/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, Joyent Inc. All rights reserved. */ /* * This file contains functions related to TCP time wait processing. Also * refer to the time wait handling comments in tcp_impl.h. */ #include #include #include #include #include #include #include #include #include #include static void tcp_timewait_close(void *, mblk_t *, void *, ip_recv_attr_t *); /* * TCP_TIME_WAIT_DELAY governs how often the time_wait_collector runs. * Running it every 5 seconds seems to give the best results. */ #define TCP_TIME_WAIT_DELAY ((hrtime_t)5 * NANOSEC) /* * Remove a connection from the list of detached TIME_WAIT connections. * It returns B_FALSE if it can't remove the connection from the list * as the connection has already been removed from the list due to an * earlier call to tcp_time_wait_remove(); otherwise it returns B_TRUE. */ boolean_t tcp_time_wait_remove(tcp_t *tcp, tcp_squeue_priv_t *tcp_time_wait) { boolean_t locked = B_FALSE; if (tcp_time_wait == NULL) { tcp_time_wait = *((tcp_squeue_priv_t **) squeue_getprivate(tcp->tcp_connp->conn_sqp, SQPRIVATE_TCP)); mutex_enter(&tcp_time_wait->tcp_time_wait_lock); locked = B_TRUE; } else { ASSERT(MUTEX_HELD(&tcp_time_wait->tcp_time_wait_lock)); } /* 0 means that the tcp_t has not been added to the time wait list. */ if (tcp->tcp_time_wait_expire == 0) { ASSERT(tcp->tcp_time_wait_next == NULL); ASSERT(tcp->tcp_time_wait_prev == NULL); if (locked) mutex_exit(&tcp_time_wait->tcp_time_wait_lock); return (B_FALSE); } ASSERT(TCP_IS_DETACHED(tcp)); ASSERT(tcp->tcp_state == TCPS_TIME_WAIT); if (tcp == tcp_time_wait->tcp_time_wait_head) { ASSERT(tcp->tcp_time_wait_prev == NULL); tcp_time_wait->tcp_time_wait_head = tcp->tcp_time_wait_next; if (tcp_time_wait->tcp_time_wait_head != NULL) { tcp_time_wait->tcp_time_wait_head->tcp_time_wait_prev = NULL; } else { tcp_time_wait->tcp_time_wait_tail = NULL; } } else if (tcp == tcp_time_wait->tcp_time_wait_tail) { ASSERT(tcp->tcp_time_wait_next == NULL); tcp_time_wait->tcp_time_wait_tail = tcp->tcp_time_wait_prev; ASSERT(tcp_time_wait->tcp_time_wait_tail != NULL); tcp_time_wait->tcp_time_wait_tail->tcp_time_wait_next = NULL; } else { ASSERT(tcp->tcp_time_wait_prev->tcp_time_wait_next == tcp); ASSERT(tcp->tcp_time_wait_next->tcp_time_wait_prev == tcp); tcp->tcp_time_wait_prev->tcp_time_wait_next = tcp->tcp_time_wait_next; tcp->tcp_time_wait_next->tcp_time_wait_prev = tcp->tcp_time_wait_prev; } tcp->tcp_time_wait_next = NULL; tcp->tcp_time_wait_prev = NULL; tcp->tcp_time_wait_expire = 0; if (locked) mutex_exit(&tcp_time_wait->tcp_time_wait_lock); return (B_TRUE); } /* Constants used for fast checking of a localhost address */ #if defined(_BIG_ENDIAN) #define IPv4_LOCALHOST 0x7f000000U #define IPv4_LH_MASK 0xffffff00U #else #define IPv4_LOCALHOST 0x0000007fU #define IPv4_LH_MASK 0x00ffffffU #endif #define IS_LOCAL_HOST(x) ( \ ((x)->tcp_connp->conn_ipversion == IPV4_VERSION && \ ((x)->tcp_connp->conn_laddr_v4 & IPv4_LH_MASK) == IPv4_LOCALHOST) || \ ((x)->tcp_connp->conn_ipversion == IPV6_VERSION && \ IN6_IS_ADDR_LOOPBACK(&(x)->tcp_connp->conn_laddr_v6))) /* * Add a connection to the list of detached TIME_WAIT connections * and set its time to expire. */ void tcp_time_wait_append(tcp_t *tcp) { tcp_stack_t *tcps = tcp->tcp_tcps; squeue_t *sqp = tcp->tcp_connp->conn_sqp; tcp_squeue_priv_t *tcp_time_wait = *((tcp_squeue_priv_t **)squeue_getprivate(sqp, SQPRIVATE_TCP)); hrtime_t firetime = 0; tcp_timers_stop(tcp); /* Freed above */ ASSERT(tcp->tcp_timer_tid == 0); ASSERT(tcp->tcp_ack_tid == 0); /* must have happened at the time of detaching the tcp */ ASSERT(tcp->tcp_ptpahn == NULL); ASSERT(tcp->tcp_flow_stopped == 0); ASSERT(tcp->tcp_time_wait_next == NULL); ASSERT(tcp->tcp_time_wait_prev == NULL); ASSERT(tcp->tcp_time_wait_expire == 0); ASSERT(tcp->tcp_listener == NULL); tcp->tcp_time_wait_expire = ddi_get_lbolt64(); if (IS_LOCAL_HOST(tcp)) { /* * This is the fastpath for handling localhost connections. * Since we don't have to worry about packets on the localhost * showing up after a long network delay, we want to expire * these quickly so the port range on the localhost doesn't * get starved by short-running, local apps. * * Leave tcp_time_wait_expire at the current time. This * essentially means the connection is expired now and it will * clean up the next time tcp_time_wait_collector runs. We set * firetime to use a short delay so that if we have to start a * tcp_time_wait_collector thread below, it runs soon instead * of after a delay of time_wait_interval. firetime being set * to a non-0 value is also our indicator that we should add * this connection to the head of the time wait list (since we * are already expired) so that its sure to get cleaned up on * the next run of tcp_time_wait_collector (which expects the * entries to appear in time-order and stops when it hits the * first non-expired entry). */ firetime = TCP_TIME_WAIT_DELAY; } else { /* * Since tcp_time_wait_expire is lbolt64, it should not wrap * around in practice. Hence it cannot be 0. Note that zero * means that the tcp_t is not in the TIME_WAIT list. */ tcp->tcp_time_wait_expire += MSEC_TO_TICK( tcps->tcps_time_wait_interval); } ASSERT(TCP_IS_DETACHED(tcp)); ASSERT(tcp->tcp_state == TCPS_TIME_WAIT); ASSERT(tcp->tcp_time_wait_next == NULL); ASSERT(tcp->tcp_time_wait_prev == NULL); TCP_DBGSTAT(tcps, tcp_time_wait); mutex_enter(&tcp_time_wait->tcp_time_wait_lock); if (tcp_time_wait->tcp_time_wait_head == NULL) { ASSERT(tcp_time_wait->tcp_time_wait_tail == NULL); tcp_time_wait->tcp_time_wait_head = tcp; /* * Even if the list was empty before, there may be a timer * running since a tcp_t can be removed from the list * in other places, such as tcp_clean_death(). So check if * a timer is needed. */ if (tcp_time_wait->tcp_time_wait_tid == 0) { if (firetime == 0) firetime = (hrtime_t) (tcps->tcps_time_wait_interval + 1) * MICROSEC; tcp_time_wait->tcp_time_wait_tid = timeout_generic(CALLOUT_NORMAL, tcp_time_wait_collector, sqp, firetime, CALLOUT_TCP_RESOLUTION, CALLOUT_FLAG_ROUNDUP); } tcp_time_wait->tcp_time_wait_tail = tcp; } else { /* * The list is not empty, so a timer must be running. If not, * tcp_time_wait_collector() must be running on this * tcp_time_wait list at the same time. */ ASSERT(tcp_time_wait->tcp_time_wait_tid != 0 || tcp_time_wait->tcp_time_wait_running); ASSERT(tcp_time_wait->tcp_time_wait_tail != NULL); ASSERT(tcp_time_wait->tcp_time_wait_tail->tcp_state == TCPS_TIME_WAIT); if (firetime == 0) { /* add at end */ tcp_time_wait->tcp_time_wait_tail->tcp_time_wait_next = tcp; tcp->tcp_time_wait_prev = tcp_time_wait->tcp_time_wait_tail; tcp_time_wait->tcp_time_wait_tail = tcp; } else { /* add at head */ tcp->tcp_time_wait_next = tcp_time_wait->tcp_time_wait_head; tcp_time_wait->tcp_time_wait_head->tcp_time_wait_prev = tcp; tcp_time_wait->tcp_time_wait_head = tcp; } } mutex_exit(&tcp_time_wait->tcp_time_wait_lock); } /* * Wrapper to call tcp_close_detached() via squeue to clean up TIME-WAIT * tcp_t. Used in tcp_time_wait_collector(). */ /* ARGSUSED */ static void tcp_timewait_close(void *arg, mblk_t *mp, void *arg2, ip_recv_attr_t *dummy) { conn_t *connp = (conn_t *)arg; tcp_t *tcp = connp->conn_tcp; ASSERT(tcp != NULL); if (tcp->tcp_state == TCPS_CLOSED) { return; } ASSERT((connp->conn_family == AF_INET && connp->conn_ipversion == IPV4_VERSION) || (connp->conn_family == AF_INET6 && (connp->conn_ipversion == IPV4_VERSION || connp->conn_ipversion == IPV6_VERSION))); ASSERT(!tcp->tcp_listener); ASSERT(TCP_IS_DETACHED(tcp)); /* * Because they have no upstream client to rebind or tcp_close() * them later, we axe the connection here and now. */ tcp_close_detached(tcp); } /* * Blows away all tcps whose TIME_WAIT has expired. List traversal * is done forwards from the head. * This walks all stack instances since * tcp_time_wait remains global across all stacks. */ /* ARGSUSED */ void tcp_time_wait_collector(void *arg) { tcp_t *tcp; int64_t now; mblk_t *mp; conn_t *connp; kmutex_t *lock; boolean_t removed; extern void (*cl_inet_disconnect)(netstackid_t, uint8_t, sa_family_t, uint8_t *, in_port_t, uint8_t *, in_port_t, void *); squeue_t *sqp = (squeue_t *)arg; tcp_squeue_priv_t *tcp_time_wait = *((tcp_squeue_priv_t **)squeue_getprivate(sqp, SQPRIVATE_TCP)); mutex_enter(&tcp_time_wait->tcp_time_wait_lock); tcp_time_wait->tcp_time_wait_tid = 0; #ifdef DEBUG tcp_time_wait->tcp_time_wait_running = B_TRUE; #endif if (tcp_time_wait->tcp_free_list != NULL && tcp_time_wait->tcp_free_list->tcp_in_free_list == B_TRUE) { TCP_G_STAT(tcp_freelist_cleanup); while ((tcp = tcp_time_wait->tcp_free_list) != NULL) { tcp_time_wait->tcp_free_list = tcp->tcp_time_wait_next; tcp->tcp_time_wait_next = NULL; tcp_time_wait->tcp_free_list_cnt--; ASSERT(tcp->tcp_tcps == NULL); CONN_DEC_REF(tcp->tcp_connp); } ASSERT(tcp_time_wait->tcp_free_list_cnt == 0); } /* * In order to reap time waits reliably, we should use a * source of time that is not adjustable by the user -- hence * the call to ddi_get_lbolt64(). */ now = ddi_get_lbolt64(); while ((tcp = tcp_time_wait->tcp_time_wait_head) != NULL) { /* * lbolt64 should not wrap around in practice... So we can * do a direct comparison. */ if (now < tcp->tcp_time_wait_expire) break; removed = tcp_time_wait_remove(tcp, tcp_time_wait); ASSERT(removed); connp = tcp->tcp_connp; ASSERT(connp->conn_fanout != NULL); lock = &connp->conn_fanout->connf_lock; /* * This is essentially a TW reclaim fast path optimization for * performance where the timewait collector checks under the * fanout lock (so that no one else can get access to the * conn_t) that the refcnt is 2 i.e. one for TCP and one for * the classifier hash list. If ref count is indeed 2, we can * just remove the conn under the fanout lock and avoid * cleaning up the conn under the squeue, provided that * clustering callbacks are not enabled. If clustering is * enabled, we need to make the clustering callback before * setting the CONDEMNED flag and after dropping all locks and * so we forego this optimization and fall back to the slow * path. Also please see the comments in tcp_closei_local * regarding the refcnt logic. * * Since we are holding the tcp_time_wait_lock, its better * not to block on the fanout_lock because other connections * can't add themselves to time_wait list. So we do a * tryenter instead of mutex_enter. */ if (mutex_tryenter(lock)) { mutex_enter(&connp->conn_lock); if ((connp->conn_ref == 2) && (cl_inet_disconnect == NULL)) { ipcl_hash_remove_locked(connp, connp->conn_fanout); /* * Set the CONDEMNED flag now itself so that * the refcnt cannot increase due to any * walker. */ connp->conn_state_flags |= CONN_CONDEMNED; mutex_exit(lock); mutex_exit(&connp->conn_lock); if (tcp_time_wait->tcp_free_list_cnt < tcp_free_list_max_cnt) { /* Add to head of tcp_free_list */ mutex_exit( &tcp_time_wait->tcp_time_wait_lock); tcp_cleanup(tcp); ASSERT(connp->conn_latch == NULL); ASSERT(connp->conn_policy == NULL); ASSERT(tcp->tcp_tcps == NULL); ASSERT(connp->conn_netstack == NULL); mutex_enter( &tcp_time_wait->tcp_time_wait_lock); tcp->tcp_time_wait_next = tcp_time_wait->tcp_free_list; tcp_time_wait->tcp_free_list = tcp; tcp_time_wait->tcp_free_list_cnt++; continue; } else { /* Do not add to tcp_free_list */ mutex_exit( &tcp_time_wait->tcp_time_wait_lock); tcp_bind_hash_remove(tcp); ixa_cleanup(tcp->tcp_connp->conn_ixa); tcp_ipsec_cleanup(tcp); CONN_DEC_REF(tcp->tcp_connp); } } else { CONN_INC_REF_LOCKED(connp); mutex_exit(lock); mutex_exit(&tcp_time_wait->tcp_time_wait_lock); mutex_exit(&connp->conn_lock); /* * We can reuse the closemp here since conn has * detached (otherwise we wouldn't even be in * time_wait list). tcp_closemp_used can safely * be changed without taking a lock as no other * thread can concurrently access it at this * point in the connection lifecycle. */ if (tcp->tcp_closemp.b_prev == NULL) tcp->tcp_closemp_used = B_TRUE; else cmn_err(CE_PANIC, "tcp_timewait_collector: " "concurrent use of tcp_closemp: " "connp %p tcp %p\n", (void *)connp, (void *)tcp); TCP_DEBUG_GETPCSTACK(tcp->tcmp_stk, 15); mp = &tcp->tcp_closemp; SQUEUE_ENTER_ONE(connp->conn_sqp, mp, tcp_timewait_close, connp, NULL, SQ_FILL, SQTAG_TCP_TIMEWAIT); } } else { mutex_enter(&connp->conn_lock); CONN_INC_REF_LOCKED(connp); mutex_exit(&tcp_time_wait->tcp_time_wait_lock); mutex_exit(&connp->conn_lock); /* * We can reuse the closemp here since conn has * detached (otherwise we wouldn't even be in * time_wait list). tcp_closemp_used can safely * be changed without taking a lock as no other * thread can concurrently access it at this * point in the connection lifecycle. */ if (tcp->tcp_closemp.b_prev == NULL) tcp->tcp_closemp_used = B_TRUE; else cmn_err(CE_PANIC, "tcp_timewait_collector: " "concurrent use of tcp_closemp: " "connp %p tcp %p\n", (void *)connp, (void *)tcp); TCP_DEBUG_GETPCSTACK(tcp->tcmp_stk, 15); mp = &tcp->tcp_closemp; SQUEUE_ENTER_ONE(connp->conn_sqp, mp, tcp_timewait_close, connp, NULL, SQ_FILL, SQTAG_TCP_TIMEWAIT); } mutex_enter(&tcp_time_wait->tcp_time_wait_lock); } if (tcp_time_wait->tcp_free_list != NULL) tcp_time_wait->tcp_free_list->tcp_in_free_list = B_TRUE; /* * If the time wait list is not empty and there is no timer running, * restart it. */ if ((tcp = tcp_time_wait->tcp_time_wait_head) != NULL && tcp_time_wait->tcp_time_wait_tid == 0) { hrtime_t firetime; /* shouldn't be necessary, but just in case */ if (tcp->tcp_time_wait_expire < now) tcp->tcp_time_wait_expire = now; firetime = TICK_TO_NSEC(tcp->tcp_time_wait_expire - now); /* This ensures that we won't wake up too often. */ firetime = MAX(TCP_TIME_WAIT_DELAY, firetime); tcp_time_wait->tcp_time_wait_tid = timeout_generic(CALLOUT_NORMAL, tcp_time_wait_collector, sqp, firetime, CALLOUT_TCP_RESOLUTION, CALLOUT_FLAG_ROUNDUP); } #ifdef DEBUG tcp_time_wait->tcp_time_wait_running = B_FALSE; #endif mutex_exit(&tcp_time_wait->tcp_time_wait_lock); } /* * tcp_time_wait_processing() handles processing of incoming packets when * the tcp_t is in the TIME_WAIT state. * * A TIME_WAIT tcp_t that has an associated open TCP end point (not in * detached state) is never put on the time wait list. */ void tcp_time_wait_processing(tcp_t *tcp, mblk_t *mp, uint32_t seg_seq, uint32_t seg_ack, int seg_len, tcpha_t *tcpha, ip_recv_attr_t *ira) { int32_t bytes_acked; int32_t gap; int32_t rgap; tcp_opt_t tcpopt; uint_t flags; uint32_t new_swnd = 0; conn_t *nconnp; conn_t *connp = tcp->tcp_connp; tcp_stack_t *tcps = tcp->tcp_tcps; BUMP_LOCAL(tcp->tcp_ibsegs); DTRACE_PROBE2(tcp__trace__recv, mblk_t *, mp, tcp_t *, tcp); flags = (unsigned int)tcpha->tha_flags & 0xFF; new_swnd = ntohs(tcpha->tha_win) << ((tcpha->tha_flags & TH_SYN) ? 0 : tcp->tcp_snd_ws); if (tcp->tcp_snd_ts_ok && !(tcpha->tha_flags & TH_RST)) { int options; if (tcp->tcp_snd_sack_ok) tcpopt.tcp = tcp; else tcpopt.tcp = NULL; options = tcp_parse_options(tcpha, &tcpopt); if (!(options & TCP_OPT_TSTAMP_PRESENT)) { DTRACE_TCP1(droppedtimestamp, tcp_t *, tcp); goto done; } else if (!tcp_paws_check(tcp, &tcpopt)) { tcp_xmit_ctl(NULL, tcp, tcp->tcp_snxt, tcp->tcp_rnxt, TH_ACK); goto done; } } gap = seg_seq - tcp->tcp_rnxt; rgap = tcp->tcp_rwnd - (gap + seg_len); if (gap < 0) { TCPS_BUMP_MIB(tcps, tcpInDataDupSegs); TCPS_UPDATE_MIB(tcps, tcpInDataDupBytes, (seg_len > -gap ? -gap : seg_len)); seg_len += gap; if (seg_len < 0 || (seg_len == 0 && !(flags & TH_FIN))) { if (flags & TH_RST) { goto done; } if ((flags & TH_FIN) && seg_len == -1) { /* * When TCP receives a duplicate FIN in * TIME_WAIT state, restart the 2 MSL timer. * See page 73 in RFC 793. Make sure this TCP * is already on the TIME_WAIT list. If not, * just restart the timer. */ if (TCP_IS_DETACHED(tcp)) { if (tcp_time_wait_remove(tcp, NULL) == B_TRUE) { tcp_time_wait_append(tcp); TCP_DBGSTAT(tcps, tcp_rput_time_wait); } } else { ASSERT(tcp != NULL); TCP_TIMER_RESTART(tcp, tcps->tcps_time_wait_interval); } tcp_xmit_ctl(NULL, tcp, tcp->tcp_snxt, tcp->tcp_rnxt, TH_ACK); goto done; } flags |= TH_ACK_NEEDED; seg_len = 0; goto process_ack; } /* Fix seg_seq, and chew the gap off the front. */ seg_seq = tcp->tcp_rnxt; } if ((flags & TH_SYN) && gap > 0 && rgap < 0) { /* * Make sure that when we accept the connection, pick * an ISS greater than (tcp_snxt + tcp_iss_incr/2) for the * old connection. * * The next ISS generated is equal to tcp_iss_incr_extra * + tcp_iss_incr/2 + other components depending on the * value of tcp_strong_iss. We pre-calculate the new * ISS here and compare with tcp_snxt to determine if * we need to make adjustment to tcp_iss_incr_extra. * * The above calculation is ugly and is a * waste of CPU cycles... */ uint32_t new_iss = tcps->tcps_iss_incr_extra; int32_t adj; ip_stack_t *ipst = tcps->tcps_netstack->netstack_ip; switch (tcps->tcps_strong_iss) { case 2: { /* Add time and MD5 components. */ uint32_t answer[4]; struct { uint32_t ports; in6_addr_t src; in6_addr_t dst; } arg; MD5_CTX context; mutex_enter(&tcps->tcps_iss_key_lock); context = tcps->tcps_iss_key; mutex_exit(&tcps->tcps_iss_key_lock); arg.ports = connp->conn_ports; /* We use MAPPED addresses in tcp_iss_init */ arg.src = connp->conn_laddr_v6; arg.dst = connp->conn_faddr_v6; MD5Update(&context, (uchar_t *)&arg, sizeof (arg)); MD5Final((uchar_t *)answer, &context); answer[0] ^= answer[1] ^ answer[2] ^ answer[3]; new_iss += (gethrtime() >> ISS_NSEC_SHT) + answer[0]; break; } case 1: /* Add time component and min random (i.e. 1). */ new_iss += (gethrtime() >> ISS_NSEC_SHT) + 1; break; default: /* Add only time component. */ new_iss += (uint32_t)gethrestime_sec() * tcps->tcps_iss_incr; break; } if ((adj = (int32_t)(tcp->tcp_snxt - new_iss)) > 0) { /* * New ISS not guaranteed to be tcp_iss_incr/2 * ahead of the current tcp_snxt, so add the * difference to tcp_iss_incr_extra. */ tcps->tcps_iss_incr_extra += adj; } /* * If tcp_clean_death() can not perform the task now, * drop the SYN packet and let the other side re-xmit. * Otherwise pass the SYN packet back in, since the * old tcp state has been cleaned up or freed. */ if (tcp_clean_death(tcp, 0) == -1) goto done; nconnp = ipcl_classify(mp, ira, ipst); if (nconnp != NULL) { TCP_STAT(tcps, tcp_time_wait_syn_success); /* Drops ref on nconnp */ tcp_reinput(nconnp, mp, ira, ipst); return; } goto done; } /* * rgap is the amount of stuff received out of window. A negative * value is the amount out of window. */ if (rgap < 0) { TCPS_BUMP_MIB(tcps, tcpInDataPastWinSegs); TCPS_UPDATE_MIB(tcps, tcpInDataPastWinBytes, -rgap); /* Fix seg_len and make sure there is something left. */ seg_len += rgap; if (seg_len <= 0) { if (flags & TH_RST) { goto done; } flags |= TH_ACK_NEEDED; seg_len = 0; goto process_ack; } } /* * Check whether we can update tcp_ts_recent. This test is from RFC * 7323, section 5.3. */ if (tcp->tcp_snd_ts_ok && !(flags & TH_RST) && TSTMP_GEQ(tcpopt.tcp_opt_ts_val, tcp->tcp_ts_recent) && SEQ_LEQ(seg_seq, tcp->tcp_rack)) { tcp->tcp_ts_recent = tcpopt.tcp_opt_ts_val; tcp->tcp_last_rcv_lbolt = ddi_get_lbolt64(); } if (seg_seq != tcp->tcp_rnxt && seg_len > 0) { /* Always ack out of order packets */ flags |= TH_ACK_NEEDED; seg_len = 0; } else if (seg_len > 0) { TCPS_BUMP_MIB(tcps, tcpInClosed); TCPS_BUMP_MIB(tcps, tcpInDataInorderSegs); TCPS_UPDATE_MIB(tcps, tcpInDataInorderBytes, seg_len); } if (flags & TH_RST) { (void) tcp_clean_death(tcp, 0); goto done; } if (flags & TH_SYN) { tcp_xmit_ctl("TH_SYN", tcp, seg_ack, seg_seq + 1, TH_RST|TH_ACK); /* * Do not delete the TCP structure if it is in * TIME_WAIT state. Refer to RFC 1122, 4.2.2.13. */ goto done; } process_ack: if (flags & TH_ACK) { bytes_acked = (int)(seg_ack - tcp->tcp_suna); if (bytes_acked <= 0) { if (bytes_acked == 0 && seg_len == 0 && new_swnd == tcp->tcp_swnd) TCPS_BUMP_MIB(tcps, tcpInDupAck); } else { /* Acks something not sent */ flags |= TH_ACK_NEEDED; } } if (flags & TH_ACK_NEEDED) { /* * Time to send an ack for some reason. */ tcp_xmit_ctl(NULL, tcp, tcp->tcp_snxt, tcp->tcp_rnxt, TH_ACK); } done: freemsg(mp); }