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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.
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* 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
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* SUCH DAMAGE.
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*
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* @(#)tcp_input.c 8.5 (Berkeley) 4/10/94
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* tcp_input.c,v 1.10 1994/10/13 18:36:32 wollman Exp
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*/
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/*
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* Changes and additions relating to SLiRP
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* Copyright (c) 1995 Danny Gasparovski.
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*
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* Please read the file COPYRIGHT for the
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* terms and conditions of the copyright.
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*/
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#include <slirp.h> |
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#include "ip_icmp.h" |
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|
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#define TCPREXMTTHRESH 3 |
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|
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#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) |
| 47 |
|
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/* for modulo comparisons of timestamps */
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#define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) |
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#define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) |
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|
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/*
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* Insert segment ti into reassembly queue of tcp with
|
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* control block tp. Return TH_FIN if reassembly now includes
|
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* 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,
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* and the queue is empty), avoiding linkage into and removal
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* from the queue and repetition of various conversions.
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* Set DELACK for segments received in order, but ack immediately
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* when segments are out of order (so fast retransmit can work).
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*/
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#ifdef TCP_ACK_HACK
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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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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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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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} 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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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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} 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;
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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;
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|
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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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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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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.
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*/
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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); |
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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)); |
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m = ti->ti_mbuf; |
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ti = tcpiphdr_next(ti); |
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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) {
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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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} |
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} while (ti != (struct tcpiphdr *)tp && ti->ti_seq == tp->rcv_nxt); |
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return (flags);
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} |
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/*
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* TCP input routine, follows pages 65-76 of the
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* protocol specification dated September, 1981 very closely.
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*/
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void
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tcp_input(struct mbuf *m, int iphlen, struct socket *inso) |
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{
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struct ip save_ip, *ip;
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register struct tcpiphdr *ti; |
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caddr_t optp = NULL;
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int optlen = 0; |
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int len, tlen, off;
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register struct tcpcb *tp = NULL; |
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register int tiflags; |
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struct socket *so = NULL; |
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int todrop, acked, ourfinisacked, needoutput = 0; |
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int iss = 0; |
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u_long tiwin; |
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int ret;
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struct ex_list *ex_ptr;
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Slirp *slirp; |
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|
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DEBUG_CALL("tcp_input");
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DEBUG_ARGS((dfd," m = %8lx iphlen = %2d inso = %lx\n",
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(long )m, iphlen, (long )inso )); |
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|
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/*
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* If called with m == 0, then we're continuing the connect
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*/
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if (m == NULL) { |
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so = inso; |
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slirp = so->slirp; |
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|
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/* Re-set a few variables */
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tp = sototcpcb(so); |
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m = so->so_m; |
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so->so_m = NULL;
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ti = so->so_ti; |
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tiwin = ti->ti_win; |
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tiflags = ti->ti_flags; |
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goto cont_conn;
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} |
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slirp = m->slirp; |
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|
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/*
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* Get IP and TCP header together in first mbuf.
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* Note: IP leaves IP header in first mbuf.
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*/
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ti = mtod(m, struct tcpiphdr *);
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if (iphlen > sizeof(struct ip )) { |
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ip_stripoptions(m, (struct mbuf *)0); |
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iphlen=sizeof(struct ip ); |
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} |
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/* XXX Check if too short */
|
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|
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|
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/*
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* Save a copy of the IP header in case we want restore it
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* for sending an ICMP error message in response.
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*/
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ip=mtod(m, struct ip *);
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save_ip = *ip; |
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save_ip.ip_len+= iphlen; |
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|
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/*
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* Checksum extended TCP header and data.
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*/
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tlen = ((struct ip *)ti)->ip_len;
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tcpiphdr2qlink(ti)->next = tcpiphdr2qlink(ti)->prev = NULL;
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memset(&ti->ti_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr)); |
| 282 |
ti->ti_x1 = 0;
|
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ti->ti_len = htons((uint16_t)tlen); |
| 284 |
len = sizeof(struct ip ) + tlen; |
| 285 |
if(cksum(m, len)) {
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goto drop;
|
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} |
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|
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/*
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* Check that TCP offset makes sense,
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* pull out TCP options and adjust length. XXX
|
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*/
|
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off = ti->ti_off << 2;
|
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if (off < sizeof (struct tcphdr) || off > tlen) { |
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goto drop;
|
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} |
| 297 |
tlen -= off; |
| 298 |
ti->ti_len = tlen; |
| 299 |
if (off > sizeof (struct tcphdr)) { |
| 300 |
optlen = off - sizeof (struct tcphdr); |
| 301 |
optp = mtod(m, caddr_t) + sizeof (struct tcpiphdr); |
| 302 |
} |
| 303 |
tiflags = ti->ti_flags; |
| 304 |
|
| 305 |
/*
|
| 306 |
* Convert TCP protocol specific fields to host format.
|
| 307 |
*/
|
| 308 |
NTOHL(ti->ti_seq); |
| 309 |
NTOHL(ti->ti_ack); |
| 310 |
NTOHS(ti->ti_win); |
| 311 |
NTOHS(ti->ti_urp); |
| 312 |
|
| 313 |
/*
|
| 314 |
* Drop TCP, IP headers and TCP options.
|
| 315 |
*/
|
| 316 |
m->m_data += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); |
| 317 |
m->m_len -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); |
| 318 |
|
| 319 |
if (slirp->restricted) {
|
| 320 |
for (ex_ptr = slirp->exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
|
| 321 |
if (ex_ptr->ex_fport == ti->ti_dport &&
|
| 322 |
ti->ti_dst.s_addr == ex_ptr->ex_addr.s_addr) {
|
| 323 |
break;
|
| 324 |
} |
| 325 |
} |
| 326 |
if (!ex_ptr)
|
| 327 |
goto drop;
|
| 328 |
} |
| 329 |
/*
|
| 330 |
* Locate pcb for segment.
|
| 331 |
*/
|
| 332 |
findso:
|
| 333 |
so = slirp->tcp_last_so; |
| 334 |
if (so->so_fport != ti->ti_dport ||
|
| 335 |
so->so_lport != ti->ti_sport || |
| 336 |
so->so_laddr.s_addr != ti->ti_src.s_addr || |
| 337 |
so->so_faddr.s_addr != ti->ti_dst.s_addr) {
|
| 338 |
so = solookup(&slirp->tcb, ti->ti_src, ti->ti_sport, |
| 339 |
ti->ti_dst, ti->ti_dport); |
| 340 |
if (so)
|
| 341 |
slirp->tcp_last_so = so; |
| 342 |
} |
| 343 |
|
| 344 |
/*
|
| 345 |
* If the state is CLOSED (i.e., TCB does not exist) then
|
| 346 |
* all data in the incoming segment is discarded.
|
| 347 |
* If the TCB exists but is in CLOSED state, it is embryonic,
|
| 348 |
* but should either do a listen or a connect soon.
|
| 349 |
*
|
| 350 |
* state == CLOSED means we've done socreate() but haven't
|
| 351 |
* attached it to a protocol yet...
|
| 352 |
*
|
| 353 |
* XXX If a TCB does not exist, and the TH_SYN flag is
|
| 354 |
* the only flag set, then create a session, mark it
|
| 355 |
* as if it was LISTENING, and continue...
|
| 356 |
*/
|
| 357 |
if (so == NULL) { |
| 358 |
if ((tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) != TH_SYN)
|
| 359 |
goto dropwithreset;
|
| 360 |
|
| 361 |
if ((so = socreate(slirp)) == NULL) |
| 362 |
goto dropwithreset;
|
| 363 |
if (tcp_attach(so) < 0) { |
| 364 |
free(so); /* Not sofree (if it failed, it's not insqued) */
|
| 365 |
goto dropwithreset;
|
| 366 |
} |
| 367 |
|
| 368 |
sbreserve(&so->so_snd, TCP_SNDSPACE); |
| 369 |
sbreserve(&so->so_rcv, TCP_RCVSPACE); |
| 370 |
|
| 371 |
so->so_laddr = ti->ti_src; |
| 372 |
so->so_lport = ti->ti_sport; |
| 373 |
so->so_faddr = ti->ti_dst; |
| 374 |
so->so_fport = ti->ti_dport; |
| 375 |
|
| 376 |
if ((so->so_iptos = tcp_tos(so)) == 0) |
| 377 |
so->so_iptos = ((struct ip *)ti)->ip_tos;
|
| 378 |
|
| 379 |
tp = sototcpcb(so); |
| 380 |
tp->t_state = TCPS_LISTEN; |
| 381 |
} |
| 382 |
|
| 383 |
/*
|
| 384 |
* If this is a still-connecting socket, this probably
|
| 385 |
* a retransmit of the SYN. Whether it's a retransmit SYN
|
| 386 |
* or something else, we nuke it.
|
| 387 |
*/
|
| 388 |
if (so->so_state & SS_ISFCONNECTING)
|
| 389 |
goto drop;
|
| 390 |
|
| 391 |
tp = sototcpcb(so); |
| 392 |
|
| 393 |
/* XXX Should never fail */
|
| 394 |
if (tp == NULL) |
| 395 |
goto dropwithreset;
|
| 396 |
if (tp->t_state == TCPS_CLOSED)
|
| 397 |
goto drop;
|
| 398 |
|
| 399 |
tiwin = ti->ti_win; |
| 400 |
|
| 401 |
/*
|
| 402 |
* Segment received on connection.
|
| 403 |
* Reset idle time and keep-alive timer.
|
| 404 |
*/
|
| 405 |
tp->t_idle = 0;
|
| 406 |
if (SO_OPTIONS)
|
| 407 |
tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL; |
| 408 |
else
|
| 409 |
tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE; |
| 410 |
|
| 411 |
/*
|
| 412 |
* Process options if not in LISTEN state,
|
| 413 |
* else do it below (after getting remote address).
|
| 414 |
*/
|
| 415 |
if (optp && tp->t_state != TCPS_LISTEN)
|
| 416 |
tcp_dooptions(tp, (u_char *)optp, optlen, ti); |
| 417 |
|
| 418 |
/*
|
| 419 |
* Header prediction: check for the two common cases
|
| 420 |
* of a uni-directional data xfer. If the packet has
|
| 421 |
* no control flags, is in-sequence, the window didn't
|
| 422 |
* change and we're not retransmitting, it's a
|
| 423 |
* candidate. If the length is zero and the ack moved
|
| 424 |
* forward, we're the sender side of the xfer. Just
|
| 425 |
* free the data acked & wake any higher level process
|
| 426 |
* that was blocked waiting for space. If the length
|
| 427 |
* is non-zero and the ack didn't move, we're the
|
| 428 |
* receiver side. If we're getting packets in-order
|
| 429 |
* (the reassembly queue is empty), add the data to
|
| 430 |
* the socket buffer and note that we need a delayed ack.
|
| 431 |
*
|
| 432 |
* XXX Some of these tests are not needed
|
| 433 |
* eg: the tiwin == tp->snd_wnd prevents many more
|
| 434 |
* predictions.. with no *real* advantage..
|
| 435 |
*/
|
| 436 |
if (tp->t_state == TCPS_ESTABLISHED &&
|
| 437 |
(tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && |
| 438 |
ti->ti_seq == tp->rcv_nxt && |
| 439 |
tiwin && tiwin == tp->snd_wnd && |
| 440 |
tp->snd_nxt == tp->snd_max) {
|
| 441 |
if (ti->ti_len == 0) { |
| 442 |
if (SEQ_GT(ti->ti_ack, tp->snd_una) &&
|
| 443 |
SEQ_LEQ(ti->ti_ack, tp->snd_max) && |
| 444 |
tp->snd_cwnd >= tp->snd_wnd) {
|
| 445 |
/*
|
| 446 |
* this is a pure ack for outstanding data.
|
| 447 |
*/
|
| 448 |
if (tp->t_rtt &&
|
| 449 |
SEQ_GT(ti->ti_ack, tp->t_rtseq)) |
| 450 |
tcp_xmit_timer(tp, tp->t_rtt); |
| 451 |
acked = ti->ti_ack - tp->snd_una; |
| 452 |
sbdrop(&so->so_snd, acked); |
| 453 |
tp->snd_una = ti->ti_ack; |
| 454 |
m_freem(m); |
| 455 |
|
| 456 |
/*
|
| 457 |
* If all outstanding data are acked, stop
|
| 458 |
* retransmit timer, otherwise restart timer
|
| 459 |
* using current (possibly backed-off) value.
|
| 460 |
* If process is waiting for space,
|
| 461 |
* wakeup/selwakeup/signal. If data
|
| 462 |
* are ready to send, let tcp_output
|
| 463 |
* decide between more output or persist.
|
| 464 |
*/
|
| 465 |
if (tp->snd_una == tp->snd_max)
|
| 466 |
tp->t_timer[TCPT_REXMT] = 0;
|
| 467 |
else if (tp->t_timer[TCPT_PERSIST] == 0) |
| 468 |
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
| 469 |
|
| 470 |
/*
|
| 471 |
* This is called because sowwakeup might have
|
| 472 |
* put data into so_snd. Since we don't so sowwakeup,
|
| 473 |
* we don't need this.. XXX???
|
| 474 |
*/
|
| 475 |
if (so->so_snd.sb_cc)
|
| 476 |
(void) tcp_output(tp);
|
| 477 |
|
| 478 |
return;
|
| 479 |
} |
| 480 |
} else if (ti->ti_ack == tp->snd_una && |
| 481 |
tcpfrag_list_empty(tp) && |
| 482 |
ti->ti_len <= sbspace(&so->so_rcv)) {
|
| 483 |
/*
|
| 484 |
* this is a pure, in-sequence data packet
|
| 485 |
* with nothing on the reassembly queue and
|
| 486 |
* we have enough buffer space to take it.
|
| 487 |
*/
|
| 488 |
tp->rcv_nxt += ti->ti_len; |
| 489 |
/*
|
| 490 |
* Add data to socket buffer.
|
| 491 |
*/
|
| 492 |
if (so->so_emu) {
|
| 493 |
if (tcp_emu(so,m)) sbappend(so, m);
|
| 494 |
} else
|
| 495 |
sbappend(so, m); |
| 496 |
|
| 497 |
/*
|
| 498 |
* If this is a short packet, then ACK now - with Nagel
|
| 499 |
* congestion avoidance sender won't send more until
|
| 500 |
* he gets an ACK.
|
| 501 |
*
|
| 502 |
* It is better to not delay acks at all to maximize
|
| 503 |
* TCP throughput. See RFC 2581.
|
| 504 |
*/
|
| 505 |
tp->t_flags |= TF_ACKNOW; |
| 506 |
tcp_output(tp); |
| 507 |
return;
|
| 508 |
} |
| 509 |
} /* header prediction */
|
| 510 |
/*
|
| 511 |
* Calculate amount of space in receive window,
|
| 512 |
* and then do TCP input processing.
|
| 513 |
* Receive window is amount of space in rcv queue,
|
| 514 |
* but not less than advertised window.
|
| 515 |
*/
|
| 516 |
{ int win;
|
| 517 |
win = sbspace(&so->so_rcv); |
| 518 |
if (win < 0) |
| 519 |
win = 0;
|
| 520 |
tp->rcv_wnd = max(win, (int)(tp->rcv_adv - tp->rcv_nxt));
|
| 521 |
} |
| 522 |
|
| 523 |
switch (tp->t_state) {
|
| 524 |
|
| 525 |
/*
|
| 526 |
* If the state is LISTEN then ignore segment if it contains an RST.
|
| 527 |
* If the segment contains an ACK then it is bad and send a RST.
|
| 528 |
* If it does not contain a SYN then it is not interesting; drop it.
|
| 529 |
* Don't bother responding if the destination was a broadcast.
|
| 530 |
* Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial
|
| 531 |
* tp->iss, and send a segment:
|
| 532 |
* <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
|
| 533 |
* Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss.
|
| 534 |
* Fill in remote peer address fields if not previously specified.
|
| 535 |
* Enter SYN_RECEIVED state, and process any other fields of this
|
| 536 |
* segment in this state.
|
| 537 |
*/
|
| 538 |
case TCPS_LISTEN: {
|
| 539 |
|
| 540 |
if (tiflags & TH_RST)
|
| 541 |
goto drop;
|
| 542 |
if (tiflags & TH_ACK)
|
| 543 |
goto dropwithreset;
|
| 544 |
if ((tiflags & TH_SYN) == 0) |
| 545 |
goto drop;
|
| 546 |
|
| 547 |
/*
|
| 548 |
* This has way too many gotos...
|
| 549 |
* But a bit of spaghetti code never hurt anybody :)
|
| 550 |
*/
|
| 551 |
|
| 552 |
/*
|
| 553 |
* If this is destined for the control address, then flag to
|
| 554 |
* tcp_ctl once connected, otherwise connect
|
| 555 |
*/
|
| 556 |
if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
|
| 557 |
slirp->vnetwork_addr.s_addr) {
|
| 558 |
if (so->so_faddr.s_addr != slirp->vhost_addr.s_addr &&
|
| 559 |
so->so_faddr.s_addr != slirp->vnameserver_addr.s_addr) {
|
| 560 |
/* May be an add exec */
|
| 561 |
for (ex_ptr = slirp->exec_list; ex_ptr;
|
| 562 |
ex_ptr = ex_ptr->ex_next) {
|
| 563 |
if(ex_ptr->ex_fport == so->so_fport &&
|
| 564 |
so->so_faddr.s_addr == ex_ptr->ex_addr.s_addr) {
|
| 565 |
so->so_state |= SS_CTL; |
| 566 |
break;
|
| 567 |
} |
| 568 |
} |
| 569 |
if (so->so_state & SS_CTL) {
|
| 570 |
goto cont_input;
|
| 571 |
} |
| 572 |
} |
| 573 |
/* CTL_ALIAS: Do nothing, tcp_fconnect will be called on it */
|
| 574 |
} |
| 575 |
|
| 576 |
if (so->so_emu & EMU_NOCONNECT) {
|
| 577 |
so->so_emu &= ~EMU_NOCONNECT; |
| 578 |
goto cont_input;
|
| 579 |
} |
| 580 |
|
| 581 |
if((tcp_fconnect(so) == -1) && (errno != EINPROGRESS) && (errno != EWOULDBLOCK)) { |
| 582 |
u_char code=ICMP_UNREACH_NET; |
| 583 |
DEBUG_MISC((dfd," tcp fconnect errno = %d-%s\n",
|
| 584 |
errno,strerror(errno))); |
| 585 |
if(errno == ECONNREFUSED) {
|
| 586 |
/* ACK the SYN, send RST to refuse the connection */
|
| 587 |
tcp_respond(tp, ti, m, ti->ti_seq+1, (tcp_seq)0, |
| 588 |
TH_RST|TH_ACK); |
| 589 |
} else {
|
| 590 |
if(errno == EHOSTUNREACH) code=ICMP_UNREACH_HOST;
|
| 591 |
HTONL(ti->ti_seq); /* restore tcp header */
|
| 592 |
HTONL(ti->ti_ack); |
| 593 |
HTONS(ti->ti_win); |
| 594 |
HTONS(ti->ti_urp); |
| 595 |
m->m_data -= sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); |
| 596 |
m->m_len += sizeof(struct tcpiphdr)+off-sizeof(struct tcphdr); |
| 597 |
*ip=save_ip; |
| 598 |
icmp_error(m, ICMP_UNREACH,code, 0,strerror(errno));
|
| 599 |
} |
| 600 |
tcp_close(tp); |
| 601 |
m_free(m); |
| 602 |
} else {
|
| 603 |
/*
|
| 604 |
* Haven't connected yet, save the current mbuf
|
| 605 |
* and ti, and return
|
| 606 |
* XXX Some OS's don't tell us whether the connect()
|
| 607 |
* succeeded or not. So we must time it out.
|
| 608 |
*/
|
| 609 |
so->so_m = m; |
| 610 |
so->so_ti = ti; |
| 611 |
tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT; |
| 612 |
tp->t_state = TCPS_SYN_RECEIVED; |
| 613 |
} |
| 614 |
return;
|
| 615 |
|
| 616 |
cont_conn:
|
| 617 |
/* m==NULL
|
| 618 |
* Check if the connect succeeded
|
| 619 |
*/
|
| 620 |
if (so->so_state & SS_NOFDREF) {
|
| 621 |
tp = tcp_close(tp); |
| 622 |
goto dropwithreset;
|
| 623 |
} |
| 624 |
cont_input:
|
| 625 |
tcp_template(tp); |
| 626 |
|
| 627 |
if (optp)
|
| 628 |
tcp_dooptions(tp, (u_char *)optp, optlen, ti); |
| 629 |
|
| 630 |
if (iss)
|
| 631 |
tp->iss = iss; |
| 632 |
else
|
| 633 |
tp->iss = slirp->tcp_iss; |
| 634 |
slirp->tcp_iss += TCP_ISSINCR/2;
|
| 635 |
tp->irs = ti->ti_seq; |
| 636 |
tcp_sendseqinit(tp); |
| 637 |
tcp_rcvseqinit(tp); |
| 638 |
tp->t_flags |= TF_ACKNOW; |
| 639 |
tp->t_state = TCPS_SYN_RECEIVED; |
| 640 |
tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT; |
| 641 |
goto trimthenstep6;
|
| 642 |
} /* case TCPS_LISTEN */
|
| 643 |
|
| 644 |
/*
|
| 645 |
* If the state is SYN_SENT:
|
| 646 |
* if seg contains an ACK, but not for our SYN, drop the input.
|
| 647 |
* if seg contains a RST, then drop the connection.
|
| 648 |
* if seg does not contain SYN, then drop it.
|
| 649 |
* Otherwise this is an acceptable SYN segment
|
| 650 |
* initialize tp->rcv_nxt and tp->irs
|
| 651 |
* if seg contains ack then advance tp->snd_una
|
| 652 |
* if SYN has been acked change to ESTABLISHED else SYN_RCVD state
|
| 653 |
* arrange for segment to be acked (eventually)
|
| 654 |
* continue processing rest of data/controls, beginning with URG
|
| 655 |
*/
|
| 656 |
case TCPS_SYN_SENT:
|
| 657 |
if ((tiflags & TH_ACK) &&
|
| 658 |
(SEQ_LEQ(ti->ti_ack, tp->iss) || |
| 659 |
SEQ_GT(ti->ti_ack, tp->snd_max))) |
| 660 |
goto dropwithreset;
|
| 661 |
|
| 662 |
if (tiflags & TH_RST) {
|
| 663 |
if (tiflags & TH_ACK) {
|
| 664 |
tcp_drop(tp, 0); /* XXX Check t_softerror! */ |
| 665 |
} |
| 666 |
goto drop;
|
| 667 |
} |
| 668 |
|
| 669 |
if ((tiflags & TH_SYN) == 0) |
| 670 |
goto drop;
|
| 671 |
if (tiflags & TH_ACK) {
|
| 672 |
tp->snd_una = ti->ti_ack; |
| 673 |
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
| 674 |
tp->snd_nxt = tp->snd_una; |
| 675 |
} |
| 676 |
|
| 677 |
tp->t_timer[TCPT_REXMT] = 0;
|
| 678 |
tp->irs = ti->ti_seq; |
| 679 |
tcp_rcvseqinit(tp); |
| 680 |
tp->t_flags |= TF_ACKNOW; |
| 681 |
if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
|
| 682 |
soisfconnected(so); |
| 683 |
tp->t_state = TCPS_ESTABLISHED; |
| 684 |
|
| 685 |
(void) tcp_reass(tp, (struct tcpiphdr *)0, |
| 686 |
(struct mbuf *)0); |
| 687 |
/*
|
| 688 |
* if we didn't have to retransmit the SYN,
|
| 689 |
* use its rtt as our initial srtt & rtt var.
|
| 690 |
*/
|
| 691 |
if (tp->t_rtt)
|
| 692 |
tcp_xmit_timer(tp, tp->t_rtt); |
| 693 |
} else
|
| 694 |
tp->t_state = TCPS_SYN_RECEIVED; |
| 695 |
|
| 696 |
trimthenstep6:
|
| 697 |
/*
|
| 698 |
* Advance ti->ti_seq to correspond to first data byte.
|
| 699 |
* If data, trim to stay within window,
|
| 700 |
* dropping FIN if necessary.
|
| 701 |
*/
|
| 702 |
ti->ti_seq++; |
| 703 |
if (ti->ti_len > tp->rcv_wnd) {
|
| 704 |
todrop = ti->ti_len - tp->rcv_wnd; |
| 705 |
m_adj(m, -todrop); |
| 706 |
ti->ti_len = tp->rcv_wnd; |
| 707 |
tiflags &= ~TH_FIN; |
| 708 |
} |
| 709 |
tp->snd_wl1 = ti->ti_seq - 1;
|
| 710 |
tp->rcv_up = ti->ti_seq; |
| 711 |
goto step6;
|
| 712 |
} /* switch tp->t_state */
|
| 713 |
/*
|
| 714 |
* States other than LISTEN or SYN_SENT.
|
| 715 |
* Check that at least some bytes of segment are within
|
| 716 |
* receive window. If segment begins before rcv_nxt,
|
| 717 |
* drop leading data (and SYN); if nothing left, just ack.
|
| 718 |
*/
|
| 719 |
todrop = tp->rcv_nxt - ti->ti_seq; |
| 720 |
if (todrop > 0) { |
| 721 |
if (tiflags & TH_SYN) {
|
| 722 |
tiflags &= ~TH_SYN; |
| 723 |
ti->ti_seq++; |
| 724 |
if (ti->ti_urp > 1) |
| 725 |
ti->ti_urp--; |
| 726 |
else
|
| 727 |
tiflags &= ~TH_URG; |
| 728 |
todrop--; |
| 729 |
} |
| 730 |
/*
|
| 731 |
* Following if statement from Stevens, vol. 2, p. 960.
|
| 732 |
*/
|
| 733 |
if (todrop > ti->ti_len
|
| 734 |
|| (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) {
|
| 735 |
/*
|
| 736 |
* Any valid FIN must be to the left of the window.
|
| 737 |
* At this point the FIN must be a duplicate or out
|
| 738 |
* of sequence; drop it.
|
| 739 |
*/
|
| 740 |
tiflags &= ~TH_FIN; |
| 741 |
|
| 742 |
/*
|
| 743 |
* Send an ACK to resynchronize and drop any data.
|
| 744 |
* But keep on processing for RST or ACK.
|
| 745 |
*/
|
| 746 |
tp->t_flags |= TF_ACKNOW; |
| 747 |
todrop = ti->ti_len; |
| 748 |
} |
| 749 |
m_adj(m, todrop); |
| 750 |
ti->ti_seq += todrop; |
| 751 |
ti->ti_len -= todrop; |
| 752 |
if (ti->ti_urp > todrop)
|
| 753 |
ti->ti_urp -= todrop; |
| 754 |
else {
|
| 755 |
tiflags &= ~TH_URG; |
| 756 |
ti->ti_urp = 0;
|
| 757 |
} |
| 758 |
} |
| 759 |
/*
|
| 760 |
* If new data are received on a connection after the
|
| 761 |
* user processes are gone, then RST the other end.
|
| 762 |
*/
|
| 763 |
if ((so->so_state & SS_NOFDREF) &&
|
| 764 |
tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) {
|
| 765 |
tp = tcp_close(tp); |
| 766 |
goto dropwithreset;
|
| 767 |
} |
| 768 |
|
| 769 |
/*
|
| 770 |
* If segment ends after window, drop trailing data
|
| 771 |
* (and PUSH and FIN); if nothing left, just ACK.
|
| 772 |
*/
|
| 773 |
todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
| 774 |
if (todrop > 0) { |
| 775 |
if (todrop >= ti->ti_len) {
|
| 776 |
/*
|
| 777 |
* If a new connection request is received
|
| 778 |
* while in TIME_WAIT, drop the old connection
|
| 779 |
* and start over if the sequence numbers
|
| 780 |
* are above the previous ones.
|
| 781 |
*/
|
| 782 |
if (tiflags & TH_SYN &&
|
| 783 |
tp->t_state == TCPS_TIME_WAIT && |
| 784 |
SEQ_GT(ti->ti_seq, tp->rcv_nxt)) {
|
| 785 |
iss = tp->rcv_nxt + TCP_ISSINCR; |
| 786 |
tp = tcp_close(tp); |
| 787 |
goto findso;
|
| 788 |
} |
| 789 |
/*
|
| 790 |
* If window is closed can only take segments at
|
| 791 |
* window edge, and have to drop data and PUSH from
|
| 792 |
* incoming segments. Continue processing, but
|
| 793 |
* remember to ack. Otherwise, drop segment
|
| 794 |
* and ack.
|
| 795 |
*/
|
| 796 |
if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) { |
| 797 |
tp->t_flags |= TF_ACKNOW; |
| 798 |
} else {
|
| 799 |
goto dropafterack;
|
| 800 |
} |
| 801 |
} |
| 802 |
m_adj(m, -todrop); |
| 803 |
ti->ti_len -= todrop; |
| 804 |
tiflags &= ~(TH_PUSH|TH_FIN); |
| 805 |
} |
| 806 |
|
| 807 |
/*
|
| 808 |
* If the RST bit is set examine the state:
|
| 809 |
* SYN_RECEIVED STATE:
|
| 810 |
* If passive open, return to LISTEN state.
|
| 811 |
* If active open, inform user that connection was refused.
|
| 812 |
* ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
|
| 813 |
* Inform user that connection was reset, and close tcb.
|
| 814 |
* CLOSING, LAST_ACK, TIME_WAIT STATES
|
| 815 |
* Close the tcb.
|
| 816 |
*/
|
| 817 |
if (tiflags&TH_RST) switch (tp->t_state) { |
| 818 |
|
| 819 |
case TCPS_SYN_RECEIVED:
|
| 820 |
case TCPS_ESTABLISHED:
|
| 821 |
case TCPS_FIN_WAIT_1:
|
| 822 |
case TCPS_FIN_WAIT_2:
|
| 823 |
case TCPS_CLOSE_WAIT:
|
| 824 |
tp->t_state = TCPS_CLOSED; |
| 825 |
tcp_close(tp); |
| 826 |
goto drop;
|
| 827 |
|
| 828 |
case TCPS_CLOSING:
|
| 829 |
case TCPS_LAST_ACK:
|
| 830 |
case TCPS_TIME_WAIT:
|
| 831 |
tcp_close(tp); |
| 832 |
goto drop;
|
| 833 |
} |
| 834 |
|
| 835 |
/*
|
| 836 |
* If a SYN is in the window, then this is an
|
| 837 |
* error and we send an RST and drop the connection.
|
| 838 |
*/
|
| 839 |
if (tiflags & TH_SYN) {
|
| 840 |
tp = tcp_drop(tp,0);
|
| 841 |
goto dropwithreset;
|
| 842 |
} |
| 843 |
|
| 844 |
/*
|
| 845 |
* If the ACK bit is off we drop the segment and return.
|
| 846 |
*/
|
| 847 |
if ((tiflags & TH_ACK) == 0) goto drop; |
| 848 |
|
| 849 |
/*
|
| 850 |
* Ack processing.
|
| 851 |
*/
|
| 852 |
switch (tp->t_state) {
|
| 853 |
/*
|
| 854 |
* In SYN_RECEIVED state if the ack ACKs our SYN then enter
|
| 855 |
* ESTABLISHED state and continue processing, otherwise
|
| 856 |
* send an RST. una<=ack<=max
|
| 857 |
*/
|
| 858 |
case TCPS_SYN_RECEIVED:
|
| 859 |
|
| 860 |
if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
|
| 861 |
SEQ_GT(ti->ti_ack, tp->snd_max)) |
| 862 |
goto dropwithreset;
|
| 863 |
tp->t_state = TCPS_ESTABLISHED; |
| 864 |
/*
|
| 865 |
* The sent SYN is ack'ed with our sequence number +1
|
| 866 |
* The first data byte already in the buffer will get
|
| 867 |
* lost if no correction is made. This is only needed for
|
| 868 |
* SS_CTL since the buffer is empty otherwise.
|
| 869 |
* tp->snd_una++; or:
|
| 870 |
*/
|
| 871 |
tp->snd_una=ti->ti_ack; |
| 872 |
if (so->so_state & SS_CTL) {
|
| 873 |
/* So tcp_ctl reports the right state */
|
| 874 |
ret = tcp_ctl(so); |
| 875 |
if (ret == 1) { |
| 876 |
soisfconnected(so); |
| 877 |
so->so_state &= ~SS_CTL; /* success XXX */
|
| 878 |
} else if (ret == 2) { |
| 879 |
so->so_state &= SS_PERSISTENT_MASK; |
| 880 |
so->so_state |= SS_NOFDREF; /* CTL_CMD */
|
| 881 |
} else {
|
| 882 |
needoutput = 1;
|
| 883 |
tp->t_state = TCPS_FIN_WAIT_1; |
| 884 |
} |
| 885 |
} else {
|
| 886 |
soisfconnected(so); |
| 887 |
} |
| 888 |
|
| 889 |
(void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0); |
| 890 |
tp->snd_wl1 = ti->ti_seq - 1;
|
| 891 |
/* Avoid ack processing; snd_una==ti_ack => dup ack */
|
| 892 |
goto synrx_to_est;
|
| 893 |
/* fall into ... */
|
| 894 |
|
| 895 |
/*
|
| 896 |
* In ESTABLISHED state: drop duplicate ACKs; ACK out of range
|
| 897 |
* ACKs. If the ack is in the range
|
| 898 |
* tp->snd_una < ti->ti_ack <= tp->snd_max
|
| 899 |
* then advance tp->snd_una to ti->ti_ack and drop
|
| 900 |
* data from the retransmission queue. If this ACK reflects
|
| 901 |
* more up to date window information we update our window information.
|
| 902 |
*/
|
| 903 |
case TCPS_ESTABLISHED:
|
| 904 |
case TCPS_FIN_WAIT_1:
|
| 905 |
case TCPS_FIN_WAIT_2:
|
| 906 |
case TCPS_CLOSE_WAIT:
|
| 907 |
case TCPS_CLOSING:
|
| 908 |
case TCPS_LAST_ACK:
|
| 909 |
case TCPS_TIME_WAIT:
|
| 910 |
|
| 911 |
if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
|
| 912 |
if (ti->ti_len == 0 && tiwin == tp->snd_wnd) { |
| 913 |
DEBUG_MISC((dfd," dup ack m = %lx so = %lx \n",
|
| 914 |
(long )m, (long )so)); |
| 915 |
/*
|
| 916 |
* If we have outstanding data (other than
|
| 917 |
* a window probe), this is a completely
|
| 918 |
* duplicate ack (ie, window info didn't
|
| 919 |
* change), the ack is the biggest we've
|
| 920 |
* seen and we've seen exactly our rexmt
|
| 921 |
* threshold of them, assume a packet
|
| 922 |
* has been dropped and retransmit it.
|
| 923 |
* Kludge snd_nxt & the congestion
|
| 924 |
* window so we send only this one
|
| 925 |
* packet.
|
| 926 |
*
|
| 927 |
* We know we're losing at the current
|
| 928 |
* window size so do congestion avoidance
|
| 929 |
* (set ssthresh to half the current window
|
| 930 |
* and pull our congestion window back to
|
| 931 |
* the new ssthresh).
|
| 932 |
*
|
| 933 |
* Dup acks mean that packets have left the
|
| 934 |
* network (they're now cached at the receiver)
|
| 935 |
* so bump cwnd by the amount in the receiver
|
| 936 |
* to keep a constant cwnd packets in the
|
| 937 |
* network.
|
| 938 |
*/
|
| 939 |
if (tp->t_timer[TCPT_REXMT] == 0 || |
| 940 |
ti->ti_ack != tp->snd_una) |
| 941 |
tp->t_dupacks = 0;
|
| 942 |
else if (++tp->t_dupacks == TCPREXMTTHRESH) { |
| 943 |
tcp_seq onxt = tp->snd_nxt; |
| 944 |
u_int win = |
| 945 |
min(tp->snd_wnd, tp->snd_cwnd) / 2 /
|
| 946 |
tp->t_maxseg; |
| 947 |
|
| 948 |
if (win < 2) |
| 949 |
win = 2;
|
| 950 |
tp->snd_ssthresh = win * tp->t_maxseg; |
| 951 |
tp->t_timer[TCPT_REXMT] = 0;
|
| 952 |
tp->t_rtt = 0;
|
| 953 |
tp->snd_nxt = ti->ti_ack; |
| 954 |
tp->snd_cwnd = tp->t_maxseg; |
| 955 |
(void) tcp_output(tp);
|
| 956 |
tp->snd_cwnd = tp->snd_ssthresh + |
| 957 |
tp->t_maxseg * tp->t_dupacks; |
| 958 |
if (SEQ_GT(onxt, tp->snd_nxt))
|
| 959 |
tp->snd_nxt = onxt; |
| 960 |
goto drop;
|
| 961 |
} else if (tp->t_dupacks > TCPREXMTTHRESH) { |
| 962 |
tp->snd_cwnd += tp->t_maxseg; |
| 963 |
(void) tcp_output(tp);
|
| 964 |
goto drop;
|
| 965 |
} |
| 966 |
} else
|
| 967 |
tp->t_dupacks = 0;
|
| 968 |
break;
|
| 969 |
} |
| 970 |
synrx_to_est:
|
| 971 |
/*
|
| 972 |
* If the congestion window was inflated to account
|
| 973 |
* for the other side's cached packets, retract it.
|
| 974 |
*/
|
| 975 |
if (tp->t_dupacks > TCPREXMTTHRESH &&
|
| 976 |
tp->snd_cwnd > tp->snd_ssthresh) |
| 977 |
tp->snd_cwnd = tp->snd_ssthresh; |
| 978 |
tp->t_dupacks = 0;
|
| 979 |
if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
|
| 980 |
goto dropafterack;
|
| 981 |
} |
| 982 |
acked = ti->ti_ack - tp->snd_una; |
| 983 |
|
| 984 |
/*
|
| 985 |
* If transmit timer is running and timed sequence
|
| 986 |
* number was acked, update smoothed round trip time.
|
| 987 |
* Since we now have an rtt measurement, cancel the
|
| 988 |
* timer backoff (cf., Phil Karn's retransmit alg.).
|
| 989 |
* Recompute the initial retransmit timer.
|
| 990 |
*/
|
| 991 |
if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq))
|
| 992 |
tcp_xmit_timer(tp,tp->t_rtt); |
| 993 |
|
| 994 |
/*
|
| 995 |
* If all outstanding data is acked, stop retransmit
|
| 996 |
* timer and remember to restart (more output or persist).
|
| 997 |
* If there is more data to be acked, restart retransmit
|
| 998 |
* timer, using current (possibly backed-off) value.
|
| 999 |
*/
|
| 1000 |
if (ti->ti_ack == tp->snd_max) {
|
| 1001 |
tp->t_timer[TCPT_REXMT] = 0;
|
| 1002 |
needoutput = 1;
|
| 1003 |
} else if (tp->t_timer[TCPT_PERSIST] == 0) |
| 1004 |
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
| 1005 |
/*
|
| 1006 |
* When new data is acked, open the congestion window.
|
| 1007 |
* If the window gives us less than ssthresh packets
|
| 1008 |
* in flight, open exponentially (maxseg per packet).
|
| 1009 |
* Otherwise open linearly: maxseg per window
|
| 1010 |
* (maxseg^2 / cwnd per packet).
|
| 1011 |
*/
|
| 1012 |
{
|
| 1013 |
register u_int cw = tp->snd_cwnd;
|
| 1014 |
register u_int incr = tp->t_maxseg;
|
| 1015 |
|
| 1016 |
if (cw > tp->snd_ssthresh)
|
| 1017 |
incr = incr * incr / cw; |
| 1018 |
tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale); |
| 1019 |
} |
| 1020 |
if (acked > so->so_snd.sb_cc) {
|
| 1021 |
tp->snd_wnd -= so->so_snd.sb_cc; |
| 1022 |
sbdrop(&so->so_snd, (int )so->so_snd.sb_cc);
|
| 1023 |
ourfinisacked = 1;
|
| 1024 |
} else {
|
| 1025 |
sbdrop(&so->so_snd, acked); |
| 1026 |
tp->snd_wnd -= acked; |
| 1027 |
ourfinisacked = 0;
|
| 1028 |
} |
| 1029 |
tp->snd_una = ti->ti_ack; |
| 1030 |
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
| 1031 |
tp->snd_nxt = tp->snd_una; |
| 1032 |
|
| 1033 |
switch (tp->t_state) {
|
| 1034 |
|
| 1035 |
/*
|
| 1036 |
* In FIN_WAIT_1 STATE in addition to the processing
|
| 1037 |
* for the ESTABLISHED state if our FIN is now acknowledged
|
| 1038 |
* then enter FIN_WAIT_2.
|
| 1039 |
*/
|
| 1040 |
case TCPS_FIN_WAIT_1:
|
| 1041 |
if (ourfinisacked) {
|
| 1042 |
/*
|
| 1043 |
* If we can't receive any more
|
| 1044 |
* data, then closing user can proceed.
|
| 1045 |
* Starting the timer is contrary to the
|
| 1046 |
* specification, but if we don't get a FIN
|
| 1047 |
* we'll hang forever.
|
| 1048 |
*/
|
| 1049 |
if (so->so_state & SS_FCANTRCVMORE) {
|
| 1050 |
tp->t_timer[TCPT_2MSL] = TCP_MAXIDLE; |
| 1051 |
} |
| 1052 |
tp->t_state = TCPS_FIN_WAIT_2; |
| 1053 |
} |
| 1054 |
break;
|
| 1055 |
|
| 1056 |
/*
|
| 1057 |
* In CLOSING STATE in addition to the processing for
|
| 1058 |
* the ESTABLISHED state if the ACK acknowledges our FIN
|
| 1059 |
* then enter the TIME-WAIT state, otherwise ignore
|
| 1060 |
* the segment.
|
| 1061 |
*/
|
| 1062 |
case TCPS_CLOSING:
|
| 1063 |
if (ourfinisacked) {
|
| 1064 |
tp->t_state = TCPS_TIME_WAIT; |
| 1065 |
tcp_canceltimers(tp); |
| 1066 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
| 1067 |
} |
| 1068 |
break;
|
| 1069 |
|
| 1070 |
/*
|
| 1071 |
* In LAST_ACK, we may still be waiting for data to drain
|
| 1072 |
* and/or to be acked, as well as for the ack of our FIN.
|
| 1073 |
* If our FIN is now acknowledged, delete the TCB,
|
| 1074 |
* enter the closed state and return.
|
| 1075 |
*/
|
| 1076 |
case TCPS_LAST_ACK:
|
| 1077 |
if (ourfinisacked) {
|
| 1078 |
tcp_close(tp); |
| 1079 |
goto drop;
|
| 1080 |
} |
| 1081 |
break;
|
| 1082 |
|
| 1083 |
/*
|
| 1084 |
* In TIME_WAIT state the only thing that should arrive
|
| 1085 |
* is a retransmission of the remote FIN. Acknowledge
|
| 1086 |
* it and restart the finack timer.
|
| 1087 |
*/
|
| 1088 |
case TCPS_TIME_WAIT:
|
| 1089 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
| 1090 |
goto dropafterack;
|
| 1091 |
} |
| 1092 |
} /* switch(tp->t_state) */
|
| 1093 |
|
| 1094 |
step6:
|
| 1095 |
/*
|
| 1096 |
* Update window information.
|
| 1097 |
* Don't look at window if no ACK: TAC's send garbage on first SYN.
|
| 1098 |
*/
|
| 1099 |
if ((tiflags & TH_ACK) &&
|
| 1100 |
(SEQ_LT(tp->snd_wl1, ti->ti_seq) || |
| 1101 |
(tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
| 1102 |
(tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) {
|
| 1103 |
tp->snd_wnd = tiwin; |
| 1104 |
tp->snd_wl1 = ti->ti_seq; |
| 1105 |
tp->snd_wl2 = ti->ti_ack; |
| 1106 |
if (tp->snd_wnd > tp->max_sndwnd)
|
| 1107 |
tp->max_sndwnd = tp->snd_wnd; |
| 1108 |
needoutput = 1;
|
| 1109 |
} |
| 1110 |
|
| 1111 |
/*
|
| 1112 |
* Process segments with URG.
|
| 1113 |
*/
|
| 1114 |
if ((tiflags & TH_URG) && ti->ti_urp &&
|
| 1115 |
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
| 1116 |
/*
|
| 1117 |
* This is a kludge, but if we receive and accept
|
| 1118 |
* random urgent pointers, we'll crash in
|
| 1119 |
* soreceive. It's hard to imagine someone
|
| 1120 |
* actually wanting to send this much urgent data.
|
| 1121 |
*/
|
| 1122 |
if (ti->ti_urp + so->so_rcv.sb_cc > so->so_rcv.sb_datalen) {
|
| 1123 |
ti->ti_urp = 0;
|
| 1124 |
tiflags &= ~TH_URG; |
| 1125 |
goto dodata;
|
| 1126 |
} |
| 1127 |
/*
|
| 1128 |
* If this segment advances the known urgent pointer,
|
| 1129 |
* then mark the data stream. This should not happen
|
| 1130 |
* in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
|
| 1131 |
* a FIN has been received from the remote side.
|
| 1132 |
* In these states we ignore the URG.
|
| 1133 |
*
|
| 1134 |
* According to RFC961 (Assigned Protocols),
|
| 1135 |
* the urgent pointer points to the last octet
|
| 1136 |
* of urgent data. We continue, however,
|
| 1137 |
* to consider it to indicate the first octet
|
| 1138 |
* of data past the urgent section as the original
|
| 1139 |
* spec states (in one of two places).
|
| 1140 |
*/
|
| 1141 |
if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
|
| 1142 |
tp->rcv_up = ti->ti_seq + ti->ti_urp; |
| 1143 |
so->so_urgc = so->so_rcv.sb_cc + |
| 1144 |
(tp->rcv_up - tp->rcv_nxt); /* -1; */
|
| 1145 |
tp->rcv_up = ti->ti_seq + ti->ti_urp; |
| 1146 |
|
| 1147 |
} |
| 1148 |
} else
|
| 1149 |
/*
|
| 1150 |
* If no out of band data is expected,
|
| 1151 |
* pull receive urgent pointer along
|
| 1152 |
* with the receive window.
|
| 1153 |
*/
|
| 1154 |
if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
|
| 1155 |
tp->rcv_up = tp->rcv_nxt; |
| 1156 |
dodata:
|
| 1157 |
|
| 1158 |
/*
|
| 1159 |
* Process the segment text, merging it into the TCP sequencing queue,
|
| 1160 |
* and arranging for acknowledgment of receipt if necessary.
|
| 1161 |
* This process logically involves adjusting tp->rcv_wnd as data
|
| 1162 |
* is presented to the user (this happens in tcp_usrreq.c,
|
| 1163 |
* case PRU_RCVD). If a FIN has already been received on this
|
| 1164 |
* connection then we just ignore the text.
|
| 1165 |
*/
|
| 1166 |
if ((ti->ti_len || (tiflags&TH_FIN)) &&
|
| 1167 |
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
| 1168 |
TCP_REASS(tp, ti, m, so, tiflags); |
| 1169 |
} else {
|
| 1170 |
m_free(m); |
| 1171 |
tiflags &= ~TH_FIN; |
| 1172 |
} |
| 1173 |
|
| 1174 |
/*
|
| 1175 |
* If FIN is received ACK the FIN and let the user know
|
| 1176 |
* that the connection is closing.
|
| 1177 |
*/
|
| 1178 |
if (tiflags & TH_FIN) {
|
| 1179 |
if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
| 1180 |
/*
|
| 1181 |
* If we receive a FIN we can't send more data,
|
| 1182 |
* set it SS_FDRAIN
|
| 1183 |
* Shutdown the socket if there is no rx data in the
|
| 1184 |
* buffer.
|
| 1185 |
* soread() is called on completion of shutdown() and
|
| 1186 |
* will got to TCPS_LAST_ACK, and use tcp_output()
|
| 1187 |
* to send the FIN.
|
| 1188 |
*/
|
| 1189 |
sofwdrain(so); |
| 1190 |
|
| 1191 |
tp->t_flags |= TF_ACKNOW; |
| 1192 |
tp->rcv_nxt++; |
| 1193 |
} |
| 1194 |
switch (tp->t_state) {
|
| 1195 |
|
| 1196 |
/*
|
| 1197 |
* In SYN_RECEIVED and ESTABLISHED STATES
|
| 1198 |
* enter the CLOSE_WAIT state.
|
| 1199 |
*/
|
| 1200 |
case TCPS_SYN_RECEIVED:
|
| 1201 |
case TCPS_ESTABLISHED:
|
| 1202 |
if(so->so_emu == EMU_CTL) /* no shutdown on socket */ |
| 1203 |
tp->t_state = TCPS_LAST_ACK; |
| 1204 |
else
|
| 1205 |
tp->t_state = TCPS_CLOSE_WAIT; |
| 1206 |
break;
|
| 1207 |
|
| 1208 |
/*
|
| 1209 |
* If still in FIN_WAIT_1 STATE FIN has not been acked so
|
| 1210 |
* enter the CLOSING state.
|
| 1211 |
*/
|
| 1212 |
case TCPS_FIN_WAIT_1:
|
| 1213 |
tp->t_state = TCPS_CLOSING; |
| 1214 |
break;
|
| 1215 |
|
| 1216 |
/*
|
| 1217 |
* In FIN_WAIT_2 state enter the TIME_WAIT state,
|
| 1218 |
* starting the time-wait timer, turning off the other
|
| 1219 |
* standard timers.
|
| 1220 |
*/
|
| 1221 |
case TCPS_FIN_WAIT_2:
|
| 1222 |
tp->t_state = TCPS_TIME_WAIT; |
| 1223 |
tcp_canceltimers(tp); |
| 1224 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
| 1225 |
break;
|
| 1226 |
|
| 1227 |
/*
|
| 1228 |
* In TIME_WAIT state restart the 2 MSL time_wait timer.
|
| 1229 |
*/
|
| 1230 |
case TCPS_TIME_WAIT:
|
| 1231 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
| 1232 |
break;
|
| 1233 |
} |
| 1234 |
} |
| 1235 |
|
| 1236 |
/*
|
| 1237 |
* If this is a small packet, then ACK now - with Nagel
|
| 1238 |
* congestion avoidance sender won't send more until
|
| 1239 |
* he gets an ACK.
|
| 1240 |
*
|
| 1241 |
* See above.
|
| 1242 |
*/
|
| 1243 |
if (ti->ti_len && (unsigned)ti->ti_len <= 5 && |
| 1244 |
((struct tcpiphdr_2 *)ti)->first_char == (char)27) { |
| 1245 |
tp->t_flags |= TF_ACKNOW; |
| 1246 |
} |
| 1247 |
|
| 1248 |
/*
|
| 1249 |
* Return any desired output.
|
| 1250 |
*/
|
| 1251 |
if (needoutput || (tp->t_flags & TF_ACKNOW)) {
|
| 1252 |
(void) tcp_output(tp);
|
| 1253 |
} |
| 1254 |
return;
|
| 1255 |
|
| 1256 |
dropafterack:
|
| 1257 |
/*
|
| 1258 |
* Generate an ACK dropping incoming segment if it occupies
|
| 1259 |
* sequence space, where the ACK reflects our state.
|
| 1260 |
*/
|
| 1261 |
if (tiflags & TH_RST)
|
| 1262 |
goto drop;
|
| 1263 |
m_freem(m); |
| 1264 |
tp->t_flags |= TF_ACKNOW; |
| 1265 |
(void) tcp_output(tp);
|
| 1266 |
return;
|
| 1267 |
|
| 1268 |
dropwithreset:
|
| 1269 |
/* reuses m if m!=NULL, m_free() unnecessary */
|
| 1270 |
if (tiflags & TH_ACK)
|
| 1271 |
tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
|
| 1272 |
else {
|
| 1273 |
if (tiflags & TH_SYN) ti->ti_len++;
|
| 1274 |
tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
|
| 1275 |
TH_RST|TH_ACK); |
| 1276 |
} |
| 1277 |
|
| 1278 |
return;
|
| 1279 |
|
| 1280 |
drop:
|
| 1281 |
/*
|
| 1282 |
* Drop space held by incoming segment and return.
|
| 1283 |
*/
|
| 1284 |
m_free(m); |
| 1285 |
|
| 1286 |
return;
|
| 1287 |
} |
| 1288 |
|
| 1289 |
static void |
| 1290 |
tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti) |
| 1291 |
{
|
| 1292 |
uint16_t mss; |
| 1293 |
int opt, optlen;
|
| 1294 |
|
| 1295 |
DEBUG_CALL("tcp_dooptions");
|
| 1296 |
DEBUG_ARGS((dfd," tp = %lx cnt=%i \n", (long )tp, cnt)); |
| 1297 |
|
| 1298 |
for (; cnt > 0; cnt -= optlen, cp += optlen) { |
| 1299 |
opt = cp[0];
|
| 1300 |
if (opt == TCPOPT_EOL)
|
| 1301 |
break;
|
| 1302 |
if (opt == TCPOPT_NOP)
|
| 1303 |
optlen = 1;
|
| 1304 |
else {
|
| 1305 |
optlen = cp[1];
|
| 1306 |
if (optlen <= 0) |
| 1307 |
break;
|
| 1308 |
} |
| 1309 |
switch (opt) {
|
| 1310 |
|
| 1311 |
default:
|
| 1312 |
continue;
|
| 1313 |
|
| 1314 |
case TCPOPT_MAXSEG:
|
| 1315 |
if (optlen != TCPOLEN_MAXSEG)
|
| 1316 |
continue;
|
| 1317 |
if (!(ti->ti_flags & TH_SYN))
|
| 1318 |
continue;
|
| 1319 |
memcpy((char *) &mss, (char *) cp + 2, sizeof(mss)); |
| 1320 |
NTOHS(mss); |
| 1321 |
(void) tcp_mss(tp, mss); /* sets t_maxseg */ |
| 1322 |
break;
|
| 1323 |
} |
| 1324 |
} |
| 1325 |
} |
| 1326 |
|
| 1327 |
|
| 1328 |
/*
|
| 1329 |
* Pull out of band byte out of a segment so
|
| 1330 |
* it doesn't appear in the user's data queue.
|
| 1331 |
* It is still reflected in the segment length for
|
| 1332 |
* sequencing purposes.
|
| 1333 |
*/
|
| 1334 |
|
| 1335 |
#ifdef notdef
|
| 1336 |
|
| 1337 |
void
|
| 1338 |
tcp_pulloutofband(so, ti, m) |
| 1339 |
struct socket *so;
|
| 1340 |
struct tcpiphdr *ti;
|
| 1341 |
register struct mbuf *m; |
| 1342 |
{
|
| 1343 |
int cnt = ti->ti_urp - 1; |
| 1344 |
|
| 1345 |
while (cnt >= 0) { |
| 1346 |
if (m->m_len > cnt) {
|
| 1347 |
char *cp = mtod(m, caddr_t) + cnt;
|
| 1348 |
struct tcpcb *tp = sototcpcb(so);
|
| 1349 |
|
| 1350 |
tp->t_iobc = *cp; |
| 1351 |
tp->t_oobflags |= TCPOOB_HAVEDATA; |
| 1352 |
memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1)); |
| 1353 |
m->m_len--; |
| 1354 |
return;
|
| 1355 |
} |
| 1356 |
cnt -= m->m_len; |
| 1357 |
m = m->m_next; /* XXX WRONG! Fix it! */
|
| 1358 |
if (m == 0) |
| 1359 |
break;
|
| 1360 |
} |
| 1361 |
panic("tcp_pulloutofband");
|
| 1362 |
} |
| 1363 |
|
| 1364 |
#endif /* notdef */ |
| 1365 |
|
| 1366 |
/*
|
| 1367 |
* Collect new round-trip time estimate
|
| 1368 |
* and update averages and current timeout.
|
| 1369 |
*/
|
| 1370 |
|
| 1371 |
static void |
| 1372 |
tcp_xmit_timer(register struct tcpcb *tp, int rtt) |
| 1373 |
{
|
| 1374 |
register short delta; |
| 1375 |
|
| 1376 |
DEBUG_CALL("tcp_xmit_timer");
|
| 1377 |
DEBUG_ARG("tp = %lx", (long)tp); |
| 1378 |
DEBUG_ARG("rtt = %d", rtt);
|
| 1379 |
|
| 1380 |
if (tp->t_srtt != 0) { |
| 1381 |
/*
|
| 1382 |
* srtt is stored as fixed point with 3 bits after the
|
| 1383 |
* binary point (i.e., scaled by 8). The following magic
|
| 1384 |
* is equivalent to the smoothing algorithm in rfc793 with
|
| 1385 |
* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
|
| 1386 |
* point). Adjust rtt to origin 0.
|
| 1387 |
*/
|
| 1388 |
delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
|
| 1389 |
if ((tp->t_srtt += delta) <= 0) |
| 1390 |
tp->t_srtt = 1;
|
| 1391 |
/*
|
| 1392 |
* We accumulate a smoothed rtt variance (actually, a
|
| 1393 |
* smoothed mean difference), then set the retransmit
|
| 1394 |
* timer to smoothed rtt + 4 times the smoothed variance.
|
| 1395 |
* rttvar is stored as fixed point with 2 bits after the
|
| 1396 |
* binary point (scaled by 4). The following is
|
| 1397 |
* equivalent to rfc793 smoothing with an alpha of .75
|
| 1398 |
* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
|
| 1399 |
* rfc793's wired-in beta.
|
| 1400 |
*/
|
| 1401 |
if (delta < 0) |
| 1402 |
delta = -delta; |
| 1403 |
delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); |
| 1404 |
if ((tp->t_rttvar += delta) <= 0) |
| 1405 |
tp->t_rttvar = 1;
|
| 1406 |
} else {
|
| 1407 |
/*
|
| 1408 |
* No rtt measurement yet - use the unsmoothed rtt.
|
| 1409 |
* Set the variance to half the rtt (so our first
|
| 1410 |
* retransmit happens at 3*rtt).
|
| 1411 |
*/
|
| 1412 |
tp->t_srtt = rtt << TCP_RTT_SHIFT; |
| 1413 |
tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
|
| 1414 |
} |
| 1415 |
tp->t_rtt = 0;
|
| 1416 |
tp->t_rxtshift = 0;
|
| 1417 |
|
| 1418 |
/*
|
| 1419 |
* the retransmit should happen at rtt + 4 * rttvar.
|
| 1420 |
* Because of the way we do the smoothing, srtt and rttvar
|
| 1421 |
* will each average +1/2 tick of bias. When we compute
|
| 1422 |
* the retransmit timer, we want 1/2 tick of rounding and
|
| 1423 |
* 1 extra tick because of +-1/2 tick uncertainty in the
|
| 1424 |
* firing of the timer. The bias will give us exactly the
|
| 1425 |
* 1.5 tick we need. But, because the bias is
|
| 1426 |
* statistical, we have to test that we don't drop below
|
| 1427 |
* the minimum feasible timer (which is 2 ticks).
|
| 1428 |
*/
|
| 1429 |
TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), |
| 1430 |
(short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */ |
| 1431 |
|
| 1432 |
/*
|
| 1433 |
* We received an ack for a packet that wasn't retransmitted;
|
| 1434 |
* it is probably safe to discard any error indications we've
|
| 1435 |
* received recently. This isn't quite right, but close enough
|
| 1436 |
* for now (a route might have failed after we sent a segment,
|
| 1437 |
* and the return path might not be symmetrical).
|
| 1438 |
*/
|
| 1439 |
tp->t_softerror = 0;
|
| 1440 |
} |
| 1441 |
|
| 1442 |
/*
|
| 1443 |
* Determine a reasonable value for maxseg size.
|
| 1444 |
* If the route is known, check route for mtu.
|
| 1445 |
* If none, use an mss that can be handled on the outgoing
|
| 1446 |
* interface without forcing IP to fragment; if bigger than
|
| 1447 |
* an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
|
| 1448 |
* to utilize large mbufs. If no route is found, route has no mtu,
|
| 1449 |
* or the destination isn't local, use a default, hopefully conservative
|
| 1450 |
* size (usually 512 or the default IP max size, but no more than the mtu
|
| 1451 |
* of the interface), as we can't discover anything about intervening
|
| 1452 |
* gateways or networks. We also initialize the congestion/slow start
|
| 1453 |
* window to be a single segment if the destination isn't local.
|
| 1454 |
* While looking at the routing entry, we also initialize other path-dependent
|
| 1455 |
* parameters from pre-set or cached values in the routing entry.
|
| 1456 |
*/
|
| 1457 |
|
| 1458 |
int
|
| 1459 |
tcp_mss(struct tcpcb *tp, u_int offer)
|
| 1460 |
{
|
| 1461 |
struct socket *so = tp->t_socket;
|
| 1462 |
int mss;
|
| 1463 |
|
| 1464 |
DEBUG_CALL("tcp_mss");
|
| 1465 |
DEBUG_ARG("tp = %lx", (long)tp); |
| 1466 |
DEBUG_ARG("offer = %d", offer);
|
| 1467 |
|
| 1468 |
mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr); |
| 1469 |
if (offer)
|
| 1470 |
mss = min(mss, offer); |
| 1471 |
mss = max(mss, 32);
|
| 1472 |
if (mss < tp->t_maxseg || offer != 0) |
| 1473 |
tp->t_maxseg = mss; |
| 1474 |
|
| 1475 |
tp->snd_cwnd = mss; |
| 1476 |
|
| 1477 |
sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ? |
| 1478 |
(mss - (TCP_SNDSPACE % mss)) : |
| 1479 |
0));
|
| 1480 |
sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ? |
| 1481 |
(mss - (TCP_RCVSPACE % mss)) : |
| 1482 |
0));
|
| 1483 |
|
| 1484 |
DEBUG_MISC((dfd, " returning mss = %d\n", mss));
|
| 1485 |
|
| 1486 |
return mss;
|
| 1487 |
} |