freebsd-skq/sys/netinet/tcp_timewait.c
Poul-Henning Kamp 19ddafa3b3 RFC 1644 has the status "Experimental Protocol", which means:
4.1.4.  Experimental Protocol

      A system should not implement an experimental protocol unless it
      is participating in the experiment and has coordinated its use of
      the protocol with the developer of the protocol.

Pointed out by:	Steinar Haug <sthaug@nethelp.no>
1998-09-06 08:17:35 +00:00

752 lines
20 KiB
C

/*
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95
* $Id: tcp_subr.c,v 1.46 1998/08/24 07:47:39 dfr Exp $
*/
#include "opt_compat.h"
#include "opt_tcpdebug.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <vm/vm_zone.h>
#include <net/route.h>
#include <net/if.h>
#define _IP_VHL
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#ifdef TCPDEBUG
#include <netinet/tcp_debug.h>
#endif
int tcp_mssdflt = TCP_MSS;
SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
CTLFLAG_RW, &tcp_mssdflt , 0, "");
static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt,
CTLFLAG_RW, &tcp_rttdflt , 0, "");
static int tcp_do_rfc1323 = 1;
SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323,
CTLFLAG_RW, &tcp_do_rfc1323 , 0, "");
static int tcp_do_rfc1644 = 0;
SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644,
CTLFLAG_RW, &tcp_do_rfc1644 , 0, "");
SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, &tcbinfo.ipi_count,
0, "Number of active PCBs");
static void tcp_cleartaocache __P((void));
static void tcp_notify __P((struct inpcb *, int));
/*
* Target size of TCP PCB hash tables. Must be a power of two.
*/
#ifndef TCBHASHSIZE
#define TCBHASHSIZE 512
#endif
/*
* This is the actual shape of what we allocate using the zone
* allocator. Doing it this way allows us to protect both structures
* using the same generation count, and also eliminates the overhead
* of allocating tcpcbs separately. By hiding the structure here,
* we avoid changing most of the rest of the code (although it needs
* to be changed, eventually, for greater efficiency).
*/
#define ALIGNMENT 32
#define ALIGNM1 (ALIGNMENT - 1)
struct inp_tp {
union {
struct inpcb inp;
char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1];
} inp_tp_u;
struct tcpcb tcb;
};
#undef ALIGNMENT
#undef ALIGNM1
/*
* Tcp initialization
*/
void
tcp_init()
{
tcp_iss = random(); /* wrong, but better than a constant */
tcp_ccgen = 1;
tcp_cleartaocache();
LIST_INIT(&tcb);
tcbinfo.listhead = &tcb;
tcbinfo.hashbase = hashinit(TCBHASHSIZE, M_PCB, &tcbinfo.hashmask);
tcbinfo.porthashbase = hashinit(TCBHASHSIZE, M_PCB,
&tcbinfo.porthashmask);
tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets,
ZONE_INTERRUPT, 0);
if (max_protohdr < sizeof(struct tcpiphdr))
max_protohdr = sizeof(struct tcpiphdr);
if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN)
panic("tcp_init");
}
/*
* Create template to be used to send tcp packets on a connection.
* Call after host entry created, allocates an mbuf and fills
* in a skeletal tcp/ip header, minimizing the amount of work
* necessary when the connection is used.
*/
struct tcpiphdr *
tcp_template(tp)
struct tcpcb *tp;
{
register struct inpcb *inp = tp->t_inpcb;
register struct mbuf *m;
register struct tcpiphdr *n;
if ((n = tp->t_template) == 0) {
m = m_get(M_DONTWAIT, MT_HEADER);
if (m == NULL)
return (0);
m->m_len = sizeof (struct tcpiphdr);
n = mtod(m, struct tcpiphdr *);
}
bzero(n->ti_x1, sizeof(n->ti_x1));
n->ti_pr = IPPROTO_TCP;
n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));
n->ti_src = inp->inp_laddr;
n->ti_dst = inp->inp_faddr;
n->ti_sport = inp->inp_lport;
n->ti_dport = inp->inp_fport;
n->ti_seq = 0;
n->ti_ack = 0;
n->ti_x2 = 0;
n->ti_off = 5;
n->ti_flags = 0;
n->ti_win = 0;
n->ti_sum = 0;
n->ti_urp = 0;
return (n);
}
/*
* Send a single message to the TCP at address specified by
* the given TCP/IP header. If m == 0, then we make a copy
* of the tcpiphdr at ti and send directly to the addressed host.
* This is used to force keep alive messages out using the TCP
* template for a connection tp->t_template. If flags are given
* then we send a message back to the TCP which originated the
* segment ti, and discard the mbuf containing it and any other
* attached mbufs.
*
* In any case the ack and sequence number of the transmitted
* segment are as specified by the parameters.
*
* NOTE: If m != NULL, then ti must point to *inside* the mbuf.
*/
void
tcp_respond(tp, ti, m, ack, seq, flags)
struct tcpcb *tp;
register struct tcpiphdr *ti;
register struct mbuf *m;
tcp_seq ack, seq;
int flags;
{
register int tlen;
int win = 0;
struct route *ro = 0;
struct route sro;
if (tp) {
win = sbspace(&tp->t_inpcb->inp_socket->so_rcv);
ro = &tp->t_inpcb->inp_route;
} else {
ro = &sro;
bzero(ro, sizeof *ro);
}
if (m == 0) {
m = m_gethdr(M_DONTWAIT, MT_HEADER);
if (m == NULL)
return;
#ifdef TCP_COMPAT_42
tlen = 1;
#else
tlen = 0;
#endif
m->m_data += max_linkhdr;
*mtod(m, struct tcpiphdr *) = *ti;
ti = mtod(m, struct tcpiphdr *);
flags = TH_ACK;
} else {
m_freem(m->m_next);
m->m_next = 0;
m->m_data = (caddr_t)ti;
m->m_len = sizeof (struct tcpiphdr);
tlen = 0;
#define xchg(a,b,type) { type t; t=a; a=b; b=t; }
xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, n_long);
xchg(ti->ti_dport, ti->ti_sport, n_short);
#undef xchg
}
ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));
tlen += sizeof (struct tcpiphdr);
m->m_len = tlen;
m->m_pkthdr.len = tlen;
m->m_pkthdr.rcvif = (struct ifnet *) 0;
bzero(ti->ti_x1, sizeof(ti->ti_x1));
ti->ti_seq = htonl(seq);
ti->ti_ack = htonl(ack);
ti->ti_x2 = 0;
ti->ti_off = sizeof (struct tcphdr) >> 2;
ti->ti_flags = flags;
if (tp)
ti->ti_win = htons((u_short) (win >> tp->rcv_scale));
else
ti->ti_win = htons((u_short)win);
ti->ti_urp = 0;
ti->ti_sum = 0;
ti->ti_sum = in_cksum(m, tlen);
((struct ip *)ti)->ip_len = tlen;
((struct ip *)ti)->ip_ttl = ip_defttl;
#ifdef TCPDEBUG
if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
tcp_trace(TA_OUTPUT, 0, tp, ti, 0);
#endif
(void) ip_output(m, NULL, ro, 0, NULL);
if (ro == &sro && ro->ro_rt) {
RTFREE(ro->ro_rt);
}
}
/*
* Create a new TCP control block, making an
* empty reassembly queue and hooking it to the argument
* protocol control block. The `inp' parameter must have
* come from the zone allocator set up in tcp_init().
*/
struct tcpcb *
tcp_newtcpcb(inp)
struct inpcb *inp;
{
struct inp_tp *it;
register struct tcpcb *tp;
it = (struct inp_tp *)inp;
tp = &it->tcb;
bzero((char *) tp, sizeof(struct tcpcb));
tp->t_segq = NULL;
tp->t_maxseg = tp->t_maxopd = tcp_mssdflt;
if (tcp_do_rfc1323)
tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
if (tcp_do_rfc1644)
tp->t_flags |= TF_REQ_CC;
tp->t_inpcb = inp; /* XXX */
/*
* Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
* rtt estimate. Set rttvar so that srtt + 4 * rttvar gives
* reasonable initial retransmit time.
*/
tp->t_srtt = TCPTV_SRTTBASE;
tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
tp->t_rttmin = TCPTV_MIN;
tp->t_rxtcur = TCPTV_RTOBASE;
tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
inp->inp_ip_ttl = ip_defttl;
inp->inp_ppcb = (caddr_t)tp;
return (tp); /* XXX */
}
/*
* Drop a TCP connection, reporting
* the specified error. If connection is synchronized,
* then send a RST to peer.
*/
struct tcpcb *
tcp_drop(tp, errno)
register struct tcpcb *tp;
int errno;
{
struct socket *so = tp->t_inpcb->inp_socket;
if (TCPS_HAVERCVDSYN(tp->t_state)) {
tp->t_state = TCPS_CLOSED;
(void) tcp_output(tp);
tcpstat.tcps_drops++;
} else
tcpstat.tcps_conndrops++;
if (errno == ETIMEDOUT && tp->t_softerror)
errno = tp->t_softerror;
so->so_error = errno;
return (tcp_close(tp));
}
/*
* Close a TCP control block:
* discard all space held by the tcp
* discard internet protocol block
* wake up any sleepers
*/
struct tcpcb *
tcp_close(tp)
register struct tcpcb *tp;
{
register struct mbuf *q;
register struct mbuf *nq;
struct inpcb *inp = tp->t_inpcb;
struct socket *so = inp->inp_socket;
register struct mbuf *m;
register struct rtentry *rt;
int dosavessthresh;
/*
* If we got enough samples through the srtt filter,
* save the rtt and rttvar in the routing entry.
* 'Enough' is arbitrarily defined as the 16 samples.
* 16 samples is enough for the srtt filter to converge
* to within 5% of the correct value; fewer samples and
* we could save a very bogus rtt.
*
* Don't update the default route's characteristics and don't
* update anything that the user "locked".
*/
if (tp->t_rttupdated >= 16 &&
(rt = inp->inp_route.ro_rt) &&
((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) {
register u_long i = 0;
if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) {
i = tp->t_srtt *
(RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE));
if (rt->rt_rmx.rmx_rtt && i)
/*
* filter this update to half the old & half
* the new values, converting scale.
* See route.h and tcp_var.h for a
* description of the scaling constants.
*/
rt->rt_rmx.rmx_rtt =
(rt->rt_rmx.rmx_rtt + i) / 2;
else
rt->rt_rmx.rmx_rtt = i;
tcpstat.tcps_cachedrtt++;
}
if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) {
i = tp->t_rttvar *
(RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE));
if (rt->rt_rmx.rmx_rttvar && i)
rt->rt_rmx.rmx_rttvar =
(rt->rt_rmx.rmx_rttvar + i) / 2;
else
rt->rt_rmx.rmx_rttvar = i;
tcpstat.tcps_cachedrttvar++;
}
/*
* The old comment here said:
* update the pipelimit (ssthresh) if it has been updated
* already or if a pipesize was specified & the threshhold
* got below half the pipesize. I.e., wait for bad news
* before we start updating, then update on both good
* and bad news.
*
* But we want to save the ssthresh even if no pipesize is
* specified explicitly in the route, because such
* connections still have an implicit pipesize specified
* by the global tcp_sendspace. In the absence of a reliable
* way to calculate the pipesize, it will have to do.
*/
i = tp->snd_ssthresh;
if (rt->rt_rmx.rmx_sendpipe != 0)
dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2);
else
dosavessthresh = (i < so->so_snd.sb_hiwat / 2);
if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 &&
i != 0 && rt->rt_rmx.rmx_ssthresh != 0)
|| dosavessthresh) {
/*
* convert the limit from user data bytes to
* packets then to packet data bytes.
*/
i = (i + tp->t_maxseg / 2) / tp->t_maxseg;
if (i < 2)
i = 2;
i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr));
if (rt->rt_rmx.rmx_ssthresh)
rt->rt_rmx.rmx_ssthresh =
(rt->rt_rmx.rmx_ssthresh + i) / 2;
else
rt->rt_rmx.rmx_ssthresh = i;
tcpstat.tcps_cachedssthresh++;
}
}
/* free the reassembly queue, if any */
for (q = tp->t_segq; q; q = nq) {
nq = q->m_nextpkt;
tp->t_segq = nq;
m_freem(q);
}
if (tp->t_template)
(void) m_free(dtom(tp->t_template));
inp->inp_ppcb = NULL;
soisdisconnected(so);
in_pcbdetach(inp);
tcpstat.tcps_closed++;
return ((struct tcpcb *)0);
}
void
tcp_drain()
{
}
/*
* Notify a tcp user of an asynchronous error;
* store error as soft error, but wake up user
* (for now, won't do anything until can select for soft error).
*/
static void
tcp_notify(inp, error)
struct inpcb *inp;
int error;
{
register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb;
register struct socket *so = inp->inp_socket;
/*
* Ignore some errors if we are hooked up.
* If connection hasn't completed, has retransmitted several times,
* and receives a second error, give up now. This is better
* than waiting a long time to establish a connection that
* can never complete.
*/
if (tp->t_state == TCPS_ESTABLISHED &&
(error == EHOSTUNREACH || error == ENETUNREACH ||
error == EHOSTDOWN)) {
return;
} else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
tp->t_softerror)
so->so_error = error;
else
tp->t_softerror = error;
wakeup((caddr_t) &so->so_timeo);
sorwakeup(so);
sowwakeup(so);
}
static int
tcp_pcblist SYSCTL_HANDLER_ARGS
{
int error, i, n, s;
struct inpcb *inp, **inp_list;
inp_gen_t gencnt;
struct xinpgen xig;
/*
* The process of preparing the TCB list is too time-consuming and
* resource-intensive to repeat twice on every request.
*/
if (req->oldptr == 0) {
n = tcbinfo.ipi_count;
req->oldidx = 2 * (sizeof xig)
+ (n + n/8) * sizeof(struct xtcpcb);
return 0;
}
if (req->newptr != 0)
return EPERM;
/*
* OK, now we're committed to doing something.
*/
s = splnet();
gencnt = tcbinfo.ipi_gencnt;
n = tcbinfo.ipi_count;
splx(s);
xig.xig_len = sizeof xig;
xig.xig_count = n;
xig.xig_gen = gencnt;
xig.xig_sogen = so_gencnt;
error = SYSCTL_OUT(req, &xig, sizeof xig);
if (error)
return error;
inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
if (inp_list == 0)
return ENOMEM;
s = splnet();
for (inp = tcbinfo.listhead->lh_first, i = 0; inp && i < n;
inp = inp->inp_list.le_next) {
if (inp->inp_gencnt <= gencnt)
inp_list[i++] = inp;
}
splx(s);
n = i;
error = 0;
for (i = 0; i < n; i++) {
inp = inp_list[i];
if (inp->inp_gencnt <= gencnt) {
struct xtcpcb xt;
xt.xt_len = sizeof xt;
/* XXX should avoid extra copy */
bcopy(inp, &xt.xt_inp, sizeof *inp);
bcopy(inp->inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
if (inp->inp_socket)
sotoxsocket(inp->inp_socket, &xt.xt_socket);
error = SYSCTL_OUT(req, &xt, sizeof xt);
}
}
if (!error) {
/*
* Give the user an updated idea of our state.
* If the generation differs from what we told
* her before, she knows that something happened
* while we were processing this request, and it
* might be necessary to retry.
*/
s = splnet();
xig.xig_gen = tcbinfo.ipi_gencnt;
xig.xig_sogen = so_gencnt;
xig.xig_count = tcbinfo.ipi_count;
splx(s);
error = SYSCTL_OUT(req, &xig, sizeof xig);
}
free(inp_list, M_TEMP);
return error;
}
SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0,
tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
void
tcp_ctlinput(cmd, sa, vip)
int cmd;
struct sockaddr *sa;
void *vip;
{
register struct ip *ip = vip;
register struct tcphdr *th;
void (*notify) __P((struct inpcb *, int)) = tcp_notify;
if (cmd == PRC_QUENCH)
notify = tcp_quench;
else if (cmd == PRC_MSGSIZE)
notify = tcp_mtudisc;
else if (!PRC_IS_REDIRECT(cmd) &&
((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0))
return;
if (ip) {
th = (struct tcphdr *)((caddr_t)ip
+ (IP_VHL_HL(ip->ip_vhl) << 2));
in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport,
cmd, notify);
} else
in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify);
}
/*
* When a source quench is received, close congestion window
* to one segment. We will gradually open it again as we proceed.
*/
void
tcp_quench(inp, errno)
struct inpcb *inp;
int errno;
{
struct tcpcb *tp = intotcpcb(inp);
if (tp)
tp->snd_cwnd = tp->t_maxseg;
}
/*
* When `need fragmentation' ICMP is received, update our idea of the MSS
* based on the new value in the route. Also nudge TCP to send something,
* since we know the packet we just sent was dropped.
* This duplicates some code in the tcp_mss() function in tcp_input.c.
*/
void
tcp_mtudisc(inp, errno)
struct inpcb *inp;
int errno;
{
struct tcpcb *tp = intotcpcb(inp);
struct rtentry *rt;
struct rmxp_tao *taop;
struct socket *so = inp->inp_socket;
int offered;
int mss;
if (tp) {
rt = tcp_rtlookup(inp);
if (!rt || !rt->rt_rmx.rmx_mtu) {
tp->t_maxopd = tp->t_maxseg = tcp_mssdflt;
return;
}
taop = rmx_taop(rt->rt_rmx);
offered = taop->tao_mssopt;
mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr);
if (offered)
mss = min(mss, offered);
/*
* XXX - The above conditional probably violates the TCP
* spec. The problem is that, since we don't know the
* other end's MSS, we are supposed to use a conservative
* default. But, if we do that, then MTU discovery will
* never actually take place, because the conservative
* default is much less than the MTUs typically seen
* on the Internet today. For the moment, we'll sweep
* this under the carpet.
*
* The conservative default might not actually be a problem
* if the only case this occurs is when sending an initial
* SYN with options and data to a host we've never talked
* to before. Then, they will reply with an MSS value which
* will get recorded and the new parameters should get
* recomputed. For Further Study.
*/
if (tp->t_maxopd <= mss)
return;
tp->t_maxopd = mss;
if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
(tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)
mss -= TCPOLEN_TSTAMP_APPA;
if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC &&
(tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)
mss -= TCPOLEN_CC_APPA;
#if (MCLBYTES & (MCLBYTES - 1)) == 0
if (mss > MCLBYTES)
mss &= ~(MCLBYTES-1);
#else
if (mss > MCLBYTES)
mss = mss / MCLBYTES * MCLBYTES;
#endif
if (so->so_snd.sb_hiwat < mss)
mss = so->so_snd.sb_hiwat;
tp->t_maxseg = mss;
tcpstat.tcps_mturesent++;
tp->t_rtt = 0;
tp->snd_nxt = tp->snd_una;
tcp_output(tp);
}
}
/*
* Look-up the routing entry to the peer of this inpcb. If no route
* is found and it cannot be allocated the return NULL. This routine
* is called by TCP routines that access the rmx structure and by tcp_mss
* to get the interface MTU.
*/
struct rtentry *
tcp_rtlookup(inp)
struct inpcb *inp;
{
struct route *ro;
struct rtentry *rt;
ro = &inp->inp_route;
rt = ro->ro_rt;
if (rt == NULL || !(rt->rt_flags & RTF_UP)) {
/* No route yet, so try to acquire one */
if (inp->inp_faddr.s_addr != INADDR_ANY) {
ro->ro_dst.sa_family = AF_INET;
ro->ro_dst.sa_len = sizeof(ro->ro_dst);
((struct sockaddr_in *) &ro->ro_dst)->sin_addr =
inp->inp_faddr;
rtalloc(ro);
rt = ro->ro_rt;
}
}
return rt;
}
/*
* Return a pointer to the cached information about the remote host.
* The cached information is stored in the protocol specific part of
* the route metrics.
*/
struct rmxp_tao *
tcp_gettaocache(inp)
struct inpcb *inp;
{
struct rtentry *rt = tcp_rtlookup(inp);
/* Make sure this is a host route and is up. */
if (rt == NULL ||
(rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST))
return NULL;
return rmx_taop(rt->rt_rmx);
}
/*
* Clear all the TAO cache entries, called from tcp_init.
*
* XXX
* This routine is just an empty one, because we assume that the routing
* routing tables are initialized at the same time when TCP, so there is
* nothing in the cache left over.
*/
static void
tcp_cleartaocache()
{
}