/*
* Copyright (c) 2000-2024 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, 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_output.c 8.4 (Berkeley) 5/24/95
* $FreeBSD: src/sys/netinet/tcp_output.c,v 1.39.2.10 2001/07/07 04:30:38 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.
*/
#define _IP_VHL
#include "tcp_includes.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <os/ptrtools.h>
#include <net/route.h>
#include <net/ntstat.h>
#include <net/if_var.h>
#include <net/if.h>
#include <net/if_types.h>
#include <net/dlil.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/in_tclass.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <mach/sdt.h>
#include <netinet6/in6_pcb.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.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/tcpip.h>
#include <netinet/tcp_cc.h>
#include <netinet/tcp_log.h>
#include <sys/kdebug.h>
#include <mach/sdt.h>
#if IPSEC
#include <netinet6/ipsec.h>
#endif /*IPSEC*/
#if MPTCP
#include <netinet/mptcp_var.h>
#include <netinet/mptcp.h>
#include <netinet/mptcp_opt.h>
#include <netinet/mptcp_seq.h>
#endif
#include <corecrypto/ccaes.h>
#define DBG_LAYER_BEG NETDBG_CODE(DBG_NETTCP, 1)
#define DBG_LAYER_END NETDBG_CODE(DBG_NETTCP, 3)
#define DBG_FNC_TCP_OUTPUT NETDBG_CODE(DBG_NETTCP, (4 << 8) | 1)
SYSCTL_SKMEM_TCP_INT(OID_AUTO, path_mtu_discovery,
CTLFLAG_RW | CTLFLAG_LOCKED, int, path_mtu_discovery, 1,
"Enable Path MTU Discovery");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, local_slowstart_flightsize,
CTLFLAG_RW | CTLFLAG_LOCKED, int, ss_fltsz_local, 8,
"Slow start flight size for local networks");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, tso, CTLFLAG_RW | CTLFLAG_LOCKED,
int, tcp_do_tso, 1, "Enable TCP Segmentation Offload");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, ecn_setup_percentage,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_ecn_setup_percentage, 100,
"Max ECN setup percentage");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, accurate_ecn,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_acc_ecn, 0,
"Accurate ECN mode (0: disable, 1: enable Accurate ECN feedback");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, l4s,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_l4s, 0,
"L4S mode (0: disable, 1: enable L4S");
// TO BE REMOVED
SYSCTL_SKMEM_TCP_INT(OID_AUTO, do_ack_compression,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_do_ack_compression, 1,
"Enable TCP ACK compression (on (cell only): 1, off: 0, on (all interfaces): 2)");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, ack_compression_rate,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_ack_compression_rate, TCP_COMP_CHANGE_RATE,
"Rate at which we force sending new ACKs (in ms)");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, randomize_timestamps,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_randomize_timestamps, 1,
"Randomize TCP timestamps to prevent tracking (on: 1, off: 0)");
static int
sysctl_change_ecn_setting SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp, arg1, arg2)
int i, err = 0, changed = 0;
ifnet_ref_t ifp;
err = sysctl_io_number(req, tcp_ecn_outbound, sizeof(int32_t),
&i, &changed);
if (err != 0 || req->newptr == USER_ADDR_NULL) {
return err;
}
if (changed) {
if ((tcp_ecn_outbound == 0 || tcp_ecn_outbound == 1) &&
(i == 0 || i == 1)) {
tcp_ecn_outbound = i;
SYSCTL_SKMEM_UPDATE_FIELD(tcp.ecn_initiate_out, tcp_ecn_outbound);
return err;
}
if (tcp_ecn_outbound == 2 && (i == 0 || i == 1)) {
/*
* Reset ECN enable flags on non-cellular
* interfaces so that the system default will take
* over
*/
ifnet_head_lock_shared();
TAILQ_FOREACH(ifp, &ifnet_head, if_link) {
if (!IFNET_IS_CELLULAR(ifp)) {
if_clear_eflags(ifp,
IFEF_ECN_ENABLE |
IFEF_ECN_DISABLE);
}
}
ifnet_head_done();
} else {
/*
* Set ECN enable flags on non-cellular
* interfaces
*/
ifnet_head_lock_shared();
TAILQ_FOREACH(ifp, &ifnet_head, if_link) {
if (!IFNET_IS_CELLULAR(ifp)) {
if_set_eflags(ifp, IFEF_ECN_ENABLE);
if_clear_eflags(ifp, IFEF_ECN_DISABLE);
}
}
ifnet_head_done();
}
tcp_ecn_outbound = i;
SYSCTL_SKMEM_UPDATE_FIELD(tcp.ecn_initiate_out, tcp_ecn_outbound);
}
/* Change the other one too as the work is done */
if (i == 2 || tcp_ecn_inbound == 2) {
tcp_ecn_inbound = i;
SYSCTL_SKMEM_UPDATE_FIELD(tcp.ecn_negotiate_in, tcp_ecn_inbound);
}
return err;
}
int tcp_ecn_outbound = 2;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, ecn_initiate_out,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_ecn_outbound, 0,
sysctl_change_ecn_setting, "IU",
"Initiate ECN for outbound connections");
int tcp_ecn_inbound = 2;
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, ecn_negotiate_in,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_ecn_inbound, 0,
sysctl_change_ecn_setting, "IU",
"Initiate ECN for inbound connections");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, packetchain,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_packet_chaining, 50,
"Enable TCP output packet chaining");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, socket_unlocked_on_output,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_output_unlocked, 1,
"Unlock TCP when sending packets down to IP");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, min_iaj_win,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_min_iaj_win, MIN_IAJ_WIN,
"Minimum recv win based on inter-packet arrival jitter");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, acc_iaj_react_limit,
CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_acc_iaj_react_limit,
ACC_IAJ_REACT_LIMIT, "Accumulated IAJ when receiver starts to react");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, autosndbufinc,
CTLFLAG_RW | CTLFLAG_LOCKED, uint32_t, tcp_autosndbuf_inc,
8 * 1024, "Increment in send socket bufffer size");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, autosndbufmax,
CTLFLAG_RW | CTLFLAG_LOCKED | CTLFLAG_KERN, uint32_t, tcp_autosndbuf_max, 2 * 1024 * 1024,
"Maximum send socket buffer size");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, rtt_recvbg,
CTLFLAG_RW | CTLFLAG_LOCKED, uint32_t, tcp_use_rtt_recvbg, 1,
"Use RTT for bg recv algorithm");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, recv_throttle_minwin,
CTLFLAG_RW | CTLFLAG_LOCKED, uint32_t, tcp_recv_throttle_minwin, 16 * 1024,
"Minimum recv win for throttling");
SYSCTL_SKMEM_TCP_INT(OID_AUTO, enable_tlp,
CTLFLAG_RW | CTLFLAG_LOCKED,
int32_t, tcp_enable_tlp, 1, "Enable Tail loss probe");
static int32_t packchain_newlist = 0;
static int32_t packchain_looped = 0;
static int32_t packchain_sent = 0;
/* temporary: for testing */
#if IPSEC
extern int ipsec_bypass;
#endif
extern int slowlink_wsize; /* window correction for slow links */
extern u_int32_t kipf_count;
static int tcp_ip_output(struct socket *, struct tcpcb *, struct mbuf *,
int, struct mbuf *, int, int, boolean_t);
static int tcp_recv_throttle(struct tcpcb *tp);
__attribute__((noinline))
static int32_t
tcp_tfo_check(struct tcpcb *tp, int32_t len)
{
struct socket *__single so = tp->t_inpcb->inp_socket;
unsigned int optlen = 0;
unsigned int cookie_len;
if (tp->t_flags & TF_NOOPT) {
goto fallback;
}
if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) &&
!tcp_heuristic_do_tfo(tp)) {
tp->t_tfo_stats |= TFO_S_HEURISTICS_DISABLE;
tcpstat.tcps_tfo_heuristics_disable++;
goto fallback;
}
if (so->so_flags1 & SOF1_DATA_AUTHENTICATED) {
return len;
}
optlen += TCPOLEN_MAXSEG;
if (tp->t_flags & TF_REQ_SCALE) {
optlen += 4;
}
#if MPTCP
if ((so->so_flags & SOF_MP_SUBFLOW) && mptcp_enable &&
(tp->t_rxtshift <= mptcp_mpcap_retries ||
(tptomptp(tp)->mpt_mpte->mpte_flags & MPTE_FORCE_ENABLE))) {
optlen += sizeof(struct mptcp_mpcapable_opt_common) + sizeof(mptcp_key_t);
}
#endif /* MPTCP */
if (tp->t_flags & TF_REQ_TSTMP) {
optlen += TCPOLEN_TSTAMP_APPA;
}
if (SACK_ENABLED(tp)) {
optlen += TCPOLEN_SACK_PERMITTED;
}
/* Now, decide whether to use TFO or not */
/* Don't even bother trying if there is no space at all... */
if (MAX_TCPOPTLEN - optlen < TCPOLEN_FASTOPEN_REQ) {
goto fallback;
}
cookie_len = tcp_cache_get_cookie_len(tp);
if (cookie_len == 0) {
/* No cookie, so we request one */
return 0;
}
/* There is not enough space for the cookie, so we cannot do TFO */
if (MAX_TCPOPTLEN - optlen < cookie_len) {
goto fallback;
}
/* Do not send SYN+data if there is more in the queue than MSS */
if (so->so_snd.sb_cc > (tp->t_maxopd - MAX_TCPOPTLEN)) {
goto fallback;
}
/* Ok, everything looks good. We can go on and do TFO */
return len;
fallback:
tcp_disable_tfo(tp);
return 0;
}
/* Returns the number of bytes written to the TCP option-space */
__attribute__((noinline))
static unsigned int
tcp_tfo_write_cookie_rep(struct tcpcb *tp, unsigned int optlen,
u_char *__counted_by(optlen + 2 + TFO_COOKIE_LEN_DEFAULT) opt)
{
u_char out[CCAES_BLOCK_SIZE];
unsigned ret = 0;
u_char *bp;
if (MAX_TCPOPTLEN - optlen <
TCPOLEN_FASTOPEN_REQ + TFO_COOKIE_LEN_DEFAULT) {
return ret;
}
tcp_tfo_gen_cookie(tp->t_inpcb, out, sizeof(out));
bp = opt + optlen;
*bp++ = TCPOPT_FASTOPEN;
*bp++ = 2 + TFO_COOKIE_LEN_DEFAULT;
memcpy(bp, out, TFO_COOKIE_LEN_DEFAULT);
ret += 2 + TFO_COOKIE_LEN_DEFAULT;
tp->t_tfo_stats |= TFO_S_COOKIE_SENT;
tcpstat.tcps_tfo_cookie_sent++;
return ret;
}
__attribute__((noinline))
static unsigned int
tcp_tfo_write_cookie(struct tcpcb *tp, unsigned int optlen, int32_t len,
u_char *__counted_by(TCP_MAXOLEN) opt)
{
uint8_t tfo_len;
struct socket *__single so = tp->t_inpcb->inp_socket;
unsigned ret = 0;
int res;
u_char *bp;
if (TCPOLEN_FASTOPEN_REQ > MAX_TCPOPTLEN - optlen) {
return 0;
}
tfo_len = (uint8_t)(MAX_TCPOPTLEN - optlen - TCPOLEN_FASTOPEN_REQ);
if (so->so_flags1 & SOF1_DATA_AUTHENTICATED) {
/* If there is some data, let's track it */
if (len > 0) {
tp->t_tfo_stats |= TFO_S_SYN_DATA_SENT;
tcpstat.tcps_tfo_syn_data_sent++;
}
return 0;
}
bp = opt + optlen;
/*
* The cookie will be copied in the appropriate place within the
* TCP-option space. That way we avoid the need for an intermediate
* variable.
*/
res = tcp_cache_get_cookie(tp, bp + TCPOLEN_FASTOPEN_REQ, tfo_len, &tfo_len);
if (res == 0) {
*bp++ = TCPOPT_FASTOPEN;
*bp++ = TCPOLEN_FASTOPEN_REQ;
ret += TCPOLEN_FASTOPEN_REQ;
tp->t_tfo_flags |= TFO_F_COOKIE_REQ;
tp->t_tfo_stats |= TFO_S_COOKIE_REQ;
tcpstat.tcps_tfo_cookie_req++;
} else {
*bp++ = TCPOPT_FASTOPEN;
*bp++ = TCPOLEN_FASTOPEN_REQ + tfo_len;
ret += TCPOLEN_FASTOPEN_REQ + tfo_len;
tp->t_tfo_flags |= TFO_F_COOKIE_SENT;
/* If there is some data, let's track it */
if (len > 0) {
tp->t_tfo_stats |= TFO_S_SYN_DATA_SENT;
tcpstat.tcps_tfo_syn_data_sent++;
}
}
return ret;
}
static inline bool
tcp_send_ecn_flags_on_syn(struct tcpcb *tp)
{
/* We allow Accurate ECN negotiation on first retransmission as well */
bool send_on_first_retrans = (tp->ecn_flags & TE_ACE_SETUPSENT) &&
(tp->t_rxtshift <= 1);
return !(tp->ecn_flags & (TE_SETUPSENT | TE_ACE_SETUPSENT)) || send_on_first_retrans;
}
void
tcp_set_ecn(struct tcpcb *tp, struct ifnet *ifp)
{
boolean_t inbound;
/*
* Socket option has precedence
*/
if (tp->ecn_flags & TE_ECN_MODE_ENABLE) {
tp->ecn_flags |= TE_ENABLE_ECN;
goto check_heuristic;
}
if (tp->ecn_flags & TE_ECN_MODE_DISABLE) {
tp->ecn_flags &= ~TE_ENABLE_ECN;
return;
}
/*
* Per interface setting comes next
*/
if (ifp != NULL) {
if (ifp->if_eflags & IFEF_ECN_ENABLE) {
tp->ecn_flags |= TE_ENABLE_ECN;
goto check_heuristic;
}
if (ifp->if_eflags & IFEF_ECN_DISABLE) {
tp->ecn_flags &= ~TE_ENABLE_ECN;
return;
}
}
/*
* System wide settings come last
*/
inbound = (tp->t_inpcb->inp_socket->so_head != NULL);
if ((inbound && tcp_ecn_inbound == 1) ||
(!inbound && tcp_ecn_outbound == 1)) {
tp->ecn_flags |= TE_ENABLE_ECN;
goto check_heuristic;
} else {
tp->ecn_flags &= ~TE_ENABLE_ECN;
}
return;
check_heuristic:
if (TCP_ACC_ECN_ENABLED(tp)) {
/* Allow ECN when Accurate ECN is enabled until heuristics are fixed */
tp->ecn_flags |= TE_ENABLE_ECN;
/* Set the accurate ECN state */
if (tp->t_client_accecn_state == tcp_connection_client_accurate_ecn_feature_disabled) {
tp->t_client_accecn_state = tcp_connection_client_accurate_ecn_feature_enabled;
}
if (tp->t_server_accecn_state == tcp_connection_server_accurate_ecn_feature_disabled) {
tp->t_server_accecn_state = tcp_connection_server_accurate_ecn_feature_enabled;
}
}
if (!tcp_heuristic_do_ecn(tp) && !TCP_ACC_ECN_ENABLED(tp)) {
/* Allow ECN when Accurate ECN is enabled until heuristics are fixed */
tp->ecn_flags &= ~TE_ENABLE_ECN;
}
/*
* If the interface setting, system-level setting and heuristics
* allow to enable ECN, randomly select 5% of connections to
* enable it
*/
if ((tp->ecn_flags & (TE_ECN_MODE_ENABLE | TE_ECN_MODE_DISABLE
| TE_ENABLE_ECN)) == TE_ENABLE_ECN) {
/*
* Use the random value in iss for randomizing
* this selection
*/
if ((tp->iss % 100) >= tcp_ecn_setup_percentage && !TCP_ACC_ECN_ENABLED(tp)) {
/* Don't disable Accurate ECN randomly */
tp->ecn_flags &= ~TE_ENABLE_ECN;
}
}
}
uint32_t
tcp_flight_size(struct tcpcb *tp)
{
int ret;
VERIFY(tp->sackhint.sack_bytes_acked >= 0);
VERIFY(tp->sackhint.sack_bytes_rexmit >= 0);
/*
* RFC6675, SetPipe (), SACK'd bytes are discounted. All the rest is still in-flight.
*/
ret = tp->snd_nxt - tp->snd_una - tp->sackhint.sack_bytes_acked;
if (TCP_RACK_ENABLED(tp)) {
/* In flight is bytes sent - bytes that left the network + bytes retransmitted */
const uint32_t bytes_sent = SEQ_MAX(tp->snd_max, tp->snd_nxt) - tp->snd_una;
const uint32_t bytes_not_in_flight = tp->bytes_sacked + tp->bytes_lost;
ret = bytes_sent - bytes_not_in_flight + tp->bytes_retransmitted;
}
if (ret < 0) {
/* It shouldn't happen when RACK is enabled */
if (TCP_RACK_ENABLED(tp)) {
os_log_error(OS_LOG_DEFAULT, "flight_size (%d) can't be negative "
"(snd_nxt:%u snd_max:%u, snd_una:%u, sacked:%u lost:%u retransmitted:%u)",
ret, tp->snd_nxt, tp->snd_max, tp->snd_una,
tp->bytes_sacked, tp->bytes_lost, tp->bytes_retransmitted);
}
/*
* This happens when the RTO-timer fires because snd_nxt gets artificially
* decreased. If we then receive some SACK-blogs, sack_bytes_acked is
* going to be high.
*/
ret = 0;
}
return ret;
}
/*
* Either of ECT0 or ECT1 flag should be set
* when this function is called
*/
static void
tcp_add_accecn_option(struct tcpcb *tp, uint16_t flags, uint32_t *__indexable lp, uint8_t *optlen)
{
uint8_t max_len = TCP_MAXOLEN - *optlen;
uint8_t len = TCPOLEN_ACCECN_EMPTY;
uint32_t e1b = (uint32_t)(tp->t_aecn.t_rcv_ect1_bytes & TCP_ACO_MASK);
uint32_t e0b = (uint32_t)(tp->t_aecn.t_rcv_ect0_bytes & TCP_ACO_MASK);
uint32_t ceb = (uint32_t)(tp->t_aecn.t_rcv_ce_bytes & TCP_ACO_MASK);
if (max_len < TCPOLEN_ACCECN_EMPTY) {
TCP_LOG(tp, "not enough space to add any AccECN option");
return;
}
if (!(flags & TH_SYN || (tp->ecn_flags & TE_ACE_FINAL_ACK_3WHS) ||
tp->snd_una == tp->iss + 1 ||
tp->ecn_flags & (TE_ACO_ECT1 | TE_ACO_ECT0))) {
/*
* Since this is neither a SYN-ACK packet, nor the final ACK of
* the 3WHS (nor the first acked data segment) nor any of the ECT byte
* counter flags are set, no need to send the option.
*/
return;
}
if ((flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK) &&
tp->t_rxtshift >= 1) {
/*
* If this is a SYN-ACK retransmission (first),
* retry without AccECN option and just with ACE fields.
* From second retransmission onwards, we don't send any
* Accurate ECN state.
*/
return;
}
if (max_len < (TCPOLEN_ACCECN_EMPTY + 1 * TCPOLEN_ACCECN_COUNTER)) {
/* Can carry EMPTY option which can be used to test path in SYN-ACK packet */
if (flags & TH_SYN) {
*lp++ = htonl((TCPOPT_ACCECN1 << 24) | (len << 16) |
(TCPOPT_NOP << 8) | TCPOPT_NOP);
*optlen += len + 2; /* 2 NOPs */
TCP_LOG(tp, "add empty AccECN option, optlen=%u", *optlen);
}
} else if (max_len < (TCPOLEN_ACCECN_EMPTY + 2 * TCPOLEN_ACCECN_COUNTER)) {
/* Can carry one option */
len += 1 * TCPOLEN_ACCECN_COUNTER;
if (tp->ecn_flags & TE_ACO_ECT1) {
*lp++ = htonl((TCPOPT_ACCECN1 << 24) | (len << 16) | ((e1b >> 8) & 0xffff));
*lp++ = htonl(((e1b & 0xff) << 24) | (TCPOPT_NOP << 16) | (TCPOPT_NOP << 8) | TCPOPT_NOP);
} else {
*lp++ = htonl((TCPOPT_ACCECN0 << 24) | (len << 16) | ((e0b >> 8) & 0xffff));
*lp++ = htonl(((e0b & 0xff) << 24) | (TCPOPT_NOP << 16) | (TCPOPT_NOP << 8) | TCPOPT_NOP);
}
*optlen += len + 3; /* 3 NOPs */
TCP_LOG(tp, "add single counter for AccECN option, optlen=%u", *optlen);
} else if (max_len < (TCPOLEN_ACCECN_EMPTY + 3 * TCPOLEN_ACCECN_COUNTER)) {
/* Can carry two options */
len += 2 * TCPOLEN_ACCECN_COUNTER;
if (tp->ecn_flags & TE_ACO_ECT1) {
*lp++ = htonl((TCPOPT_ACCECN1 << 24) | (len << 16) | ((e1b >> 8) & 0xffff));
*lp++ = htonl(((e1b & 0xff) << 24) | (ceb & 0xffffff));
} else {
*lp++ = htonl((TCPOPT_ACCECN0 << 24) | (len << 16) | ((e0b >> 8) & 0xffff));
*lp++ = htonl(((e0b & 0xff) << 24) | (ceb & 0xffffff));
}
*optlen += len; /* 0 NOPs */
TCP_LOG(tp, "add 2 counters for AccECN option, optlen=%u", *optlen);
} else {
/*
* TCP option sufficient to hold full AccECN option
* but send counter that changed during the entire connection.
*/
len += 3 * TCPOLEN_ACCECN_COUNTER;
/* Can carry all three options */
if (tp->ecn_flags & TE_ACO_ECT1) {
*lp++ = htonl((TCPOPT_ACCECN1 << 24) | (len << 16) | ((e1b >> 8) & 0xffff));
*lp++ = htonl(((e1b & 0xff) << 24) | (ceb & 0xffffff));
*lp++ = htonl(((e0b & 0xffffff) << 8) | TCPOPT_NOP);
} else {
*lp++ = htonl((TCPOPT_ACCECN0 << 24) | (len << 16) | ((e0b >> 8) & 0xffff));
*lp++ = htonl(((e0b & 0xff) << 24) | (ceb & 0xffffff));
*lp++ = htonl(((e1b & 0xffffff) << 8) | TCPOPT_NOP);
}
*optlen += len + 1; /* 1 NOP */
TCP_LOG(tp, "add all 3 counters for AccECN option, optlen=%u", *optlen);
}
}
/*
* Tcp output routine: figure out what should be sent and send it.
*
* Returns: 0 Success
* EADDRNOTAVAIL
* ENOBUFS
* EMSGSIZE
* EHOSTUNREACH
* ENETDOWN
* ip_output_list:ENOMEM
* ip_output_list:EADDRNOTAVAIL
* ip_output_list:ENETUNREACH
* ip_output_list:EHOSTUNREACH
* ip_output_list:EACCES
* ip_output_list:EMSGSIZE
* ip_output_list:ENOBUFS
* ip_output_list:??? [ignorable: mostly IPSEC/firewall/DLIL]
* ip6_output_list:EINVAL
* ip6_output_list:EOPNOTSUPP
* ip6_output_list:EHOSTUNREACH
* ip6_output_list:EADDRNOTAVAIL
* ip6_output_list:ENETUNREACH
* ip6_output_list:EMSGSIZE
* ip6_output_list:ENOBUFS
* ip6_output_list:??? [ignorable: mostly IPSEC/firewall/DLIL]
*/
int
tcp_output(struct tcpcb *tp)
{
uint32_t tcp_now_local = os_access_once(tcp_now);
struct inpcb *__single inp = tp->t_inpcb;
struct socket *__single so = inp->inp_socket;
int32_t len, recwin, sendwin, off;
uint32_t max_len = 0;
uint16_t flags;
int error;
mbuf_ref_t m;
struct ip *ip = NULL;
struct ip6_hdr *ip6 = NULL;
struct tcphdr *th;
u_char opt[TCP_MAXOLEN];
unsigned int ipoptlen, optlen, hdrlen;
int idle, sendalot, lost = 0;
int sendalot_cnt = 0;
int i, rack_sack_rxmit = 0;
int tso = 0;
int sack_bytes_rxmt;
tcp_seq old_snd_nxt = 0;
struct sackhole *p;
struct tcp_seg_sent *seg;
#if IPSEC
size_t ipsec_optlen = 0;
#endif /* IPSEC */
int idle_time = 0;
struct mbuf *__single packetlist = NULL;
struct mbuf *__single tp_inp_options = inp->inp_depend4.inp4_options;
int isipv6 = inp->inp_vflag & INP_IPV6;
int packchain_listadd = 0;
int so_options = so->so_options;
rtentry_ref_t rt;
u_int32_t svc_flags = 0, allocated_len;
#if MPTCP
boolean_t mptcp_acknow;
#endif /* MPTCP */
stats_functional_type ifnet_count_type = stats_functional_type_none;
boolean_t sack_rescue_rxt = FALSE;
int sotc = so->so_traffic_class;
boolean_t do_not_compress = FALSE;
boolean_t sack_rxmted = FALSE;
/*
* Determine length of data that should be transmitted,
* and flags that will be used.
* If there is some data or critical controls (SYN, RST)
* to send, then transmit; otherwise, investigate further.
*/
idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una);
/* Since idle_time is signed integer, the following integer subtraction
* will take care of wrap around of tcp_now
*/
idle_time = tcp_now_local - tp->t_rcvtime;
if (idle && idle_time >= TCP_IDLETIMEOUT(tp)) {
if (CC_ALGO(tp)->after_idle != NULL &&
((tp->tcp_cc_index != TCP_CC_ALGO_CUBIC_INDEX &&
tp->tcp_cc_index != TCP_CC_ALGO_PRAGUE_INDEX) ||
idle_time >= TCP_CC_CWND_NONVALIDATED_PERIOD)) {
CC_ALGO(tp)->after_idle(tp);
tcp_ccdbg_trace(tp, NULL, TCP_CC_IDLE_TIMEOUT);
}
/*
* Do some other tasks that need to be done after
* idle time
*/
if (!SLIST_EMPTY(&tp->t_rxt_segments)) {
tcp_rxtseg_clean(tp);
}
/* If stretch ack was auto-disabled, re-evaluate it */
tcp_cc_after_idle_stretchack(tp);
tp->t_forced_acks = TCP_FORCED_ACKS_COUNT;
}
tp->t_flags &= ~TF_LASTIDLE;
if (idle) {
if (tp->t_flags & TF_MORETOCOME) {
tp->t_flags |= TF_LASTIDLE;
idle = 0;
}
}
#if MPTCP
if (tp->t_mpflags & TMPF_RESET) {
tcp_check_timer_state(tp);
/*
* Once a RST has been sent for an MPTCP subflow,
* the subflow socket stays around until deleted.
* No packets such as FINs must be sent after RST.
*/
return 0;
}
#endif /* MPTCP */
again:
tcp_now_local = os_access_once(tcp_now);
#if MPTCP
mptcp_acknow = FALSE;
if (so->so_flags & SOF_MP_SUBFLOW && SEQ_LT(tp->snd_nxt, tp->snd_una)) {
os_log_error(mptcp_log_handle, "%s - %lx: snd_nxt is %u and snd_una is %u, cnt %d\n",
__func__, (unsigned long)VM_KERNEL_ADDRPERM(tp->t_mpsub->mpts_mpte),
tp->snd_nxt, tp->snd_una, sendalot_cnt);
}
#endif
do_not_compress = FALSE;
sendalot_cnt++;
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_START, 0, 0, 0, 0, 0);
if (isipv6) {
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)),
sendalot, 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)),
sendalot, 0, 0);
}
/*
* If the route generation id changed, we need to check that our
* local (source) IP address is still valid. If it isn't either
* return error or silently do nothing (assuming the address will
* come back before the TCP connection times out).
*/
rt = inp->inp_route.ro_rt;
if (rt != NULL && ROUTE_UNUSABLE(&tp->t_inpcb->inp_route)) {
struct ifnet *ifp;
struct in_ifaddr *ia = NULL;
struct in6_ifaddr *ia6 = NULL;
int found_srcaddr = 0;
/* disable multipages at the socket */
somultipages(so, FALSE);
/* Disable TSO for the socket until we know more */
tp->t_flags &= ~TF_TSO;
soif2kcl(so, FALSE);
if (isipv6) {
ia6 = ifa_foraddr6(&inp->in6p_laddr);
if (ia6 != NULL) {
found_srcaddr = 1;
}
} else {
ia = ifa_foraddr(inp->inp_laddr.s_addr);
if (ia != NULL) {
found_srcaddr = 1;
}
}
/* check that the source address is still valid */
if (found_srcaddr == 0) {
soevent(so,
(SO_FILT_HINT_LOCKED | SO_FILT_HINT_NOSRCADDR));
if (tp->t_state >= TCPS_CLOSE_WAIT) {
tcp_drop(tp, EADDRNOTAVAIL);
return EADDRNOTAVAIL;
}
/*
* Set retransmit timer if it wasn't set,
* reset Persist timer and shift register as the
* advertised peer window may not be valid anymore
*/
if (tp->t_timer[TCPT_REXMT] == 0) {
tp->t_timer[TCPT_REXMT] =
OFFSET_FROM_START(tp, tp->t_rxtcur);
if (tp->t_timer[TCPT_PERSIST] != 0) {
tp->t_timer[TCPT_PERSIST] = 0;
tp->t_persist_stop = 0;
TCP_RESET_REXMT_STATE(tp);
}
}
if (tp->t_pktlist_head != NULL) {
m_freem_list(tp->t_pktlist_head);
}
TCP_PKTLIST_CLEAR(tp);
/* drop connection if source address isn't available */
if (so->so_flags & SOF_NOADDRAVAIL) {
tcp_drop(tp, EADDRNOTAVAIL);
return EADDRNOTAVAIL;
} else {
TCP_LOG_OUTPUT(tp, "no source address silently ignored");
tcp_check_timer_state(tp);
return 0; /* silently ignore, keep data in socket: address may be back */
}
}
if (ia != NULL) {
ifa_remref(&ia->ia_ifa);
}
if (ia6 != NULL) {
ifa_remref(&ia6->ia_ifa);
}
/*
* Address is still valid; check for multipages capability
* again in case the outgoing interface has changed.
*/
RT_LOCK(rt);
if ((ifp = rt->rt_ifp) != NULL) {
somultipages(so, (ifp->if_hwassist & IFNET_MULTIPAGES));
tcp_set_tso(tp, ifp);
soif2kcl(so, (ifp->if_eflags & IFEF_2KCL));
tcp_set_ecn(tp, ifp);
}
if (rt->rt_flags & RTF_UP) {
RT_GENID_SYNC(rt);
}
/*
* See if we should do MTU discovery. Don't do it if:
* 1) it is disabled via the sysctl
* 2) the route isn't up
* 3) the MTU is locked (if it is, then discovery
* has been disabled)
*/
if (!path_mtu_discovery || ((rt != NULL) &&
(!(rt->rt_flags & RTF_UP) ||
(rt->rt_rmx.rmx_locks & RTV_MTU)))) {
tp->t_flags &= ~TF_PMTUD;
} else {
tp->t_flags |= TF_PMTUD;
}
RT_UNLOCK(rt);
}
if (rt != NULL) {
ifnet_count_type = IFNET_COUNT_TYPE(rt->rt_ifp);
}
/*
* If we've recently taken a timeout, snd_max will be greater than
* snd_nxt. There may be SACK information that allows us to avoid
* resending already delivered data. Adjust snd_nxt accordingly.
* It is ok to use this function with RACK as well as it is estimating
* max_len based on a SACK hole.
*/
if (SACK_ENABLED(tp) && SEQ_LT(tp->snd_nxt, tp->snd_max)) {
if (TCP_RACK_ENABLED(tp)) {
/*
* Calculated in the same manner as when rack_in_recovery
* is set and new data is transmitted after retransmitted data
*/
int32_t cwin = tp->snd_cwnd - tcp_flight_size(tp);
if (cwin > 0) {
max_len = tcp_rack_adjust(tp, (uint32_t)cwin);
}
} else {
max_len = tcp_sack_adjust(tp);
}
}
sendalot = 0;
off = tp->snd_nxt - tp->snd_una;
sendwin = min(tp->snd_wnd, tp->snd_cwnd);
if (tp->t_flags & TF_SLOWLINK && slowlink_wsize > 0) {
sendwin = min(sendwin, slowlink_wsize);
}
flags = tcp_outflags[tp->t_state];
/*
* Send any SACK-generated retransmissions. If we're explicitly
* trying to send out new data (when sendalot is 1), bypass this
* function. If we retransmit in fast recovery mode, decrement
* snd_cwnd, since we're replacing a (future) new transmission
* with a retransmission now, and we previously incremented
* snd_cwnd in tcp_input().
*/
/*
* Still in sack recovery, reset rxmit flag to zero.
*/
rack_sack_rxmit = 0;
sack_bytes_rxmt = 0;
len = 0;
p = NULL;
seg = NULL;
if (SACK_ENABLED(tp) && IN_FASTRECOVERY(tp)) {
int32_t cwin = min(tp->snd_wnd, tp->snd_cwnd) - tcp_flight_size(tp);
if (cwin <= 0 && sack_rxmted == FALSE) {
/* Allow to clock out at least on per period */
cwin = tp->t_maxseg;
}
sack_rxmted = TRUE;
if (cwin < 0) {
cwin = 0;
}
if (TCP_RACK_ENABLED(tp)) {
uint16_t rack_seg_len = 0;
if ((seg = tcp_rack_output(tp, cwin, &rack_seg_len)) != NULL) {
len = min(cwin, rack_seg_len);
if (len > 0) {
off = seg->start_seq - tp->snd_una;
rack_sack_rxmit = 1;
sendalot = 1;
tcpstat.tcps_rack_rexmits++;
} else {
seg = NULL;
}
}
} else if ((p = tcp_sack_output(tp, &sack_bytes_rxmt)) != NULL) {
/* Do not retransmit SACK segments beyond snd_recover */
if (SEQ_GT(p->end, tp->snd_recover)) {
/*
* (At least) part of sack hole extends beyond
* snd_recover. Check to see if we can rexmit data
* for this hole.
*/
if (SEQ_GEQ(p->rxmit, tp->snd_recover)) {
/*
* Can't rexmit any more data for this hole.
* That data will be rexmitted in the next
* sack recovery episode, when snd_recover
* moves past p->rxmit.
*/
p = NULL;
goto after_sack_rexmit;
} else {
/* Can rexmit part of the current hole */
len = ((int32_t)min(cwin,
tp->snd_recover - p->rxmit));
}
} else {
len = ((int32_t)min(cwin, p->end - p->rxmit));
}
if (len > 0) {
off = p->rxmit - tp->snd_una;
rack_sack_rxmit = 1;
sendalot = 1;
/*
* Optimization to avoid double retransmission due to SACK recovery
* and when tp->snd_nxt points to already retransmitted segments
*/
if (SEQ_LT(tp->snd_nxt, tp->snd_max) && SEQ_LEQ(tp->snd_nxt, p->rxmit) &&
(uint32_t)len <= max_len) {
sendalot = 0;
}
tcpstat.tcps_sack_rexmits++;
tcpstat.tcps_sack_rexmit_bytes +=
min(len, tp->t_maxseg);
} else {
len = 0;
}
}
}
after_sack_rexmit:
/*
* Get standard flags, and add SYN or FIN if requested by 'hidden'
* state flags.
*/
if (tp->t_flags & TF_NEEDFIN) {
flags |= TH_FIN;
}
/*
* If in persist timeout with window of 0, send 1 byte.
* Otherwise, if window is small but nonzero
* and timer expired, we will send what we can
* and go to transmit state.
*/
if (tp->t_flagsext & TF_FORCE) {
if (sendwin == 0) {
/*
* If we still have some data to send, then
* clear the FIN bit. Usually this would
* happen below when it realizes that we
* aren't sending all the data. However,
* if we have exactly 1 byte of unsent data,
* then it won't clear the FIN bit below,
* and if we are in persist state, we wind
* up sending the packet without recording
* that we sent the FIN bit.
*
* We can't just blindly clear the FIN bit,
* because if we don't have any more data
* to send then the probe will be the FIN
* itself.
*/
if (off < so->so_snd.sb_cc) {
flags &= ~TH_FIN;
}
sendwin = 1;
} else {
tp->t_timer[TCPT_PERSIST] = 0;
tp->t_persist_stop = 0;
TCP_RESET_REXMT_STATE(tp);
}
}
/*
* If snd_nxt == snd_max and we have transmitted a FIN, the
* offset will be > 0 even if so_snd.sb_cc is 0, resulting in
* a negative length. This can also occur when TCP opens up
* its congestion window while receiving additional duplicate
* acks after fast-retransmit because TCP will reset snd_nxt
* to snd_max after the fast-retransmit.
*
* In the normal retransmit-FIN-only case, however, snd_nxt will
* be set to snd_una, the offset will be 0, and the length may
* wind up 0.
*
* If sack_rxmit or rack_rxmit is true we are retransmitting from
* the scoreboard in which case len is already set.
*/
bool rack_in_recovery = TCP_RACK_ENABLED(tp) && IN_FASTRECOVERY(tp);
if (rack_sack_rxmit == 0) {
if (sack_bytes_rxmt == 0 && !rack_in_recovery) {
len = min(so->so_snd.sb_cc, sendwin) - off;
} else {
int32_t cwin = tp->snd_cwnd - tcp_flight_size(tp);
if (cwin < 0) {
cwin = 0;
}
/*
* We are inside of a SACK recovery episode and are
* sending new data, having retransmitted all the
* data possible in the scoreboard.
*/
len = min(so->so_snd.sb_cc, tp->snd_wnd) - off;
/*
* Don't remove this (len > 0) check !
* We explicitly check for len > 0 here (although it
* isn't really necessary), to work around a gcc
* optimization issue - to force gcc to compute
* len above. Without this check, the computation
* of len is bungled by the optimizer.
*/
if (len > 0) {
len = imin(len, cwin);
} else {
len = 0;
}
/*
* At this point SACK recovery can not send any
* data from scoreboard or any new data. Check
* if we can do a rescue retransmit towards the
* tail end of recovery window.
* We don't do rescue retransmit for RACK.
*/
if (len == 0 && cwin > 0 &&
SEQ_LT(tp->snd_fack, tp->snd_recover) &&
!(tp->t_flagsext & TF_RESCUE_RXT) && !TCP_RACK_ENABLED(tp)) {
len = min((tp->snd_recover - tp->snd_fack),
tp->t_maxseg);
len = imin(len, cwin);
old_snd_nxt = tp->snd_nxt;
sack_rescue_rxt = TRUE;
tp->snd_nxt = tp->snd_recover - len;
/*
* If FIN has been sent, snd_max
* must have been advanced to cover it.
*/
if ((tp->t_flags & TF_SENTFIN) &&
tp->snd_max == tp->snd_recover) {
tp->snd_nxt--;
}
off = tp->snd_nxt - tp->snd_una;
sendalot = 0;
tp->t_flagsext |= TF_RESCUE_RXT;
}
}
}
if (max_len != 0 && len > 0) {
len = min(len, max_len);
}
/*
* Lop off SYN bit if it has already been sent. However, if this
* is SYN-SENT state and if segment contains data and if we don't
* know that foreign host supports TAO, suppress sending segment.
*/
if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una)) {
if (tp->t_state == TCPS_SYN_RECEIVED && TFO_ENABLED(tp) && tp->snd_nxt == tp->snd_una + 1) {
/* We are sending the SYN again! */
off--;
len++;
} else {
if (tp->t_state != TCPS_SYN_RECEIVED || TFO_ENABLED(tp)) {
flags &= ~TH_SYN;
}
off--;
len++;
if (len > 0 && tp->t_state == TCPS_SYN_SENT) {
while (inp->inp_sndinprog_cnt == 0 &&
tp->t_pktlist_head != NULL) {
packetlist = tp->t_pktlist_head;
packchain_listadd = tp->t_lastchain;
packchain_sent++;
TCP_PKTLIST_CLEAR(tp);
error = tcp_ip_output(so, tp, packetlist,
packchain_listadd, tp_inp_options,
(so_options & SO_DONTROUTE),
(rack_sack_rxmit || (sack_bytes_rxmt != 0)),
isipv6);
}
/*
* tcp was closed while we were in ip,
* resume close
*/
if (inp->inp_sndinprog_cnt == 0 &&
(tp->t_flags & TF_CLOSING)) {
tp->t_flags &= ~TF_CLOSING;
(void) tcp_close(tp);
} else {
tcp_check_timer_state(tp);
}
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_END,
0, 0, 0, 0, 0);
return 0;
}
}
}
/*
* Be careful not to send data and/or FIN on SYN segments.
* This measure is needed to prevent interoperability problems
* with not fully conformant TCP implementations.
*
* In case of TFO, we handle the setting of the len in
* tcp_tfo_check. In case TFO is not enabled, never ever send
* SYN+data.
*/
if ((flags & TH_SYN) && !TFO_ENABLED(tp)) {
len = 0;
flags &= ~TH_FIN;
}
/*
* Don't send a RST with data.
*/
if (flags & TH_RST) {
len = 0;
}
if ((flags & TH_SYN) && tp->t_state <= TCPS_SYN_SENT && TFO_ENABLED(tp)) {
len = tcp_tfo_check(tp, len);
}
/*
* The check here used to be (len < 0). Some times len is zero
* when the congestion window is closed and we need to check
* if persist timer has to be set in that case. But don't set
* persist until connection is established.
*/
if (len <= 0 && !(flags & TH_SYN)) {
/*
* If FIN has been sent but not acked,
* but we haven't been called to retransmit,
* len will be < 0. Otherwise, window shrank
* after we sent into it. If window shrank to 0,
* cancel pending retransmit, pull snd_nxt back
* to (closed) window, and set the persist timer
* if it isn't already going. If the window didn't
* close completely, just wait for an ACK.
*/
len = 0;
if (sendwin == 0) {
tp->t_timer[TCPT_REXMT] = 0;
tp->t_timer[TCPT_PTO] = 0;
TCP_RESET_REXMT_STATE(tp);
tp->snd_nxt = tp->snd_una;
off = 0;
if (tp->t_timer[TCPT_PERSIST] == 0) {
tcp_setpersist(tp);
}
}
}
/*
* Automatic sizing of send socket buffer. Increase the send
* socket buffer size if all of the following criteria are met
* 1. the receiver has enough buffer space for this data
* 2. send buffer is filled to 7/8th with data (so we actually
* have data to make use of it);
* 3. our send window (slow start and congestion controlled) is
* larger than sent but unacknowledged data in send buffer.
*/
if (!INP_WAIT_FOR_IF_FEEDBACK(inp) && !IN_FASTRECOVERY(tp) &&
(so->so_snd.sb_flags & (SB_AUTOSIZE | SB_TRIM)) == SB_AUTOSIZE) {
if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat &&
so->so_snd.sb_cc >= (so->so_snd.sb_hiwat / 8 * 7) &&
sendwin >= (so->so_snd.sb_cc - (tp->snd_nxt - tp->snd_una))) {
if (sbreserve(&so->so_snd,
min(so->so_snd.sb_hiwat + tcp_autosndbuf_inc,
tcp_autosndbuf_max)) == 1) {
so->so_snd.sb_idealsize = so->so_snd.sb_hiwat;
}
}
}
/*
* Truncate to the maximum segment length or enable TCP Segmentation
* Offloading (if supported by hardware) and ensure that FIN is removed
* if the length no longer contains the last data byte.
*
* TSO may only be used if we are in a pure bulk sending state.
* The presence of TCP-MD5, SACK retransmits, SACK advertizements,
* filters and IP options, as well as disabling hardware checksum
* offload prevent using TSO. With TSO the TCP header is the same
* (except for the sequence number) for all generated packets. This
* makes it impossible to transmit any options which vary per generated
* segment or packet.
*
* The length of TSO bursts is limited to TCP_MAXWIN. That limit and
* removal of FIN (if not already catched here) are handled later after
* the exact length of the TCP options are known.
*/
#if IPSEC
/*
* Pre-calculate here as we save another lookup into the darknesses
* of IPsec that way and can actually decide if TSO is ok.
*/
if (ipsec_bypass == 0) {
ipsec_optlen = ipsec_hdrsiz_tcp(tp);
}
#endif
if (len > tp->t_maxseg) {
if ((tp->t_flags & TF_TSO) && tcp_do_tso && hwcksum_tx &&
kipf_count == 0 &&
tp->rcv_numsacks == 0 && rack_sack_rxmit == 0 &&
sack_bytes_rxmt == 0 &&
inp->inp_options == NULL &&
inp->in6p_options == NULL
#if IPSEC
&& ipsec_optlen == 0
#endif
) {
tso = 1;
sendalot = 0;
} else {
len = tp->t_maxseg;
sendalot = 1;
tso = 0;
}
} else {
tso = 0;
}
/* Send one segment or less as a tail loss probe */
if (tp->t_flagsext & TF_SENT_TLPROBE) {
len = min(len, tp->t_maxseg);
sendalot = 0;
tso = 0;
}
#if MPTCP
if (so->so_flags & SOF_MP_SUBFLOW && off < 0) {
os_log_error(mptcp_log_handle, "%s - %lx: offset is negative! len %d off %d\n",
__func__, (unsigned long)VM_KERNEL_ADDRPERM(tp->t_mpsub->mpts_mpte),
len, off);
}
if ((so->so_flags & SOF_MP_SUBFLOW) &&
!(tp->t_mpflags & TMPF_TCP_FALLBACK)) {
int newlen = len;
struct mptcb *mp_tp = tptomptp(tp);
if (tp->t_state >= TCPS_ESTABLISHED &&
(tp->t_mpflags & TMPF_SND_MPPRIO ||
tp->t_mpflags & TMPF_SND_REM_ADDR ||
tp->t_mpflags & TMPF_SND_MPFAIL ||
(tp->t_mpflags & TMPF_SND_KEYS &&
mp_tp->mpt_version == MPTCP_VERSION_0) ||
tp->t_mpflags & TMPF_SND_JACK ||
tp->t_mpflags & TMPF_MPTCP_ECHO_ADDR)) {
if (len > 0) {
len = 0;
tso = 0;
}
/*
* On a new subflow, don't try to send again, because
* we are still waiting for the fourth ack.
*/
if (!(tp->t_mpflags & TMPF_PREESTABLISHED)) {
sendalot = 1;
}
mptcp_acknow = TRUE;
} else {
mptcp_acknow = FALSE;
}
/*
* The contiguous bytes in the subflow socket buffer can be
* discontiguous at the MPTCP level. Since only one DSS
* option can be sent in one packet, reduce length to match
* the contiguous MPTCP level. Set sendalot to send remainder.
*/
if (len > 0 && off >= 0) {
newlen = mptcp_adj_sendlen(so, off);
}
if (newlen < len) {
len = newlen;
if (len <= tp->t_maxseg) {
tso = 0;
}
}
}
#endif /* MPTCP */
if (rack_sack_rxmit) {
if (TCP_RACK_ENABLED(tp)) {
if (SEQ_LT(seg->start_seq + len, tp->snd_una + so->so_snd.sb_cc)) {
flags &= ~TH_FIN;
}
} else {
if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) {
flags &= ~TH_FIN;
}
}
} else {
if (SEQ_LT(tp->snd_nxt + len, tp->snd_una + so->so_snd.sb_cc)) {
flags &= ~TH_FIN;
}
}
/*
* Compare available window to amount of window
* known to peer (as advertised window less
* next expected input). If the difference is at least two
* max size segments, or at least 25% of the maximum possible
* window, then want to send a window update to peer.
*/
recwin = tcp_sbspace(tp);
if (!(so->so_flags & SOF_MP_SUBFLOW)) {
if (recwin < (int32_t)(so->so_rcv.sb_hiwat / 4) &&
recwin < (int)tp->t_maxseg) {
recwin = 0;
}
} else {
struct mptcb *mp_tp = tptomptp(tp);
struct socket *mp_so = mptetoso(mp_tp->mpt_mpte);
if (recwin < (int32_t)(mp_so->so_rcv.sb_hiwat / 4) &&
recwin < (int)tp->t_maxseg) {
recwin = 0;
}
}
#if TRAFFIC_MGT
if (tcp_recv_bg == 1 || IS_TCP_RECV_BG(so)) {
/*
* Timestamp MUST be supported to use rledbat unless we haven't
* yet negotiated it.
*/
if (TCP_RLEDBAT_ENABLED(tp) || (tcp_rledbat && tp->t_state <
TCPS_ESTABLISHED)) {
if (recwin > 0 && tcp_cc_rledbat.get_rlwin != NULL) {
/* Min of flow control window and rledbat window */
recwin = imin(recwin, tcp_cc_rledbat.get_rlwin(tp));
}
} else if (recwin > 0 && tcp_recv_throttle(tp)) {
uint32_t min_iaj_win = tcp_min_iaj_win * tp->t_maxseg;
uint32_t bg_rwintop = tp->rcv_adv;
if (SEQ_LT(bg_rwintop, tp->rcv_nxt + min_iaj_win)) {
bg_rwintop = tp->rcv_nxt + min_iaj_win;
}
recwin = imin((int32_t)(bg_rwintop - tp->rcv_nxt),
recwin);
if (recwin < 0) {
recwin = 0;
}
}
}
#endif /* TRAFFIC_MGT */
if (recwin > (int32_t)(TCP_MAXWIN << tp->rcv_scale)) {
recwin = (int32_t)(TCP_MAXWIN << tp->rcv_scale);
}
if (!(so->so_flags & SOF_MP_SUBFLOW)) {
if (recwin < (int32_t)(tp->rcv_adv - tp->rcv_nxt)) {
recwin = (int32_t)(tp->rcv_adv - tp->rcv_nxt);
}
} else {
struct mptcb *mp_tp = tptomptp(tp);
int64_t recwin_announced = (int64_t)(mp_tp->mpt_rcvadv - mp_tp->mpt_rcvnxt);
/* Don't remove what we announced at the MPTCP-layer */
VERIFY(recwin_announced < INT32_MAX && recwin_announced > INT32_MIN);
if (recwin < (int32_t)recwin_announced) {
recwin = (int32_t)recwin_announced;
}
}
/*
* Sender silly window avoidance. We transmit under the following
* conditions when len is non-zero:
*
* - we've timed out (e.g. persist timer)
* - we need to retransmit
* - We have a full segment (or more with TSO)
* - This is the last buffer in a write()/send() and we are
* either idle or running NODELAY
* - we have more then 1/2 the maximum send window's worth of
* data (receiver may be limited the window size)
*/
if (len) {
if (tp->t_flagsext & TF_FORCE) {
goto send;
}
if (SEQ_LT(tp->snd_nxt, tp->snd_max)) {
if (TCP_RACK_ENABLED(tp) && rack_sack_rxmit == 0) {
len = min(len, tp->snd_max - tp->snd_nxt);
}
goto send;
}
if (rack_sack_rxmit) {
goto send;
}
/*
* If this here is the first segment after SYN/ACK and TFO
* is being used, then we always send it, regardless of Nagle,...
*/
if (tp->t_state == TCPS_SYN_RECEIVED &&
TFO_ENABLED(tp) &&
(tp->t_tfo_flags & TFO_F_COOKIE_VALID) &&
tp->snd_nxt == tp->iss + 1) {
goto send;
}
/*
* Send new data on the connection only if it is
* not flow controlled
*/
if (!INP_WAIT_FOR_IF_FEEDBACK(inp) ||
tp->t_state != TCPS_ESTABLISHED) {
if (off + len == tp->snd_wnd) {
/* We are limited by the receiver's window... */
if (tp->t_rcvwnd_limited_start_time == 0) {
tp->t_rcvwnd_limited_start_time = net_uptime_us();
}
} else {
/* We are no more limited by the receiver's window... */
if (tp->t_rcvwnd_limited_start_time != 0) {
uint64_t now = net_uptime_us();
ASSERT(now >= tp->t_rcvwnd_limited_start_time);
tp->t_rcvwnd_limited_total_time += (now - tp->t_rcvwnd_limited_start_time);
tp->t_rcvwnd_limited_start_time = 0;
}
}
if (len >= tp->t_maxseg) {
goto send;
}
if (!(tp->t_flags & TF_MORETOCOME) &&
(idle || tp->t_flags & TF_NODELAY ||
(tp->t_flags & TF_MAXSEGSNT) ||
ALLOW_LIMITED_TRANSMIT(tp)) &&
(tp->t_flags & TF_NOPUSH) == 0 &&
(len + off >= so->so_snd.sb_cc ||
/*
* MPTCP needs to respect the DSS-mappings. So, it
* may be sending data that *could* have been
* coalesced, but cannot because of
* mptcp_adj_sendlen().
*/
so->so_flags & SOF_MP_SUBFLOW)) {
goto send;
}
if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) {
goto send;
}
} else {
tcpstat.tcps_fcholdpacket++;
}
}
if (recwin > 0) {
/*
* "adv" is the amount we can increase the window,
* taking into account that we are limited by
* TCP_MAXWIN << tp->rcv_scale.
*/
int32_t adv, oldwin = 0;
adv = imin(recwin, (int)TCP_MAXWIN << tp->rcv_scale) -
(tp->rcv_adv - tp->rcv_nxt);
if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) {
oldwin = tp->rcv_adv - tp->rcv_nxt;
}
if (tcp_ack_strategy == TCP_ACK_STRATEGY_LEGACY) {
if (adv >= (int32_t) (2 * tp->t_maxseg)) {
/*
* Update only if the resulting scaled value of
* the window changed, or if there is a change in
* the sequence since the last ack. This avoids
* what appears as dupe ACKS (see rdar://5640997)
*
* If streaming is detected avoid sending too many
* window updates. We will depend on the delack
* timer to send a window update when needed.
*
* If there is more data to read, don't send an ACK.
* Otherwise we will end up sending many ACKs if the
* application is doing micro-reads.
*/
if (!(tp->t_flags & TF_STRETCHACK) &&
(tp->last_ack_sent != tp->rcv_nxt ||
((oldwin + adv) >> tp->rcv_scale) >
(oldwin >> tp->rcv_scale))) {
goto send;
}
}
} else {
if (adv >= (int32_t) (2 * tp->t_maxseg)) {
/*
* ACK every second full-sized segment, if the
* ACK is advancing or the window becomes bigger
*/
if (so->so_rcv.sb_cc < so->so_rcv.sb_lowat &&
(tp->last_ack_sent != tp->rcv_nxt ||
((oldwin + adv) >> tp->rcv_scale) >
(oldwin >> tp->rcv_scale))) {
goto send;
}
} else if (tp->t_flags & TF_DELACK) {
/*
* If we delayed the ACK and the window
* is not advancing by a lot (< 2MSS), ACK
* immediately if the last incoming packet had
* the push flag set and we emptied the buffer.
*
* This takes care of a sender doing small
* repeated writes with Nagle enabled.
*/
if (so->so_rcv.sb_cc == 0 &&
tp->last_ack_sent != tp->rcv_nxt &&
(tp->t_flagsext & TF_LAST_IS_PSH)) {
goto send;
}
}
}
if (4 * adv >= (int32_t) so->so_rcv.sb_hiwat) {
goto send;
}
/*
* Make sure that the delayed ack timer is set if
* we delayed sending a window update because of
* streaming detection.
*/
if (tcp_ack_strategy == TCP_ACK_STRATEGY_LEGACY &&
(tp->t_flags & TF_STRETCHACK) &&
!(tp->t_flags & TF_DELACK)) {
tp->t_flags |= TF_DELACK;
tp->t_timer[TCPT_DELACK] =
OFFSET_FROM_START(tp, tcp_delack);
}
}
/*
* Send if we owe the peer an ACK, RST, SYN, or urgent data. ACKNOW
* is also a catch-all for the retransmit timer timeout case.
*/
if (tp->t_flags & TF_ACKNOW) {
if (tp->t_forced_acks > 0) {
tp->t_forced_acks--;
}
goto send;
}
if ((flags & TH_RST) || (flags & TH_SYN)) {
goto send;
}
if (SEQ_GT(tp->snd_up, tp->snd_una)) {
goto send;
}
#if MPTCP
if (mptcp_acknow) {
goto send;
}
#endif /* MPTCP */
/*
* If our state indicates that FIN should be sent
* and we have not yet done so, then we need to send.
*/
if ((flags & TH_FIN) &&
(!(tp->t_flags & TF_SENTFIN) || tp->snd_nxt == tp->snd_una)) {
goto send;
}
/*
* In SACK, it is possible for tcp_output to fail to send a segment
* after the retransmission timer has been turned off. Make sure
* that the retransmission timer is set.
*/
if (SACK_ENABLED(tp) && (tp->t_state >= TCPS_ESTABLISHED) &&
SEQ_GT(tp->snd_max, tp->snd_una) &&
tp->t_timer[TCPT_REXMT] == 0 &&
tp->t_timer[TCPT_PERSIST] == 0) {
tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp,
tp->t_rxtcur);
goto just_return;
}
/*
* TCP window updates are not reliable, rather a polling protocol
* using ``persist'' packets is used to insure receipt of window
* updates. The three ``states'' for the output side are:
* idle not doing retransmits or persists
* persisting to move a small or zero window
* (re)transmitting and thereby not persisting
*
* tp->t_timer[TCPT_PERSIST]
* is set when we are in persist state.
* tp->t_force
* is set when we are called to send a persist packet.
* tp->t_timer[TCPT_REXMT]
* is set when we are retransmitting
* The output side is idle when both timers are zero.
*
* If send window is too small, there is data to transmit, and no
* retransmit or persist is pending, then go to persist state.
* If nothing happens soon, send when timer expires:
* if window is nonzero, transmit what we can,
* otherwise force out a byte.
*/
if (so->so_snd.sb_cc && tp->t_timer[TCPT_REXMT] == 0 &&
tp->t_timer[TCPT_PERSIST] == 0) {
TCP_RESET_REXMT_STATE(tp);
tcp_setpersist(tp);
}
just_return:
/*
* If there is no reason to send a segment, just return.
* but if there is some packets left in the packet list, send them now.
*/
while (inp->inp_sndinprog_cnt == 0 &&
tp->t_pktlist_head != NULL) {
packetlist = tp->t_pktlist_head;
packchain_listadd = tp->t_lastchain;
packchain_sent++;
TCP_PKTLIST_CLEAR(tp);
error = tcp_ip_output(so, tp, packetlist,
packchain_listadd,
tp_inp_options, (so_options & SO_DONTROUTE),
(rack_sack_rxmit || (sack_bytes_rxmt != 0)), isipv6);
}
/* tcp was closed while we were in ip; resume close */
if (inp->inp_sndinprog_cnt == 0 &&
(tp->t_flags & TF_CLOSING)) {
tp->t_flags &= ~TF_CLOSING;
(void) tcp_close(tp);
} else {
tcp_check_timer_state(tp);
}
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
return 0;
send:
/*
* Set TF_MAXSEGSNT flag if the segment size is greater than
* the max segment size.
*/
if (len > 0) {
do_not_compress = TRUE;
if (len >= tp->t_maxseg) {
tp->t_flags |= TF_MAXSEGSNT;
} else {
tp->t_flags &= ~TF_MAXSEGSNT;
}
}
/*
* If we are connected and no segment has been ACKed or SACKed yet and we
* hit a retransmission timeout, then we should disable AccECN option
* for the rest of the connection.
*/
if (TCP_ACC_ECN_ON(tp) && tp->t_state == TCPS_ESTABLISHED &&
tp->snd_una == tp->iss + 1 && (tp->snd_fack == tp->iss)
&& tp->t_rxtshift > 0) {
if ((tp->ecn_flags & TE_RETRY_WITHOUT_ACO) == 0) {
tp->ecn_flags |= TE_RETRY_WITHOUT_ACO;
}
}
/*
* Before ESTABLISHED, force sending of initial options
* unless TCP set not to do any options.
* NOTE: we assume that the IP/TCP header plus TCP options
* always fit in a single mbuf, leaving room for a maximum
* link header, i.e.
* max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES
*/
optlen = 0;
if (isipv6) {
hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
} else {
hdrlen = sizeof(struct tcpiphdr);
}
if (flags & TH_SYN) {
tp->snd_nxt = tp->iss;
tp->snd_fack = tp->iss;
if ((tp->t_flags & TF_NOOPT) == 0) {
u_short mss;
opt[0] = TCPOPT_MAXSEG;
opt[1] = TCPOLEN_MAXSEG;
mss = htons((u_short) tcp_mssopt(tp));
(void)memcpy(opt + 2, &mss, sizeof(mss));
optlen = TCPOLEN_MAXSEG;
if ((tp->t_flags & TF_REQ_SCALE) &&
((flags & TH_ACK) == 0 ||
(tp->t_flags & TF_RCVD_SCALE))) {
*((u_int32_t *)(void *)(opt + optlen)) = htonl(
TCPOPT_NOP << 24 |
TCPOPT_WINDOW << 16 |
TCPOLEN_WINDOW << 8 |
tp->request_r_scale);
optlen += 4;
}
#if MPTCP
if (mptcp_enable && (so->so_flags & SOF_MP_SUBFLOW)) {
optlen = mptcp_setup_syn_opts(so, opt, optlen);
}
#endif /* MPTCP */
}
}
/*
* Send a timestamp and echo-reply if this is a SYN and our side
* wants to use timestamps (TF_REQ_TSTMP is set) or both our side
* and our peer have sent timestamps in our SYN's.
*/
if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP &&
(flags & TH_RST) == 0 &&
((flags & TH_ACK) == 0 ||
(tp->t_flags & TF_RCVD_TSTMP))) {
u_int32_t *lp = (u_int32_t *)(void *)(opt + optlen);
/* Form timestamp option as shown in appendix A of RFC 1323. */
*lp++ = htonl(TCPOPT_TSTAMP_HDR);
*lp++ = htonl(tcp_now_local + tp->t_ts_offset);
*lp = htonl(tp->ts_recent);
optlen += TCPOLEN_TSTAMP_APPA;
}
if (SACK_ENABLED(tp) && ((tp->t_flags & TF_NOOPT) == 0)) {
/*
* Tack on the SACK permitted option *last*.
* And do padding of options after tacking this on.
* This is because of MSS, TS, WinScale and Signatures are
* all present, we have just 2 bytes left for the SACK
* permitted option, which is just enough.
*/
/*
* If this is the first SYN of connection (not a SYN
* ACK), include SACK permitted option. If this is a
* SYN ACK, include SACK permitted option if peer has
* already done so. This is only for active connect,
* since the syncache takes care of the passive connect.
*/
if ((flags & TH_SYN) &&
(!(flags & TH_ACK) || (tp->t_flags & TF_SACK_PERMIT))) {
u_char *bp;
bp = (u_char *)opt + optlen;
*bp++ = TCPOPT_SACK_PERMITTED;
*bp++ = TCPOLEN_SACK_PERMITTED;
optlen += TCPOLEN_SACK_PERMITTED;
}
}
#if MPTCP
if (so->so_flags & SOF_MP_SUBFLOW) {
/*
* Its important to piggyback acks with data as ack only packets
* may get lost and data packets that don't send Data ACKs
* still advance the subflow level ACK and therefore make it
* hard for the remote end to recover in low cwnd situations.
*/
if (len != 0) {
tp->t_mpflags |= (TMPF_SEND_DSN |
TMPF_MPTCP_ACKNOW);
} else {
tp->t_mpflags |= TMPF_MPTCP_ACKNOW;
}
optlen = mptcp_setup_opts(tp, off, &opt[0], optlen, flags,
len, &mptcp_acknow, &do_not_compress);
tp->t_mpflags &= ~TMPF_SEND_DSN;
}
#endif /* MPTCP */
if (TFO_ENABLED(tp) && !(tp->t_flags & TF_NOOPT) &&
(flags & (TH_SYN | TH_ACK)) == TH_SYN) {
optlen += tcp_tfo_write_cookie(tp, optlen, len, opt);
}
if (TFO_ENABLED(tp) &&
(flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK) &&
(tp->t_tfo_flags & TFO_F_OFFER_COOKIE)) {
optlen += tcp_tfo_write_cookie_rep(tp, optlen, opt);
}
if (SACK_ENABLED(tp) && ((tp->t_flags & TF_NOOPT) == 0)) {
/*
* Send SACKs if necessary. This should be the last
* option processed. Only as many SACKs are sent as
* are permitted by the maximum options size.
*
* In general, SACK blocks consume 8*n+2 bytes.
* So a full size SACK blocks option is 34 bytes
* (to generate 4 SACK blocks). At a minimum,
* we need 10 bytes (to generate 1 SACK block).
* If TCP Timestamps (12 bytes) and TCP Signatures
* (18 bytes) are both present, we'll just have
* 10 bytes for SACK options 40 - (12 + 18).
*/
if (TCPS_HAVEESTABLISHED(tp->t_state) &&
(tp->t_flags & TF_SACK_PERMIT) &&
(tp->rcv_numsacks > 0 || TCP_SEND_DSACK_OPT(tp)) &&
MAX_TCPOPTLEN - optlen >= TCPOLEN_SACK + 2) {
unsigned int sackoptlen = 0;
int nsack, padlen;
u_char *bp = (u_char *)opt + optlen;
u_int32_t *lp;
nsack = (MAX_TCPOPTLEN - optlen - 2) / TCPOLEN_SACK;
/*
* Send lesser SACK blocks when we want
* to send the smallest recommended AccECN Option
* if the space wouldn't permit sending all blocks.
*/
if (nsack > 2 && TCP_ACC_ECN_ON(tp) &&
(tp->ecn_flags & TE_RETRY_WITHOUT_ACO) == 0 &&
tp->ecn_flags & (TE_ACO_ECT1 | TE_ACO_ECT0)) {
nsack--;
}
nsack = min(nsack, (tp->rcv_numsacks +
(TCP_SEND_DSACK_OPT(tp) ? 1 : 0)));
sackoptlen = (2 + nsack * TCPOLEN_SACK);
VERIFY(sackoptlen < UINT8_MAX);
/*
* First we need to pad options so that the
* SACK blocks can start at a 4-byte boundary
* (sack option and length are at a 2 byte offset).
*/
padlen = (MAX_TCPOPTLEN - optlen - sackoptlen) % 4;
optlen += padlen;
while (padlen-- > 0) {
*bp++ = TCPOPT_NOP;
}
tcpstat.tcps_sack_send_blocks++;
*bp++ = TCPOPT_SACK;
*bp++ = (uint8_t)sackoptlen;
lp = (u_int32_t *)(void *)bp;
/*
* First block of SACK option should represent
* DSACK. Prefer to send SACK information if there
* is space for only one SACK block. This will
* allow for faster recovery.
*/
if (TCP_SEND_DSACK_OPT(tp) && nsack > 0 &&
(tp->rcv_numsacks == 0 || nsack > 1)) {
*lp++ = htonl(tp->t_dsack_lseq);
*lp++ = htonl(tp->t_dsack_rseq);
tcpstat.tcps_dsack_sent++;
tp->t_dsack_sent++;
nsack--;
}
VERIFY(nsack == 0 || tp->rcv_numsacks >= nsack);
for (i = 0; i < nsack; i++) {
struct sackblk sack = tp->sackblks[i];
*lp++ = htonl(sack.start);
*lp++ = htonl(sack.end);
}
optlen += sackoptlen;
/* Make sure we didn't write too much */
VERIFY((u_char *)lp - opt <= MAX_TCPOPTLEN);
}
}
/*
* AccECN option - after SACK
* Don't send on <SYN>,
* send only on <SYN,ACK> before ACCECN is negotiated or
* when doing an AccECN session. Don't send AccECN option
* if retransmitting a SYN-ACK or a data segment
*/
if ((TCP_ACC_ECN_ON(tp) ||
(TCP_ACC_ECN_ENABLED(tp) && (flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK)))
&& ((tp->ecn_flags & TE_RETRY_WITHOUT_ACO) == 0)) {
uint32_t *lp = (uint32_t *)(void *)(opt + optlen);
/* lp will become outdated after options are added */
tcp_add_accecn_option(tp, flags, lp, (uint8_t *)&optlen);
}
/* Pad TCP options to a 4 byte boundary */
if (optlen < MAX_TCPOPTLEN && (optlen % sizeof(u_int32_t))) {
int pad = sizeof(u_int32_t) - (optlen % sizeof(u_int32_t));
u_char *bp = (u_char *)opt + optlen;
optlen += pad;
while (pad) {
*bp++ = TCPOPT_EOL;
pad--;
}
}
/*
* For Accurate ECN, send ACE flag based on r.cep, if
* We have completed handshake and are in ESTABLISHED state, and
* This is not the final ACK of 3WHS.
*/
if (TCP_ACC_ECN_ON(tp) && TCPS_HAVEESTABLISHED(tp->t_state) &&
(tp->ecn_flags & TE_ACE_FINAL_ACK_3WHS) == 0) {
uint8_t ace = tp->t_aecn.t_rcv_ce_packets & TCP_ACE_MASK;
if (ace & 0x01) {
flags |= TH_ECE;
} else {
flags &= ~TH_ECE;
}
if (ace & 0x02) {
flags |= TH_CWR;
} else {
flags &= ~TH_CWR;
}
if (ace & 0x04) {
flags |= TH_AE;
} else {
flags &= ~TH_AE;
}
}
/*
* RFC 3168 states that:
* - If you ever sent an ECN-setup SYN/SYN-ACK you must be prepared
* to handle the TCP ECE flag, even if you also later send a
* non-ECN-setup SYN/SYN-ACK.
* - If you ever send a non-ECN-setup SYN/SYN-ACK, you must not set
* the ip ECT flag.
*
* It is not clear how the ECE flag would ever be set if you never
* set the IP ECT flag on outbound packets. All the same, we use
* the TE_SETUPSENT to indicate that we have committed to handling
* the TCP ECE flag correctly. We use the TE_SENDIPECT to indicate
* whether or not we should set the IP ECT flag on outbound packet
*
* For a SYN-ACK, send an ECN setup SYN-ACK
*
* Below we send ECN for three different handhshake states:
* 1. Server received SYN and is sending a SYN-ACK (state->TCPS_SYN_RECEIVED)
* - both classic and Accurate ECN have special encoding
* 2. Client is sending SYN packet (state->SYN_SENT)
* - both classic and Accurate ECN have special encoding
* 3. Client is sending final ACK of 3WHS (state->ESTABLISHED)
* - Only Accurate ECN has special encoding
*/
if ((flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK) &&
(tp->ecn_flags & TE_ENABLE_ECN)) {
/* Server received either legacy or Accurate ECN setup SYN */
if (tp->ecn_flags & (TE_SETUPRECEIVED | TE_ACE_SETUPRECEIVED)) {
if (tcp_send_ecn_flags_on_syn(tp)) {
if (TCP_ACC_ECN_ENABLED(tp) && (tp->ecn_flags & TE_ACE_SETUPRECEIVED)) {
/*
* Accurate ECN mode is on. Initialize packet and byte counters
* for the server sending SYN-ACK. Although s_cep will be initialized
* during input processing of ACK of SYN-ACK, initialize here as well
* in case ACK gets lost.
*
* Non-zero initial values are used to
* support a stateless handshake (see
* Section 5.1 of AccECN draft) and to be
* distinct from cases where the fields
* are incorrectly zeroed.
*/
tp->t_aecn.t_rcv_ce_packets = 5;
tp->t_aecn.t_snd_ce_packets = 5;
/* Initialize CE byte counter to 0 */
tp->t_aecn.t_rcv_ce_bytes = tp->t_aecn.t_snd_ce_bytes = 0;
if (tp->ecn_flags & TE_ACE_SETUP_NON_ECT) {
tp->t_prev_ace_flags = TH_CWR;
flags |= tp->t_prev_ace_flags;
/* Remove the setup flag as it is also used for final ACK */
tp->ecn_flags &= ~TE_ACE_SETUP_NON_ECT;
tcpstat.tcps_ecn_ace_syn_not_ect++;
} else if (tp->ecn_flags & TE_ACE_SETUP_ECT1) {
tp->t_prev_ace_flags = (TH_CWR | TH_ECE);
flags |= tp->t_prev_ace_flags;
tp->ecn_flags &= ~TE_ACE_SETUP_ECT1;
tcpstat.tcps_ecn_ace_syn_ect1++;
} else if (tp->ecn_flags & TE_ACE_SETUP_ECT0) {
tp->t_prev_ace_flags = TH_AE;
flags |= tp->t_prev_ace_flags;
tp->ecn_flags &= ~TE_ACE_SETUP_ECT0;
tcpstat.tcps_ecn_ace_syn_ect0++;
} else if (tp->ecn_flags & TE_ACE_SETUP_CE) {
tp->t_prev_ace_flags = (TH_AE | TH_CWR);
flags |= tp->t_prev_ace_flags;
tp->ecn_flags &= ~TE_ACE_SETUP_CE;
/*
* Receive counter is updated on
* all acceptable packets except
* CE on SYN packets (SYN=1, ACK=0)
*/
tcpstat.tcps_ecn_ace_syn_ce++;
} else {
if (tp->t_prev_ace_flags != 0) {
/* Set the flags for retransmitted SYN-ACK same as the previous one */
flags |= tp->t_prev_ace_flags;
} else {
/* We shouldn't come here */
panic("ECN flags (0x%x) not set correctly", tp->ecn_flags);
}
}
/*
* We now send ECT1 packets when
* L4S and Accurate ECN mode is on
*/
tp->ecn_flags |= TE_ACE_SETUPSENT;
if (TCP_L4S_ENABLED(tp)) {
tp->ecn_flags |= TE_SENDIPECT;
}
} else if (tp->ecn_flags & TE_SETUPRECEIVED) {
/*
* Setting TH_ECE makes this an ECN-setup
* SYN-ACK
*/
flags |= TH_ECE;
/*
* Record that we sent the ECN-setup and
* default to setting IP ECT.
*/
tp->ecn_flags |= (TE_SETUPSENT | TE_SENDIPECT);
}
tcpstat.tcps_ecn_server_setup++;
tcpstat.tcps_ecn_server_success++;
} else {
/*
* For classic ECN, we sent an ECN-setup SYN-ACK but it was
* dropped. Fallback to non-ECN-setup
* SYN-ACK and clear flag to indicate that
* we should not send data with IP ECT set
*
* Pretend we didn't receive an
* ECN-setup SYN.
*
* We already incremented the counter
* assuming that the ECN setup will
* succeed. Decrementing here
* tcps_ecn_server_success to correct it.
*
* For Accurate ECN, we don't yet remove TE_ACE_SETUPRECEIVED
* as the client might have received Accurate ECN SYN-ACK.
* We decide Accurate ECN's state on processing last ACK from the client.
*/
if (tp->ecn_flags & (TE_SETUPSENT | TE_ACE_SETUPSENT)) {
tcpstat.tcps_ecn_lost_synack++;
tcpstat.tcps_ecn_server_success--;
tp->ecn_flags |= TE_LOST_SYNACK;
}
if (!TCP_ACC_ECN_ENABLED(tp)) {
/* Do this only for classic ECN. */
tp->ecn_flags &=
~(TE_SETUPRECEIVED | TE_SENDIPECT |
TE_SENDCWR);
}
}
}
} else if ((flags & (TH_SYN | TH_ACK)) == TH_SYN &&
(tp->ecn_flags & TE_ENABLE_ECN)) {
if (tcp_send_ecn_flags_on_syn(tp)) {
if (TCP_ACC_ECN_ENABLED(tp)) {
/*
* We are negotiating AccECN in SYN.
* We only set TE_SENDIPECT after the handshake
* is complete.
*/
flags |= TH_ACE;
tp->ecn_flags |= (TE_ACE_SETUPSENT);
} else {
/*
* Setting TH_ECE and TH_CWR makes this an
* ECN-setup SYN
*/
flags |= (TH_ECE | TH_CWR);
/*
* Record that we sent the ECN-setup and default to
* setting IP ECT.
*/
tp->ecn_flags |= (TE_SETUPSENT | TE_SENDIPECT);
}
tcpstat.tcps_ecn_client_setup++;
tp->ecn_flags |= TE_CLIENT_SETUP;
} else {
/*
* We sent an ECN-setup SYN but it was dropped.
* Fall back to non-ECN and clear flag indicating
* we should send data with IP ECT set.
*/
if (tp->ecn_flags & (TE_SETUPSENT | TE_ACE_SETUPSENT)) {
tcpstat.tcps_ecn_lost_syn++;
tp->ecn_flags |= TE_LOST_SYN;
}
tp->ecn_flags &= ~TE_SENDIPECT;
}
} else if (TCP_ACC_ECN_ON(tp) && (tp->ecn_flags & TE_ACE_FINAL_ACK_3WHS) &&
len == 0 && (flags & (TH_FLAGS_ALL)) == TH_ACK) {
/*
* Client has processed SYN-ACK and moved to ESTABLISHED.
* This is the final ACK of 3WHS. If ACC_ECN has been negotiated,
* then send the handshake encoding as per Table 3 of Accurate ECN draft.
* We are clearing the ACE flags just in case if they were set before.
* TODO: if client has to carry data in the 3WHS ACK, then we need to send a pure ACK first
*/
flags &= ~(TH_AE | TH_CWR | TH_ECE);
if (tp->ecn_flags & TE_ACE_SETUP_NON_ECT) {
flags |= TH_CWR;
tp->ecn_flags &= ~TE_ACE_SETUP_NON_ECT;
} else if (tp->ecn_flags & TE_ACE_SETUP_ECT1) {
flags |= (TH_CWR | TH_ECE);
tp->ecn_flags &= ~TE_ACE_SETUP_ECT1;
} else if (tp->ecn_flags & TE_ACE_SETUP_ECT0) {
flags |= TH_AE;
tp->ecn_flags &= ~TE_ACE_SETUP_ECT0;
} else if (tp->ecn_flags & TE_ACE_SETUP_CE) {
flags |= (TH_AE | TH_CWR);
tp->ecn_flags &= ~TE_ACE_SETUP_CE;
}
tp->ecn_flags &= ~(TE_ACE_FINAL_ACK_3WHS);
}
/*
* Check if we should set the TCP CWR flag.
* CWR flag is sent when we reduced the congestion window because
* we received a TCP ECE or we performed a fast retransmit. We
* never set the CWR flag on retransmitted packets. We only set
* the CWR flag on data packets. Pure acks don't have this set.
*/
if ((tp->ecn_flags & TE_SENDCWR) != 0 && len != 0 &&
!SEQ_LT(tp->snd_nxt, tp->snd_max) && !rack_sack_rxmit) {
flags |= TH_CWR;
tp->ecn_flags &= ~TE_SENDCWR;
}
/*
* Check if we should set the TCP ECE flag.
*/
if ((tp->ecn_flags & TE_SENDECE) != 0 && len == 0) {
flags |= TH_ECE;
tcpstat.tcps_ecn_sent_ece++;
}
hdrlen += optlen;
/* Reset DSACK sequence numbers */
tp->t_dsack_lseq = 0;
tp->t_dsack_rseq = 0;
if (isipv6) {
ipoptlen = ip6_optlen(inp);
} else {
if (tp_inp_options) {
ipoptlen = tp_inp_options->m_len -
offsetof(struct ipoption, ipopt_list);
} else {
ipoptlen = 0;
}
}
#if IPSEC
ipoptlen += ipsec_optlen;
#endif
/*
* Adjust data length if insertion of options will
* bump the packet length beyond the t_maxopd length.
* Clear the FIN bit because we cut off the tail of
* the segment.
*
* When doing TSO limit a burst to TCP_MAXWIN minus the
* IP, TCP and Options length to keep ip->ip_len from
* overflowing. Prevent the last segment from being
* fractional thus making them all equal sized and set
* the flag to continue sending. TSO is disabled when
* IP options or IPSEC are present.
*/
if (len + optlen + ipoptlen > tp->t_maxopd) {
/*
* If there is still more to send,
* don't close the connection.
*/
flags &= ~TH_FIN;
if (tso) {
int32_t tso_maxlen;
tso_maxlen = tp->tso_max_segment_size ?
tp->tso_max_segment_size : TCP_MAXWIN;
/* hdrlen includes optlen */
if (len > tso_maxlen - hdrlen) {
len = tso_maxlen - hdrlen;
sendalot = 1;
} else if (tp->t_flags & TF_NEEDFIN) {
sendalot = 1;
}
if (len % (tp->t_maxopd - optlen) != 0) {
len = len - (len % (tp->t_maxopd - optlen));
sendalot = 1;
}
} else {
len = tp->t_maxopd - optlen - ipoptlen;
sendalot = 1;
}
}
if (max_linkhdr + hdrlen > MCLBYTES) {
panic("tcphdr too big");
}
/* Check if there is enough data in the send socket
* buffer to start measuring bandwidth
*/
if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 &&
(tp->t_bwmeas != NULL) &&
(tp->t_flagsext & TF_BWMEAS_INPROGRESS) == 0) {
tp->t_bwmeas->bw_size = min(min(
(so->so_snd.sb_cc - (tp->snd_max - tp->snd_una)),
tp->snd_cwnd), tp->snd_wnd);
if (tp->t_bwmeas->bw_minsize > 0 &&
tp->t_bwmeas->bw_size < tp->t_bwmeas->bw_minsize) {
tp->t_bwmeas->bw_size = 0;
}
if (tp->t_bwmeas->bw_maxsize > 0) {
tp->t_bwmeas->bw_size = min(tp->t_bwmeas->bw_size,
tp->t_bwmeas->bw_maxsize);
}
if (tp->t_bwmeas->bw_size > 0) {
tp->t_flagsext |= TF_BWMEAS_INPROGRESS;
tp->t_bwmeas->bw_start = tp->snd_max;
tp->t_bwmeas->bw_ts = tcp_now_local;
}
}
VERIFY(inp->inp_flowhash != 0);
/*
* Grab a header mbuf, attaching a copy of data to
* be transmitted, and initialize the header from
* the template for sends on this connection.
*/
if (len) {
/* Remember what the last head-of-line packet-size was */
if (tp->t_pmtud_lastseg_size == 0 && tp->snd_nxt == tp->snd_una) {
ASSERT(len + optlen + ipoptlen <= IP_MAXPACKET);
tp->t_pmtud_lastseg_size = (uint16_t)(len + optlen + ipoptlen);
}
if ((tp->t_flagsext & TF_FORCE) && len == 1) {
tcpstat.tcps_sndprobe++;
} else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || rack_sack_rxmit) {
tcpstat.tcps_sndrexmitpack++;
tcpstat.tcps_sndrexmitbyte += len;
if (nstat_collect) {
nstat_route_tx(inp->inp_route.ro_rt, 1,
len, NSTAT_TX_FLAG_RETRANSMIT);
INP_ADD_STAT(inp, ifnet_count_type,
txpackets, 1);
INP_ADD_STAT(inp, ifnet_count_type,
txbytes, len);
tp->t_stat.txretransmitbytes += len;
tp->t_stat.rxmitpkts++;
}
if (tp->ecn_flags & TE_SENDIPECT) {
tp->t_ecn_capable_packets_lost++;
}
} else {
tcpstat.tcps_sndpack++;
tcpstat.tcps_sndbyte += len;
if (nstat_collect) {
INP_ADD_STAT(inp, ifnet_count_type,
txpackets, 1);
INP_ADD_STAT(inp, ifnet_count_type,
txbytes, len);
}
if (tp->ecn_flags & TE_SENDIPECT) {
tp->t_ecn_capable_packets_sent++;
}
inp_decr_sndbytes_unsent(so, len);
}
inp_set_activity_bitmap(inp);
#if MPTCP
if (tp->t_mpflags & TMPF_MPTCP_TRUE) {
tcpstat.tcps_mp_sndpacks++;
tcpstat.tcps_mp_sndbytes += len;
}
#endif /* MPTCP */
/*
* try to use the new interface that allocates all
* the necessary mbuf hdrs under 1 mbuf lock and
* avoids rescanning the socket mbuf list if
* certain conditions are met. This routine can't
* be used in the following cases...
* 1) the protocol headers exceed the capacity of
* of a single mbuf header's data area (no cluster attached)
* 2) the length of the data being transmitted plus
* the protocol headers fits into a single mbuf header's
* data area (no cluster attached)
*/
m = NULL;
/* minimum length we are going to allocate */
allocated_len = MHLEN;
if (MHLEN < hdrlen + max_linkhdr) {
MGETHDR(m, M_DONTWAIT, MT_HEADER);
if (m == NULL) {
error = ENOBUFS;
goto out;
}
MCLGET(m, M_DONTWAIT);
if ((m->m_flags & M_EXT) == 0) {
m_freem(m);
error = ENOBUFS;
goto out;
}
m->m_data += max_linkhdr;
m->m_len = hdrlen;
allocated_len = MCLBYTES;
}
if (len <= allocated_len - hdrlen - max_linkhdr) {
if (m == NULL) {
VERIFY(allocated_len <= MHLEN);
MGETHDR(m, M_DONTWAIT, MT_HEADER);
if (m == NULL) {
error = ENOBUFS;
goto out;
}
m->m_data += max_linkhdr;
m->m_len = hdrlen;
}
/* makes sure we still have data left to be sent at this point */
if (so->so_snd.sb_mb == NULL || off < 0) {
if (m != NULL) {
m_freem(m);
}
error = 0; /* should we return an error? */
goto out;
}
m_copydata(so->so_snd.sb_mb, off, (int) len,
mtod(m, caddr_t) + hdrlen);
m->m_len += len;
} else {
uint32_t copymode;
/*
* Retain packet header metadata at the socket
* buffer if this is is an MPTCP subflow,
* otherwise move it.
*/
copymode = M_COPYM_MOVE_HDR;
#if MPTCP
if (so->so_flags & SOF_MP_SUBFLOW) {
copymode = M_COPYM_NOOP_HDR;
}
#endif /* MPTCP */
if (m != NULL) {
if (so->so_snd.sb_flags & SB_SENDHEAD) {
VERIFY(so->so_snd.sb_flags & SB_SENDHEAD);
VERIFY(so->so_snd.sb_sendoff <= so->so_snd.sb_cc);
m->m_next = m_copym_mode(so->so_snd.sb_mb,
off, (int)len, M_DONTWAIT,
&so->so_snd.sb_sendhead,
&so->so_snd.sb_sendoff, copymode);
VERIFY(so->so_snd.sb_sendoff <= so->so_snd.sb_cc);
} else {
m->m_next = m_copym_mode(so->so_snd.sb_mb,
off, (int)len, M_DONTWAIT,
NULL, NULL, copymode);
}
if (m->m_next == NULL) {
(void) m_free(m);
error = ENOBUFS;
goto out;
}
} else {
/*
* make sure we still have data left
* to be sent at this point
*/
if (so->so_snd.sb_mb == NULL) {
error = 0; /* should we return an error? */
goto out;
}
/*
* m_copym_with_hdrs will always return the
* last mbuf pointer and the offset into it that
* it acted on to fullfill the current request,
* whether a valid 'hint' was passed in or not.
*/
if (so->so_snd.sb_flags & SB_SENDHEAD) {
VERIFY(so->so_snd.sb_flags & SB_SENDHEAD);
VERIFY(so->so_snd.sb_sendoff <= so->so_snd.sb_cc);
m = m_copym_with_hdrs(so->so_snd.sb_mb,
off, len, M_DONTWAIT, &so->so_snd.sb_sendhead,
&so->so_snd.sb_sendoff, copymode);
VERIFY(so->so_snd.sb_sendoff <= so->so_snd.sb_cc);
} else {
m = m_copym_with_hdrs(so->so_snd.sb_mb,
off, len, M_DONTWAIT, NULL,
NULL, copymode);
}
if (m == NULL) {
error = ENOBUFS;
goto out;
}
m->m_data += max_linkhdr;
m->m_len = hdrlen;
}
}
/*
* If we're sending everything we've got, set PUSH.
* (This will keep happy those implementations which only
* give data to the user when a buffer fills or
* a PUSH comes in.)
*
* On SYN-segments we should not add the PUSH-flag.
*/
if (off + len == so->so_snd.sb_cc && !(flags & TH_SYN)) {
flags |= TH_PUSH;
}
} else {
if (tp->t_flags & TF_ACKNOW) {
tcpstat.tcps_sndacks++;
} else if (flags & (TH_SYN | TH_FIN | TH_RST)) {
tcpstat.tcps_sndctrl++;
} else if (SEQ_GT(tp->snd_up, tp->snd_una)) {
tcpstat.tcps_sndurg++;
} else {
tcpstat.tcps_sndwinup++;
}
MGETHDR(m, M_DONTWAIT, MT_HEADER); /* MAC-OK */
if (m == NULL) {
error = ENOBUFS;
goto out;
}
if (MHLEN < (hdrlen + max_linkhdr)) {
MCLGET(m, M_DONTWAIT);
if ((m->m_flags & M_EXT) == 0) {
m_freem(m);
error = ENOBUFS;
goto out;
}
}
m->m_data += max_linkhdr;
m->m_len = hdrlen;
}
m->m_pkthdr.rcvif = 0;
m_add_crumb(m, PKT_CRUMB_TCP_OUTPUT);
/* Any flag other than pure-ACK: Do not compress! */
if (flags & ~(TH_ACK)) {
do_not_compress = TRUE;
}
if (tp->rcv_scale == 0) {
do_not_compress = TRUE;
}
if (do_not_compress) {
m->m_pkthdr.comp_gencnt = 0;
} else {
if (TSTMP_LT(tp->t_comp_lastinc + tcp_ack_compression_rate, tcp_now_local)) {
tp->t_comp_gencnt++;
/* 0 means no compression, thus jump this */
if (tp->t_comp_gencnt <= TCP_ACK_COMPRESSION_DUMMY) {
tp->t_comp_gencnt = TCP_ACK_COMPRESSION_DUMMY + 1;
}
tp->t_comp_lastinc = tcp_now_local;
}
m->m_pkthdr.comp_gencnt = tp->t_comp_gencnt;
}
if (isipv6) {
ip6 = mtod(m, struct ip6_hdr *);
th = (struct tcphdr *)(void *)(ip6 + 1);
tcp_fillheaders(m, tp, ip6, th);
if (TCP_L4S_ENABLED(tp) && TCP_ACC_ECN_ON(tp)) {
/* We send ECT1 for ALL packets (data, control, fast retransmits, RTO) */
if ((tp->ecn_flags & TE_SENDIPECT) != 0 && !(flags & TH_SYN)) {
ip6->ip6_flow |= htonl(IPTOS_ECN_ECT1 << 20);
uint64_t tx_time = tcp_pacer_get_packet_tx_time(tp, (uint16_t)len);
if (tx_time) {
tcp_set_mbuf_tx_time(m, tx_time);
}
}
} else {
if ((tp->ecn_flags & TE_SENDIPECT) != 0 && len &&
!SEQ_LT(tp->snd_nxt, tp->snd_max) && !rack_sack_rxmit) {
ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20);
}
}
svc_flags |= PKT_SCF_IPV6;
#if PF_ECN
m_pftag(m)->pftag_hdr = (void *)ip6;
m_pftag(m)->pftag_flags |= PF_TAG_HDR_INET6;
#endif /* PF_ECN */
} else {
ip = mtod(m, struct ip *);
th = (struct tcphdr *)(void *)(ip + 1);
/* this picks up the pseudo header (w/o the length) */
tcp_fillheaders(m, tp, ip, th);
if (TCP_L4S_ENABLED(tp) && TCP_ACC_ECN_ON(tp)) {
/* We send ECT1 for ALL packets (data, control, fast retransmits, RTO) */
if ((tp->ecn_flags & TE_SENDIPECT) != 0 && !(flags & TH_SYN)) {
ip->ip_tos |= IPTOS_ECN_ECT1;
uint64_t tx_time = tcp_pacer_get_packet_tx_time(tp, (uint16_t)len);
if (tx_time) {
tcp_set_mbuf_tx_time(m, tx_time);
}
}
} else {
if ((tp->ecn_flags & TE_SENDIPECT) != 0 && len &&
!SEQ_LT(tp->snd_nxt, tp->snd_max) &&
!rack_sack_rxmit && !(flags & TH_SYN)) {
ip->ip_tos |= IPTOS_ECN_ECT0;
}
}
#if PF_ECN
m_pftag(m)->pftag_hdr = (void *)ip;
m_pftag(m)->pftag_flags |= PF_TAG_HDR_INET;
#endif /* PF_ECN */
}
/*
* Fill in fields, remembering maximum advertised
* window for use in delaying messages about window sizes.
* If resending a FIN, be sure not to use a new sequence number.
*/
if ((flags & TH_FIN) && (tp->t_flags & TF_SENTFIN) &&
tp->snd_nxt == tp->snd_max) {
tp->snd_nxt--;
}
/*
* If we are doing retransmissions, then snd_nxt will
* not reflect the first unsent octet. For ACK only
* packets, we do not want the sequence number of the
* retransmitted packet, we want the sequence number
* of the next unsent octet. So, if there is no data
* (and no SYN or FIN), use snd_max instead of snd_nxt
* when filling in ti_seq. But if we are in persist
* state, snd_max might reflect one byte beyond the
* right edge of the window, so use snd_nxt in that
* case, since we know we aren't doing a retransmission.
* (retransmit and persist are mutually exclusive...)
*
* Note the state of this retransmit segment to detect spurious
* retransmissions.
*/
if (rack_sack_rxmit == 0) {
if (len || (flags & (TH_SYN | TH_FIN)) ||
tp->t_timer[TCPT_PERSIST]) {
th->th_seq = htonl(tp->snd_nxt);
if (len > 0) {
m->m_pkthdr.tx_start_seq = tp->snd_nxt;
m->m_pkthdr.pkt_flags |= PKTF_START_SEQ;
}
if (SEQ_LT(tp->snd_nxt, tp->snd_max)) {
if (SACK_ENABLED(tp) && len > 1 &&
!(tp->t_flagsext & TF_SENT_TLPROBE)) {
tcp_rxtseg_insert(tp, tp->snd_nxt,
(tp->snd_nxt + len - 1));
}
if (len > 0) {
m->m_pkthdr.pkt_flags |=
PKTF_TCP_REXMT;
}
}
} else {
th->th_seq = htonl(tp->snd_max);
}
} else {
/* Use RACK if enabled otherwise use SACK */
if (TCP_RACK_ENABLED(tp)) {
th->th_seq = htonl(seg->start_seq);
tcp_rxtseg_insert(tp, seg->start_seq, (seg->start_seq + len - 1));
} else {
th->th_seq = htonl(p->rxmit);
tcp_rxtseg_insert(tp, p->rxmit, (p->rxmit + len - 1));
p->rxmit += len;
tp->sackhint.sack_bytes_rexmit += len;
}
if (len > 0) {
m->m_pkthdr.tx_start_seq = ntohl(th->th_seq);
m->m_pkthdr.pkt_flags |=
(PKTF_TCP_REXMT | PKTF_START_SEQ);
}
}
th->th_ack = htonl(tp->rcv_nxt);
tp->last_ack_sent = tp->rcv_nxt;
if (optlen) {
bcopy(opt, th + 1, optlen);
th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
}
/* Separate AE from flags */
th->th_flags = (flags & (TH_FLAGS_ALL));
th->th_x2 = (flags & (TH_AE)) >> 8;
th->th_win = htons((u_short) (recwin >> tp->rcv_scale));
tp->t_last_recwin = recwin;
if (!(so->so_flags & SOF_MP_SUBFLOW)) {
if (recwin > 0 && SEQ_LT(tp->rcv_adv, tp->rcv_nxt + recwin)) {
tp->rcv_adv = tp->rcv_nxt + recwin;
}
} else {
struct mptcb *mp_tp = tptomptp(tp);
if (recwin > 0) {
tp->rcv_adv = tp->rcv_nxt + recwin;
}
if (recwin > 0 && MPTCP_SEQ_LT(mp_tp->mpt_rcvadv, mp_tp->mpt_rcvnxt + recwin)) {
mp_tp->mpt_rcvadv = mp_tp->mpt_rcvnxt + recwin;
}
}
/*
* Adjust the RXWIN0SENT flag - indicate that we have advertised
* a 0 window. This may cause the remote transmitter to stall. This
* flag tells soreceive() to disable delayed acknowledgements when
* draining the buffer. This can occur if the receiver is attempting
* to read more data then can be buffered prior to transmitting on
* the connection.
*/
if (th->th_win == 0) {
tp->t_flags |= TF_RXWIN0SENT;
} else {
tp->t_flags &= ~TF_RXWIN0SENT;
}
if (SEQ_GT(tp->snd_up, tp->snd_nxt)) {
th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt));
th->th_flags |= TH_URG;
} else {
/*
* If no urgent pointer to send, then we pull
* the urgent pointer to the left edge of the send window
* so that it doesn't drift into the send window on sequence
* number wraparound.
*/
tp->snd_up = tp->snd_una; /* drag it along */
}
/*
* Put TCP length in extended header, and then
* checksum extended header and data.
*/
m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */
/*
* If this is potentially the last packet on the stream, then mark
* it in order to enable some optimizations in the underlying
* layers
*/
if (tp->t_state != TCPS_ESTABLISHED &&
(tp->t_state == TCPS_CLOSING || tp->t_state == TCPS_TIME_WAIT
|| tp->t_state == TCPS_LAST_ACK || (th->th_flags & TH_RST))) {
m->m_pkthdr.pkt_flags |= PKTF_LAST_PKT;
}
if (isipv6) {
/*
* ip6_plen is not need to be filled now, and will be filled
* in ip6_output.
*/
m->m_pkthdr.csum_flags = CSUM_TCPIPV6;
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
if (len + optlen) {
th->th_sum = in_addword(th->th_sum,
htons((u_short)(optlen + len)));
}
} else {
m->m_pkthdr.csum_flags = CSUM_TCP;
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
if (len + optlen) {
th->th_sum = in_addword(th->th_sum,
htons((u_short)(optlen + len)));
}
}
/*
* Enable TSO and specify the size of the segments.
* The TCP pseudo header checksum is always provided.
*/
if (tso) {
if (isipv6) {
m->m_pkthdr.csum_flags |= CSUM_TSO_IPV6;
} else {
m->m_pkthdr.csum_flags |= CSUM_TSO_IPV4;
}
m->m_pkthdr.tso_segsz = tp->t_maxopd - optlen;
} else {
m->m_pkthdr.tso_segsz = 0;
}
/*
* In transmit state, time the transmission and arrange for
* the retransmit. In persist state, just set snd_max.
*/
if (!(tp->t_flagsext & TF_FORCE)
|| tp->t_timer[TCPT_PERSIST] == 0) {
tcp_seq startseq = tp->snd_nxt;
/*
* Advance snd_nxt over sequence space of this segment.
*/
if (flags & (TH_SYN | TH_FIN)) {
if (flags & TH_SYN) {
tp->snd_nxt++;
}
if ((flags & TH_FIN) &&
!(tp->t_flags & TF_SENTFIN)) {
tp->snd_nxt++;
tp->t_flags |= TF_SENTFIN;
}
}
if (rack_sack_rxmit) {
goto timer;
}
if (sack_rescue_rxt == TRUE) {
tp->snd_nxt = old_snd_nxt;
sack_rescue_rxt = FALSE;
tcpstat.tcps_pto_in_recovery++;
} else {
tp->snd_nxt += len;
}
if (SEQ_GT(tp->snd_nxt, tp->snd_max)) {
tp->snd_max = tp->snd_nxt;
tp->t_sndtime = tcp_now_local;
/*
* Time this transmission if not a retransmission and
* not currently timing anything.
*/
if (tp->t_rtttime == 0) {
tp->t_rtttime = tcp_now_local;
tp->t_rtseq = startseq;
tcpstat.tcps_segstimed++;
/* update variables related to pipe ack */
tp->t_pipeack_lastuna = tp->snd_una;
}
}
/*
* Set retransmit timer if not currently set,
* and not doing an ack or a keep-alive probe.
*/
timer:
if (tp->t_timer[TCPT_REXMT] == 0 &&
((rack_sack_rxmit && tp->snd_nxt != tp->snd_max) ||
tp->snd_nxt != tp->snd_una || (flags & TH_FIN))) {
if (tp->t_timer[TCPT_PERSIST]) {
tp->t_timer[TCPT_PERSIST] = 0;
tp->t_persist_stop = 0;
TCP_RESET_REXMT_STATE(tp);
}
tp->t_timer[TCPT_REXMT] =
OFFSET_FROM_START(tp, tp->t_rxtcur);
}
/*
* Set tail loss probe timeout if new data is being
* transmitted. This will be supported only when
* SACK option is enabled on a connection.
*
* Every time new data is sent PTO will get reset.
*/
if (tcp_enable_tlp && len != 0 && tp->t_state == TCPS_ESTABLISHED &&
SACK_ENABLED(tp) && !IN_FASTRECOVERY(tp) &&
tp->snd_nxt == tp->snd_max &&
SEQ_GT(tp->snd_nxt, tp->snd_una) &&
tp->t_rxtshift == 0 &&
(tp->t_flagsext & (TF_SENT_TLPROBE | TF_PKTS_REORDERED)) == 0) {
uint32_t pto, srtt;
srtt = tp->t_srtt >> TCP_RTT_SHIFT;
pto = 2 * srtt;
if ((tp->snd_max - tp->snd_una) <= tp->t_maxseg) {
pto += tcp_delack;
} else {
pto += 2;
}
/* if RTO is less than PTO, choose RTO instead */
if (tp->t_rxtcur < pto) {
pto = tp->t_rxtcur;
}
tp->t_timer[TCPT_PTO] = OFFSET_FROM_START(tp, pto);
}
} else {
/*
* Persist case, update snd_max but since we are in
* persist mode (no window) we do not update snd_nxt.
*/
int xlen = len;
if (flags & TH_SYN) {
++xlen;
}
if ((flags & TH_FIN) &&
!(tp->t_flags & TF_SENTFIN)) {
++xlen;
tp->t_flags |= TF_SENTFIN;
}
if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max)) {
tp->snd_max = tp->snd_nxt + len;
tp->t_sndtime = tcp_now_local;
}
}
/*
* Fill in IP length and desired time to live and
* send to IP level. There should be a better way
* to handle ttl and tos; we could keep them in
* the template, but need a way to checksum without them.
*/
/*
* m->m_pkthdr.len should have been set before cksum calcuration,
* because in6_cksum() need it.
*/
if (isipv6) {
/*
* we separately set hoplimit for every segment, since the
* user might want to change the value via setsockopt.
* Also, desired default hop limit might be changed via
* Neighbor Discovery.
*/
ip6->ip6_hlim = in6_selecthlim(inp, inp->in6p_route.ro_rt ?
inp->in6p_route.ro_rt->rt_ifp : NULL);
/* Don't set ECT bit if requested by an app */
/* Set ECN bits for testing purposes */
if (tp->ecn_flags & TE_FORCE_ECT1) {
ip6->ip6_flow |= htonl(IPTOS_ECN_ECT1 << 20);
} else if (tp->ecn_flags & TE_FORCE_ECT0) {
ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20);
}
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)),
sendalot, 0, 0);
} else {
ASSERT(m->m_pkthdr.len <= IP_MAXPACKET);
ip->ip_len = (u_short)m->m_pkthdr.len;
ip->ip_ttl = inp->inp_ip_ttl; /* XXX */
/* Don't set ECN bit if requested by an app */
ip->ip_tos |= (inp->inp_ip_tos & ~IPTOS_ECN_MASK);
/* Set ECN bits for testing purposes */
if (tp->ecn_flags & TE_FORCE_ECT1) {
ip->ip_tos |= IPTOS_ECN_ECT1;
} else if (tp->ecn_flags & TE_FORCE_ECT0) {
ip->ip_tos |= IPTOS_ECN_ECT0;
}
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);
}
/*
* See if we should do MTU discovery.
* Look at the flag updated on the following criterias:
* 1) Path MTU discovery is authorized by the sysctl
* 2) The route isn't set yet (unlikely but could happen)
* 3) The route is up
* 4) the MTU is not locked (if it is, then discovery has been
* disabled for that route)
*/
if (!isipv6) {
if (path_mtu_discovery && (tp->t_flags & TF_PMTUD)) {
ip->ip_off |= IP_DF;
}
}
#if NECP
{
necp_kernel_policy_id policy_id;
necp_kernel_policy_id skip_policy_id;
u_int32_t route_rule_id;
u_int32_t pass_flags;
if (!necp_socket_is_allowed_to_send_recv(inp, NULL, 0, &policy_id, &route_rule_id, &skip_policy_id, &pass_flags)) {
TCP_LOG_DROP_NECP(isipv6 ? (void *)ip6 : (void *)ip, th, tp, true);
m_freem(m);
error = EHOSTUNREACH;
goto out;
}
necp_mark_packet_from_socket(m, inp, policy_id, route_rule_id, skip_policy_id, pass_flags);
if (net_qos_policy_restricted != 0) {
necp_socket_update_qos_marking(inp, inp->inp_route.ro_rt, route_rule_id);
}
}
#endif /* NECP */
#if IPSEC
if (inp->inp_sp != NULL) {
ipsec_setsocket(m, so);
}
#endif /*IPSEC*/
/*
* The socket is kept locked while sending out packets in ip_output, even if packet chaining is not active.
*/
lost = 0;
/*
* Embed the flow hash in pkt hdr and mark the packet as
* capable of flow controlling
*/
m->m_pkthdr.pkt_flowsrc = FLOWSRC_INPCB;
m->m_pkthdr.pkt_flowid = inp->inp_flowhash;
m->m_pkthdr.pkt_flags |= (PKTF_FLOW_ID | PKTF_FLOW_LOCALSRC | PKTF_FLOW_ADV);
m->m_pkthdr.pkt_proto = IPPROTO_TCP;
m->m_pkthdr.tx_tcp_pid = so->last_pid;
if (so->so_flags & SOF_DELEGATED) {
m->m_pkthdr.tx_tcp_e_pid = so->e_pid;
} else {
m->m_pkthdr.tx_tcp_e_pid = 0;
}
m->m_nextpkt = NULL;
if (inp->inp_last_outifp != NULL &&
!(inp->inp_last_outifp->if_flags & IFF_LOOPBACK)) {
/* Hint to prioritize this packet if
* 1. if the packet has no data
* 2. the interface supports transmit-start model and did
* not disable ACK prioritization.
* 3. Only ACK flag is set.
* 4. there is no outstanding data on this connection.
*/
if (len == 0 && (inp->inp_last_outifp->if_eflags & (IFEF_TXSTART | IFEF_NOACKPRI)) == IFEF_TXSTART) {
if (th->th_flags == TH_ACK &&
tp->snd_una == tp->snd_max &&
tp->t_timer[TCPT_REXMT] == 0) {
svc_flags |= PKT_SCF_TCP_ACK;
}
if (th->th_flags & TH_SYN) {
svc_flags |= PKT_SCF_TCP_SYN;
}
}
set_packet_service_class(m, so, sotc, svc_flags);
} else {
/*
* Optimization for loopback just set the mbuf
* service class
*/
(void) m_set_service_class(m, so_tc2msc(sotc));
}
if ((th->th_flags & TH_SYN) && tp->t_syn_sent < UINT8_MAX) {
tp->t_syn_sent++;
}
if ((th->th_flags & TH_FIN) && tp->t_fin_sent < UINT8_MAX) {
tp->t_fin_sent++;
}
if ((th->th_flags & TH_RST) && tp->t_rst_sent < UINT8_MAX) {
tp->t_rst_sent++;
}
TCP_LOG_TH_FLAGS(isipv6 ? (void *)ip6 : (void *)ip, th, tp, true,
inp->inp_last_outifp != NULL ? inp->inp_last_outifp :
inp->inp_boundifp);
tp->t_pktlist_sentlen += len;
tp->t_lastchain++;
if (isipv6) {
DTRACE_TCP5(send, struct mbuf *, m, struct inpcb *, inp,
struct ip6 *, ip6, struct tcpcb *, tp, struct tcphdr *,
th);
} else {
DTRACE_TCP5(send, struct mbuf *, m, struct inpcb *, inp,
struct ip *, ip, struct tcpcb *, tp, struct tcphdr *, th);
}
if (tp->t_pktlist_head != NULL) {
tp->t_pktlist_tail->m_nextpkt = m;
tp->t_pktlist_tail = m;
} else {
packchain_newlist++;
tp->t_pktlist_head = tp->t_pktlist_tail = m;
}
/* Append segment to time-ordered list and RB tree used for RACK */
if (TCP_RACK_ENABLED(tp) && len) {
uint8_t retransmit_flag = 0;
if (tp->t_flagsext & TF_SENT_TLPROBE) {
/* Only set the at least once retransmitted flag */
retransmit_flag = (m->m_pkthdr.pkt_flags & PKTF_TCP_REXMT) ? TCP_SEGMENT_RETRANSMITTED_ATLEAST_ONCE : 0;
} else {
/* Set both RACK and EVER retransmitted flags */
retransmit_flag = (m->m_pkthdr.pkt_flags & PKTF_TCP_REXMT) ? TCP_SEGMENT_RETRANSMITTED : 0;
}
tcp_seg_sent_insert(tp, seg, ntohl(th->th_seq), ntohl(th->th_seq) + len, tcp_now_local, retransmit_flag);
}
if (sendalot == 0 || (tp->t_state != TCPS_ESTABLISHED) ||
(tp->t_flags & TF_ACKNOW) ||
(tp->t_flagsext & TF_FORCE) ||
tp->t_lastchain >= tcp_packet_chaining) {
error = 0;
while (inp->inp_sndinprog_cnt == 0 &&
tp->t_pktlist_head != NULL) {
packetlist = tp->t_pktlist_head;
packchain_listadd = tp->t_lastchain;
packchain_sent++;
lost = tp->t_pktlist_sentlen;
TCP_PKTLIST_CLEAR(tp);
error = tcp_ip_output(so, tp, packetlist,
packchain_listadd, tp_inp_options,
(so_options & SO_DONTROUTE),
(rack_sack_rxmit || (sack_bytes_rxmt != 0)), isipv6);
if (error) {
/*
* Take into account the rest of unsent
* packets in the packet list for this tcp
* into "lost", since we're about to free
* the whole list below.
*/
lost += tp->t_pktlist_sentlen;
break;
} else {
lost = 0;
}
}
/* tcp was closed while we were in ip; resume close */
if (inp->inp_sndinprog_cnt == 0 &&
(tp->t_flags & TF_CLOSING)) {
tp->t_flags &= ~TF_CLOSING;
(void) tcp_close(tp);
return 0;
}
} else {
error = 0;
packchain_looped++;
tcpstat.tcps_sndtotal++;
goto again;
}
if (error) {
/*
* Assume that the packets were lost, so back out the
* sequence number advance, if any. Note that the "lost"
* variable represents the amount of user data sent during
* the recent call to ip_output_list() plus the amount of
* user data in the packet list for this tcp at the moment.
*/
if (!(tp->t_flagsext & TF_FORCE)
|| tp->t_timer[TCPT_PERSIST] == 0) {
/*
* No need to check for TH_FIN here because
* the TF_SENTFIN flag handles that case.
*/
if ((flags & TH_SYN) == 0) {
/*
* RACK will mark these segments lost on its own
* when new ACK arrives, no need to adjust anything here.
* In fact doing so would be wrong, as RACK segments are
* ordered in time (not sequence number).
*/
if (rack_sack_rxmit && !TCP_RACK_ENABLED(tp)) {
if (SEQ_GT((p->rxmit - lost),
tp->snd_una)) {
p->rxmit -= lost;
if (SEQ_LT(p->rxmit, p->start)) {
p->rxmit = p->start;
}
} else {
lost = p->rxmit - tp->snd_una;
p->rxmit = tp->snd_una;
if (SEQ_LT(p->rxmit, p->start)) {
p->rxmit = p->start;
}
}
tp->sackhint.sack_bytes_rexmit -= lost;
if (tp->sackhint.sack_bytes_rexmit < 0) {
tp->sackhint.sack_bytes_rexmit = 0;
}
} else {
if (SEQ_GT((tp->snd_nxt - lost),
tp->snd_una)) {
tp->snd_nxt -= lost;
} else {
tp->snd_nxt = tp->snd_una;
}
}
}
}
out:
if (tp->t_pktlist_head != NULL) {
m_freem_list(tp->t_pktlist_head);
}
TCP_PKTLIST_CLEAR(tp);
if (error == ENOBUFS) {
/*
* Set retransmit timer if not currently set
* when we failed to send a segment that can be
* retransmitted (i.e. not pure ack or rst)
*/
if (tp->t_timer[TCPT_REXMT] == 0 &&
tp->t_timer[TCPT_PERSIST] == 0 &&
(len != 0 || (flags & (TH_SYN | TH_FIN)) != 0 ||
so->so_snd.sb_cc > 0)) {
tp->t_timer[TCPT_REXMT] =
OFFSET_FROM_START(tp, tp->t_rxtcur);
}
tp->snd_cwnd = tp->t_maxseg;
tp->t_bytes_acked = 0;
tcp_check_timer_state(tp);
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
TCP_LOG_OUTPUT(tp, "error ENOBUFS silently handled");
tcp_ccdbg_trace(tp, NULL, TCP_CC_OUTPUT_ERROR);
return 0;
}
if (error == EMSGSIZE) {
/*
* ip_output() will have already fixed the route
* for us. tcp_mtudisc() will, as its last action,
* initiate retransmission, so it is important to
* not do so here.
*
* If TSO was active we either got an interface
* without TSO capabilits or TSO was turned off.
* Disable it for this connection as too and
* immediatly retry with MSS sized segments generated
* by this function.
*/
if (tso) {
tp->t_flags &= ~TF_TSO;
}
tcp_mtudisc(inp, 0);
tcp_check_timer_state(tp);
TCP_LOG_OUTPUT(tp, "error EMSGSIZE silently handled");
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
return 0;
}
/*
* Unless this is due to interface restriction policy,
* treat EHOSTUNREACH/ENETDOWN/EADDRNOTAVAIL as a soft error.
*/
if ((error == EHOSTUNREACH || error == ENETDOWN || error == EADDRNOTAVAIL) &&
TCPS_HAVERCVDSYN(tp->t_state) &&
!inp_restricted_send(inp, inp->inp_last_outifp)) {
tp->t_softerror = error;
TCP_LOG_OUTPUT(tp, "soft error %d silently handled", error);
error = 0;
} else {
TCP_LOG_OUTPUT(tp, "error %d", error);
}
tcp_check_timer_state(tp);
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
return error;
}
tcpstat.tcps_sndtotal++;
KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_END, 0, 0, 0, 0, 0);
if (sendalot) {
goto again;
}
tcp_check_timer_state(tp);
return 0;
}
static int
tcp_ip_output(struct socket *so, struct tcpcb *tp, struct mbuf *pkt,
int cnt, struct mbuf *opt, int flags, int sack_in_progress, boolean_t isipv6)
{
int error = 0;
boolean_t chain;
boolean_t unlocked = FALSE;
boolean_t ifdenied = FALSE;
struct inpcb *__single inp = tp->t_inpcb;
struct ifnet *__single outif = NULL;
bool check_qos_marking_again = (so->so_flags1 & SOF1_QOSMARKING_POLICY_OVERRIDE) ? FALSE : TRUE;
union {
struct route _ro;
struct route_in6 _ro6;
} route_u_ = {};
#define ro route_u_._ro
#define ro6 route_u_._ro6
union {
struct ip_out_args _ipoa;
struct ip6_out_args _ip6oa;
} out_args_u_ = {};
#define ipoa out_args_u_._ipoa
#define ip6oa out_args_u_._ip6oa
if (isipv6) {
ip6oa.ip6oa_boundif = IFSCOPE_NONE;
ip6oa.ip6oa_flags = IP6OAF_SELECT_SRCIF | IP6OAF_BOUND_SRCADDR;
ip6oa.ip6oa_sotc = SO_TC_UNSPEC;
ip6oa.ip6oa_netsvctype = _NET_SERVICE_TYPE_UNSPEC;
} else {
ipoa.ipoa_boundif = IFSCOPE_NONE;
ipoa.ipoa_flags = IPOAF_SELECT_SRCIF | IPOAF_BOUND_SRCADDR;
ipoa.ipoa_sotc = SO_TC_UNSPEC;
ipoa.ipoa_netsvctype = _NET_SERVICE_TYPE_UNSPEC;
}
struct flowadv *__single adv =
(isipv6 ? &ip6oa.ip6oa_flowadv : &ipoa.ipoa_flowadv);
/* If socket was bound to an ifindex, tell ip_output about it */
if (inp->inp_flags & INP_BOUND_IF) {
if (isipv6) {
ip6oa.ip6oa_boundif = inp->inp_boundifp->if_index;
ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;
} else {
ipoa.ipoa_boundif = inp->inp_boundifp->if_index;
ipoa.ipoa_flags |= IPOAF_BOUND_IF;
}
} else if (!in6_embedded_scope && isipv6 && (IN6_IS_SCOPE_EMBED(&inp->in6p_faddr))) {
ip6oa.ip6oa_boundif = inp->inp_fifscope;
ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF;
}
if (INP_NO_CELLULAR(inp)) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_NO_CELLULAR;
} else {
ipoa.ipoa_flags |= IPOAF_NO_CELLULAR;
}
}
if (INP_NO_EXPENSIVE(inp)) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_NO_EXPENSIVE;
} else {
ipoa.ipoa_flags |= IPOAF_NO_EXPENSIVE;
}
}
if (INP_NO_CONSTRAINED(inp)) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_NO_CONSTRAINED;
} else {
ipoa.ipoa_flags |= IPOAF_NO_CONSTRAINED;
}
}
if (INP_AWDL_UNRESTRICTED(inp)) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_AWDL_UNRESTRICTED;
} else {
ipoa.ipoa_flags |= IPOAF_AWDL_UNRESTRICTED;
}
}
if (INP_INTCOPROC_ALLOWED(inp) && isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_INTCOPROC_ALLOWED;
}
if (INP_MANAGEMENT_ALLOWED(inp)) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_MANAGEMENT_ALLOWED;
} else {
ipoa.ipoa_flags |= IPOAF_MANAGEMENT_ALLOWED;
}
}
if (isipv6) {
ip6oa.ip6oa_sotc = so->so_traffic_class;
ip6oa.ip6oa_netsvctype = so->so_netsvctype;
ip6oa.qos_marking_gencount = inp->inp_policyresult.results.qos_marking_gencount;
} else {
ipoa.ipoa_sotc = so->so_traffic_class;
ipoa.ipoa_netsvctype = so->so_netsvctype;
ipoa.qos_marking_gencount = inp->inp_policyresult.results.qos_marking_gencount;
}
if ((so->so_flags1 & SOF1_QOSMARKING_ALLOWED)) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_QOSMARKING_ALLOWED;
} else {
ipoa.ipoa_flags |= IPOAF_QOSMARKING_ALLOWED;
}
}
if (check_qos_marking_again) {
if (isipv6) {
ip6oa.ip6oa_flags |= IP6OAF_REDO_QOSMARKING_POLICY;
} else {
ipoa.ipoa_flags |= IPOAF_REDO_QOSMARKING_POLICY;
}
}
if (isipv6) {
flags |= IPV6_OUTARGS;
} else {
flags |= IP_OUTARGS;
}
/* Copy the cached route and take an extra reference */
if (isipv6) {
in6p_route_copyout(inp, &ro6);
} else {
inp_route_copyout(inp, &ro);
}
#if (DEBUG || DEVELOPMENT)
if ((so->so_flags & SOF_MARK_WAKE_PKT) && pkt != NULL) {
so->so_flags &= ~SOF_MARK_WAKE_PKT;
pkt->m_pkthdr.pkt_flags |= PKTF_WAKE_PKT;
}
#endif /* (DEBUG || DEVELOPMENT) */
/*
* Make sure ACK/DELACK conditions are cleared before
* we unlock the socket.
*/
tp->last_ack_sent = tp->rcv_nxt;
tp->t_flags &= ~(TF_ACKNOW | TF_DELACK);
tp->t_timer[TCPT_DELACK] = 0;
tp->t_unacksegs = 0;
tp->t_unacksegs_ce = 0;
/* Increment the count of outstanding send operations */
inp->inp_sndinprog_cnt++;
/*
* If allowed, unlock TCP socket while in IP
* but only if the connection is established and
* in a normal mode where reentrancy on the tcpcb won't be
* an issue:
* - there is no SACK episode
* - we're not in Fast Recovery mode
* - if we're not sending from an upcall.
*/
if (tcp_output_unlocked && !so->so_upcallusecount &&
(tp->t_state == TCPS_ESTABLISHED) && (sack_in_progress == 0) &&
!IN_FASTRECOVERY(tp) && !(so->so_flags & SOF_MP_SUBFLOW)) {
unlocked = TRUE;
socket_unlock(so, 0);
}
/*
* Don't send down a chain of packets when:
* - TCP chaining is disabled
* - there is an IPsec rule set
* - there is a non default rule set for the firewall
*/
chain = tcp_packet_chaining > 1
#if IPSEC
&& ipsec_bypass
#endif
; // I'm important, not extraneous
while (pkt != NULL) {
struct mbuf *npkt = pkt->m_nextpkt;
if (!chain) {
pkt->m_nextpkt = NULL;
/*
* If we are not chaining, make sure to set the packet
* list count to 0 so that IP takes the right path;
* this is important for cases such as IPsec where a
* single mbuf might result in multiple mbufs as part
* of the encapsulation. If a non-zero count is passed
* down to IP, the head of the chain might change and
* we could end up skipping it (thus generating bogus
* packets). Fixing it in IP would be desirable, but
* for now this would do it.
*/
cnt = 0;
}
if (isipv6) {
error = ip6_output_list(pkt, cnt,
inp->in6p_outputopts, &ro6, flags, NULL, NULL,
&ip6oa);
ifdenied = (ip6oa.ip6oa_flags & IP6OAF_R_IFDENIED);
} else {
error = ip_output_list(pkt, cnt, opt, &ro, flags, NULL,
&ipoa);
ifdenied = (ipoa.ipoa_flags & IPOAF_R_IFDENIED);
}
if (chain || error) {
/*
* If we sent down a chain then we are done since
* the callee had taken care of everything; else
* we need to free the rest of the chain ourselves.
*/
if (!chain) {
m_freem_list(npkt);
}
break;
}
pkt = npkt;
}
if (unlocked) {
socket_lock(so, 0);
}
/*
* Enter flow controlled state if the connection is established
* and is not in recovery. Flow control is allowed only if there
* is outstanding data.
*
* A connection will enter suspended state even if it is in
* recovery.
*/
if (((adv->code == FADV_FLOW_CONTROLLED && !IN_FASTRECOVERY(tp)) ||
adv->code == FADV_SUSPENDED) &&
!(tp->t_flags & TF_CLOSING) &&
tp->t_state == TCPS_ESTABLISHED &&
SEQ_GT(tp->snd_max, tp->snd_una)) {
int rc;
rc = inp_set_fc_state(inp, adv->code);
if (rc == 1) {
tcp_ccdbg_trace(tp, NULL,
((adv->code == FADV_FLOW_CONTROLLED) ?
TCP_CC_FLOW_CONTROL : TCP_CC_SUSPEND));
if (adv->code == FADV_FLOW_CONTROLLED) {
TCP_LOG_OUTPUT(tp, "flow controlled");
} else {
TCP_LOG_OUTPUT(tp, "flow suspended");
}
}
}
/*
* When an interface queue gets suspended, some of the
* packets are dropped. Return ENOBUFS, to update the
* pcb state.
*/
if (adv->code == FADV_SUSPENDED) {
error = ENOBUFS;
}
VERIFY(inp->inp_sndinprog_cnt > 0);
if (--inp->inp_sndinprog_cnt == 0) {
inp->inp_flags &= ~(INP_FC_FEEDBACK);
if (inp->inp_sndingprog_waiters > 0) {
wakeup(&inp->inp_sndinprog_cnt);
}
}
if (isipv6) {
/*
* When an NECP IP tunnel policy forces the outbound interface,
* ip6_output_list() informs the transport layer what is the actual
* outgoing interface
*/
if (ip6oa.ip6oa_flags & IP6OAF_BOUND_IF) {
outif = ifindex2ifnet[ip6oa.ip6oa_boundif];
} else if (ro6.ro_rt != NULL) {
outif = ro6.ro_rt->rt_ifp;
}
} else {
if (ro.ro_rt != NULL) {
outif = ro.ro_rt->rt_ifp;
}
}
if (check_qos_marking_again) {
uint32_t qos_marking_gencount;
bool allow_qos_marking;
if (isipv6) {
qos_marking_gencount = ip6oa.qos_marking_gencount;
allow_qos_marking = ip6oa.ip6oa_flags & IP6OAF_QOSMARKING_ALLOWED ? TRUE : FALSE;
} else {
qos_marking_gencount = ipoa.qos_marking_gencount;
allow_qos_marking = ipoa.ipoa_flags & IPOAF_QOSMARKING_ALLOWED ? TRUE : FALSE;
}
inp->inp_policyresult.results.qos_marking_gencount = qos_marking_gencount;
if (allow_qos_marking == TRUE) {
inp->inp_socket->so_flags1 |= SOF1_QOSMARKING_ALLOWED;
} else {
inp->inp_socket->so_flags1 &= ~SOF1_QOSMARKING_ALLOWED;
}
}
if (outif != NULL && outif != inp->inp_last_outifp) {
/* Update the send byte count */
if (so->so_snd.sb_cc > 0 && so->so_snd.sb_flags & SB_SNDBYTE_CNT) {
inp_decr_sndbytes_total(so, so->so_snd.sb_cc);
inp_decr_sndbytes_allunsent(so, tp->snd_una);
so->so_snd.sb_flags &= ~SB_SNDBYTE_CNT;
}
inp->inp_last_outifp = outif;
#if SKYWALK
if (NETNS_TOKEN_VALID(&inp->inp_netns_token)) {
netns_set_ifnet(&inp->inp_netns_token, inp->inp_last_outifp);
}
#endif /* SKYWALK */
}
if (error != 0 && ifdenied &&
(INP_NO_CELLULAR(inp) || INP_NO_EXPENSIVE(inp) || INP_NO_CONSTRAINED(inp))) {
soevent(so,
(SO_FILT_HINT_LOCKED | SO_FILT_HINT_IFDENIED));
}
/* Synchronize cached PCB route & options */
if (isipv6) {
in6p_route_copyin(inp, &ro6);
} else {
inp_route_copyin(inp, &ro);
}
if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift == 0 &&
tp->t_inpcb->inp_route.ro_rt != NULL) {
/* If we found the route and there is an rtt on it
* reset the retransmit timer
*/
tcp_getrt_rtt(tp, tp->t_inpcb->in6p_route.ro_rt);
tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur);
}
return error;
#undef ro
#undef ro6
#undef ipoa
#undef ip6oa
}
int tcptv_persmin_val = TCPTV_PERSMIN;
void
tcp_setpersist(struct tcpcb *tp)
{
int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
/* If a PERSIST_TIMER option was set we will limit the
* time the persist timer will be active for that connection
* in order to avoid DOS by using zero window probes.
* see rdar://5805356
*/
if (tp->t_persist_timeout != 0 &&
tp->t_timer[TCPT_PERSIST] == 0 &&
tp->t_persist_stop == 0) {
tp->t_persist_stop = tcp_now + tp->t_persist_timeout;
}
/*
* Start/restart persistance timer.
*/
TCPT_RANGESET(tp->t_timer[TCPT_PERSIST],
t * tcp_backoff[tp->t_rxtshift],
tcptv_persmin_val, TCPTV_PERSMAX, 0);
tp->t_timer[TCPT_PERSIST] = OFFSET_FROM_START(tp, tp->t_timer[TCPT_PERSIST]);
if (tp->t_rxtshift < TCP_MAXRXTSHIFT) {
tp->t_rxtshift++;
}
}
static int
tcp_recv_throttle(struct tcpcb *tp)
{
uint32_t base_rtt, newsize;
struct sockbuf *__single sbrcv = &tp->t_inpcb->inp_socket->so_rcv;
if (tcp_use_rtt_recvbg == 1 &&
TSTMP_SUPPORTED(tp)) {
/*
* Timestamps are supported on this connection. Use
* RTT to look for an increase in latency.
*/
/*
* If the connection is already being throttled, leave it
* in that state until rtt comes closer to base rtt
*/
if (tp->t_flagsext & TF_RECV_THROTTLE) {
return 1;
}
base_rtt = get_base_rtt(tp);
if (base_rtt != 0 && tp->t_rttcur != 0) {
/*
* if latency increased on a background flow,
* return 1 to start throttling.
*/
if (tp->t_rttcur > (base_rtt + target_qdelay)) {
tp->t_flagsext |= TF_RECV_THROTTLE;
if (tp->t_recv_throttle_ts == 0) {
tp->t_recv_throttle_ts = tcp_now;
}
/*
* Reduce the recv socket buffer size to
* minimize latecy.
*/
if (sbrcv->sb_idealsize >
tcp_recv_throttle_minwin) {
newsize = sbrcv->sb_idealsize >> 1;
/* Set a minimum of 16 K */
newsize =
max(newsize,
tcp_recv_throttle_minwin);
sbrcv->sb_idealsize = newsize;
}
return 1;
} else {
return 0;
}
}
}
/*
* Timestamps are not supported or there is no good RTT
* measurement. Use IPDV in this case.
*/
if (tp->acc_iaj > tcp_acc_iaj_react_limit) {
return 1;
}
return 0;
}