src/parsec/disk-image/parsec/parsec-benchmark/pkgs/libs/uptcpip/src/freebsd.netinet/tcp_timewait.c - public/gem5-resources - Git at Google

 /*-
  * 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.
  * 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
  */

 #include <sys/bsd_cdefs.h>
 //__FBSDID("$FreeBSD$");

 #include "bsd_opt_inet.h"
 #include "bsd_opt_inet6.h"
 #include "bsd_opt_tcpdebug.h"

 #include <sys/bsd_param.h>
 #include <sys/bsd_systm.h>
 #include <sys/bsd_callout.h>
 #include <sys/bsd_kernel.h>
 //baoyg//#include <sys/bsd_sysctl.h>
 #include <sys/bsd_malloc.h>
 #include <sys/bsd_mbuf.h>
 //#include <sys/bsd_priv.h>
 ////#include <sys/bsd_proc.h>
 #include <sys/bsd_socket.h>
 #include <sys/bsd_socketvar.h>
 #include <sys/bsd_protosw.h>
 #include <sys/bsd_random.h>

 #include <vm/bsd_uma.h>

 #include <net/bsd_route.h>
 #include <net/bsd_if.h>
 #include <net/bsd_vnet.h>

 #include <netinet/bsd_in.h>
 #include <netinet/bsd_in_systm.h>
 #include <netinet/bsd_ip.h>
 #ifdef INET6
 #include <netinet/bsd_ip6.h>
 #endif
 #include <netinet/bsd_in_pcb.h>
 #ifdef INET6
 #include <netinet6/bsd_in6_pcb.h>
 #endif
 #include <netinet/bsd_in_var.h>
 #include <netinet/bsd_ip_var.h>
 #ifdef INET6
 #include <netinet6/bsd_ip6_var.h>
 #include <netinet6/bsd_scope6_var.h>
 #include <netinet6/bsd_nd6.h>
 #endif
 #include <netinet/bsd_ip_icmp.h>
 #include <netinet/bsd_tcp.h>
 #include <netinet/bsd_tcp_fsm.h>
 #include <netinet/bsd_tcp_seq.h>
 #include <netinet/bsd_tcp_timer.h>
 #include <netinet/bsd_tcp_var.h>
 #ifdef INET6
 #include <netinet6/bsd_tcp6_var.h>
 #endif
 #include <netinet/bsd_tcpip.h>
 #ifdef TCPDEBUG
 #include <netinet/bsd_tcp_debug.h>
 #endif
 #include <netinet6/bsd_ip6protosw.h>

 #include <machine/bsd_in_cksum.h>

 #ifdef MAC
 #include <security/mac/bsd_mac_framework.h>
 #endif

 extern int bsd_ticks;
 static int	maxtcptw;

 /*
  * The timed wait queue contains references to each of the TCP sessions
  * currently in the TIME_WAIT state.  The queue pointers, including the
  * queue pointers in each tcptw structure, are protected using the global
  * tcbinfo lock, which must be held over queue iteration and modification.
  */
 static VNET_DEFINE(uma_zone_t, tcptw_zone);
 static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl);
 VNET_DEFINE(int, nolocaltimewait);

 #define	V_tcptw_zone			VNET(tcptw_zone)
 #define	V_twq_2msl			VNET(twq_2msl)

 static void	tcp_tw_2msl_reset(struct tcptw *, int);
 static void	tcp_tw_2msl_stop(struct tcptw *);

 static int
 tcptw_auto_size(void)
 {
 	int halfrange;

 	/*
 	 * Max out at half the ephemeral port range so that TIME_WAIT
 	 * sockets don't tie up too many ephemeral ports.
 	 */
 	if (V_ipport_lastauto > V_ipport_firstauto)
 		halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2;
 	else
 		halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2;
 	/* Protect against goofy port ranges smaller than 32. */
 	return (imin(imax(halfrange, 32), maxsockets / 5));
 }
 /*
 static int
 sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)
 {
 	int error, new;

 	if (maxtcptw == 0)
 		new = tcptw_auto_size();
 	else
 		new = maxtcptw;
 	error = sysctl_handle_int(oidp, &new, 0, req);
 	if (error == 0 && req->newptr)
 		if (new >= 32) {
 			maxtcptw = new;
 			uma_zone_set_max(V_tcptw_zone, maxtcptw);
 		}
 	return (error);
 }

 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW,
     &maxtcptw, 0, sysctl_maxtcptw, "IU",
     "Maximum number of compressed TCP TIME_WAIT entries");

 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW,
     &VNET_NAME(nolocaltimewait), 0,
     "Do not create compressed TCP TIME_WAIT entries for local connections");
 */
 void
 tcp_tw_zone_change(void)
 {

 	if (maxtcptw == 0)
 		uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
 }

 void
 tcp_tw_init(void)
 {

 	V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 	//TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
 	if (maxtcptw == 0)
 		uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
 	else
 		uma_zone_set_max(V_tcptw_zone, maxtcptw);
 	TAILQ_INIT(&V_twq_2msl);
 }

 #ifdef VIMAGE
 void
 tcp_tw_destroy(void)
 {
 	struct tcptw *tw;

 	INP_INFO_WLOCK(&V_tcbinfo);
 	while((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
 		tcp_twclose(tw, 0);
 	INP_INFO_WUNLOCK(&V_tcbinfo);
 }
 #endif

 /*
  * Move a TCP connection into TIME_WAIT state.
  *    tcbinfo is locked.
  *    inp is locked, and is unlocked before returning.
  */
 void
 tcp_twstart(struct tcpcb *tp)
 {
 	struct tcptw *tw;
 	struct inpcb *inp = tp->t_inpcb;
 	int acknow;
 	struct socket *so;

 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);	/* tcp_tw_2msl_reset(). */
 	INP_WLOCK_ASSERT(inp);

 	if (V_nolocaltimewait && in_localip(inp->inp_faddr)) {
 		tp = tcp_close(tp);
 		if (tp != NULL)
 			INP_WUNLOCK(inp);
 		return;
 	}

 	tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
 	if (tw == NULL) {
 		tw = tcp_tw_2msl_scan(1);
 		if (tw == NULL) {
 			tp = tcp_close(tp);
 			if (tp != NULL)
 				INP_WUNLOCK(inp);
 			return;
 		}
 	}
 	tw->tw_inpcb = inp;

 	/*
 	 * Recover last window size sent.
 	 */
 	tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;

 	/*
 	 * Set t_recent if timestamps are used on the connection.
 	 */
 	if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) ==
 	    (TF_REQ_TSTMP|TF_RCVD_TSTMP)) {
 		tw->t_recent = tp->ts_recent;
 		tw->ts_offset = tp->ts_offset;
 	} else {
 		tw->t_recent = 0;
 		tw->ts_offset = 0;
 	}

 	tw->snd_nxt = tp->snd_nxt;
 	tw->rcv_nxt = tp->rcv_nxt;
 	tw->iss     = tp->iss;
 	tw->irs     = tp->irs;
 	tw->t_starttime = tp->t_starttime;
 	tw->tw_time = 0;

 /* XXX
  * If this code will
  * be used for fin-wait-2 state also, then we may need
  * a ts_recent from the last segment.
  */
 	acknow = tp->t_flags & TF_ACKNOW;

 	/*
 	 * First, discard tcpcb state, which includes stopping its timers and
 	 * freeing it.  tcp_discardcb() used to also release the inpcb, but
 	 * that work is now done in the caller.
 	 *
 	 * Note: soisdisconnected() call used to be made in tcp_discardcb(),
 	 * and might not be needed here any longer.
 	 */
 	tcp_discardcb(tp);
 	so = inp->inp_socket;
 	soisdisconnected(so);
 	tw->tw_cred = NULL;//crhold(so->so_cred);
 	SOCK_LOCK(so);
 	tw->tw_so_options = so->so_options;
 	SOCK_UNLOCK(so);
 	if (acknow)
 		tcp_twrespond(tw, TH_ACK);
 	inp->inp_ppcb = tw;
 	inp->inp_flags |= INP_TIMEWAIT;
 	tcp_tw_2msl_reset(tw, 0);

 	/*
 	 * If the inpcb owns the sole reference to the socket, then we can
 	 * detach and free the socket as it is not needed in time wait.
 	 */
 	if (inp->inp_flags & INP_SOCKREF) {
 		KASSERT(so->so_state & SS_PROTOREF,
 		    ("tcp_twstart: !SS_PROTOREF"));
 		inp->inp_flags &= ~INP_SOCKREF;
 		INP_WUNLOCK(inp);
 		ACCEPT_LOCK();
 		SOCK_LOCK(so);
 		so->so_state &= ~SS_PROTOREF;
 		sofree(so);
 	} else
 		INP_WUNLOCK(inp);
 }

 #if 0
 /*
  * The appromixate rate of ISN increase of Microsoft TCP stacks;
  * the actual rate is slightly higher due to the addition of
  * random positive increments.
  *
  * Most other new OSes use semi-randomized ISN values, so we
  * do not need to worry about them.
  */
 #define MS_ISN_BYTES_PER_SECOND		250000

 /*
  * Determine if the ISN we will generate has advanced beyond the last
  * sequence number used by the previous connection.  If so, indicate
  * that it is safe to recycle this tw socket by returning 1.
  */
 int
 tcp_twrecycleable(struct tcptw *tw)
 {
 	tcp_seq new_iss = tw->iss;
 	tcp_seq new_irs = tw->irs;

 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 	new_iss += (bsd_ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz);
 	new_irs += (bsd_ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz);

 	if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt))
 		return (1);
 	else
 		return (0);
 }
 #endif

 /*
  * Returns 1 if the TIME_WAIT state was killed and we should start over,
  * looking for a pcb in the listen state.  Returns 0 otherwise.
  */
 int
 tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
     struct mbuf *m, int tlen)
 {
 	struct tcptw *tw;
 	int thflags;
 	tcp_seq seq;

 	/* tcbinfo lock required for tcp_twclose(), tcp_tw_2msl_reset(). */
 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 	INP_WLOCK_ASSERT(inp);

 	/*
 	 * XXXRW: Time wait state for inpcb has been recycled, but inpcb is
 	 * still present.  This is undesirable, but temporarily necessary
 	 * until we work out how to handle inpcb's who's timewait state has
 	 * been removed.
 	 */
 	tw = intotw(inp);
 	if (tw == NULL)
 		goto drop;

 	thflags = th->th_flags;

 	/*
 	 * NOTE: for FIN_WAIT_2 (to be added later),
 	 * must validate sequence number before accepting RST
 	 */

 	/*
 	 * If the segment contains RST:
 	 *	Drop the segment - see Stevens, vol. 2, p. 964 and
 	 *      RFC 1337.
 	 */
 	if (thflags & TH_RST)
 		goto drop;

 #if 0
 /* PAWS not needed at the moment */
 	/*
 	 * RFC 1323 PAWS: If we have a timestamp reply on this segment
 	 * and it's less than ts_recent, drop it.
 	 */
 	if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
 	    TSTMP_LT(to.to_tsval, tp->ts_recent)) {
 		if ((thflags & TH_ACK) == 0)
 			goto drop;
 		goto ack;
 	}
 	/*
 	 * ts_recent is never updated because we never accept new segments.
 	 */
 #endif

 	/*
 	 * If a new connection request is received
 	 * while in TIME_WAIT, drop the old connection
 	 * and start over if the sequence numbers
 	 * are above the previous ones.
 	 */
 	if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
 		tcp_twclose(tw, 0);
 		return (1);
 	}

 	/*
 	 * Drop the the segment if it does not contain an ACK.
 	 */
 	if ((thflags & TH_ACK) == 0)
 		goto drop;

 	/*
 	 * Reset the 2MSL timer if this is a duplicate FIN.
 	 */
 	if (thflags & TH_FIN) {
 		seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
 		if (seq + 1 == tw->rcv_nxt)
 			tcp_tw_2msl_reset(tw, 1);
 	}

 	/*
 	 * Acknowledge the segment if it has data or is not a duplicate ACK.
 	 */
 	if (thflags != TH_ACK || tlen != 0 ||
 	    th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt)
 		tcp_twrespond(tw, TH_ACK);
 drop:
 	INP_WUNLOCK(inp);
 	m_freem(m);
 	return (0);
 }

 void
 tcp_twclose(struct tcptw *tw, int reuse)
 {
 	struct socket *so;
 	struct inpcb *inp;

 	/*
 	 * At this point, we are in one of two situations:
 	 *
 	 * (1) We have no socket, just an inpcb<->twtcp pair.  We can free
 	 *     all state.
 	 *
 	 * (2) We have a socket -- if we own a reference, release it and
 	 *     notify the socket layer.
 	 */
 	inp = tw->tw_inpcb;
 	KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
 	KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);	/* tcp_tw_2msl_stop(). */
 	INP_WLOCK_ASSERT(inp);

 	tw->tw_inpcb = NULL;
 	tcp_tw_2msl_stop(tw);
 	inp->inp_ppcb = NULL;
 	in_pcbdrop(inp);

 	so = inp->inp_socket;
 	if (so != NULL) {
 		/*
 		 * If there's a socket, handle two cases: first, we own a
 		 * strong reference, which we will now release, or we don't
 		 * in which case another reference exists (XXXRW: think
 		 * about this more), and we don't need to take action.
 		 */
 		if (inp->inp_flags & INP_SOCKREF) {
 			inp->inp_flags &= ~INP_SOCKREF;
 			INP_WUNLOCK(inp);
 			ACCEPT_LOCK();
 			SOCK_LOCK(so);
 			KASSERT(so->so_state & SS_PROTOREF,
 			    ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
 			so->so_state &= ~SS_PROTOREF;
 			sofree(so);
 		} else {
 			/*
 			 * If we don't own the only reference, the socket and
 			 * inpcb need to be left around to be handled by
 			 * tcp_usr_detach() later.
 			 */
 			INP_WUNLOCK(inp);
 		}
 	} else
 		in_pcbfree(inp);
 	TCPSTAT_INC(tcps_closed);
 	//crfree(tw->tw_cred);
 	tw->tw_cred = NULL;
 	if (reuse)
 		return;
 	uma_zfree(V_tcptw_zone, tw);
 }

 int
 tcp_twrespond(struct tcptw *tw, int flags)
 {
 	struct inpcb *inp = tw->tw_inpcb;
 	struct tcphdr *th;
 	struct mbuf *m;
 	struct ip *ip = NULL;
 	u_int hdrlen, optlen;
 	int error;
 	struct tcpopt to;
 #ifdef INET6
 	struct ip6_hdr *ip6 = NULL;
 	int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
 #endif

 	INP_WLOCK_ASSERT(inp);

 	m = m_gethdr(M_DONTWAIT, MT_DATA);
 	if (m == NULL)
 		return (ENOBUFS);
 	m->m_data += max_linkhdr;

 #ifdef MAC
 	mac_inpcb_create_mbuf(inp, m);
 #endif

 #ifdef INET6
 	if (isipv6) {
 		hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
 		ip6 = mtod(m, struct ip6_hdr *);
 		th = (struct tcphdr *)(ip6 + 1);
 		tcpip_fillheaders(inp, ip6, th);
 	} else
 #endif
 	{
 		hdrlen = sizeof(struct tcpiphdr);
 		ip = mtod(m, struct ip *);
 		th = (struct tcphdr *)(ip + 1);
 		tcpip_fillheaders(inp, ip, th);
 	}
 	to.to_flags = 0;

 	/*
 	 * Send a timestamp and echo-reply if both our side and our peer
 	 * have sent timestamps in our SYN's and this is not a RST.
 	 */
 	if (tw->t_recent && flags == TH_ACK) {
 		to.to_flags |= TOF_TS;
 		to.to_tsval = bsd_ticks + tw->ts_offset;
 		to.to_tsecr = tw->t_recent;
 	}
 	optlen = tcp_addoptions(&to, (u_char *)(th + 1));

 	m->m_len = hdrlen + optlen;
 	m->m_pkthdr.len = m->m_len;

 	KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));

 	th->th_seq = htonl(tw->snd_nxt);
 	th->th_ack = htonl(tw->rcv_nxt);
 	th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
 	th->th_flags = flags;
 	th->th_win = htons(tw->last_win);

 #ifdef INET6
 	if (isipv6) {
 		th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
 		    sizeof(struct tcphdr) + optlen);
 		ip6->ip6_hlim = in6_selecthlim(inp, NULL);
 		error = ip6_output(m, inp->in6p_outputopts, NULL,
 		    (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
 	} else
 #endif
 	{
 		th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
 		    htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
 		m->m_pkthdr.csum_flags = CSUM_TCP;
 		m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
 		ip->ip_len = m->m_pkthdr.len;
 		if (V_path_mtu_discovery)
 			ip->ip_off |= IP_DF;
 		error = ip_output(m, inp->inp_options, NULL,
 		    ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
 		    NULL, inp);
 	}
 	if (flags & TH_ACK)
 		TCPSTAT_INC(tcps_sndacks);
 	else
 		TCPSTAT_INC(tcps_sndctrl);
 	TCPSTAT_INC(tcps_sndtotal);
 	return (error);
 }

 static void
 tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
 {

 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 	INP_WLOCK_ASSERT(tw->tw_inpcb);
 	if (rearm)
 		TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
 	tw->tw_time = bsd_ticks + 2 * tcp_msl;
 	TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
 }

 static void
 tcp_tw_2msl_stop(struct tcptw *tw)
 {

 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 	TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
 }

 struct tcptw *
 tcp_tw_2msl_scan(int reuse)
 {
 	struct tcptw *tw;

 	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 	for (;;) {
 		tw = TAILQ_FIRST(&V_twq_2msl);
 		if (tw == NULL || (!reuse && (tw->tw_time - bsd_ticks) > 0))
 			break;
 		INP_WLOCK(tw->tw_inpcb);
 		tcp_twclose(tw, reuse);
 		if (reuse)
 			return (tw);
 	}
 	return (NULL);
 }
	/*-
	* 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.
	* 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
	*/

	#include <sys/bsd_cdefs.h>
	//__FBSDID("$FreeBSD$");

	#include "bsd_opt_inet.h"
	#include "bsd_opt_inet6.h"
	#include "bsd_opt_tcpdebug.h"

	#include <sys/bsd_param.h>
	#include <sys/bsd_systm.h>
	#include <sys/bsd_callout.h>
	#include <sys/bsd_kernel.h>
	//baoyg//#include <sys/bsd_sysctl.h>
	#include <sys/bsd_malloc.h>
	#include <sys/bsd_mbuf.h>
	//#include <sys/bsd_priv.h>
	////#include <sys/bsd_proc.h>
	#include <sys/bsd_socket.h>
	#include <sys/bsd_socketvar.h>
	#include <sys/bsd_protosw.h>
	#include <sys/bsd_random.h>

	#include <vm/bsd_uma.h>

	#include <net/bsd_route.h>
	#include <net/bsd_if.h>
	#include <net/bsd_vnet.h>

	#include <netinet/bsd_in.h>
	#include <netinet/bsd_in_systm.h>
	#include <netinet/bsd_ip.h>
	#ifdef INET6
	#include <netinet/bsd_ip6.h>
	#endif
	#include <netinet/bsd_in_pcb.h>
	#ifdef INET6
	#include <netinet6/bsd_in6_pcb.h>
	#endif
	#include <netinet/bsd_in_var.h>
	#include <netinet/bsd_ip_var.h>
	#ifdef INET6
	#include <netinet6/bsd_ip6_var.h>
	#include <netinet6/bsd_scope6_var.h>
	#include <netinet6/bsd_nd6.h>
	#endif
	#include <netinet/bsd_ip_icmp.h>
	#include <netinet/bsd_tcp.h>
	#include <netinet/bsd_tcp_fsm.h>
	#include <netinet/bsd_tcp_seq.h>
	#include <netinet/bsd_tcp_timer.h>
	#include <netinet/bsd_tcp_var.h>
	#ifdef INET6
	#include <netinet6/bsd_tcp6_var.h>
	#endif
	#include <netinet/bsd_tcpip.h>
	#ifdef TCPDEBUG
	#include <netinet/bsd_tcp_debug.h>
	#endif
	#include <netinet6/bsd_ip6protosw.h>

	#include <machine/bsd_in_cksum.h>

	#ifdef MAC
	#include <security/mac/bsd_mac_framework.h>
	#endif

	extern int bsd_ticks;
	static int maxtcptw;

	/*
	* The timed wait queue contains references to each of the TCP sessions
	* currently in the TIME_WAIT state. The queue pointers, including the
	* queue pointers in each tcptw structure, are protected using the global
	* tcbinfo lock, which must be held over queue iteration and modification.
	*/
	static VNET_DEFINE(uma_zone_t, tcptw_zone);
	static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl);
	VNET_DEFINE(int, nolocaltimewait);

	#define V_tcptw_zone VNET(tcptw_zone)
	#define V_twq_2msl VNET(twq_2msl)

	static void tcp_tw_2msl_reset(struct tcptw *, int);
	static void tcp_tw_2msl_stop(struct tcptw *);

	static int
	tcptw_auto_size(void)
	{
	int halfrange;

	/*
	* Max out at half the ephemeral port range so that TIME_WAIT
	* sockets don't tie up too many ephemeral ports.
	*/
	if (V_ipport_lastauto > V_ipport_firstauto)
	halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2;
	else
	halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2;
	/* Protect against goofy port ranges smaller than 32. */
	return (imin(imax(halfrange, 32), maxsockets / 5));
	}
	/*
	static int
	sysctl_maxtcptw(SYSCTL_HANDLER_ARGS)
	{
	int error, new;

	if (maxtcptw == 0)
	new = tcptw_auto_size();
	else
	new = maxtcptw;
	error = sysctl_handle_int(oidp, &new, 0, req);
	if (error == 0 && req->newptr)
	if (new >= 32) {
	maxtcptw = new;
	uma_zone_set_max(V_tcptw_zone, maxtcptw);
	}
	return (error);
	}

	SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT\|CTLFLAG_RW,
	&maxtcptw, 0, sysctl_maxtcptw, "IU",
	"Maximum number of compressed TCP TIME_WAIT entries");

	SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_RW,
	&VNET_NAME(nolocaltimewait), 0,
	"Do not create compressed TCP TIME_WAIT entries for local connections");
	*/
	void
	tcp_tw_zone_change(void)
	{

	if (maxtcptw == 0)
	uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
	}

	void
	tcp_tw_init(void)
	{

	V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw),
	NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
	//TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw);
	if (maxtcptw == 0)
	uma_zone_set_max(V_tcptw_zone, tcptw_auto_size());
	else
	uma_zone_set_max(V_tcptw_zone, maxtcptw);
	TAILQ_INIT(&V_twq_2msl);
	}

	#ifdef VIMAGE
	void
	tcp_tw_destroy(void)
	{
	struct tcptw *tw;

	INP_INFO_WLOCK(&V_tcbinfo);
	while((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
	tcp_twclose(tw, 0);
	INP_INFO_WUNLOCK(&V_tcbinfo);
	}
	#endif

	/*
	* Move a TCP connection into TIME_WAIT state.
	* tcbinfo is locked.
	* inp is locked, and is unlocked before returning.
	*/
	void
	tcp_twstart(struct tcpcb *tp)
	{
	struct tcptw *tw;
	struct inpcb *inp = tp->t_inpcb;
	int acknow;
	struct socket *so;

	INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_reset(). */
	INP_WLOCK_ASSERT(inp);

	if (V_nolocaltimewait && in_localip(inp->inp_faddr)) {
	tp = tcp_close(tp);
	if (tp != NULL)
	INP_WUNLOCK(inp);
	return;
	}

	tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
	if (tw == NULL) {
	tw = tcp_tw_2msl_scan(1);
	if (tw == NULL) {
	tp = tcp_close(tp);
	if (tp != NULL)
	INP_WUNLOCK(inp);
	return;
	}
	}
	tw->tw_inpcb = inp;

	/*
	* Recover last window size sent.
	*/
	tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale;

	/*
	* Set t_recent if timestamps are used on the connection.
	*/
	if ((tp->t_flags & (TF_REQ_TSTMP\|TF_RCVD_TSTMP\|TF_NOOPT)) ==
	(TF_REQ_TSTMP\|TF_RCVD_TSTMP)) {
	tw->t_recent = tp->ts_recent;
	tw->ts_offset = tp->ts_offset;
	} else {
	tw->t_recent = 0;
	tw->ts_offset = 0;
	}

	tw->snd_nxt = tp->snd_nxt;
	tw->rcv_nxt = tp->rcv_nxt;
	tw->iss = tp->iss;
	tw->irs = tp->irs;
	tw->t_starttime = tp->t_starttime;
	tw->tw_time = 0;

	/* XXX
	* If this code will
	* be used for fin-wait-2 state also, then we may need
	* a ts_recent from the last segment.
	*/
	acknow = tp->t_flags & TF_ACKNOW;

	/*
	* First, discard tcpcb state, which includes stopping its timers and
	* freeing it. tcp_discardcb() used to also release the inpcb, but
	* that work is now done in the caller.
	*
	* Note: soisdisconnected() call used to be made in tcp_discardcb(),
	* and might not be needed here any longer.
	*/
	tcp_discardcb(tp);
	so = inp->inp_socket;
	soisdisconnected(so);
	tw->tw_cred = NULL;//crhold(so->so_cred);
	SOCK_LOCK(so);
	tw->tw_so_options = so->so_options;
	SOCK_UNLOCK(so);
	if (acknow)
	tcp_twrespond(tw, TH_ACK);
	inp->inp_ppcb = tw;
	inp->inp_flags \|= INP_TIMEWAIT;
	tcp_tw_2msl_reset(tw, 0);

	/*
	* If the inpcb owns the sole reference to the socket, then we can
	* detach and free the socket as it is not needed in time wait.
	*/
	if (inp->inp_flags & INP_SOCKREF) {
	KASSERT(so->so_state & SS_PROTOREF,
	("tcp_twstart: !SS_PROTOREF"));
	inp->inp_flags &= ~INP_SOCKREF;
	INP_WUNLOCK(inp);
	ACCEPT_LOCK();
	SOCK_LOCK(so);
	so->so_state &= ~SS_PROTOREF;
	sofree(so);
	} else
	INP_WUNLOCK(inp);
	}

	#if 0
	/*
	* The appromixate rate of ISN increase of Microsoft TCP stacks;
	* the actual rate is slightly higher due to the addition of
	* random positive increments.
	*
	* Most other new OSes use semi-randomized ISN values, so we
	* do not need to worry about them.
	*/
	#define MS_ISN_BYTES_PER_SECOND 250000

	/*
	* Determine if the ISN we will generate has advanced beyond the last
	* sequence number used by the previous connection. If so, indicate
	* that it is safe to recycle this tw socket by returning 1.
	*/
	int
	tcp_twrecycleable(struct tcptw *tw)
	{
	tcp_seq new_iss = tw->iss;
	tcp_seq new_irs = tw->irs;

	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
	new_iss += (bsd_ticks - tw->t_starttime) * (ISN_BYTES_PER_SECOND / hz);
	new_irs += (bsd_ticks - tw->t_starttime) * (MS_ISN_BYTES_PER_SECOND / hz);

	if (SEQ_GT(new_iss, tw->snd_nxt) && SEQ_GT(new_irs, tw->rcv_nxt))
	return (1);
	else
	return (0);
	}
	#endif

	/*
	* Returns 1 if the TIME_WAIT state was killed and we should start over,
	* looking for a pcb in the listen state. Returns 0 otherwise.
	*/
	int
	tcp_twcheck(struct inpcb inp, struct tcpopt to, struct tcphdr *th,
	struct mbuf *m, int tlen)
	{
	struct tcptw *tw;
	int thflags;
	tcp_seq seq;

	/* tcbinfo lock required for tcp_twclose(), tcp_tw_2msl_reset(). */
	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
	INP_WLOCK_ASSERT(inp);

	/*
	* XXXRW: Time wait state for inpcb has been recycled, but inpcb is
	* still present. This is undesirable, but temporarily necessary
	* until we work out how to handle inpcb's who's timewait state has
	* been removed.
	*/
	tw = intotw(inp);
	if (tw == NULL)
	goto drop;

	thflags = th->th_flags;

	/*
	* NOTE: for FIN_WAIT_2 (to be added later),
	* must validate sequence number before accepting RST
	*/

	/*
	* If the segment contains RST:
	* Drop the segment - see Stevens, vol. 2, p. 964 and
	* RFC 1337.
	*/
	if (thflags & TH_RST)
	goto drop;

	#if 0
	/* PAWS not needed at the moment */
	/*
	* RFC 1323 PAWS: If we have a timestamp reply on this segment
	* and it's less than ts_recent, drop it.
	*/
	if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent &&
	TSTMP_LT(to.to_tsval, tp->ts_recent)) {
	if ((thflags & TH_ACK) == 0)
	goto drop;
	goto ack;
	}
	/*
	* ts_recent is never updated because we never accept new segments.
	*/
	#endif

	/*
	* If a new connection request is received
	* while in TIME_WAIT, drop the old connection
	* and start over if the sequence numbers
	* are above the previous ones.
	*/
	if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) {
	tcp_twclose(tw, 0);
	return (1);
	}

	/*
	* Drop the the segment if it does not contain an ACK.
	*/
	if ((thflags & TH_ACK) == 0)
	goto drop;

	/*
	* Reset the 2MSL timer if this is a duplicate FIN.
	*/
	if (thflags & TH_FIN) {
	seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
	if (seq + 1 == tw->rcv_nxt)
	tcp_tw_2msl_reset(tw, 1);
	}

	/*
	* Acknowledge the segment if it has data or is not a duplicate ACK.
	*/
	if (thflags != TH_ACK \|\| tlen != 0 \|\|
	th->th_seq != tw->rcv_nxt \|\| th->th_ack != tw->snd_nxt)
	tcp_twrespond(tw, TH_ACK);
	drop:
	INP_WUNLOCK(inp);
	m_freem(m);
	return (0);
	}

	void
	tcp_twclose(struct tcptw *tw, int reuse)
	{
	struct socket *so;
	struct inpcb *inp;

	/*
	* At this point, we are in one of two situations:
	*
	* (1) We have no socket, just an inpcb<->twtcp pair. We can free
	* all state.
	*
	* (2) We have a socket -- if we own a reference, release it and
	* notify the socket layer.
	*/
	inp = tw->tw_inpcb;
	KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait"));
	KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw"));
	INP_INFO_WLOCK_ASSERT(&V_tcbinfo); /* tcp_tw_2msl_stop(). */
	INP_WLOCK_ASSERT(inp);

	tw->tw_inpcb = NULL;
	tcp_tw_2msl_stop(tw);
	inp->inp_ppcb = NULL;
	in_pcbdrop(inp);

	so = inp->inp_socket;
	if (so != NULL) {
	/*
	* If there's a socket, handle two cases: first, we own a
	* strong reference, which we will now release, or we don't
	* in which case another reference exists (XXXRW: think
	* about this more), and we don't need to take action.
	*/
	if (inp->inp_flags & INP_SOCKREF) {
	inp->inp_flags &= ~INP_SOCKREF;
	INP_WUNLOCK(inp);
	ACCEPT_LOCK();
	SOCK_LOCK(so);
	KASSERT(so->so_state & SS_PROTOREF,
	("tcp_twclose: INP_SOCKREF && !SS_PROTOREF"));
	so->so_state &= ~SS_PROTOREF;
	sofree(so);
	} else {
	/*
	* If we don't own the only reference, the socket and
	* inpcb need to be left around to be handled by
	* tcp_usr_detach() later.
	*/
	INP_WUNLOCK(inp);
	}
	} else
	in_pcbfree(inp);
	TCPSTAT_INC(tcps_closed);
	//crfree(tw->tw_cred);
	tw->tw_cred = NULL;
	if (reuse)
	return;
	uma_zfree(V_tcptw_zone, tw);
	}

	int
	tcp_twrespond(struct tcptw *tw, int flags)
	{
	struct inpcb *inp = tw->tw_inpcb;
	struct tcphdr *th;
	struct mbuf *m;
	struct ip *ip = NULL;
	u_int hdrlen, optlen;
	int error;
	struct tcpopt to;
	#ifdef INET6
	struct ip6_hdr *ip6 = NULL;
	int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
	#endif

	INP_WLOCK_ASSERT(inp);

	m = m_gethdr(M_DONTWAIT, MT_DATA);
	if (m == NULL)
	return (ENOBUFS);
	m->m_data += max_linkhdr;

	#ifdef MAC
	mac_inpcb_create_mbuf(inp, m);
	#endif

	#ifdef INET6
	if (isipv6) {
	hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
	ip6 = mtod(m, struct ip6_hdr *);
	th = (struct tcphdr *)(ip6 + 1);
	tcpip_fillheaders(inp, ip6, th);
	} else
	#endif
	{
	hdrlen = sizeof(struct tcpiphdr);
	ip = mtod(m, struct ip *);
	th = (struct tcphdr *)(ip + 1);
	tcpip_fillheaders(inp, ip, th);
	}
	to.to_flags = 0;

	/*
	* Send a timestamp and echo-reply if both our side and our peer
	* have sent timestamps in our SYN's and this is not a RST.
	*/
	if (tw->t_recent && flags == TH_ACK) {
	to.to_flags \|= TOF_TS;
	to.to_tsval = bsd_ticks + tw->ts_offset;
	to.to_tsecr = tw->t_recent;
	}
	optlen = tcp_addoptions(&to, (u_char *)(th + 1));

	m->m_len = hdrlen + optlen;
	m->m_pkthdr.len = m->m_len;

	KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small"));

	th->th_seq = htonl(tw->snd_nxt);
	th->th_ack = htonl(tw->rcv_nxt);
	th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
	th->th_flags = flags;
	th->th_win = htons(tw->last_win);

	#ifdef INET6
	if (isipv6) {
	th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
	sizeof(struct tcphdr) + optlen);
	ip6->ip6_hlim = in6_selecthlim(inp, NULL);
	error = ip6_output(m, inp->in6p_outputopts, NULL,
	(tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
	} else
	#endif
	{
	th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
	htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
	m->m_pkthdr.csum_flags = CSUM_TCP;
	m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
	ip->ip_len = m->m_pkthdr.len;
	if (V_path_mtu_discovery)
	ip->ip_off \|= IP_DF;
	error = ip_output(m, inp->inp_options, NULL,
	((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
	NULL, inp);
	}
	if (flags & TH_ACK)
	TCPSTAT_INC(tcps_sndacks);
	else
	TCPSTAT_INC(tcps_sndctrl);
	TCPSTAT_INC(tcps_sndtotal);
	return (error);
	}

	static void
	tcp_tw_2msl_reset(struct tcptw *tw, int rearm)
	{

	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
	INP_WLOCK_ASSERT(tw->tw_inpcb);
	if (rearm)
	TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
	tw->tw_time = bsd_ticks + 2 * tcp_msl;
	TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
	}

	static void
	tcp_tw_2msl_stop(struct tcptw *tw)
	{

	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
	TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
	}

	struct tcptw *
	tcp_tw_2msl_scan(int reuse)
	{
	struct tcptw *tw;

	INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
	for (;;) {
	tw = TAILQ_FIRST(&V_twq_2msl);
	if (tw == NULL \|\| (!reuse && (tw->tw_time - bsd_ticks) > 0))
	break;
	INP_WLOCK(tw->tw_inpcb);
	tcp_twclose(tw, reuse);
	if (reuse)
	return (tw);
	}
	return (NULL);
	}