECONNRESET; - close: - tp->t_state = TCPS_CLOSED; - tcpstat.tcps_drops++; - tp = tcp_close(tp); - goto drop; - - case TCPS_CLOSING: - case TCPS_LAST_ACK: - case TCPS_TIME_WAIT: - tp = tcp_close(tp); - goto drop; - } - - /* - * If a SYN is in the window, then this is an - * error and we send an RST and drop the connection. - */ - if (tiflags & TH_SYN) { - tp = tcp_drop(tp, ECONNRESET); - goto dropwithreset; - } - - /* - * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN - * flag is on (half-synchronized state), then queue data for - * later processing; else drop segment and return. - */ - if ((tiflags & TH_ACK) == 0) { - if (tp->t_state == TCPS_SYN_RECEIVED || - (tp->t_flags & TF_NEEDSYN)) - goto step6; - else - goto drop; - } - - /* - * Ack processing. - */ - switch (tp->t_state) { - - /* - * In SYN_RECEIVED state, the ack ACKs our SYN, so enter - * ESTABLISHED state and continue processing. - * The ACK was checked above. - */ - case TCPS_SYN_RECEIVED: - - tcpstat.tcps_connects++; - soisconnected(so); - /* Do window scaling? */ - if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == - (TF_RCVD_SCALE|TF_REQ_SCALE)) { - tp->snd_scale = tp->requested_s_scale; - tp->rcv_scale = tp->request_r_scale; - } - /* - * Upon successful completion of 3-way handshake, - * update cache.CC if it was undefined, pass any queued - * data to the user, and advance state appropriately. - */ - if ((taop = tcp_gettaocache(inp)) != NULL && - taop->tao_cc == 0) - taop->tao_cc = tp->cc_recv; - - /* - * Make transitions: - * SYN-RECEIVED -> ESTABLISHED - * SYN-RECEIVED* -> FIN-WAIT-1 - */ - if (tp->t_flags & TF_NEEDFIN) { - tp->t_state = TCPS_FIN_WAIT_1; - tp->t_flags &= ~TF_NEEDFIN; - } else { - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - } - /* - * If segment contains data or ACK, will call tcp_reass() - * later; if not, do so now to pass queued data to user. - */ - if (ti->ti_len == 0 && (tiflags & TH_FIN) == 0) - (void) tcp_reass(tp, (struct tcpiphdr *)0, - (struct mbuf *)0); - tp->snd_wl1 = ti->ti_seq - 1; - /* fall into ... */ - - /* - * In ESTABLISHED state: drop duplicate ACKs; ACK out of range - * ACKs. If the ack is in the range - * tp->snd_una < ti->ti_ack <= tp->snd_max - * then advance tp->snd_una to ti->ti_ack and drop - * data from the retransmission queue. If this ACK reflects - * more up to date window information we update our window information. - */ - case TCPS_ESTABLISHED: - case TCPS_FIN_WAIT_1: - case TCPS_FIN_WAIT_2: - case TCPS_CLOSE_WAIT: - case TCPS_CLOSING: - case TCPS_LAST_ACK: - case TCPS_TIME_WAIT: - - if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) { - if (ti->ti_len == 0 && tiwin == tp->snd_wnd) { - tcpstat.tcps_rcvdupack++; - /* - * If we have outstanding data (other than - * a window probe), this is a completely - * duplicate ack (ie, window info didn't - * change), the ack is the biggest we've - * seen and we've seen exactly our rexmt - * threshhold of them, assume a packet - * has been dropped and retransmit it. - * Kludge snd_nxt & the congestion - * window so we send only this one - * packet. - * - * We know we're losing at the current - * window size so do congestion avoidance - * (set ssthresh to half the current window - * and pull our congestion window back to - * the new ssthresh). - * - * Dup acks mean that packets have left the - * network (they're now cached at the receiver) - * so bump cwnd by the amount in the receiver - * to keep a constant cwnd packets in the - * network. - */ - if (tp->t_timer[TCPT_REXMT] == 0 || - ti->ti_ack != tp->snd_una) - tp->t_dupacks = 0; - else if (++tp->t_dupacks == tcprexmtthresh) { - tcp_seq onxt = tp->snd_nxt; - u_int win = - min(tp->snd_wnd, tp->snd_cwnd) / 2 / - tp->t_maxseg; - - if (win < 2) - win = 2; - tp->snd_ssthresh = win * tp->t_maxseg; - tp->t_timer[TCPT_REXMT] = 0; - tp->t_rtt = 0; - tp->snd_nxt = ti->ti_ack; - tp->snd_cwnd = tp->t_maxseg; - (void) tcp_output(tp); - tp->snd_cwnd = tp->snd_ssthresh + - tp->t_maxseg * tp->t_dupacks; - if (SEQ_GT(onxt, tp->snd_nxt)) - tp->snd_nxt = onxt; - goto drop; - } else if (tp->t_dupacks > tcprexmtthresh) { - tp->snd_cwnd += tp->t_maxseg; - (void) tcp_output(tp); - goto drop; - } - } else - tp->t_dupacks = 0; - break; - } - /* - * If the congestion window was inflated to account - * for the other side's cached packets, retract it. - */ - if (tp->t_dupacks >= tcprexmtthresh && - tp->snd_cwnd > tp->snd_ssthresh) - tp->snd_cwnd = tp->snd_ssthresh; - tp->t_dupacks = 0; - if (SEQ_GT(ti->ti_ack, tp->snd_max)) { - tcpstat.tcps_rcvacktoomuch++; - goto dropafterack; - } - /* - * If we reach this point, ACK is not a duplicate, - * i.e., it ACKs something we sent. - */ - if (tp->t_flags & TF_NEEDSYN) { - /* - * T/TCP: Connection was half-synchronized, and our - * SYN has been ACK'd (so connection is now fully - * synchronized). Go to non-starred state, - * increment snd_una for ACK of SYN, and check if - * we can do window scaling. - */ - tp->t_flags &= ~TF_NEEDSYN; - tp->snd_una++; - /* Do window scaling? */ - if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == - (TF_RCVD_SCALE|TF_REQ_SCALE)) { - tp->snd_scale = tp->requested_s_scale; - tp->rcv_scale = tp->request_r_scale; - } - } - -process_ACK: - acked = ti->ti_ack - tp->snd_una; - tcpstat.tcps_rcvackpack++; - tcpstat.tcps_rcvackbyte += acked; - - /* - * If we have a timestamp reply, update smoothed - * round trip time. If no timestamp is present but - * transmit timer is running and timed sequence - * number was acked, update smoothed round trip time. - * Since we now have an rtt measurement, cancel the - * timer backoff (cf., Phil Karn's retransmit alg.). - * Recompute the initial retransmit timer. - */ - if (to.to_flag & TOF_TS) - tcp_xmit_timer(tp, tcp_now - to.to_tsecr + 1); - else if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq)) - tcp_xmit_timer(tp,tp->t_rtt); - - /* - * If all outstanding data is acked, stop retransmit - * timer and remember to restart (more output or persist). - * If there is more data to be acked, restart retransmit - * timer, using current (possibly backed-off) value. - */ - if (ti->ti_ack == tp->snd_max) { - tp->t_timer[TCPT_REXMT] = 0; - needoutput = 1; - } else if (tp->t_timer[TCPT_PERSIST] == 0) - tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; - - /* - * If no data (only SYN) was ACK'd, - * skip rest of ACK processing. - */ - if (acked == 0) - goto step6; - - /* - * When new data is acked, open the congestion window. - * If the window gives us less than ssthresh packets - * in flight, open exponentially (maxseg per packet). - * Otherwise open linearly: maxseg per window - * (maxseg^2 / cwnd per packet). - */ - { - register u_int cw = tp->snd_cwnd; - register u_int incr = tp->t_maxseg; - - if (cw > tp->snd_ssthresh) - incr = incr * incr / cw; - tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale); - } - if (acked > so->so_snd.sb_cc) { - tp->snd_wnd -= so->so_snd.sb_cc; - sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); - ourfinisacked = 1; - } else { - sbdrop(&so->so_snd, acked); - tp->snd_wnd -= acked; - ourfinisacked = 0; - } - if (so->so_snd.sb_flags & SB_NOTIFY) - sowwakeup(so); - tp->snd_una = ti->ti_ack; - if (SEQ_LT(tp->snd_nxt, tp->snd_una)) - tp->snd_nxt = tp->snd_una; - - switch (tp->t_state) { - - /* - * In FIN_WAIT_1 STATE in addition to the processing - * for the ESTABLISHED state if our FIN is now acknowledged - * then enter FIN_WAIT_2. - */ - case TCPS_FIN_WAIT_1: - if (ourfinisacked) { - /* - * If we can't receive any more - * data, then closing user can proceed. - * Starting the timer is contrary to the - * specification, but if we don't get a FIN - * we'll hang forever. - */ - if (so->so_state & SS_CANTRCVMORE) { - soisdisconnected(so); - tp->t_timer[TCPT_2MSL] = tcp_maxidle; - } - tp->t_state = TCPS_FIN_WAIT_2; - } - break; - - /* - * In CLOSING STATE in addition to the processing for - * the ESTABLISHED state if the ACK acknowledges our FIN - * then enter the TIME-WAIT state, otherwise ignore - * the segment. - */ - case TCPS_CLOSING: - if (ourfinisacked) { - tp->t_state = TCPS_TIME_WAIT; - tcp_canceltimers(tp); - /* Shorten TIME_WAIT [RFC-1644, p.28] */ - if (tp->cc_recv != 0 && - tp->t_duration < TCPTV_MSL) - tp->t_timer[TCPT_2MSL] = - tp->t_rxtcur * TCPTV_TWTRUNC; - else - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - soisdisconnected(so); - } - break; - - /* - * In LAST_ACK, we may still be waiting for data to drain - * and/or to be acked, as well as for the ack of our FIN. - * If our FIN is now acknowledged, delete the TCB, - * enter the closed state and return. - */ - case TCPS_LAST_ACK: - if (ourfinisacked) { - tp = tcp_close(tp); - goto drop; - } - break; - - /* - * In TIME_WAIT state the only thing that should arrive - * is a retransmission of the remote FIN. Acknowledge - * it and restart the finack timer. - */ - case TCPS_TIME_WAIT: - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - goto dropafterack; - } - } - -step6: - /* - * Update window information. - * Don't look at window if no ACK: TAC's send garbage on first SYN. - */ - if ((tiflags & TH_ACK) && - (SEQ_LT(tp->snd_wl1, ti->ti_seq) || - (tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) || - (tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) { - /* keep track of pure window updates */ - if (ti->ti_len == 0 && - tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd) - tcpstat.tcps_rcvwinupd++; - tp->snd_wnd = tiwin; - tp->snd_wl1 = ti->ti_seq; - tp->snd_wl2 = ti->ti_ack; - if (tp->snd_wnd > tp->max_sndwnd) - tp->max_sndwnd = tp->snd_wnd; - needoutput = 1; - } - - /* - * Process segments with URG. - */ - if ((tiflags & TH_URG) && ti->ti_urp && - TCPS_HAVERCVDFIN(tp->t_state) == 0) { - /* - * This is a kludge, but if we receive and accept - * random urgent pointers, we'll crash in - * soreceive. It's hard to imagine someone - * actually wanting to send this much urgent data. - */ - if (ti->ti_urp + so->so_rcv.sb_cc > sb_max) { - ti->ti_urp = 0; /* XXX */ - tiflags &= ~TH_URG; /* XXX */ - goto dodata; /* XXX */ - } - /* - * If this segment advances the known urgent pointer, - * then mark the data stream. This should not happen - * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since - * a FIN has been received from the remote side. - * In these states we ignore the URG. - * - * According to RFC961 (Assigned Protocols), - * the urgent pointer points to the last octet - * of urgent data. We continue, however, - * to consider it to indicate the first octet - * of data past the urgent section as the original - * spec states (in one of two places). - */ - if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) { - tp->rcv_up = ti->ti_seq + ti->ti_urp; - so->so_oobmark = so->so_rcv.sb_cc + - (tp->rcv_up - tp->rcv_nxt) - 1; - if (so->so_oobmark == 0) - so->so_state |= SS_RCVATMARK; - sohasoutofband(so); - tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); - } - /* - * Remove out of band data so doesn't get presented to user. - * This can happen independent of advancing the URG pointer, - * but if two URG's are pending at once, some out-of-band - * data may creep in... ick. - */ - if (ti->ti_urp <= (u_long)ti->ti_len -#ifdef SO_OOBINLINE - && (so->so_options & SO_OOBINLINE) == 0 -#endif - ) - tcp_pulloutofband(so, ti, m); - } else - /* - * If no out of band data is expected, - * pull receive urgent pointer along - * with the receive window. - */ - if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) - tp->rcv_up = tp->rcv_nxt; -dodata: /* XXX */ - - /* - * Process the segment text, merging it into the TCP sequencing queue, - * and arranging for acknowledgment of receipt if necessary. - * This process logically involves adjusting tp->rcv_wnd as data - * is presented to the user (this happens in tcp_usrreq.c, - * case PRU_RCVD). If a FIN has already been received on this - * connection then we just ignore the text. - */ - if ((ti->ti_len || (tiflags&TH_FIN)) && - TCPS_HAVERCVDFIN(tp->t_state) == 0) { - TCP_REASS(tp, ti, m, so, tiflags); - /* - * Note the amount of data that peer has sent into - * our window, in order to estimate the sender's - * buffer size. - */ - len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); - } else { - m_freem(m); - tiflags &= ~TH_FIN; - } - - /* - * If FIN is received ACK the FIN and let the user know - * that the connection is closing. - */ - if (tiflags & TH_FIN) { - if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { - socantrcvmore(so); - /* - * If connection is half-synchronized - * (ie NEEDSYN flag on) then delay ACK, - * so it may be piggybacked when SYN is sent. - * Otherwise, since we received a FIN then no - * more input can be expected, send ACK now. - */ - if (tp->t_flags & TF_NEEDSYN) - tp->t_flags |= TF_DELACK; - else - tp->t_flags |= TF_ACKNOW; - tp->rcv_nxt++; - } - switch (tp->t_state) { - - /* - * In SYN_RECEIVED and ESTABLISHED STATES - * enter the CLOSE_WAIT state. - */ - case TCPS_SYN_RECEIVED: - case TCPS_ESTABLISHED: - tp->t_state = TCPS_CLOSE_WAIT; - break; - - /* - * If still in FIN_WAIT_1 STATE FIN has not been acked so - * enter the CLOSING state. - */ - case TCPS_FIN_WAIT_1: - tp->t_state = TCPS_CLOSING; - break; - - /* - * In FIN_WAIT_2 state enter the TIME_WAIT state, - * starting the time-wait timer, turning off the other - * standard timers. - */ - case TCPS_FIN_WAIT_2: - tp->t_state = TCPS_TIME_WAIT; - tcp_canceltimers(tp); - /* Shorten TIME_WAIT [RFC-1644, p.28] */ - if (tp->cc_recv != 0 && - tp->t_duration < TCPTV_MSL) { - tp->t_timer[TCPT_2MSL] = - tp->t_rxtcur * TCPTV_TWTRUNC; - /* For transaction client, force ACK now. */ - tp->t_flags |= TF_ACKNOW; - } - else - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - soisdisconnected(so); - break; - - /* - * In TIME_WAIT state restart the 2 MSL time_wait timer. - */ - case TCPS_TIME_WAIT: - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - break; - } - } -#ifdef TCPDEBUG - if (so->so_options & SO_DEBUG) - tcp_trace(TA_INPUT, ostate, tp, &tcp_saveti, 0); -#endif - - /* - * Return any desired output. - */ - if (needoutput || (tp->t_flags & TF_ACKNOW)) - (void) tcp_output(tp); - return; - -dropafterack: - /* - * Generate an ACK dropping incoming segment if it occupies - * sequence space, where the ACK reflects our state. - */ - if (tiflags & TH_RST) - goto drop; -#ifdef TCPDEBUG - if (so->so_options & SO_DEBUG) - tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); -#endif - m_freem(m); - tp->t_flags |= TF_ACKNOW; - (void) tcp_output(tp); - return; - -dropwithreset: - /* - * Generate a RST, dropping incoming segment. - * Make ACK acceptable to originator of segment. - * Don't bother to respond if destination was broadcast/multicast. - */ - if ((tiflags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST) || - IN_MULTICAST(ntohl(ti->ti_dst.s_addr))) - goto drop; -#ifdef TCPDEBUG - if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) - tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); -#endif - if (tiflags & TH_ACK) - tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST); - else { - if (tiflags & TH_SYN) - ti->ti_len++; - tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0, - TH_RST|TH_ACK); - } - /* destroy temporarily created socket */ - if (dropsocket) - (void) soabort(so); - return; - -drop: - /* - * Drop space held by incoming segment and return. - */ -#ifdef TCPDEBUG - if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) - tcp_trace(TA_DROP, ostate, tp, &tcp_saveti, 0); -#endif - m_freem(m); - /* destroy temporarily created socket */ - if (dropsocket) - (void) soabort(so); - return; -#ifndef TUBA_INCLUDE -} - -static void -tcp_dooptions(tp, cp, cnt, ti, to) - struct tcpcb *tp; - u_char *cp; - int cnt; - struct tcpiphdr *ti; - struct tcpopt *to; -{ - u_short mss = 0; - int opt, optlen; - - for (; cnt > 0; cnt -= optlen, cp += optlen) { - opt = cp[0]; - if (opt == TCPOPT_EOL) - break; - if (opt == TCPOPT_NOP) - optlen = 1; - else { - optlen = cp[1]; - if (optlen <= 0) - break; - } - switch (opt) { - - default: - continue; - - case TCPOPT_MAXSEG: - if (optlen != TCPOLEN_MAXSEG) - continue; - if (!(ti->ti_flags & TH_SYN)) - continue; - bcopy((char *) cp + 2, (char *) &mss, sizeof(mss)); - NTOHS(mss); - break; - - case TCPOPT_WINDOW: - if (optlen != TCPOLEN_WINDOW) - continue; - if (!(ti->ti_flags & TH_SYN)) - continue; - tp->t_flags |= TF_RCVD_SCALE; - tp->requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT); - break; - - case TCPOPT_TIMESTAMP: - if (optlen != TCPOLEN_TIMESTAMP) - continue; - to->to_flag |= TOF_TS; - bcopy((char *)cp + 2, - (char *)&to->to_tsval, sizeof(to->to_tsval)); - NTOHL(to->to_tsval); - bcopy((char *)cp + 6, - (char *)&to->to_tsecr, sizeof(to->to_tsecr)); - NTOHL(to->to_tsecr); - - /* - * A timestamp received in a SYN makes - * it ok to send timestamp requests and replies. - */ - if (ti->ti_flags & TH_SYN) { - tp->t_flags |= TF_RCVD_TSTMP; - tp->ts_recent = to->to_tsval; - tp->ts_recent_age = tcp_now; - } - break; - case TCPOPT_CC: - if (optlen != TCPOLEN_CC) - continue; - to->to_flag |= TOF_CC; - bcopy((char *)cp + 2, - (char *)&to->to_cc, sizeof(to->to_cc)); - NTOHL(to->to_cc); - /* - * A CC or CC.new option received in a SYN makes - * it ok to send CC in subsequent segments. - */ - if (ti->ti_flags & TH_SYN) - tp->t_flags |= TF_RCVD_CC; - break; - case TCPOPT_CCNEW: - if (optlen != TCPOLEN_CC) - continue; - if (!(ti->ti_flags & TH_SYN)) - continue; - to->to_flag |= TOF_CCNEW; - bcopy((char *)cp + 2, - (char *)&to->to_cc, sizeof(to->to_cc)); - NTOHL(to->to_cc); - /* - * A CC or CC.new option received in a SYN makes - * it ok to send CC in subsequent segments. - */ - tp->t_flags |= TF_RCVD_CC; - break; - case TCPOPT_CCECHO: - if (optlen != TCPOLEN_CC) - continue; - if (!(ti->ti_flags & TH_SYN)) - continue; - to->to_flag |= TOF_CCECHO; - bcopy((char *)cp + 2, - (char *)&to->to_ccecho, sizeof(to->to_ccecho)); - NTOHL(to->to_ccecho); - break; - } - } - if (ti->ti_flags & TH_SYN) - tcp_mss(tp, mss); /* sets t_maxseg */ -} - -/* - * Pull out of band byte out of a segment so - * it doesn't appear in the user's data queue. - * It is still reflected in the segment length for - * sequencing purposes. - */ -static void -tcp_pulloutofband(so, ti, m) - struct socket *so; - struct tcpiphdr *ti; - register struct mbuf *m; -{ - int cnt = ti->ti_urp - 1; - - while (cnt >= 0) { - if (m->m_len > cnt) { - char *cp = mtod(m, caddr_t) + cnt; - struct tcpcb *tp = sototcpcb(so); - - tp->t_iobc = *cp; - tp->t_oobflags |= TCPOOB_HAVEDATA; - bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); - m->m_len--; - return; - } - cnt -= m->m_len; - m = m->m_next; - if (m == 0) - break; - } - panic("tcp_pulloutofband"); -} - -/* - * Collect new round-trip time estimate - * and update averages and current timeout. - */ -static void -tcp_xmit_timer(tp, rtt) - register struct tcpcb *tp; - short rtt; -{ - register int delta; - - tcpstat.tcps_rttupdated++; - tp->t_rttupdated++; - if (tp->t_srtt != 0) { - /* - * srtt is stored as fixed point with 5 bits after the - * binary point (i.e., scaled by 8). The following magic - * is equivalent to the smoothing algorithm in rfc793 with - * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed - * point). Adjust rtt to origin 0. - */ - delta = ((rtt - 1) << TCP_DELTA_SHIFT) - - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); - - if ((tp->t_srtt += delta) <= 0) - tp->t_srtt = 1; - - /* - * We accumulate a smoothed rtt variance (actually, a - * smoothed mean difference), then set the retransmit - * timer to smoothed rtt + 4 times the smoothed variance. - * rttvar is stored as fixed point with 4 bits after the - * binary point (scaled by 16). The following is - * equivalent to rfc793 smoothing with an alpha of .75 - * (rttvar = rttvar*3/4 + |delta| / 4). This replaces - * rfc793's wired-in beta. - */ - if (delta < 0) - delta = -delta; - delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); - if ((tp->t_rttvar += delta) <= 0) - tp->t_rttvar = 1; - } else { - /* - * No rtt measurement yet - use the unsmoothed rtt. - * Set the variance to half the rtt (so our first - * retransmit happens at 3*rtt). - */ - tp->t_srtt = rtt << TCP_RTT_SHIFT; - tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); - } - tp->t_rtt = 0; - tp->t_rxtshift = 0; - - /* - * the retransmit should happen at rtt + 4 * rttvar. - * Because of the way we do the smoothing, srtt and rttvar - * will each average +1/2 tick of bias. When we compute - * the retransmit timer, we want 1/2 tick of rounding and - * 1 extra tick because of +-1/2 tick uncertainty in the - * firing of the timer. The bias will give us exactly the - * 1.5 tick we need. But, because the bias is - * statistical, we have to test that we don't drop below - * the minimum feasible timer (which is 2 ticks). - */ - TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), - max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); - - /* - * We received an ack for a packet that wasn't retransmitted; - * it is probably safe to discard any error indications we've - * received recently. This isn't quite right, but close enough - * for now (a route might have failed after we sent a segment, - * and the return path might not be symmetrical). - */ - tp->t_softerror = 0; -} - -/* - * Determine a reasonable value for maxseg size. - * If the route is known, check route for mtu. - * If none, use an mss that can be handled on the outgoing - * interface without forcing IP to fragment; if bigger than - * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES - * to utilize large mbufs. If no route is found, route has no mtu, - * or the destination isn't local, use a default, hopefully conservative - * size (usually 512 or the default IP max size, but no more than the mtu - * of the interface), as we can't discover anything about intervening - * gateways or networks. We also initialize the congestion/slow start - * window to be a single segment if the destination isn't local. - * While looking at the routing entry, we also initialize other path-dependent - * parameters from pre-set or cached values in the routing entry. - * - * Also take into account the space needed for options that we - * send regularly. Make maxseg shorter by that amount to assure - * that we can send maxseg amount of data even when the options - * are present. Store the upper limit of the length of options plus - * data in maxopd. - * - * NOTE that this routine is only called when we process an incoming - * segment, for outgoing segments only tcp_mssopt is called. - * - * In case of T/TCP, we call this routine during implicit connection - * setup as well (offer = -1), to initialize maxseg from the cached - * MSS of our peer. - */ -void -tcp_mss(tp, offer) - struct tcpcb *tp; - int offer; -{ - register struct rtentry *rt; - struct ifnet *ifp; - register int rtt, mss; - u_long bufsize; - struct inpcb *inp; - struct socket *so; - struct rmxp_tao *taop; - int origoffer = offer; - - inp = tp->t_inpcb; - if ((rt = tcp_rtlookup(inp)) == NULL) { - tp->t_maxopd = tp->t_maxseg = tcp_mssdflt; - return; - } - ifp = rt->rt_ifp; - so = inp->inp_socket; - - taop = rmx_taop(rt->rt_rmx); - /* - * Offer == -1 means that we didn't receive SYN yet, - * use cached value in that case; - */ - if (offer == -1) - offer = taop->tao_mssopt; - /* - * Offer == 0 means that there was no MSS on the SYN segment, - * in this case we use tcp_mssdflt. - */ - if (offer == 0) - offer = tcp_mssdflt; - else - /* - * Sanity check: make sure that maxopd will be large - * enough to allow some data on segments even is the - * all the option space is used (40bytes). Otherwise - * funny things may happen in tcp_output. - */ - offer = max(offer, 64); - taop->tao_mssopt = offer; - - /* - * While we're here, check if there's an initial rtt - * or rttvar. Convert from the route-table units - * to scaled multiples of the slow timeout timer. - */ - if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { - /* - * XXX the lock bit for RTT indicates that the value - * is also a minimum value; this is subject to time. - */ - if (rt->rt_rmx.rmx_locks & RTV_RTT) - tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ); - tp->t_srtt = rtt / (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); - tcpstat.tcps_usedrtt++; - if (rt->rt_rmx.rmx_rttvar) { - tp->t_rttvar = rt->rt_rmx.rmx_rttvar / - (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); - tcpstat.tcps_usedrttvar++; - } else { - /* default variation is +- 1 rtt */ - tp->t_rttvar = - tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; - } - TCPT_RANGESET(tp->t_rxtcur, - ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, - tp->t_rttmin, TCPTV_REXMTMAX); - } - /* - * if there's an mtu associated with the route, use it - */ - if (rt->rt_rmx.rmx_mtu) - mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); - else - { - mss = ifp->if_mtu - sizeof(struct tcpiphdr); - if (!in_localaddr(inp->inp_faddr)) - mss = min(mss, tcp_mssdflt); - } - mss = min(mss, offer); - /* - * maxopd stores the maximum length of data AND options - * in a segment; maxseg is the amount of data in a normal - * segment. We need to store this value (maxopd) apart - * from maxseg, because now every segment carries options - * and thus we normally have somewhat less data in segments. - */ - tp->t_maxopd = mss; - - /* - * In case of T/TCP, origoffer==-1 indicates, that no segments - * were received yet. In this case we just guess, otherwise - * we do the same as before T/TCP. - */ - if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && - (origoffer == -1 || - (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) - mss -= TCPOLEN_TSTAMP_APPA; - if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && - (origoffer == -1 || - (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)) - mss -= TCPOLEN_CC_APPA; - -#if (MCLBYTES & (MCLBYTES - 1)) == 0 - if (mss > MCLBYTES) - mss &= ~(MCLBYTES-1); -#else - if (mss > MCLBYTES) - mss = mss / MCLBYTES * MCLBYTES; -#endif - /* - * If there's a pipesize, change the socket buffer - * to that size. Make the socket buffers an integral - * number of mss units; if the mss is larger than - * the socket buffer, decrease the mss. - */ -#ifdef RTV_SPIPE - if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0) -#endif - bufsize = so->so_snd.sb_hiwat; - if (bufsize < mss) - mss = bufsize; - else { - bufsize = roundup(bufsize, mss); - if (bufsize > sb_max) - bufsize = sb_max; - (void)sbreserve(&so->so_snd, bufsize); - } - tp->t_maxseg = mss; - -#ifdef RTV_RPIPE - if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0) -#endif - bufsize = so->so_rcv.sb_hiwat; - if (bufsize > mss) { - bufsize = roundup(bufsize, mss); - if (bufsize > sb_max) - bufsize = sb_max; - (void)sbreserve(&so->so_rcv, bufsize); - } - /* - * Don't force slow-start on local network. - */ - if (!in_localaddr(inp->inp_faddr)) - tp->snd_cwnd = mss; - - if (rt->rt_rmx.rmx_ssthresh) { - /* - * There's some sort of gateway or interface - * buffer limit on the path. Use this to set - * the slow start threshhold, but set the - * threshold to no less than 2*mss. - */ - tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); - tcpstat.tcps_usedssthresh++; - } -} - -/* - * Determine the MSS option to send on an outgoing SYN. - */ -int -tcp_mssopt(tp) - struct tcpcb *tp; -{ - struct rtentry *rt; - - rt = tcp_rtlookup(tp->t_inpcb); - if (rt == NULL) - return tcp_mssdflt; - - return rt->rt_ifp->if_mtu - sizeof(struct tcpiphdr); -} -#endif /* TUBA_INCLUDE */ |