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sys/netinet/tcp_timewait.c

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#include <netinet/udp_var.h> #include <netinet/udp_var.h>
#include <netipsec/ipsec_support.h> #include <netipsec/ipsec_support.h>
#include <machine/in_cksum.h> #include <machine/in_cksum.h>
#include <security/mac/mac_framework.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(bool, nolocaltimewait) = true; VNET_DEFINE_STATIC(bool, nolocaltimewait) = true;
#define V_nolocaltimewait VNET(nolocaltimewait) #define V_nolocaltimewait VNET(nolocaltimewait)
SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, nolocaltimewait,
&VNET_NAME(nolocaltimewait), true, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nolocaltimewait), true,
"Do not create compressed TCP TIME_WAIT entries for local connections"); "Do not create TCP TIME_WAIT state 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. * Move a TCP connection into TIME_WAIT state.
* tcbinfo is locked.
* inp is locked, and is unlocked before returning. * inp is locked, and is unlocked before returning.
*
* This function used to free tcpcb and allocate a compressed TCP time-wait
* structure tcptw. This served well for 20 years but is no longer relevant
* on modern machines in the modern internet. However, the function remains
* so that TCP stacks require less modification and we don't burn the bridge
* to go back to using compressed time-wait.
*/ */
void void
tcp_twstart(struct tcpcb *tp) tcp_twstart(struct tcpcb *tp)
{ {
struct tcptw twlocal, *tw;
struct inpcb *inp = tp->t_inpcb; struct inpcb *inp = tp->t_inpcb;
struct socket *so;
uint32_t recwin;
bool acknow, local;
#ifdef INET6 #ifdef INET6
bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; bool isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6;
#endif #endif
NET_EPOCH_ASSERT(); NET_EPOCH_ASSERT();
INP_WLOCK_ASSERT(inp); INP_WLOCK_ASSERT(inp);
/* A dropped inp should never transition to TIME_WAIT state. */ /* A dropped inp should never transition to TIME_WAIT state. */
KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: "
"(inp->inp_flags & INP_DROPPED) != 0")); "(inp->inp_flags & INP_DROPPED) != 0"));
if (V_nolocaltimewait) { tcp_state_change(tp, TCPS_TIME_WAIT);
soisdisconnected(inp->inp_socket);
if (tp->t_flags & TF_ACKNOW)
tcp_output(tp);
if (V_nolocaltimewait && (
#ifdef INET6 #ifdef INET6
if (isipv6) isipv6 ? in6_localaddr(&inp->in6p_faddr) :
local = in6_localaddr(&inp->in6p_faddr);
else
#endif #endif
#ifdef INET #ifdef INET
local = in_localip(inp->inp_faddr); in_localip(inp->inp_faddr)
#else #else
local = false; false
#endif #endif
} else )) {
local = false; if ((tp = tcp_close(tp)) != NULL)
INP_WUNLOCK(inp);
/* return;
* 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.
* If that fails, use on stack tw at least to be able to
* run through tcp_twrespond() and standard tcpcb discard
* routine.
*
* 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) {
tw = &twlocal;
local = true;
} }
}
/*
* For !local case the tcptw will hold a reference on its inpcb
* until tcp_twclose is called.
*/
tw->tw_inpcb = inp;
/* tcp_timer_activate(tp, TT_2MSL, 2 * V_tcp_msl);
* 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->t_port = tp->t_port;
tw->rcv_nxt = tp->rcv_nxt;
tw->tw_time = 0;
tw->tw_flags = tp->t_flags;
/* 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.
*/
#ifdef TCPHPTS
tcp_hpts_remove(inp);
#endif
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) {
inp->inp_flags &= ~INP_SOCKREF;
INP_WUNLOCK(inp); INP_WUNLOCK(inp);
sorele(so);
} else
INP_WUNLOCK(inp);
} }
/* /*
* Returns 1 if the TIME_WAIT state was killed and we should start over, * Returns true if the TIME_WAIT state was killed and we should start over,
* looking for a pcb in the listen state. Returns 0 otherwise. * looking for a pcb in the listen state. Otherwise returns false and frees
* the mbuf.
* *
* For pure SYN-segments the PCB shall be read-locked and the tcpopt pointer * For pure SYN-segments the PCB shall be read-locked and the tcpopt pointer
* may be NULL. For the rest write-lock and valid tcpopt. * may be NULL. For the rest write-lock and valid tcpopt.
*/ */
int bool
tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th, tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
struct mbuf *m, int tlen) struct mbuf *m, int tlen)
{ {
struct tcptw *tw; struct tcpcb *tp = intotcpcb(inp);
char *s; char *s;
int thflags; int thflags;
tcp_seq seq; tcp_seq seq;
NET_EPOCH_ASSERT(); NET_EPOCH_ASSERT();
INP_LOCK_ASSERT(inp); INP_LOCK_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 = tcp_get_flags(th); thflags = tcp_get_flags(th);
#ifdef INVARIANTS #ifdef INVARIANTS
if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN)
INP_RLOCK_ASSERT(inp); INP_RLOCK_ASSERT(inp);
else { else {
INP_WLOCK_ASSERT(inp); INP_WLOCK_ASSERT(inp);
KASSERT(to != NULL, KASSERT(to != NULL,
("%s: called without options on a non-SYN segment", ("%s: called without options on a non-SYN segment",
▲ Show 20 Lines • Show All 45 Lines • ▼ Show 20 Lines#endif
/* /*
* If a new connection request is received * If a new connection request is received
* while in TIME_WAIT, drop the old connection * while in TIME_WAIT, drop the old connection
* and start over if the sequence numbers * and start over if the sequence numbers
* are above the previous ones. * are above the previous ones.
* Allow UDP port number changes in this case. * Allow UDP port number changes in this case.
*/ */
if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) && if (((thflags & (TH_SYN | TH_ACK)) == TH_SYN) &&
SEQ_GT(th->th_seq, tw->rcv_nxt)) { SEQ_GT(th->th_seq, tp->rcv_nxt)) {
/* /*
* In case we can't upgrade our lock just pretend we have * In case we can't upgrade our lock just pretend we have
* lost this packet. * lost this packet.
*/ */
if (INP_TRY_UPGRADE(inp) == 0) if (INP_TRY_UPGRADE(inp) == 0)
goto drop; goto drop;
tcp_twclose(tw, 0); if ((tp = tcp_close(tp)) != NULL)
INP_WUNLOCK(inp);
TCPSTAT_INC(tcps_tw_recycles); TCPSTAT_INC(tcps_tw_recycles);
return (1); return (true);
} }
/* /*
* Send RST if UDP port numbers don't match * Send RST if UDP port numbers don't match
*/ */
if (tw->t_port != m->m_pkthdr.tcp_tun_port) { if (tp->t_port != m->m_pkthdr.tcp_tun_port) {
if (tcp_get_flags(th) & TH_ACK) { if (tcp_get_flags(th) & TH_ACK) {
tcp_respond(NULL, mtod(m, void *), th, m, tcp_respond(tp, mtod(m, void *), th, m,
(tcp_seq)0, th->th_ack, TH_RST); (tcp_seq)0, th->th_ack, TH_RST);
} else { } else {
if (tcp_get_flags(th) & TH_SYN) if (tcp_get_flags(th) & TH_SYN)
tlen++; tlen++;
if (tcp_get_flags(th) & TH_FIN) if (tcp_get_flags(th) & TH_FIN)
tlen++; tlen++;
tcp_respond(NULL, mtod(m, void *), th, m, tcp_respond(tp, mtod(m, void *), th, m,
th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK); th->th_seq+tlen, (tcp_seq)0, TH_RST|TH_ACK);
} }
INP_UNLOCK(inp); INP_UNLOCK(inp);
TCPSTAT_INC(tcps_tw_resets); TCPSTAT_INC(tcps_tw_resets);
return (0); return (false);
} }
/* /*
* Drop the segment if it does not contain an ACK. * Drop the segment if it does not contain an ACK.
*/ */
if ((thflags & TH_ACK) == 0) if ((thflags & TH_ACK) == 0)
goto drop; goto drop;
INP_WLOCK_ASSERT(inp); INP_WLOCK_ASSERT(inp);
/* /*
* If timestamps were negotiated during SYN/ACK and a * If timestamps were negotiated during SYN/ACK and a
* segment without a timestamp is received, silently drop * segment without a timestamp is received, silently drop
* the segment, unless the missing timestamps are tolerated. * the segment, unless the missing timestamps are tolerated.
* See section 3.2 of RFC 7323. * See section 3.2 of RFC 7323.
*/ */
if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0) && if (((to->to_flags & TOF_TS) == 0) && (tp->ts_recent != 0) &&
(V_tcp_tolerate_missing_ts == 0)) { (V_tcp_tolerate_missing_ts == 0)) {
goto drop; goto drop;
} }
/* /*
* Reset the 2MSL timer if this is a duplicate FIN. * Reset the 2MSL timer if this is a duplicate FIN.
*/ */
if (thflags & TH_FIN) { if (thflags & TH_FIN) {
seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0);
if (seq + 1 == tw->rcv_nxt) if (seq + 1 == tp->rcv_nxt)
tcp_tw_2msl_reset(tw, 1); tcp_timer_activate(tp, TT_2MSL, 2 * V_tcp_msl);
} }
/* /*
* Acknowledge the segment if it has data or is not a duplicate ACK. * Acknowledge the segment if it has data or is not a duplicate ACK.
*/ */
if (thflags != TH_ACK || tlen != 0 || if (thflags != TH_ACK || tlen != 0 ||
th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) { th->th_seq != tp->rcv_nxt || th->th_ack != tp->snd_nxt) {
TCP_PROBE5(receive, NULL, NULL, m, NULL, th); TCP_PROBE5(receive, NULL, NULL, m, NULL, th);
tcp_twrespond(tw, TH_ACK); tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt,
tp->snd_nxt, TH_ACK);
INP_UNLOCK(inp);
TCPSTAT_INC(tcps_tw_responds); TCPSTAT_INC(tcps_tw_responds);
goto dropnoprobe; return (false);
} }
drop: drop:
TCP_PROBE5(receive, NULL, NULL, m, NULL, th); TCP_PROBE5(receive, NULL, NULL, m, NULL, th);
dropnoprobe:
INP_UNLOCK(inp); INP_UNLOCK(inp);
m_freem(m); m_freem(m);
return (0); return (false);
}
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);
sorele(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, ulen;
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
struct udphdr *udp = NULL;
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 *);
if (tw->t_port) {
udp = (struct udphdr *)(ip6 + 1);
hdrlen += sizeof(struct udphdr);
udp->uh_sport = htons(V_tcp_udp_tunneling_port);
udp->uh_dport = tw->t_port;
ulen = (hdrlen - sizeof(struct ip6_hdr));
th = (struct tcphdr *)(udp + 1);
} else
th = (struct tcphdr *)(ip6 + 1);
tcpip_fillheaders(inp, tw->t_port, ip6, th);
}
#endif
#if defined(INET6) && defined(INET)
else
#endif
#ifdef INET
{
hdrlen = sizeof(struct tcpiphdr);
ip = mtod(m, struct ip *);
if (tw->t_port) {
udp = (struct udphdr *)(ip + 1);
hdrlen += sizeof(struct udphdr);
udp->uh_sport = htons(V_tcp_udp_tunneling_port);
udp->uh_dport = tw->t_port;
ulen = (hdrlen - sizeof(struct ip));
th = (struct tcphdr *)(udp + 1);
} else
th = (struct tcphdr *)(ip + 1);
tcpip_fillheaders(inp, tw->t_port, 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;
}
#if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
if (tw->tw_flags & TF_SIGNATURE)
to.to_flags |= TOF_SIGNATURE;
#endif
optlen = tcp_addoptions(&to, (u_char *)(th + 1));
if (udp) {
ulen += optlen;
udp->uh_ulen = htons(ulen);
}
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;
tcp_set_flags(th, flags);
th->th_win = htons(tw->last_win);
#if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE)
if (tw->tw_flags & TF_SIGNATURE) {
if (!TCPMD5_ENABLED() ||
TCPMD5_OUTPUT(m, th, to.to_signature) != 0)
return (-1);
}
#endif
#ifdef INET6
if (isipv6) {
if (tw->t_port) {
m->m_pkthdr.csum_flags = CSUM_UDP_IPV6;
m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0);
th->th_sum = htons(0);
} else {
m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
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
{
if (tw->t_port) {
m->m_pkthdr.csum_flags = CSUM_UDP;
m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum);
udp->uh_sum = in_pseudo(ip->ip_src.s_addr,
ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP));
th->th_sum = htons(0);
} else {
m->m_pkthdr.csum_flags = CSUM_TCP;
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
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 * V_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;
} }