/* * Copyright (c) 2000-2022 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 * $FreeBSD: src/sys/netinet/tcp_input.c,v 1.107.2.16 2001/08/22 00:59:12 silby Exp $ */ /* * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce * support for mandatory and extensible security protections. This notice * is included in support of clause 2.2 (b) of the Apple Public License, * Version 2.0. */ #include "tcp_includes.h" #include #include #include #include #include #include #include /* for proc0 declaration */ #include #include #include #include #include #include #include /* before tcp_seq.h, for tcp_random18() */ #include #include #include #include #include #include #include #include #include #include #include #include /* for ICMP_BANDLIM */ #include #include /* for ICMP_BANDLIM */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if TCPDEBUG #include u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */ struct tcphdr tcp_savetcp; #endif /* TCPDEBUG */ #include #if IPSEC #include #include #include #endif /*IPSEC*/ #include #if MPTCP #include #include #include #endif /* MPTCP */ #include #include #define DBG_LAYER_BEG NETDBG_CODE(DBG_NETTCP, 0) #define DBG_LAYER_END NETDBG_CODE(DBG_NETTCP, 2) #define DBG_FNC_TCP_INPUT NETDBG_CODE(DBG_NETTCP, (3 << 8)) #define DBG_FNC_TCP_NEWCONN NETDBG_CODE(DBG_NETTCP, (7 << 8)) #define TCP_RTT_HISTORY_EXPIRE_TIME (60 * TCP_RETRANSHZ) #define TCP_RECV_THROTTLE_WIN (5 * TCP_RETRANSHZ) #define TCP_STRETCHACK_ENABLE_PKTCNT 2000 struct tcpstat tcpstat; SYSCTL_SKMEM_TCP_INT(OID_AUTO, flow_control_response, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_flow_control_response, 1, "Improved response to Flow-control events"); static int log_in_vain = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW | CTLFLAG_LOCKED, &log_in_vain, 0, "Log all incoming TCP connections"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, ack_strategy, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_ack_strategy, TCP_ACK_STRATEGY_MODERN, "Revised TCP ACK-strategy, avoiding stretch-ACK implementation"); static int blackhole = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW | CTLFLAG_LOCKED, &blackhole, 0, "Do not send RST when dropping refused connections"); /* TODO - remove once uTCP stopped using it */ SYSCTL_SKMEM_TCP_INT(OID_AUTO, aggressive_rcvwnd_inc, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_aggressive_rcvwnd_inc, 1, "Be more aggressive about increasing the receive-window."); SYSCTL_SKMEM_TCP_INT(OID_AUTO, delayed_ack, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_delack_enabled, 3, "Delay ACK to try and piggyback it onto a data packet"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, recvbg, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_recv_bg, 0, "Receive background"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, drop_synfin, CTLFLAG_RW | CTLFLAG_LOCKED, static int, drop_synfin, 1, "Drop TCP packets with SYN+FIN set"); SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "TCP Segment Reassembly Queue"); static int tcp_reass_overflows = 0; SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD | CTLFLAG_LOCKED, &tcp_reass_overflows, 0, "Global number of TCP segment reassembly queue overflows"); int tcp_reass_total_qlen = 0; SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, qlen, CTLFLAG_RD | CTLFLAG_LOCKED, &tcp_reass_total_qlen, 0, "Total number of TCP segments in reassembly queues"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, slowlink_wsize, CTLFLAG_RW | CTLFLAG_LOCKED, __private_extern__ int, slowlink_wsize, 8192, "Maximum advertised window size for slowlink"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, maxseg_unacked, CTLFLAG_RW | CTLFLAG_LOCKED, int, maxseg_unacked, 8, "Maximum number of outstanding segments left unacked"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, rfc3465, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_do_rfc3465, 1, ""); SYSCTL_SKMEM_TCP_INT(OID_AUTO, rfc3465_lim2, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_do_rfc3465_lim2, 1, "Appropriate bytes counting w/ L=2*SMSS"); int rtt_samples_per_slot = 20; int tcp_acc_iaj_high_thresh = ACC_IAJ_HIGH_THRESH; u_int32_t tcp_autorcvbuf_inc_shift = 3; SYSCTL_SKMEM_TCP_INT(OID_AUTO, recv_allowed_iaj, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_allowed_iaj, ALLOWED_IAJ, "Allowed inter-packet arrival jiter"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, doautorcvbuf, CTLFLAG_RW | CTLFLAG_LOCKED, u_int32_t, tcp_do_autorcvbuf, 1, "Enable automatic socket buffer tuning"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, autotunereorder, CTLFLAG_RW | CTLFLAG_LOCKED, u_int32_t, tcp_autotune_reorder, 1, "Enable automatic socket buffer tuning even when reordering is present"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, autorcvbufmax, CTLFLAG_RW | CTLFLAG_LOCKED | CTLFLAG_KERN, u_int32_t, tcp_autorcvbuf_max, 2 * 1024 * 1024, "Maximum receive socket buffer size"); int tcp_disable_access_to_stats = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, disable_access_to_stats, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_disable_access_to_stats, 0, "Disable access to tcpstat"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, challengeack_limit, CTLFLAG_RW | CTLFLAG_LOCKED, uint32_t, tcp_challengeack_limit, 10, "Maximum number of challenge ACKs per connection per second"); /* TO BE REMOVED */ SYSCTL_SKMEM_TCP_INT(OID_AUTO, do_rfc5961, CTLFLAG_RW | CTLFLAG_LOCKED, static int, tcp_do_rfc5961, 1, "Enable/Disable full RFC 5961 compliance"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, do_better_lr, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_do_better_lr, 1, "Improved TCP Loss Recovery"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, use_min_curr_rtt, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_use_min_curr_rtt, 1, "Use a min of k=4 RTT samples for congestion controllers"); SYSCTL_SKMEM_TCP_INT(OID_AUTO, awdl_rtobase, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_awdl_rtobase, 100, "Initial RTO for AWDL interface"); extern int tcp_acc_iaj_high; extern int tcp_acc_iaj_react_limit; extern int tcp_fin_timeout; uint8_t tcprexmtthresh = 3; u_int32_t tcp_now; struct timeval tcp_uptime; /* uptime when tcp_now was last updated */ /* Used to sychronize updates to tcp_now */ static LCK_GRP_DECLARE(tcp_uptime_mtx_grp, "tcpuptime"); LCK_SPIN_DECLARE(tcp_uptime_lock, &tcp_uptime_mtx_grp); struct inpcbhead tcb; #define tcb6 tcb /* for KAME src sync over BSD*'s */ struct inpcbinfo tcbinfo; static void tcp_dooptions(struct tcpcb *, u_char *, int, struct tcphdr *, struct tcpopt *); static void tcp_finalize_options(struct tcpcb *, struct tcpopt *, unsigned int); static void tcp_pulloutofband(struct socket *, struct tcphdr *, struct mbuf *, int); static void tcp_xmit_timer(struct tcpcb *, int, u_int32_t, tcp_seq); static inline unsigned int tcp_maxmtu(struct rtentry *); static inline int tcp_stretch_ack_enable(struct tcpcb *tp, int thflags); static inline void tcp_adaptive_rwtimo_check(struct tcpcb *, int); #if TRAFFIC_MGT static inline void compute_iaj(struct tcpcb *tp); static inline void compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj); #endif /* TRAFFIC_MGT */ static inline unsigned int tcp_maxmtu6(struct rtentry *); unsigned int get_maxmtu(struct rtentry *); static void tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sb, struct tcpopt *to, uint32_t tlen); void tcp_sbrcv_trim(struct tcpcb *tp, struct sockbuf *sb); static void tcp_sbsnd_trim(struct sockbuf *sbsnd); static inline void tcp_sbrcv_tstmp_check(struct tcpcb *tp); static inline void tcp_sbrcv_reserve(struct tcpcb *tp, struct sockbuf *sb, u_int32_t newsize, u_int32_t idealsize, u_int32_t rcvbuf_max); static void tcp_bad_rexmt_restore_state(struct tcpcb *tp, struct tcphdr *th); static void tcp_compute_rtt(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th); static void tcp_compute_rcv_rtt(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th); static void tcp_early_rexmt_check(struct tcpcb *tp, struct tcphdr *th); static void tcp_bad_rexmt_check(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to); /* * Constants used for resizing receive socket buffer * when timestamps are not supported */ #define TCPTV_RCVNOTS_QUANTUM 100 #define TCP_RCVNOTS_BYTELEVEL 204800 /* * Constants used for limiting early retransmits * to 10 per minute. */ #define TCP_EARLY_REXMT_WIN (60 * TCP_RETRANSHZ) /* 60 seconds */ #define TCP_EARLY_REXMT_LIMIT 10 #define log_in_vain_log( a ) { log a; } int tcp_rcvunackwin = TCPTV_UNACKWIN; int tcp_maxrcvidle = TCPTV_MAXRCVIDLE; SYSCTL_SKMEM_TCP_INT(OID_AUTO, rcvsspktcnt, CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_rcvsspktcnt, TCP_RCV_SS_PKTCOUNT, "packets to be seen before receiver stretches acks"); #define DELAY_ACK(tp, th) \ (CC_ALGO(tp)->delay_ack != NULL && CC_ALGO(tp)->delay_ack(tp, th)) static int tcp_dropdropablreq(struct socket *head); static void tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th); static void update_base_rtt(struct tcpcb *tp, uint32_t rtt); void tcp_set_background_cc(struct socket *so); void tcp_set_foreground_cc(struct socket *so); static void tcp_set_new_cc(struct socket *so, uint8_t cc_index); static void tcp_bwmeas_check(struct tcpcb *tp); #if TRAFFIC_MGT void reset_acc_iaj(struct tcpcb *tp) { tp->acc_iaj = 0; CLEAR_IAJ_STATE(tp); } static inline void update_iaj_state(struct tcpcb *tp, int size, int rst_size) { if (rst_size > 0) { tp->iaj_size = 0; } if (tp->iaj_size == 0 || size >= tp->iaj_size) { tp->iaj_size = size; tp->iaj_rcv_ts = tcp_now; tp->iaj_small_pkt = 0; } } /* For every 64-bit unsigned integer(v), this function will find the * largest 32-bit integer n such that (n*n <= v). This takes at most 32 iterations * irrespective of the value of v and does not involve multiplications. */ static inline uint32_t isqrt(uint64_t val) { uint32_t sqrt_cache[11] = {0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100}; uint64_t temp, g = 0, b = 1 << 31, bshft = 31; if (val <= 100) { for (g = 0; g <= 10; ++g) { if (sqrt_cache[g] > val) { g--; break; } else if (sqrt_cache[g] == val) { break; } } } else { do { temp = (((g << 1) + b) << (bshft--)); if (val >= temp) { g += b; val -= temp; } b >>= 1; } while (b > 0 && val > 0); } return (uint32_t)g; } static inline void compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj) { /* When accumulated IAJ reaches MAX_ACC_IAJ in milliseconds, * throttle the receive window to a minimum of MIN_IAJ_WIN packets */ #define MAX_ACC_IAJ (tcp_acc_iaj_high_thresh + tcp_acc_iaj_react_limit) #define IAJ_DIV_SHIFT 4 #define IAJ_ROUNDUP_CONST (1 << (IAJ_DIV_SHIFT - 1)) uint32_t allowed_iaj, acc_iaj = 0; /* Using 64-bit storage for the inter-arrival jitter deviation, * to avoid accidentally rolling over if the inter-arrival time exceeds 62 seconds. */ int64_t mean, temp, cur_iaj_dev; cur_iaj_dev = (cur_iaj - tp->avg_iaj); /* Allow a jitter of "allowed_iaj" milliseconds. Some connections * may have a constant jitter more than that. We detect this by * using standard deviation. */ allowed_iaj = tp->avg_iaj + tp->std_dev_iaj; if (allowed_iaj < tcp_allowed_iaj) { allowed_iaj = tcp_allowed_iaj; } /* Initially when the connection starts, the senders congestion * window is small. During this period we avoid throttling a * connection because we do not have a good starting point for * allowed_iaj. IAJ_IGNORE_PKTCNT is used to quietly gloss over * the first few packets. */ if (tp->iaj_pktcnt > IAJ_IGNORE_PKTCNT) { if (cur_iaj <= allowed_iaj) { if (tp->acc_iaj >= 2) { acc_iaj = tp->acc_iaj - 2; } else { acc_iaj = 0; } } else { acc_iaj = tp->acc_iaj + (cur_iaj - allowed_iaj); } if (acc_iaj > MAX_ACC_IAJ) { acc_iaj = MAX_ACC_IAJ; } tp->acc_iaj = acc_iaj; } /* Compute weighted average where the history has a weight of * 15 out of 16 and the current value has a weight of 1 out of 16. * This will make the short-term measurements have more weight. * * The addition of 8 will help to round-up the value * instead of round-down */ tp->avg_iaj = (((tp->avg_iaj << IAJ_DIV_SHIFT) - tp->avg_iaj) + cur_iaj + IAJ_ROUNDUP_CONST) >> IAJ_DIV_SHIFT; /* Compute Root-mean-square of deviation where mean is a weighted * average as described above. */ temp = tp->std_dev_iaj * tp->std_dev_iaj; mean = (((temp << IAJ_DIV_SHIFT) - temp) + (cur_iaj_dev * cur_iaj_dev) + IAJ_ROUNDUP_CONST) >> IAJ_DIV_SHIFT; tp->std_dev_iaj = isqrt(mean); DTRACE_TCP3(iaj, struct tcpcb *, tp, uint32_t, cur_iaj, uint32_t, allowed_iaj); return; } static inline void compute_iaj(struct tcpcb *tp) { compute_iaj_meat(tp, (tcp_now - tp->iaj_rcv_ts)); } #endif /* TRAFFIC_MGT */ /* * Perform rate limit check per connection per second * tp->t_challengeack_last is the last_time diff was greater than 1sec * tp->t_challengeack_count is the number of ACKs sent (within 1sec) * Return TRUE if we shouldn't send the ACK due to rate limitation * Return FALSE if it is still ok to send challenge ACK */ static boolean_t tcp_is_ack_ratelimited(struct tcpcb *tp) { boolean_t ret = TRUE; uint32_t now = tcp_now; int32_t diff = 0; diff = timer_diff(now, 0, tp->t_challengeack_last, 0); /* If it is first time or diff > 1000ms, * update the challengeack_last and reset the * current count of ACKs */ if (tp->t_challengeack_last == 0 || diff >= 1000) { tp->t_challengeack_last = now; tp->t_challengeack_count = 0; ret = FALSE; } else if (tp->t_challengeack_count < tcp_challengeack_limit) { ret = FALSE; } /* Careful about wrap-around */ if (ret == FALSE && (tp->t_challengeack_count + 1 > 0)) { tp->t_challengeack_count++; } return ret; } /* Check if enough amount of data has been acknowledged since * bw measurement was started */ static void tcp_bwmeas_check(struct tcpcb *tp) { int32_t bw_meas_bytes; uint32_t bw, bytes, elapsed_time; if (SEQ_LEQ(tp->snd_una, tp->t_bwmeas->bw_start)) { return; } bw_meas_bytes = tp->snd_una - tp->t_bwmeas->bw_start; if ((tp->t_flagsext & TF_BWMEAS_INPROGRESS) && bw_meas_bytes >= (int32_t)(tp->t_bwmeas->bw_size)) { bytes = bw_meas_bytes; elapsed_time = tcp_now - tp->t_bwmeas->bw_ts; if (elapsed_time > 0) { bw = bytes / elapsed_time; if (bw > 0) { if (tp->t_bwmeas->bw_sndbw > 0) { tp->t_bwmeas->bw_sndbw = (((tp->t_bwmeas->bw_sndbw << 3) - tp->t_bwmeas->bw_sndbw) + bw) >> 3; } else { tp->t_bwmeas->bw_sndbw = bw; } /* Store the maximum value */ if (tp->t_bwmeas->bw_sndbw_max == 0) { tp->t_bwmeas->bw_sndbw_max = tp->t_bwmeas->bw_sndbw; } else { tp->t_bwmeas->bw_sndbw_max = max(tp->t_bwmeas->bw_sndbw, tp->t_bwmeas->bw_sndbw_max); } } } tp->t_flagsext &= ~(TF_BWMEAS_INPROGRESS); } } static int tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m, struct ifnet *ifp, int *dowakeup) { struct tseg_qent *q; struct tseg_qent *p = NULL; struct tseg_qent *nq; struct tseg_qent *te = NULL; struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; int flags = 0; uint32_t qlimit; boolean_t cell = IFNET_IS_CELLULAR(ifp); boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp)); boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp)); boolean_t dsack_set = FALSE; /* * If the reassembly queue already has entries or if we are going * to add a new one, then the connection has reached a loss state. * Reset the stretch-ack algorithm at this point. */ tcp_reset_stretch_ack(tp); tp->t_forced_acks = TCP_FORCED_ACKS_COUNT; #if TRAFFIC_MGT if (tp->acc_iaj > 0) { reset_acc_iaj(tp); } #endif /* TRAFFIC_MGT */ if (th->th_seq != tp->rcv_nxt) { struct mbuf *tmp = m; while (tmp != NULL) { if (mbuf_class_under_pressure(tmp)) { m_freem(m); tcp_reass_overflows++; tcpstat.tcps_rcvmemdrop++; *tlenp = 0; return 0; } tmp = tmp->m_next; } } /* * Limit the number of segments in the reassembly queue to prevent * holding on to too many segments (and thus running out of mbufs). * Make sure to let the missing segment through which caused this * queue. Always keep one global queue entry spare to be able to * process the missing segment. */ qlimit = min(max(100, so->so_rcv.sb_hiwat >> 10), (tcp_autorcvbuf_max >> 10)); if (th->th_seq != tp->rcv_nxt && (tp->t_reassqlen + 1) >= qlimit) { tcp_reass_overflows++; tcpstat.tcps_rcvmemdrop++; m_freem(m); *tlenp = 0; return 0; } /* Allocate a new queue entry. If we can't, just drop the pkt. XXX */ te = zalloc_flags(tcp_reass_zone, Z_WAITOK | Z_NOFAIL); tp->t_reassqlen++; OSIncrementAtomic(&tcp_reass_total_qlen); /* * Find a segment which begins after this one does. */ LIST_FOREACH(q, &tp->t_segq, tqe_q) { if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) { break; } p = q; } /* * If there is a preceding segment, it may provide some of * our data already. If so, drop the data from the incoming * segment. If it provides all of our data, drop us. */ if (p != NULL) { int i; /* conversion to int (in i) handles seq wraparound */ i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; if (i > 0) { if (i > 1) { /* * Note duplicate data sequnce numbers * to report in DSACK option */ tp->t_dsack_lseq = th->th_seq; tp->t_dsack_rseq = th->th_seq + min(i, *tlenp); /* * Report only the first part of partial/ * non-contiguous duplicate sequence space */ dsack_set = TRUE; } if (i >= *tlenp) { tcpstat.tcps_rcvduppack++; tcpstat.tcps_rcvdupbyte += *tlenp; if (nstat_collect) { nstat_route_rx(inp->inp_route.ro_rt, 1, *tlenp, NSTAT_RX_FLAG_DUPLICATE); INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, *tlenp); tp->t_stat.rxduplicatebytes += *tlenp; inp_set_activity_bitmap(inp); } m_freem(m); zfree(tcp_reass_zone, te); te = NULL; tp->t_reassqlen--; OSDecrementAtomic(&tcp_reass_total_qlen); /* * Try to present any queued data * at the left window edge to the user. * This is needed after the 3-WHS * completes. */ goto present; } m_adj(m, i); *tlenp -= i; th->th_seq += i; } } if (th->th_seq != tp->rcv_nxt) { tp->t_rcvoopack++; tcpstat.tcps_rcvoopack++; tcpstat.tcps_rcvoobyte += *tlenp; if (nstat_collect) { tp->t_stat.rxoutoforderbytes += *tlenp; } } if (nstat_collect) { nstat_route_rx(inp->inp_route.ro_rt, 1, *tlenp, NSTAT_RX_FLAG_OUT_OF_ORDER); INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, *tlenp); inp_set_activity_bitmap(inp); } /* * While we overlap succeeding segments trim them or, * if they are completely covered, dequeue them. */ while (q) { int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; if (i <= 0) { break; } /* * Report only the first part of partial/non-contiguous * duplicate segment in dsack option. The variable * dsack_set will be true if a previous entry has some of * the duplicate sequence space. */ if (i > 1 && !dsack_set) { if (tp->t_dsack_lseq == 0) { tp->t_dsack_lseq = q->tqe_th->th_seq; tp->t_dsack_rseq = tp->t_dsack_lseq + min(i, q->tqe_len); } else { /* * this segment overlaps data in multple * entries in the reassembly queue, move * the right sequence number further. */ tp->t_dsack_rseq = tp->t_dsack_rseq + min(i, q->tqe_len); } } if (i < q->tqe_len) { q->tqe_th->th_seq += i; q->tqe_len -= i; m_adj(q->tqe_m, i); break; } nq = LIST_NEXT(q, tqe_q); LIST_REMOVE(q, tqe_q); tp->t_reassq_mbcnt -= _MSIZE + (q->tqe_m->m_flags & M_EXT) ? q->tqe_m->m_ext.ext_size : 0; m_freem(q->tqe_m); zfree(tcp_reass_zone, q); tp->t_reassqlen--; OSDecrementAtomic(&tcp_reass_total_qlen); q = nq; } /* Insert the new segment queue entry into place. */ te->tqe_m = m; te->tqe_th = th; te->tqe_len = *tlenp; tp->t_reassq_mbcnt += _MSIZE + (m->m_flags & M_EXT) ? m->m_ext.ext_size : 0; if (p == NULL) { LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); } else { LIST_INSERT_AFTER(p, te, tqe_q); } present: /* * Present data to user, advancing rcv_nxt through * completed sequence space. */ if (!TCPS_HAVEESTABLISHED(tp->t_state)) { return 0; } q = LIST_FIRST(&tp->t_segq); if (!q || q->tqe_th->th_seq != tp->rcv_nxt) { return 0; } /* * If there is already another thread doing reassembly for this * connection, it is better to let it finish the job -- * (radar 16316196) */ if (tp->t_flagsext & TF_REASS_INPROG) { return 0; } tp->t_flagsext |= TF_REASS_INPROG; /* lost packet was recovered, so ooo data can be returned */ tcpstat.tcps_recovered_pkts++; do { tp->rcv_nxt += q->tqe_len; flags = q->tqe_th->th_flags & TH_FIN; LIST_REMOVE(q, tqe_q); tp->t_reassq_mbcnt -= _MSIZE + (q->tqe_m->m_flags & M_EXT) ? q->tqe_m->m_ext.ext_size : 0; if (so->so_state & SS_CANTRCVMORE) { m_freem(q->tqe_m); } else { so_recv_data_stat(so, q->tqe_m, 0); /* XXXX */ if (q->tqe_th->th_flags & TH_PUSH) { tp->t_flagsext |= TF_LAST_IS_PSH; } else { tp->t_flagsext &= ~TF_LAST_IS_PSH; } if (sbappendstream_rcvdemux(so, q->tqe_m)) { *dowakeup = 1; } } zfree(tcp_reass_zone, q); tp->t_reassqlen--; OSDecrementAtomic(&tcp_reass_total_qlen); q = LIST_FIRST(&tp->t_segq); } while (q && q->tqe_th->th_seq == tp->rcv_nxt); tp->t_flagsext &= ~TF_REASS_INPROG; if ((inp->inp_vflag & INP_IPV6) != 0) { KERNEL_DEBUG(DBG_LAYER_BEG, ((inp->inp_fport << 16) | inp->inp_lport), (((inp->in6p_laddr.s6_addr16[0] & 0xffff) << 16) | (inp->in6p_faddr.s6_addr16[0] & 0xffff)), 0, 0, 0); } else { KERNEL_DEBUG(DBG_LAYER_BEG, ((inp->inp_fport << 16) | inp->inp_lport), (((inp->inp_laddr.s_addr & 0xffff) << 16) | (inp->inp_faddr.s_addr & 0xffff)), 0, 0, 0); } return flags; } /* * Reduce congestion window -- used when ECN is seen or when a tail loss * probe recovers the last packet. */ static void tcp_reduce_congestion_window(struct tcpcb *tp) { /* * If the current tcp cc module has * defined a hook for tasks to run * before entering FR, call it */ if (CC_ALGO(tp)->pre_fr != NULL) { CC_ALGO(tp)->pre_fr(tp); } ENTER_FASTRECOVERY(tp); if (tp->t_flags & TF_SENTFIN) { tp->snd_recover = tp->snd_max - 1; } else { tp->snd_recover = tp->snd_max; } tp->t_timer[TCPT_REXMT] = 0; tp->t_timer[TCPT_PTO] = 0; tp->t_rtttime = 0; if (tp->t_flagsext & TF_CWND_NONVALIDATED) { tcp_cc_adjust_nonvalidated_cwnd(tp); } else { tp->snd_cwnd = tp->snd_ssthresh + tp->t_maxseg * tcprexmtthresh; } } /* * This function is called upon reception of data on a socket. It's purpose is * to handle the adaptive keepalive timers that monitor whether the connection * is making progress. First the adaptive read-timer, second the TFO probe-timer. * * The application wants to get an event if there is a stall during read. * Set the initial keepalive timeout to be equal to twice RTO. * * If the outgoing interface is in marginal conditions, we need to * enable read probes for that too. */ static inline void tcp_adaptive_rwtimo_check(struct tcpcb *tp, int tlen) { struct ifnet *outifp = tp->t_inpcb->inp_last_outifp; if ((tp->t_adaptive_rtimo > 0 || (outifp != NULL && (outifp->if_eflags & IFEF_PROBE_CONNECTIVITY))) && tlen > 0 && tp->t_state == TCPS_ESTABLISHED) { tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, (TCP_REXMTVAL(tp) << 1)); tp->t_flagsext |= TF_DETECT_READSTALL; tp->t_rtimo_probes = 0; } } inline void tcp_keepalive_reset(struct tcpcb *tp) { tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_CONN_KEEPIDLE(tp)); tp->t_flagsext &= ~(TF_DETECT_READSTALL); tp->t_rtimo_probes = 0; } void tcp_set_finwait_timeout(struct tcpcb *tp) { /* * Starting the TCPT_2MSL timer is contrary to the * specification, but if we don't get a FIN * we'll hang forever. */ ASSERT(tp->t_state == TCPS_FIN_WAIT_2); ASSERT((tp->t_inpcb->inp_socket->so_state & (SS_CANTRCVMORE)) == SS_CANTRCVMORE); if (tcp_fin_timeout > 0 && tcp_fin_timeout < TCP_CONN_MAXIDLE(tp)) { tp->t_timer[TCPT_2MSL] = OFFSET_FROM_START(tp, tcp_fin_timeout); } else { tp->t_timer[TCPT_2MSL] = OFFSET_FROM_START(tp, TCP_CONN_MAXIDLE(tp)); } } /* * TCP input routine, follows pages 65-76 of the * protocol specification dated September, 1981 very closely. */ int tcp6_input(struct mbuf **mp, int *offp, int proto) { #pragma unused(proto) struct mbuf *m = *mp; uint32_t ia6_flags; struct ifnet *ifp = m->m_pkthdr.rcvif; IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), return IPPROTO_DONE); /* Expect 32-bit aligned data pointer on strict-align platforms */ MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); /* * draft-itojun-ipv6-tcp-to-anycast * better place to put this in? */ if (ip6_getdstifaddr_info(m, NULL, &ia6_flags) == 0) { if (ia6_flags & IN6_IFF_ANYCAST) { struct ip6_hdr *ip6; ip6 = mtod(m, struct ip6_hdr *); icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, (int)((caddr_t)&ip6->ip6_dst - (caddr_t)ip6)); IF_TCP_STATINC(ifp, icmp6unreach); return IPPROTO_DONE; } } tcp_input(m, *offp); return IPPROTO_DONE; } static void tcp_sbrcv_reserve(struct tcpcb *tp, struct sockbuf *sbrcv, u_int32_t newsize, u_int32_t idealsize, u_int32_t rcvbuf_max) { /* newsize should not exceed max */ newsize = min(newsize, rcvbuf_max); /* The receive window scale negotiated at the * beginning of the connection will also set a * limit on the socket buffer size */ newsize = min(newsize, TCP_MAXWIN << tp->rcv_scale); /* Set new socket buffer size */ if (newsize > sbrcv->sb_hiwat && (sbreserve(sbrcv, newsize) == 1)) { sbrcv->sb_idealsize = min(max(sbrcv->sb_idealsize, (idealsize != 0) ? idealsize : newsize), rcvbuf_max); /* Again check the limit set by the advertised * window scale */ sbrcv->sb_idealsize = min(sbrcv->sb_idealsize, TCP_MAXWIN << tp->rcv_scale); } } /* * This function is used to grow a receive socket buffer. It * will take into account system-level memory usage and the * bandwidth available on the link to make a decision. */ static void tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sbrcv, struct tcpopt *to, uint32_t pktlen) { struct socket *so = sbrcv->sb_so; /* * Do not grow the receive socket buffer if * - auto resizing is disabled, globally or on this socket * - the high water mark already reached the maximum * - the stream is in background and receive side is being * throttled */ if (tcp_do_autorcvbuf == 0 || (sbrcv->sb_flags & SB_AUTOSIZE) == 0 || sbrcv->sb_hiwat >= tcp_autorcvbuf_max || (tp->t_flagsext & TF_RECV_THROTTLE) || (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED) || (!tcp_autotune_reorder && !LIST_EMPTY(&tp->t_segq))) { /* Can not resize the socket buffer, just return */ goto out; } if (!TSTMP_SUPPORTED(tp)) { /* * Timestamp option is not supported on this connection, * use receiver's RTT. Socket buffer grows based on the * BDP of the link. */ if (TSTMP_GEQ(tcp_now, tp->rfbuf_ts + (tp->rcv_srtt >> TCP_RTT_SHIFT))) { tp->rfbuf_cnt += pktlen; if (tp->rfbuf_cnt > tp->rfbuf_space) { int32_t rcvbuf_inc; uint32_t idealsize; /* * Increase receive-buffer aggressively if we * received more than 150% of what was received * in the previous round. Because, that means * the sender is in TCP slow-start and so * we need to give it more space to not be * limiting the sender with a small receive-window. */ if (tp->rfbuf_cnt > tp->rfbuf_space + (tp->rfbuf_space >> 1)) { rcvbuf_inc = (tp->rfbuf_cnt << 2) - sbrcv->sb_hiwat; idealsize = (tp->rfbuf_cnt << 2); } else { rcvbuf_inc = (tp->rfbuf_cnt << 1) - sbrcv->sb_hiwat; idealsize = (tp->rfbuf_cnt << 1); } if (rcvbuf_inc > 0) { rcvbuf_inc = (rcvbuf_inc / tp->t_maxseg) * tp->t_maxseg; tcp_sbrcv_reserve(tp, sbrcv, sbrcv->sb_hiwat + rcvbuf_inc, idealsize, tcp_autorcvbuf_max); tp->rfbuf_space = tp->rfbuf_cnt; } } goto out; } else { tp->rfbuf_cnt += pktlen; return; } } else if (to->to_tsecr != 0) { /* * If the timestamp shows that one RTT has * completed, we can stop counting the * bytes. Here we consider increasing * the socket buffer if the bandwidth measured in * last rtt, is more than half of sb_hiwat, this will * help to scale the buffer according to the bandwidth * on the link. */ if (TSTMP_GEQ(to->to_tsecr, tp->rfbuf_ts)) { tp->rfbuf_cnt += pktlen; if (tp->rfbuf_cnt > tp->rfbuf_space) { int32_t rcvbuf_inc; uint32_t idealsize; if (tp->rfbuf_cnt > tp->rfbuf_space + (tp->rfbuf_space >> 1)) { rcvbuf_inc = (tp->rfbuf_cnt << 2) - sbrcv->sb_hiwat; idealsize = (tp->rfbuf_cnt << 2); } else { rcvbuf_inc = (tp->rfbuf_cnt << 1) - sbrcv->sb_hiwat; idealsize = (tp->rfbuf_cnt << 1); } tp->rfbuf_space = tp->rfbuf_cnt; if (rcvbuf_inc > 0) { rcvbuf_inc = (rcvbuf_inc / tp->t_maxseg) * tp->t_maxseg; tcp_sbrcv_reserve(tp, sbrcv, sbrcv->sb_hiwat + rcvbuf_inc, idealsize, tcp_autorcvbuf_max); } } /* Measure instantaneous receive bandwidth */ if (tp->t_bwmeas != NULL && tp->rfbuf_cnt > 0 && TSTMP_GT(tcp_now, tp->rfbuf_ts)) { u_int32_t rcv_bw; rcv_bw = tp->rfbuf_cnt / (int)(tcp_now - tp->rfbuf_ts); if (tp->t_bwmeas->bw_rcvbw_max == 0) { tp->t_bwmeas->bw_rcvbw_max = rcv_bw; } else { tp->t_bwmeas->bw_rcvbw_max = max( tp->t_bwmeas->bw_rcvbw_max, rcv_bw); } } goto out; } else { tp->rfbuf_cnt += pktlen; return; } } out: /* Restart the measurement */ tp->rfbuf_ts = tcp_now; tp->rfbuf_cnt = 0; return; } /* This function will trim the excess space added to the socket buffer * to help a slow-reading app. The ideal-size of a socket buffer depends * on the link bandwidth or it is set by an application and we aim to * reach that size. */ void tcp_sbrcv_trim(struct tcpcb *tp, struct sockbuf *sbrcv) { if (tcp_do_autorcvbuf == 1 && sbrcv->sb_idealsize > 0 && sbrcv->sb_hiwat > sbrcv->sb_idealsize) { int32_t trim; /* compute the difference between ideal and current sizes */ u_int32_t diff = sbrcv->sb_hiwat - sbrcv->sb_idealsize; /* Compute the maximum advertised window for * this connection. */ u_int32_t advwin = tp->rcv_adv - tp->rcv_nxt; /* How much can we trim the receive socket buffer? * 1. it can not be trimmed beyond the max rcv win advertised * 2. if possible, leave 1/16 of bandwidth*delay to * avoid closing the win completely */ u_int32_t leave = max(advwin, (sbrcv->sb_idealsize >> 4)); /* Sometimes leave can be zero, in that case leave at least * a few segments worth of space. */ if (leave == 0) { leave = tp->t_maxseg << tcp_autorcvbuf_inc_shift; } trim = sbrcv->sb_hiwat - (sbrcv->sb_cc + leave); trim = imin(trim, (int32_t)diff); if (trim > 0) { sbreserve(sbrcv, (sbrcv->sb_hiwat - trim)); } } } /* We may need to trim the send socket buffer size for two reasons: * 1. if the rtt seen on the connection is climbing up, we do not * want to fill the buffers any more. * 2. if the congestion win on the socket backed off, there is no need * to hold more mbufs for that connection than what the cwnd will allow. */ void tcp_sbsnd_trim(struct sockbuf *sbsnd) { if (((sbsnd->sb_flags & (SB_AUTOSIZE | SB_TRIM)) == (SB_AUTOSIZE | SB_TRIM)) && (sbsnd->sb_idealsize > 0) && (sbsnd->sb_hiwat > sbsnd->sb_idealsize)) { u_int32_t trim = 0; if (sbsnd->sb_cc <= sbsnd->sb_idealsize) { trim = sbsnd->sb_hiwat - sbsnd->sb_idealsize; } else { trim = sbsnd->sb_hiwat - sbsnd->sb_cc; } sbreserve(sbsnd, (sbsnd->sb_hiwat - trim)); } if (sbsnd->sb_hiwat <= sbsnd->sb_idealsize) { sbsnd->sb_flags &= ~(SB_TRIM); } } /* * If timestamp option was not negotiated on this connection * and this connection is on the receiving side of a stream * then we can not measure the delay on the link accurately. * Instead of enabling automatic receive socket buffer * resizing, just give more space to the receive socket buffer. */ static inline void tcp_sbrcv_tstmp_check(struct tcpcb *tp) { struct socket *so = tp->t_inpcb->inp_socket; u_int32_t newsize = 2 * tcp_recvspace; struct sockbuf *sbrcv = &so->so_rcv; if ((tp->t_flags & (TF_REQ_TSTMP | TF_RCVD_TSTMP)) != (TF_REQ_TSTMP | TF_RCVD_TSTMP) && (sbrcv->sb_flags & SB_AUTOSIZE) != 0) { tcp_sbrcv_reserve(tp, sbrcv, newsize, 0, newsize); } } /* A receiver will evaluate the flow of packets on a connection * to see if it can reduce ack traffic. The receiver will start * stretching acks if all of the following conditions are met: * 1. tcp_delack_enabled is set to 3 * 2. If the bytes received in the last 100ms is greater than a threshold * defined by maxseg_unacked * 3. If the connection has not been idle for tcp_maxrcvidle period. * 4. If the connection has seen enough packets to let the slow-start * finish after connection establishment or after some packet loss. * * The receiver will stop stretching acks if there is congestion/reordering * as indicated by packets on reassembly queue or an ECN. If the delayed-ack * timer fires while stretching acks, it means that the packet flow has gone * below the threshold defined by maxseg_unacked and the receiver will stop * stretching acks. The receiver gets no indication when slow-start is completed * or when the connection reaches an idle state. That is why we use * tcp_rcvsspktcnt to cover slow-start and tcp_maxrcvidle to identify idle * state. */ static inline int tcp_stretch_ack_enable(struct tcpcb *tp, int thflags) { if (tp->rcv_by_unackwin >= (maxseg_unacked * tp->t_maxseg) && TSTMP_GEQ(tp->rcv_unackwin, tcp_now)) { tp->t_flags |= TF_STREAMING_ON; } else { tp->t_flags &= ~TF_STREAMING_ON; } /* If there has been an idle time, reset streaming detection */ if (TSTMP_GT(tcp_now, tp->rcv_unackwin + tcp_maxrcvidle)) { tp->t_flags &= ~TF_STREAMING_ON; } /* * If there are flags other than TH_ACK set, reset streaming * detection */ if (thflags & ~TH_ACK) { tp->t_flags &= ~TF_STREAMING_ON; } if (tp->t_flagsext & TF_DISABLE_STRETCHACK) { if (tp->rcv_nostrack_pkts >= TCP_STRETCHACK_ENABLE_PKTCNT) { tp->t_flagsext &= ~TF_DISABLE_STRETCHACK; tp->rcv_nostrack_pkts = 0; tp->rcv_nostrack_ts = 0; } else { tp->rcv_nostrack_pkts++; } } if (!(tp->t_flagsext & (TF_NOSTRETCHACK | TF_DISABLE_STRETCHACK)) && (tp->t_flags & TF_STREAMING_ON) && (!(tp->t_flagsext & TF_RCVUNACK_WAITSS) || (tp->rcv_waitforss >= tcp_rcvsspktcnt))) { return 1; } return 0; } /* * Reset the state related to stretch-ack algorithm. This will make * the receiver generate an ack every other packet. The receiver * will start re-evaluating the rate at which packets come to decide * if it can benefit by lowering the ack traffic. */ void tcp_reset_stretch_ack(struct tcpcb *tp) { tp->t_flags &= ~(TF_STRETCHACK | TF_STREAMING_ON); tp->rcv_by_unackwin = 0; tp->rcv_by_unackhalfwin = 0; tp->rcv_unackwin = tcp_now + tcp_rcvunackwin; /* * When there is packet loss or packet re-ordering or CWR due to * ECN, the sender's congestion window is reduced. In these states, * generate an ack for every other packet for some time to allow * the sender's congestion window to grow. */ tp->t_flagsext |= TF_RCVUNACK_WAITSS; tp->rcv_waitforss = 0; } /* * The last packet was a retransmission, check if this ack * indicates that the retransmission was spurious. * * If the connection supports timestamps, we could use it to * detect if the last retransmit was not needed. Otherwise, * we check if the ACK arrived within RTT/2 window, then it * was a mistake to do the retransmit in the first place. * * This function will return 1 if it is a spurious retransmit, * 0 otherwise. */ int tcp_detect_bad_rexmt(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, u_int32_t rxtime) { int32_t tdiff, bad_rexmt_win; bad_rexmt_win = (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); /* If the ack has ECN CE bit, then cwnd has to be adjusted */ if ((TCP_ACC_ECN_ON(tp) && tp->t_delta_ce_packets > 0) || (TCP_ECN_ENABLED(tp) && (th->th_flags & TH_ECE))) { return 0; } if (TSTMP_SUPPORTED(tp)) { if (rxtime > 0 && (to->to_flags & TOF_TS) && to->to_tsecr != 0 && TSTMP_LT(to->to_tsecr, rxtime)) { return 1; } } else { if ((tp->t_rxtshift == 1 || (tp->t_flagsext & TF_SENT_TLPROBE)) && rxtime > 0) { tdiff = (int32_t)(tcp_now - rxtime); if (tdiff < bad_rexmt_win) { return 1; } } } return 0; } /* * Restore congestion window state if a spurious timeout * was detected. */ static void tcp_bad_rexmt_restore_state(struct tcpcb *tp, struct tcphdr *th) { if (TSTMP_SUPPORTED(tp)) { u_int32_t fsize, acked; fsize = tp->snd_max - th->th_ack; acked = BYTES_ACKED(th, tp); /* * Implement bad retransmit recovery as * described in RFC 4015. */ tp->snd_ssthresh = tp->snd_ssthresh_prev; /* Initialize cwnd to the initial window */ if (CC_ALGO(tp)->cwnd_init != NULL) { CC_ALGO(tp)->cwnd_init(tp); } tp->snd_cwnd = fsize + min(acked, tp->snd_cwnd); } else { tp->snd_cwnd = tp->snd_cwnd_prev; tp->snd_ssthresh = tp->snd_ssthresh_prev; if (tp->t_flags & TF_WASFRECOVERY) { ENTER_FASTRECOVERY(tp); } /* Do not use the loss flight size in this case */ tp->t_lossflightsize = 0; } tp->snd_cwnd = max(tp->snd_cwnd, tcp_initial_cwnd(tp)); tp->snd_recover = tp->snd_recover_prev; tp->snd_nxt = tp->snd_max; /* Fix send socket buffer to reflect the change in cwnd */ tcp_bad_rexmt_fix_sndbuf(tp); /* * This RTT might reflect the extra delay induced * by the network. Skip using this sample for RTO * calculation and mark the connection so we can * recompute RTT when the next eligible sample is * found. */ tp->t_flagsext |= TF_RECOMPUTE_RTT; tp->t_badrexmt_time = tcp_now; tp->t_rtttime = 0; } /* * If the previous packet was sent in retransmission timer, and it was * not needed, then restore the congestion window to the state before that * transmission. * * If the last packet was sent in tail loss probe timeout, check if that * recovered the last packet. If so, that will indicate a real loss and * the congestion window needs to be lowered. */ static void tcp_bad_rexmt_check(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) { if (tp->t_rxtshift > 0 && tcp_detect_bad_rexmt(tp, th, to, tp->t_rxtstart)) { ++tcpstat.tcps_sndrexmitbad; tcp_bad_rexmt_restore_state(tp, th); tcp_ccdbg_trace(tp, th, TCP_CC_BAD_REXMT_RECOVERY); } else if ((tp->t_flagsext & TF_SENT_TLPROBE) && tp->t_tlphighrxt > 0 && SEQ_GEQ(th->th_ack, tp->t_tlphighrxt) && !tcp_detect_bad_rexmt(tp, th, to, tp->t_tlpstart)) { /* * The tail loss probe recovered the last packet and * we need to adjust the congestion window to take * this loss into account. */ ++tcpstat.tcps_tlp_recoverlastpkt; if (!IN_FASTRECOVERY(tp)) { tcp_reduce_congestion_window(tp); EXIT_FASTRECOVERY(tp); } tcp_ccdbg_trace(tp, th, TCP_CC_TLP_RECOVER_LASTPACKET); } else if (tcp_rxtseg_detect_bad_rexmt(tp, th->th_ack)) { /* * All of the retransmitted segments were duplicated, this * can be an indication of bad fast retransmit. */ tcpstat.tcps_dsack_badrexmt++; tcp_bad_rexmt_restore_state(tp, th); tcp_ccdbg_trace(tp, th, TCP_CC_DSACK_BAD_REXMT); tcp_rxtseg_clean(tp); } tp->t_flagsext &= ~(TF_SENT_TLPROBE); tp->t_tlphighrxt = 0; tp->t_tlpstart = 0; /* * check if the latest ack was for a segment sent during PMTU * blackhole detection. If the timestamp on the ack is before * PMTU blackhole detection, then revert the size of the max * segment to previous size. */ if (tp->t_rxtshift > 0 && (tp->t_flags & TF_BLACKHOLE) && tp->t_pmtud_start_ts > 0 && TSTMP_SUPPORTED(tp)) { if ((to->to_flags & TOF_TS) && to->to_tsecr != 0 && TSTMP_LT(to->to_tsecr, tp->t_pmtud_start_ts)) { tcp_pmtud_revert_segment_size(tp); } } if (tp->t_pmtud_start_ts > 0) { tp->t_pmtud_start_ts = 0; } tp->t_pmtud_lastseg_size = 0; } /* * Check if early retransmit can be attempted according to RFC 5827. * * If packet reordering is detected on a connection, fast recovery will * be delayed until it is clear that the packet was lost and not reordered. * But reordering detection is done only when SACK is enabled. * * On connections that do not support SACK, there is a limit on the number * of early retransmits that can be done per minute. This limit is needed * to make sure that too many packets are not retransmitted when there is * packet reordering. */ static void tcp_early_rexmt_check(struct tcpcb *tp, struct tcphdr *th) { u_int32_t obytes, snd_off; int32_t snd_len; struct socket *so = tp->t_inpcb->inp_socket; if ((SACK_ENABLED(tp) || tp->t_early_rexmt_count < TCP_EARLY_REXMT_LIMIT) && SEQ_GT(tp->snd_max, tp->snd_una) && (tp->t_dupacks == 1 || (SACK_ENABLED(tp) && !TAILQ_EMPTY(&tp->snd_holes)))) { /* * If there are only a few outstanding * segments on the connection, we might need * to lower the retransmit threshold. This * will allow us to do Early Retransmit as * described in RFC 5827. */ if (SACK_ENABLED(tp) && !TAILQ_EMPTY(&tp->snd_holes)) { obytes = (tp->snd_max - tp->snd_fack) + tp->sackhint.sack_bytes_rexmit; } else { obytes = (tp->snd_max - tp->snd_una); } /* * In order to lower retransmit threshold the * following two conditions must be met. * 1. the amount of outstanding data is less * than 4*SMSS bytes * 2. there is no unsent data ready for * transmission or the advertised window * will limit sending new segments. */ snd_off = tp->snd_max - tp->snd_una; snd_len = min(so->so_snd.sb_cc, tp->snd_wnd) - snd_off; if (obytes < (tp->t_maxseg << 2) && snd_len <= 0) { u_int32_t osegs; osegs = obytes / tp->t_maxseg; if ((osegs * tp->t_maxseg) < obytes) { osegs++; } /* * Since the connection might have already * received some dupacks, we add them to * to the outstanding segments count to get * the correct retransmit threshold. * * By checking for early retransmit after * receiving some duplicate acks when SACK * is supported, the connection will * enter fast recovery even if multiple * segments are lost in the same window. */ osegs += tp->t_dupacks; if (osegs < 4) { tp->t_rexmtthresh = ((osegs - 1) > 1) ? ((uint8_t)osegs - 1) : 1; tp->t_rexmtthresh = MIN(tp->t_rexmtthresh, tcprexmtthresh); tp->t_rexmtthresh = MAX(tp->t_rexmtthresh, tp->t_dupacks > UINT8_MAX ? UINT8_MAX : (uint8_t)tp->t_dupacks); if (tp->t_early_rexmt_count == 0) { tp->t_early_rexmt_win = tcp_now; } if (tp->t_flagsext & TF_SENT_TLPROBE) { tcpstat.tcps_tlp_recovery++; tcp_ccdbg_trace(tp, th, TCP_CC_TLP_RECOVERY); } else { tcpstat.tcps_early_rexmt++; tp->t_early_rexmt_count++; tcp_ccdbg_trace(tp, th, TCP_CC_EARLY_RETRANSMIT); } } } } /* * If we ever sent a TLP probe, the acknowledgement will trigger * early retransmit because the value of snd_fack will be close * to snd_max. This will take care of adjustments to the * congestion window. So we can reset TF_SENT_PROBE flag. */ tp->t_flagsext &= ~(TF_SENT_TLPROBE); tp->t_tlphighrxt = 0; tp->t_tlpstart = 0; } static boolean_t tcp_tfo_syn(struct tcpcb *tp, struct tcpopt *to) { u_char out[CCAES_BLOCK_SIZE]; unsigned char len; if (!(to->to_flags & (TOF_TFO | TOF_TFOREQ)) || !(tcp_fastopen & TCP_FASTOPEN_SERVER)) { return FALSE; } if ((to->to_flags & TOF_TFOREQ)) { tp->t_tfo_flags |= TFO_F_OFFER_COOKIE; tp->t_tfo_stats |= TFO_S_COOKIEREQ_RECV; tcpstat.tcps_tfo_cookie_req_rcv++; return FALSE; } /* Ok, then it must be an offered cookie. We need to check that ... */ tcp_tfo_gen_cookie(tp->t_inpcb, out, sizeof(out)); len = *to->to_tfo - TCPOLEN_FASTOPEN_REQ; to->to_tfo++; if (memcmp(out, to->to_tfo, len)) { /* Cookies are different! Let's return and offer a new cookie */ tp->t_tfo_flags |= TFO_F_OFFER_COOKIE; tp->t_tfo_stats |= TFO_S_COOKIE_INVALID; tcpstat.tcps_tfo_cookie_invalid++; return FALSE; } if (OSIncrementAtomic(&tcp_tfo_halfcnt) >= tcp_tfo_backlog) { /* Need to decrement again as we just increased it... */ OSDecrementAtomic(&tcp_tfo_halfcnt); return FALSE; } tp->t_tfo_flags |= TFO_F_COOKIE_VALID; tp->t_tfo_stats |= TFO_S_SYNDATA_RCV; tcpstat.tcps_tfo_syn_data_rcv++; return TRUE; } static void tcp_tfo_synack(struct tcpcb *tp, struct tcpopt *to) { if (to->to_flags & TOF_TFO) { unsigned char len = *to->to_tfo - TCPOLEN_FASTOPEN_REQ; /* * If this happens, things have gone terribly wrong. len should * have been checked in tcp_dooptions. */ VERIFY(len <= TFO_COOKIE_LEN_MAX); to->to_tfo++; tcp_cache_set_cookie(tp, to->to_tfo, len); tcp_heuristic_tfo_success(tp); tp->t_tfo_stats |= TFO_S_COOKIE_RCV; tcpstat.tcps_tfo_cookie_rcv++; if (tp->t_tfo_flags & TFO_F_COOKIE_SENT) { tcpstat.tcps_tfo_cookie_wrong++; tp->t_tfo_stats |= TFO_S_COOKIE_WRONG; } } else { /* * Thus, no cookie in the response, but we either asked for one * or sent SYN+DATA. Now, we need to check whether we had to * rexmit the SYN. If that's the case, it's better to start * backing of TFO-cookie requests. */ if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) && tp->t_tfo_flags & TFO_F_SYN_LOSS) { tp->t_tfo_stats |= TFO_S_SYN_LOSS; tcpstat.tcps_tfo_syn_loss++; tcp_heuristic_tfo_loss(tp); } else { if (tp->t_tfo_flags & TFO_F_COOKIE_REQ) { tp->t_tfo_stats |= TFO_S_NO_COOKIE_RCV; tcpstat.tcps_tfo_no_cookie_rcv++; } tcp_heuristic_tfo_success(tp); } } } static void tcp_tfo_rcv_probe(struct tcpcb *tp, int tlen) { if (tlen != 0) { return; } tp->t_tfo_probe_state = TFO_PROBE_PROBING; /* * We send the probe out rather quickly (after one RTO). It does not * really hurt that much, it's only one additional segment on the wire. */ tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, (TCP_REXMTVAL(tp))); } static void tcp_tfo_rcv_data(struct tcpcb *tp) { /* Transition from PROBING to NONE as data has been received */ if (tp->t_tfo_probe_state >= TFO_PROBE_PROBING) { tp->t_tfo_probe_state = TFO_PROBE_NONE; } } static void tcp_tfo_rcv_ack(struct tcpcb *tp, struct tcphdr *th) { if (tp->t_tfo_probe_state == TFO_PROBE_PROBING && tp->t_tfo_probes > 0) { if (th->th_seq == tp->rcv_nxt) { /* No hole, so stop probing */ tp->t_tfo_probe_state = TFO_PROBE_NONE; } else if (SEQ_GT(th->th_seq, tp->rcv_nxt)) { /* There is a hole! Wait a bit for data... */ tp->t_tfo_probe_state = TFO_PROBE_WAIT_DATA; tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_REXMTVAL(tp)); } } } /* * Update snd_wnd information. */ static inline bool tcp_update_window(struct tcpcb *tp, int thflags, struct tcphdr * th, u_int32_t tiwin, int tlen) { /* Don't look at the window if there is no ACK flag */ if ((thflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { /* keep track of pure window updates */ if (tlen == 0 && tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) { tcpstat.tcps_rcvwinupd++; } tp->snd_wnd = tiwin; tp->snd_wl1 = th->th_seq; tp->snd_wl2 = th->th_ack; if (tp->snd_wnd > tp->max_sndwnd) { tp->max_sndwnd = tp->snd_wnd; } if (tp->t_inpcb->inp_socket->so_flags & SOF_MP_SUBFLOW) { mptcp_update_window_wakeup(tp); } return true; } return false; } static void tcp_handle_wakeup(struct socket *so, int read_wakeup, int write_wakeup) { if (read_wakeup != 0) { sorwakeup(so); } if (write_wakeup != 0) { sowwakeup(so); } } static void tcp_update_snd_una(struct tcpcb *tp, uint32_t ack) { tp->snd_una = ack; if (SACK_ENABLED(tp) && SEQ_LT(tp->send_highest_sack, tp->snd_una)) { tp->send_highest_sack = tp->snd_una; /* If we move our marker, we need to start fresh */ tp->t_new_dupacks = 0; } } static bool tcp_syn_data_valid(struct tcpcb *tp, struct tcphdr *tcp_hdr, int tlen) { /* No data? */ if (tlen <= 0) { return false; } /* Not the right sequence-number? */ if (tcp_hdr->th_seq != tp->irs) { return false; } /* We could have wrapped around, check that */ if (tp->t_inpcb->inp_stat->rxbytes > INT32_MAX) { return false; } return true; } /* Process IP-ECN codepoints on received packets and update receive side counters */ static void tcp_input_ip_ecn(struct tcpcb *tp, struct inpcb *inp, uint32_t tlen, uint32_t segment_count, uint8_t ip_ecn) { switch (ip_ecn) { case IPTOS_ECN_ECT1: tp->ecn_flags |= TE_ACO_ECT1; tp->t_rcv_ect1_bytes += tlen; break; case IPTOS_ECN_ECT0: tp->ecn_flags |= TE_ACO_ECT0; tp->t_rcv_ect0_bytes += tlen; break; case IPTOS_ECN_CE: tp->t_rcv_ce_packets += segment_count; tp->t_rcv_ce_bytes += tlen; tp->t_ecn_recv_ce++; tcpstat.tcps_ecn_recv_ce++; INP_INC_IFNET_STAT(inp, ecn_recv_ce); break; default: /* No counter for Not-ECT */ break; } } /* Process SYN packet that wishes to negotiate Accurate ECN */ static void tcp_input_process_accecn_syn(struct tcpcb *tp, int ace_flags, uint8_t ip_ecn) { switch (ace_flags) { case (0 | 0 | 0): /* No ECN */ tp->t_server_accecn_state = tcp_connection_server_no_ecn_requested; break; case (0 | TH_CWR | TH_ECE): /* Legacy ECN-setup */ tp->ecn_flags |= (TE_SETUPRECEIVED | TE_SENDIPECT); tp->t_server_accecn_state = tcp_connection_server_classic_ecn_requested; break; case (TH_ACE): /* Accurate ECN */ if (TCP_ACC_ECN_ENABLED(tp)) { switch (ip_ecn) { case IPTOS_ECN_NOTECT: tp->ecn_flags |= TE_ACE_SETUP_NON_ECT; break; case IPTOS_ECN_ECT1: tp->ecn_flags |= TE_ACE_SETUP_ECT1; break; case IPTOS_ECN_ECT0: tp->ecn_flags |= TE_ACE_SETUP_ECT0; break; case IPTOS_ECN_CE: tp->ecn_flags |= TE_ACE_SETUP_CE; break; } /* * We are not yet committing to send IP ECT packets when * Accurate ECN is enabled */ tp->ecn_flags |= (TE_ACE_SETUPRECEIVED); /* Initialize ECT byte counter to 1 to distinguish zeroing of options */ tp->t_rcv_ect1_bytes = tp->t_rcv_ect0_bytes = 1; tp->t_snd_ect1_bytes = tp->t_snd_ect0_bytes = 1; tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_requested; } else { /* * If AccECN is not enabled, ignore * the TH_AE bit and do Legacy ECN-setup */ tp->ecn_flags |= (TE_SETUPRECEIVED | TE_SENDIPECT); } default: /* Forward Compatibility */ /* Accurate ECN */ if (TCP_ACC_ECN_ENABLED(tp)) { switch (ip_ecn) { case IPTOS_ECN_NOTECT: tp->ecn_flags |= TE_ACE_SETUP_NON_ECT; break; case IPTOS_ECN_ECT1: tp->ecn_flags |= TE_ACE_SETUP_ECT1; break; case IPTOS_ECN_ECT0: tp->ecn_flags |= TE_ACE_SETUP_ECT0; break; case IPTOS_ECN_CE: tp->ecn_flags |= TE_ACE_SETUP_CE; break; } /* * We are not yet committing to send IP ECT packets when * Accurate ECN is enabled */ tp->ecn_flags |= (TE_ACE_SETUPRECEIVED); /* Initialize ECT byte counter to 1 to distinguish zeroing of options */ tp->t_rcv_ect1_bytes = tp->t_rcv_ect0_bytes = 1; tp->t_snd_ect1_bytes = tp->t_snd_ect0_bytes = 1; tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_requested; } break; } } void tcp_input(struct mbuf *m, int off0) { int exiting_fr = 0; struct tcphdr *th; struct ip *ip = NULL; struct inpcb *inp; u_char *optp = NULL; int optlen = 0; int tlen, off; int drop_hdrlen; struct tcpcb *tp = 0; int thflags; struct socket *so = 0; int todrop, acked, ourfinisacked, needoutput = 0; int read_wakeup = 0; int write_wakeup = 0; struct in_addr laddr; struct in6_addr laddr6; int dropsocket = 0; int iss = 0, nosock = 0; u_int32_t tiwin, sack_bytes_acked = 0, sack_bytes_newly_acked = 0; struct tcpopt to; /* options in this segment */ #if TCPDEBUG short ostate = 0; #endif u_char ip_ecn = IPTOS_ECN_NOTECT; unsigned int ifscope; uint8_t isconnected, isdisconnected; struct ifnet *ifp = m->m_pkthdr.rcvif; int segment_count = m->m_pkthdr.seg_cnt ? : 1; int win; u_int16_t pf_tag = 0; #if MPTCP struct mptcb *mp_tp = NULL; #endif /* MPTCP */ boolean_t cell = IFNET_IS_CELLULAR(ifp); boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp)); boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp)); boolean_t recvd_dsack = FALSE; struct tcp_respond_args tra; int prev_t_state; boolean_t check_cfil = cfil_filter_present(); bool findpcb_iterated = false; /* * The mbuf may be freed after it has been added to the receive socket * buffer or the reassembly queue, so we reinitialize th to point to a * safe copy of the TCP header */ struct tcphdr saved_tcphdr = {}; /* * Save copy of the IPv4/IPv6 header. * Note: use array of uint32_t to silence compiler warning when casting * to a struct ip6_hdr pointer. */ #define MAX_IPWORDS ((sizeof(struct ip) + MAX_IPOPTLEN) / sizeof(uint32_t)) uint32_t saved_hdr[MAX_IPWORDS]; #define TCP_INC_VAR(stat, npkts) do { \ stat += npkts; \ } while (0) if (tcp_ack_strategy == TCP_ACK_STRATEGY_LEGACY) { segment_count = 1; } TCP_INC_VAR(tcpstat.tcps_rcvtotal, segment_count); struct ip6_hdr *ip6 = NULL; int isipv6; struct proc *kernel_proc = current_proc(); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_START, 0, 0, 0, 0, 0); isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; bzero((char *)&to, sizeof(to)); m_add_crumb(m, PKT_CRUMB_TCP_INPUT); if (m->m_flags & M_PKTHDR) { pf_tag = m_pftag(m)->pftag_tag; } if (isipv6) { /* * Expect 32-bit aligned data pointer on * strict-align platforms */ MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */ ip6 = mtod(m, struct ip6_hdr *); tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0); if (tcp_input_checksum(AF_INET6, m, th, off0, tlen)) { TCP_LOG_DROP_PKT(ip6, th, ifp, "IPv6 bad tcp checksum"); goto dropnosock; } KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport), (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])), th->th_seq, th->th_ack, th->th_win); /* * Be proactive about unspecified IPv6 address in source. * As we use all-zero to indicate unbounded/unconnected pcb, * unspecified IPv6 address can be used to confuse us. * * Note that packets with unspecified IPv6 destination is * already dropped in ip6_input. */ if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { /* XXX stat */ IF_TCP_STATINC(ifp, unspecv6); TCP_LOG_DROP_PKT(ip6, th, ifp, "src IPv6 address unspecified"); goto dropnosock; } DTRACE_TCP5(receive, struct mbuf *, m, struct inpcb *, NULL, struct ip6_hdr *, ip6, struct tcpcb *, NULL, struct tcphdr *, th); ip_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; } else { /* * Get IP and TCP header together in first mbuf. * Note: IP leaves IP header in first mbuf. */ if (off0 > sizeof(struct ip)) { ip_stripoptions(m); off0 = sizeof(struct ip); } if (m->m_len < sizeof(struct tcpiphdr)) { if ((m = m_pullup(m, sizeof(struct tcpiphdr))) == 0) { tcpstat.tcps_rcvshort++; return; } } /* Expect 32-bit aligned data pointer on strict-align platforms */ MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); ip = mtod(m, struct ip *); th = (struct tcphdr *)(void *)((caddr_t)ip + off0); tlen = ip->ip_len; if (tcp_input_checksum(AF_INET, m, th, off0, tlen)) { TCP_LOG_DROP_PKT(ip, th, ifp, "IPv4 bad tcp checksum"); goto dropnosock; } /* Re-initialization for later version check */ ip->ip_v = IPVERSION; ip_ecn = (ip->ip_tos & IPTOS_ECN_MASK); DTRACE_TCP5(receive, struct mbuf *, m, struct inpcb *, NULL, struct ip *, ip, struct tcpcb *, NULL, struct tcphdr *, th); KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport), (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), th->th_seq, th->th_ack, th->th_win); } #define TCP_LOG_HDR (isipv6 ? (void *)ip6 : (void *)ip) /* * Check that TCP offset makes sense, * pull out TCP options and adjust length. */ off = th->th_off << 2; if (off < sizeof(struct tcphdr) || off > tlen) { tcpstat.tcps_rcvbadoff++; IF_TCP_STATINC(ifp, badformat); TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "bad tcp offset"); goto dropnosock; } tlen -= off; /* tlen is used instead of ti->ti_len */ if (off > sizeof(struct tcphdr)) { if (isipv6) { IP6_EXTHDR_CHECK(m, off0, off, return ); ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0); } else { if (m->m_len < sizeof(struct ip) + off) { if ((m = m_pullup(m, sizeof(struct ip) + off)) == 0) { tcpstat.tcps_rcvshort++; return; } ip = mtod(m, struct ip *); th = (struct tcphdr *)(void *)((caddr_t)ip + off0); } } optlen = off - sizeof(struct tcphdr); optp = (u_char *)(th + 1); /* * Do quick retrieval of timestamp options ("options * prediction?"). If timestamp is the only option and it's * formatted as recommended in RFC 1323 appendix A, we * quickly get the values now and not bother calling * tcp_dooptions(), etc. */ if ((optlen == TCPOLEN_TSTAMP_APPA || (optlen > TCPOLEN_TSTAMP_APPA && optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && *(u_int32_t *)(void *)optp == htonl(TCPOPT_TSTAMP_HDR) && (th->th_flags & TH_SYN) == 0) { to.to_flags |= TOF_TS; to.to_tsval = ntohl(*(u_int32_t *)(void *)(optp + 4)); to.to_tsecr = ntohl(*(u_int32_t *)(void *)(optp + 8)); optp = NULL; /* we've parsed the options */ } } thflags = th->th_flags; /* * Drop all packets with both the SYN and FIN bits set. * This prevents e.g. nmap from identifying the TCP/IP stack. * * This is a violation of the TCP specification. */ if ((thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN)) { IF_TCP_STATINC(ifp, synfin); TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "drop SYN FIN"); goto dropnosock; } /* * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options, * until after ip6_savecontrol() is called and before other functions * which don't want those proto headers. * Because ip6_savecontrol() is going to parse the mbuf to * search for data to be passed up to user-land, it wants mbuf * parameters to be unchanged. */ drop_hdrlen = off0 + off; /* Since this is an entry point for input processing of tcp packets, we * can update the tcp clock here. */ calculate_tcp_clock(); /* * Record the interface where this segment arrived on; this does not * affect normal data output (for non-detached TCP) as it provides a * hint about which route and interface to use for sending in the * absence of a PCB, when scoped routing (and thus source interface * selection) are enabled. */ if ((m->m_pkthdr.pkt_flags & PKTF_LOOP) || m->m_pkthdr.rcvif == NULL) { ifscope = IFSCOPE_NONE; } else { ifscope = m->m_pkthdr.rcvif->if_index; } /* * Convert TCP protocol specific fields to host format. */ #if BYTE_ORDER != BIG_ENDIAN NTOHL(th->th_seq); NTOHL(th->th_ack); NTOHS(th->th_win); NTOHS(th->th_urp); #endif /* * Locate pcb for segment. */ findpcb: isconnected = FALSE; isdisconnected = FALSE; if (isipv6) { inp = in6_pcblookup_hash(&tcbinfo, &ip6->ip6_src, th->th_sport, ip6_input_getsrcifscope(m), &ip6->ip6_dst, th->th_dport, ip6_input_getdstifscope(m), 1, m->m_pkthdr.rcvif); } else { inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport, ip->ip_dst, th->th_dport, 1, m->m_pkthdr.rcvif); } /* * Use the interface scope information from the PCB for outbound * segments. If the PCB isn't present and if scoped routing is * enabled, tcp_respond will use the scope of the interface where * the segment arrived on. */ if (inp != NULL && (inp->inp_flags & INP_BOUND_IF)) { ifscope = inp->inp_boundifp->if_index; } /* * If the state is CLOSED (i.e., TCB does not exist) then * all data in the incoming segment is discarded. * If the TCB exists but is in CLOSED state, it is embryonic, * but should either do a listen or a connect soon. */ if (inp == NULL) { if (log_in_vain) { char dbuf[MAX_IPv6_STR_LEN], sbuf[MAX_IPv6_STR_LEN]; if (isipv6) { inet_ntop(AF_INET6, &ip6->ip6_dst, dbuf, sizeof(dbuf)); inet_ntop(AF_INET6, &ip6->ip6_src, sbuf, sizeof(sbuf)); } else { inet_ntop(AF_INET, &ip->ip_dst, dbuf, sizeof(dbuf)); inet_ntop(AF_INET, &ip->ip_src, sbuf, sizeof(sbuf)); } switch (log_in_vain) { case 1: if (thflags & TH_SYN) { log(LOG_INFO, "Connection attempt to TCP %s:%d from %s:%d\n", dbuf, ntohs(th->th_dport), sbuf, ntohs(th->th_sport)); } break; case 2: log(LOG_INFO, "Connection attempt to TCP %s:%d from %s:%d flags:0x%x\n", dbuf, ntohs(th->th_dport), sbuf, ntohs(th->th_sport), thflags); break; case 3: case 4: if ((thflags & TH_SYN) && !(thflags & TH_ACK) && !(m->m_flags & (M_BCAST | M_MCAST)) && ((isipv6 && !in6_are_addr_equal_scoped(&ip6->ip6_dst, &ip6->ip6_src, ip6_input_getdstifscope(m), ip6_input_getsrcifscope(m))) || (!isipv6 && ip->ip_dst.s_addr != ip->ip_src.s_addr))) { log_in_vain_log((LOG_INFO, "Stealth Mode connection attempt to TCP %s:%d from %s:%d\n", dbuf, ntohs(th->th_dport), sbuf, ntohs(th->th_sport))); } break; default: break; } } if (blackhole) { if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type != IFT_LOOP) { switch (blackhole) { case 1: if (thflags & TH_SYN) { TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "blackhole 1 syn for closed port"); goto dropnosock; } break; case 2: TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "blackhole 2 closed port"); goto dropnosock; default: TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "blackhole closed port"); goto dropnosock; } } } IF_TCP_STATINC(ifp, noconnnolist); TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "closed port"); goto dropwithresetnosock; } so = inp->inp_socket; if (so == NULL) { /* This case shouldn't happen as the socket shouldn't be null * if inp_state isn't set to INPCB_STATE_DEAD * But just in case, we pretend we didn't find the socket if we hit this case * as this isn't cause for a panic (the socket might be leaked however)... */ inp = NULL; #if TEMPDEBUG printf("tcp_input: no more socket for inp=%x. This shouldn't happen\n", inp); #endif TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "inp_socket NULL"); goto dropnosock; } socket_lock(so, 1); if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) { socket_unlock(so, 1); inp = NULL; // pretend we didn't find it TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "inp state WNT_STOPUSING"); goto dropnosock; } if (!isipv6 && inp->inp_faddr.s_addr != INADDR_ANY) { if (inp->inp_faddr.s_addr != ip->ip_src.s_addr || inp->inp_laddr.s_addr != ip->ip_dst.s_addr || inp->inp_fport != th->th_sport || inp->inp_lport != th->th_dport) { os_log_error(OS_LOG_DEFAULT, "%s 5-tuple does not match: %u:%u %u:%u\n", __func__, ntohs(inp->inp_fport), ntohs(th->th_sport), ntohs(inp->inp_lport), ntohs(th->th_dport)); if (findpcb_iterated) { goto drop; } findpcb_iterated = true; socket_unlock(so, 1); inp = NULL; goto findpcb; } } else if (isipv6 && !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) { if (!in6_are_addr_equal_scoped(&inp->in6p_faddr, &ip6->ip6_src, inp->inp_fifscope, ip6_input_getsrcifscope(m)) || !in6_are_addr_equal_scoped(&inp->in6p_laddr, &ip6->ip6_dst, inp->inp_lifscope, ip6_input_getdstifscope(m)) || inp->inp_fport != th->th_sport || inp->inp_lport != th->th_dport) { os_log_error(OS_LOG_DEFAULT, "%s 5-tuple does not match: %u:%u %u:%u\n", __func__, ntohs(inp->inp_fport), ntohs(th->th_sport), ntohs(inp->inp_lport), ntohs(th->th_dport)); if (findpcb_iterated) { goto drop; } findpcb_iterated = true; socket_unlock(so, 1); inp = NULL; goto findpcb; } } tp = intotcpcb(inp); if (tp == NULL) { IF_TCP_STATINC(ifp, noconnlist); TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "tp is NULL"); goto dropwithreset; } /* Now that we found the tcpcb, we can adjust the TCP timestamp */ if (to.to_flags & TOF_TS) { to.to_tsecr -= tp->t_ts_offset; } if (tp->t_state == TCPS_CLOSED) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "tp state TCPS_CLOSED"); goto drop; } #if NECP if (so->so_state & SS_ISCONNECTED) { // Connected TCP sockets have a fully-bound local and remote, // so the policy check doesn't need to override addresses if (!necp_socket_is_allowed_to_send_recv(inp, ifp, pf_tag, NULL, NULL, NULL, NULL)) { TCP_LOG_DROP_NECP(TCP_LOG_HDR, th, intotcpcb(inp), false); IF_TCP_STATINC(ifp, badformat); goto drop; } } else { /* * If the proc_uuid_policy table has been updated since the last use * of the listening socket (i.e., the proc_uuid_policy_table_gencount * has been updated), the flags in the socket may be out of date. * If INP2_WANT_APP_POLICY is stale, inbound packets may * be dropped by NECP if the socket should now match a per-app * exception policy. * In order to avoid this refresh the proc_uuid_policy state to * potentially recalculate the socket's flags before checking * with NECP. */ (void) inp_update_policy(inp); if (isipv6) { if (!necp_socket_is_allowed_to_send_recv_v6(inp, th->th_dport, th->th_sport, &ip6->ip6_dst, &ip6->ip6_src, ifp, pf_tag, NULL, NULL, NULL, NULL)) { TCP_LOG_DROP_NECP(TCP_LOG_HDR, th, intotcpcb(inp), false); IF_TCP_STATINC(ifp, badformat); goto drop; } } else { if (!necp_socket_is_allowed_to_send_recv_v4(inp, th->th_dport, th->th_sport, &ip->ip_dst, &ip->ip_src, ifp, pf_tag, NULL, NULL, NULL, NULL)) { TCP_LOG_DROP_NECP(TCP_LOG_HDR, th, intotcpcb(inp), false); IF_TCP_STATINC(ifp, badformat); goto drop; } } } #endif /* NECP */ prev_t_state = tp->t_state; /* If none of the FIN|SYN|RST|ACK flag is set, drop */ if ((thflags & TH_ACCEPT) == 0) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 TH_ACCEPT == 0"); goto drop; } /* Unscale the window into a 32-bit value. */ if ((thflags & TH_SYN) == 0) { tiwin = th->th_win << tp->snd_scale; } else { tiwin = th->th_win; } /* Avoid processing packets while closing a listen socket */ if (tp->t_state == TCPS_LISTEN && (so->so_options & SO_ACCEPTCONN) == 0) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "closing a listening socket"); goto drop; } if ((m->m_flags & M_PKTHDR) && (m->m_pkthdr.pkt_flags & PKTF_WAKE_PKT)) { soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_WAKE_PKT); } if (so->so_options & (SO_DEBUG | SO_ACCEPTCONN)) { #if TCPDEBUG if (so->so_options & SO_DEBUG) { ostate = tp->t_state; if (isipv6) { bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); } else { bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); } tcp_savetcp = *th; } #endif if (so->so_options & SO_ACCEPTCONN) { struct tcpcb *tp0 = tp; struct socket *so2; struct socket *oso; struct sockaddr_storage from; struct sockaddr_storage to2; struct inpcb *oinp = sotoinpcb(so); struct ifnet *head_ifscope; bool head_nocell, head_recvanyif, head_noexpensive, head_awdl_unrestricted, head_intcoproc_allowed, head_external_port, head_noconstrained, head_management_allowed; /* Get listener's bound-to-interface, if any */ head_ifscope = (inp->inp_flags & INP_BOUND_IF) ? inp->inp_boundifp : NULL; /* Get listener's no-cellular information, if any */ head_nocell = INP_NO_CELLULAR(inp); /* Get listener's recv-any-interface, if any */ head_recvanyif = (inp->inp_flags & INP_RECV_ANYIF); /* Get listener's no-expensive information, if any */ head_noexpensive = INP_NO_EXPENSIVE(inp); head_noconstrained = INP_NO_CONSTRAINED(inp); head_awdl_unrestricted = INP_AWDL_UNRESTRICTED(inp); head_intcoproc_allowed = INP_INTCOPROC_ALLOWED(inp); head_external_port = (inp->inp_flags2 & INP2_EXTERNAL_PORT); head_management_allowed = INP_MANAGEMENT_ALLOWED(inp); /* * If the state is LISTEN then ignore segment if it contains an RST. * If the segment contains an ACK then it is bad and send a RST. * If it does not contain a SYN then it is not interesting; drop it. * If it is from this socket, drop it, it must be forged. */ if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) { IF_TCP_STATINC(ifp, listbadsyn); if (thflags & TH_RST) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, thflags & TH_SYN ? "ignore SYN with RST" : "ignore RST"); goto drop; } if (thflags & TH_ACK) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, thflags & TH_SYN ? "bad SYN with ACK" : "bad ACK"); tp = NULL; tcpstat.tcps_badsyn++; goto dropwithreset; } /* We come here if there is no SYN set */ tcpstat.tcps_badsyn++; TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad SYN"); goto drop; } KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_START, 0, 0, 0, 0, 0); if (th->th_dport == th->th_sport) { if (isipv6) { if (in6_are_addr_equal_scoped(&ip6->ip6_dst, &ip6->ip6_src, ip6_input_getdstifscope(m), ip6_input_getsrcifscope(m))) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad tuple same port"); goto drop; } } else if (ip->ip_dst.s_addr == ip->ip_src.s_addr) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad tuple same IPv4 address"); goto drop; } } /* * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN * in_broadcast() should never return true on a received * packet with M_BCAST not set. * * Packets with a multicast source address should also * be discarded. */ if (m->m_flags & (M_BCAST | M_MCAST)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "mbuf M_BCAST | M_MCAST"); goto drop; } if (isipv6) { if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "IN6_IS_ADDR_MULTICAST"); goto drop; } } else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "multicast or broadcast address"); goto drop; } /* * If deprecated address is forbidden, * we do not accept SYN to deprecated interface * address to prevent any new inbound connection from * getting established. * When we do not accept SYN, we send a TCP RST, * with deprecated source address (instead of dropping * it). We compromise it as it is much better for peer * to send a RST, and RST will be the final packet * for the exchange. * * If we do not forbid deprecated addresses, we accept * the SYN packet. RFC 4862 forbids dropping SYN in * this case. */ if (isipv6 && !ip6_use_deprecated) { uint32_t ia6_flags; if (ip6_getdstifaddr_info(m, NULL, &ia6_flags) == 0) { if (ia6_flags & IN6_IFF_DEPRECATED) { tp = NULL; IF_TCP_STATINC(ifp, deprecate6); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "deprecated IPv6 address"); goto dropwithreset; } } } if (so->so_filt || check_cfil) { if (isipv6) { struct sockaddr_in6 *sin6 = SIN6(&from); sin6->sin6_len = sizeof(*sin6); sin6->sin6_family = AF_INET6; sin6->sin6_port = th->th_sport; sin6->sin6_flowinfo = 0; sin6->sin6_addr = ip6->ip6_src; sin6->sin6_scope_id = 0; sin6 = SIN6(&to2); sin6->sin6_len = sizeof(struct sockaddr_in6); sin6->sin6_family = AF_INET6; sin6->sin6_port = th->th_dport; sin6->sin6_flowinfo = 0; sin6->sin6_addr = ip6->ip6_dst; sin6->sin6_scope_id = 0; } else { struct sockaddr_in *sin = SIN(&from); sin->sin_len = sizeof(*sin); sin->sin_family = AF_INET; sin->sin_port = th->th_sport; sin->sin_addr = ip->ip_src; sin = SIN(&to2); sin->sin_len = sizeof(struct sockaddr_in); sin->sin_family = AF_INET; sin->sin_port = th->th_dport; sin->sin_addr = ip->ip_dst; } } if (so->so_filt) { so2 = sonewconn(so, 0, SA(&from)); } else { so2 = sonewconn(so, 0, NULL); } if (so2 == 0) { tcpstat.tcps_listendrop++; if (tcp_dropdropablreq(so)) { if (so->so_filt) { so2 = sonewconn(so, 0, SA(&from)); } else { so2 = sonewconn(so, 0, NULL); } } if (!so2) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " listen drop"); goto drop; } } /* Point "inp" and "tp" in tandem to new socket */ inp = (struct inpcb *)so2->so_pcb; tp = intotcpcb(inp); oso = so; socket_unlock(so, 0); /* Unlock but keep a reference on listener for now */ so = so2; socket_lock(so, 1); /* * Mark socket as temporary until we're * committed to keeping it. The code at * ``drop'' and ``dropwithreset'' check the * flag dropsocket to see if the temporary * socket created here should be discarded. * We mark the socket as discardable until * we're committed to it below in TCPS_LISTEN. * There are some error conditions in which we * have to drop the temporary socket. */ dropsocket++; /* * Inherit INP_BOUND_IF from listener; testing if * head_ifscope is non-NULL is sufficient, since it * can only be set to a non-zero value earlier if * the listener has such a flag set. */ if (head_ifscope != NULL) { inp->inp_flags |= INP_BOUND_IF; inp->inp_boundifp = head_ifscope; } else { inp->inp_flags &= ~INP_BOUND_IF; } /* * Inherit restrictions from listener. */ if (head_nocell) { inp_set_nocellular(inp); } if (head_noexpensive) { inp_set_noexpensive(inp); } if (head_noconstrained) { inp_set_noconstrained(inp); } if (head_awdl_unrestricted) { inp_set_awdl_unrestricted(inp); } if (head_intcoproc_allowed) { inp_set_intcoproc_allowed(inp); } if (head_management_allowed) { inp_set_management_allowed(inp); } /* * Inherit {IN,IN6}_RECV_ANYIF from listener. */ if (head_recvanyif) { inp->inp_flags |= INP_RECV_ANYIF; } else { inp->inp_flags &= ~INP_RECV_ANYIF; } if (head_external_port) { inp->inp_flags2 |= INP2_EXTERNAL_PORT; } if (isipv6) { inp->in6p_laddr = ip6->ip6_dst; inp->inp_lifscope = in6_addr2scopeid(ifp, &inp->in6p_laddr); in6_verify_ifscope(&ip6->ip6_dst, inp->inp_lifscope); } else { inp->inp_vflag &= ~INP_IPV6; inp->inp_vflag |= INP_IPV4; inp->inp_laddr = ip->ip_dst; } inp->inp_lport = th->th_dport; if (in_pcbinshash(inp, 0) != 0) { /* * Undo the assignments above if we failed to * put the PCB on the hash lists. */ if (isipv6) { inp->in6p_laddr = in6addr_any; inp->inp_lifscope = IFSCOPE_NONE; } else { inp->inp_laddr.s_addr = INADDR_ANY; } #if SKYWALK netns_release(&inp->inp_netns_token); #endif /* SKYWALK */ inp->inp_lport = 0; socket_lock(oso, 0); /* release ref on parent */ socket_unlock(oso, 1); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " in_pcbinshash failed"); goto drop; } socket_lock(oso, 0); if (isipv6) { /* * Inherit socket options from the listening * socket. * Note that in6p_inputopts are not (even * should not be) copied, since it stores * previously received options and is used to * detect if each new option is different than * the previous one and hence should be passed * to a user. * If we copied in6p_inputopts, a user would * not be able to receive options just after * calling the accept system call. */ inp->inp_flags |= oinp->inp_flags & INP_CONTROLOPTS; if (oinp->in6p_outputopts) { inp->in6p_outputopts = ip6_copypktopts(oinp->in6p_outputopts, Z_NOWAIT); } } else { inp->inp_options = ip_srcroute(); inp->inp_ip_tos = oinp->inp_ip_tos; } #if IPSEC /* copy old policy into new socket's */ if (sotoinpcb(oso)->inp_sp) { int error = 0; /* Is it a security hole here to silently fail to copy the policy? */ if (inp->inp_sp == NULL) { error = ipsec_init_policy(so, &inp->inp_sp); } if (error != 0 || ipsec_copy_policy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) { printf("tcp_input: could not copy policy\n"); } } #endif /* inherit states from the listener */ DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_LISTEN); TCP_LOG_STATE(tp, TCPS_LISTEN); tp->t_state = TCPS_LISTEN; tp->t_flags |= tp0->t_flags & (TF_NOPUSH | TF_NOOPT | TF_NODELAY); tp->t_flagsext |= (tp0->t_flagsext & (TF_RXTFINDROP | TF_NOTIMEWAIT | TF_FASTOPEN)); tp->t_keepinit = tp0->t_keepinit; tp->t_keepcnt = tp0->t_keepcnt; tp->t_keepintvl = tp0->t_keepintvl; tp->t_adaptive_wtimo = tp0->t_adaptive_wtimo; tp->t_adaptive_rtimo = tp0->t_adaptive_rtimo; tp->t_inpcb->inp_ip_ttl = tp0->t_inpcb->inp_ip_ttl; if ((so->so_flags & SOF_NOTSENT_LOWAT) != 0) { tp->t_notsent_lowat = tp0->t_notsent_lowat; } tp->t_inpcb->inp_flags2 |= tp0->t_inpcb->inp_flags2 & INP2_KEEPALIVE_OFFLOAD; /* now drop the reference on the listener */ socket_unlock(oso, 1); tcp_set_max_rwinscale(tp, so); #if CONTENT_FILTER if (check_cfil) { int error = cfil_sock_attach(so2, SA(&to2), SA(&from), CFS_CONNECTION_DIR_IN); if (error != 0) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " cfil_sock_attach failed"); goto drop; } } #endif /* CONTENT_FILTER */ KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_END, 0, 0, 0, 0, 0); } } socket_lock_assert_owned(so); /* * Packet accounting should not be done on listening socket */ if (th->th_flags & TH_SYN) { (void) os_add_overflow(1, tp->t_syn_rcvd, &tp->t_syn_rcvd); } if (th->th_flags & TH_FIN) { (void) os_add_overflow(1, tp->t_fin_rcvd, &tp->t_fin_rcvd); } if (th->th_flags & TH_RST) { (void) os_add_overflow(1, tp->t_rst_rcvd, &tp->t_rst_rcvd); } TCP_LOG_TH_FLAGS(TCP_LOG_HDR, th, tp, false, ifp); if (net_mpklog_enabled && (m->m_pkthdr.rcvif->if_xflags & IFXF_MPK_LOG)) { MPKL_TCP_INPUT(tcp_mpkl_log_object, ntohs(tp->t_inpcb->inp_lport), ntohs(tp->t_inpcb->inp_fport), th->th_seq, th->th_ack, tlen, thflags, so->last_pid, so->so_log_seqn++); } if (tp->t_state == TCPS_ESTABLISHED && tlen > 0) { /* * Evaluate the rate of arrival of packets to see if the * receiver can reduce the ack traffic. The algorithm to * stretch acks will be enabled if the connection meets * certain criteria defined in tcp_stretch_ack_enable function. */ if ((tp->t_flagsext & TF_RCVUNACK_WAITSS) != 0) { TCP_INC_VAR(tp->rcv_waitforss, segment_count); } if (tcp_stretch_ack_enable(tp, thflags)) { tp->t_flags |= TF_STRETCHACK; tp->t_flagsext &= ~(TF_RCVUNACK_WAITSS); tp->rcv_waitforss = 0; } else { tp->t_flags &= ~(TF_STRETCHACK); } if (TSTMP_GT(tp->rcv_unackwin - (tcp_rcvunackwin >> 1), tcp_now)) { tp->rcv_by_unackhalfwin += (tlen + off); tp->rcv_by_unackwin += (tlen + off); } else { tp->rcv_unackwin = tcp_now + tcp_rcvunackwin; tp->rcv_by_unackwin = tp->rcv_by_unackhalfwin + tlen + off; tp->rcv_by_unackhalfwin = tlen + off; } } if (tp->t_state == TCPS_ESTABLISHED && BYTES_ACKED(th, tp) > 0) { if (tp->ecn_flags & TE_SENDIPECT) { /* * Data sent with ECT has been acknowledged, calculate * packets approx. by dividing by MSS. This is done to * count MSS sized packets in case packets are aggregated * by GRO/LRO. */ uint32_t bytes_acked = tcp_round_to(BYTES_ACKED(th, tp), tp->t_maxseg); tp->t_ecn_capable_packets_acked += max(1, (bytes_acked / tp->t_maxseg)); } } /* Accurate ECN has different semantics for TH_CWR. */ if (!TCP_ACC_ECN_ENABLED(tp)) { /* * Clear TE_SENDECE if TH_CWR is set. This is harmless, so we don't * bother doing extensive checks for state and whatnot. */ if (thflags & TH_CWR) { tp->ecn_flags &= ~TE_SENDECE; tp->t_ecn_recv_cwr++; } } /* * Accurate ECN feedback * 1. Process peer's feedback in received TCP thflags and update s.cep * 2. Process IP ECN bits and update r.cep for CE marked pure ACKs * or valid data packets * */ if (TCP_ACC_ECN_ON(tp) && tp->t_state == TCPS_ESTABLISHED) { /* * Update s.cep if bytes have been acknowledged * otherwise, this ACK has already been superseded. */ uint8_t ace = tcp_get_ace(th); if (BYTES_ACKED(th, tp) > 0) { /* Congestion was experienced if delta_cep > 0 */ tp->t_delta_ce_packets = (ace + TCP_ACE_DIV - (tp->t_snd_ce_packets % TCP_ACE_DIV)) % TCP_ACE_DIV; tp->t_snd_ce_packets += tp->t_delta_ce_packets; } /* Update receive side counters */ if (tlen == 0 || (tlen > 0 && SEQ_GEQ(th->th_seq, tp->last_ack_sent) && SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd))) { tcp_input_ip_ecn(tp, inp, (uint32_t)tlen, (uint32_t)segment_count, ip_ecn); } /* Test for ACE bleaching, initial value of ace should be non-zero */ if (th->th_seq == tp->iss + 1 && ace == 0) { tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_ace_bleaching_detected; } } else { /* * Explicit Congestion Notification - Flag that we need to send ECE if * + The IP Congestion experienced flag was set. * + Socket is in established state * + We negotiated ECN in the TCP setup * + This isn't a pure ack (tlen > 0) * + The data is in the valid window * * TE_SENDECE will be cleared when we receive a packet with TH_CWR set. */ if (ip_ecn == IPTOS_ECN_CE && tp->t_state == TCPS_ESTABLISHED && TCP_ECN_ENABLED(tp) && tlen > 0 && SEQ_GEQ(th->th_seq, tp->last_ack_sent) && SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { tp->t_ecn_recv_ce++; tcpstat.tcps_ecn_recv_ce++; INP_INC_IFNET_STAT(inp, ecn_recv_ce); /* Mark this connection as it received CE from network */ tp->ecn_flags |= TE_RECV_ECN_CE; tp->ecn_flags |= TE_SENDECE; } } /* * If we received an explicit notification of congestion in * ip tos ecn bits or by the CWR bit in TCP header flags, reset * the ack-stretching state. We need to handle ECN notification if * an ECN setup SYN was sent even once. */ if (tp->t_state == TCPS_ESTABLISHED && (tp->ecn_flags & TE_SETUPSENT) && (ip_ecn == IPTOS_ECN_CE || (thflags & TH_CWR))) { tcp_reset_stretch_ack(tp); tp->t_forced_acks = TCP_FORCED_ACKS_COUNT; CLEAR_IAJ_STATE(tp); } if (ip_ecn == IPTOS_ECN_CE && tp->t_state == TCPS_ESTABLISHED && !TCP_ECN_ENABLED(tp) && !(tp->ecn_flags & TE_CEHEURI_SET)) { tcpstat.tcps_ecn_fallback_ce++; tcp_heuristic_ecn_aggressive(tp); tp->ecn_flags |= TE_CEHEURI_SET; } if (tp->t_state == TCPS_ESTABLISHED && TCP_ECN_ENABLED(tp) && ip_ecn == IPTOS_ECN_CE && !(tp->ecn_flags & TE_CEHEURI_SET)) { if (inp->inp_stat->rxpackets < ECN_MIN_CE_PROBES) { tp->t_ecn_recv_ce_pkt++; } else if (tp->t_ecn_recv_ce_pkt > ECN_MAX_CE_RATIO) { tcpstat.tcps_ecn_fallback_ce++; tcp_heuristic_ecn_aggressive(tp); tp->ecn_flags |= TE_CEHEURI_SET; INP_INC_IFNET_STAT(inp, ecn_fallback_ce); } else { /* We tracked the first ECN_MIN_CE_PROBES segments, we * now know that the path is good. */ tp->ecn_flags |= TE_CEHEURI_SET; } } /* Update rcvtime as a new segment was received on the connection */ tp->t_rcvtime = tcp_now; /* * Segment received on connection. * Reset idle time and keep-alive timer. */ if (TCPS_HAVEESTABLISHED(tp->t_state)) { tcp_keepalive_reset(tp); if (tp->t_mpsub) { mptcp_reset_keepalive(tp); } } /* * Process options if not in LISTEN state, * else do it below (after getting remote address). */ if (tp->t_state != TCPS_LISTEN && optp) { tcp_dooptions(tp, optp, optlen, th, &to); } #if MPTCP if (tp->t_state != TCPS_LISTEN && (so->so_flags & SOF_MP_SUBFLOW)) { mptcp_insert_rmap(tp, m, th); } #endif /* MPTCP */ if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { if (!(thflags & TH_ACK) || (SEQ_GT(th->th_ack, tp->iss) && SEQ_LEQ(th->th_ack, tp->snd_max))) { tcp_finalize_options(tp, &to, ifscope); } } #if TRAFFIC_MGT /* * Compute inter-packet arrival jitter. According to RFC 3550, * inter-packet arrival jitter is defined as the difference in * packet spacing at the receiver compared to the sender for a * pair of packets. When two packets of maximum segment size come * one after the other with consecutive sequence numbers, we * consider them as packets sent together at the sender and use * them as a pair to compute inter-packet arrival jitter. This * metric indicates the delay induced by the network components due * to queuing in edge/access routers. */ if (tp->t_state == TCPS_ESTABLISHED && (thflags & (TH_SYN | TH_FIN | TH_RST | TH_URG | TH_ACK | TH_ECE | TH_PUSH)) == TH_ACK && ((tp->t_flags & TF_NEEDFIN) == 0) && ((to.to_flags & TOF_TS) == 0 || TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && th->th_seq == tp->rcv_nxt && LIST_EMPTY(&tp->t_segq)) { int seg_size = tlen; if (tp->iaj_pktcnt <= IAJ_IGNORE_PKTCNT) { TCP_INC_VAR(tp->iaj_pktcnt, segment_count); } if (tp->iaj_size == 0 || seg_size > tp->iaj_size || (seg_size == tp->iaj_size && tp->iaj_rcv_ts == 0)) { /* * State related to inter-arrival jitter is * uninitialized or we are trying to find a good * first packet to start computing the metric */ update_iaj_state(tp, seg_size, 0); } else { if (seg_size == tp->iaj_size) { /* * Compute inter-arrival jitter taking * this packet as the second packet */ compute_iaj(tp); } if (seg_size < tp->iaj_size) { /* * There is a smaller packet in the stream. * Some times the maximum size supported * on a path can change if there is a new * link with smaller MTU. The receiver will * not know about this change. If there * are too many packets smaller than * iaj_size, we try to learn the iaj_size * again. */ TCP_INC_VAR(tp->iaj_small_pkt, segment_count); if (tp->iaj_small_pkt > RESET_IAJ_SIZE_THRESH) { update_iaj_state(tp, seg_size, 1); } else { CLEAR_IAJ_STATE(tp); } } else { update_iaj_state(tp, seg_size, 0); } } } else { CLEAR_IAJ_STATE(tp); } #endif /* TRAFFIC_MGT */ /* * Header prediction: check for the two common cases * of a uni-directional data xfer. If the packet has * no control flags, is in-sequence, the window didn't * change and we're not retransmitting, it's a * candidate. If the length is zero and the ack moved * forward, we're the sender side of the xfer. Just * free the data acked & wake any higher level process * that was blocked waiting for space. If the length * is non-zero and the ack didn't move, we're the * receiver side. If we're getting packets in-order * (the reassembly queue is empty), add the data to * the socket buffer and note that we need a delayed ack. * Make sure that the hidden state-flags are also off. * Since we check for TCPS_ESTABLISHED above, it can only * be TH_NEEDSYN. */ if (tp->t_state == TCPS_ESTABLISHED && !(so->so_state & SS_CANTRCVMORE) && (thflags & TH_FLAGS) == TH_ACK && ((tp->t_flags & TF_NEEDFIN) == 0) && ((to.to_flags & TOF_TS) == 0 || TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && th->th_seq == tp->rcv_nxt && tiwin && tiwin == tp->snd_wnd && tp->snd_nxt == tp->snd_max) { /* * If last ACK falls within this segment's sequence numbers, * record the timestamp. * NOTE that the test is modified according to the latest * proposal of the tcplw@cray.com list (Braden 1993/04/26). */ if ((to.to_flags & TOF_TS) != 0 && SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { tp->ts_recent_age = tcp_now; tp->ts_recent = to.to_tsval; } /* * We increment t_unacksegs_ce for both data segments * and pure ACKs for Accurate ECN */ if (TCP_ACC_ECN_ON(tp) && ip_ecn == IPTOS_ECN_CE) { TCP_INC_VAR(tp->t_unacksegs_ce, segment_count); } if (tlen == 0) { if (SEQ_GT(th->th_ack, tp->snd_una) && SEQ_LEQ(th->th_ack, tp->snd_max) && tp->snd_cwnd >= tp->snd_ssthresh && (!IN_FASTRECOVERY(tp) && ((!(SACK_ENABLED(tp)) && tp->t_dupacks < tp->t_rexmtthresh) || (SACK_ENABLED(tp) && to.to_nsacks == 0 && TAILQ_EMPTY(&tp->snd_holes))))) { /* * this is a pure ack for outstanding data. */ ++tcpstat.tcps_predack; tcp_bad_rexmt_check(tp, th, &to); /* Recalculate the RTT */ tcp_compute_rtt(tp, &to, th); VERIFY(SEQ_GEQ(th->th_ack, tp->snd_una)); acked = BYTES_ACKED(th, tp); tcpstat.tcps_rcvackpack++; tcpstat.tcps_rcvackbyte += acked; /* * Handle an ack that is in sequence during * congestion avoidance phase. The * calculations in this function * assume that snd_una is not updated yet. */ if (CC_ALGO(tp)->congestion_avd != NULL) { CC_ALGO(tp)->congestion_avd(tp, th); } tcp_ccdbg_trace(tp, th, TCP_CC_INSEQ_ACK_RCVD); sbdrop(&so->so_snd, acked); tcp_sbsnd_trim(&so->so_snd); if (SEQ_GT(tp->snd_una, tp->snd_recover) && SEQ_LEQ(th->th_ack, tp->snd_recover)) { tp->snd_recover = th->th_ack - 1; } tcp_update_snd_una(tp, th->th_ack); TCP_RESET_REXMT_STATE(tp); /* * pull snd_wl2 up to prevent seq wrap relative * to th_ack. */ tp->snd_wl2 = th->th_ack; if (tp->t_dupacks > 0) { tp->t_dupacks = 0; tp->t_rexmtthresh = tcprexmtthresh; tp->t_new_dupacks = 0; } tp->sackhint.sack_bytes_acked = 0; /* * If all outstanding data are acked, stop * retransmit timer, otherwise restart timer * using current (possibly backed-off) value. * If process is waiting for space, * wakeup/selwakeup/signal. If data * are ready to send, let tcp_output * decide between more output or persist. */ if (tp->snd_una == tp->snd_max) { tp->t_timer[TCPT_REXMT] = 0; tp->t_timer[TCPT_PTO] = 0; } else if (tp->t_timer[TCPT_PERSIST] == 0) { tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur); } if (!SLIST_EMPTY(&tp->t_rxt_segments) && !TCP_DSACK_SEQ_IN_WINDOW(tp, tp->t_dsack_lastuna, tp->snd_una)) { tcp_rxtseg_clean(tp); } if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 && tp->t_bwmeas != NULL) { tcp_bwmeas_check(tp); } write_wakeup = 1; if (!SLIST_EMPTY(&tp->t_notify_ack)) { tcp_notify_acknowledgement(tp, so); } if ((so->so_snd.sb_cc) || (tp->t_flags & TF_ACKNOW)) { (void) tcp_output(tp); } tcp_tfo_rcv_ack(tp, th); m_freem(m); tcp_check_timer_state(tp); tcp_handle_wakeup(so, read_wakeup, write_wakeup); socket_unlock(so, 1); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); return; } } else if (th->th_ack == tp->snd_una && LIST_EMPTY(&tp->t_segq) && tlen <= tcp_sbspace(tp)) { /* * this is a pure, in-sequence data packet * with nothing on the reassembly queue and * we have enough buffer space to take it. */ /* Clean receiver SACK report if present */ if (SACK_ENABLED(tp) && tp->rcv_numsacks) { tcp_clean_sackreport(tp); } ++tcpstat.tcps_preddat; tp->rcv_nxt += tlen; /* Update highest received sequence and its timestamp */ if (SEQ_LT(tp->rcv_high, tp->rcv_nxt)) { tp->rcv_high = tp->rcv_nxt; if (to.to_flags & TOF_TS) { tp->tsv_high = to.to_tsval; } } /* * Pull snd_wl1 up to prevent seq wrap relative to * th_seq. */ tp->snd_wl1 = th->th_seq; /* * Pull rcv_up up to prevent seq wrap relative to * rcv_nxt. */ tp->rcv_up = tp->rcv_nxt; TCP_INC_VAR(tcpstat.tcps_rcvpack, segment_count); tcpstat.tcps_rcvbyte += tlen; if (nstat_collect) { INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, tlen); inp_set_activity_bitmap(inp); } /* Calculate the RTT on the receiver */ tcp_compute_rcv_rtt(tp, &to, th); tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen); if (TCP_USE_RLEDBAT(tp, so) && tcp_cc_rledbat.data_rcvd != NULL) { tcp_cc_rledbat.data_rcvd(tp, th, &to, tlen); } /* * Add data to socket buffer. */ so_recv_data_stat(so, m, 0); m_adj(m, drop_hdrlen); /* delayed header drop */ if (isipv6) { memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); ip6 = (struct ip6_hdr *)&saved_hdr[0]; } else { memcpy(&saved_hdr, ip, ip->ip_hl << 2); ip = (struct ip *)&saved_hdr[0]; } memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); if (th->th_flags & TH_PUSH) { tp->t_flagsext |= TF_LAST_IS_PSH; } else { tp->t_flagsext &= ~TF_LAST_IS_PSH; } if (sbappendstream_rcvdemux(so, m)) { mptcp_handle_input(so); read_wakeup = 1; } th = &saved_tcphdr; if (isipv6) { KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])), th->th_seq, th->th_ack, th->th_win); } else { KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), th->th_seq, th->th_ack, th->th_win); } TCP_INC_VAR(tp->t_unacksegs, segment_count); if (DELAY_ACK(tp, th)) { if ((tp->t_flags & TF_DELACK) == 0) { tp->t_flags |= TF_DELACK; tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack); } } else { tp->t_flags |= TF_ACKNOW; tcp_output(tp); } tcp_adaptive_rwtimo_check(tp, tlen); if (tlen > 0) { tcp_tfo_rcv_data(tp); } tcp_check_timer_state(tp); tcp_handle_wakeup(so, read_wakeup, write_wakeup); socket_unlock(so, 1); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); return; } } /* * Calculate amount of space in receive window, * and then do TCP input processing. * Receive window is amount of space in rcv queue, * but not less than advertised window. */ socket_lock_assert_owned(so); win = tcp_sbspace(tp); if (win < 0) { win = 0; } else { /* clip rcv window to 4K for modems */ if (tp->t_flags & TF_SLOWLINK && slowlink_wsize > 0) { win = min(win, slowlink_wsize); } } tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); #if MPTCP /* * Ensure that the subflow receive window isn't greater * than the connection level receive window. */ if ((tp->t_mpflags & TMPF_MPTCP_TRUE) && (mp_tp = tptomptp(tp))) { socket_lock_assert_owned(mptetoso(mp_tp->mpt_mpte)); int64_t recwin_conn = (int64_t)(mp_tp->mpt_rcvadv - mp_tp->mpt_rcvnxt); VERIFY(recwin_conn < INT32_MAX && recwin_conn > INT32_MIN); if (recwin_conn > 0 && tp->rcv_wnd > (uint32_t)recwin_conn) { tp->rcv_wnd = (uint32_t)recwin_conn; tcpstat.tcps_mp_reducedwin++; } } #endif /* MPTCP */ switch (tp->t_state) { /* * Initialize tp->rcv_nxt, and tp->irs, select an initial * tp->iss, and send a segment: * * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. * Fill in remote peer address fields if not previously specified. * Enter SYN_RECEIVED state, and process any other fields of this * segment in this state. */ case TCPS_LISTEN: { struct sockaddr_in *sin; struct sockaddr_in6 *sin6; socket_lock_assert_owned(so); /* Clear the logging flags inherited from the listening socket */ inp->inp_log_flags = 0; inp->inp_flags2 |= INP2_LOGGED_SUMMARY; if (isipv6) { sin6 = kalloc_type(struct sockaddr_in6, Z_NOWAIT | Z_ZERO); if (sin6 == NULL) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "LISTEN kalloc_type failed"); goto drop; } sin6->sin6_family = AF_INET6; sin6->sin6_len = sizeof(*sin6); sin6->sin6_addr = ip6->ip6_src; sin6->sin6_port = th->th_sport; if (!in6_embedded_scope && IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { sin6->sin6_scope_id = ip6_input_getsrcifscope(m); } laddr6 = inp->in6p_laddr; uint32_t lifscope = inp->inp_lifscope; if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) { inp->in6p_laddr = ip6->ip6_dst; inp->inp_lifscope = in6_addr2scopeid(ifp, &inp->in6p_laddr); in6_verify_ifscope(&inp->in6p_laddr, inp->inp_lifscope); } if (in6_pcbconnect(inp, SA(sin6), kernel_proc)) { inp->in6p_laddr = laddr6; kfree_type(struct sockaddr_in6, sin6); inp->inp_lifscope = lifscope; in6_verify_ifscope(&inp->in6p_laddr, inp->inp_lifscope); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " LISTEN in6_pcbconnect failed"); goto drop; } kfree_type(struct sockaddr_in6, sin6); } else { socket_lock_assert_owned(so); sin = kalloc_type(struct sockaddr_in, Z_NOWAIT); if (sin == NULL) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "LISTEN kalloc_type failed"); goto drop; } sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = ip->ip_src; sin->sin_port = th->th_sport; bzero((caddr_t)sin->sin_zero, sizeof(sin->sin_zero)); laddr = inp->inp_laddr; if (inp->inp_laddr.s_addr == INADDR_ANY) { inp->inp_laddr = ip->ip_dst; } if (in_pcbconnect(inp, SA(sin), kernel_proc, IFSCOPE_NONE, NULL)) { inp->inp_laddr = laddr; kfree_type(struct sockaddr_in, sin); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " LISTEN in_pcbconnect failed"); goto drop; } kfree_type(struct sockaddr_in, sin); } tcp_dooptions(tp, optp, optlen, th, &to); tcp_finalize_options(tp, &to, ifscope); if (tfo_enabled(tp) && tcp_tfo_syn(tp, &to)) { isconnected = TRUE; } if (iss) { tp->iss = iss; } else { tp->iss = tcp_new_isn(tp); } tp->irs = th->th_seq; tcp_sendseqinit(tp); tcp_rcvseqinit(tp); tp->snd_recover = tp->snd_una; /* * Initialization of the tcpcb for transaction; * set SND.WND = SEG.WND, * initialize CCsend and CCrecv. */ tp->snd_wnd = tiwin; /* initial send-window */ tp->max_sndwnd = tp->snd_wnd; tp->t_flags |= TF_ACKNOW; tp->t_unacksegs = 0; tp->t_unacksegs_ce = 0; DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED); TCP_LOG_STATE(tp, TCPS_SYN_RECEIVED); tp->t_state = TCPS_SYN_RECEIVED; tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_CONN_KEEPINIT(tp)); tp->t_connect_time = tcp_now; dropsocket = 0; /* committed to socket */ if (inp->inp_flowhash == 0) { inp_calc_flowhash(inp); ASSERT(inp->inp_flowhash != 0); } /* update flowinfo - RFC 6437 */ if (inp->inp_flow == 0 && inp->in6p_flags & IN6P_AUTOFLOWLABEL) { inp->inp_flow &= ~IPV6_FLOWLABEL_MASK; inp->inp_flow |= (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK); } /* reset the incomp processing flag */ so->so_flags &= ~(SOF_INCOMP_INPROGRESS); tcpstat.tcps_accepts++; int ace_flags = ((th->th_x2 << 8) | thflags) & TH_ACE; tcp_input_process_accecn_syn(tp, ace_flags, ip_ecn); /* * The address and connection state are finalized */ TCP_LOG_CONNECT(tp, false, 0); tcp_add_fsw_flow(tp, ifp); goto trimthenstep6; } /* * If the state is SYN_RECEIVED and the seg contains an ACK, * but not for our SYN/ACK, send a RST. */ case TCPS_SYN_RECEIVED: if ((thflags & TH_ACK) && (SEQ_LEQ(th->th_ack, tp->snd_una) || SEQ_GT(th->th_ack, tp->snd_max))) { IF_TCP_STATINC(ifp, ooopacket); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_RECEIVED bad ACK"); goto dropwithreset; } /* * In SYN_RECEIVED state, if we recv some SYNS with * window scale and others without, window scaling should * be disabled. Otherwise the window advertised will be * lower if we assume scaling and the other end does not. */ if ((thflags & TH_SYN) && (tp->irs == th->th_seq) && !(to.to_flags & TOF_SCALE)) { tp->t_flags &= ~TF_RCVD_SCALE; } break; /* * If the state is SYN_SENT: * if seg contains an ACK, but not for our SYN, drop the input. * if seg contains a RST, then drop the connection. * if seg does not contain SYN, then drop it. * Otherwise this is an acceptable SYN segment * initialize tp->rcv_nxt and tp->irs * if seg contains ack then advance tp->snd_una * if SYN has been acked change to ESTABLISHED else SYN_RCVD state * arrange for segment to be acked (eventually) * continue processing rest of data/controls, beginning with URG */ case TCPS_SYN_SENT: if ((thflags & TH_ACK) && (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { IF_TCP_STATINC(ifp, ooopacket); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_SENT bad ACK"); goto dropwithreset; } if (thflags & TH_RST) { if ((thflags & TH_ACK) != 0) { if (tfo_enabled(tp) && !(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE)) { tcp_heuristic_tfo_rst(tp); } if ((tp->ecn_flags & (TE_SETUPSENT | TE_RCVD_SYN_RST)) == TE_SETUPSENT || (tp->ecn_flags & (TE_ACE_SETUPSENT | TE_RCVD_SYN_RST)) == TE_ACE_SETUPSENT) { /* * On local connections, send * non-ECN syn one time before * dropping the connection */ if (tp->t_flags & TF_LOCAL) { tp->ecn_flags |= TE_RCVD_SYN_RST; goto drop; } else { tcp_heuristic_ecn_synrst(tp); } } soevent(so, (SO_FILT_HINT_LOCKED | SO_FILT_HINT_CONNRESET)); tp = tcp_drop(tp, ECONNREFUSED); } TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_SENT got RST"); goto drop; } if ((thflags & TH_SYN) == 0) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_SENT no SYN"); goto drop; } tp->snd_wnd = th->th_win; /* initial send window */ tp->max_sndwnd = tp->snd_wnd; tp->irs = th->th_seq; tcp_rcvseqinit(tp); if (thflags & TH_ACK) { /* Client processes SYN-ACK */ tcpstat.tcps_connects++; const uint32_t ace_flags = ((th->th_x2 << 8) | thflags) & TH_ACE; if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE)) { /* Receiving Any|0|1 is classic ECN-setup SYN-ACK */ tp->ecn_flags |= TE_SETUPRECEIVED; if (TCP_ECN_ENABLED(tp)) { tcp_heuristic_ecn_success(tp); tcpstat.tcps_ecn_client_success++; } if (tp->ecn_flags & TE_ACE_SETUPSENT) { /* * Sent AccECN SYN but received classic ECN SYN-ACK * Set classic ECN related flags */ tp->ecn_flags |= (TE_SETUPSENT | TE_SENDIPECT); tp->ecn_flags &= ~TE_ACE_SETUPSENT; if (tp->t_client_accecn_state == tcp_connection_client_accurate_ecn_feature_enabled) { tp->t_client_accecn_state = tcp_connection_client_classic_ecn_available; } } } else if (TCP_ACC_ECN_ENABLED(tp) && ace_flags != 0 && ace_flags != TH_ACE) { /* Initialize sender side packet & byte counters */ tp->t_snd_ce_packets = 5; tp->t_snd_ect1_bytes = tp->t_snd_ect0_bytes = 1; tp->t_snd_ce_bytes = 0; tp->ecn_flags |= TE_ACE_FINAL_ACK_3WHS; /* * Client received AccECN SYN-ACK that reflects the state (ECN) * in which SYN packet was delivered. This helps to detect if * there was mangling of the SYN packet on the path. Currently, we * only send Not-ECT on SYN packets. So, we should set Not-ECT in * all packets if we receive any encoding other than 0|TH_CWR|0. * If 0|0|0 and 1|1|1 were received, fail Accurate ECN negotiation * by not setting TE_ACE_SETUPRECEIVED. */ switch (ace_flags) { case (0 | TH_CWR | 0): /* Non-ECT SYN was delivered */ tp->ecn_flags |= TE_ACE_SETUPRECEIVED; tcpstat.tcps_ecn_ace_syn_not_ect++; tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_negotiation_success; break; case (0 | TH_CWR | TH_ECE): /* ECT1 SYN was delivered */ tp->ecn_flags |= TE_ACE_SETUPRECEIVED; /* Mangling detected, set Non-ECT on outgoing packets */ tp->ecn_flags &= ~TE_SENDIPECT; tcpstat.tcps_ecn_ace_syn_ect1++; tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_negotiation_success_ect_mangling_detected; break; case (TH_AE | 0 | 0): /* ECT0 SYN was delivered */ tp->ecn_flags |= TE_ACE_SETUPRECEIVED; /* Mangling detected, set Non-ECT on outgoing packets */ tp->ecn_flags &= ~TE_SENDIPECT; tcpstat.tcps_ecn_ace_syn_ect0++; tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_negotiation_success_ect_mangling_detected; break; case (TH_AE | TH_CWR | 0): /* CE SYN was delivered */ tp->ecn_flags |= TE_ACE_SETUPRECEIVED; /* Mangling detected, set Non-ECT on outgoing packets */ tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_negotiation_success_ect_mangling_detected; tp->ecn_flags &= ~TE_SENDIPECT; /* * Although we don't send ECT SYN yet, it is possible that * a network element changed Not-ECT to ECT and later there * was congestion at another network element that set it to CE. * To keep it simple, we will consider this as a congestion event * for the congestion controller. * If a TCP client in AccECN mode receives CE feedback in the TCP * flags of a SYN/ACK, it MUST NOT increment s.cep. */ tcpstat.tcps_ecn_ace_syn_ce++; break; default: break; } if (TCP_ECN_ENABLED(tp)) { tcp_heuristic_ecn_success(tp); tcpstat.tcps_ecn_client_success++; } /* * A TCP client in AccECN mode MUST feed back which of the 4 * possible values of the IP-ECN field that was received in the * SYN/ACK. Set the setup flag for final ACK accordingly. * We will initialize r.cep, r.e1b, r.e0b first and then increment * if CE was set on the IP-ECN field of the SYN-ACK. */ tp->t_rcv_ce_packets = 5; tp->t_rcv_ect0_bytes = tp->t_rcv_ect1_bytes = 1; tp->t_rcv_ce_bytes = 0; /* Increment packet & byte counters based on IP-ECN */ tcp_input_ip_ecn(tp, inp, (uint32_t)tlen, (uint32_t)segment_count, ip_ecn); switch (ip_ecn) { case IPTOS_ECN_NOTECT: /* Not-ECT SYN-ACK was received */ tp->ecn_flags |= TE_ACE_SETUP_NON_ECT; break; case IPTOS_ECN_ECT1: /* ECT1 SYN-ACK was received */ tp->ecn_flags |= TE_ACE_SETUP_ECT1; break; case IPTOS_ECN_ECT0: /* ECT0 SYN-ACK was received */ tp->ecn_flags |= TE_ACE_SETUP_ECT0; break; case IPTOS_ECN_CE: tp->ecn_flags |= TE_ACE_SETUP_CE; break; } } else { if ((tp->ecn_flags & (TE_SETUPSENT | TE_ACE_SETUPSENT)) && tp->t_rxtshift == 0) { tcp_heuristic_ecn_success(tp); tcpstat.tcps_ecn_not_supported++; } if ((tp->ecn_flags & (TE_SETUPSENT | TE_ACE_SETUPSENT)) && tp->t_rxtshift > 0) { tcp_heuristic_ecn_loss(tp); } /* non-ECN-setup SYN-ACK */ tp->ecn_flags &= ~TE_SENDIPECT; /* * If Accurate ECN SYN was retransmitted twice and non-ECN SYN-ACK * was received, then we consider it as Accurate ECN blackholing */ if ((tp->ecn_flags & TE_LOST_SYN) && tp->t_rxtshift <= 2 && tp->t_client_accecn_state == tcp_connection_client_accurate_ecn_feature_enabled) { tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_negotiation_blackholed; } /* * If SYN wasn't retransmitted twice yet, the server supports neither classic nor * accurate ECN SYN-ACK. Accurate ECN should already be disabled for both half connections * as TE_ACE_SETUPRECEIVED flag is not set. */ if (tp->t_client_accecn_state == tcp_connection_client_accurate_ecn_feature_enabled) { tp->t_client_accecn_state = tcp_connection_client_ecn_not_available; } } /* Do window scaling on this connection? */ if (TCP_WINDOW_SCALE_ENABLED(tp)) { tp->snd_scale = tp->requested_s_scale; tp->rcv_scale = tp->request_r_scale; } uint32_t recwin = min(tp->rcv_wnd, TCP_MAXWIN << tp->rcv_scale); if (TCP_USE_RLEDBAT(tp, so) && tcp_cc_rledbat.get_rlwin != NULL) { /* For a LBE receiver, also use rledbat_win */ uint32_t rledbat_win = tcp_cc_rledbat.get_rlwin(tp); if (rledbat_win > 0) { recwin = min(recwin, rledbat_win); } } tp->rcv_adv += recwin; tp->snd_una++; /* SYN is acked */ if (SEQ_LT(tp->snd_nxt, tp->snd_una)) { tp->snd_nxt = tp->snd_una; } /* * We have sent more in the SYN than what is being * acked. (e.g., TFO) * We should restart the sending from what the receiver * has acknowledged immediately. */ if (SEQ_GT(tp->snd_nxt, th->th_ack)) { /* * rdar://problem/33214601 * There is a middlebox that acks all but one * byte and still drops the data. */ if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) && (tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) && tp->snd_max == th->th_ack + 1 && tp->snd_max > tp->snd_una + 1) { tcp_heuristic_tfo_middlebox(tp); so->so_error = ENODATA; soevent(so, (SO_FILT_HINT_LOCKED | SO_FILT_HINT_MP_SUB_ERROR)); tp->t_tfo_stats |= TFO_S_ONE_BYTE_PROXY; } tp->snd_max = tp->snd_nxt = th->th_ack; } /* * If there's data, delay ACK; if there's also a FIN * ACKNOW will be turned on later. */ TCP_INC_VAR(tp->t_unacksegs, segment_count); if (TCP_ACC_ECN_ON(tp) && ip_ecn == IPTOS_ECN_CE) { TCP_INC_VAR(tp->t_unacksegs_ce, segment_count); } if (DELAY_ACK(tp, th) && tlen != 0) { if ((tp->t_flags & TF_DELACK) == 0) { tp->t_flags |= TF_DELACK; tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack); } } else { tp->t_flags |= TF_ACKNOW; } /* * Received in SYN_SENT[*] state. * Transitions: * SYN_SENT --> ESTABLISHED * SYN_SENT* --> FIN_WAIT_1 */ tp->t_starttime = tcp_now; tcp_sbrcv_tstmp_check(tp); if (tp->t_flags & TF_NEEDFIN) { DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_1); TCP_LOG_STATE(tp, TCPS_FIN_WAIT_1); tp->t_state = TCPS_FIN_WAIT_1; tp->t_flags &= ~TF_NEEDFIN; thflags &= ~TH_SYN; TCP_LOG_CONNECTION_SUMMARY(tp); } else { DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_ESTABLISHED); TCP_LOG_STATE(tp, TCPS_ESTABLISHED); tp->t_state = TCPS_ESTABLISHED; tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_CONN_KEEPIDLE(tp)); if (nstat_collect) { nstat_route_connect_success( inp->inp_route.ro_rt); } TCP_LOG_CONNECTED(tp, 0); /* * The SYN is acknowledged but una is not * updated yet. So pass the value of * ack to compute sndbytes correctly */ inp_count_sndbytes(inp, th->th_ack); } tp->t_forced_acks = TCP_FORCED_ACKS_COUNT; #if MPTCP /* * Do not send the connect notification for additional * subflows until ACK for 3-way handshake arrives. */ if ((!(tp->t_mpflags & TMPF_MPTCP_TRUE)) && (tp->t_mpflags & TMPF_SENT_JOIN)) { isconnected = FALSE; } else #endif /* MPTCP */ isconnected = TRUE; if ((tp->t_tfo_flags & (TFO_F_COOKIE_REQ | TFO_F_COOKIE_SENT)) || (tp->t_tfo_stats & TFO_S_SYN_DATA_SENT)) { tcp_tfo_synack(tp, &to); if ((tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) && SEQ_LT(tp->snd_una, th->th_ack)) { tp->t_tfo_stats |= TFO_S_SYN_DATA_ACKED; tcpstat.tcps_tfo_syn_data_acked++; #if MPTCP if (so->so_flags & SOF_MP_SUBFLOW) { so->so_flags1 |= SOF1_TFO_REWIND; } #endif tcp_tfo_rcv_probe(tp, tlen); } } } else { /* * Received initial SYN in SYN-SENT[*] state => simul- * taneous open. * Do 3-way handshake: * SYN-SENT -> SYN-RECEIVED * SYN-SENT* -> SYN-RECEIVED* */ tp->t_flags |= TF_ACKNOW; tp->t_timer[TCPT_REXMT] = 0; DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED); TCP_LOG_STATE(tp, TCPS_SYN_RECEIVED); tp->t_state = TCPS_SYN_RECEIVED; /* * During simultaneous open, TFO should not be used. * So, we disable it here, to prevent that data gets * sent on the SYN/ACK. */ tcp_disable_tfo(tp); } trimthenstep6: /* * Advance th->th_seq to correspond to first data byte. * If data, trim to stay within window, * dropping FIN if necessary. */ th->th_seq++; if (tlen > tp->rcv_wnd) { todrop = tlen - tp->rcv_wnd; m_adj(m, -todrop); tlen = tp->rcv_wnd; thflags &= ~TH_FIN; tcpstat.tcps_rcvpackafterwin++; tcpstat.tcps_rcvbyteafterwin += todrop; } tp->snd_wl1 = th->th_seq - 1; tp->rcv_up = th->th_seq; /* * Client side of transaction: already sent SYN and data. * If the remote host used T/TCP to validate the SYN, * our data will be ACK'd; if so, enter normal data segment * processing in the middle of step 5, ack processing. * Otherwise, goto step 6. */ if (thflags & TH_ACK) { goto process_ACK; } goto step6; /* * If the state is LAST_ACK or CLOSING or TIME_WAIT: * do normal processing. * * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. */ case TCPS_LAST_ACK: case TCPS_CLOSING: case TCPS_TIME_WAIT: break; /* continue normal processing */ /* Received a SYN while connection is already established. * This is a "half open connection and other anomalies" described * in RFC793 page 34, send an ACK so the remote reset the connection * or recovers by adjusting its sequence numbering. Sending an ACK is * in accordance with RFC 5961 Section 4.2 * * For Accurate ECN, if we receive a packet with SYN in ESTABLISHED * state, we don't send the handshake encoding. */ case TCPS_ESTABLISHED: if (thflags & TH_SYN && tlen <= 0) { /* Drop the packet silently if we have reached the limit */ if (tcp_is_ack_ratelimited(tp)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 rate limited"); goto drop; } else { /* Send challenge ACK */ tcpstat.tcps_synchallenge++; TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 challenge ACK"); goto dropafterack; } } break; } /* * States other than LISTEN or SYN_SENT. * First check the RST flag and sequence number since reset segments * are exempt from the timestamp and connection count tests. This * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix * below which allowed reset segments in half the sequence space * to fall though and be processed (which gives forged reset * segments with a random sequence number a 50 percent chance of * killing a connection). * Then check timestamp, if present. * Then check the connection count, if present. * Then check that at least some bytes of segment are within * receive window. If segment begins before rcv_nxt, * drop leading data (and SYN); if nothing left, just ack. * * * If the RST bit is set, check the sequence number to see * if this is a valid reset segment. * RFC 793 page 37: * In all states except SYN-SENT, all reset (RST) segments * are validated by checking their SEQ-fields. A reset is * valid if its sequence number is in the window. * Note: this does not take into account delayed ACKs, so * we should test against last_ack_sent instead of rcv_nxt. * The sequence number in the reset segment is normally an * echo of our outgoing acknowlegement numbers, but some hosts * send a reset with the sequence number at the rightmost edge * of our receive window, and we have to handle this case. * Note 2: Paul Watson's paper "Slipping in the Window" has shown * that brute force RST attacks are possible. To combat this, * we use a much stricter check while in the ESTABLISHED state, * only accepting RSTs where the sequence number is equal to * last_ack_sent. In all other states (the states in which a * RST is more likely), the more permissive check is used. * RFC 5961 Section 3.2: if the RST bit is set, sequence # is * within the receive window and last_ack_sent == seq, * then reset the connection. Otherwise if the seq doesn't * match last_ack_sent, TCP must send challenge ACK. Perform * rate limitation when sending the challenge ACK. * If we have multiple segments in flight, the intial reset * segment sequence numbers will be to the left of last_ack_sent, * but they will eventually catch up. * In any case, it never made sense to trim reset segments to * fit the receive window since RFC 1122 says: * 4.2.2.12 RST Segment: RFC-793 Section 3.4 * * A TCP SHOULD allow a received RST segment to include data. * * DISCUSSION * It has been suggested that a RST segment could contain * ASCII text that encoded and explained the cause of the * RST. No standard has yet been established for such * data. * * If the reset segment passes the sequence number test examine * the state: * SYN_RECEIVED STATE: * If passive open, return to LISTEN state. * If active open, inform user that connection was refused. * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES: * Inform user that connection was reset, and close tcb. * CLOSING, LAST_ACK STATES: * Close the tcb. * TIME_WAIT STATE: * Drop the segment - see Stevens, vol. 2, p. 964 and * RFC 1337. * * Radar 4803931: Allows for the case where we ACKed the FIN but * there is already a RST in flight from the peer. * In that case, accept the RST for non-established * state if it's one off from last_ack_sent. * */ if (thflags & TH_RST) { if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || (tp->rcv_wnd == 0 && ((tp->last_ack_sent == th->th_seq) || ((tp->last_ack_sent - 1) == th->th_seq)))) { if (tp->last_ack_sent == th->th_seq) { switch (tp->t_state) { case TCPS_SYN_RECEIVED: IF_TCP_STATINC(ifp, rstinsynrcv); so->so_error = ECONNREFUSED; goto close; case TCPS_ESTABLISHED: if ((TCP_ECN_ENABLED(tp) || TCP_ACC_ECN_ON(tp)) && tp->snd_una == tp->iss + 1 && SEQ_GT(tp->snd_max, tp->snd_una)) { /* * If the first data packet on an * ECN connection, receives a RST * increment the heuristic */ tcp_heuristic_ecn_droprst(tp); } OS_FALLTHROUGH; case TCPS_FIN_WAIT_1: case TCPS_CLOSE_WAIT: case TCPS_FIN_WAIT_2: so->so_error = ECONNRESET; close: soevent(so, (SO_FILT_HINT_LOCKED | SO_FILT_HINT_CONNRESET)); tcpstat.tcps_drops++; tp = tcp_close(tp); break; case TCPS_CLOSING: case TCPS_LAST_ACK: tp = tcp_close(tp); break; case TCPS_TIME_WAIT: break; } } else { tcpstat.tcps_badrst++; /* Drop if we have reached the ACK limit */ if (tcp_is_ack_ratelimited(tp)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 rate limited"); goto drop; } else { /* Send challenge ACK */ tcpstat.tcps_rstchallenge++; TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 challenge ACK"); goto dropafterack; } } } goto drop; } /* * 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)) { /* Check to see if ts_recent is over 24 days old. */ if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) { /* * Invalidate ts_recent. If this segment updates * ts_recent, the age will be reset later and ts_recent * will get a valid value. If it does not, setting * ts_recent to zero will at least satisfy the * requirement that zero be placed in the timestamp * echo reply when ts_recent isn't valid. The * age isn't reset until we get a valid ts_recent * because we don't want out-of-order segments to be * dropped when ts_recent is old. */ tp->ts_recent = 0; } else { tcpstat.tcps_rcvduppack++; tcpstat.tcps_rcvdupbyte += tlen; tp->t_pawsdrop++; tcpstat.tcps_pawsdrop++; /* * PAWS-drop when ECN is being used? That indicates * that ECT-marked packets take a different path, with * different congestion-characteristics. * * Only fallback when we did send less than 2GB as PAWS * really has no reason to kick in earlier. */ if ((TCP_ECN_ENABLED(tp) || TCP_ACC_ECN_ON(tp)) && inp->inp_stat->rxbytes < 2147483648) { INP_INC_IFNET_STAT(inp, ecn_fallback_reorder); tcpstat.tcps_ecn_fallback_reorder++; tcp_heuristic_ecn_aggressive(tp); } if (nstat_collect) { nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, tlen, NSTAT_RX_FLAG_DUPLICATE); INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, tlen); tp->t_stat.rxduplicatebytes += tlen; inp_set_activity_bitmap(inp); } if (tlen > 0) { goto dropafterack; } goto drop; } } /* * In the SYN-RECEIVED state, validate that the packet belongs to * this connection before trimming the data to fit the receive * window. Check the sequence number versus IRS since we know * the sequence numbers haven't wrapped. This is a partial fix * for the "LAND" DoS attack. */ if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { IF_TCP_STATINC(ifp, dospacket); TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_RECEIVED bad SEQ"); goto dropwithreset; } /* * Check if there is old data at the beginning of the window * i.e. the sequence number is before rcv_nxt */ todrop = tp->rcv_nxt - th->th_seq; if (todrop > 0) { boolean_t is_syn_set = FALSE; if (thflags & TH_SYN) { is_syn_set = TRUE; thflags &= ~TH_SYN; th->th_seq++; if (th->th_urp > 1) { th->th_urp--; } else { thflags &= ~TH_URG; } todrop--; } /* * Following if statement from Stevens, vol. 2, p. 960. * The amount of duplicate data is greater than or equal * to the size of the segment - entire segment is duplicate */ if (todrop > tlen || (todrop == tlen && (thflags & TH_FIN) == 0)) { /* * Any valid FIN must be to the left of the window. * At this point the FIN must be a duplicate or out * of sequence; drop it. */ thflags &= ~TH_FIN; /* * Send an ACK to resynchronize and drop any data. * But keep on processing for RST or ACK. * * If the SYN bit was originally set, then only send * an ACK if we are not rate-limiting this connection. */ if (is_syn_set) { if (!tcp_is_ack_ratelimited(tp)) { tcpstat.tcps_synchallenge++; tp->t_flags |= TF_ACKNOW; } } else { tp->t_flags |= TF_ACKNOW; } if (todrop == 1) { /* This could be a keepalive */ soevent(so, SO_FILT_HINT_LOCKED | SO_FILT_HINT_KEEPALIVE); } todrop = tlen; tcpstat.tcps_rcvduppack++; tcpstat.tcps_rcvdupbyte += todrop; } else { tcpstat.tcps_rcvpartduppack++; tcpstat.tcps_rcvpartdupbyte += todrop; } if (todrop > 1) { /* * Note the duplicate data sequence space so that * it can be reported in DSACK option. */ tp->t_dsack_lseq = th->th_seq; tp->t_dsack_rseq = th->th_seq + todrop; tp->t_flags |= TF_ACKNOW; } if (nstat_collect) { nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, todrop, NSTAT_RX_FLAG_DUPLICATE); INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, todrop); tp->t_stat.rxduplicatebytes += todrop; inp_set_activity_bitmap(inp); } drop_hdrlen += todrop; /* drop from the top afterwards */ th->th_seq += todrop; tlen -= todrop; if (th->th_urp > todrop) { th->th_urp -= todrop; } else { thflags &= ~TH_URG; th->th_urp = 0; } } /* * If new data are received on a connection after the user * processes are gone, then RST the other end. * Send also a RST when we received a data segment after we've * sent our FIN when the socket is defunct. * Note that an MPTCP subflow socket would have SS_NOFDREF set * by default. So, if it's an MPTCP-subflow we rather check the * MPTCP-level's socket state for SS_NOFDREF. */ if (tlen) { boolean_t close_it = FALSE; if (!(so->so_flags & SOF_MP_SUBFLOW) && (so->so_state & SS_NOFDREF) && tp->t_state > TCPS_CLOSE_WAIT) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SS_NOFDREF"); close_it = TRUE; } if ((so->so_flags & SOF_MP_SUBFLOW) && (mptetoso(tptomptp(tp)->mpt_mpte)->so_state & SS_NOFDREF) && tp->t_state > TCPS_CLOSE_WAIT) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SOF_MP_SUBFLOW SS_NOFDREF"); close_it = TRUE; } if ((so->so_flags & SOF_DEFUNCT) && tp->t_state > TCPS_FIN_WAIT_1) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SOF_DEFUNCT"); close_it = TRUE; } if (so->so_state & SS_CANTRCVMORE) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SS_CANTRCVMORE"); close_it = TRUE; } if (close_it) { tp = tcp_close(tp); tcpstat.tcps_rcvafterclose++; IF_TCP_STATINC(ifp, cleanup); goto dropwithreset; } } /* * If segment ends after window, drop trailing data * (and PUSH and FIN); if nothing left, just ACK. */ todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); if (todrop > 0) { tcpstat.tcps_rcvpackafterwin++; if (todrop >= tlen) { tcpstat.tcps_rcvbyteafterwin += tlen; /* * 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 && tp->t_state == TCPS_TIME_WAIT && SEQ_GT(th->th_seq, tp->rcv_nxt)) { iss = tcp_new_isn(tp); tp = tcp_close(tp); socket_unlock(so, 1); goto findpcb; } /* * If window is closed can only take segments at * window edge, and have to drop data and PUSH from * incoming segments. Continue processing, but * remember to ack. Otherwise, drop segment * and ack. */ if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { tp->t_flags |= TF_ACKNOW; tcpstat.tcps_rcvwinprobe++; } else { goto dropafterack; } } else { tcpstat.tcps_rcvbyteafterwin += todrop; } m_adj(m, -todrop); tlen -= todrop; thflags &= ~(TH_PUSH | TH_FIN); } /* * If last ACK falls within this segment's sequence numbers, * record its timestamp. * NOTE: * 1) That the test incorporates suggestions from the latest * proposal of the tcplw@cray.com list (Braden 1993/04/26). * 2) That updating only on newer timestamps interferes with * our earlier PAWS tests, so this check should be solely * predicated on the sequence space of this segment. * 3) That we modify the segment boundary check to be * Last.ACK.Sent <= SEG.SEQ + SEG.Len * instead of RFC1323's * Last.ACK.Sent < SEG.SEQ + SEG.Len, * This modified check allows us to overcome RFC1323's * limitations as described in Stevens TCP/IP Illustrated * Vol. 2 p.869. In such cases, we can still calculate the * RTT correctly when RCV.NXT == Last.ACK.Sent. */ if ((to.to_flags & TOF_TS) != 0 && SEQ_LEQ(th->th_seq, tp->last_ack_sent) && SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + ((thflags & (TH_SYN | TH_FIN)) != 0))) { tp->ts_recent_age = tcp_now; tp->ts_recent = to.to_tsval; } /* * Stevens: If a SYN is in the window, then this is an * error and we send an RST and drop the connection. * * RFC 5961 Section 4.2 * Send challenge ACK for any SYN in synchronized state * Perform rate limitation in doing so. */ if (thflags & TH_SYN) { if (!tcp_syn_data_valid(tp, th, tlen)) { tcpstat.tcps_badsyn++; /* Drop if we have reached ACK limit */ if (tcp_is_ack_ratelimited(tp)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 bad SYN rate limited"); goto drop; } else { /* Send challenge ACK */ tcpstat.tcps_synchallenge++; TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 bad SYN challenge ack"); goto dropafterack; } } else { /* * Received SYN (/ACK) with data. * Move sequence number along to process the data. */ th->th_seq++; thflags &= ~TH_SYN; } } /* * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN * flag is on (half-synchronized state), then queue data for * later processing; else drop segment and return. */ if ((thflags & TH_ACK) == 0) { if (tp->t_state == TCPS_SYN_RECEIVED) { if ((tfo_enabled(tp))) { /* * So, we received a valid segment while in * SYN-RECEIVED. * As this cannot be an RST (see that if a bit * higher), and it does not have the ACK-flag * set, we want to retransmit the SYN/ACK. * Thus, we have to reset snd_nxt to snd_una to * trigger the going back to sending of the * SYN/ACK. This is more consistent with the * behavior of tcp_output(), which expects * to send the segment that is pointed to by * snd_nxt. */ tp->snd_nxt = tp->snd_una; /* * We need to make absolutely sure that we are * going to reply upon a duplicate SYN-segment. */ if (th->th_flags & TH_SYN) { needoutput = 1; } } /* Process this same as newly received Accurate ECN SYN */ int ace_flags = ((th->th_x2 << 8) | thflags) & TH_ACE; tcp_input_process_accecn_syn(tp, ace_flags, ip_ecn); goto step6; } else if (tp->t_flags & TF_ACKNOW) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad ACK"); goto dropafterack; } else { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad ACK"); goto drop; } } /* * Ack processing. */ switch (tp->t_state) { /* * In SYN_RECEIVED state, the ack ACKs our SYN, so enter * ESTABLISHED state and continue processing. * The ACK was checked above. */ case TCPS_SYN_RECEIVED: tcpstat.tcps_connects++; /* Do window scaling? */ if (TCP_WINDOW_SCALE_ENABLED(tp)) { tp->snd_scale = tp->requested_s_scale; tp->rcv_scale = tp->request_r_scale; tp->snd_wnd = th->th_win << tp->snd_scale; tp->max_sndwnd = tp->snd_wnd; tiwin = tp->snd_wnd; } /* * Make transitions: * SYN-RECEIVED -> ESTABLISHED * SYN-RECEIVED* -> FIN-WAIT-1 */ tp->t_starttime = tcp_now; tcp_sbrcv_tstmp_check(tp); if (tp->t_flags & TF_NEEDFIN) { DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_1); TCP_LOG_STATE(tp, TCPS_FIN_WAIT_1); tp->t_state = TCPS_FIN_WAIT_1; tp->t_flags &= ~TF_NEEDFIN; TCP_LOG_CONNECTION_SUMMARY(tp); } else { DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_ESTABLISHED); TCP_LOG_STATE(tp, TCPS_ESTABLISHED); tp->t_state = TCPS_ESTABLISHED; tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, TCP_CONN_KEEPIDLE(tp)); if (nstat_collect) { nstat_route_connect_success( tp->t_inpcb->inp_route.ro_rt); } TCP_LOG_CONNECTED(tp, 0); /* * The SYN is acknowledged but una is not updated * yet. So pass the value of ack to compute * sndbytes correctly */ inp_count_sndbytes(inp, th->th_ack); } tp->t_forced_acks = TCP_FORCED_ACKS_COUNT; VERIFY(LIST_EMPTY(&tp->t_segq)); tp->snd_wl1 = th->th_seq - 1; /* * AccECN server in SYN-RCVD state received an ACK with * SYN=0, process handshake encoding present in the ACK for SYN-ACK * and update receive side counters. */ if (TCP_ACC_ECN_ON(tp) && (thflags & (TH_SYN | TH_ACK)) == TH_ACK) { const uint32_t ace_flags = ((th->th_x2 << 8) | thflags) & TH_ACE; if (tlen == 0 && to.to_nsacks == 0) { /* * ACK for SYN-ACK reflects the state (ECN) in which SYN-ACK packet * was delivered. Use Table 4 of Accurate ECN draft to decode only * when a pure ACK with no SACK block is received. * 0|0|0 will fail Accurate ECN negotiation and disable ECN. */ switch (ace_flags) { case (0 | TH_CWR | 0): /* Non-ECT SYN-ACK was delivered */ tp->t_snd_ce_packets = 5; if (tp->t_server_accecn_state == tcp_connection_server_accurate_ecn_requested) { tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_negotiation_success; } break; case (0 | TH_CWR | TH_ECE): /* ECT1 SYN-ACK was delivered, mangling detected */ OS_FALLTHROUGH; case (TH_AE | 0 | 0): /* ECT0 SYN-ACK was delivered, mangling detected */ tp->t_snd_ce_packets = 5; if (tp->t_server_accecn_state == tcp_connection_server_accurate_ecn_requested) { tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_negotiation_success_ect_mangling_detected; } break; case (TH_AE | TH_CWR | 0): /* * CE SYN-ACK was delivered, even though mangling happened, * CE could indicate congestion at a node after mangling occured. * Set cwnd to 2 segments */ tp->t_snd_ce_packets = 6; tp->snd_cwnd = 2 * tp->t_maxseg; if (tp->t_server_accecn_state == tcp_connection_server_accurate_ecn_requested) { tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_negotiation_success_ect_mangling_detected; } break; case (0 | 0 | 0): /* Disable ECN, as ACE fields were zeroed */ tp->ecn_flags &= ~(TE_SETUPRECEIVED | TE_SENDIPECT | TE_SENDCWR | TE_ACE_SETUPRECEIVED); /* * Since last ACK has no ECN flag set and TE_LOST_SYNACK is set, this is in response * to the second (non-ECN setup) SYN-ACK retransmission. In such a case, we assume * that AccECN SYN-ACK was blackholed. */ if ((tp->ecn_flags & TE_LOST_SYNACK) && tp->t_rxtshift <= 2 && (tp->t_server_accecn_state == tcp_connection_server_classic_ecn_requested || tp->t_server_accecn_state == tcp_connection_server_accurate_ecn_requested)) { tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_negotiation_blackholed; } /* * SYN-ACK hasn't been retransmitted twice yet, so this could likely mean bleaching of ACE * on the path from client to server on last ACK. */ if (tp->t_server_accecn_state == tcp_connection_server_accurate_ecn_requested) { tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_ace_bleaching_detected; } break; default: /* Unused values for forward compatibility */ tp->t_snd_ce_packets = 5; break; } } /* Increment receive side counters based on IP-ECN */ tcp_input_ip_ecn(tp, inp, (uint32_t)tlen, (uint32_t)segment_count, ip_ecn); } #if MPTCP /* * Do not send the connect notification for additional subflows * until ACK for 3-way handshake arrives. */ if ((!(tp->t_mpflags & TMPF_MPTCP_TRUE)) && (tp->t_mpflags & TMPF_SENT_JOIN)) { isconnected = FALSE; } else #endif /* MPTCP */ isconnected = TRUE; if ((tp->t_tfo_flags & TFO_F_COOKIE_VALID)) { /* Done this when receiving the SYN */ isconnected = FALSE; OSDecrementAtomic(&tcp_tfo_halfcnt); /* Panic if something has gone terribly wrong. */ VERIFY(tcp_tfo_halfcnt >= 0); tp->t_tfo_flags &= ~TFO_F_COOKIE_VALID; } /* * In case there is data in the send-queue (e.g., TFO is being * used, or connectx+data has been done), then if we would * "FALLTHROUGH", we would handle this ACK as if data has been * acknowledged. But, we have to prevent this. And this * can be prevented by increasing snd_una by 1, so that the * SYN is not considered as data (snd_una++ is actually also * done in SYN_SENT-state as part of the regular TCP stack). * * In case there is data on this ack as well, the data will be * handled by the label "dodata" right after step6. */ if (so->so_snd.sb_cc) { tp->snd_una++; /* SYN is acked */ if (SEQ_LT(tp->snd_nxt, tp->snd_una)) { tp->snd_nxt = tp->snd_una; } /* * No duplicate-ACK handling is needed. So, we * directly advance to processing the ACK (aka, * updating the RTT estimation,...) * * But, we first need to handle eventual SACKs, * because TFO will start sending data with the * SYN/ACK, so it might be that the client * includes a SACK with its ACK. */ if (SACK_ENABLED(tp) && (to.to_nsacks > 0 || !TAILQ_EMPTY(&tp->snd_holes))) { tcp_sack_doack(tp, &to, th, &sack_bytes_acked, &sack_bytes_newly_acked); } goto process_ACK; } OS_FALLTHROUGH; /* * In ESTABLISHED state: drop duplicate ACKs; ACK out of range * ACKs. If the ack is in the range * tp->snd_una < th->th_ack <= tp->snd_max * then advance tp->snd_una to th->th_ack and drop * data from the retransmission queue. If this ACK reflects * more up to date window information we update our window information. */ case TCPS_ESTABLISHED: case TCPS_FIN_WAIT_1: case TCPS_FIN_WAIT_2: case TCPS_CLOSE_WAIT: case TCPS_CLOSING: case TCPS_LAST_ACK: case TCPS_TIME_WAIT: if (SEQ_GT(th->th_ack, tp->snd_max)) { tcpstat.tcps_rcvacktoomuch++; if (tcp_is_ack_ratelimited(tp)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 rcvacktoomuch"); goto drop; } else { goto dropafterack; } } if (SEQ_LT(th->th_ack, tp->snd_una - tp->max_sndwnd)) { if (tcp_is_ack_ratelimited(tp)) { TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 bad ACK"); goto drop; } else { goto dropafterack; } } if (SACK_ENABLED(tp) && to.to_nsacks > 0) { recvd_dsack = tcp_sack_process_dsack(tp, &to, th); /* * If DSACK is received and this packet has no * other SACK information, it can be dropped. * We do not want to treat it as a duplicate ack. */ if (recvd_dsack && SEQ_LEQ(th->th_ack, tp->snd_una) && to.to_nsacks == 0) { tcp_bad_rexmt_check(tp, th, &to); goto drop; } } if (SACK_ENABLED(tp) && (to.to_nsacks > 0 || !TAILQ_EMPTY(&tp->snd_holes))) { tcp_sack_doack(tp, &to, th, &sack_bytes_acked, &sack_bytes_newly_acked); } #if MPTCP if (tp->t_mpuna && SEQ_GEQ(th->th_ack, tp->t_mpuna)) { if (tp->t_mpflags & TMPF_PREESTABLISHED) { /* MP TCP establishment succeeded */ tp->t_mpuna = 0; if (tp->t_mpflags & TMPF_JOINED_FLOW) { if (tp->t_mpflags & TMPF_SENT_JOIN) { tp->t_mpflags &= ~TMPF_PREESTABLISHED; tp->t_mpflags |= TMPF_MPTCP_TRUE; tp->t_timer[TCPT_JACK_RXMT] = 0; tp->t_mprxtshift = 0; isconnected = TRUE; } else { isconnected = FALSE; } } else { isconnected = TRUE; } } } #endif /* MPTCP */ tcp_tfo_rcv_ack(tp, th); /* * If we have outstanding data (other than * a window probe), this is a completely * duplicate ack and the ack is the biggest we've seen. * * Need to accommodate a change in window on duplicate acks * to allow operating systems that update window during * recovery with SACK */ if (SEQ_LEQ(th->th_ack, tp->snd_una)) { if (tlen == 0 && (tiwin == tp->snd_wnd || (to.to_nsacks > 0 && sack_bytes_acked > 0))) { uint32_t old_dupacks; /* * If both ends send FIN at the same time, * then the ack will be a duplicate ack * but we have to process the FIN. Check * for this condition and process the FIN * instead of the dupack */ if ((thflags & TH_FIN) && !TCPS_HAVERCVDFIN(tp->t_state)) { break; } process_dupack: old_dupacks = tp->t_dupacks; #if MPTCP /* * MPTCP options that are ignored must * not be treated as duplicate ACKs. */ if (to.to_flags & TOF_MPTCP) { goto drop; } if ((isconnected) && (tp->t_mpflags & TMPF_JOINED_FLOW)) { break; } #endif /* MPTCP */ /* * If a duplicate acknowledgement was seen * after ECN, it indicates packet loss in * addition to ECN. Reset INRECOVERY flag * so that we can process partial acks * correctly */ if (tp->ecn_flags & TE_INRECOVERY) { tp->ecn_flags &= ~TE_INRECOVERY; } tcpstat.tcps_rcvdupack++; if (SACK_ENABLED(tp) && tcp_do_better_lr) { tp->t_dupacks += max(1, sack_bytes_acked / tp->t_maxseg); } else { ++tp->t_dupacks; } tp->sackhint.sack_bytes_acked += sack_bytes_acked; if (SACK_ENABLED(tp) && tcp_do_better_lr) { tp->t_new_dupacks += (sack_bytes_newly_acked / tp->t_maxseg); if (tp->t_new_dupacks >= tp->t_rexmtthresh && IN_FASTRECOVERY(tp)) { /* Let's restart the retransmission */ tcp_sack_lost_rexmit(tp); /* * If the current tcp cc module has * defined a hook for tasks to run * before entering FR, call it */ if (CC_ALGO(tp)->pre_fr != NULL) { CC_ALGO(tp)->pre_fr(tp); } ENTER_FASTRECOVERY(tp); if (tp->t_flags & TF_SENTFIN) { tp->snd_recover = tp->snd_max - 1; } else { tp->snd_recover = tp->snd_max; } tp->t_rtttime = 0; /* * Accurate ECN Sender MUST NOT set CWR to indicate * it has received and responded to indications * of congestion. ACE field is used to reflect counters * that are continously updated overloading the CWR bit. */ if (!TCP_ACC_ECN_ON(tp) && TCP_ECN_ENABLED(tp)) { tp->ecn_flags |= TE_SENDCWR; } if (tp->t_flagsext & TF_CWND_NONVALIDATED) { tcp_cc_adjust_nonvalidated_cwnd(tp); } else { tp->snd_cwnd = tp->snd_ssthresh; } } } /* * Check if we need to reset the limit on * early retransmit */ if (tp->t_early_rexmt_count > 0 && TSTMP_GEQ(tcp_now, (tp->t_early_rexmt_win + TCP_EARLY_REXMT_WIN))) { tp->t_early_rexmt_count = 0; } /* * Is early retransmit needed? We check for * this when the connection is waiting for * duplicate acks to enter fast recovery. */ if (!IN_FASTRECOVERY(tp)) { tcp_early_rexmt_check(tp, th); } /* * If we've seen exactly rexmt threshold * of duplicate acks, assume a packet * has been dropped and retransmit it. * Kludge snd_nxt & the congestion * window so we send only this one * packet. * * We know we're losing at the current * window size so do congestion avoidance * (set ssthresh to half the current window * and pull our congestion window back to * the new ssthresh). * * Dup acks mean that packets have left the * network (they're now cached at the receiver) * so bump cwnd by the amount in the receiver * to keep a constant cwnd packets in the * network. */ if (tp->t_timer[TCPT_REXMT] == 0 || (th->th_ack != tp->snd_una && sack_bytes_acked == 0)) { tp->t_dupacks = 0; tp->t_rexmtthresh = tcprexmtthresh; tp->t_new_dupacks = 0; } else if ((tp->t_dupacks > tp->t_rexmtthresh && (!tcp_do_better_lr || old_dupacks >= tp->t_rexmtthresh)) || IN_FASTRECOVERY(tp)) { /* * If this connection was seeing packet * reordering, then recovery might be * delayed to disambiguate between * reordering and loss */ if (SACK_ENABLED(tp) && !IN_FASTRECOVERY(tp) && (tp->t_flagsext & (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) == (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) { /* * Since the SACK information is already * updated, this ACK will be dropped */ break; } /* * Dup acks mean that packets have left the * network (they're now cached at the receiver) * so bump cwnd by the amount in the receiver * to keep a constant cwnd packets in the * network. */ if (SACK_ENABLED(tp) && IN_FASTRECOVERY(tp)) { int awnd; /* * Compute the amount of data in flight first. * We can inject new data into the pipe iff * we have less than snd_ssthres worth of data in * flight. */ awnd = (tp->snd_nxt - tp->snd_fack) + tp->sackhint.sack_bytes_rexmit; if (awnd < tp->snd_ssthresh) { tp->snd_cwnd += tp->t_maxseg; if (tp->snd_cwnd > tp->snd_ssthresh) { tp->snd_cwnd = tp->snd_ssthresh; } } } else { tp->snd_cwnd += tp->t_maxseg; } /* Process any window updates */ if (tiwin > tp->snd_wnd) { tcp_update_window(tp, thflags, th, tiwin, tlen); } tcp_ccdbg_trace(tp, th, TCP_CC_IN_FASTRECOVERY); (void) tcp_output(tp); goto drop; } else if ((!tcp_do_better_lr && tp->t_dupacks == tp->t_rexmtthresh) || (tcp_do_better_lr && tp->t_dupacks >= tp->t_rexmtthresh)) { tcp_seq onxt = tp->snd_nxt; /* * If we're doing sack, check to * see if we're already in sack * recovery. If we're not doing sack, * check to see if we're in newreno * recovery. */ if (SACK_ENABLED(tp)) { if (IN_FASTRECOVERY(tp)) { tp->t_dupacks = 0; break; } else if (tp->t_flagsext & TF_DELAY_RECOVERY) { break; } } else { if (SEQ_LEQ(th->th_ack, tp->snd_recover)) { tp->t_dupacks = 0; break; } } if (tp->t_flags & TF_SENTFIN) { tp->snd_recover = tp->snd_max - 1; } else { tp->snd_recover = tp->snd_max; } tp->t_timer[TCPT_PTO] = 0; tp->t_rtttime = 0; /* * If the connection has seen pkt * reordering, delay recovery until * it is clear that the packet * was lost. */ if (SACK_ENABLED(tp) && (tp->t_flagsext & (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) == TF_PKTS_REORDERED && !IN_FASTRECOVERY(tp) && tp->t_reorderwin > 0 && (tp->t_state == TCPS_ESTABLISHED || tp->t_state == TCPS_FIN_WAIT_1)) { tp->t_timer[TCPT_DELAYFR] = OFFSET_FROM_START(tp, tp->t_reorderwin); tp->t_flagsext |= TF_DELAY_RECOVERY; tcpstat.tcps_delay_recovery++; tcp_ccdbg_trace(tp, th, TCP_CC_DELAY_FASTRECOVERY); break; } tcp_rexmt_save_state(tp); /* * If the current tcp cc module has * defined a hook for tasks to run * before entering FR, call it */ if (CC_ALGO(tp)->pre_fr != NULL) { CC_ALGO(tp)->pre_fr(tp); } ENTER_FASTRECOVERY(tp); tp->t_timer[TCPT_REXMT] = 0; if (!TCP_ACC_ECN_ON(tp) && TCP_ECN_ENABLED(tp)) { tp->ecn_flags |= TE_SENDCWR; } if (SACK_ENABLED(tp)) { tcpstat.tcps_sack_recovery_episode++; tp->t_sack_recovery_episode++; tp->sack_newdata = tp->snd_nxt; if (tcp_do_better_lr) { tp->snd_cwnd = tp->snd_ssthresh; } else { tp->snd_cwnd = tp->t_maxseg; } tp->t_flagsext &= ~TF_CWND_NONVALIDATED; /* Process any window updates */ if (tiwin > tp->snd_wnd) { tcp_update_window(tp, thflags, th, tiwin, tlen); } tcp_ccdbg_trace(tp, th, TCP_CC_ENTER_FASTRECOVERY); (void) tcp_output(tp); goto drop; } tp->snd_nxt = th->th_ack; tp->snd_cwnd = tp->t_maxseg; /* Process any window updates */ if (tiwin > tp->snd_wnd) { tcp_update_window(tp, thflags, th, tiwin, tlen); } (void) tcp_output(tp); if (tp->t_flagsext & TF_CWND_NONVALIDATED) { tcp_cc_adjust_nonvalidated_cwnd(tp); } else { tp->snd_cwnd = tp->snd_ssthresh + tp->t_maxseg * tp->t_dupacks; } if (SEQ_GT(onxt, tp->snd_nxt)) { tp->snd_nxt = onxt; } tcp_ccdbg_trace(tp, th, TCP_CC_ENTER_FASTRECOVERY); goto drop; } else if (ALLOW_LIMITED_TRANSMIT(tp) && (!(SACK_ENABLED(tp)) || sack_bytes_acked > 0) && (so->so_snd.sb_cc - (tp->snd_max - tp->snd_una)) > 0) { u_int32_t incr = (tp->t_maxseg * tp->t_dupacks); /* Use Limited Transmit algorithm on the first two * duplicate acks when there is new data to transmit */ tp->snd_cwnd += incr; tcpstat.tcps_limited_txt++; (void) tcp_output(tp); tcp_ccdbg_trace(tp, th, TCP_CC_LIMITED_TRANSMIT); /* Reset snd_cwnd back to normal */ tp->snd_cwnd -= incr; } } break; } /* * If the congestion window was inflated to account * for the other side's cached packets, retract it. */ if (IN_FASTRECOVERY(tp)) { if (SEQ_LT(th->th_ack, tp->snd_recover)) { /* * If we received an ECE and entered * recovery, the subsequent ACKs should * not be treated as partial acks. */ if (tp->ecn_flags & TE_INRECOVERY) { goto process_ACK; } if (SACK_ENABLED(tp)) { tcp_sack_partialack(tp, th); } else { tcp_newreno_partial_ack(tp, th); } tcp_ccdbg_trace(tp, th, TCP_CC_PARTIAL_ACK); } else { if (tcp_cubic_minor_fixes) { exiting_fr = 1; } EXIT_FASTRECOVERY(tp); if (CC_ALGO(tp)->post_fr != NULL) { CC_ALGO(tp)->post_fr(tp, th); } tp->t_pipeack = 0; tcp_clear_pipeack_state(tp); tcp_ccdbg_trace(tp, th, TCP_CC_EXIT_FASTRECOVERY); } } else if ((tp->t_flagsext & (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) == (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) { /* * If the ack acknowledges upto snd_recover or if * it acknowledges all the snd holes, exit * recovery and cancel the timer. Otherwise, * this is a partial ack. Wait for recovery timer * to enter recovery. The snd_holes have already * been updated. */ if (SEQ_GEQ(th->th_ack, tp->snd_recover) || TAILQ_EMPTY(&tp->snd_holes)) { tp->t_timer[TCPT_DELAYFR] = 0; tp->t_flagsext &= ~TF_DELAY_RECOVERY; EXIT_FASTRECOVERY(tp); tcp_ccdbg_trace(tp, th, TCP_CC_EXIT_FASTRECOVERY); } } else { /* * We were not in fast recovery. Reset the * duplicate ack counter. */ tp->t_dupacks = 0; tp->t_rexmtthresh = tcprexmtthresh; tp->t_new_dupacks = 0; } process_ACK: VERIFY(SEQ_GEQ(th->th_ack, tp->snd_una)); acked = BYTES_ACKED(th, tp); tcpstat.tcps_rcvackpack++; tcpstat.tcps_rcvackbyte += acked; /* * If the last packet was a retransmit, make sure * it was not spurious. * * This will also take care of congestion window * adjustment if a last packet was recovered due to a * tail loss probe. */ tcp_bad_rexmt_check(tp, th, &to); /* Recalculate the RTT */ tcp_compute_rtt(tp, &to, th); /* * If all outstanding data is acked, stop retransmit * timer and remember to restart (more output or persist). * If there is more data to be acked, restart retransmit * timer, using current (possibly backed-off) value. */ TCP_RESET_REXMT_STATE(tp); TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), tp->t_rttmin, TCPTV_REXMTMAX, TCP_ADD_REXMTSLOP(tp)); if (th->th_ack == tp->snd_max) { tp->t_timer[TCPT_REXMT] = 0; tp->t_timer[TCPT_PTO] = 0; needoutput = 1; } else if (tp->t_timer[TCPT_PERSIST] == 0) { tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur); } if ((prev_t_state == TCPS_SYN_SENT || prev_t_state == TCPS_SYN_RECEIVED) && tp->t_state == TCPS_ESTABLISHED) { TCP_LOG_RTT_INFO(tp); } /* * If no data (only SYN) was ACK'd, skip rest of ACK * processing. */ if (acked == 0) { goto step6; } /* * When outgoing data has been acked (except the SYN+data), we * mark this connection as "sending good" for TFO. */ if ((tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) && !(tp->t_tfo_flags & TFO_F_NO_SNDPROBING) && !(th->th_flags & TH_SYN)) { tp->t_tfo_flags |= TFO_F_NO_SNDPROBING; } /* * Accurate ECN uses delta_cep to determine a congestion * event if new CE counts were received. * For classic ECN, congestion event is receiving TH_ECE. */ if ((tp->ecn_flags & TE_SENDIPECT)) { if (TCP_ACC_ECN_ON(tp)) { if (!IN_FASTRECOVERY(tp) && tp->t_delta_ce_packets > 0) { tcp_reduce_congestion_window(tp); tp->ecn_flags |= (TE_INRECOVERY); /* update the stats */ tcpstat.tcps_ecn_ace_recv_ce += tp->t_delta_ce_packets; tp->t_ecn_capable_packets_marked += tp->t_delta_ce_packets; tcp_ccdbg_trace(tp, th, TCP_CC_ECN_RCVD); } } else if (TCP_ECN_ENABLED(tp) && (thflags & TH_ECE)) { /* * Reduce the congestion window if we haven't * done so. */ if (!IN_FASTRECOVERY(tp)) { tcp_reduce_congestion_window(tp); tp->ecn_flags |= (TE_INRECOVERY | TE_SENDCWR); /* * Also note that the connection received * ECE atleast once. We increment * t_ecn_capable_packets_marked when we first * enter fast recovery. */ tp->ecn_flags |= TE_RECV_ECN_ECE; INP_INC_IFNET_STAT(inp, ecn_recv_ece); tcpstat.tcps_ecn_recv_ece++; tp->t_ecn_capable_packets_marked++; tcp_ccdbg_trace(tp, th, TCP_CC_ECN_RCVD); } } } /* * When new data is acked, open the congestion window. * The specifics of how this is achieved are up to the * congestion control algorithm in use for this connection. * * The calculations in this function assume that snd_una is * not updated yet. */ if (!IN_FASTRECOVERY(tp) && !exiting_fr) { if (CC_ALGO(tp)->ack_rcvd != NULL) { CC_ALGO(tp)->ack_rcvd(tp, th); } tcp_ccdbg_trace(tp, th, TCP_CC_ACK_RCVD); } if (acked > so->so_snd.sb_cc) { tp->snd_wnd -= so->so_snd.sb_cc; sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); ourfinisacked = 1; } else { sbdrop(&so->so_snd, acked); tcp_sbsnd_trim(&so->so_snd); tp->snd_wnd -= acked; ourfinisacked = 0; } /* detect una wraparound */ if (!IN_FASTRECOVERY(tp) && SEQ_GT(tp->snd_una, tp->snd_recover) && SEQ_LEQ(th->th_ack, tp->snd_recover)) { tp->snd_recover = th->th_ack - 1; } if (IN_FASTRECOVERY(tp) && SEQ_GEQ(th->th_ack, tp->snd_recover)) { EXIT_FASTRECOVERY(tp); } tcp_update_snd_una(tp, th->th_ack); if (SACK_ENABLED(tp)) { if (SEQ_GT(tp->snd_una, tp->snd_recover)) { tp->snd_recover = tp->snd_una; } } if (SEQ_LT(tp->snd_nxt, tp->snd_una)) { tp->snd_nxt = tp->snd_una; } if (!SLIST_EMPTY(&tp->t_rxt_segments) && !TCP_DSACK_SEQ_IN_WINDOW(tp, tp->t_dsack_lastuna, tp->snd_una)) { tcp_rxtseg_clean(tp); } if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 && tp->t_bwmeas != NULL) { tcp_bwmeas_check(tp); } write_wakeup = 1; if (!SLIST_EMPTY(&tp->t_notify_ack)) { tcp_notify_acknowledgement(tp, so); } switch (tp->t_state) { /* * In FIN_WAIT_1 STATE in addition to the processing * for the ESTABLISHED state if our FIN is now acknowledged * then enter FIN_WAIT_2. */ case TCPS_FIN_WAIT_1: if (ourfinisacked) { /* * If we can't receive any more * data, then closing user can proceed. * Starting the TCPT_2MSL timer is contrary to the * specification, but if we don't get a FIN * we'll hang forever. */ DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_2); TCP_LOG_STATE(tp, TCPS_FIN_WAIT_2); tp->t_state = TCPS_FIN_WAIT_2; if (so->so_state & SS_CANTRCVMORE) { isconnected = FALSE; isdisconnected = TRUE; tcp_set_finwait_timeout(tp); } /* * fall through and make sure we also recognize * data ACKed with the FIN */ } break; /* * In CLOSING STATE in addition to the processing for * the ESTABLISHED state if the ACK acknowledges our FIN * then enter the TIME-WAIT state, otherwise ignore * the segment. */ case TCPS_CLOSING: if (ourfinisacked) { DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_TIME_WAIT); TCP_LOG_STATE(tp, TCPS_TIME_WAIT); tp->t_state = TCPS_TIME_WAIT; tcp_canceltimers(tp); if (tp->t_flagsext & TF_NOTIMEWAIT) { tp->t_flags |= TF_CLOSING; } else { add_to_time_wait(tp, 2 * tcp_msl); } isconnected = FALSE; isdisconnected = TRUE; } break; /* * In LAST_ACK, we may still be waiting for data to drain * and/or to be acked, as well as for the ack of our FIN. * If our FIN is now acknowledged, delete the TCB, * enter the closed state and return. */ case TCPS_LAST_ACK: if (ourfinisacked) { tp = tcp_close(tp); goto drop; } break; /* * In TIME_WAIT state the only thing that should arrive * is a retransmission of the remote FIN. Acknowledge * it and restart the finack timer. */ case TCPS_TIME_WAIT: add_to_time_wait(tp, 2 * tcp_msl); goto dropafterack; } /* * If there is a SACK option on the ACK and we * haven't seen any duplicate acks before, count * it as a duplicate ack even if the cumulative * ack is advanced. If the receiver delayed an * ack and detected loss afterwards, then the ack * will advance cumulative ack and will also have * a SACK option. So counting it as one duplicate * ack is ok. */ if (tp->t_state == TCPS_ESTABLISHED && SACK_ENABLED(tp) && sack_bytes_acked > 0 && to.to_nsacks > 0 && tp->t_dupacks == 0 && SEQ_LEQ(th->th_ack, tp->snd_una) && tlen == 0 && !(tp->t_flagsext & TF_PKTS_REORDERED)) { tcpstat.tcps_sack_ackadv++; goto process_dupack; } } step6: /* * Update window information. */ if (tcp_update_window(tp, thflags, th, tiwin, tlen)) { needoutput = 1; } /* * Process segments with URG. */ if ((thflags & TH_URG) && th->th_urp && TCPS_HAVERCVDFIN(tp->t_state) == 0) { /* * This is a kludge, but if we receive and accept * random urgent pointers, we'll crash in * soreceive. It's hard to imagine someone * actually wanting to send this much urgent data. */ if (th->th_urp + so->so_rcv.sb_cc > sb_max) { th->th_urp = 0; /* XXX */ thflags &= ~TH_URG; /* XXX */ goto dodata; /* XXX */ } /* * If this segment advances the known urgent pointer, * then mark the data stream. This should not happen * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since * a FIN has been received from the remote side. * In these states we ignore the URG. * * According to RFC961 (Assigned Protocols), * the urgent pointer points to the last octet * of urgent data. We continue, however, * to consider it to indicate the first octet * of data past the urgent section as the original * spec states (in one of two places). */ if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) { tp->rcv_up = th->th_seq + th->th_urp; so->so_oobmark = so->so_rcv.sb_cc + (tp->rcv_up - tp->rcv_nxt) - 1; if (so->so_oobmark == 0) { so->so_state |= SS_RCVATMARK; } sohasoutofband(so); tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); } /* * Remove out of band data so doesn't get presented to user. * This can happen independent of advancing the URG pointer, * but if two URG's are pending at once, some out-of-band * data may creep in... ick. */ if (th->th_urp <= (u_int32_t)tlen #if SO_OOBINLINE && (so->so_options & SO_OOBINLINE) == 0 #endif ) { tcp_pulloutofband(so, th, m, drop_hdrlen); /* hdr drop is delayed */ } } else { /* * If no out of band data is expected, * pull receive urgent pointer along * with the receive window. */ if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) { tp->rcv_up = tp->rcv_nxt; } } dodata: /* Set socket's connect or disconnect state correcly before doing data. * The following might unlock the socket if there is an upcall or a socket * filter. */ if (isconnected) { soisconnected(so); } else if (isdisconnected) { soisdisconnected(so); } /* Let's check the state of pcb just to make sure that it did not get closed * when we unlocked above */ if (inp->inp_state == INPCB_STATE_DEAD) { /* Just drop the packet that we are processing and return */ TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "INPCB_STATE_DEAD"); goto drop; } /* * Process the segment text, merging it into the TCP sequencing queue, * and arranging for acknowledgment of receipt if necessary. * This process logically involves adjusting tp->rcv_wnd as data * is presented to the user (this happens in tcp_usrreq.c, * case PRU_RCVD). If a FIN has already been received on this * connection then we just ignore the text. * * If we are in SYN-received state and got a valid TFO cookie, we want * to process the data. */ if ((tlen || (thflags & TH_FIN)) && TCPS_HAVERCVDFIN(tp->t_state) == 0 && (TCPS_HAVEESTABLISHED(tp->t_state) || (tp->t_state == TCPS_SYN_RECEIVED && (tp->t_tfo_flags & TFO_F_COOKIE_VALID)))) { tcp_seq save_start = th->th_seq; tcp_seq save_end = th->th_seq + tlen; m_adj(m, drop_hdrlen); /* delayed header drop */ /* * Insert segment which includes th into TCP reassembly queue * with control block tp. Set thflags to whether reassembly now * includes a segment with FIN. This handles the common case * inline (segment is the next to be received on an established * connection, and the queue is empty), avoiding linkage into * and removal from the queue and repetition of various * conversions. * Set DELACK for segments received in order, but ack * immediately when segments are out of order (so * fast retransmit can work). */ if (th->th_seq == tp->rcv_nxt && LIST_EMPTY(&tp->t_segq)) { TCP_INC_VAR(tp->t_unacksegs, segment_count); /* Calculate the RTT on the receiver */ tcp_compute_rcv_rtt(tp, &to, th); if (DELAY_ACK(tp, th) && ((tp->t_flags & TF_ACKNOW) == 0)) { if ((tp->t_flags & TF_DELACK) == 0) { tp->t_flags |= TF_DELACK; tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack); } } else { tp->t_flags |= TF_ACKNOW; } tp->rcv_nxt += tlen; /* Update highest received sequence and its timestamp */ if (SEQ_LT(tp->rcv_high, tp->rcv_nxt)) { tp->rcv_high = tp->rcv_nxt; if (to.to_flags & TOF_TS) { tp->tsv_high = to.to_tsval; } } thflags = th->th_flags & TH_FIN; TCP_INC_VAR(tcpstat.tcps_rcvpack, segment_count); tcpstat.tcps_rcvbyte += tlen; if (nstat_collect) { INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, tlen); inp_set_activity_bitmap(inp); } tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen); if (TCP_USE_RLEDBAT(tp, so) && tcp_cc_rledbat.data_rcvd != NULL) { tcp_cc_rledbat.data_rcvd(tp, th, &to, tlen); } so_recv_data_stat(so, m, drop_hdrlen); if (isipv6) { memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); ip6 = (struct ip6_hdr *)&saved_hdr[0]; } else { memcpy(&saved_hdr, ip, ip->ip_hl << 2); ip = (struct ip *)&saved_hdr[0]; } memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); if (th->th_flags & TH_PUSH) { tp->t_flagsext |= TF_LAST_IS_PSH; } else { tp->t_flagsext &= ~TF_LAST_IS_PSH; } if (sbappendstream_rcvdemux(so, m)) { read_wakeup = 1; } th = &saved_tcphdr; } else { if (isipv6) { memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); ip6 = (struct ip6_hdr *)&saved_hdr[0]; } else { memcpy(&saved_hdr, ip, ip->ip_hl << 2); ip = (struct ip *)&saved_hdr[0]; } /* Update highest received sequence and its timestamp */ if (SEQ_LT(tp->rcv_high, th->th_seq + tlen)) { tp->rcv_high = th->th_seq + tlen; if (to.to_flags & TOF_TS) { tp->tsv_high = to.to_tsval; } } /* * Calculate the RTT on the receiver, * even if OOO segment is received. */ tcp_compute_rcv_rtt(tp, &to, th); if (tcp_autotune_reorder) { tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen); } if (TCP_USE_RLEDBAT(tp, so) && tcp_cc_rledbat.data_rcvd != NULL) { tcp_cc_rledbat.data_rcvd(tp, th, &to, tlen); } memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); thflags = tcp_reass(tp, th, &tlen, m, ifp, &read_wakeup); th = &saved_tcphdr; tp->t_flags |= TF_ACKNOW; } if ((tlen > 0 || (th->th_flags & TH_FIN)) && SACK_ENABLED(tp)) { if (th->th_flags & TH_FIN) { save_end++; } tcp_update_sack_list(tp, save_start, save_end); } tcp_adaptive_rwtimo_check(tp, tlen); if (tlen > 0) { tcp_tfo_rcv_data(tp); } if (tp->t_flags & TF_DELACK) { if (isipv6) { KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])), th->th_seq, th->th_ack, th->th_win); } else { KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), th->th_seq, th->th_ack, th->th_win); } } } else { if ((so->so_flags & SOF_MP_SUBFLOW) && tlen == 0 && (m->m_pkthdr.pkt_flags & PKTF_MPTCP_DFIN) && (m->m_pkthdr.pkt_flags & PKTF_MPTCP)) { m_adj(m, drop_hdrlen); /* delayed header drop */ /* * 0-length DATA_FIN. The rlen is actually 0. We special-case the * byte consumed by the dfin in mptcp_input and mptcp_reass_present */ m->m_pkthdr.mp_rlen = 0; mptcp_input(tptomptp(tp)->mpt_mpte, m); tp->t_flags |= TF_ACKNOW; } else { m_freem(m); } thflags &= ~TH_FIN; } /* * We increment t_unacksegs_ce for both data segments and pure ACKs * No need to increment if a FIN has already been received. */ if (TCP_ACC_ECN_ON(tp) && TCPS_HAVEESTABLISHED(tp->t_state) && TCPS_HAVERCVDFIN(tp->t_state) == 0) { if (ip_ecn == IPTOS_ECN_CE) { TCP_INC_VAR(tp->t_unacksegs_ce, segment_count); } /* * Send an ACK immediately if there is a change in IP ECN * from non-CE to CE. * If new data is delivered, then ACK for every 2 CE marks, * otherwise ACK for every 3 CE marks */ if ((ip_ecn == IPTOS_ECN_CE && ip_ecn != tp->t_prev_ip_ecn) || (tp->t_unacksegs_ce >= 2 && tp->last_ack_sent != tp->rcv_nxt) || tp->t_unacksegs_ce >= 3) { tp->t_flags |= TF_ACKNOW; } tp->t_prev_ip_ecn = ip_ecn; } /* * If FIN is received ACK the FIN and let the user know * that the connection is closing. */ if (thflags & TH_FIN) { if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { socantrcvmore(so); /* * If connection is half-synchronized * (ie NEEDSYN flag on) then delay ACK, * so it may be piggybacked when SYN is sent. * Otherwise, since we received a FIN then no * more input can be expected, send ACK now. */ TCP_INC_VAR(tp->t_unacksegs, segment_count); tp->t_flags |= TF_ACKNOW; tp->rcv_nxt++; } switch (tp->t_state) { /* * In SYN_RECEIVED and ESTABLISHED STATES * enter the CLOSE_WAIT state. */ case TCPS_SYN_RECEIVED: tp->t_starttime = tcp_now; OS_FALLTHROUGH; case TCPS_ESTABLISHED: DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_CLOSE_WAIT); TCP_LOG_STATE(tp, TCPS_CLOSE_WAIT); tp->t_state = TCPS_CLOSE_WAIT; break; /* * If still in FIN_WAIT_1 STATE FIN has not been acked so * enter the CLOSING state. */ case TCPS_FIN_WAIT_1: DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_CLOSING); TCP_LOG_STATE(tp, TCPS_CLOSING); tp->t_state = TCPS_CLOSING; break; /* * In FIN_WAIT_2 state enter the TIME_WAIT state, * starting the time-wait timer, turning off the other * standard timers. */ case TCPS_FIN_WAIT_2: DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, struct tcpcb *, tp, int32_t, TCPS_TIME_WAIT); TCP_LOG_STATE(tp, TCPS_TIME_WAIT); tp->t_state = TCPS_TIME_WAIT; tcp_canceltimers(tp); tp->t_flags |= TF_ACKNOW; if (tp->t_flagsext & TF_NOTIMEWAIT) { tp->t_flags |= TF_CLOSING; } else { add_to_time_wait(tp, 2 * tcp_msl); } soisdisconnected(so); break; /* * In TIME_WAIT state restart the 2 MSL time_wait timer. */ case TCPS_TIME_WAIT: add_to_time_wait(tp, 2 * tcp_msl); break; } } #if TCPDEBUG if (so->so_options & SO_DEBUG) { tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, &tcp_savetcp, 0); } #endif if (read_wakeup) { mptcp_handle_input(so); } /* * Return any desired output. */ if (needoutput || (tp->t_flags & TF_ACKNOW)) { (void) tcp_output(tp); } tcp_check_timer_state(tp); tcp_handle_wakeup(so, read_wakeup, write_wakeup); socket_unlock(so, 1); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); return; dropafterack: /* * Generate an ACK dropping incoming segment if it occupies * sequence space, where the ACK reflects our state. * * We can now skip the test for the RST flag since all * paths to this code happen after packets containing * RST have been dropped. * * In the SYN-RECEIVED state, don't send an ACK unless the * segment we received passes the SYN-RECEIVED ACK test. * If it fails send a RST. This breaks the loop in the * "LAND" DoS attack, and also prevents an ACK storm * between two listening ports that have been sent forged * SYN segments, each with the source address of the other. */ if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && (SEQ_GT(tp->snd_una, th->th_ack) || SEQ_GT(th->th_ack, tp->snd_max))) { IF_TCP_STATINC(ifp, dospacket); goto dropwithreset; } #if TCPDEBUG if (so->so_options & SO_DEBUG) { tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, &tcp_savetcp, 0); } #endif m_freem(m); tp->t_flags |= TF_ACKNOW; (void) tcp_output(tp); tcp_handle_wakeup(so, read_wakeup, write_wakeup); /* Don't need to check timer state as we should have done it during tcp_output */ socket_unlock(so, 1); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); return; dropwithresetnosock: nosock = 1; dropwithreset: /* * Generate a RST, dropping incoming segment. * Make ACK acceptable to originator of segment. * Don't bother to respond if destination was broadcast/multicast. */ if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST)) { goto drop; } if (isipv6) { if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { goto drop; } } else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { goto drop; } /* IPv6 anycast check is done at tcp6_input() */ #if TCPDEBUG if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) { tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, &tcp_savetcp, 0); } #endif bzero(&tra, sizeof(tra)); tra.ifscope = ifscope; tra.awdl_unrestricted = 1; tra.intcoproc_allowed = 1; tra.management_allowed = 1; if (thflags & TH_ACK) { /* mtod() below is safe as long as hdr dropping is delayed */ tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack, TH_RST, &tra); } else { if (thflags & TH_SYN) { tlen++; } /* mtod() below is safe as long as hdr dropping is delayed */ tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen, (tcp_seq)0, TH_RST | TH_ACK, &tra); } /* destroy temporarily created socket */ if (dropsocket) { (void) soabort(so); socket_unlock(so, 1); } else if ((inp != NULL) && (nosock == 0)) { tcp_handle_wakeup(so, read_wakeup, write_wakeup); socket_unlock(so, 1); } KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); return; dropnosock: nosock = 1; drop: /* * Drop space held by incoming segment and return. */ #if TCPDEBUG if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) { tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, &tcp_savetcp, 0); } #endif m_freem(m); /* destroy temporarily created socket */ if (dropsocket) { (void) soabort(so); socket_unlock(so, 1); } else if (nosock == 0) { tcp_handle_wakeup(so, read_wakeup, write_wakeup); socket_unlock(so, 1); } KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); return; } /* * Parse TCP options and place in tcpopt. */ static void tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcphdr *th, struct tcpopt *to) { u_short mss = 0; uint8_t opt, optlen; for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[0]; if (opt == TCPOPT_EOL) { break; } if (opt == TCPOPT_NOP) { optlen = 1; } else { if (cnt < 2) { break; } optlen = cp[1]; if (optlen < 2 || optlen > cnt) { break; } } switch (opt) { default: continue; case TCPOPT_MAXSEG: if (optlen != TCPOLEN_MAXSEG) { continue; } if (!(th->th_flags & TH_SYN)) { continue; } bcopy((char *) cp + 2, (char *) &mss, sizeof(mss)); NTOHS(mss); to->to_mss = mss; to->to_flags |= TOF_MSS; break; case TCPOPT_WINDOW: if (optlen != TCPOLEN_WINDOW) { continue; } if (!(th->th_flags & TH_SYN)) { continue; } to->to_flags |= TOF_SCALE; to->to_requested_s_scale = MIN(cp[2], TCP_MAX_WINSHIFT); break; case TCPOPT_TIMESTAMP: if (optlen != TCPOLEN_TIMESTAMP) { continue; } to->to_flags |= TOF_TS; bcopy((char *)cp + 2, (char *)&to->to_tsval, sizeof(to->to_tsval)); NTOHL(to->to_tsval); bcopy((char *)cp + 6, (char *)&to->to_tsecr, sizeof(to->to_tsecr)); NTOHL(to->to_tsecr); to->to_tsecr -= tp->t_ts_offset; /* Re-enable sending Timestamps if we received them */ if (!(tp->t_flags & TF_REQ_TSTMP) && tcp_do_timestamps) { tp->t_flags |= TF_REQ_TSTMP; } break; case TCPOPT_SACK_PERMITTED: if (optlen != TCPOLEN_SACK_PERMITTED) { continue; } if (th->th_flags & TH_SYN) { to->to_flags |= TOF_SACK; } break; case TCPOPT_SACK: if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) { continue; } to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; to->to_sacks = cp + 2; tcpstat.tcps_sack_rcv_blocks++; break; case TCPOPT_FASTOPEN: if (optlen == TCPOLEN_FASTOPEN_REQ) { if (tp->t_state != TCPS_LISTEN) { continue; } to->to_flags |= TOF_TFOREQ; } else { if (optlen < TCPOLEN_FASTOPEN_REQ || (optlen - TCPOLEN_FASTOPEN_REQ) > TFO_COOKIE_LEN_MAX || (optlen - TCPOLEN_FASTOPEN_REQ) < TFO_COOKIE_LEN_MIN) { continue; } if (tp->t_state != TCPS_LISTEN && tp->t_state != TCPS_SYN_SENT) { continue; } to->to_flags |= TOF_TFO; to->to_tfo = cp + 1; } break; #if MPTCP case TCPOPT_MULTIPATH: tcp_do_mptcp_options(tp, cp, th, to, optlen); break; #endif /* MPTCP */ } } } static void tcp_finalize_options(struct tcpcb *tp, struct tcpopt *to, unsigned int ifscope) { if (to->to_flags & TOF_TS) { tp->t_flags |= TF_RCVD_TSTMP; tp->ts_recent = to->to_tsval; tp->ts_recent_age = tcp_now; } if (to->to_flags & TOF_MSS) { tcp_mss(tp, to->to_mss, ifscope); } if (SACK_ENABLED(tp)) { if (!(to->to_flags & TOF_SACK)) { tp->t_flagsext &= ~(TF_SACK_ENABLE); } else { tp->t_flags |= TF_SACK_PERMIT; } } if (to->to_flags & TOF_SCALE) { tp->t_flags |= TF_RCVD_SCALE; tp->requested_s_scale = to->to_requested_s_scale; /* Re-enable window scaling, if the option is received */ if (tp->request_r_scale > 0) { tp->t_flags |= TF_REQ_SCALE; } } } /* * Pull out of band byte out of a segment so * it doesn't appear in the user's data queue. * It is still reflected in the segment length for * sequencing purposes. * * @param off delayed to be droped hdrlen */ static void tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off) { int cnt = off + th->th_urp - 1; while (cnt >= 0) { if (m->m_len > cnt) { char *cp = mtod(m, caddr_t) + cnt; struct tcpcb *tp = sototcpcb(so); tp->t_iobc = *cp; tp->t_oobflags |= TCPOOB_HAVEDATA; bcopy(cp + 1, cp, (unsigned)(m->m_len - cnt - 1)); m->m_len--; if (m->m_flags & M_PKTHDR) { m->m_pkthdr.len--; } return; } cnt -= m->m_len; m = m->m_next; if (m == 0) { break; } } panic("tcp_pulloutofband"); } uint32_t get_base_rtt(struct tcpcb *tp) { struct rtentry *rt = tp->t_inpcb->inp_route.ro_rt; return (rt == NULL) ? 0 : rt->rtt_min; } static void update_curr_rtt(struct tcpcb * tp, uint32_t rtt) { tp->curr_rtt_index = (tp->curr_rtt_index + 1) % NCURR_RTT_HIST; tp->curr_rtt_hist[tp->curr_rtt_index] = rtt; /* forget the old value and update minimum */ tp->curr_rtt_min = 0; for (int i = 0; i < NCURR_RTT_HIST; ++i) { if (tp->curr_rtt_hist[i] != 0 && (tp->curr_rtt_min == 0 || tp->curr_rtt_hist[i] < tp->curr_rtt_min)) { tp->curr_rtt_min = tp->curr_rtt_hist[i]; } } } /* Each value of RTT base represents the minimum RTT seen in a minute. * We keep upto N_RTT_BASE minutes worth of history. */ void update_base_rtt(struct tcpcb *tp, uint32_t rtt) { u_int32_t base_rtt, i; struct rtentry *rt; if ((rt = tp->t_inpcb->inp_route.ro_rt) == NULL) { return; } if (rt->rtt_expire_ts == 0) { RT_LOCK_SPIN(rt); if (rt->rtt_expire_ts != 0) { RT_UNLOCK(rt); goto update; } rt->rtt_expire_ts = tcp_now; rt->rtt_index = 0; rt->rtt_hist[0] = rtt; rt->rtt_min = rtt; RT_UNLOCK(rt); tp->curr_rtt_index = 0; tp->curr_rtt_hist[0] = rtt; tp->curr_rtt_min = rtt; return; } update: #if TRAFFIC_MGT /* * If the recv side is being throttled, check if the * current RTT is closer to the base RTT seen in * first (recent) two slots. If so, unthrottle the stream. */ if ((tp->t_flagsext & TF_RECV_THROTTLE) && (int)(tcp_now - tp->t_recv_throttle_ts) >= TCP_RECV_THROTTLE_WIN) { base_rtt = rt->rtt_min; if (tp->t_rttcur <= (base_rtt + target_qdelay)) { tp->t_flagsext &= ~TF_RECV_THROTTLE; tp->t_recv_throttle_ts = 0; } } #endif /* TRAFFIC_MGT */ /* Update the next current RTT sample */ update_curr_rtt(tp, rtt); if ((int)(tcp_now - rt->rtt_expire_ts) >= TCP_RTT_HISTORY_EXPIRE_TIME) { RT_LOCK_SPIN(rt); /* check the condition again to avoid race */ if ((int)(tcp_now - rt->rtt_expire_ts) >= TCP_RTT_HISTORY_EXPIRE_TIME) { /* Set the base rtt to 0 for idle periods */ uint32_t times = MIN((tcp_now - rt->rtt_expire_ts) / TCP_RTT_HISTORY_EXPIRE_TIME, NRTT_HIST + 1); for (i = rt->rtt_index + 1; i < rt->rtt_index + times; i++) { rt->rtt_hist[i % NRTT_HIST] = 0; } rt->rtt_index = i % NRTT_HIST; rt->rtt_hist[rt->rtt_index] = rtt; rt->rtt_expire_ts = tcp_now; } else { rt->rtt_hist[rt->rtt_index] = min(rt->rtt_hist[rt->rtt_index], rtt); } /* forget the old value and update minimum */ rt->rtt_min = 0; for (i = 0; i < NRTT_HIST; ++i) { if (rt->rtt_hist[i] != 0 && (rt->rtt_min == 0 || rt->rtt_hist[i] < rt->rtt_min)) { rt->rtt_min = rt->rtt_hist[i]; } } RT_UNLOCK(rt); } else { rt->rtt_hist[rt->rtt_index] = min(rt->rtt_hist[rt->rtt_index], rtt); if (rt->rtt_min == 0) { rt->rtt_min = rtt; } else { rt->rtt_min = min(rt->rtt_min, rtt); } } } /* * If we have a timestamp reply, update smoothed RTT. If no timestamp is * present but transmit timer is running and timed sequence number was * acked, update smoothed RTT. * * If timestamps are supported, a receiver can update RTT even if * there is no outstanding data. * * Some boxes send broken timestamp replies during the SYN+ACK phase, * ignore timestamps of 0or we could calculate a huge RTT and blow up * the retransmit timer. */ static void tcp_compute_rtt(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th) { int rtt = 0; VERIFY(to != NULL && th != NULL); if (tp->t_rtttime != 0 && SEQ_GT(th->th_ack, tp->t_rtseq)) { u_int32_t pipe_ack_val; rtt = tcp_now - tp->t_rtttime; if (rtt == 0) { /* * Make adjustment for sub ms RTT when * timestamps are not used. */ rtt = 1; } /* * Compute pipe ack -- the amount of data acknowledged * in the last RTT -- only works for sender */ if (SEQ_GT(th->th_ack, tp->t_pipeack_lastuna)) { pipe_ack_val = th->th_ack - tp->t_pipeack_lastuna; /* Update the sample */ tp->t_pipeack_sample[tp->t_pipeack_ind++] = pipe_ack_val; tp->t_pipeack_ind %= TCP_PIPEACK_SAMPLE_COUNT; /* Compute the max of the pipeack samples */ pipe_ack_val = tcp_get_max_pipeack(tp); tp->t_pipeack = (pipe_ack_val > tcp_initial_cwnd(tp)) ? pipe_ack_val : 0; } /* start another measurement */ tp->t_rtttime = 0; } if (((to->to_flags & TOF_TS) != 0) && (to->to_tsecr != 0) && TSTMP_GEQ(tcp_now, to->to_tsecr)) { tcp_xmit_timer(tp, (tcp_now - to->to_tsecr), to->to_tsecr, th->th_ack); } else if (rtt > 0) { tcp_xmit_timer(tp, rtt, 0, th->th_ack); } } static void tcp_compute_rcv_rtt(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th) { uint32_t rtt = 0, delta = 0; VERIFY(to != NULL && th != NULL); /* Calculate RTT */ if (((to->to_flags & TOF_TS) != 0) && (to->to_tsecr != 0) && TSTMP_GEQ(tcp_now, to->to_tsecr)) { /* Timestamp is supported */ rtt = tcp_now - to->to_tsecr; if (rtt == 0) { /* Make adjustment for sub ms RTT */ rtt = 1; } } else if ((to->to_flags & TOF_TS) == 0) { /* * Timestamp is not supported, 1RTT is roughly * the time to receive one full window of data * Currently, RTT calculated this way is only used * for auto-tuning. */ if (tp->rcv_rtt_est_ts != 0) { if (SEQ_LT(tp->rcv_nxt, tp->rcv_rtt_est_seq)) { /* Haven't received a full window yet */ return; } else { rtt = tcp_now - tp->rcv_rtt_est_ts; if (rtt == 0) { /* Make adjustment for sub ms RTT */ rtt = 1; } } } else { /* Use default value when no RTT measurement */ rtt = TCPTV_RCVNOTS_QUANTUM; } /* Restart the measurement */ tp->rcv_rtt_est_ts = tcp_now; tp->rcv_rtt_est_seq = tp->rcv_nxt + tp->rcv_wnd; } /* Update receiver's SRTT */ if (tp->rcv_srtt != 0) { /* * Use the smoothed rtt formula, * (srtt = rtt/8 + srtt*7/8) in fixed point */ delta = (rtt << TCP_DELTA_SHIFT) - (tp->rcv_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); if ((tp->rcv_srtt += delta) <= 0) { tp->rcv_srtt = 1; } } else { /* No previous measurement */ tp->rcv_srtt = rtt << TCP_RTT_SHIFT; } /* * For current RTT, base RTT and current RTT over k samples, * we are using the same state for both sender and receiver * as the most recent sample is always updated before any * other processing, i.e. the sender will not end up with * a high RTT due to the receiver. */ tp->t_rttcur = rtt; update_base_rtt(tp, rtt); } /* * Collect new round-trip time estimate and update averages and * current timeout. */ static void tcp_xmit_timer(struct tcpcb *tp, int rtt, u_int32_t tsecr, tcp_seq th_ack) { VERIFY(rtt >= 0); int delta; int old_srtt = tp->t_srtt; int old_rttvar = tp->t_rttvar; bool log_rtt = false; if (rtt == 0) { /* * As rtt has millisecond precision, * make adjustment for sub ms RTT */ rtt = 1; } if (rtt > 4 * TCPTV_MSL) { TCP_LOG(tp, "%s: rtt is %d - maxing it at 4 x MSL\n", __func__, rtt); /* * We compute RTT either based on the time-to-ACK a packet, * if TSval is disabled or based on the TSecr value. * If there is a middlebox messing up the TSecr value, we can * end up having HUGE rtt values, causing all kinds of problems. * Let's protect against this by capping RTT to 4*MSL * (60seconds). */ rtt = 4 * TCPTV_MSL; } /* * On AWDL interface, the initial RTT measurement on SYN * can be wrong due to peer caching. Avoid the first RTT * measurement as it might skew up the RTO. * */ if (tp->t_inpcb->inp_last_outifp != NULL && (tp->t_inpcb->inp_last_outifp->if_eflags & IFEF_AWDL) && th_ack == tp->iss + 1) { return; } if (tp->t_flagsext & TF_RECOMPUTE_RTT) { if (SEQ_GT(th_ack, tp->snd_una) && SEQ_LEQ(th_ack, tp->snd_max) && (tsecr == 0 || TSTMP_GEQ(tsecr, tp->t_badrexmt_time))) { /* * We received a new ACK after a * spurious timeout. Adapt retransmission * timer as described in rfc 4015. */ tp->t_flagsext &= ~(TF_RECOMPUTE_RTT); tp->t_badrexmt_time = 0; tp->t_srtt = max(tp->t_srtt_prev, rtt); tp->t_srtt = tp->t_srtt << TCP_RTT_SHIFT; tp->t_rttvar = max(tp->t_rttvar_prev, (rtt >> 1)); tp->t_rttvar = tp->t_rttvar << TCP_RTTVAR_SHIFT; if (tp->t_rttbest > (tp->t_srtt + tp->t_rttvar)) { tp->t_rttbest = tp->t_srtt + tp->t_rttvar; } goto compute_rto; } else { return; } } tcpstat.tcps_rttupdated++; tp->t_rttupdated++; tp->t_rttcur = rtt; update_base_rtt(tp, rtt); if (tp->t_srtt != 0) { /* * srtt is stored as fixed point with 5 bits after the * binary point (i.e., scaled by 32). The following magic * is equivalent to the smoothing algorithm in rfc793 with * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed * point). * * Freebsd adjusts rtt to origin 0 by subtracting 1 * from the provided rtt value. This was required because * of the way t_rtttime was initiailised to 1 before. * Since we changed t_rtttime to be based on * tcp_now, this extra adjustment is not needed. */ delta = (rtt << TCP_DELTA_SHIFT) - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); if ((tp->t_srtt += delta) <= 0) { tp->t_srtt = 1; } /* * We accumulate a smoothed rtt variance (actually, a * smoothed mean difference), then set the retransmit * timer to smoothed rtt + 4 times the smoothed variance. * rttvar is stored as fixed point with 4 bits after the * binary point (scaled by 16). The following is * equivalent to rfc793 smoothing with an alpha of .75 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces * rfc793's wired-in beta. */ if (delta < 0) { delta = -delta; } delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); if ((tp->t_rttvar += delta) <= 0) { tp->t_rttvar = 1; } if (tp->t_rttbest == 0 || tp->t_rttbest > (tp->t_srtt + tp->t_rttvar)) { tp->t_rttbest = tp->t_srtt + tp->t_rttvar; } } else { /* * No rtt measurement yet - use the unsmoothed rtt. * Set the variance to half the rtt (so our first * retransmit happens at 3*rtt). */ tp->t_srtt = rtt << TCP_RTT_SHIFT; tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); tp->t_rttbest = tp->t_srtt + tp->t_rttvar; /* Initialize the receive SRTT */ if (tp->rcv_srtt == 0) { tp->rcv_srtt = tp->t_srtt; } } compute_rto: nstat_route_rtt(tp->t_inpcb->inp_route.ro_rt, tp->t_srtt, tp->t_rttvar); /* * the retransmit should happen at rtt + 4 * rttvar. * Because of the way we do the smoothing, srtt and rttvar * will each average +1/2 tick of bias. When we compute * the retransmit timer, we want 1/2 tick of rounding and * 1 extra tick because of +-1/2 tick uncertainty in the * firing of the timer. The bias will give us exactly the * 1.5 tick we need. But, because the bias is * statistical, we have to test that we don't drop below * the minimum feasible timer (which is 2 ticks). */ TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX, TCP_ADD_REXMTSLOP(tp)); /* * We received an ack for a packet that wasn't retransmitted; * it is probably safe to discard any error indications we've * received recently. This isn't quite right, but close enough * for now (a route might have failed after we sent a segment, * and the return path might not be symmetrical). */ tp->t_softerror = 0; if (log_rtt) { TCP_LOG_RTT_INFO(tp); } TCP_LOG_RTT_CHANGE(tp, old_srtt, old_rttvar); } static inline unsigned int tcp_maxmtu(struct rtentry *rt) { unsigned int maxmtu; int interface_mtu = 0; RT_LOCK_ASSERT_HELD(rt); interface_mtu = rt->rt_ifp->if_mtu; if (rt_key(rt)->sa_family == AF_INET && INTF_ADJUST_MTU_FOR_CLAT46(rt->rt_ifp)) { interface_mtu = IN6_LINKMTU(rt->rt_ifp); /* Further adjust the size for CLAT46 expansion */ interface_mtu -= CLAT46_HDR_EXPANSION_OVERHD; } if (rt->rt_rmx.rmx_mtu == 0) { maxmtu = interface_mtu; } else { maxmtu = MIN(rt->rt_rmx.rmx_mtu, interface_mtu); } return maxmtu; } static inline unsigned int tcp_maxmtu6(struct rtentry *rt) { unsigned int maxmtu; struct nd_ifinfo *ndi = NULL; RT_LOCK_ASSERT_HELD(rt); if ((ndi = ND_IFINFO(rt->rt_ifp)) != NULL && !ndi->initialized) { ndi = NULL; } if (ndi != NULL) { lck_mtx_lock(&ndi->lock); } if (rt->rt_rmx.rmx_mtu == 0) { maxmtu = IN6_LINKMTU(rt->rt_ifp); } else { maxmtu = MIN(rt->rt_rmx.rmx_mtu, IN6_LINKMTU(rt->rt_ifp)); } if (ndi != NULL) { lck_mtx_unlock(&ndi->lock); } return maxmtu; } unsigned int get_maxmtu(struct rtentry *rt) { unsigned int maxmtu = 0; RT_LOCK_ASSERT_NOTHELD(rt); RT_LOCK(rt); if (rt_key(rt)->sa_family == AF_INET6) { maxmtu = tcp_maxmtu6(rt); } else { maxmtu = tcp_maxmtu(rt); } RT_UNLOCK(rt); return maxmtu; } /* * Determine a reasonable value for maxseg size. * If the route is known, check route for mtu. * If none, use an mss that can be handled on the outgoing * interface without forcing IP to fragment; if bigger than * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES * to utilize large mbufs. If no route is found, route has no mtu, * or the destination isn't local, use a default, hopefully conservative * size (usually 512 or the default IP max size, but no more than the mtu * of the interface), as we can't discover anything about intervening * gateways or networks. We also initialize the congestion/slow start * window. While looking at the routing entry, we also initialize * other path-dependent parameters from pre-set or cached values * in the routing entry. * * Also take into account the space needed for options that we * send regularly. Make maxseg shorter by that amount to assure * that we can send maxseg amount of data even when the options * are present. Store the upper limit of the length of options plus * data in maxopd. * * NOTE that this routine is only called when we process an incoming * segment, for outgoing segments only tcp_mssopt is called. * */ void tcp_mss(struct tcpcb *tp, int offer, unsigned int input_ifscope) { struct rtentry *rt; struct ifnet *ifp; int rtt, mss; uint32_t bufsize; struct inpcb *inp; struct socket *so; int origoffer = offer; int isnetlocal = 0; int isipv6; int min_protoh; inp = tp->t_inpcb; so = inp->inp_socket; /* * Nothing left to send after the socket is defunct or TCP is in the closed state */ if ((so->so_state & SS_DEFUNCT) || tp->t_state == TCPS_CLOSED) { return; } isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; min_protoh = isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : sizeof(struct tcpiphdr); if (isipv6) { rt = tcp_rtlookup6(inp, input_ifscope); } else { rt = tcp_rtlookup(inp, input_ifscope); } isnetlocal = (tp->t_flags & TF_LOCAL); if (rt == NULL) { tp->t_maxopd = tp->t_maxseg = isipv6 ? tcp_v6mssdflt : tcp_mssdflt; return; } ifp = rt->rt_ifp; /* * Slower link window correction: * If a value is specificied for slowlink_wsize use it for * PPP links believed to be on a serial modem (speed <128Kbps). * Excludes 9600bps as it is the default value adversized * by pseudo-devices over ppp. */ if (ifp->if_type == IFT_PPP && slowlink_wsize > 0 && ifp->if_baudrate > 9600 && ifp->if_baudrate <= 128000) { tp->t_flags |= TF_SLOWLINK; } /* * Offer == -1 means that we didn't receive SYN yet. Use 0 then. */ if (offer == -1) { offer = rt->rt_rmx.rmx_filler[0]; } /* * Offer == 0 means that there was no MSS on the SYN segment, * in this case we use tcp_mssdflt. */ if (offer == 0) { offer = isipv6 ? tcp_v6mssdflt : tcp_mssdflt; } else { /* * Prevent DoS attack with too small MSS. Round up * to at least minmss. */ offer = max(offer, tcp_minmss); /* * Sanity check: make sure that maxopd will be large * enough to allow some data on segments even is the * all the option space is used (40bytes). Otherwise * funny things may happen in tcp_output. */ offer = max(offer, 64); } rt->rt_rmx.rmx_filler[0] = offer; /* * While we're here, check if there's an initial rtt * or rttvar. Convert from the route-table units * to scaled multiples of the slow timeout timer. */ if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt) != 0) { tcp_getrt_rtt(tp, rt); } else { tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCPTV_REXMTMIN; } mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt)); #if NECP // At this point, the mss is just the MTU. Adjust if necessary. mss = necp_socket_get_effective_mtu(inp, mss); #endif /* NECP */ mss -= min_protoh; if (rt->rt_rmx.rmx_mtu == 0) { if (isipv6) { if (!isnetlocal) { mss = min(mss, tcp_v6mssdflt); } } else if (!isnetlocal) { mss = min(mss, tcp_mssdflt); } } mss = min(mss, offer); /* * maxopd stores the maximum length of data AND options * in a segment; maxseg is the amount of data in a normal * segment. We need to store this value (maxopd) apart * from maxseg, because now every segment carries options * and thus we normally have somewhat less data in segments. */ tp->t_maxopd = mss; /* * origoffer==-1 indicates, that no segments were received yet. * In this case we just guess. */ if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP && (origoffer == -1 || (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) { mss -= TCPOLEN_TSTAMP_APPA; } #if MPTCP mss -= mptcp_adj_mss(tp, FALSE); #endif /* MPTCP */ tp->t_maxseg = mss; /* * If there's a pipesize (ie loopback), change the socket * buffer to that size only if it's bigger than the current * sockbuf size. Make the socket buffers an integral * number of mss units; if the mss is larger than * the socket buffer, decrease the mss. */ #if RTV_SPIPE bufsize = rt->rt_rmx.rmx_sendpipe; if (bufsize < so->so_snd.sb_hiwat) #endif bufsize = so->so_snd.sb_hiwat; if (bufsize < mss) { mss = bufsize; } else { bufsize = (((bufsize + mss - 1) / mss) * mss); (void)sbreserve(&so->so_snd, bufsize); } tp->t_maxseg = mss; ASSERT(tp->t_maxseg); /* * Update MSS using recommendation from link status report. This is * temporary */ tcp_update_mss_locked(so, ifp); #if RTV_RPIPE bufsize = rt->rt_rmx.rmx_recvpipe; if (bufsize < so->so_rcv.sb_hiwat) #endif bufsize = so->so_rcv.sb_hiwat; if (bufsize > mss) { bufsize = (((bufsize + mss - 1) / mss) * mss); (void)sbreserve(&so->so_rcv, bufsize); } set_tcp_stream_priority(so); if (rt->rt_rmx.rmx_ssthresh) { /* * There's some sort of gateway or interface * buffer limit on the path. Use this to set * slow-start threshold, but set the threshold to * no less than 2*mss. */ tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); tcpstat.tcps_usedssthresh++; } else { tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; } /* * Set the slow-start flight size depending on whether this * is a local network or not. */ if (CC_ALGO(tp)->cwnd_init != NULL) { CC_ALGO(tp)->cwnd_init(tp); } tcp_ccdbg_trace(tp, NULL, TCP_CC_CWND_INIT); if (TCP_USE_RLEDBAT(tp, so) && tcp_cc_rledbat.rwnd_init != NULL) { tcp_cc_rledbat.rwnd_init(tp); } /* Route locked during lookup above */ RT_UNLOCK(rt); } /* * Determine the MSS option to send on an outgoing SYN. */ int tcp_mssopt(struct tcpcb *tp) { struct rtentry *rt; int mss; int isipv6; int min_protoh; isipv6 = ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) ? 1 : 0; min_protoh = isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : sizeof(struct tcpiphdr); if (isipv6) { rt = tcp_rtlookup6(tp->t_inpcb, IFSCOPE_NONE); } else { rt = tcp_rtlookup(tp->t_inpcb, IFSCOPE_NONE); } if (rt == NULL) { return isipv6 ? tcp_v6mssdflt : tcp_mssdflt; } /* * Slower link window correction: * If a value is specificied for slowlink_wsize use it for PPP links * believed to be on a serial modem (speed <128Kbps). Excludes 9600bps as * it is the default value adversized by pseudo-devices over ppp. */ if (rt->rt_ifp->if_type == IFT_PPP && slowlink_wsize > 0 && rt->rt_ifp->if_baudrate > 9600 && rt->rt_ifp->if_baudrate <= 128000) { tp->t_flags |= TF_SLOWLINK; } mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt)); /* Route locked during lookup above */ RT_UNLOCK(rt); #if NECP // At this point, the mss is just the MTU. Adjust if necessary. mss = necp_socket_get_effective_mtu(tp->t_inpcb, mss); #endif /* NECP */ return mss - min_protoh; } /* * On a partial ack arrives, force the retransmission of the * next unacknowledged segment. Do not clear tp->t_dupacks. * By setting snd_nxt to th_ack, this forces retransmission timer to * be started again. */ static void tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) { tcp_seq onxt = tp->snd_nxt; u_int32_t ocwnd = tp->snd_cwnd; tp->t_timer[TCPT_REXMT] = 0; tp->t_timer[TCPT_PTO] = 0; tp->t_rtttime = 0; tp->snd_nxt = th->th_ack; /* * Set snd_cwnd to one segment beyond acknowledged offset * (tp->snd_una has not yet been updated when this function * is called) */ tp->snd_cwnd = tp->t_maxseg + BYTES_ACKED(th, tp); (void) tcp_output(tp); tp->snd_cwnd = ocwnd; if (SEQ_GT(onxt, tp->snd_nxt)) { tp->snd_nxt = onxt; } /* * Partial window deflation. Relies on fact that tp->snd_una * not updated yet. */ if (tp->snd_cwnd > BYTES_ACKED(th, tp)) { tp->snd_cwnd -= BYTES_ACKED(th, tp); } else { tp->snd_cwnd = 0; } tp->snd_cwnd += tp->t_maxseg; } /* * Drop a random TCP connection that hasn't been serviced yet and * is eligible for discard. There is a one in qlen chance that * we will return a null, saying that there are no dropable * requests. In this case, the protocol specific code should drop * the new request. This insures fairness. * * The listening TCP socket "head" must be locked */ static int tcp_dropdropablreq(struct socket *head) { struct socket *so, *sonext; unsigned int j, qlen; static uint32_t rnd = 0; static uint64_t old_runtime; static unsigned int cur_cnt, old_cnt; uint64_t now_sec, i; struct inpcb *inp = NULL; struct tcpcb *tp; if ((head->so_options & SO_ACCEPTCONN) == 0) { return 0; } if (TAILQ_EMPTY(&head->so_incomp)) { return 0; } so_acquire_accept_list(head, NULL); socket_unlock(head, 0); /* * Check if there is any socket in the incomp queue * that is closed because of a reset from the peer and is * waiting to be garbage collected. If so, pick that as * the victim */ TAILQ_FOREACH_SAFE(so, &head->so_incomp, so_list, sonext) { inp = sotoinpcb(so); tp = intotcpcb(inp); if (tp != NULL && tp->t_state == TCPS_CLOSED && so->so_head != NULL && (so->so_state & (SS_INCOMP | SS_CANTSENDMORE | SS_CANTRCVMORE)) == (SS_INCOMP | SS_CANTSENDMORE | SS_CANTRCVMORE)) { /* * The listen socket is already locked but we * can lock this socket here without lock ordering * issues because it is in the incomp queue and * is not visible to others. */ if (socket_try_lock(so)) { so->so_usecount++; goto found_victim; } else { continue; } } } so = TAILQ_FIRST(&head->so_incomp); now_sec = net_uptime(); if ((i = (now_sec - old_runtime)) != 0) { old_runtime = now_sec; old_cnt = cur_cnt / i; cur_cnt = 0; } qlen = head->so_incqlen; if (rnd == 0) { rnd = RandomULong(); } if (++cur_cnt > qlen || old_cnt > qlen) { rnd = (314159 * rnd + 66329) & 0xffff; j = ((qlen + 1) * rnd) >> 16; while (j-- && so) { so = TAILQ_NEXT(so, so_list); } } /* Find a connection that is not already closing (or being served) */ while (so) { inp = (struct inpcb *)so->so_pcb; sonext = TAILQ_NEXT(so, so_list); if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) != WNT_STOPUSING) { /* * Avoid the issue of a socket being accepted * by one input thread and being dropped by * another input thread. If we can't get a hold * on this mutex, then grab the next socket in * line. */ if (socket_try_lock(so)) { so->so_usecount++; if ((so->so_usecount == 2) && (so->so_state & SS_INCOMP) && !(so->so_flags & SOF_INCOMP_INPROGRESS)) { break; } else { /* * don't use if being accepted or * used in any other way */ in_pcb_checkstate(inp, WNT_RELEASE, 1); socket_unlock(so, 1); } } else { /* * do not try to lock the inp in * in_pcb_checkstate because the lock * is already held in some other thread. * Only drop the inp_wntcnt reference. */ in_pcb_checkstate(inp, WNT_RELEASE, 1); } } so = sonext; } if (so == NULL) { socket_lock(head, 0); so_release_accept_list(head); return 0; } /* Makes sure socket is still in the right state to be discarded */ if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) { socket_unlock(so, 1); socket_lock(head, 0); so_release_accept_list(head); return 0; } found_victim: if (so->so_usecount != 2 || !(so->so_state & SS_INCOMP)) { /* do not discard: that socket is being accepted */ socket_unlock(so, 1); socket_lock(head, 0); so_release_accept_list(head); return 0; } socket_lock(head, 0); TAILQ_REMOVE(&head->so_incomp, so, so_list); head->so_incqlen--; head->so_qlen--; so->so_state &= ~SS_INCOMP; so->so_flags |= SOF_OVERFLOW; so->so_head = NULL; so_release_accept_list(head); socket_unlock(head, 0); socket_lock_assert_owned(so); tp = sototcpcb(so); tcp_close(tp); if (inp->inp_wantcnt > 0 && inp->inp_wantcnt != WNT_STOPUSING) { /* * Some one has a wantcnt on this pcb. Since WNT_ACQUIRE * doesn't require a lock, it could have happened while * we are holding the lock. This pcb will have to * be garbage collected later. * Release the reference held for so_incomp queue */ VERIFY(so->so_usecount > 0); so->so_usecount--; socket_unlock(so, 1); } else { /* * Unlock this socket and leave the reference on. * We need to acquire the pcbinfo lock in order to * fully dispose it off */ socket_unlock(so, 0); lck_rw_lock_exclusive(&tcbinfo.ipi_lock); socket_lock(so, 0); /* Release the reference held for so_incomp queue */ VERIFY(so->so_usecount > 0); so->so_usecount--; if (so->so_usecount != 1 || (inp->inp_wantcnt > 0 && inp->inp_wantcnt != WNT_STOPUSING)) { /* * There is an extra wantcount or usecount * that must have been added when the socket * was unlocked. This socket will have to be * garbage collected later */ socket_unlock(so, 1); } else { /* Drop the reference held for this function */ VERIFY(so->so_usecount > 0); so->so_usecount--; in_pcbdispose(inp); } lck_rw_done(&tcbinfo.ipi_lock); } tcpstat.tcps_drops++; socket_lock(head, 0); return 1; } /* Set background congestion control on a socket */ void tcp_set_background_cc(struct socket *so) { tcp_set_new_cc(so, TCP_CC_ALGO_BACKGROUND_INDEX); } /* Set foreground congestion control on a socket */ void tcp_set_foreground_cc(struct socket *so) { if (tcp_use_newreno) { tcp_set_new_cc(so, TCP_CC_ALGO_NEWRENO_INDEX); #if (DEVELOPMENT || DEBUG) } else if (tcp_use_ledbat) { /* Only used for testing */ tcp_set_new_cc(so, TCP_CC_ALGO_BACKGROUND_INDEX); #endif } else { tcp_set_new_cc(so, TCP_CC_ALGO_CUBIC_INDEX); } } static void tcp_set_new_cc(struct socket *so, uint8_t cc_index) { struct inpcb *inp = sotoinpcb(so); struct tcpcb *tp = intotcpcb(inp); if (tp->tcp_cc_index != cc_index) { if (CC_ALGO(tp)->cleanup != NULL) { CC_ALGO(tp)->cleanup(tp); } tp->tcp_cc_index = cc_index; tcp_cc_allocate_state(tp); if (CC_ALGO(tp)->switch_to != NULL) { CC_ALGO(tp)->switch_to(tp); } tcp_ccdbg_trace(tp, NULL, TCP_CC_CHANGE_ALGO); } } void tcp_set_recv_bg(struct socket *so) { if (!IS_TCP_RECV_BG(so)) { so->so_flags1 |= SOF1_TRAFFIC_MGT_TCP_RECVBG; struct inpcb *inp = sotoinpcb(so); struct tcpcb *tp = intotcpcb(inp); if (TCP_RLEDBAT_ENABLED(tp) && tcp_cc_rledbat.switch_to != NULL) { tcp_cc_rledbat.switch_to(tp); } } } void tcp_clear_recv_bg(struct socket *so) { if (IS_TCP_RECV_BG(so)) { so->so_flags1 &= ~(SOF1_TRAFFIC_MGT_TCP_RECVBG); } } void inp_fc_throttle_tcp(struct inpcb *inp) { struct tcpcb *tp = inp->inp_ppcb; if (!tcp_flow_control_response) { return; } /* * Back off the slow-start threshold and enter * congestion avoidance phase */ if (CC_ALGO(tp)->pre_fr != NULL) { CC_ALGO(tp)->pre_fr(tp); } } void inp_fc_unthrottle_tcp(struct inpcb *inp) { struct tcpcb *tp = inp->inp_ppcb; if (tcp_flow_control_response) { if (CC_ALGO(tp)->post_fr != NULL) { CC_ALGO(tp)->post_fr(tp, NULL); } tp->t_bytes_acked = 0; /* * Reset retransmit shift as we know that the reason * for delay in sending a packet is due to flow * control on the outgoing interface. There is no need * to backoff retransmit timer. */ TCP_RESET_REXMT_STATE(tp); tp->t_flagsext &= ~TF_CWND_NONVALIDATED; /* * Start the output stream again. Since we are * not retransmitting data, do not reset the * retransmit timer or rtt calculation. */ tcp_output(tp); return; } /* * Back off the slow-start threshold and enter * congestion avoidance phase */ if (CC_ALGO(tp)->pre_fr != NULL) { CC_ALGO(tp)->pre_fr(tp); } tp->snd_cwnd = tp->snd_ssthresh; tp->t_flagsext &= ~TF_CWND_NONVALIDATED; /* * Restart counting for ABC as we changed the * congestion window just now. */ tp->t_bytes_acked = 0; /* Reset retransmit shift as we know that the reason * for delay in sending a packet is due to flow * control on the outgoing interface. There is no need * to backoff retransmit timer. */ TCP_RESET_REXMT_STATE(tp); /* * Start the output stream again. Since we are * not retransmitting data, do not reset the * retransmit timer or rtt calculation. */ tcp_output(tp); } static int tcp_getstat SYSCTL_HANDLER_ARGS { #pragma unused(oidp, arg1, arg2) int error; struct tcpstat *stat; stat = &tcpstat; #if XNU_TARGET_OS_OSX struct tcpstat zero_stat; if (tcp_disable_access_to_stats && !kauth_cred_issuser(kauth_cred_get())) { bzero(&zero_stat, sizeof(zero_stat)); stat = &zero_stat; } #endif /* XNU_TARGET_OS_OSX */ if (req->oldptr == 0) { req->oldlen = (size_t)sizeof(struct tcpstat); } error = SYSCTL_OUT(req, stat, MIN(sizeof(tcpstat), req->oldlen)); return error; } /* * Checksum extended TCP header and data. */ int tcp_input_checksum(int af, struct mbuf *m, struct tcphdr *th, int off, int tlen) { struct ifnet *ifp = m->m_pkthdr.rcvif; switch (af) { case AF_INET: { struct ip *ip = mtod(m, struct ip *); struct ipovly *ipov = (struct ipovly *)ip; /* ip_stripoptions() must have been called before we get here */ ASSERT((ip->ip_hl << 2) == sizeof(*ip)); if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) || (m->m_pkthdr.pkt_flags & PKTF_LOOP)) && (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) { if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) { th->th_sum = m->m_pkthdr.csum_rx_val; } else { uint32_t sum = m->m_pkthdr.csum_rx_val; uint32_t start = m->m_pkthdr.csum_rx_start; int32_t trailer = (m_pktlen(m) - (off + tlen)); /* * Perform 1's complement adjustment of octets * that got included/excluded in the hardware- * calculated checksum value. Ignore cases * where the value already includes the entire * IP header span, as the sum for those octets * would already be 0 by the time we get here; * IP has already performed its header checksum * checks. If we do need to adjust, restore * the original fields in the IP header when * computing the adjustment value. Also take * care of any trailing bytes and subtract out * their partial sum. */ ASSERT(trailer >= 0); if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) && ((start != 0 && start != off) || trailer)) { uint32_t swbytes = (uint32_t)trailer; if (start < off) { ip->ip_len += sizeof(*ip); #if BYTE_ORDER != BIG_ENDIAN HTONS(ip->ip_len); HTONS(ip->ip_off); #endif /* BYTE_ORDER != BIG_ENDIAN */ } /* callee folds in sum */ sum = m_adj_sum16(m, start, off, tlen, sum); if (off > start) { swbytes += (off - start); } else { swbytes += (start - off); } if (start < off) { #if BYTE_ORDER != BIG_ENDIAN NTOHS(ip->ip_off); NTOHS(ip->ip_len); #endif /* BYTE_ORDER != BIG_ENDIAN */ ip->ip_len -= sizeof(*ip); } if (swbytes != 0) { tcp_in_cksum_stats(swbytes); } if (trailer != 0) { m_adj(m, -trailer); } } /* callee folds in sum */ th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, sum + htonl(tlen + IPPROTO_TCP)); } th->th_sum ^= 0xffff; } else { uint16_t ip_sum; int len; char b[9]; bcopy(ipov->ih_x1, b, sizeof(ipov->ih_x1)); bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); ip_sum = ipov->ih_len; ipov->ih_len = (u_short)tlen; #if BYTE_ORDER != BIG_ENDIAN HTONS(ipov->ih_len); #endif len = sizeof(struct ip) + tlen; th->th_sum = in_cksum(m, len); bcopy(b, ipov->ih_x1, sizeof(ipov->ih_x1)); ipov->ih_len = ip_sum; tcp_in_cksum_stats(len); } break; } case AF_INET6: { struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) || (m->m_pkthdr.pkt_flags & PKTF_LOOP)) && (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) { if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) { th->th_sum = m->m_pkthdr.csum_rx_val; } else { uint32_t sum = m->m_pkthdr.csum_rx_val; uint32_t start = m->m_pkthdr.csum_rx_start; int32_t trailer = (m_pktlen(m) - (off + tlen)); /* * Perform 1's complement adjustment of octets * that got included/excluded in the hardware- * calculated checksum value. Also take care * of any trailing bytes and subtract out their * partial sum. */ ASSERT(trailer >= 0); if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) && (start != off || trailer != 0)) { uint16_t s = 0, d = 0; uint32_t swbytes = (uint32_t)trailer; if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { s = ip6->ip6_src.s6_addr16[1]; ip6->ip6_src.s6_addr16[1] = 0; } if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) { d = ip6->ip6_dst.s6_addr16[1]; ip6->ip6_dst.s6_addr16[1] = 0; } /* callee folds in sum */ sum = m_adj_sum16(m, start, off, tlen, sum); if (off > start) { swbytes += (off - start); } else { swbytes += (start - off); } if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { ip6->ip6_src.s6_addr16[1] = s; } if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) { ip6->ip6_dst.s6_addr16[1] = d; } if (swbytes != 0) { tcp_in6_cksum_stats(swbytes); } if (trailer != 0) { m_adj(m, -trailer); } } th->th_sum = in6_pseudo( &ip6->ip6_src, &ip6->ip6_dst, sum + htonl(tlen + IPPROTO_TCP)); } th->th_sum ^= 0xffff; } else { tcp_in6_cksum_stats(tlen); th->th_sum = in6_cksum(m, IPPROTO_TCP, off, tlen); } break; } default: VERIFY(0); /* NOTREACHED */ } if (th->th_sum != 0) { tcpstat.tcps_rcvbadsum++; IF_TCP_STATINC(ifp, badformat); return -1; } return 0; } #define DUMP_BUF_CHK() { \ clen -= k; \ if (clen < 1) \ goto done; \ c += k; \ } int dump_tcp_reass_qlen(char *str, int str_len) { char *c = str; int k, clen = str_len; if (tcp_reass_total_qlen != 0) { k = scnprintf(c, clen, "\ntcp reass qlen %d\n", tcp_reass_total_qlen); DUMP_BUF_CHK(); } done: return str_len - clen; } uint32_t tcp_reass_qlen_space(struct socket *so) { uint32_t space = 0; struct inpcb *inp = sotoinpcb(so); if (inp != NULL) { struct tcpcb *tp = intotcpcb(inp); if (tp != NULL) { space = tp->t_reassq_mbcnt; } } return space; } SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0, tcp_getstat, "S,tcpstat", "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); static int sysctl_rexmtthresh SYSCTL_HANDLER_ARGS { #pragma unused(arg1, arg2) int error, val = tcprexmtthresh; error = sysctl_handle_int(oidp, &val, 0, req); if (error || !req->newptr) { return error; } /* * Constrain the number of duplicate ACKs * to consider for TCP fast retransmit * to either 2 or 3 */ if (val < 2 || val > 3) { return EINVAL; } tcprexmtthresh = (uint8_t)val; return 0; } SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmt_thresh, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &tcprexmtthresh, 0, &sysctl_rexmtthresh, "I", "Duplicate ACK Threshold for Fast Retransmit");