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- /*-
- * SPDX-License-Identifier: BSD-3-Clause
- *
- * 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. 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/cdefs.h>
- __FBSDID("$FreeBSD$");
- #include "opt_inet.h"
- #include "opt_inet6.h"
- #include "opt_tcpdebug.h"
- #include <sys/param.h>
- #include <sys/systm.h>
- #include <sys/callout.h>
- #include <sys/kernel.h>
- #include <sys/sysctl.h>
- #include <sys/malloc.h>
- #include <sys/mbuf.h>
- #include <sys/priv.h>
- #include <sys/proc.h>
- #include <sys/socket.h>
- #include <sys/socketvar.h>
- #ifndef INVARIANTS
- #include <sys/syslog.h>
- #endif
- #include <sys/protosw.h>
- #include <sys/random.h>
- #include <vm/uma.h>
- #include <net/route.h>
- #include <net/if.h>
- #include <net/if_var.h>
- #include <net/vnet.h>
- #include <netinet/in.h>
- #include <netinet/in_kdtrace.h>
- #include <netinet/in_pcb.h>
- #include <netinet/in_systm.h>
- #include <netinet/in_var.h>
- #include <netinet/ip.h>
- #include <netinet/ip_icmp.h>
- #include <netinet/ip_var.h>
- #ifdef INET6
- #include <netinet/ip6.h>
- #include <netinet6/in6_pcb.h>
- #include <netinet6/ip6_var.h>
- #include <netinet6/scope6_var.h>
- #include <netinet6/nd6.h>
- #endif
- #include <netinet/tcp.h>
- #include <netinet/tcp_fsm.h>
- #include <netinet/tcp_seq.h>
- #include <netinet/tcp_timer.h>
- #include <netinet/tcp_var.h>
- #ifdef INET6
- #include <netinet6/tcp6_var.h>
- #endif
- #include <netinet/tcpip.h>
- #ifdef TCPDEBUG
- #include <netinet/tcp_debug.h>
- #endif
- #ifdef INET6
- #include <netinet6/ip6protosw.h>
- #endif
- #include <machine/in_cksum.h>
- #include <security/mac/mac_framework.h>
- VNET_DEFINE_STATIC(uma_zone_t, tcptw_zone);
- #define V_tcptw_zone VNET(tcptw_zone)
- 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
- * timewait lock, which must be held over queue iteration and modification.
- *
- * Rules on tcptw usage:
- * - a inpcb is always freed _after_ its tcptw
- * - a tcptw relies on its inpcb reference counting for memory stability
- * - a tcptw is dereferenceable only while its inpcb is locked
- */
- VNET_DEFINE_STATIC(TAILQ_HEAD(, tcptw), twq_2msl);
- #define V_twq_2msl VNET(twq_2msl)
- /* Global timewait lock */
- VNET_DEFINE_STATIC(struct rwlock, tw_lock);
- #define V_tw_lock VNET(tw_lock)
- #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0)
- #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw))
- #define TW_RLOCK(tw) rw_rlock(&(tw))
- #define TW_WLOCK(tw) rw_wlock(&(tw))
- #define TW_RUNLOCK(tw) rw_runlock(&(tw))
- #define TW_WUNLOCK(tw) rw_wunlock(&(tw))
- #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED)
- #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED)
- #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED)
- #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED)
- static void tcp_tw_2msl_reset(struct tcptw *, int);
- static void tcp_tw_2msl_stop(struct tcptw *, int);
- static int tcp_twrespond(struct tcptw *, int);
- 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 | CTLFLAG_NEEDGIANT,
- &maxtcptw, 0, sysctl_maxtcptw, "IU",
- "Maximum number of compressed TCP TIME_WAIT entries");
- VNET_DEFINE_STATIC(int, nolocaltimewait) = 0;
- #define V_nolocaltimewait VNET(nolocaltimewait)
- SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | 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, 0);
- 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);
- TW_LOCK_INIT(V_tw_lock, "tcptw");
- }
- #ifdef VIMAGE
- void
- tcp_tw_destroy(void)
- {
- struct tcptw *tw;
- struct epoch_tracker et;
- NET_EPOCH_ENTER(et);
- while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL)
- tcp_twclose(tw, 0);
- NET_EPOCH_EXIT(et);
- TW_LOCK_DESTROY(V_tw_lock);
- uma_zdestroy(V_tcptw_zone);
- }
- #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 twlocal, *tw;
- struct inpcb *inp = tp->t_inpcb;
- struct socket *so;
- uint32_t recwin;
- bool acknow, local;
- #ifdef INET6
- bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
- #endif
- NET_EPOCH_ASSERT();
- INP_WLOCK_ASSERT(inp);
- /* A dropped inp should never transition to TIME_WAIT state. */
- KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: "
- "(inp->inp_flags & INP_DROPPED) != 0"));
- if (V_nolocaltimewait) {
- #ifdef INET6
- if (isipv6)
- local = in6_localaddr(&inp->in6p_faddr);
- else
- #endif
- #ifdef INET
- local = in_localip(inp->inp_faddr);
- #else
- local = false;
- #endif
- } else
- local = false;
- /*
- * For use only by DTrace. We do not reference the state
- * after this point so modifying it in place is not a problem.
- */
- tcp_state_change(tp, TCPS_TIME_WAIT);
- if (local)
- tw = &twlocal;
- else
- tw = uma_zalloc(V_tcptw_zone, M_NOWAIT);
- if (tw == NULL) {
- /*
- * Reached limit on total number of TIMEWAIT connections
- * allowed. Remove a connection from TIMEWAIT queue in LRU
- * fashion to make room for this connection.
- *
- * XXX: Check if it possible to always have enough room
- * in advance based on guarantees provided by uma_zalloc().
- */
- tw = tcp_tw_2msl_scan(1);
- if (tw == NULL) {
- tp = tcp_close(tp);
- if (tp != NULL)
- INP_WUNLOCK(inp);
- return;
- }
- }
- /*
- * For !local case the tcptw will hold a reference on its inpcb
- * until tcp_twclose is called.
- */
- tw->tw_inpcb = inp;
- /*
- * Recover last window size sent.
- */
- so = inp->inp_socket;
- recwin = lmin(lmax(sbspace(&so->so_rcv), 0),
- (long)TCP_MAXWIN << tp->rcv_scale);
- if (recwin < (so->so_rcv.sb_hiwat / 4) &&
- recwin < tp->t_maxseg)
- recwin = 0;
- if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) &&
- recwin < (tp->rcv_adv - tp->rcv_nxt))
- recwin = (tp->rcv_adv - tp->rcv_nxt);
- tw->last_win = (u_short)(recwin >> 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);
- soisdisconnected(so);
- tw->tw_so_options = so->so_options;
- inp->inp_flags |= INP_TIMEWAIT;
- if (acknow)
- tcp_twrespond(tw, TH_ACK);
- if (local)
- in_pcbdrop(inp);
- else {
- in_pcbref(inp); /* Reference from tw */
- tw->tw_cred = crhold(so->so_cred);
- inp->inp_ppcb = tw;
- TCPSTATES_INC(TCPS_TIME_WAIT);
- 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);
- SOCK_LOCK(so);
- so->so_state &= ~SS_PROTOREF;
- sofree(so);
- } else
- INP_WUNLOCK(inp);
- }
- /*
- * 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.
- * It be called with to == NULL only for pure SYN-segments.
- */
- 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;
- NET_EPOCH_ASSERT();
- 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;
- KASSERT(to != NULL || (thflags & (TH_SYN | TH_ACK)) == TH_SYN,
- ("tcp_twcheck: called without options on a non-SYN segment"));
- /*
- * 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 segment if it does not contain an ACK.
- */
- if ((thflags & TH_ACK) == 0)
- goto drop;
- /*
- * If timestamps were negotiated during SYN/ACK and a
- * segment without a timestamp is received, silently drop
- * the segment, unless the missing timestamps are tolerated.
- * See section 3.2 of RFC 7323.
- */
- if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) &&
- (V_tcp_tolerate_missing_ts == 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_PROBE5(receive, NULL, NULL, m, NULL, th);
- tcp_twrespond(tw, TH_ACK);
- goto dropnoprobe;
- }
- drop:
- TCP_PROBE5(receive, NULL, NULL, m, NULL, th);
- dropnoprobe:
- 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"));
- NET_EPOCH_ASSERT();
- INP_WLOCK_ASSERT(inp);
- tcp_tw_2msl_stop(tw, reuse);
- 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);
- 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 {
- /*
- * The socket has been already cleaned-up for us, only free the
- * inpcb.
- */
- in_pcbfree(inp);
- }
- TCPSTAT_INC(tcps_closed);
- }
- static int
- tcp_twrespond(struct tcptw *tw, int flags)
- {
- struct inpcb *inp = tw->tw_inpcb;
- #if defined(INET6) || defined(INET)
- struct tcphdr *th = NULL;
- #endif
- struct mbuf *m;
- #ifdef INET
- struct ip *ip = NULL;
- #endif
- u_int hdrlen, optlen;
- int error = 0; /* Keep compiler happy */
- struct tcpopt to;
- #ifdef INET6
- struct ip6_hdr *ip6 = NULL;
- int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
- #endif
- hdrlen = 0; /* Keep compiler happy */
- INP_WLOCK_ASSERT(inp);
- m = m_gethdr(M_NOWAIT, 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);
- }
- #endif
- #if defined(INET6) && defined(INET)
- else
- #endif
- #ifdef INET
- {
- hdrlen = sizeof(struct tcpiphdr);
- ip = mtod(m, struct ip *);
- th = (struct tcphdr *)(ip + 1);
- tcpip_fillheaders(inp, ip, th);
- }
- #endif
- 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 = tcp_ts_getticks() + 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);
- m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
- #ifdef INET6
- if (isipv6) {
- m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
- th->th_sum = in6_cksum_pseudo(ip6,
- sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0);
- ip6->ip6_hlim = in6_selecthlim(inp, NULL);
- TCP_PROBE5(send, NULL, NULL, ip6, NULL, th);
- error = ip6_output(m, inp->in6p_outputopts, NULL,
- (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp);
- }
- #endif
- #if defined(INET6) && defined(INET)
- else
- #endif
- #ifdef INET
- {
- m->m_pkthdr.csum_flags = CSUM_TCP;
- th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
- htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP));
- ip->ip_len = htons(m->m_pkthdr.len);
- if (V_path_mtu_discovery)
- ip->ip_off |= htons(IP_DF);
- TCP_PROBE5(send, NULL, NULL, ip, NULL, th);
- error = ip_output(m, inp->inp_options, NULL,
- ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0),
- NULL, inp);
- }
- #endif
- 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)
- {
- NET_EPOCH_ASSERT();
- INP_WLOCK_ASSERT(tw->tw_inpcb);
- TW_WLOCK(V_tw_lock);
- if (rearm)
- TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
- tw->tw_time = ticks + 2 * tcp_msl;
- TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl);
- TW_WUNLOCK(V_tw_lock);
- }
- static void
- tcp_tw_2msl_stop(struct tcptw *tw, int reuse)
- {
- struct ucred *cred;
- struct inpcb *inp;
- int released __unused;
- NET_EPOCH_ASSERT();
- TW_WLOCK(V_tw_lock);
- inp = tw->tw_inpcb;
- tw->tw_inpcb = NULL;
- TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl);
- cred = tw->tw_cred;
- tw->tw_cred = NULL;
- TW_WUNLOCK(V_tw_lock);
- if (cred != NULL)
- crfree(cred);
- released = in_pcbrele_wlocked(inp);
- KASSERT(!released, ("%s: inp should not be released here", __func__));
- if (!reuse)
- uma_zfree(V_tcptw_zone, tw);
- TCPSTATES_DEC(TCPS_TIME_WAIT);
- }
- struct tcptw *
- tcp_tw_2msl_scan(int reuse)
- {
- struct tcptw *tw;
- struct inpcb *inp;
- NET_EPOCH_ASSERT();
- for (;;) {
- TW_RLOCK(V_tw_lock);
- tw = TAILQ_FIRST(&V_twq_2msl);
- if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) {
- TW_RUNLOCK(V_tw_lock);
- break;
- }
- KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL",
- __func__));
- inp = tw->tw_inpcb;
- in_pcbref(inp);
- TW_RUNLOCK(V_tw_lock);
- INP_WLOCK(inp);
- tw = intotw(inp);
- if (in_pcbrele_wlocked(inp)) {
- if (__predict_true(tw == NULL)) {
- continue;
- } else {
- /* This should not happen as in TIMEWAIT
- * state the inp should not be destroyed
- * before its tcptw. If INVARIANTS is
- * defined panic.
- */
- #ifdef INVARIANTS
- panic("%s: Panic before an infinite "
- "loop: INP_TIMEWAIT && (INP_FREED "
- "|| inp last reference) && tw != "
- "NULL", __func__);
- #else
- log(LOG_ERR, "%s: Avoid an infinite "
- "loop: INP_TIMEWAIT && (INP_FREED "
- "|| inp last reference) && tw != "
- "NULL", __func__);
- #endif
- break;
- }
- }
- if (tw == NULL) {
- /* tcp_twclose() has already been called */
- INP_WUNLOCK(inp);
- continue;
- }
- tcp_twclose(tw, reuse);
- if (reuse)
- return tw;
- }
- return NULL;
- }
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