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/*
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 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994
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 *        The Regents of the University of California.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
13 2f5f8996 aliguori
 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 f0cbd3ec bellard
 * SUCH DAMAGE.
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 *
29 f0cbd3ec bellard
 *        @(#)tcp_input.c        8.5 (Berkeley) 4/10/94
30 f0cbd3ec bellard
 * tcp_input.c,v 1.10 1994/10/13 18:36:32 wollman Exp
31 f0cbd3ec bellard
 */
32 f0cbd3ec bellard
33 f0cbd3ec bellard
/*
34 f0cbd3ec bellard
 * Changes and additions relating to SLiRP
35 f0cbd3ec bellard
 * Copyright (c) 1995 Danny Gasparovski.
36 5fafdf24 ths
 *
37 5fafdf24 ths
 * Please read the file COPYRIGHT for the
38 f0cbd3ec bellard
 * terms and conditions of the copyright.
39 f0cbd3ec bellard
 */
40 f0cbd3ec bellard
41 f0cbd3ec bellard
#include <slirp.h>
42 f0cbd3ec bellard
#include "ip_icmp.h"
43 f0cbd3ec bellard
44 f0cbd3ec bellard
struct socket tcb;
45 f0cbd3ec bellard
46 9634d903 blueswir1
#define        TCPREXMTTHRESH 3
47 f0cbd3ec bellard
struct        socket *tcp_last_so = &tcb;
48 f0cbd3ec bellard
49 f0cbd3ec bellard
tcp_seq tcp_iss;                /* tcp initial send seq # */
50 f0cbd3ec bellard
51 f0cbd3ec bellard
#define TCP_PAWS_IDLE        (24 * 24 * 60 * 60 * PR_SLOWHZ)
52 f0cbd3ec bellard
53 f0cbd3ec bellard
/* for modulo comparisons of timestamps */
54 f0cbd3ec bellard
#define TSTMP_LT(a,b)        ((int)((a)-(b)) < 0)
55 f0cbd3ec bellard
#define TSTMP_GEQ(a,b)        ((int)((a)-(b)) >= 0)
56 f0cbd3ec bellard
57 f0cbd3ec bellard
/*
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 * Insert segment ti into reassembly queue of tcp with
59 f0cbd3ec bellard
 * control block tp.  Return TH_FIN if reassembly now includes
60 f0cbd3ec bellard
 * a segment with FIN.  The macro form does the common case inline
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 * (segment is the next to be received on an established connection,
62 f0cbd3ec bellard
 * and the queue is empty), avoiding linkage into and removal
63 f0cbd3ec bellard
 * from the queue and repetition of various conversions.
64 f0cbd3ec bellard
 * Set DELACK for segments received in order, but ack immediately
65 f0cbd3ec bellard
 * when segments are out of order (so fast retransmit can work).
66 f0cbd3ec bellard
 */
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#ifdef TCP_ACK_HACK
68 f0cbd3ec bellard
#define TCP_REASS(tp, ti, m, so, flags) {\
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       if ((ti)->ti_seq == (tp)->rcv_nxt && \
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           tcpfrag_list_empty(tp) && \
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           (tp)->t_state == TCPS_ESTABLISHED) {\
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               if (ti->ti_flags & TH_PUSH) \
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                       tp->t_flags |= TF_ACKNOW; \
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               else \
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                       tp->t_flags |= TF_DELACK; \
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               (tp)->rcv_nxt += (ti)->ti_len; \
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               flags = (ti)->ti_flags & TH_FIN; \
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               STAT(tcpstat.tcps_rcvpack++);         \
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               STAT(tcpstat.tcps_rcvbyte += (ti)->ti_len);   \
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               if (so->so_emu) { \
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                       if (tcp_emu((so),(m))) sbappend((so), (m)); \
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               } else \
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                              sbappend((so), (m)); \
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/*               sorwakeup(so); */ \
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        } else {\
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               (flags) = tcp_reass((tp), (ti), (m)); \
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               tp->t_flags |= TF_ACKNOW; \
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       } \
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}
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#else
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#define        TCP_REASS(tp, ti, m, so, flags) { \
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        if ((ti)->ti_seq == (tp)->rcv_nxt && \
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        tcpfrag_list_empty(tp) && \
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            (tp)->t_state == TCPS_ESTABLISHED) { \
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                tp->t_flags |= TF_DELACK; \
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                (tp)->rcv_nxt += (ti)->ti_len; \
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                flags = (ti)->ti_flags & TH_FIN; \
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                STAT(tcpstat.tcps_rcvpack++);        \
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                STAT(tcpstat.tcps_rcvbyte += (ti)->ti_len);  \
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                if (so->so_emu) { \
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                        if (tcp_emu((so),(m))) sbappend(so, (m)); \
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                } else \
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                        sbappend((so), (m)); \
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/*                sorwakeup(so); */ \
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        } else { \
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                (flags) = tcp_reass((tp), (ti), (m)); \
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                tp->t_flags |= TF_ACKNOW; \
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        } \
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}
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#endif
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static void tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt,
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                          struct tcpiphdr *ti);
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static void tcp_xmit_timer(register struct tcpcb *tp, int rtt);
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static int
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tcp_reass(register struct tcpcb *tp, register struct tcpiphdr *ti,
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          struct mbuf *m)
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{
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        register struct tcpiphdr *q;
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        struct socket *so = tp->t_socket;
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        int flags;
122 5fafdf24 ths
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        /*
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         * Call with ti==NULL after become established to
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         * force pre-ESTABLISHED data up to user socket.
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         */
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        if (ti == NULL)
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                goto present;
129 f0cbd3ec bellard
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        /*
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         * Find a segment which begins after this one does.
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         */
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        for (q = tcpfrag_list_first(tp); !tcpfrag_list_end(q, tp);
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            q = tcpiphdr_next(q))
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                if (SEQ_GT(q->ti_seq, ti->ti_seq))
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                        break;
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        /*
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         * If there is a preceding segment, it may provide some of
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         * our data already.  If so, drop the data from the incoming
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         * segment.  If it provides all of our data, drop us.
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         */
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        if (!tcpfrag_list_end(tcpiphdr_prev(q), tp)) {
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                register int i;
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                q = tcpiphdr_prev(q);
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                /* conversion to int (in i) handles seq wraparound */
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                i = q->ti_seq + q->ti_len - ti->ti_seq;
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                if (i > 0) {
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                        if (i >= ti->ti_len) {
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                                STAT(tcpstat.tcps_rcvduppack++);
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                                STAT(tcpstat.tcps_rcvdupbyte += ti->ti_len);
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                                m_freem(m);
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                                /*
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                                 * Try to present any queued data
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                                 * at the left window edge to the user.
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                                 * This is needed after the 3-WHS
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                                 * completes.
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                                 */
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                                goto present;   /* ??? */
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                        }
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                        m_adj(m, i);
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                        ti->ti_len -= i;
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                        ti->ti_seq += i;
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                }
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                q = tcpiphdr_next(q);
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        }
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        STAT(tcpstat.tcps_rcvoopack++);
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        STAT(tcpstat.tcps_rcvoobyte += ti->ti_len);
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        ti->ti_mbuf = m;
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        /*
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         * While we overlap succeeding segments trim them or,
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         * if they are completely covered, dequeue them.
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         */
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        while (!tcpfrag_list_end(q, tp)) {
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                register int i = (ti->ti_seq + ti->ti_len) - q->ti_seq;
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                if (i <= 0)
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                        break;
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                if (i < q->ti_len) {
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                        q->ti_seq += i;
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                        q->ti_len -= i;
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                        m_adj(q->ti_mbuf, i);
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                        break;
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                }
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                q = tcpiphdr_next(q);
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                m = tcpiphdr_prev(q)->ti_mbuf;
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                remque(tcpiphdr2qlink(tcpiphdr_prev(q)));
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                m_freem(m);
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        }
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        /*
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         * Stick new segment in its place.
193 f0cbd3ec bellard
         */
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        insque(tcpiphdr2qlink(ti), tcpiphdr2qlink(tcpiphdr_prev(q)));
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present:
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        /*
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         * Present data to user, advancing rcv_nxt through
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         * completed sequence space.
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         */
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        if (!TCPS_HAVEESTABLISHED(tp->t_state))
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                return (0);
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        ti = tcpfrag_list_first(tp);
204 429d0a3d blueswir1
        if (tcpfrag_list_end(ti, tp) || ti->ti_seq != tp->rcv_nxt)
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                return (0);
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        if (tp->t_state == TCPS_SYN_RECEIVED && ti->ti_len)
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                return (0);
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        do {
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                tp->rcv_nxt += ti->ti_len;
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                flags = ti->ti_flags & TH_FIN;
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                remque(tcpiphdr2qlink(ti));
212 429d0a3d blueswir1
                m = ti->ti_mbuf;
213 429d0a3d blueswir1
                ti = tcpiphdr_next(ti);
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/*                if (so->so_state & SS_FCANTRCVMORE) */
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                if (so->so_state & SS_FCANTSENDMORE)
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                        m_freem(m);
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                else {
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                        if (so->so_emu) {
219 f0cbd3ec bellard
                                if (tcp_emu(so,m)) sbappend(so, m);
220 f0cbd3ec bellard
                        } else
221 f0cbd3ec bellard
                                sbappend(so, m);
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                }
223 f0cbd3ec bellard
        } while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt);
224 f0cbd3ec bellard
/*        sorwakeup(so); */
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        return (flags);
226 f0cbd3ec bellard
}
227 f0cbd3ec bellard
228 f0cbd3ec bellard
/*
229 f0cbd3ec bellard
 * TCP input routine, follows pages 65-76 of the
230 f0cbd3ec bellard
 * protocol specification dated September, 1981 very closely.
231 f0cbd3ec bellard
 */
232 f0cbd3ec bellard
void
233 511d2b14 blueswir1
tcp_input(struct mbuf *m, int iphlen, struct socket *inso)
234 f0cbd3ec bellard
{
235 f0cbd3ec bellard
          struct ip save_ip, *ip;
236 f0cbd3ec bellard
        register struct tcpiphdr *ti;
237 f0cbd3ec bellard
        caddr_t optp = NULL;
238 f0cbd3ec bellard
        int optlen = 0;
239 f0cbd3ec bellard
        int len, tlen, off;
240 511d2b14 blueswir1
        register struct tcpcb *tp = NULL;
241 f0cbd3ec bellard
        register int tiflags;
242 511d2b14 blueswir1
        struct socket *so = NULL;
243 f0cbd3ec bellard
        int todrop, acked, ourfinisacked, needoutput = 0;
244 f0cbd3ec bellard
/*        int dropsocket = 0; */
245 f0cbd3ec bellard
        int iss = 0;
246 f0cbd3ec bellard
        u_long tiwin;
247 f0cbd3ec bellard
        int ret;
248 f0cbd3ec bellard
/*        int ts_present = 0; */
249 a9ba3a85 aliguori
    struct ex_list *ex_ptr;
250 f0cbd3ec bellard
251 f0cbd3ec bellard
        DEBUG_CALL("tcp_input");
252 5fafdf24 ths
        DEBUG_ARGS((dfd," m = %8lx  iphlen = %2d  inso = %lx\n",
253 f0cbd3ec bellard
                    (long )m, iphlen, (long )inso ));
254 5fafdf24 ths
255 f0cbd3ec bellard
        /*
256 f0cbd3ec bellard
         * If called with m == 0, then we're continuing the connect
257 f0cbd3ec bellard
         */
258 f0cbd3ec bellard
        if (m == NULL) {
259 f0cbd3ec bellard
                so = inso;
260 3b46e624 ths
261 f0cbd3ec bellard
                /* Re-set a few variables */
262 f0cbd3ec bellard
                tp = sototcpcb(so);
263 f0cbd3ec bellard
                m = so->so_m;
264 511d2b14 blueswir1
                so->so_m = NULL;
265 f0cbd3ec bellard
                ti = so->so_ti;
266 f0cbd3ec bellard
                tiwin = ti->ti_win;
267 f0cbd3ec bellard
                tiflags = ti->ti_flags;
268 3b46e624 ths
269 f0cbd3ec bellard
                goto cont_conn;
270 f0cbd3ec bellard
        }
271 5fafdf24 ths
272 5fafdf24 ths
273 31a60e22 blueswir1
        STAT(tcpstat.tcps_rcvtotal++);
274 f0cbd3ec bellard
        /*
275 f0cbd3ec bellard
         * Get IP and TCP header together in first mbuf.
276 f0cbd3ec bellard
         * Note: IP leaves IP header in first mbuf.
277 f0cbd3ec bellard
         */
278 f0cbd3ec bellard
        ti = mtod(m, struct tcpiphdr *);
279 f0cbd3ec bellard
        if (iphlen > sizeof(struct ip )) {
280 f0cbd3ec bellard
          ip_stripoptions(m, (struct mbuf *)0);
281 f0cbd3ec bellard
          iphlen=sizeof(struct ip );
282 f0cbd3ec bellard
        }
283 f0cbd3ec bellard
        /* XXX Check if too short */
284 5fafdf24 ths
285 f0cbd3ec bellard
286 f0cbd3ec bellard
        /*
287 f0cbd3ec bellard
         * Save a copy of the IP header in case we want restore it
288 f0cbd3ec bellard
         * for sending an ICMP error message in response.
289 f0cbd3ec bellard
         */
290 f0cbd3ec bellard
        ip=mtod(m, struct ip *);
291 5fafdf24 ths
        save_ip = *ip;
292 f0cbd3ec bellard
        save_ip.ip_len+= iphlen;
293 f0cbd3ec bellard
294 f0cbd3ec bellard
        /*
295 f0cbd3ec bellard
         * Checksum extended TCP header and data.
296 f0cbd3ec bellard
         */
297 f0cbd3ec bellard
        tlen = ((struct ip *)ti)->ip_len;
298 511d2b14 blueswir1
        tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL;
299 511d2b14 blueswir1
        memset(&ti->ti_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr));
300 f0cbd3ec bellard
        ti->ti_x1 = 0;
301 f0cbd3ec bellard
        ti->ti_len = htons((u_int16_t)tlen);
302 f0cbd3ec bellard
        len = sizeof(struct ip ) + tlen;
303 f0cbd3ec bellard
        /* keep checksum for ICMP reply
304 5fafdf24 ths
         * ti->ti_sum = cksum(m, len);
305 f0cbd3ec bellard
         * if (ti->ti_sum) { */
306 f0cbd3ec bellard
        if(cksum(m, len)) {
307 31a60e22 blueswir1
          STAT(tcpstat.tcps_rcvbadsum++);
308 f0cbd3ec bellard
          goto drop;
309 f0cbd3ec bellard
        }
310 f0cbd3ec bellard
311 f0cbd3ec bellard
        /*
312 f0cbd3ec bellard
         * Check that TCP offset makes sense,
313 f0cbd3ec bellard
         * pull out TCP options and adjust length.                XXX
314 f0cbd3ec bellard
         */
315 f0cbd3ec bellard
        off = ti->ti_off << 2;
316 f0cbd3ec bellard
        if (off < sizeof (struct tcphdr) || off > tlen) {
317 31a60e22 blueswir1
          STAT(tcpstat.tcps_rcvbadoff++);
318 f0cbd3ec bellard
          goto drop;
319 f0cbd3ec bellard
        }
320 f0cbd3ec bellard
        tlen -= off;
321 f0cbd3ec bellard
        ti->ti_len = tlen;
322 f0cbd3ec bellard
        if (off > sizeof (struct tcphdr)) {
323 f0cbd3ec bellard
          optlen = off - sizeof (struct tcphdr);
324 f0cbd3ec bellard
          optp = mtod(m, caddr_t) + sizeof (struct tcpiphdr);
325 f0cbd3ec bellard
326 5fafdf24 ths
                /*
327 f0cbd3ec bellard
                 * Do quick retrieval of timestamp options ("options
328 f0cbd3ec bellard
                 * prediction?").  If timestamp is the only option and it's
329 f0cbd3ec bellard
                 * formatted as recommended in RFC 1323 appendix A, we
330 f0cbd3ec bellard
                 * quickly get the values now and not bother calling
331 f0cbd3ec bellard
                 * tcp_dooptions(), etc.
332 f0cbd3ec bellard
                 */
333 f0cbd3ec bellard
/*                if ((optlen == TCPOLEN_TSTAMP_APPA ||
334 f0cbd3ec bellard
 *                     (optlen > TCPOLEN_TSTAMP_APPA &&
335 f0cbd3ec bellard
 *                        optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) &&
336 f0cbd3ec bellard
 *                     *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) &&
337 f0cbd3ec bellard
 *                     (ti->ti_flags & TH_SYN) == 0) {
338 f0cbd3ec bellard
 *                        ts_present = 1;
339 f0cbd3ec bellard
 *                        ts_val = ntohl(*(u_int32_t *)(optp + 4));
340 f0cbd3ec bellard
 *                        ts_ecr = ntohl(*(u_int32_t *)(optp + 8));
341 f0cbd3ec bellard
 *                        optp = NULL;   / * we've parsed the options * /
342 f0cbd3ec bellard
 *                }
343 f0cbd3ec bellard
 */
344 f0cbd3ec bellard
        }
345 f0cbd3ec bellard
        tiflags = ti->ti_flags;
346 5fafdf24 ths
347 f0cbd3ec bellard
        /*
348 f0cbd3ec bellard
         * Convert TCP protocol specific fields to host format.
349 f0cbd3ec bellard
         */
350 f0cbd3ec bellard
        NTOHL(ti->ti_seq);
351 f0cbd3ec bellard
        NTOHL(ti->ti_ack);
352 f0cbd3ec bellard
        NTOHS(ti->ti_win);
353 f0cbd3ec bellard
        NTOHS(ti->ti_urp);
354 f0cbd3ec bellard
355 f0cbd3ec bellard
        /*
356 f0cbd3ec bellard
         * Drop TCP, IP headers and TCP options.
357 f0cbd3ec bellard
         */
358 f0cbd3ec bellard
        m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
359 f0cbd3ec bellard
        m->m_len  -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
360 5fafdf24 ths
361 a9ba3a85 aliguori
    if (slirp_restrict) {
362 a9ba3a85 aliguori
        for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
363 a9ba3a85 aliguori
            if (ex_ptr->ex_fport == ti->ti_dport &&
364 a9ba3a85 aliguori
                    (ntohl(ti->ti_dst.s_addr) & 0xff) == ex_ptr->ex_addr)
365 a9ba3a85 aliguori
                break;
366 a9ba3a85 aliguori
367 a9ba3a85 aliguori
        if (!ex_ptr)
368 a9ba3a85 aliguori
            goto drop;
369 a9ba3a85 aliguori
    }
370 f0cbd3ec bellard
        /*
371 f0cbd3ec bellard
         * Locate pcb for segment.
372 f0cbd3ec bellard
         */
373 f0cbd3ec bellard
findso:
374 f0cbd3ec bellard
        so = tcp_last_so;
375 f0cbd3ec bellard
        if (so->so_fport != ti->ti_dport ||
376 f0cbd3ec bellard
            so->so_lport != ti->ti_sport ||
377 f0cbd3ec bellard
            so->so_laddr.s_addr != ti->ti_src.s_addr ||
378 f0cbd3ec bellard
            so->so_faddr.s_addr != ti->ti_dst.s_addr) {
379 f0cbd3ec bellard
                so = solookup(&tcb, ti->ti_src, ti->ti_sport,
380 f0cbd3ec bellard
                               ti->ti_dst, ti->ti_dport);
381 f0cbd3ec bellard
                if (so)
382 f0cbd3ec bellard
                        tcp_last_so = so;
383 31a60e22 blueswir1
                STAT(tcpstat.tcps_socachemiss++);
384 f0cbd3ec bellard
        }
385 f0cbd3ec bellard
386 f0cbd3ec bellard
        /*
387 f0cbd3ec bellard
         * If the state is CLOSED (i.e., TCB does not exist) then
388 f0cbd3ec bellard
         * all data in the incoming segment is discarded.
389 f0cbd3ec bellard
         * If the TCB exists but is in CLOSED state, it is embryonic,
390 f0cbd3ec bellard
         * but should either do a listen or a connect soon.
391 f0cbd3ec bellard
         *
392 f0cbd3ec bellard
         * state == CLOSED means we've done socreate() but haven't
393 5fafdf24 ths
         * attached it to a protocol yet...
394 5fafdf24 ths
         *
395 f0cbd3ec bellard
         * XXX If a TCB does not exist, and the TH_SYN flag is
396 f0cbd3ec bellard
         * the only flag set, then create a session, mark it
397 f0cbd3ec bellard
         * as if it was LISTENING, and continue...
398 f0cbd3ec bellard
         */
399 511d2b14 blueswir1
        if (so == NULL) {
400 f0cbd3ec bellard
          if ((tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) != TH_SYN)
401 f0cbd3ec bellard
            goto dropwithreset;
402 3b46e624 ths
403 f0cbd3ec bellard
          if ((so = socreate()) == NULL)
404 f0cbd3ec bellard
            goto dropwithreset;
405 f0cbd3ec bellard
          if (tcp_attach(so) < 0) {
406 f0cbd3ec bellard
            free(so); /* Not sofree (if it failed, it's not insqued) */
407 f0cbd3ec bellard
            goto dropwithreset;
408 f0cbd3ec bellard
          }
409 3b46e624 ths
410 9634d903 blueswir1
          sbreserve(&so->so_snd, TCP_SNDSPACE);
411 9634d903 blueswir1
          sbreserve(&so->so_rcv, TCP_RCVSPACE);
412 3b46e624 ths
413 f0cbd3ec bellard
          /*                tcp_last_so = so; */  /* XXX ? */
414 f0cbd3ec bellard
          /*                tp = sototcpcb(so);    */
415 3b46e624 ths
416 f0cbd3ec bellard
          so->so_laddr = ti->ti_src;
417 f0cbd3ec bellard
          so->so_lport = ti->ti_sport;
418 f0cbd3ec bellard
          so->so_faddr = ti->ti_dst;
419 f0cbd3ec bellard
          so->so_fport = ti->ti_dport;
420 3b46e624 ths
421 f0cbd3ec bellard
          if ((so->so_iptos = tcp_tos(so)) == 0)
422 f0cbd3ec bellard
            so->so_iptos = ((struct ip *)ti)->ip_tos;
423 3b46e624 ths
424 f0cbd3ec bellard
          tp = sototcpcb(so);
425 f0cbd3ec bellard
          tp->t_state = TCPS_LISTEN;
426 f0cbd3ec bellard
        }
427 3b46e624 ths
428 f0cbd3ec bellard
        /*
429 f0cbd3ec bellard
         * If this is a still-connecting socket, this probably
430 f0cbd3ec bellard
         * a retransmit of the SYN.  Whether it's a retransmit SYN
431 f0cbd3ec bellard
         * or something else, we nuke it.
432 f0cbd3ec bellard
         */
433 f0cbd3ec bellard
        if (so->so_state & SS_ISFCONNECTING)
434 f0cbd3ec bellard
                goto drop;
435 f0cbd3ec bellard
436 f0cbd3ec bellard
        tp = sototcpcb(so);
437 5fafdf24 ths
438 f0cbd3ec bellard
        /* XXX Should never fail */
439 511d2b14 blueswir1
        if (tp == NULL)
440 f0cbd3ec bellard
                goto dropwithreset;
441 f0cbd3ec bellard
        if (tp->t_state == TCPS_CLOSED)
442 f0cbd3ec bellard
                goto drop;
443 5fafdf24 ths
444 f0cbd3ec bellard
        /* Unscale the window into a 32-bit value. */
445 f0cbd3ec bellard
/*        if ((tiflags & TH_SYN) == 0)
446 f0cbd3ec bellard
 *                tiwin = ti->ti_win << tp->snd_scale;
447 f0cbd3ec bellard
 *        else
448 f0cbd3ec bellard
 */
449 f0cbd3ec bellard
                tiwin = ti->ti_win;
450 f0cbd3ec bellard
451 f0cbd3ec bellard
        /*
452 f0cbd3ec bellard
         * Segment received on connection.
453 f0cbd3ec bellard
         * Reset idle time and keep-alive timer.
454 f0cbd3ec bellard
         */
455 f0cbd3ec bellard
        tp->t_idle = 0;
456 9634d903 blueswir1
        if (SO_OPTIONS)
457 9634d903 blueswir1
           tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL;
458 f0cbd3ec bellard
        else
459 9634d903 blueswir1
           tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE;
460 f0cbd3ec bellard
461 f0cbd3ec bellard
        /*
462 f0cbd3ec bellard
         * Process options if not in LISTEN state,
463 f0cbd3ec bellard
         * else do it below (after getting remote address).
464 f0cbd3ec bellard
         */
465 f0cbd3ec bellard
        if (optp && tp->t_state != TCPS_LISTEN)
466 5fafdf24 ths
                tcp_dooptions(tp, (u_char *)optp, optlen, ti);
467 f0cbd3ec bellard
/* , */
468 f0cbd3ec bellard
/*                        &ts_present, &ts_val, &ts_ecr); */
469 f0cbd3ec bellard
470 5fafdf24 ths
        /*
471 f0cbd3ec bellard
         * Header prediction: check for the two common cases
472 f0cbd3ec bellard
         * of a uni-directional data xfer.  If the packet has
473 f0cbd3ec bellard
         * no control flags, is in-sequence, the window didn't
474 f0cbd3ec bellard
         * change and we're not retransmitting, it's a
475 f0cbd3ec bellard
         * candidate.  If the length is zero and the ack moved
476 f0cbd3ec bellard
         * forward, we're the sender side of the xfer.  Just
477 f0cbd3ec bellard
         * free the data acked & wake any higher level process
478 f0cbd3ec bellard
         * that was blocked waiting for space.  If the length
479 f0cbd3ec bellard
         * is non-zero and the ack didn't move, we're the
480 f0cbd3ec bellard
         * receiver side.  If we're getting packets in-order
481 f0cbd3ec bellard
         * (the reassembly queue is empty), add the data to
482 f0cbd3ec bellard
         * the socket buffer and note that we need a delayed ack.
483 f0cbd3ec bellard
         *
484 f0cbd3ec bellard
         * XXX Some of these tests are not needed
485 f0cbd3ec bellard
         * eg: the tiwin == tp->snd_wnd prevents many more
486 f0cbd3ec bellard
         * predictions.. with no *real* advantage..
487 f0cbd3ec bellard
         */
488 f0cbd3ec bellard
        if (tp->t_state == TCPS_ESTABLISHED &&
489 f0cbd3ec bellard
            (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
490 f0cbd3ec bellard
/*            (!ts_present || TSTMP_GEQ(ts_val, tp->ts_recent)) && */
491 f0cbd3ec bellard
            ti->ti_seq == tp->rcv_nxt &&
492 f0cbd3ec bellard
            tiwin && tiwin == tp->snd_wnd &&
493 f0cbd3ec bellard
            tp->snd_nxt == tp->snd_max) {
494 5fafdf24 ths
                /*
495 f0cbd3ec bellard
                 * If last ACK falls within this segment's sequence numbers,
496 f0cbd3ec bellard
                 *  record the timestamp.
497 f0cbd3ec bellard
                 */
498 f0cbd3ec bellard
/*                if (ts_present && SEQ_LEQ(ti->ti_seq, tp->last_ack_sent) &&
499 f0cbd3ec bellard
 *                   SEQ_LT(tp->last_ack_sent, ti->ti_seq + ti->ti_len)) {
500 f0cbd3ec bellard
 *                        tp->ts_recent_age = tcp_now;
501 f0cbd3ec bellard
 *                        tp->ts_recent = ts_val;
502 f0cbd3ec bellard
 *                }
503 f0cbd3ec bellard
 */
504 f0cbd3ec bellard
                if (ti->ti_len == 0) {
505 f0cbd3ec bellard
                        if (SEQ_GT(ti->ti_ack, tp->snd_una) &&
506 f0cbd3ec bellard
                            SEQ_LEQ(ti->ti_ack, tp->snd_max) &&
507 f0cbd3ec bellard
                            tp->snd_cwnd >= tp->snd_wnd) {
508 f0cbd3ec bellard
                                /*
509 f0cbd3ec bellard
                                 * this is a pure ack for outstanding data.
510 f0cbd3ec bellard
                                 */
511 31a60e22 blueswir1
                                STAT(tcpstat.tcps_predack++);
512 f0cbd3ec bellard
/*                                if (ts_present)
513 f0cbd3ec bellard
 *                                        tcp_xmit_timer(tp, tcp_now-ts_ecr+1);
514 5fafdf24 ths
 *                                else
515 f0cbd3ec bellard
 */                                     if (tp->t_rtt &&
516 f0cbd3ec bellard
                                            SEQ_GT(ti->ti_ack, tp->t_rtseq))
517 f0cbd3ec bellard
                                        tcp_xmit_timer(tp, tp->t_rtt);
518 f0cbd3ec bellard
                                acked = ti->ti_ack - tp->snd_una;
519 31a60e22 blueswir1
                                STAT(tcpstat.tcps_rcvackpack++);
520 31a60e22 blueswir1
                                STAT(tcpstat.tcps_rcvackbyte += acked);
521 f0cbd3ec bellard
                                sbdrop(&so->so_snd, acked);
522 f0cbd3ec bellard
                                tp->snd_una = ti->ti_ack;
523 f0cbd3ec bellard
                                m_freem(m);
524 f0cbd3ec bellard
525 f0cbd3ec bellard
                                /*
526 f0cbd3ec bellard
                                 * If all outstanding data are acked, stop
527 f0cbd3ec bellard
                                 * retransmit timer, otherwise restart timer
528 f0cbd3ec bellard
                                 * using current (possibly backed-off) value.
529 f0cbd3ec bellard
                                 * If process is waiting for space,
530 f0cbd3ec bellard
                                 * wakeup/selwakeup/signal.  If data
531 f0cbd3ec bellard
                                 * are ready to send, let tcp_output
532 f0cbd3ec bellard
                                 * decide between more output or persist.
533 f0cbd3ec bellard
                                 */
534 f0cbd3ec bellard
                                if (tp->snd_una == tp->snd_max)
535 f0cbd3ec bellard
                                        tp->t_timer[TCPT_REXMT] = 0;
536 f0cbd3ec bellard
                                else if (tp->t_timer[TCPT_PERSIST] == 0)
537 f0cbd3ec bellard
                                        tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
538 f0cbd3ec bellard
539 5fafdf24 ths
                                /*
540 f0cbd3ec bellard
                                 * There's room in so_snd, sowwakup will read()
541 f0cbd3ec bellard
                                 * from the socket if we can
542 f0cbd3ec bellard
                                 */
543 f0cbd3ec bellard
/*                                if (so->so_snd.sb_flags & SB_NOTIFY)
544 f0cbd3ec bellard
 *                                        sowwakeup(so);
545 f0cbd3ec bellard
 */
546 5fafdf24 ths
                                /*
547 f0cbd3ec bellard
                                 * This is called because sowwakeup might have
548 f0cbd3ec bellard
                                 * put data into so_snd.  Since we don't so sowwakeup,
549 f0cbd3ec bellard
                                 * we don't need this.. XXX???
550 f0cbd3ec bellard
                                 */
551 f0cbd3ec bellard
                                if (so->so_snd.sb_cc)
552 f0cbd3ec bellard
                                        (void) tcp_output(tp);
553 f0cbd3ec bellard
554 f0cbd3ec bellard
                                return;
555 f0cbd3ec bellard
                        }
556 f0cbd3ec bellard
                } else if (ti->ti_ack == tp->snd_una &&
557 429d0a3d blueswir1
                    tcpfrag_list_empty(tp) &&
558 f0cbd3ec bellard
                    ti->ti_len <= sbspace(&so->so_rcv)) {
559 f0cbd3ec bellard
                        /*
560 f0cbd3ec bellard
                         * this is a pure, in-sequence data packet
561 f0cbd3ec bellard
                         * with nothing on the reassembly queue and
562 f0cbd3ec bellard
                         * we have enough buffer space to take it.
563 f0cbd3ec bellard
                         */
564 31a60e22 blueswir1
                        STAT(tcpstat.tcps_preddat++);
565 f0cbd3ec bellard
                        tp->rcv_nxt += ti->ti_len;
566 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvpack++);
567 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvbyte += ti->ti_len);
568 f0cbd3ec bellard
                        /*
569 f0cbd3ec bellard
                         * Add data to socket buffer.
570 f0cbd3ec bellard
                         */
571 f0cbd3ec bellard
                        if (so->so_emu) {
572 f0cbd3ec bellard
                                if (tcp_emu(so,m)) sbappend(so, m);
573 f0cbd3ec bellard
                        } else
574 f0cbd3ec bellard
                                sbappend(so, m);
575 3b46e624 ths
576 5fafdf24 ths
                        /*
577 f0cbd3ec bellard
                         * XXX This is called when data arrives.  Later, check
578 f0cbd3ec bellard
                         * if we can actually write() to the socket
579 f0cbd3ec bellard
                         * XXX Need to check? It's be NON_BLOCKING
580 f0cbd3ec bellard
                         */
581 f0cbd3ec bellard
/*                        sorwakeup(so); */
582 3b46e624 ths
583 f0cbd3ec bellard
                        /*
584 f0cbd3ec bellard
                         * If this is a short packet, then ACK now - with Nagel
585 f0cbd3ec bellard
                         *        congestion avoidance sender won't send more until
586 f0cbd3ec bellard
                         *        he gets an ACK.
587 5fafdf24 ths
                         *
588 4f552e3b bellard
                         * It is better to not delay acks at all to maximize
589 4f552e3b bellard
                         * TCP throughput.  See RFC 2581.
590 5fafdf24 ths
                         */
591 4f552e3b bellard
                        tp->t_flags |= TF_ACKNOW;
592 4f552e3b bellard
                        tcp_output(tp);
593 f0cbd3ec bellard
                        return;
594 f0cbd3ec bellard
                }
595 f0cbd3ec bellard
        } /* header prediction */
596 f0cbd3ec bellard
        /*
597 f0cbd3ec bellard
         * Calculate amount of space in receive window,
598 f0cbd3ec bellard
         * and then do TCP input processing.
599 f0cbd3ec bellard
         * Receive window is amount of space in rcv queue,
600 f0cbd3ec bellard
         * but not less than advertised window.
601 f0cbd3ec bellard
         */
602 f0cbd3ec bellard
        { int win;
603 f0cbd3ec bellard
          win = sbspace(&so->so_rcv);
604 f0cbd3ec bellard
          if (win < 0)
605 f0cbd3ec bellard
            win = 0;
606 f0cbd3ec bellard
          tp->rcv_wnd = max(win, (int)(tp->rcv_adv - tp->rcv_nxt));
607 f0cbd3ec bellard
        }
608 f0cbd3ec bellard
609 f0cbd3ec bellard
        switch (tp->t_state) {
610 f0cbd3ec bellard
611 f0cbd3ec bellard
        /*
612 f0cbd3ec bellard
         * If the state is LISTEN then ignore segment if it contains an RST.
613 f0cbd3ec bellard
         * If the segment contains an ACK then it is bad and send a RST.
614 f0cbd3ec bellard
         * If it does not contain a SYN then it is not interesting; drop it.
615 f0cbd3ec bellard
         * Don't bother responding if the destination was a broadcast.
616 f0cbd3ec bellard
         * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial
617 f0cbd3ec bellard
         * tp->iss, and send a segment:
618 f0cbd3ec bellard
         *     <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
619 f0cbd3ec bellard
         * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss.
620 f0cbd3ec bellard
         * Fill in remote peer address fields if not previously specified.
621 f0cbd3ec bellard
         * Enter SYN_RECEIVED state, and process any other fields of this
622 f0cbd3ec bellard
         * segment in this state.
623 f0cbd3ec bellard
         */
624 f0cbd3ec bellard
        case TCPS_LISTEN: {
625 f0cbd3ec bellard
626 f0cbd3ec bellard
          if (tiflags & TH_RST)
627 f0cbd3ec bellard
            goto drop;
628 f0cbd3ec bellard
          if (tiflags & TH_ACK)
629 f0cbd3ec bellard
            goto dropwithreset;
630 f0cbd3ec bellard
          if ((tiflags & TH_SYN) == 0)
631 f0cbd3ec bellard
            goto drop;
632 3b46e624 ths
633 f0cbd3ec bellard
          /*
634 f0cbd3ec bellard
           * This has way too many gotos...
635 f0cbd3ec bellard
           * But a bit of spaghetti code never hurt anybody :)
636 f0cbd3ec bellard
           */
637 3b46e624 ths
638 f0cbd3ec bellard
          /*
639 f0cbd3ec bellard
           * If this is destined for the control address, then flag to
640 f0cbd3ec bellard
           * tcp_ctl once connected, otherwise connect
641 f0cbd3ec bellard
           */
642 f0cbd3ec bellard
          if ((so->so_faddr.s_addr&htonl(0xffffff00)) == special_addr.s_addr) {
643 f0cbd3ec bellard
            int lastbyte=ntohl(so->so_faddr.s_addr) & 0xff;
644 f0cbd3ec bellard
            if (lastbyte!=CTL_ALIAS && lastbyte!=CTL_DNS) {
645 f0cbd3ec bellard
#if 0
646 f0cbd3ec bellard
              if(lastbyte==CTL_CMD || lastbyte==CTL_EXEC) {
647 f0cbd3ec bellard
                /* Command or exec adress */
648 f0cbd3ec bellard
                so->so_state |= SS_CTL;
649 5fafdf24 ths
              } else
650 a3d4af03 bellard
#endif
651 a3d4af03 bellard
              {
652 f0cbd3ec bellard
                /* May be an add exec */
653 f0cbd3ec bellard
                for(ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
654 5fafdf24 ths
                  if(ex_ptr->ex_fport == so->so_fport &&
655 f0cbd3ec bellard
                     lastbyte == ex_ptr->ex_addr) {
656 f0cbd3ec bellard
                    so->so_state |= SS_CTL;
657 f0cbd3ec bellard
                    break;
658 f0cbd3ec bellard
                  }
659 f0cbd3ec bellard
                }
660 f0cbd3ec bellard
              }
661 f0cbd3ec bellard
              if(so->so_state & SS_CTL) goto cont_input;
662 f0cbd3ec bellard
            }
663 f0cbd3ec bellard
            /* CTL_ALIAS: Do nothing, tcp_fconnect will be called on it */
664 f0cbd3ec bellard
          }
665 3b46e624 ths
666 f0cbd3ec bellard
          if (so->so_emu & EMU_NOCONNECT) {
667 f0cbd3ec bellard
            so->so_emu &= ~EMU_NOCONNECT;
668 f0cbd3ec bellard
            goto cont_input;
669 f0cbd3ec bellard
          }
670 3b46e624 ths
671 02d2c54c bellard
          if((tcp_fconnect(so) == -1) && (errno != EINPROGRESS) && (errno != EWOULDBLOCK)) {
672 f0cbd3ec bellard
            u_char code=ICMP_UNREACH_NET;
673 f0cbd3ec bellard
            DEBUG_MISC((dfd," tcp fconnect errno = %d-%s\n",
674 f0cbd3ec bellard
                        errno,strerror(errno)));
675 f0cbd3ec bellard
            if(errno == ECONNREFUSED) {
676 f0cbd3ec bellard
              /* ACK the SYN, send RST to refuse the connection */
677 f0cbd3ec bellard
              tcp_respond(tp, ti, m, ti->ti_seq+1, (tcp_seq)0,
678 5fafdf24 ths
                          TH_RST|TH_ACK);
679 f0cbd3ec bellard
            } else {
680 f0cbd3ec bellard
              if(errno == EHOSTUNREACH) code=ICMP_UNREACH_HOST;
681 f0cbd3ec bellard
              HTONL(ti->ti_seq);             /* restore tcp header */
682 f0cbd3ec bellard
              HTONL(ti->ti_ack);
683 f0cbd3ec bellard
              HTONS(ti->ti_win);
684 f0cbd3ec bellard
              HTONS(ti->ti_urp);
685 f0cbd3ec bellard
              m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
686 f0cbd3ec bellard
              m->m_len  += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr);
687 f0cbd3ec bellard
              *ip=save_ip;
688 f0cbd3ec bellard
              icmp_error(m, ICMP_UNREACH,code, 0,strerror(errno));
689 f0cbd3ec bellard
            }
690 f0cbd3ec bellard
            tp = tcp_close(tp);
691 f0cbd3ec bellard
            m_free(m);
692 f0cbd3ec bellard
          } else {
693 f0cbd3ec bellard
            /*
694 f0cbd3ec bellard
             * Haven't connected yet, save the current mbuf
695 f0cbd3ec bellard
             * and ti, and return
696 f0cbd3ec bellard
             * XXX Some OS's don't tell us whether the connect()
697 f0cbd3ec bellard
             * succeeded or not.  So we must time it out.
698 f0cbd3ec bellard
             */
699 f0cbd3ec bellard
            so->so_m = m;
700 f0cbd3ec bellard
            so->so_ti = ti;
701 f0cbd3ec bellard
            tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
702 f0cbd3ec bellard
            tp->t_state = TCPS_SYN_RECEIVED;
703 f0cbd3ec bellard
          }
704 f0cbd3ec bellard
          return;
705 f0cbd3ec bellard
706 3b46e624 ths
        cont_conn:
707 5fafdf24 ths
          /* m==NULL
708 f0cbd3ec bellard
           * Check if the connect succeeded
709 f0cbd3ec bellard
           */
710 f0cbd3ec bellard
          if (so->so_state & SS_NOFDREF) {
711 f0cbd3ec bellard
            tp = tcp_close(tp);
712 f0cbd3ec bellard
            goto dropwithreset;
713 f0cbd3ec bellard
          }
714 3b46e624 ths
        cont_input:
715 f0cbd3ec bellard
          tcp_template(tp);
716 3b46e624 ths
717 f0cbd3ec bellard
          if (optp)
718 f0cbd3ec bellard
            tcp_dooptions(tp, (u_char *)optp, optlen, ti);
719 f0cbd3ec bellard
          /* , */
720 f0cbd3ec bellard
          /*                                &ts_present, &ts_val, &ts_ecr); */
721 3b46e624 ths
722 f0cbd3ec bellard
          if (iss)
723 f0cbd3ec bellard
            tp->iss = iss;
724 5fafdf24 ths
          else
725 f0cbd3ec bellard
            tp->iss = tcp_iss;
726 f0cbd3ec bellard
          tcp_iss += TCP_ISSINCR/2;
727 f0cbd3ec bellard
          tp->irs = ti->ti_seq;
728 f0cbd3ec bellard
          tcp_sendseqinit(tp);
729 f0cbd3ec bellard
          tcp_rcvseqinit(tp);
730 f0cbd3ec bellard
          tp->t_flags |= TF_ACKNOW;
731 f0cbd3ec bellard
          tp->t_state = TCPS_SYN_RECEIVED;
732 f0cbd3ec bellard
          tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
733 31a60e22 blueswir1
          STAT(tcpstat.tcps_accepts++);
734 f0cbd3ec bellard
          goto trimthenstep6;
735 f0cbd3ec bellard
        } /* case TCPS_LISTEN */
736 5fafdf24 ths
737 f0cbd3ec bellard
        /*
738 f0cbd3ec bellard
         * If the state is SYN_SENT:
739 f0cbd3ec bellard
         *        if seg contains an ACK, but not for our SYN, drop the input.
740 f0cbd3ec bellard
         *        if seg contains a RST, then drop the connection.
741 f0cbd3ec bellard
         *        if seg does not contain SYN, then drop it.
742 f0cbd3ec bellard
         * Otherwise this is an acceptable SYN segment
743 f0cbd3ec bellard
         *        initialize tp->rcv_nxt and tp->irs
744 f0cbd3ec bellard
         *        if seg contains ack then advance tp->snd_una
745 f0cbd3ec bellard
         *        if SYN has been acked change to ESTABLISHED else SYN_RCVD state
746 f0cbd3ec bellard
         *        arrange for segment to be acked (eventually)
747 f0cbd3ec bellard
         *        continue processing rest of data/controls, beginning with URG
748 f0cbd3ec bellard
         */
749 f0cbd3ec bellard
        case TCPS_SYN_SENT:
750 f0cbd3ec bellard
                if ((tiflags & TH_ACK) &&
751 f0cbd3ec bellard
                    (SEQ_LEQ(ti->ti_ack, tp->iss) ||
752 f0cbd3ec bellard
                     SEQ_GT(ti->ti_ack, tp->snd_max)))
753 f0cbd3ec bellard
                        goto dropwithreset;
754 f0cbd3ec bellard
755 f0cbd3ec bellard
                if (tiflags & TH_RST) {
756 f0cbd3ec bellard
                        if (tiflags & TH_ACK)
757 f0cbd3ec bellard
                                tp = tcp_drop(tp,0); /* XXX Check t_softerror! */
758 f0cbd3ec bellard
                        goto drop;
759 f0cbd3ec bellard
                }
760 f0cbd3ec bellard
761 f0cbd3ec bellard
                if ((tiflags & TH_SYN) == 0)
762 f0cbd3ec bellard
                        goto drop;
763 f0cbd3ec bellard
                if (tiflags & TH_ACK) {
764 f0cbd3ec bellard
                        tp->snd_una = ti->ti_ack;
765 f0cbd3ec bellard
                        if (SEQ_LT(tp->snd_nxt, tp->snd_una))
766 f0cbd3ec bellard
                                tp->snd_nxt = tp->snd_una;
767 f0cbd3ec bellard
                }
768 f0cbd3ec bellard
769 f0cbd3ec bellard
                tp->t_timer[TCPT_REXMT] = 0;
770 f0cbd3ec bellard
                tp->irs = ti->ti_seq;
771 f0cbd3ec bellard
                tcp_rcvseqinit(tp);
772 f0cbd3ec bellard
                tp->t_flags |= TF_ACKNOW;
773 f0cbd3ec bellard
                if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
774 31a60e22 blueswir1
                        STAT(tcpstat.tcps_connects++);
775 f0cbd3ec bellard
                        soisfconnected(so);
776 f0cbd3ec bellard
                        tp->t_state = TCPS_ESTABLISHED;
777 3b46e624 ths
778 f0cbd3ec bellard
                        /* Do window scaling on this connection? */
779 f0cbd3ec bellard
/*                        if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
780 f0cbd3ec bellard
 *                                (TF_RCVD_SCALE|TF_REQ_SCALE)) {
781 f0cbd3ec bellard
 *                                 tp->snd_scale = tp->requested_s_scale;
782 f0cbd3ec bellard
 *                                tp->rcv_scale = tp->request_r_scale;
783 f0cbd3ec bellard
 *                        }
784 f0cbd3ec bellard
 */
785 f0cbd3ec bellard
                        (void) tcp_reass(tp, (struct tcpiphdr *)0,
786 f0cbd3ec bellard
                                (struct mbuf *)0);
787 f0cbd3ec bellard
                        /*
788 f0cbd3ec bellard
                         * if we didn't have to retransmit the SYN,
789 f0cbd3ec bellard
                         * use its rtt as our initial srtt & rtt var.
790 f0cbd3ec bellard
                         */
791 f0cbd3ec bellard
                        if (tp->t_rtt)
792 f0cbd3ec bellard
                                tcp_xmit_timer(tp, tp->t_rtt);
793 f0cbd3ec bellard
                } else
794 f0cbd3ec bellard
                        tp->t_state = TCPS_SYN_RECEIVED;
795 f0cbd3ec bellard
796 f0cbd3ec bellard
trimthenstep6:
797 f0cbd3ec bellard
                /*
798 f0cbd3ec bellard
                 * Advance ti->ti_seq to correspond to first data byte.
799 f0cbd3ec bellard
                 * If data, trim to stay within window,
800 f0cbd3ec bellard
                 * dropping FIN if necessary.
801 f0cbd3ec bellard
                 */
802 f0cbd3ec bellard
                ti->ti_seq++;
803 f0cbd3ec bellard
                if (ti->ti_len > tp->rcv_wnd) {
804 f0cbd3ec bellard
                        todrop = ti->ti_len - tp->rcv_wnd;
805 f0cbd3ec bellard
                        m_adj(m, -todrop);
806 f0cbd3ec bellard
                        ti->ti_len = tp->rcv_wnd;
807 f0cbd3ec bellard
                        tiflags &= ~TH_FIN;
808 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvpackafterwin++);
809 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvbyteafterwin += todrop);
810 f0cbd3ec bellard
                }
811 f0cbd3ec bellard
                tp->snd_wl1 = ti->ti_seq - 1;
812 f0cbd3ec bellard
                tp->rcv_up = ti->ti_seq;
813 f0cbd3ec bellard
                goto step6;
814 f0cbd3ec bellard
        } /* switch tp->t_state */
815 f0cbd3ec bellard
        /*
816 f0cbd3ec bellard
         * States other than LISTEN or SYN_SENT.
817 f0cbd3ec bellard
         * First check timestamp, if present.
818 5fafdf24 ths
         * Then check that at least some bytes of segment are within
819 f0cbd3ec bellard
         * receive window.  If segment begins before rcv_nxt,
820 f0cbd3ec bellard
         * drop leading data (and SYN); if nothing left, just ack.
821 5fafdf24 ths
         *
822 f0cbd3ec bellard
         * RFC 1323 PAWS: If we have a timestamp reply on this segment
823 f0cbd3ec bellard
         * and it's less than ts_recent, drop it.
824 f0cbd3ec bellard
         */
825 f0cbd3ec bellard
/*        if (ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent &&
826 f0cbd3ec bellard
 *            TSTMP_LT(ts_val, tp->ts_recent)) {
827 f0cbd3ec bellard
 *
828 f0cbd3ec bellard
 */                /* Check to see if ts_recent is over 24 days old.  */
829 f0cbd3ec bellard
/*                if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) {
830 f0cbd3ec bellard
 */                        /*
831 f0cbd3ec bellard
 *                         * Invalidate ts_recent.  If this segment updates
832 f0cbd3ec bellard
 *                         * ts_recent, the age will be reset later and ts_recent
833 f0cbd3ec bellard
 *                         * will get a valid value.  If it does not, setting
834 f0cbd3ec bellard
 *                         * ts_recent to zero will at least satisfy the
835 f0cbd3ec bellard
 *                         * requirement that zero be placed in the timestamp
836 f0cbd3ec bellard
 *                         * echo reply when ts_recent isn't valid.  The
837 f0cbd3ec bellard
 *                         * age isn't reset until we get a valid ts_recent
838 f0cbd3ec bellard
 *                         * because we don't want out-of-order segments to be
839 f0cbd3ec bellard
 *                         * dropped when ts_recent is old.
840 f0cbd3ec bellard
 *                         */
841 f0cbd3ec bellard
/*                        tp->ts_recent = 0;
842 f0cbd3ec bellard
 *                } else {
843 f0cbd3ec bellard
 *                        tcpstat.tcps_rcvduppack++;
844 f0cbd3ec bellard
 *                        tcpstat.tcps_rcvdupbyte += ti->ti_len;
845 f0cbd3ec bellard
 *                        tcpstat.tcps_pawsdrop++;
846 f0cbd3ec bellard
 *                        goto dropafterack;
847 f0cbd3ec bellard
 *                }
848 f0cbd3ec bellard
 *        }
849 f0cbd3ec bellard
 */
850 f0cbd3ec bellard
851 f0cbd3ec bellard
        todrop = tp->rcv_nxt - ti->ti_seq;
852 f0cbd3ec bellard
        if (todrop > 0) {
853 f0cbd3ec bellard
                if (tiflags & TH_SYN) {
854 f0cbd3ec bellard
                        tiflags &= ~TH_SYN;
855 f0cbd3ec bellard
                        ti->ti_seq++;
856 5fafdf24 ths
                        if (ti->ti_urp > 1)
857 f0cbd3ec bellard
                                ti->ti_urp--;
858 f0cbd3ec bellard
                        else
859 f0cbd3ec bellard
                                tiflags &= ~TH_URG;
860 f0cbd3ec bellard
                        todrop--;
861 f0cbd3ec bellard
                }
862 f0cbd3ec bellard
                /*
863 f0cbd3ec bellard
                 * Following if statement from Stevens, vol. 2, p. 960.
864 f0cbd3ec bellard
                 */
865 f0cbd3ec bellard
                if (todrop > ti->ti_len
866 f0cbd3ec bellard
                    || (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) {
867 f0cbd3ec bellard
                        /*
868 f0cbd3ec bellard
                         * Any valid FIN must be to the left of the window.
869 f0cbd3ec bellard
                         * At this point the FIN must be a duplicate or out
870 f0cbd3ec bellard
                         * of sequence; drop it.
871 f0cbd3ec bellard
                         */
872 f0cbd3ec bellard
                        tiflags &= ~TH_FIN;
873 3b46e624 ths
874 f0cbd3ec bellard
                        /*
875 f0cbd3ec bellard
                         * Send an ACK to resynchronize and drop any data.
876 f0cbd3ec bellard
                         * But keep on processing for RST or ACK.
877 f0cbd3ec bellard
                         */
878 f0cbd3ec bellard
                        tp->t_flags |= TF_ACKNOW;
879 f0cbd3ec bellard
                        todrop = ti->ti_len;
880 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvduppack++);
881 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvdupbyte += todrop);
882 f0cbd3ec bellard
                } else {
883 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvpartduppack++);
884 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvpartdupbyte += todrop);
885 f0cbd3ec bellard
                }
886 f0cbd3ec bellard
                m_adj(m, todrop);
887 f0cbd3ec bellard
                ti->ti_seq += todrop;
888 f0cbd3ec bellard
                ti->ti_len -= todrop;
889 f0cbd3ec bellard
                if (ti->ti_urp > todrop)
890 f0cbd3ec bellard
                        ti->ti_urp -= todrop;
891 f0cbd3ec bellard
                else {
892 f0cbd3ec bellard
                        tiflags &= ~TH_URG;
893 f0cbd3ec bellard
                        ti->ti_urp = 0;
894 f0cbd3ec bellard
                }
895 f0cbd3ec bellard
        }
896 f0cbd3ec bellard
        /*
897 f0cbd3ec bellard
         * If new data are received on a connection after the
898 f0cbd3ec bellard
         * user processes are gone, then RST the other end.
899 f0cbd3ec bellard
         */
900 f0cbd3ec bellard
        if ((so->so_state & SS_NOFDREF) &&
901 f0cbd3ec bellard
            tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
902 f0cbd3ec bellard
                tp = tcp_close(tp);
903 31a60e22 blueswir1
                STAT(tcpstat.tcps_rcvafterclose++);
904 f0cbd3ec bellard
                goto dropwithreset;
905 f0cbd3ec bellard
        }
906 f0cbd3ec bellard
907 f0cbd3ec bellard
        /*
908 f0cbd3ec bellard
         * If segment ends after window, drop trailing data
909 f0cbd3ec bellard
         * (and PUSH and FIN); if nothing left, just ACK.
910 f0cbd3ec bellard
         */
911 f0cbd3ec bellard
        todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd);
912 f0cbd3ec bellard
        if (todrop > 0) {
913 31a60e22 blueswir1
                STAT(tcpstat.tcps_rcvpackafterwin++);
914 f0cbd3ec bellard
                if (todrop >= ti->ti_len) {
915 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvbyteafterwin += ti->ti_len);
916 f0cbd3ec bellard
                        /*
917 f0cbd3ec bellard
                         * If a new connection request is received
918 f0cbd3ec bellard
                         * while in TIME_WAIT, drop the old connection
919 f0cbd3ec bellard
                         * and start over if the sequence numbers
920 f0cbd3ec bellard
                         * are above the previous ones.
921 f0cbd3ec bellard
                         */
922 f0cbd3ec bellard
                        if (tiflags & TH_SYN &&
923 f0cbd3ec bellard
                            tp->t_state == TCPS_TIME_WAIT &&
924 f0cbd3ec bellard
                            SEQ_GT(ti->ti_seq, tp->rcv_nxt)) {
925 f0cbd3ec bellard
                                iss = tp->rcv_nxt + TCP_ISSINCR;
926 f0cbd3ec bellard
                                tp = tcp_close(tp);
927 f0cbd3ec bellard
                                goto findso;
928 f0cbd3ec bellard
                        }
929 f0cbd3ec bellard
                        /*
930 f0cbd3ec bellard
                         * If window is closed can only take segments at
931 f0cbd3ec bellard
                         * window edge, and have to drop data and PUSH from
932 f0cbd3ec bellard
                         * incoming segments.  Continue processing, but
933 f0cbd3ec bellard
                         * remember to ack.  Otherwise, drop segment
934 f0cbd3ec bellard
                         * and ack.
935 f0cbd3ec bellard
                         */
936 f0cbd3ec bellard
                        if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) {
937 f0cbd3ec bellard
                                tp->t_flags |= TF_ACKNOW;
938 31a60e22 blueswir1
                                STAT(tcpstat.tcps_rcvwinprobe++);
939 f0cbd3ec bellard
                        } else
940 f0cbd3ec bellard
                                goto dropafterack;
941 f0cbd3ec bellard
                } else
942 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvbyteafterwin += todrop);
943 f0cbd3ec bellard
                m_adj(m, -todrop);
944 f0cbd3ec bellard
                ti->ti_len -= todrop;
945 f0cbd3ec bellard
                tiflags &= ~(TH_PUSH|TH_FIN);
946 f0cbd3ec bellard
        }
947 f0cbd3ec bellard
948 f0cbd3ec bellard
        /*
949 f0cbd3ec bellard
         * If last ACK falls within this segment's sequence numbers,
950 f0cbd3ec bellard
         * record its timestamp.
951 f0cbd3ec bellard
         */
952 f0cbd3ec bellard
/*        if (ts_present && SEQ_LEQ(ti->ti_seq, tp->last_ack_sent) &&
953 f0cbd3ec bellard
 *            SEQ_LT(tp->last_ack_sent, ti->ti_seq + ti->ti_len +
954 f0cbd3ec bellard
 *                   ((tiflags & (TH_SYN|TH_FIN)) != 0))) {
955 f0cbd3ec bellard
 *                tp->ts_recent_age = tcp_now;
956 f0cbd3ec bellard
 *                tp->ts_recent = ts_val;
957 f0cbd3ec bellard
 *        }
958 f0cbd3ec bellard
 */
959 f0cbd3ec bellard
960 f0cbd3ec bellard
        /*
961 f0cbd3ec bellard
         * If the RST bit is set examine the state:
962 f0cbd3ec bellard
         *    SYN_RECEIVED STATE:
963 f0cbd3ec bellard
         *        If passive open, return to LISTEN state.
964 f0cbd3ec bellard
         *        If active open, inform user that connection was refused.
965 f0cbd3ec bellard
         *    ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
966 f0cbd3ec bellard
         *        Inform user that connection was reset, and close tcb.
967 f0cbd3ec bellard
         *    CLOSING, LAST_ACK, TIME_WAIT STATES
968 f0cbd3ec bellard
         *        Close the tcb.
969 f0cbd3ec bellard
         */
970 f0cbd3ec bellard
        if (tiflags&TH_RST) switch (tp->t_state) {
971 f0cbd3ec bellard
972 f0cbd3ec bellard
        case TCPS_SYN_RECEIVED:
973 f0cbd3ec bellard
/*                so->so_error = ECONNREFUSED; */
974 f0cbd3ec bellard
                goto close;
975 f0cbd3ec bellard
976 f0cbd3ec bellard
        case TCPS_ESTABLISHED:
977 f0cbd3ec bellard
        case TCPS_FIN_WAIT_1:
978 f0cbd3ec bellard
        case TCPS_FIN_WAIT_2:
979 f0cbd3ec bellard
        case TCPS_CLOSE_WAIT:
980 f0cbd3ec bellard
/*                so->so_error = ECONNRESET; */
981 f0cbd3ec bellard
        close:
982 f0cbd3ec bellard
                tp->t_state = TCPS_CLOSED;
983 31a60e22 blueswir1
                STAT(tcpstat.tcps_drops++);
984 f0cbd3ec bellard
                tp = tcp_close(tp);
985 f0cbd3ec bellard
                goto drop;
986 f0cbd3ec bellard
987 f0cbd3ec bellard
        case TCPS_CLOSING:
988 f0cbd3ec bellard
        case TCPS_LAST_ACK:
989 f0cbd3ec bellard
        case TCPS_TIME_WAIT:
990 f0cbd3ec bellard
                tp = tcp_close(tp);
991 f0cbd3ec bellard
                goto drop;
992 f0cbd3ec bellard
        }
993 f0cbd3ec bellard
994 f0cbd3ec bellard
        /*
995 f0cbd3ec bellard
         * If a SYN is in the window, then this is an
996 f0cbd3ec bellard
         * error and we send an RST and drop the connection.
997 f0cbd3ec bellard
         */
998 f0cbd3ec bellard
        if (tiflags & TH_SYN) {
999 f0cbd3ec bellard
                tp = tcp_drop(tp,0);
1000 f0cbd3ec bellard
                goto dropwithreset;
1001 f0cbd3ec bellard
        }
1002 f0cbd3ec bellard
1003 f0cbd3ec bellard
        /*
1004 f0cbd3ec bellard
         * If the ACK bit is off we drop the segment and return.
1005 f0cbd3ec bellard
         */
1006 f0cbd3ec bellard
        if ((tiflags & TH_ACK) == 0) goto drop;
1007 f0cbd3ec bellard
1008 f0cbd3ec bellard
        /*
1009 f0cbd3ec bellard
         * Ack processing.
1010 f0cbd3ec bellard
         */
1011 f0cbd3ec bellard
        switch (tp->t_state) {
1012 f0cbd3ec bellard
        /*
1013 f0cbd3ec bellard
         * In SYN_RECEIVED state if the ack ACKs our SYN then enter
1014 f0cbd3ec bellard
         * ESTABLISHED state and continue processing, otherwise
1015 f0cbd3ec bellard
         * send an RST.  una<=ack<=max
1016 f0cbd3ec bellard
         */
1017 f0cbd3ec bellard
        case TCPS_SYN_RECEIVED:
1018 f0cbd3ec bellard
1019 f0cbd3ec bellard
                if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
1020 f0cbd3ec bellard
                    SEQ_GT(ti->ti_ack, tp->snd_max))
1021 f0cbd3ec bellard
                        goto dropwithreset;
1022 31a60e22 blueswir1
                STAT(tcpstat.tcps_connects++);
1023 f0cbd3ec bellard
                tp->t_state = TCPS_ESTABLISHED;
1024 5fafdf24 ths
                /*
1025 5fafdf24 ths
                 * The sent SYN is ack'ed with our sequence number +1
1026 5fafdf24 ths
                 * The first data byte already in the buffer will get
1027 f0cbd3ec bellard
                 * lost if no correction is made.  This is only needed for
1028 f0cbd3ec bellard
                 * SS_CTL since the buffer is empty otherwise.
1029 3b46e624 ths
                 * tp->snd_una++; or:
1030 f0cbd3ec bellard
                 */
1031 f0cbd3ec bellard
                tp->snd_una=ti->ti_ack;
1032 f0cbd3ec bellard
                if (so->so_state & SS_CTL) {
1033 f0cbd3ec bellard
                  /* So tcp_ctl reports the right state */
1034 f0cbd3ec bellard
                  ret = tcp_ctl(so);
1035 f0cbd3ec bellard
                  if (ret == 1) {
1036 f0cbd3ec bellard
                    soisfconnected(so);
1037 f0cbd3ec bellard
                    so->so_state &= ~SS_CTL;   /* success XXX */
1038 f0cbd3ec bellard
                  } else if (ret == 2) {
1039 f0cbd3ec bellard
                    so->so_state = SS_NOFDREF; /* CTL_CMD */
1040 f0cbd3ec bellard
                  } else {
1041 f0cbd3ec bellard
                    needoutput = 1;
1042 f0cbd3ec bellard
                    tp->t_state = TCPS_FIN_WAIT_1;
1043 f0cbd3ec bellard
                  }
1044 f0cbd3ec bellard
                } else {
1045 f0cbd3ec bellard
                  soisfconnected(so);
1046 f0cbd3ec bellard
                }
1047 3b46e624 ths
1048 f0cbd3ec bellard
                /* Do window scaling? */
1049 f0cbd3ec bellard
/*                if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
1050 f0cbd3ec bellard
 *                        (TF_RCVD_SCALE|TF_REQ_SCALE)) {
1051 f0cbd3ec bellard
 *                        tp->snd_scale = tp->requested_s_scale;
1052 f0cbd3ec bellard
 *                        tp->rcv_scale = tp->request_r_scale;
1053 f0cbd3ec bellard
 *                }
1054 f0cbd3ec bellard
 */
1055 f0cbd3ec bellard
                (void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0);
1056 f0cbd3ec bellard
                tp->snd_wl1 = ti->ti_seq - 1;
1057 f0cbd3ec bellard
                /* Avoid ack processing; snd_una==ti_ack  =>  dup ack */
1058 f0cbd3ec bellard
                goto synrx_to_est;
1059 f0cbd3ec bellard
                /* fall into ... */
1060 f0cbd3ec bellard
1061 f0cbd3ec bellard
        /*
1062 f0cbd3ec bellard
         * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
1063 f0cbd3ec bellard
         * ACKs.  If the ack is in the range
1064 f0cbd3ec bellard
         *        tp->snd_una < ti->ti_ack <= tp->snd_max
1065 f0cbd3ec bellard
         * then advance tp->snd_una to ti->ti_ack and drop
1066 f0cbd3ec bellard
         * data from the retransmission queue.  If this ACK reflects
1067 f0cbd3ec bellard
         * more up to date window information we update our window information.
1068 f0cbd3ec bellard
         */
1069 f0cbd3ec bellard
        case TCPS_ESTABLISHED:
1070 f0cbd3ec bellard
        case TCPS_FIN_WAIT_1:
1071 f0cbd3ec bellard
        case TCPS_FIN_WAIT_2:
1072 f0cbd3ec bellard
        case TCPS_CLOSE_WAIT:
1073 f0cbd3ec bellard
        case TCPS_CLOSING:
1074 f0cbd3ec bellard
        case TCPS_LAST_ACK:
1075 f0cbd3ec bellard
        case TCPS_TIME_WAIT:
1076 f0cbd3ec bellard
1077 f0cbd3ec bellard
                if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
1078 f0cbd3ec bellard
                        if (ti->ti_len == 0 && tiwin == tp->snd_wnd) {
1079 31a60e22 blueswir1
                          STAT(tcpstat.tcps_rcvdupack++);
1080 f0cbd3ec bellard
                          DEBUG_MISC((dfd," dup ack  m = %lx  so = %lx \n",
1081 f0cbd3ec bellard
                                      (long )m, (long )so));
1082 f0cbd3ec bellard
                                /*
1083 f0cbd3ec bellard
                                 * If we have outstanding data (other than
1084 f0cbd3ec bellard
                                 * a window probe), this is a completely
1085 f0cbd3ec bellard
                                 * duplicate ack (ie, window info didn't
1086 f0cbd3ec bellard
                                 * change), the ack is the biggest we've
1087 f0cbd3ec bellard
                                 * seen and we've seen exactly our rexmt
1088 f0cbd3ec bellard
                                 * threshold of them, assume a packet
1089 f0cbd3ec bellard
                                 * has been dropped and retransmit it.
1090 f0cbd3ec bellard
                                 * Kludge snd_nxt & the congestion
1091 f0cbd3ec bellard
                                 * window so we send only this one
1092 f0cbd3ec bellard
                                 * packet.
1093 f0cbd3ec bellard
                                 *
1094 f0cbd3ec bellard
                                 * We know we're losing at the current
1095 f0cbd3ec bellard
                                 * window size so do congestion avoidance
1096 f0cbd3ec bellard
                                 * (set ssthresh to half the current window
1097 f0cbd3ec bellard
                                 * and pull our congestion window back to
1098 f0cbd3ec bellard
                                 * the new ssthresh).
1099 f0cbd3ec bellard
                                 *
1100 f0cbd3ec bellard
                                 * Dup acks mean that packets have left the
1101 5fafdf24 ths
                                 * network (they're now cached at the receiver)
1102 f0cbd3ec bellard
                                 * so bump cwnd by the amount in the receiver
1103 f0cbd3ec bellard
                                 * to keep a constant cwnd packets in the
1104 f0cbd3ec bellard
                                 * network.
1105 f0cbd3ec bellard
                                 */
1106 f0cbd3ec bellard
                                if (tp->t_timer[TCPT_REXMT] == 0 ||
1107 f0cbd3ec bellard
                                    ti->ti_ack != tp->snd_una)
1108 f0cbd3ec bellard
                                        tp->t_dupacks = 0;
1109 9634d903 blueswir1
                                else if (++tp->t_dupacks == TCPREXMTTHRESH) {
1110 f0cbd3ec bellard
                                        tcp_seq onxt = tp->snd_nxt;
1111 f0cbd3ec bellard
                                        u_int win =
1112 f0cbd3ec bellard
                                            min(tp->snd_wnd, tp->snd_cwnd) / 2 /
1113 f0cbd3ec bellard
                                                tp->t_maxseg;
1114 f0cbd3ec bellard
1115 f0cbd3ec bellard
                                        if (win < 2)
1116 f0cbd3ec bellard
                                                win = 2;
1117 f0cbd3ec bellard
                                        tp->snd_ssthresh = win * tp->t_maxseg;
1118 f0cbd3ec bellard
                                        tp->t_timer[TCPT_REXMT] = 0;
1119 f0cbd3ec bellard
                                        tp->t_rtt = 0;
1120 f0cbd3ec bellard
                                        tp->snd_nxt = ti->ti_ack;
1121 f0cbd3ec bellard
                                        tp->snd_cwnd = tp->t_maxseg;
1122 f0cbd3ec bellard
                                        (void) tcp_output(tp);
1123 f0cbd3ec bellard
                                        tp->snd_cwnd = tp->snd_ssthresh +
1124 f0cbd3ec bellard
                                               tp->t_maxseg * tp->t_dupacks;
1125 f0cbd3ec bellard
                                        if (SEQ_GT(onxt, tp->snd_nxt))
1126 f0cbd3ec bellard
                                                tp->snd_nxt = onxt;
1127 f0cbd3ec bellard
                                        goto drop;
1128 9634d903 blueswir1
                                } else if (tp->t_dupacks > TCPREXMTTHRESH) {
1129 f0cbd3ec bellard
                                        tp->snd_cwnd += tp->t_maxseg;
1130 f0cbd3ec bellard
                                        (void) tcp_output(tp);
1131 f0cbd3ec bellard
                                        goto drop;
1132 f0cbd3ec bellard
                                }
1133 f0cbd3ec bellard
                        } else
1134 f0cbd3ec bellard
                                tp->t_dupacks = 0;
1135 f0cbd3ec bellard
                        break;
1136 f0cbd3ec bellard
                }
1137 f0cbd3ec bellard
        synrx_to_est:
1138 f0cbd3ec bellard
                /*
1139 f0cbd3ec bellard
                 * If the congestion window was inflated to account
1140 f0cbd3ec bellard
                 * for the other side's cached packets, retract it.
1141 f0cbd3ec bellard
                 */
1142 9634d903 blueswir1
                if (tp->t_dupacks > TCPREXMTTHRESH &&
1143 f0cbd3ec bellard
                    tp->snd_cwnd > tp->snd_ssthresh)
1144 f0cbd3ec bellard
                        tp->snd_cwnd = tp->snd_ssthresh;
1145 f0cbd3ec bellard
                tp->t_dupacks = 0;
1146 f0cbd3ec bellard
                if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
1147 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvacktoomuch++);
1148 f0cbd3ec bellard
                        goto dropafterack;
1149 f0cbd3ec bellard
                }
1150 f0cbd3ec bellard
                acked = ti->ti_ack - tp->snd_una;
1151 31a60e22 blueswir1
                STAT(tcpstat.tcps_rcvackpack++);
1152 31a60e22 blueswir1
                STAT(tcpstat.tcps_rcvackbyte += acked);
1153 f0cbd3ec bellard
1154 f0cbd3ec bellard
                /*
1155 f0cbd3ec bellard
                 * If we have a timestamp reply, update smoothed
1156 f0cbd3ec bellard
                 * round trip time.  If no timestamp is present but
1157 f0cbd3ec bellard
                 * transmit timer is running and timed sequence
1158 f0cbd3ec bellard
                 * number was acked, update smoothed round trip time.
1159 f0cbd3ec bellard
                 * Since we now have an rtt measurement, cancel the
1160 f0cbd3ec bellard
                 * timer backoff (cf., Phil Karn's retransmit alg.).
1161 f0cbd3ec bellard
                 * Recompute the initial retransmit timer.
1162 f0cbd3ec bellard
                 */
1163 f0cbd3ec bellard
/*                if (ts_present)
1164 f0cbd3ec bellard
 *                        tcp_xmit_timer(tp, tcp_now-ts_ecr+1);
1165 f0cbd3ec bellard
 *                else
1166 3b46e624 ths
 */
1167 f0cbd3ec bellard
                     if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq))
1168 f0cbd3ec bellard
                        tcp_xmit_timer(tp,tp->t_rtt);
1169 f0cbd3ec bellard
1170 f0cbd3ec bellard
                /*
1171 f0cbd3ec bellard
                 * If all outstanding data is acked, stop retransmit
1172 f0cbd3ec bellard
                 * timer and remember to restart (more output or persist).
1173 f0cbd3ec bellard
                 * If there is more data to be acked, restart retransmit
1174 f0cbd3ec bellard
                 * timer, using current (possibly backed-off) value.
1175 f0cbd3ec bellard
                 */
1176 f0cbd3ec bellard
                if (ti->ti_ack == tp->snd_max) {
1177 f0cbd3ec bellard
                        tp->t_timer[TCPT_REXMT] = 0;
1178 f0cbd3ec bellard
                        needoutput = 1;
1179 f0cbd3ec bellard
                } else if (tp->t_timer[TCPT_PERSIST] == 0)
1180 f0cbd3ec bellard
                        tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
1181 f0cbd3ec bellard
                /*
1182 f0cbd3ec bellard
                 * When new data is acked, open the congestion window.
1183 f0cbd3ec bellard
                 * If the window gives us less than ssthresh packets
1184 f0cbd3ec bellard
                 * in flight, open exponentially (maxseg per packet).
1185 f0cbd3ec bellard
                 * Otherwise open linearly: maxseg per window
1186 f0cbd3ec bellard
                 * (maxseg^2 / cwnd per packet).
1187 f0cbd3ec bellard
                 */
1188 f0cbd3ec bellard
                {
1189 f0cbd3ec bellard
                  register u_int cw = tp->snd_cwnd;
1190 f0cbd3ec bellard
                  register u_int incr = tp->t_maxseg;
1191 f0cbd3ec bellard
1192 f0cbd3ec bellard
                  if (cw > tp->snd_ssthresh)
1193 f0cbd3ec bellard
                    incr = incr * incr / cw;
1194 f0cbd3ec bellard
                  tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale);
1195 f0cbd3ec bellard
                }
1196 f0cbd3ec bellard
                if (acked > so->so_snd.sb_cc) {
1197 f0cbd3ec bellard
                        tp->snd_wnd -= so->so_snd.sb_cc;
1198 f0cbd3ec bellard
                        sbdrop(&so->so_snd, (int )so->so_snd.sb_cc);
1199 f0cbd3ec bellard
                        ourfinisacked = 1;
1200 f0cbd3ec bellard
                } else {
1201 f0cbd3ec bellard
                        sbdrop(&so->so_snd, acked);
1202 f0cbd3ec bellard
                        tp->snd_wnd -= acked;
1203 f0cbd3ec bellard
                        ourfinisacked = 0;
1204 f0cbd3ec bellard
                }
1205 f0cbd3ec bellard
                /*
1206 f0cbd3ec bellard
                 * XXX sowwakup is called when data is acked and there's room for
1207 5fafdf24 ths
                 * for more data... it should read() the socket
1208 f0cbd3ec bellard
                 */
1209 f0cbd3ec bellard
/*                if (so->so_snd.sb_flags & SB_NOTIFY)
1210 f0cbd3ec bellard
 *                        sowwakeup(so);
1211 f0cbd3ec bellard
 */
1212 f0cbd3ec bellard
                tp->snd_una = ti->ti_ack;
1213 f0cbd3ec bellard
                if (SEQ_LT(tp->snd_nxt, tp->snd_una))
1214 f0cbd3ec bellard
                        tp->snd_nxt = tp->snd_una;
1215 f0cbd3ec bellard
1216 f0cbd3ec bellard
                switch (tp->t_state) {
1217 f0cbd3ec bellard
1218 f0cbd3ec bellard
                /*
1219 f0cbd3ec bellard
                 * In FIN_WAIT_1 STATE in addition to the processing
1220 f0cbd3ec bellard
                 * for the ESTABLISHED state if our FIN is now acknowledged
1221 f0cbd3ec bellard
                 * then enter FIN_WAIT_2.
1222 f0cbd3ec bellard
                 */
1223 f0cbd3ec bellard
                case TCPS_FIN_WAIT_1:
1224 f0cbd3ec bellard
                        if (ourfinisacked) {
1225 f0cbd3ec bellard
                                /*
1226 f0cbd3ec bellard
                                 * If we can't receive any more
1227 f0cbd3ec bellard
                                 * data, then closing user can proceed.
1228 f0cbd3ec bellard
                                 * Starting the timer is contrary to the
1229 f0cbd3ec bellard
                                 * specification, but if we don't get a FIN
1230 f0cbd3ec bellard
                                 * we'll hang forever.
1231 f0cbd3ec bellard
                                 */
1232 f0cbd3ec bellard
                                if (so->so_state & SS_FCANTRCVMORE) {
1233 f0cbd3ec bellard
                                        soisfdisconnected(so);
1234 9634d903 blueswir1
                                        tp->t_timer[TCPT_2MSL] = TCP_MAXIDLE;
1235 f0cbd3ec bellard
                                }
1236 f0cbd3ec bellard
                                tp->t_state = TCPS_FIN_WAIT_2;
1237 f0cbd3ec bellard
                        }
1238 f0cbd3ec bellard
                        break;
1239 f0cbd3ec bellard
1240 f0cbd3ec bellard
                 /*
1241 f0cbd3ec bellard
                 * In CLOSING STATE in addition to the processing for
1242 f0cbd3ec bellard
                 * the ESTABLISHED state if the ACK acknowledges our FIN
1243 f0cbd3ec bellard
                 * then enter the TIME-WAIT state, otherwise ignore
1244 f0cbd3ec bellard
                 * the segment.
1245 f0cbd3ec bellard
                 */
1246 f0cbd3ec bellard
                case TCPS_CLOSING:
1247 f0cbd3ec bellard
                        if (ourfinisacked) {
1248 f0cbd3ec bellard
                                tp->t_state = TCPS_TIME_WAIT;
1249 f0cbd3ec bellard
                                tcp_canceltimers(tp);
1250 f0cbd3ec bellard
                                tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1251 f0cbd3ec bellard
                                soisfdisconnected(so);
1252 f0cbd3ec bellard
                        }
1253 f0cbd3ec bellard
                        break;
1254 f0cbd3ec bellard
1255 f0cbd3ec bellard
                /*
1256 f0cbd3ec bellard
                 * In LAST_ACK, we may still be waiting for data to drain
1257 f0cbd3ec bellard
                 * and/or to be acked, as well as for the ack of our FIN.
1258 f0cbd3ec bellard
                 * If our FIN is now acknowledged, delete the TCB,
1259 f0cbd3ec bellard
                 * enter the closed state and return.
1260 f0cbd3ec bellard
                 */
1261 f0cbd3ec bellard
                case TCPS_LAST_ACK:
1262 f0cbd3ec bellard
                        if (ourfinisacked) {
1263 f0cbd3ec bellard
                                tp = tcp_close(tp);
1264 f0cbd3ec bellard
                                goto drop;
1265 f0cbd3ec bellard
                        }
1266 f0cbd3ec bellard
                        break;
1267 f0cbd3ec bellard
1268 f0cbd3ec bellard
                /*
1269 f0cbd3ec bellard
                 * In TIME_WAIT state the only thing that should arrive
1270 f0cbd3ec bellard
                 * is a retransmission of the remote FIN.  Acknowledge
1271 f0cbd3ec bellard
                 * it and restart the finack timer.
1272 f0cbd3ec bellard
                 */
1273 f0cbd3ec bellard
                case TCPS_TIME_WAIT:
1274 f0cbd3ec bellard
                        tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1275 f0cbd3ec bellard
                        goto dropafterack;
1276 f0cbd3ec bellard
                }
1277 f0cbd3ec bellard
        } /* switch(tp->t_state) */
1278 f0cbd3ec bellard
1279 f0cbd3ec bellard
step6:
1280 f0cbd3ec bellard
        /*
1281 f0cbd3ec bellard
         * Update window information.
1282 f0cbd3ec bellard
         * Don't look at window if no ACK: TAC's send garbage on first SYN.
1283 f0cbd3ec bellard
         */
1284 f0cbd3ec bellard
        if ((tiflags & TH_ACK) &&
1285 5fafdf24 ths
            (SEQ_LT(tp->snd_wl1, ti->ti_seq) ||
1286 f0cbd3ec bellard
            (tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) ||
1287 f0cbd3ec bellard
            (tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) {
1288 f0cbd3ec bellard
                /* keep track of pure window updates */
1289 f0cbd3ec bellard
                if (ti->ti_len == 0 &&
1290 f0cbd3ec bellard
                    tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd)
1291 31a60e22 blueswir1
                        STAT(tcpstat.tcps_rcvwinupd++);
1292 f0cbd3ec bellard
                tp->snd_wnd = tiwin;
1293 f0cbd3ec bellard
                tp->snd_wl1 = ti->ti_seq;
1294 f0cbd3ec bellard
                tp->snd_wl2 = ti->ti_ack;
1295 f0cbd3ec bellard
                if (tp->snd_wnd > tp->max_sndwnd)
1296 f0cbd3ec bellard
                        tp->max_sndwnd = tp->snd_wnd;
1297 f0cbd3ec bellard
                needoutput = 1;
1298 f0cbd3ec bellard
        }
1299 f0cbd3ec bellard
1300 f0cbd3ec bellard
        /*
1301 f0cbd3ec bellard
         * Process segments with URG.
1302 f0cbd3ec bellard
         */
1303 f0cbd3ec bellard
        if ((tiflags & TH_URG) && ti->ti_urp &&
1304 f0cbd3ec bellard
            TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1305 f0cbd3ec bellard
                /*
1306 f0cbd3ec bellard
                 * This is a kludge, but if we receive and accept
1307 f0cbd3ec bellard
                 * random urgent pointers, we'll crash in
1308 f0cbd3ec bellard
                 * soreceive.  It's hard to imagine someone
1309 f0cbd3ec bellard
                 * actually wanting to send this much urgent data.
1310 f0cbd3ec bellard
                 */
1311 f0cbd3ec bellard
                if (ti->ti_urp + so->so_rcv.sb_cc > so->so_rcv.sb_datalen) {
1312 f0cbd3ec bellard
                        ti->ti_urp = 0;
1313 f0cbd3ec bellard
                        tiflags &= ~TH_URG;
1314 f0cbd3ec bellard
                        goto dodata;
1315 f0cbd3ec bellard
                }
1316 f0cbd3ec bellard
                /*
1317 f0cbd3ec bellard
                 * If this segment advances the known urgent pointer,
1318 f0cbd3ec bellard
                 * then mark the data stream.  This should not happen
1319 f0cbd3ec bellard
                 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
1320 5fafdf24 ths
                 * a FIN has been received from the remote side.
1321 f0cbd3ec bellard
                 * In these states we ignore the URG.
1322 f0cbd3ec bellard
                 *
1323 f0cbd3ec bellard
                 * According to RFC961 (Assigned Protocols),
1324 f0cbd3ec bellard
                 * the urgent pointer points to the last octet
1325 f0cbd3ec bellard
                 * of urgent data.  We continue, however,
1326 f0cbd3ec bellard
                 * to consider it to indicate the first octet
1327 5fafdf24 ths
                 * of data past the urgent section as the original
1328 f0cbd3ec bellard
                 * spec states (in one of two places).
1329 f0cbd3ec bellard
                 */
1330 f0cbd3ec bellard
                if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
1331 f0cbd3ec bellard
                        tp->rcv_up = ti->ti_seq + ti->ti_urp;
1332 f0cbd3ec bellard
                        so->so_urgc =  so->so_rcv.sb_cc +
1333 f0cbd3ec bellard
                                (tp->rcv_up - tp->rcv_nxt); /* -1; */
1334 f0cbd3ec bellard
                        tp->rcv_up = ti->ti_seq + ti->ti_urp;
1335 3b46e624 ths
1336 f0cbd3ec bellard
                }
1337 f0cbd3ec bellard
        } else
1338 f0cbd3ec bellard
                /*
1339 f0cbd3ec bellard
                 * If no out of band data is expected,
1340 f0cbd3ec bellard
                 * pull receive urgent pointer along
1341 f0cbd3ec bellard
                 * with the receive window.
1342 f0cbd3ec bellard
                 */
1343 f0cbd3ec bellard
                if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
1344 f0cbd3ec bellard
                        tp->rcv_up = tp->rcv_nxt;
1345 f0cbd3ec bellard
dodata:
1346 f0cbd3ec bellard
1347 f0cbd3ec bellard
        /*
1348 f0cbd3ec bellard
         * Process the segment text, merging it into the TCP sequencing queue,
1349 f0cbd3ec bellard
         * and arranging for acknowledgment of receipt if necessary.
1350 f0cbd3ec bellard
         * This process logically involves adjusting tp->rcv_wnd as data
1351 f0cbd3ec bellard
         * is presented to the user (this happens in tcp_usrreq.c,
1352 f0cbd3ec bellard
         * case PRU_RCVD).  If a FIN has already been received on this
1353 f0cbd3ec bellard
         * connection then we just ignore the text.
1354 f0cbd3ec bellard
         */
1355 f0cbd3ec bellard
        if ((ti->ti_len || (tiflags&TH_FIN)) &&
1356 f0cbd3ec bellard
            TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1357 f0cbd3ec bellard
                TCP_REASS(tp, ti, m, so, tiflags);
1358 f0cbd3ec bellard
                /*
1359 f0cbd3ec bellard
                 * Note the amount of data that peer has sent into
1360 f0cbd3ec bellard
                 * our window, in order to estimate the sender's
1361 f0cbd3ec bellard
                 * buffer size.
1362 f0cbd3ec bellard
                 */
1363 f0cbd3ec bellard
                len = so->so_rcv.sb_datalen - (tp->rcv_adv - tp->rcv_nxt);
1364 f0cbd3ec bellard
        } else {
1365 f0cbd3ec bellard
                m_free(m);
1366 f0cbd3ec bellard
                tiflags &= ~TH_FIN;
1367 f0cbd3ec bellard
        }
1368 f0cbd3ec bellard
1369 f0cbd3ec bellard
        /*
1370 f0cbd3ec bellard
         * If FIN is received ACK the FIN and let the user know
1371 f0cbd3ec bellard
         * that the connection is closing.
1372 f0cbd3ec bellard
         */
1373 f0cbd3ec bellard
        if (tiflags & TH_FIN) {
1374 f0cbd3ec bellard
                if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
1375 f0cbd3ec bellard
                        /*
1376 f0cbd3ec bellard
                         * If we receive a FIN we can't send more data,
1377 f0cbd3ec bellard
                         * set it SS_FDRAIN
1378 f0cbd3ec bellard
                         * Shutdown the socket if there is no rx data in the
1379 f0cbd3ec bellard
                         * buffer.
1380 f0cbd3ec bellard
                         * soread() is called on completion of shutdown() and
1381 f0cbd3ec bellard
                         * will got to TCPS_LAST_ACK, and use tcp_output()
1382 f0cbd3ec bellard
                         * to send the FIN.
1383 f0cbd3ec bellard
                         */
1384 f0cbd3ec bellard
/*                        sofcantrcvmore(so); */
1385 f0cbd3ec bellard
                        sofwdrain(so);
1386 3b46e624 ths
1387 f0cbd3ec bellard
                        tp->t_flags |= TF_ACKNOW;
1388 f0cbd3ec bellard
                        tp->rcv_nxt++;
1389 f0cbd3ec bellard
                }
1390 f0cbd3ec bellard
                switch (tp->t_state) {
1391 f0cbd3ec bellard
1392 f0cbd3ec bellard
                 /*
1393 f0cbd3ec bellard
                 * In SYN_RECEIVED and ESTABLISHED STATES
1394 f0cbd3ec bellard
                 * enter the CLOSE_WAIT state.
1395 f0cbd3ec bellard
                 */
1396 f0cbd3ec bellard
                case TCPS_SYN_RECEIVED:
1397 f0cbd3ec bellard
                case TCPS_ESTABLISHED:
1398 f0cbd3ec bellard
                  if(so->so_emu == EMU_CTL)        /* no shutdown on socket */
1399 f0cbd3ec bellard
                    tp->t_state = TCPS_LAST_ACK;
1400 5fafdf24 ths
                  else
1401 f0cbd3ec bellard
                    tp->t_state = TCPS_CLOSE_WAIT;
1402 f0cbd3ec bellard
                  break;
1403 f0cbd3ec bellard
1404 f0cbd3ec bellard
                 /*
1405 f0cbd3ec bellard
                 * If still in FIN_WAIT_1 STATE FIN has not been acked so
1406 f0cbd3ec bellard
                 * enter the CLOSING state.
1407 f0cbd3ec bellard
                 */
1408 f0cbd3ec bellard
                case TCPS_FIN_WAIT_1:
1409 f0cbd3ec bellard
                        tp->t_state = TCPS_CLOSING;
1410 f0cbd3ec bellard
                        break;
1411 f0cbd3ec bellard
1412 f0cbd3ec bellard
                 /*
1413 f0cbd3ec bellard
                 * In FIN_WAIT_2 state enter the TIME_WAIT state,
1414 5fafdf24 ths
                 * starting the time-wait timer, turning off the other
1415 f0cbd3ec bellard
                 * standard timers.
1416 f0cbd3ec bellard
                 */
1417 f0cbd3ec bellard
                case TCPS_FIN_WAIT_2:
1418 f0cbd3ec bellard
                        tp->t_state = TCPS_TIME_WAIT;
1419 f0cbd3ec bellard
                        tcp_canceltimers(tp);
1420 f0cbd3ec bellard
                        tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1421 f0cbd3ec bellard
                        soisfdisconnected(so);
1422 f0cbd3ec bellard
                        break;
1423 f0cbd3ec bellard
1424 f0cbd3ec bellard
                /*
1425 f0cbd3ec bellard
                 * In TIME_WAIT state restart the 2 MSL time_wait timer.
1426 f0cbd3ec bellard
                 */
1427 f0cbd3ec bellard
                case TCPS_TIME_WAIT:
1428 f0cbd3ec bellard
                        tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
1429 f0cbd3ec bellard
                        break;
1430 f0cbd3ec bellard
                }
1431 f0cbd3ec bellard
        }
1432 f0cbd3ec bellard
1433 f0cbd3ec bellard
        /*
1434 f0cbd3ec bellard
         * If this is a small packet, then ACK now - with Nagel
1435 f0cbd3ec bellard
         *      congestion avoidance sender won't send more until
1436 f0cbd3ec bellard
         *      he gets an ACK.
1437 5fafdf24 ths
         *
1438 f0cbd3ec bellard
         * See above.
1439 f0cbd3ec bellard
         */
1440 f0cbd3ec bellard
/*        if (ti->ti_len && (unsigned)ti->ti_len < tp->t_maxseg) {
1441 f0cbd3ec bellard
 */
1442 f0cbd3ec bellard
/*        if ((ti->ti_len && (unsigned)ti->ti_len < tp->t_maxseg &&
1443 f0cbd3ec bellard
 *                (so->so_iptos & IPTOS_LOWDELAY) == 0) ||
1444 f0cbd3ec bellard
 *               ((so->so_iptos & IPTOS_LOWDELAY) &&
1445 f0cbd3ec bellard
 *               ((struct tcpiphdr_2 *)ti)->first_char == (char)27)) {
1446 f0cbd3ec bellard
 */
1447 f0cbd3ec bellard
        if (ti->ti_len && (unsigned)ti->ti_len <= 5 &&
1448 f0cbd3ec bellard
            ((struct tcpiphdr_2 *)ti)->first_char == (char)27) {
1449 f0cbd3ec bellard
                tp->t_flags |= TF_ACKNOW;
1450 f0cbd3ec bellard
        }
1451 f0cbd3ec bellard
1452 f0cbd3ec bellard
        /*
1453 f0cbd3ec bellard
         * Return any desired output.
1454 f0cbd3ec bellard
         */
1455 f0cbd3ec bellard
        if (needoutput || (tp->t_flags & TF_ACKNOW)) {
1456 f0cbd3ec bellard
                (void) tcp_output(tp);
1457 f0cbd3ec bellard
        }
1458 f0cbd3ec bellard
        return;
1459 f0cbd3ec bellard
1460 f0cbd3ec bellard
dropafterack:
1461 f0cbd3ec bellard
        /*
1462 f0cbd3ec bellard
         * Generate an ACK dropping incoming segment if it occupies
1463 f0cbd3ec bellard
         * sequence space, where the ACK reflects our state.
1464 f0cbd3ec bellard
         */
1465 f0cbd3ec bellard
        if (tiflags & TH_RST)
1466 f0cbd3ec bellard
                goto drop;
1467 f0cbd3ec bellard
        m_freem(m);
1468 f0cbd3ec bellard
        tp->t_flags |= TF_ACKNOW;
1469 f0cbd3ec bellard
        (void) tcp_output(tp);
1470 f0cbd3ec bellard
        return;
1471 f0cbd3ec bellard
1472 f0cbd3ec bellard
dropwithreset:
1473 f0cbd3ec bellard
        /* reuses m if m!=NULL, m_free() unnecessary */
1474 f0cbd3ec bellard
        if (tiflags & TH_ACK)
1475 f0cbd3ec bellard
                tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
1476 f0cbd3ec bellard
        else {
1477 f0cbd3ec bellard
                if (tiflags & TH_SYN) ti->ti_len++;
1478 f0cbd3ec bellard
                tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
1479 f0cbd3ec bellard
                    TH_RST|TH_ACK);
1480 f0cbd3ec bellard
        }
1481 f0cbd3ec bellard
1482 f0cbd3ec bellard
        return;
1483 f0cbd3ec bellard
1484 f0cbd3ec bellard
drop:
1485 f0cbd3ec bellard
        /*
1486 f0cbd3ec bellard
         * Drop space held by incoming segment and return.
1487 f0cbd3ec bellard
         */
1488 f0cbd3ec bellard
        m_free(m);
1489 f0cbd3ec bellard
1490 f0cbd3ec bellard
        return;
1491 f0cbd3ec bellard
}
1492 f0cbd3ec bellard
1493 f0cbd3ec bellard
 /* , ts_present, ts_val, ts_ecr) */
1494 f0cbd3ec bellard
/*        int *ts_present;
1495 f0cbd3ec bellard
 *        u_int32_t *ts_val, *ts_ecr;
1496 f0cbd3ec bellard
 */
1497 9634d903 blueswir1
static void
1498 9634d903 blueswir1
tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti)
1499 f0cbd3ec bellard
{
1500 f0cbd3ec bellard
        u_int16_t mss;
1501 f0cbd3ec bellard
        int opt, optlen;
1502 f0cbd3ec bellard
1503 f0cbd3ec bellard
        DEBUG_CALL("tcp_dooptions");
1504 f0cbd3ec bellard
        DEBUG_ARGS((dfd," tp = %lx  cnt=%i \n", (long )tp, cnt));
1505 f0cbd3ec bellard
1506 f0cbd3ec bellard
        for (; cnt > 0; cnt -= optlen, cp += optlen) {
1507 f0cbd3ec bellard
                opt = cp[0];
1508 f0cbd3ec bellard
                if (opt == TCPOPT_EOL)
1509 f0cbd3ec bellard
                        break;
1510 f0cbd3ec bellard
                if (opt == TCPOPT_NOP)
1511 f0cbd3ec bellard
                        optlen = 1;
1512 f0cbd3ec bellard
                else {
1513 f0cbd3ec bellard
                        optlen = cp[1];
1514 f0cbd3ec bellard
                        if (optlen <= 0)
1515 f0cbd3ec bellard
                                break;
1516 f0cbd3ec bellard
                }
1517 f0cbd3ec bellard
                switch (opt) {
1518 f0cbd3ec bellard
1519 f0cbd3ec bellard
                default:
1520 f0cbd3ec bellard
                        continue;
1521 f0cbd3ec bellard
1522 f0cbd3ec bellard
                case TCPOPT_MAXSEG:
1523 f0cbd3ec bellard
                        if (optlen != TCPOLEN_MAXSEG)
1524 f0cbd3ec bellard
                                continue;
1525 f0cbd3ec bellard
                        if (!(ti->ti_flags & TH_SYN))
1526 f0cbd3ec bellard
                                continue;
1527 f0cbd3ec bellard
                        memcpy((char *) &mss, (char *) cp + 2, sizeof(mss));
1528 f0cbd3ec bellard
                        NTOHS(mss);
1529 f0cbd3ec bellard
                        (void) tcp_mss(tp, mss);        /* sets t_maxseg */
1530 f0cbd3ec bellard
                        break;
1531 f0cbd3ec bellard
1532 f0cbd3ec bellard
/*                case TCPOPT_WINDOW:
1533 f0cbd3ec bellard
 *                        if (optlen != TCPOLEN_WINDOW)
1534 f0cbd3ec bellard
 *                                continue;
1535 f0cbd3ec bellard
 *                        if (!(ti->ti_flags & TH_SYN))
1536 f0cbd3ec bellard
 *                                continue;
1537 f0cbd3ec bellard
 *                        tp->t_flags |= TF_RCVD_SCALE;
1538 f0cbd3ec bellard
 *                        tp->requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
1539 f0cbd3ec bellard
 *                        break;
1540 f0cbd3ec bellard
 */
1541 f0cbd3ec bellard
/*                case TCPOPT_TIMESTAMP:
1542 f0cbd3ec bellard
 *                        if (optlen != TCPOLEN_TIMESTAMP)
1543 f0cbd3ec bellard
 *                                continue;
1544 f0cbd3ec bellard
 *                        *ts_present = 1;
1545 f0cbd3ec bellard
 *                        memcpy((char *) ts_val, (char *)cp + 2, sizeof(*ts_val));
1546 f0cbd3ec bellard
 *                        NTOHL(*ts_val);
1547 f0cbd3ec bellard
 *                        memcpy((char *) ts_ecr, (char *)cp + 6, sizeof(*ts_ecr));
1548 f0cbd3ec bellard
 *                        NTOHL(*ts_ecr);
1549 f0cbd3ec bellard
 *
1550 5fafdf24 ths
 */                        /*
1551 f0cbd3ec bellard
 *                         * A timestamp received in a SYN makes
1552 f0cbd3ec bellard
 *                         * it ok to send timestamp requests and replies.
1553 f0cbd3ec bellard
 *                         */
1554 f0cbd3ec bellard
/*                        if (ti->ti_flags & TH_SYN) {
1555 f0cbd3ec bellard
 *                                tp->t_flags |= TF_RCVD_TSTMP;
1556 f0cbd3ec bellard
 *                                tp->ts_recent = *ts_val;
1557 f0cbd3ec bellard
 *                                tp->ts_recent_age = tcp_now;
1558 f0cbd3ec bellard
 *                        }
1559 f0cbd3ec bellard
 */                        break;
1560 f0cbd3ec bellard
                }
1561 f0cbd3ec bellard
        }
1562 f0cbd3ec bellard
}
1563 f0cbd3ec bellard
1564 f0cbd3ec bellard
1565 f0cbd3ec bellard
/*
1566 f0cbd3ec bellard
 * Pull out of band byte out of a segment so
1567 f0cbd3ec bellard
 * it doesn't appear in the user's data queue.
1568 f0cbd3ec bellard
 * It is still reflected in the segment length for
1569 f0cbd3ec bellard
 * sequencing purposes.
1570 f0cbd3ec bellard
 */
1571 f0cbd3ec bellard
1572 f0cbd3ec bellard
#ifdef notdef
1573 f0cbd3ec bellard
1574 f0cbd3ec bellard
void
1575 f0cbd3ec bellard
tcp_pulloutofband(so, ti, m)
1576 f0cbd3ec bellard
        struct socket *so;
1577 f0cbd3ec bellard
        struct tcpiphdr *ti;
1578 f0cbd3ec bellard
        register struct mbuf *m;
1579 f0cbd3ec bellard
{
1580 f0cbd3ec bellard
        int cnt = ti->ti_urp - 1;
1581 5fafdf24 ths
1582 f0cbd3ec bellard
        while (cnt >= 0) {
1583 f0cbd3ec bellard
                if (m->m_len > cnt) {
1584 f0cbd3ec bellard
                        char *cp = mtod(m, caddr_t) + cnt;
1585 f0cbd3ec bellard
                        struct tcpcb *tp = sototcpcb(so);
1586 f0cbd3ec bellard
1587 f0cbd3ec bellard
                        tp->t_iobc = *cp;
1588 f0cbd3ec bellard
                        tp->t_oobflags |= TCPOOB_HAVEDATA;
1589 f0cbd3ec bellard
                        memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1));
1590 f0cbd3ec bellard
                        m->m_len--;
1591 f0cbd3ec bellard
                        return;
1592 f0cbd3ec bellard
                }
1593 f0cbd3ec bellard
                cnt -= m->m_len;
1594 f0cbd3ec bellard
                m = m->m_next; /* XXX WRONG! Fix it! */
1595 f0cbd3ec bellard
                if (m == 0)
1596 f0cbd3ec bellard
                        break;
1597 f0cbd3ec bellard
        }
1598 f0cbd3ec bellard
        panic("tcp_pulloutofband");
1599 f0cbd3ec bellard
}
1600 f0cbd3ec bellard
1601 f0cbd3ec bellard
#endif /* notdef */
1602 f0cbd3ec bellard
1603 f0cbd3ec bellard
/*
1604 f0cbd3ec bellard
 * Collect new round-trip time estimate
1605 f0cbd3ec bellard
 * and update averages and current timeout.
1606 f0cbd3ec bellard
 */
1607 f0cbd3ec bellard
1608 9634d903 blueswir1
static void
1609 9634d903 blueswir1
tcp_xmit_timer(register struct tcpcb *tp, int rtt)
1610 f0cbd3ec bellard
{
1611 f0cbd3ec bellard
        register short delta;
1612 f0cbd3ec bellard
1613 f0cbd3ec bellard
        DEBUG_CALL("tcp_xmit_timer");
1614 f0cbd3ec bellard
        DEBUG_ARG("tp = %lx", (long)tp);
1615 f0cbd3ec bellard
        DEBUG_ARG("rtt = %d", rtt);
1616 5fafdf24 ths
1617 31a60e22 blueswir1
        STAT(tcpstat.tcps_rttupdated++);
1618 f0cbd3ec bellard
        if (tp->t_srtt != 0) {
1619 f0cbd3ec bellard
                /*
1620 f0cbd3ec bellard
                 * srtt is stored as fixed point with 3 bits after the
1621 f0cbd3ec bellard
                 * binary point (i.e., scaled by 8).  The following magic
1622 f0cbd3ec bellard
                 * is equivalent to the smoothing algorithm in rfc793 with
1623 f0cbd3ec bellard
                 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
1624 f0cbd3ec bellard
                 * point).  Adjust rtt to origin 0.
1625 f0cbd3ec bellard
                 */
1626 f0cbd3ec bellard
                delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
1627 f0cbd3ec bellard
                if ((tp->t_srtt += delta) <= 0)
1628 f0cbd3ec bellard
                        tp->t_srtt = 1;
1629 f0cbd3ec bellard
                /*
1630 f0cbd3ec bellard
                 * We accumulate a smoothed rtt variance (actually, a
1631 f0cbd3ec bellard
                 * smoothed mean difference), then set the retransmit
1632 f0cbd3ec bellard
                 * timer to smoothed rtt + 4 times the smoothed variance.
1633 f0cbd3ec bellard
                 * rttvar is stored as fixed point with 2 bits after the
1634 f0cbd3ec bellard
                 * binary point (scaled by 4).  The following is
1635 f0cbd3ec bellard
                 * equivalent to rfc793 smoothing with an alpha of .75
1636 f0cbd3ec bellard
                 * (rttvar = rttvar*3/4 + |delta| / 4).  This replaces
1637 f0cbd3ec bellard
                 * rfc793's wired-in beta.
1638 f0cbd3ec bellard
                 */
1639 f0cbd3ec bellard
                if (delta < 0)
1640 f0cbd3ec bellard
                        delta = -delta;
1641 f0cbd3ec bellard
                delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
1642 f0cbd3ec bellard
                if ((tp->t_rttvar += delta) <= 0)
1643 f0cbd3ec bellard
                        tp->t_rttvar = 1;
1644 f0cbd3ec bellard
        } else {
1645 5fafdf24 ths
                /*
1646 f0cbd3ec bellard
                 * No rtt measurement yet - use the unsmoothed rtt.
1647 f0cbd3ec bellard
                 * Set the variance to half the rtt (so our first
1648 f0cbd3ec bellard
                 * retransmit happens at 3*rtt).
1649 f0cbd3ec bellard
                 */
1650 f0cbd3ec bellard
                tp->t_srtt = rtt << TCP_RTT_SHIFT;
1651 f0cbd3ec bellard
                tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
1652 f0cbd3ec bellard
        }
1653 f0cbd3ec bellard
        tp->t_rtt = 0;
1654 f0cbd3ec bellard
        tp->t_rxtshift = 0;
1655 f0cbd3ec bellard
1656 f0cbd3ec bellard
        /*
1657 f0cbd3ec bellard
         * the retransmit should happen at rtt + 4 * rttvar.
1658 f0cbd3ec bellard
         * Because of the way we do the smoothing, srtt and rttvar
1659 f0cbd3ec bellard
         * will each average +1/2 tick of bias.  When we compute
1660 f0cbd3ec bellard
         * the retransmit timer, we want 1/2 tick of rounding and
1661 f0cbd3ec bellard
         * 1 extra tick because of +-1/2 tick uncertainty in the
1662 f0cbd3ec bellard
         * firing of the timer.  The bias will give us exactly the
1663 f0cbd3ec bellard
         * 1.5 tick we need.  But, because the bias is
1664 f0cbd3ec bellard
         * statistical, we have to test that we don't drop below
1665 f0cbd3ec bellard
         * the minimum feasible timer (which is 2 ticks).
1666 f0cbd3ec bellard
         */
1667 f0cbd3ec bellard
        TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
1668 f0cbd3ec bellard
            (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */
1669 5fafdf24 ths
1670 f0cbd3ec bellard
        /*
1671 f0cbd3ec bellard
         * We received an ack for a packet that wasn't retransmitted;
1672 f0cbd3ec bellard
         * it is probably safe to discard any error indications we've
1673 f0cbd3ec bellard
         * received recently.  This isn't quite right, but close enough
1674 f0cbd3ec bellard
         * for now (a route might have failed after we sent a segment,
1675 f0cbd3ec bellard
         * and the return path might not be symmetrical).
1676 f0cbd3ec bellard
         */
1677 f0cbd3ec bellard
        tp->t_softerror = 0;
1678 f0cbd3ec bellard
}
1679 f0cbd3ec bellard
1680 f0cbd3ec bellard
/*
1681 f0cbd3ec bellard
 * Determine a reasonable value for maxseg size.
1682 f0cbd3ec bellard
 * If the route is known, check route for mtu.
1683 f0cbd3ec bellard
 * If none, use an mss that can be handled on the outgoing
1684 f0cbd3ec bellard
 * interface without forcing IP to fragment; if bigger than
1685 f0cbd3ec bellard
 * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
1686 f0cbd3ec bellard
 * to utilize large mbufs.  If no route is found, route has no mtu,
1687 f0cbd3ec bellard
 * or the destination isn't local, use a default, hopefully conservative
1688 f0cbd3ec bellard
 * size (usually 512 or the default IP max size, but no more than the mtu
1689 f0cbd3ec bellard
 * of the interface), as we can't discover anything about intervening
1690 f0cbd3ec bellard
 * gateways or networks.  We also initialize the congestion/slow start
1691 f0cbd3ec bellard
 * window to be a single segment if the destination isn't local.
1692 f0cbd3ec bellard
 * While looking at the routing entry, we also initialize other path-dependent
1693 f0cbd3ec bellard
 * parameters from pre-set or cached values in the routing entry.
1694 f0cbd3ec bellard
 */
1695 f0cbd3ec bellard
1696 f0cbd3ec bellard
int
1697 511d2b14 blueswir1
tcp_mss(struct tcpcb *tp, u_int offer)
1698 f0cbd3ec bellard
{
1699 f0cbd3ec bellard
        struct socket *so = tp->t_socket;
1700 f0cbd3ec bellard
        int mss;
1701 5fafdf24 ths
1702 f0cbd3ec bellard
        DEBUG_CALL("tcp_mss");
1703 f0cbd3ec bellard
        DEBUG_ARG("tp = %lx", (long)tp);
1704 f0cbd3ec bellard
        DEBUG_ARG("offer = %d", offer);
1705 5fafdf24 ths
1706 9634d903 blueswir1
        mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr);
1707 f0cbd3ec bellard
        if (offer)
1708 f0cbd3ec bellard
                mss = min(mss, offer);
1709 f0cbd3ec bellard
        mss = max(mss, 32);
1710 f0cbd3ec bellard
        if (mss < tp->t_maxseg || offer != 0)
1711 f0cbd3ec bellard
           tp->t_maxseg = mss;
1712 5fafdf24 ths
1713 f0cbd3ec bellard
        tp->snd_cwnd = mss;
1714 5fafdf24 ths
1715 9634d903 blueswir1
        sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ?
1716 9634d903 blueswir1
                                               (mss - (TCP_SNDSPACE % mss)) :
1717 9634d903 blueswir1
                                               0));
1718 9634d903 blueswir1
        sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ?
1719 9634d903 blueswir1
                                               (mss - (TCP_RCVSPACE % mss)) :
1720 9634d903 blueswir1
                                               0));
1721 5fafdf24 ths
1722 f0cbd3ec bellard
        DEBUG_MISC((dfd, " returning mss = %d\n", mss));
1723 5fafdf24 ths
1724 f0cbd3ec bellard
        return mss;
1725 f0cbd3ec bellard
}