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gems-kernel/source/THIRDPARTY/xnu/bsd/netinet/tcp_input.c
Sam Sneed f5727805f2 add darwin/xnu functionality
2024-06-03 11:29:39 -05:00

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/*
* 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 <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h> /* for proc0 declaration */
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/syslog.h>
#include <sys/mcache.h>
#include <sys/kauth.h>
#include <kern/cpu_number.h> /* before tcp_seq.h, for tcp_random18() */
#include <machine/endian.h>
#include <net/if.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/ntstat.h>
#include <net/content_filter.h>
#include <net/dlil.h>
#include <net/multi_layer_pkt_log.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */
#include <netinet/in_var.h>
#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <mach/sdt.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet/tcp.h>
#include <netinet/tcp_cache.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcp_cc.h>
#include <dev/random/randomdev.h>
#include <kern/zalloc.h>
#include <netinet6/tcp6_var.h>
#include <netinet/tcpip.h>
#if TCPDEBUG
#include <netinet/tcp_debug.h>
u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */
struct tcphdr tcp_savetcp;
#endif /* TCPDEBUG */
#include <netinet/tcp_log.h>
#if IPSEC
#include <netinet6/ipsec.h>
#include <netinet6/ipsec6.h>
#include <netkey/key.h>
#endif /*IPSEC*/
#include <sys/kdebug.h>
#if MPTCP
#include <netinet/mptcp_var.h>
#include <netinet/mptcp.h>
#include <netinet/mptcp_opt.h>
#endif /* MPTCP */
#include <corecrypto/ccaes.h>
#include <net/sockaddr_utils.h>
#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:
* <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
* 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 <SYN,ACK> 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.
* <rdar://problem/28739046>
*/
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");
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