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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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#define TCPREXMTTHRESH 3 |
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#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) |
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|
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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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* 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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* 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_free(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_free(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); |
189 |
if (tcpfrag_list_end(ti, tp) || ti->ti_seq != tp->rcv_nxt)
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return (0); |
191 |
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_free(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; |
232 |
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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 )); |
236 |
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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) { |
241 |
so = inso; |
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slirp = so->slirp; |
243 |
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/* Re-set a few variables */
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tp = sototcpcb(so); |
246 |
m = so->so_m; |
247 |
so->so_m = NULL;
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ti = so->so_ti; |
249 |
tiwin = ti->ti_win; |
250 |
tiflags = ti->ti_flags; |
251 |
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goto cont_conn;
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} |
254 |
slirp = m->slirp; |
255 |
|
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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 )) { |
262 |
ip_stripoptions(m, (struct mbuf *)0); |
263 |
iphlen=sizeof(struct ip ); |
264 |
} |
265 |
/* XXX Check if too short */
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266 |
|
267 |
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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; |
274 |
save_ip.ip_len+= iphlen; |
275 |
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276 |
/*
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277 |
* 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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281 |
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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286 |
goto drop;
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287 |
} |
288 |
|
289 |
/*
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290 |
* 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) { |
295 |
goto drop;
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296 |
} |
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 |
/*
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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_free(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 |
tcp_template(tp); |
614 |
} |
615 |
return;
|
616 |
|
617 |
cont_conn:
|
618 |
/* m==NULL
|
619 |
* Check if the connect succeeded
|
620 |
*/
|
621 |
if (so->so_state & SS_NOFDREF) {
|
622 |
tp = tcp_close(tp); |
623 |
goto dropwithreset;
|
624 |
} |
625 |
cont_input:
|
626 |
tcp_template(tp); |
627 |
|
628 |
if (optp)
|
629 |
tcp_dooptions(tp, (u_char *)optp, optlen, ti); |
630 |
|
631 |
if (iss)
|
632 |
tp->iss = iss; |
633 |
else
|
634 |
tp->iss = slirp->tcp_iss; |
635 |
slirp->tcp_iss += TCP_ISSINCR/2;
|
636 |
tp->irs = ti->ti_seq; |
637 |
tcp_sendseqinit(tp); |
638 |
tcp_rcvseqinit(tp); |
639 |
tp->t_flags |= TF_ACKNOW; |
640 |
tp->t_state = TCPS_SYN_RECEIVED; |
641 |
tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT; |
642 |
goto trimthenstep6;
|
643 |
} /* case TCPS_LISTEN */
|
644 |
|
645 |
/*
|
646 |
* If the state is SYN_SENT:
|
647 |
* if seg contains an ACK, but not for our SYN, drop the input.
|
648 |
* if seg contains a RST, then drop the connection.
|
649 |
* if seg does not contain SYN, then drop it.
|
650 |
* Otherwise this is an acceptable SYN segment
|
651 |
* initialize tp->rcv_nxt and tp->irs
|
652 |
* if seg contains ack then advance tp->snd_una
|
653 |
* if SYN has been acked change to ESTABLISHED else SYN_RCVD state
|
654 |
* arrange for segment to be acked (eventually)
|
655 |
* continue processing rest of data/controls, beginning with URG
|
656 |
*/
|
657 |
case TCPS_SYN_SENT:
|
658 |
if ((tiflags & TH_ACK) &&
|
659 |
(SEQ_LEQ(ti->ti_ack, tp->iss) || |
660 |
SEQ_GT(ti->ti_ack, tp->snd_max))) |
661 |
goto dropwithreset;
|
662 |
|
663 |
if (tiflags & TH_RST) {
|
664 |
if (tiflags & TH_ACK) {
|
665 |
tcp_drop(tp, 0); /* XXX Check t_softerror! */ |
666 |
} |
667 |
goto drop;
|
668 |
} |
669 |
|
670 |
if ((tiflags & TH_SYN) == 0) |
671 |
goto drop;
|
672 |
if (tiflags & TH_ACK) {
|
673 |
tp->snd_una = ti->ti_ack; |
674 |
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
675 |
tp->snd_nxt = tp->snd_una; |
676 |
} |
677 |
|
678 |
tp->t_timer[TCPT_REXMT] = 0;
|
679 |
tp->irs = ti->ti_seq; |
680 |
tcp_rcvseqinit(tp); |
681 |
tp->t_flags |= TF_ACKNOW; |
682 |
if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) {
|
683 |
soisfconnected(so); |
684 |
tp->t_state = TCPS_ESTABLISHED; |
685 |
|
686 |
(void) tcp_reass(tp, (struct tcpiphdr *)0, |
687 |
(struct mbuf *)0); |
688 |
/*
|
689 |
* if we didn't have to retransmit the SYN,
|
690 |
* use its rtt as our initial srtt & rtt var.
|
691 |
*/
|
692 |
if (tp->t_rtt)
|
693 |
tcp_xmit_timer(tp, tp->t_rtt); |
694 |
} else
|
695 |
tp->t_state = TCPS_SYN_RECEIVED; |
696 |
|
697 |
trimthenstep6:
|
698 |
/*
|
699 |
* Advance ti->ti_seq to correspond to first data byte.
|
700 |
* If data, trim to stay within window,
|
701 |
* dropping FIN if necessary.
|
702 |
*/
|
703 |
ti->ti_seq++; |
704 |
if (ti->ti_len > tp->rcv_wnd) {
|
705 |
todrop = ti->ti_len - tp->rcv_wnd; |
706 |
m_adj(m, -todrop); |
707 |
ti->ti_len = tp->rcv_wnd; |
708 |
tiflags &= ~TH_FIN; |
709 |
} |
710 |
tp->snd_wl1 = ti->ti_seq - 1;
|
711 |
tp->rcv_up = ti->ti_seq; |
712 |
goto step6;
|
713 |
} /* switch tp->t_state */
|
714 |
/*
|
715 |
* States other than LISTEN or SYN_SENT.
|
716 |
* Check that at least some bytes of segment are within
|
717 |
* receive window. If segment begins before rcv_nxt,
|
718 |
* drop leading data (and SYN); if nothing left, just ack.
|
719 |
*/
|
720 |
todrop = tp->rcv_nxt - ti->ti_seq; |
721 |
if (todrop > 0) { |
722 |
if (tiflags & TH_SYN) {
|
723 |
tiflags &= ~TH_SYN; |
724 |
ti->ti_seq++; |
725 |
if (ti->ti_urp > 1) |
726 |
ti->ti_urp--; |
727 |
else
|
728 |
tiflags &= ~TH_URG; |
729 |
todrop--; |
730 |
} |
731 |
/*
|
732 |
* Following if statement from Stevens, vol. 2, p. 960.
|
733 |
*/
|
734 |
if (todrop > ti->ti_len
|
735 |
|| (todrop == ti->ti_len && (tiflags & TH_FIN) == 0)) {
|
736 |
/*
|
737 |
* Any valid FIN must be to the left of the window.
|
738 |
* At this point the FIN must be a duplicate or out
|
739 |
* of sequence; drop it.
|
740 |
*/
|
741 |
tiflags &= ~TH_FIN; |
742 |
|
743 |
/*
|
744 |
* Send an ACK to resynchronize and drop any data.
|
745 |
* But keep on processing for RST or ACK.
|
746 |
*/
|
747 |
tp->t_flags |= TF_ACKNOW; |
748 |
todrop = ti->ti_len; |
749 |
} |
750 |
m_adj(m, todrop); |
751 |
ti->ti_seq += todrop; |
752 |
ti->ti_len -= todrop; |
753 |
if (ti->ti_urp > todrop)
|
754 |
ti->ti_urp -= todrop; |
755 |
else {
|
756 |
tiflags &= ~TH_URG; |
757 |
ti->ti_urp = 0;
|
758 |
} |
759 |
} |
760 |
/*
|
761 |
* If new data are received on a connection after the
|
762 |
* user processes are gone, then RST the other end.
|
763 |
*/
|
764 |
if ((so->so_state & SS_NOFDREF) &&
|
765 |
tp->t_state > TCPS_CLOSE_WAIT && ti->ti_len) { |
766 |
tp = tcp_close(tp); |
767 |
goto dropwithreset;
|
768 |
} |
769 |
|
770 |
/*
|
771 |
* If segment ends after window, drop trailing data
|
772 |
* (and PUSH and FIN); if nothing left, just ACK.
|
773 |
*/
|
774 |
todrop = (ti->ti_seq+ti->ti_len) - (tp->rcv_nxt+tp->rcv_wnd); |
775 |
if (todrop > 0) { |
776 |
if (todrop >= ti->ti_len) {
|
777 |
/*
|
778 |
* If a new connection request is received
|
779 |
* while in TIME_WAIT, drop the old connection
|
780 |
* and start over if the sequence numbers
|
781 |
* are above the previous ones.
|
782 |
*/
|
783 |
if (tiflags & TH_SYN &&
|
784 |
tp->t_state == TCPS_TIME_WAIT && |
785 |
SEQ_GT(ti->ti_seq, tp->rcv_nxt)) { |
786 |
iss = tp->rcv_nxt + TCP_ISSINCR; |
787 |
tp = tcp_close(tp); |
788 |
goto findso;
|
789 |
} |
790 |
/*
|
791 |
* If window is closed can only take segments at
|
792 |
* window edge, and have to drop data and PUSH from
|
793 |
* incoming segments. Continue processing, but
|
794 |
* remember to ack. Otherwise, drop segment
|
795 |
* and ack.
|
796 |
*/
|
797 |
if (tp->rcv_wnd == 0 && ti->ti_seq == tp->rcv_nxt) { |
798 |
tp->t_flags |= TF_ACKNOW; |
799 |
} else {
|
800 |
goto dropafterack;
|
801 |
} |
802 |
} |
803 |
m_adj(m, -todrop); |
804 |
ti->ti_len -= todrop; |
805 |
tiflags &= ~(TH_PUSH|TH_FIN); |
806 |
} |
807 |
|
808 |
/*
|
809 |
* If the RST bit is set examine the state:
|
810 |
* SYN_RECEIVED STATE:
|
811 |
* If passive open, return to LISTEN state.
|
812 |
* If active open, inform user that connection was refused.
|
813 |
* ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
|
814 |
* Inform user that connection was reset, and close tcb.
|
815 |
* CLOSING, LAST_ACK, TIME_WAIT STATES
|
816 |
* Close the tcb.
|
817 |
*/
|
818 |
if (tiflags&TH_RST) switch (tp->t_state) { |
819 |
|
820 |
case TCPS_SYN_RECEIVED:
|
821 |
case TCPS_ESTABLISHED:
|
822 |
case TCPS_FIN_WAIT_1:
|
823 |
case TCPS_FIN_WAIT_2:
|
824 |
case TCPS_CLOSE_WAIT:
|
825 |
tp->t_state = TCPS_CLOSED; |
826 |
tcp_close(tp); |
827 |
goto drop;
|
828 |
|
829 |
case TCPS_CLOSING:
|
830 |
case TCPS_LAST_ACK:
|
831 |
case TCPS_TIME_WAIT:
|
832 |
tcp_close(tp); |
833 |
goto drop;
|
834 |
} |
835 |
|
836 |
/*
|
837 |
* If a SYN is in the window, then this is an
|
838 |
* error and we send an RST and drop the connection.
|
839 |
*/
|
840 |
if (tiflags & TH_SYN) {
|
841 |
tp = tcp_drop(tp,0);
|
842 |
goto dropwithreset;
|
843 |
} |
844 |
|
845 |
/*
|
846 |
* If the ACK bit is off we drop the segment and return.
|
847 |
*/
|
848 |
if ((tiflags & TH_ACK) == 0) goto drop; |
849 |
|
850 |
/*
|
851 |
* Ack processing.
|
852 |
*/
|
853 |
switch (tp->t_state) {
|
854 |
/*
|
855 |
* In SYN_RECEIVED state if the ack ACKs our SYN then enter
|
856 |
* ESTABLISHED state and continue processing, otherwise
|
857 |
* send an RST. una<=ack<=max
|
858 |
*/
|
859 |
case TCPS_SYN_RECEIVED:
|
860 |
|
861 |
if (SEQ_GT(tp->snd_una, ti->ti_ack) ||
|
862 |
SEQ_GT(ti->ti_ack, tp->snd_max)) |
863 |
goto dropwithreset;
|
864 |
tp->t_state = TCPS_ESTABLISHED; |
865 |
/*
|
866 |
* The sent SYN is ack'ed with our sequence number +1
|
867 |
* The first data byte already in the buffer will get
|
868 |
* lost if no correction is made. This is only needed for
|
869 |
* SS_CTL since the buffer is empty otherwise.
|
870 |
* tp->snd_una++; or:
|
871 |
*/
|
872 |
tp->snd_una=ti->ti_ack; |
873 |
if (so->so_state & SS_CTL) {
|
874 |
/* So tcp_ctl reports the right state */
|
875 |
ret = tcp_ctl(so); |
876 |
if (ret == 1) { |
877 |
soisfconnected(so); |
878 |
so->so_state &= ~SS_CTL; /* success XXX */
|
879 |
} else if (ret == 2) { |
880 |
so->so_state &= SS_PERSISTENT_MASK; |
881 |
so->so_state |= SS_NOFDREF; /* CTL_CMD */
|
882 |
} else {
|
883 |
needoutput = 1;
|
884 |
tp->t_state = TCPS_FIN_WAIT_1; |
885 |
} |
886 |
} else {
|
887 |
soisfconnected(so); |
888 |
} |
889 |
|
890 |
(void) tcp_reass(tp, (struct tcpiphdr *)0, (struct mbuf *)0); |
891 |
tp->snd_wl1 = ti->ti_seq - 1;
|
892 |
/* Avoid ack processing; snd_una==ti_ack => dup ack */
|
893 |
goto synrx_to_est;
|
894 |
/* fall into ... */
|
895 |
|
896 |
/*
|
897 |
* In ESTABLISHED state: drop duplicate ACKs; ACK out of range
|
898 |
* ACKs. If the ack is in the range
|
899 |
* tp->snd_una < ti->ti_ack <= tp->snd_max
|
900 |
* then advance tp->snd_una to ti->ti_ack and drop
|
901 |
* data from the retransmission queue. If this ACK reflects
|
902 |
* more up to date window information we update our window information.
|
903 |
*/
|
904 |
case TCPS_ESTABLISHED:
|
905 |
case TCPS_FIN_WAIT_1:
|
906 |
case TCPS_FIN_WAIT_2:
|
907 |
case TCPS_CLOSE_WAIT:
|
908 |
case TCPS_CLOSING:
|
909 |
case TCPS_LAST_ACK:
|
910 |
case TCPS_TIME_WAIT:
|
911 |
|
912 |
if (SEQ_LEQ(ti->ti_ack, tp->snd_una)) {
|
913 |
if (ti->ti_len == 0 && tiwin == tp->snd_wnd) { |
914 |
DEBUG_MISC((dfd, " dup ack m = %lx so = %lx\n",
|
915 |
(long )m, (long )so)); |
916 |
/*
|
917 |
* If we have outstanding data (other than
|
918 |
* a window probe), this is a completely
|
919 |
* duplicate ack (ie, window info didn't
|
920 |
* change), the ack is the biggest we've
|
921 |
* seen and we've seen exactly our rexmt
|
922 |
* threshold of them, assume a packet
|
923 |
* has been dropped and retransmit it.
|
924 |
* Kludge snd_nxt & the congestion
|
925 |
* window so we send only this one
|
926 |
* packet.
|
927 |
*
|
928 |
* We know we're losing at the current
|
929 |
* window size so do congestion avoidance
|
930 |
* (set ssthresh to half the current window
|
931 |
* and pull our congestion window back to
|
932 |
* the new ssthresh).
|
933 |
*
|
934 |
* Dup acks mean that packets have left the
|
935 |
* network (they're now cached at the receiver)
|
936 |
* so bump cwnd by the amount in the receiver
|
937 |
* to keep a constant cwnd packets in the
|
938 |
* network.
|
939 |
*/
|
940 |
if (tp->t_timer[TCPT_REXMT] == 0 || |
941 |
ti->ti_ack != tp->snd_una) |
942 |
tp->t_dupacks = 0;
|
943 |
else if (++tp->t_dupacks == TCPREXMTTHRESH) { |
944 |
tcp_seq onxt = tp->snd_nxt; |
945 |
u_int win = |
946 |
min(tp->snd_wnd, tp->snd_cwnd) / 2 /
|
947 |
tp->t_maxseg; |
948 |
|
949 |
if (win < 2) |
950 |
win = 2;
|
951 |
tp->snd_ssthresh = win * tp->t_maxseg; |
952 |
tp->t_timer[TCPT_REXMT] = 0;
|
953 |
tp->t_rtt = 0;
|
954 |
tp->snd_nxt = ti->ti_ack; |
955 |
tp->snd_cwnd = tp->t_maxseg; |
956 |
(void) tcp_output(tp);
|
957 |
tp->snd_cwnd = tp->snd_ssthresh + |
958 |
tp->t_maxseg * tp->t_dupacks; |
959 |
if (SEQ_GT(onxt, tp->snd_nxt))
|
960 |
tp->snd_nxt = onxt; |
961 |
goto drop;
|
962 |
} else if (tp->t_dupacks > TCPREXMTTHRESH) { |
963 |
tp->snd_cwnd += tp->t_maxseg; |
964 |
(void) tcp_output(tp);
|
965 |
goto drop;
|
966 |
} |
967 |
} else
|
968 |
tp->t_dupacks = 0;
|
969 |
break;
|
970 |
} |
971 |
synrx_to_est:
|
972 |
/*
|
973 |
* If the congestion window was inflated to account
|
974 |
* for the other side's cached packets, retract it.
|
975 |
*/
|
976 |
if (tp->t_dupacks > TCPREXMTTHRESH &&
|
977 |
tp->snd_cwnd > tp->snd_ssthresh) |
978 |
tp->snd_cwnd = tp->snd_ssthresh; |
979 |
tp->t_dupacks = 0;
|
980 |
if (SEQ_GT(ti->ti_ack, tp->snd_max)) {
|
981 |
goto dropafterack;
|
982 |
} |
983 |
acked = ti->ti_ack - tp->snd_una; |
984 |
|
985 |
/*
|
986 |
* If transmit timer is running and timed sequence
|
987 |
* number was acked, update smoothed round trip time.
|
988 |
* Since we now have an rtt measurement, cancel the
|
989 |
* timer backoff (cf., Phil Karn's retransmit alg.).
|
990 |
* Recompute the initial retransmit timer.
|
991 |
*/
|
992 |
if (tp->t_rtt && SEQ_GT(ti->ti_ack, tp->t_rtseq))
|
993 |
tcp_xmit_timer(tp,tp->t_rtt); |
994 |
|
995 |
/*
|
996 |
* If all outstanding data is acked, stop retransmit
|
997 |
* timer and remember to restart (more output or persist).
|
998 |
* If there is more data to be acked, restart retransmit
|
999 |
* timer, using current (possibly backed-off) value.
|
1000 |
*/
|
1001 |
if (ti->ti_ack == tp->snd_max) {
|
1002 |
tp->t_timer[TCPT_REXMT] = 0;
|
1003 |
needoutput = 1;
|
1004 |
} else if (tp->t_timer[TCPT_PERSIST] == 0) |
1005 |
tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
1006 |
/*
|
1007 |
* When new data is acked, open the congestion window.
|
1008 |
* If the window gives us less than ssthresh packets
|
1009 |
* in flight, open exponentially (maxseg per packet).
|
1010 |
* Otherwise open linearly: maxseg per window
|
1011 |
* (maxseg^2 / cwnd per packet).
|
1012 |
*/
|
1013 |
{ |
1014 |
register u_int cw = tp->snd_cwnd;
|
1015 |
register u_int incr = tp->t_maxseg;
|
1016 |
|
1017 |
if (cw > tp->snd_ssthresh)
|
1018 |
incr = incr * incr / cw; |
1019 |
tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<<tp->snd_scale); |
1020 |
} |
1021 |
if (acked > so->so_snd.sb_cc) {
|
1022 |
tp->snd_wnd -= so->so_snd.sb_cc; |
1023 |
sbdrop(&so->so_snd, (int )so->so_snd.sb_cc);
|
1024 |
ourfinisacked = 1;
|
1025 |
} else {
|
1026 |
sbdrop(&so->so_snd, acked); |
1027 |
tp->snd_wnd -= acked; |
1028 |
ourfinisacked = 0;
|
1029 |
} |
1030 |
tp->snd_una = ti->ti_ack; |
1031 |
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
|
1032 |
tp->snd_nxt = tp->snd_una; |
1033 |
|
1034 |
switch (tp->t_state) {
|
1035 |
|
1036 |
/*
|
1037 |
* In FIN_WAIT_1 STATE in addition to the processing
|
1038 |
* for the ESTABLISHED state if our FIN is now acknowledged
|
1039 |
* then enter FIN_WAIT_2.
|
1040 |
*/
|
1041 |
case TCPS_FIN_WAIT_1:
|
1042 |
if (ourfinisacked) {
|
1043 |
/*
|
1044 |
* If we can't receive any more
|
1045 |
* data, then closing user can proceed.
|
1046 |
* Starting the timer is contrary to the
|
1047 |
* specification, but if we don't get a FIN
|
1048 |
* we'll hang forever.
|
1049 |
*/
|
1050 |
if (so->so_state & SS_FCANTRCVMORE) {
|
1051 |
tp->t_timer[TCPT_2MSL] = TCP_MAXIDLE; |
1052 |
} |
1053 |
tp->t_state = TCPS_FIN_WAIT_2; |
1054 |
} |
1055 |
break;
|
1056 |
|
1057 |
/*
|
1058 |
* In CLOSING STATE in addition to the processing for
|
1059 |
* the ESTABLISHED state if the ACK acknowledges our FIN
|
1060 |
* then enter the TIME-WAIT state, otherwise ignore
|
1061 |
* the segment.
|
1062 |
*/
|
1063 |
case TCPS_CLOSING:
|
1064 |
if (ourfinisacked) {
|
1065 |
tp->t_state = TCPS_TIME_WAIT; |
1066 |
tcp_canceltimers(tp); |
1067 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
1068 |
} |
1069 |
break;
|
1070 |
|
1071 |
/*
|
1072 |
* In LAST_ACK, we may still be waiting for data to drain
|
1073 |
* and/or to be acked, as well as for the ack of our FIN.
|
1074 |
* If our FIN is now acknowledged, delete the TCB,
|
1075 |
* enter the closed state and return.
|
1076 |
*/
|
1077 |
case TCPS_LAST_ACK:
|
1078 |
if (ourfinisacked) {
|
1079 |
tcp_close(tp); |
1080 |
goto drop;
|
1081 |
} |
1082 |
break;
|
1083 |
|
1084 |
/*
|
1085 |
* In TIME_WAIT state the only thing that should arrive
|
1086 |
* is a retransmission of the remote FIN. Acknowledge
|
1087 |
* it and restart the finack timer.
|
1088 |
*/
|
1089 |
case TCPS_TIME_WAIT:
|
1090 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
1091 |
goto dropafterack;
|
1092 |
} |
1093 |
} /* switch(tp->t_state) */
|
1094 |
|
1095 |
step6:
|
1096 |
/*
|
1097 |
* Update window information.
|
1098 |
* Don't look at window if no ACK: TAC's send garbage on first SYN.
|
1099 |
*/
|
1100 |
if ((tiflags & TH_ACK) &&
|
1101 |
(SEQ_LT(tp->snd_wl1, ti->ti_seq) || |
1102 |
(tp->snd_wl1 == ti->ti_seq && (SEQ_LT(tp->snd_wl2, ti->ti_ack) || |
1103 |
(tp->snd_wl2 == ti->ti_ack && tiwin > tp->snd_wnd))))) { |
1104 |
tp->snd_wnd = tiwin; |
1105 |
tp->snd_wl1 = ti->ti_seq; |
1106 |
tp->snd_wl2 = ti->ti_ack; |
1107 |
if (tp->snd_wnd > tp->max_sndwnd)
|
1108 |
tp->max_sndwnd = tp->snd_wnd; |
1109 |
needoutput = 1;
|
1110 |
} |
1111 |
|
1112 |
/*
|
1113 |
* Process segments with URG.
|
1114 |
*/
|
1115 |
if ((tiflags & TH_URG) && ti->ti_urp &&
|
1116 |
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
1117 |
/*
|
1118 |
* This is a kludge, but if we receive and accept
|
1119 |
* random urgent pointers, we'll crash in
|
1120 |
* soreceive. It's hard to imagine someone
|
1121 |
* actually wanting to send this much urgent data.
|
1122 |
*/
|
1123 |
if (ti->ti_urp + so->so_rcv.sb_cc > so->so_rcv.sb_datalen) {
|
1124 |
ti->ti_urp = 0;
|
1125 |
tiflags &= ~TH_URG; |
1126 |
goto dodata;
|
1127 |
} |
1128 |
/*
|
1129 |
* If this segment advances the known urgent pointer,
|
1130 |
* then mark the data stream. This should not happen
|
1131 |
* in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
|
1132 |
* a FIN has been received from the remote side.
|
1133 |
* In these states we ignore the URG.
|
1134 |
*
|
1135 |
* According to RFC961 (Assigned Protocols),
|
1136 |
* the urgent pointer points to the last octet
|
1137 |
* of urgent data. We continue, however,
|
1138 |
* to consider it to indicate the first octet
|
1139 |
* of data past the urgent section as the original
|
1140 |
* spec states (in one of two places).
|
1141 |
*/
|
1142 |
if (SEQ_GT(ti->ti_seq+ti->ti_urp, tp->rcv_up)) {
|
1143 |
tp->rcv_up = ti->ti_seq + ti->ti_urp; |
1144 |
so->so_urgc = so->so_rcv.sb_cc + |
1145 |
(tp->rcv_up - tp->rcv_nxt); /* -1; */
|
1146 |
tp->rcv_up = ti->ti_seq + ti->ti_urp; |
1147 |
|
1148 |
} |
1149 |
} else
|
1150 |
/*
|
1151 |
* If no out of band data is expected,
|
1152 |
* pull receive urgent pointer along
|
1153 |
* with the receive window.
|
1154 |
*/
|
1155 |
if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
|
1156 |
tp->rcv_up = tp->rcv_nxt; |
1157 |
dodata:
|
1158 |
|
1159 |
/*
|
1160 |
* If this is a small packet, then ACK now - with Nagel
|
1161 |
* congestion avoidance sender won't send more until
|
1162 |
* he gets an ACK.
|
1163 |
*/
|
1164 |
if (ti->ti_len && (unsigned)ti->ti_len <= 5 && |
1165 |
((struct tcpiphdr_2 *)ti)->first_char == (char)27) { |
1166 |
tp->t_flags |= TF_ACKNOW; |
1167 |
} |
1168 |
|
1169 |
/*
|
1170 |
* Process the segment text, merging it into the TCP sequencing queue,
|
1171 |
* and arranging for acknowledgment of receipt if necessary.
|
1172 |
* This process logically involves adjusting tp->rcv_wnd as data
|
1173 |
* is presented to the user (this happens in tcp_usrreq.c,
|
1174 |
* case PRU_RCVD). If a FIN has already been received on this
|
1175 |
* connection then we just ignore the text.
|
1176 |
*/
|
1177 |
if ((ti->ti_len || (tiflags&TH_FIN)) &&
|
1178 |
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
|
1179 |
TCP_REASS(tp, ti, m, so, tiflags); |
1180 |
} else {
|
1181 |
m_free(m); |
1182 |
tiflags &= ~TH_FIN; |
1183 |
} |
1184 |
|
1185 |
/*
|
1186 |
* If FIN is received ACK the FIN and let the user know
|
1187 |
* that the connection is closing.
|
1188 |
*/
|
1189 |
if (tiflags & TH_FIN) {
|
1190 |
if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { |
1191 |
/*
|
1192 |
* If we receive a FIN we can't send more data,
|
1193 |
* set it SS_FDRAIN
|
1194 |
* Shutdown the socket if there is no rx data in the
|
1195 |
* buffer.
|
1196 |
* soread() is called on completion of shutdown() and
|
1197 |
* will got to TCPS_LAST_ACK, and use tcp_output()
|
1198 |
* to send the FIN.
|
1199 |
*/
|
1200 |
sofwdrain(so); |
1201 |
|
1202 |
tp->t_flags |= TF_ACKNOW; |
1203 |
tp->rcv_nxt++; |
1204 |
} |
1205 |
switch (tp->t_state) {
|
1206 |
|
1207 |
/*
|
1208 |
* In SYN_RECEIVED and ESTABLISHED STATES
|
1209 |
* enter the CLOSE_WAIT state.
|
1210 |
*/
|
1211 |
case TCPS_SYN_RECEIVED:
|
1212 |
case TCPS_ESTABLISHED:
|
1213 |
if(so->so_emu == EMU_CTL) /* no shutdown on socket */ |
1214 |
tp->t_state = TCPS_LAST_ACK; |
1215 |
else
|
1216 |
tp->t_state = TCPS_CLOSE_WAIT; |
1217 |
break;
|
1218 |
|
1219 |
/*
|
1220 |
* If still in FIN_WAIT_1 STATE FIN has not been acked so
|
1221 |
* enter the CLOSING state.
|
1222 |
*/
|
1223 |
case TCPS_FIN_WAIT_1:
|
1224 |
tp->t_state = TCPS_CLOSING; |
1225 |
break;
|
1226 |
|
1227 |
/*
|
1228 |
* In FIN_WAIT_2 state enter the TIME_WAIT state,
|
1229 |
* starting the time-wait timer, turning off the other
|
1230 |
* standard timers.
|
1231 |
*/
|
1232 |
case TCPS_FIN_WAIT_2:
|
1233 |
tp->t_state = TCPS_TIME_WAIT; |
1234 |
tcp_canceltimers(tp); |
1235 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
1236 |
break;
|
1237 |
|
1238 |
/*
|
1239 |
* In TIME_WAIT state restart the 2 MSL time_wait timer.
|
1240 |
*/
|
1241 |
case TCPS_TIME_WAIT:
|
1242 |
tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
|
1243 |
break;
|
1244 |
} |
1245 |
} |
1246 |
|
1247 |
/*
|
1248 |
* Return any desired output.
|
1249 |
*/
|
1250 |
if (needoutput || (tp->t_flags & TF_ACKNOW)) {
|
1251 |
(void) tcp_output(tp);
|
1252 |
} |
1253 |
return;
|
1254 |
|
1255 |
dropafterack:
|
1256 |
/*
|
1257 |
* Generate an ACK dropping incoming segment if it occupies
|
1258 |
* sequence space, where the ACK reflects our state.
|
1259 |
*/
|
1260 |
if (tiflags & TH_RST)
|
1261 |
goto drop;
|
1262 |
m_free(m); |
1263 |
tp->t_flags |= TF_ACKNOW; |
1264 |
(void) tcp_output(tp);
|
1265 |
return;
|
1266 |
|
1267 |
dropwithreset:
|
1268 |
/* reuses m if m!=NULL, m_free() unnecessary */
|
1269 |
if (tiflags & TH_ACK)
|
1270 |
tcp_respond(tp, ti, m, (tcp_seq)0, ti->ti_ack, TH_RST);
|
1271 |
else {
|
1272 |
if (tiflags & TH_SYN) ti->ti_len++;
|
1273 |
tcp_respond(tp, ti, m, ti->ti_seq+ti->ti_len, (tcp_seq)0,
|
1274 |
TH_RST|TH_ACK); |
1275 |
} |
1276 |
|
1277 |
return;
|
1278 |
|
1279 |
drop:
|
1280 |
/*
|
1281 |
* Drop space held by incoming segment and return.
|
1282 |
*/
|
1283 |
m_free(m); |
1284 |
} |
1285 |
|
1286 |
static void |
1287 |
tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcpiphdr *ti) |
1288 |
{ |
1289 |
uint16_t mss; |
1290 |
int opt, optlen;
|
1291 |
|
1292 |
DEBUG_CALL("tcp_dooptions");
|
1293 |
DEBUG_ARGS((dfd, " tp = %lx cnt=%i\n", (long)tp, cnt)); |
1294 |
|
1295 |
for (; cnt > 0; cnt -= optlen, cp += optlen) { |
1296 |
opt = cp[0];
|
1297 |
if (opt == TCPOPT_EOL)
|
1298 |
break;
|
1299 |
if (opt == TCPOPT_NOP)
|
1300 |
optlen = 1;
|
1301 |
else {
|
1302 |
optlen = cp[1];
|
1303 |
if (optlen <= 0) |
1304 |
break;
|
1305 |
} |
1306 |
switch (opt) {
|
1307 |
|
1308 |
default:
|
1309 |
continue;
|
1310 |
|
1311 |
case TCPOPT_MAXSEG:
|
1312 |
if (optlen != TCPOLEN_MAXSEG)
|
1313 |
continue;
|
1314 |
if (!(ti->ti_flags & TH_SYN))
|
1315 |
continue;
|
1316 |
memcpy((char *) &mss, (char *) cp + 2, sizeof(mss)); |
1317 |
NTOHS(mss); |
1318 |
(void) tcp_mss(tp, mss); /* sets t_maxseg */ |
1319 |
break;
|
1320 |
} |
1321 |
} |
1322 |
} |
1323 |
|
1324 |
|
1325 |
/*
|
1326 |
* Pull out of band byte out of a segment so
|
1327 |
* it doesn't appear in the user's data queue.
|
1328 |
* It is still reflected in the segment length for
|
1329 |
* sequencing purposes.
|
1330 |
*/
|
1331 |
|
1332 |
#ifdef notdef
|
1333 |
|
1334 |
void
|
1335 |
tcp_pulloutofband(so, ti, m) |
1336 |
struct socket *so;
|
1337 |
struct tcpiphdr *ti;
|
1338 |
register struct mbuf *m; |
1339 |
{ |
1340 |
int cnt = ti->ti_urp - 1; |
1341 |
|
1342 |
while (cnt >= 0) { |
1343 |
if (m->m_len > cnt) {
|
1344 |
char *cp = mtod(m, caddr_t) + cnt;
|
1345 |
struct tcpcb *tp = sototcpcb(so);
|
1346 |
|
1347 |
tp->t_iobc = *cp; |
1348 |
tp->t_oobflags |= TCPOOB_HAVEDATA; |
1349 |
memcpy(sp, cp+1, (unsigned)(m->m_len - cnt - 1)); |
1350 |
m->m_len--; |
1351 |
return;
|
1352 |
} |
1353 |
cnt -= m->m_len; |
1354 |
m = m->m_next; /* XXX WRONG! Fix it! */
|
1355 |
if (m == 0) |
1356 |
break;
|
1357 |
} |
1358 |
panic("tcp_pulloutofband");
|
1359 |
} |
1360 |
|
1361 |
#endif /* notdef */ |
1362 |
|
1363 |
/*
|
1364 |
* Collect new round-trip time estimate
|
1365 |
* and update averages and current timeout.
|
1366 |
*/
|
1367 |
|
1368 |
static void |
1369 |
tcp_xmit_timer(register struct tcpcb *tp, int rtt) |
1370 |
{ |
1371 |
register short delta; |
1372 |
|
1373 |
DEBUG_CALL("tcp_xmit_timer");
|
1374 |
DEBUG_ARG("tp = %lx", (long)tp); |
1375 |
DEBUG_ARG("rtt = %d", rtt);
|
1376 |
|
1377 |
if (tp->t_srtt != 0) { |
1378 |
/*
|
1379 |
* srtt is stored as fixed point with 3 bits after the
|
1380 |
* binary point (i.e., scaled by 8). The following magic
|
1381 |
* is equivalent to the smoothing algorithm in rfc793 with
|
1382 |
* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
|
1383 |
* point). Adjust rtt to origin 0.
|
1384 |
*/
|
1385 |
delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
|
1386 |
if ((tp->t_srtt += delta) <= 0) |
1387 |
tp->t_srtt = 1;
|
1388 |
/*
|
1389 |
* We accumulate a smoothed rtt variance (actually, a
|
1390 |
* smoothed mean difference), then set the retransmit
|
1391 |
* timer to smoothed rtt + 4 times the smoothed variance.
|
1392 |
* rttvar is stored as fixed point with 2 bits after the
|
1393 |
* binary point (scaled by 4). The following is
|
1394 |
* equivalent to rfc793 smoothing with an alpha of .75
|
1395 |
* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
|
1396 |
* rfc793's wired-in beta.
|
1397 |
*/
|
1398 |
if (delta < 0) |
1399 |
delta = -delta; |
1400 |
delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); |
1401 |
if ((tp->t_rttvar += delta) <= 0) |
1402 |
tp->t_rttvar = 1;
|
1403 |
} else {
|
1404 |
/*
|
1405 |
* No rtt measurement yet - use the unsmoothed rtt.
|
1406 |
* Set the variance to half the rtt (so our first
|
1407 |
* retransmit happens at 3*rtt).
|
1408 |
*/
|
1409 |
tp->t_srtt = rtt << TCP_RTT_SHIFT; |
1410 |
tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
|
1411 |
} |
1412 |
tp->t_rtt = 0;
|
1413 |
tp->t_rxtshift = 0;
|
1414 |
|
1415 |
/*
|
1416 |
* the retransmit should happen at rtt + 4 * rttvar.
|
1417 |
* Because of the way we do the smoothing, srtt and rttvar
|
1418 |
* will each average +1/2 tick of bias. When we compute
|
1419 |
* the retransmit timer, we want 1/2 tick of rounding and
|
1420 |
* 1 extra tick because of +-1/2 tick uncertainty in the
|
1421 |
* firing of the timer. The bias will give us exactly the
|
1422 |
* 1.5 tick we need. But, because the bias is
|
1423 |
* statistical, we have to test that we don't drop below
|
1424 |
* the minimum feasible timer (which is 2 ticks).
|
1425 |
*/
|
1426 |
TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), |
1427 |
(short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */ |
1428 |
|
1429 |
/*
|
1430 |
* We received an ack for a packet that wasn't retransmitted;
|
1431 |
* it is probably safe to discard any error indications we've
|
1432 |
* received recently. This isn't quite right, but close enough
|
1433 |
* for now (a route might have failed after we sent a segment,
|
1434 |
* and the return path might not be symmetrical).
|
1435 |
*/
|
1436 |
tp->t_softerror = 0;
|
1437 |
} |
1438 |
|
1439 |
/*
|
1440 |
* Determine a reasonable value for maxseg size.
|
1441 |
* If the route is known, check route for mtu.
|
1442 |
* If none, use an mss that can be handled on the outgoing
|
1443 |
* interface without forcing IP to fragment; if bigger than
|
1444 |
* an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
|
1445 |
* to utilize large mbufs. If no route is found, route has no mtu,
|
1446 |
* or the destination isn't local, use a default, hopefully conservative
|
1447 |
* size (usually 512 or the default IP max size, but no more than the mtu
|
1448 |
* of the interface), as we can't discover anything about intervening
|
1449 |
* gateways or networks. We also initialize the congestion/slow start
|
1450 |
* window to be a single segment if the destination isn't local.
|
1451 |
* While looking at the routing entry, we also initialize other path-dependent
|
1452 |
* parameters from pre-set or cached values in the routing entry.
|
1453 |
*/
|
1454 |
|
1455 |
int
|
1456 |
tcp_mss(struct tcpcb *tp, u_int offer)
|
1457 |
{ |
1458 |
struct socket *so = tp->t_socket;
|
1459 |
int mss;
|
1460 |
|
1461 |
DEBUG_CALL("tcp_mss");
|
1462 |
DEBUG_ARG("tp = %lx", (long)tp); |
1463 |
DEBUG_ARG("offer = %d", offer);
|
1464 |
|
1465 |
mss = min(IF_MTU, IF_MRU) - sizeof(struct tcpiphdr); |
1466 |
if (offer)
|
1467 |
mss = min(mss, offer); |
1468 |
mss = max(mss, 32);
|
1469 |
if (mss < tp->t_maxseg || offer != 0) |
1470 |
tp->t_maxseg = mss; |
1471 |
|
1472 |
tp->snd_cwnd = mss; |
1473 |
|
1474 |
sbreserve(&so->so_snd, TCP_SNDSPACE + ((TCP_SNDSPACE % mss) ? |
1475 |
(mss - (TCP_SNDSPACE % mss)) : |
1476 |
0));
|
1477 |
sbreserve(&so->so_rcv, TCP_RCVSPACE + ((TCP_RCVSPACE % mss) ? |
1478 |
(mss - (TCP_RCVSPACE % mss)) : |
1479 |
0));
|
1480 |
|
1481 |
DEBUG_MISC((dfd, " returning mss = %d\n", mss));
|
1482 |
|
1483 |
return mss;
|
1484 |
} |