/* * Copyright (c) 2000-2014 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if INET6 #include #include #include #endif #include #define TCPOUTFLAGS #include #include #include #include #include #include #if TCPDEBUG #include #endif #include #include #if IPSEC #include #endif /*IPSEC*/ #if CONFIG_MACF_NET #include #endif /* MAC_SOCKET */ #include #if MPTCP #include #include #include #endif #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) int path_mtu_discovery = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_RW | CTLFLAG_LOCKED, &path_mtu_discovery, 1, "Enable Path MTU Discovery"); int ss_fltsz = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, slowstart_flightsize, CTLFLAG_RW | CTLFLAG_LOCKED,&ss_fltsz, 1, "Slow start flight size"); int ss_fltsz_local = 8; /* starts with eight segments max */ SYSCTL_INT(_net_inet_tcp, OID_AUTO, local_slowstart_flightsize, CTLFLAG_RW | CTLFLAG_LOCKED, &ss_fltsz_local, 1, "Slow start flight size for local networks"); int tcp_do_tso = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_do_tso, 0, "Enable TCP Segmentation Offload"); int tcp_ecn_outbound = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, ecn_initiate_out, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_ecn_outbound, 0, "Initiate ECN for outbound connections"); int tcp_ecn_inbound = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, ecn_negotiate_in, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_ecn_inbound, 0, "Allow ECN negotiation for inbound connections"); int tcp_packet_chaining = 50; SYSCTL_INT(_net_inet_tcp, OID_AUTO, packetchain, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_packet_chaining, 0, "Enable TCP output packet chaining"); int tcp_output_unlocked = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, socket_unlocked_on_output, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_output_unlocked, 0, "Unlock TCP when sending packets down to IP"); int tcp_do_rfc3390 = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_do_rfc3390, 1, "Calculate intial slowstart cwnd depending on MSS"); int tcp_min_iaj_win = MIN_IAJ_WIN; SYSCTL_INT(_net_inet_tcp, OID_AUTO, min_iaj_win, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_min_iaj_win, 1, "Minimum recv win based on inter-packet arrival jitter"); int tcp_acc_iaj_react_limit = ACC_IAJ_REACT_LIMIT; SYSCTL_INT(_net_inet_tcp, OID_AUTO, acc_iaj_react_limit, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_acc_iaj_react_limit, 1, "Accumulated IAJ when receiver starts to react"); uint32_t tcp_do_autosendbuf = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, doautosndbuf, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_do_autosendbuf, 1, "Enable send socket buffer auto-tuning"); uint32_t tcp_autosndbuf_inc = 8 * 1024; SYSCTL_INT(_net_inet_tcp, OID_AUTO, autosndbufinc, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_autosndbuf_inc, 1, "Increment in send socket bufffer size"); uint32_t tcp_autosndbuf_max = 512 * 1024; SYSCTL_INT(_net_inet_tcp, OID_AUTO, autosndbufmax, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_autosndbuf_max, 1, "Maximum send socket buffer size"); uint32_t tcp_prioritize_acks = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, ack_prioritize, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_prioritize_acks, 1, "Prioritize pure acks"); uint32_t tcp_use_rtt_recvbg = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, rtt_recvbg, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_use_rtt_recvbg, 1, "Use RTT for bg recv algorithm"); uint32_t tcp_recv_throttle_minwin = 16 * 1024; SYSCTL_INT(_net_inet_tcp, OID_AUTO, recv_throttle_minwin, CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_recv_throttle_minwin, 1, "Minimum recv win for throttling"); int32_t tcp_enable_tlp = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, enable_tlp, CTLFLAG_RW | CTLFLAG_LOCKED, &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 */ #if IPFIREWALL extern int fw_enable; /* firewall check for packet chaining */ extern int fw_bypass; /* firewall check: disable packet chaining if there is rules */ #endif /* IPFIREWALL */ extern u_int32_t dlil_filter_disable_tso_count; extern u_int32_t kipf_count; extern int tcp_recv_bg; static int tcp_ip_output(struct socket *, struct tcpcb *, struct mbuf *, int, struct mbuf *, int, int, int32_t, boolean_t); static struct mbuf* tcp_send_lroacks(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th); static int tcp_recv_throttle(struct tcpcb *tp); /* * 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) { struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; int32_t len, recwin, sendwin, off; int flags, error; struct mbuf *m; struct ip *ip = NULL; struct ipovly *ipov = NULL; #if INET6 struct ip6_hdr *ip6 = NULL; #endif /* INET6 */ struct tcphdr *th; u_char opt[TCP_MAXOLEN]; unsigned ipoptlen, optlen, hdrlen; int idle, sendalot, lost = 0; int i, sack_rxmit; int tso = 0; int sack_bytes_rxmt; struct sackhole *p; #if IPSEC unsigned ipsec_optlen = 0; #endif /* IPSEC */ int idle_time = 0; struct mbuf *packetlist = NULL; struct mbuf *tp_inp_options = inp->inp_depend4.inp4_options; #if INET6 int isipv6 = inp->inp_vflag & INP_IPV6 ; #endif short packchain_listadd = 0; int so_options = so->so_options; struct rtentry *rt; u_int32_t basertt, svc_flags = 0, allocated_len; u_int32_t lro_ackmore = (tp->t_lropktlen != 0) ? 1 : 0; struct mbuf *mnext = NULL; int sackoptlen = 0; #if MPTCP unsigned int *dlenp = NULL; u_int8_t *finp = NULL; u_int32_t *sseqp = NULL; u_int64_t dss_val = 0; boolean_t mptcp_acknow = FALSE; boolean_t early_data_sent = FALSE; #endif /* MPTCP */ boolean_t cell = FALSE; boolean_t wifi = FALSE; boolean_t wired = 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 - tp->t_rcvtime; if (idle && idle_time >= TCP_IDLETIMEOUT(tp)) { if (CC_ALGO(tp)->after_idle != NULL) CC_ALGO(tp)->after_idle(tp); tcp_ccdbg_trace(tp, NULL, TCP_CC_IDLE_TIMEOUT); } 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: KERNEL_DEBUG(DBG_FNC_TCP_OUTPUT | DBG_FUNC_START, 0,0,0,0,0); #if INET6 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 #endif { 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]) { tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, tp->t_rxtcur); if (tp->t_timer[TCPT_PERSIST]) { tp->t_timer[TCPT_PERSIST] = 0; tp->t_rxtshift = 0; tp->t_persist_stop = 0; tp->t_rxtstart = 0; } } 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_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)); } 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) { cell = IFNET_IS_CELLULAR(rt->rt_ifp); wifi = (!cell && IFNET_IS_WIFI(rt->rt_ifp)); wired = (!wifi && IFNET_IS_WIRED(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. */ if (SACK_ENABLED(tp) && SEQ_LT(tp->snd_nxt, tp->snd_max)) 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. */ sack_rxmit = 0; sack_bytes_rxmt = 0; len = 0; p = NULL; if (SACK_ENABLED(tp) && IN_FASTRECOVERY(tp) && (p = tcp_sack_output(tp, &sack_bytes_rxmt))) { int32_t cwin; cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt; if (cwin < 0) cwin = 0; /* 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; sack_rxmit = 1; sendalot = 1; tcpstat.tcps_sack_rexmits++; tcpstat.tcps_sack_rexmit_bytes += min(len, tp->t_maxseg); if (nstat_collect) { nstat_route_tx(inp->inp_route.ro_rt, 1, min(len, tp->t_maxseg), NSTAT_TX_FLAG_RETRANSMIT); INP_ADD_STAT(inp, cell, wifi, wired, txpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, txbytes, min(len, tp->t_maxseg)); tp->t_stat.txretransmitbytes += 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 (tp->t_flags & TF_NEEDSYN) flags |= TH_SYN; /* * 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_rxtshift = 0; tp->t_rxtstart = 0; tp->t_persist_stop = 0; } } /* * 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 is true we are retransmitting from the scoreboard * in which case len is already set. */ if (sack_rxmit == 0) { if (sack_bytes_rxmt == 0) len = min(so->so_snd.sb_cc, sendwin) - off; else { int32_t cwin; /* * 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) { cwin = tp->snd_cwnd - (tp->snd_nxt - tp->sack_newdata) - sack_bytes_rxmt; if (cwin < 0) cwin = 0; len = imin(len, cwin); } else len = 0; } } #if MPTCP if ((tp->t_mpflags & TMPF_FASTJOIN_SEND) && (tp->t_state == TCPS_SYN_SENT) && (!(tp->t_flags & TF_CLOSING)) && (so->so_snd.sb_cc != 0) && (tp->t_rxtshift == 0)) { flags &= ~TH_SYN; flags |= TH_ACK; off = 0; len = min(so->so_snd.sb_cc, tp->t_maxseg); early_data_sent = TRUE; } else if (early_data_sent) { /* for now, we allow only one data segment to be sent */ return (0); } #endif /* MPTCP */ /* * 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) 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), (sack_rxmit | (sack_bytes_rxmt != 0)), 0, #if INET6 isipv6); #else /* INET6 */ 0); #endif /* !INET6 */ } /* * 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. */ if ((flags & TH_SYN) && (tp->t_flags & TF_NOOPT)) { len = 0; flags &= ~TH_FIN; } /* * 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; tp->t_rxtshift = 0; tp->t_rxtstart = 0; 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. */ basertt = get_base_rtt(tp); if (tcp_do_autosendbuf == 1 && !INP_WAIT_FOR_IF_FEEDBACK(inp) && !IN_FASTRECOVERY(tp) && (so->so_snd.sb_flags & (SB_AUTOSIZE | SB_TRIM)) == SB_AUTOSIZE && tcp_cansbgrow(&so->so_snd)) { 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))) { /* Also increase the send buffer only if the * round-trip time is not increasing because we do * not want to contribute to latency by filling * buffers. * We also do not want to hold onto application's * old data for too long. Interactive applications * would rather discard old data. */ if (tp->t_rttcur <= (basertt + 25)) { 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; } } else { so->so_snd.sb_idealsize = max(tcp_sendspace, so->so_snd.sb_hiwat - (2 * tcp_autosndbuf_inc)); so->so_snd.sb_flags |= SB_TRIM; } } } /* * 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, * ipfw rules 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 && ip_use_randomid && kipf_count == 0 && dlil_filter_disable_tso_count == 0 && tp->rcv_numsacks == 0 && sack_rxmit == 0 && sack_bytes_rxmt == 0 && inp->inp_options == NULL && inp->in6p_options == NULL #if IPSEC && ipsec_optlen == 0 #endif #if IPFIREWALL && (fw_enable == 0 || fw_bypass) #endif ) { tso = 1; sendalot = 0; } else { len = tp->t_maxseg; sendalot = 1; 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) && !(tp->t_mpflags & TMPF_TCP_FALLBACK)) { int newlen = len; if (!(tp->t_mpflags & TMPF_PREESTABLISHED) && (tp->t_state > TCPS_CLOSED) && ((tp->t_mpflags & TMPF_SND_MPPRIO) || (tp->t_mpflags & TMPF_SND_REM_ADDR) || (tp->t_mpflags & TMPF_SND_MPFAIL))) { if (len > 0) { len = 0; } 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) newlen = mptcp_adj_sendlen(so, off, len); if (newlen < len) { len = newlen; sendalot = 1; } } #endif /* MPTCP */ /* * If the socket is capable of doing unordered send, * pull the amount of data that can be sent from the * unordered priority queues to the serial queue in * the socket buffer. If bytes are not yet available * in the highest priority message, we may not be able * to send any new data. */ if (so->so_flags & SOF_ENABLE_MSGS) { if ((off + len) > so->so_msg_state->msg_serial_bytes) { sbpull_unordered_data(so, off, len); /* check if len needs to be modified */ if ((off + len) > so->so_msg_state->msg_serial_bytes) { len = so->so_msg_state->msg_serial_bytes - off; if (len <= 0) { len = 0; tcpstat.tcps_msg_sndwaithipri++; } } } } if (sack_rxmit) { 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; } recwin = tcp_sbspace(tp); /* * 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)) goto send; if (sack_rxmit) 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 (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) goto send; if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) goto send; } else { tcpstat.tcps_fcholdpacket++; } } /* * 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. * Skip this if the connection is in T/TCP half-open state. */ if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN)) { /* * "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 (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 (!(tp->t_flags & TF_STRETCHACK) && (tp->last_ack_sent != tp->rcv_nxt || ((oldwin + adv) >> tp->rcv_scale) > (oldwin >> tp->rcv_scale))) { goto send; } /* * Make sure that the delayed ack timer is set if * we delayed sending a window update because of * streaming detection. */ if ((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); } } if (4 * adv >= (int32_t) so->so_rcv.sb_hiwat) goto send; } /* * 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) goto send; if ((flags & TH_RST) || ((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0)) 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) { tp->t_rxtshift = 0; tp->t_rxtstart = 0; 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), (sack_rxmit | (sack_bytes_rxmt != 0)), recwin, #if INET6 isipv6); #else /* INET6 */ 0); #endif /* !INET6 */ } /* 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) { if (len >= tp->t_maxseg) tp->t_flags |= TF_MAXSEGSNT; else tp->t_flags &= ~TF_MAXSEGSNT; } /* * 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 INET6 if (isipv6) hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr); else #endif hdrlen = sizeof (struct tcpiphdr); if (flags & TH_SYN) { tp->snd_nxt = 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) { optlen = mptcp_setup_syn_opts(so, flags, opt, optlen); } #endif /* MPTCP */ } } /* * 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 */ if ((tcp_ecn_inbound || (tp->t_flags & TF_ENABLE_ECN)) && (flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK)) { if ((tp->ecn_flags & TE_SETUPRECEIVED) != 0) { if ((tp->ecn_flags & TE_SETUPSENT) == 0) { /* 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_setup++; } else { /* * 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. */ tp->ecn_flags &= ~TE_SETUPRECEIVED; /* * We already incremented the counter * assuming that the ECN setup will * succeed. Decrementing here to * correct it. */ tcpstat.tcps_ecn_setup--; } } } else if ((tcp_ecn_outbound || (tp->t_flags & TF_ENABLE_ECN)) && (flags & (TH_SYN | TH_ACK)) == TH_SYN) { if ((tp->ecn_flags & TE_SETUPSENT) == 0) { /* 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); } else { /* * We sent an ECN-setup SYN but it was dropped. * Fall back to no ECN and clear flag indicating * we should send data with IP ECT set. */ tp->ecn_flags &= ~TE_SENDIPECT; } } /* * 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) && !sack_rxmit) { flags |= TH_CWR; tp->ecn_flags &= ~TE_SENDCWR; tcpstat.tcps_sent_cwr++; } /* * Check if we should set the TCP ECE flag. */ if ((tp->ecn_flags & TE_SENDECE) != 0 && len == 0) { flags |= TH_ECE; tcpstat.tcps_sent_ece++; } /* * 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); *lp = htonl(tp->ts_recent); optlen += TCPOLEN_TSTAMP_APPA; } /* Note the timestamp for receive buffer autosizing */ if (tp->rfbuf_ts == 0 && (so->so_rcv.sb_flags & SB_AUTOSIZE)) tp->rfbuf_ts = tcp_now; 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, &dlenp, &finp, &dss_val, &sseqp, &mptcp_acknow); tp->t_mpflags &= ~TMPF_SEND_DSN; } #endif /* MPTCP */ 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 && MAX_TCPOPTLEN - optlen - 2 >= TCPOLEN_SACK) { int nsack, padlen; u_char *bp = (u_char *)opt + optlen; u_int32_t *lp; nsack = (MAX_TCPOPTLEN - optlen - 2) / TCPOLEN_SACK; nsack = min(nsack, tp->rcv_numsacks); sackoptlen = (2 + nsack * TCPOLEN_SACK); /* * 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++ = sackoptlen; lp = (u_int32_t *)(void *)bp; for (i = 0; i < nsack; i++) { struct sackblk sack = tp->sackblks[i]; *lp++ = htonl(sack.start); *lp++ = htonl(sack.end); } optlen += sackoptlen; } } /* 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--; } } hdrlen += optlen; #if INET6 if (isipv6) ipoptlen = ip6_optlen(inp); else #endif { 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; if (len > tso_maxlen - hdrlen - optlen) { len = tso_maxlen - hdrlen - optlen; len = len - (len % (tp->t_maxopd - optlen)); sendalot = 1; } else if (tp->t_flags & TF_NEEDFIN) { sendalot = 1; } } else { len = tp->t_maxopd - optlen - ipoptlen; sendalot = 1; } } #if MPTCP /* Adjust the length in the DSS option, if it is lesser than len */ if (dlenp) { /* * To test this path without SACK, artificially * decrement len with something like * if (len > 10) len -= 10; */ if (ntohs(*dlenp) > len) { *dlenp = htons(len); /* Unset the FIN flag, if len was adjusted */ if (finp) { *finp &= ~MDSS_F; } sendalot = 1; } } #endif /* MPTCP */ if (max_linkhdr + hdrlen > MCLBYTES) panic("tcphdr too big"); /* Check if there is enough data in the send socket * buffer to start measuring bw */ if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 && (tp->t_bwmeas != NULL) && (tp->t_flagsext & TF_BWMEAS_INPROGRESS) == 0 && (so->so_snd.sb_cc - (tp->snd_max - tp->snd_una)) >= tp->t_bwmeas->bw_minsize) { tp->t_bwmeas->bw_size = min( (so->so_snd.sb_cc - (tp->snd_max - tp->snd_una)), tp->t_bwmeas->bw_maxsize); tp->t_flagsext |= TF_BWMEAS_INPROGRESS; tp->t_bwmeas->bw_start = tp->snd_max; tp->t_bwmeas->bw_ts = tcp_now; } 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) { if ((tp->t_flagsext & TF_FORCE) && len == 1) tcpstat.tcps_sndprobe++; else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || 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, cell, wifi, wired, txpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, txbytes, len); tp->t_stat.txretransmitbytes += len; } } else { tcpstat.tcps_sndpack++; tcpstat.tcps_sndbyte += len; if (nstat_collect) { INP_ADD_STAT(inp, cell, wifi, wired, txpackets, 1); INP_ADD_STAT(inp, cell, wifi, wired, txbytes, len); } } #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) { m->m_next = m_copym_mode(so->so_snd.sb_mb, off, (int)len, M_DONTWAIT, 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 ((m = m_copym_with_hdrs(so->so_snd.sb_mb, off, len, M_DONTWAIT, NULL, NULL, copymode)) == 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.) */ if (off + len == so->so_snd.sb_cc) 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; #if MPTCP /* Before opt is copied to the mbuf, set the csum field */ mptcp_output_csum(tp, m, len, hdrlen, dss_val, sseqp); #endif /* MPTCP */ #if CONFIG_MACF_NET mac_mbuf_label_associate_inpcb(inp, m); #endif #if INET6 if (isipv6) { ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(void *)(ip6 + 1); tcp_fillheaders(tp, ip6, th); if ((tp->ecn_flags & TE_SENDIPECT) != 0 && len && !SEQ_LT(tp->snd_nxt, tp->snd_max) && !sack_rxmit) { ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); } svc_flags |= PKT_SCF_IPV6; #if PF_ECN m->m_pkthdr.pf_mtag.pftag_hdr = (void *)ip6; m->m_pkthdr.pf_mtag.pftag_flags |= PF_TAG_HDR_INET6; #endif /* PF_ECN */ } else #endif /* INET6 */ { ip = mtod(m, struct ip *); ipov = (struct ipovly *)ip; th = (struct tcphdr *)(void *)(ip + 1); /* this picks up the pseudo header (w/o the length) */ tcp_fillheaders(tp, ip, th); if ((tp->ecn_flags & TE_SENDIPECT) != 0 && len && !SEQ_LT(tp->snd_nxt, tp->snd_max) && !sack_rxmit) { ip->ip_tos = IPTOS_ECN_ECT0; } #if PF_ECN m->m_pkthdr.pf_mtag.pftag_hdr = (void *)ip; m->m_pkthdr.pf_mtag.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...) */ if (sack_rxmit == 0) { if (len || (flags & (TH_SYN|TH_FIN)) || tp->t_timer[TCPT_PERSIST]) th->th_seq = htonl(tp->snd_nxt); else th->th_seq = htonl(tp->snd_max); } else { th->th_seq = htonl(p->rxmit); p->rxmit += len; tp->sackhint.sack_bytes_rexmit += len; } th->th_ack = htonl(tp->rcv_nxt); tp->last_ack_sent = tp->rcv_nxt; #if MPTCP /* Initialize the ACK field to a value as 0 ack fields are dropped */ if (early_data_sent) { th->th_ack = th->th_seq + 1; } #endif /* MPTCP */ if (optlen) { bcopy(opt, th + 1, optlen); th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; } th->th_flags = flags; /* * Calculate receive window. Don't shrink window, * but avoid silly window syndrome. */ if (recwin < (int32_t)(so->so_rcv.sb_hiwat / 4) && recwin < (int)tp->t_maxseg) recwin = 0; if (recwin < (int32_t)(tp->rcv_adv - tp->rcv_nxt)) recwin = (int32_t)(tp->rcv_adv - tp->rcv_nxt); if (tp->t_flags & TF_SLOWLINK && slowlink_wsize > 0) { if (recwin > (int32_t)slowlink_wsize) recwin = slowlink_wsize; } #if TRAFFIC_MGT if (tcp_recv_bg == 1 || IS_TCP_RECV_BG(so)) { if (tcp_recv_throttle(tp)) { uint32_t min_iaj_win = tcp_min_iaj_win * tp->t_maxseg; if (tp->iaj_rwintop == 0 || SEQ_LT(tp->iaj_rwintop, tp->rcv_adv)) tp->iaj_rwintop = tp->rcv_adv; if (SEQ_LT(tp->iaj_rwintop, tp->rcv_nxt + min_iaj_win)) tp->iaj_rwintop = tp->rcv_nxt + min_iaj_win; recwin = min(tp->iaj_rwintop - tp->rcv_nxt, recwin); } } #endif /* TRAFFIC_MGT */ if (recwin > (int32_t)(TCP_MAXWIN << tp->rcv_scale)) recwin = (int32_t)(TCP_MAXWIN << tp->rcv_scale); th->th_win = htons((u_short) (recwin>>tp->rcv_scale)); /* * 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 INET6 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 #endif /* INET6 */ { 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 INET6 if (isipv6) m->m_pkthdr.csum_flags |= CSUM_TSO_IPV6; else #endif /* INET6 */ 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 (sack_rxmit) goto timer; tp->snd_nxt += len; if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { tp->snd_max = tp->snd_nxt; /* * Time this transmission if not a retransmission and * not currently timing anything. */ if (tp->t_rtttime == 0) { tp->t_rtttime = tcp_now; tp->t_rtseq = startseq; tcpstat.tcps_segstimed++; } } /* * 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 && ((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_rxtshift = 0; tp->t_rxtstart = 0; tp->t_persist_stop = 0; } 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 && 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) { u_int32_t pto, srtt, new_rto = 0; /* * Using SRTT alone to set PTO can cause spurious * retransmissions on wireless networks where there * is a lot of variance in RTT. Taking variance * into account will avoid this. */ srtt = tp->t_srtt >> TCP_RTT_SHIFT; pto = ((TCP_REXMTVAL(tp)) * 3) >> 1; pto = max (2 * srtt, pto); if ((tp->snd_max - tp->snd_una) == tp->t_maxseg) pto = max(pto, (((3 * pto) >> 2) + tcp_delack * 2)); else pto = max(10, pto); /* if RTO is less than PTO, choose RTO instead */ if (tp->t_rxtcur < pto) { /* * Schedule PTO instead of RTO in favor of * fast recovery. */ pto = tp->t_rxtcur; /* Reset the next RTO to be after PTO. */ TCPT_RANGESET(new_rto, (pto + TCP_REXMTVAL(tp)), max(tp->t_rttmin, tp->t_rttcur + 2), TCPTV_REXMTMAX, 0); tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, new_rto); } 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; } #if TCPDEBUG /* * Trace. */ if (so_options & SO_DEBUG) tcp_trace(TA_OUTPUT, tp->t_state, tp, mtod(m, void *), th, 0); #endif /* * 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. */ #if INET6 /* * 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); /* TODO: IPv6 IP6TOS_ECT bit on */ 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 #endif /* INET6 */ { ip->ip_len = m->m_pkthdr.len; ip->ip_ttl = inp->inp_ip_ttl; /* XXX */ ip->ip_tos |= (inp->inp_ip_tos & ~IPTOS_ECN_MASK);/* XXX */ 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 INET6 if (!isipv6) #endif /* INET6 */ if (path_mtu_discovery && (tp->t_flags & TF_PMTUD)) ip->ip_off |= IP_DF; #if NECP { necp_kernel_policy_id policy_id; if (!necp_socket_is_allowed_to_send_recv(inp, &policy_id)) { m_freem(m); error = EHOSTUNREACH; goto out; } necp_mark_packet_from_socket(m, inp, policy_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; #if MPTCP /* Disable flow advisory when using MPTCP. */ if (!(tp->t_mpflags & TMPF_MPTCP_TRUE)) #endif /* MPTCP */ m->m_pkthdr.pkt_flags |= PKTF_FLOW_ADV; m->m_pkthdr.pkt_proto = IPPROTO_TCP; 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 (tcp_prioritize_acks != 0 && len == 0 && (inp->inp_last_outifp->if_eflags & (IFEF_TXSTART | IFEF_NOACKPRI)) == IFEF_TXSTART && th->th_flags == TH_ACK && tp->snd_una == tp->snd_max && tp->t_timer[TCPT_REXMT] == 0) { svc_flags |= PKT_SCF_TCP_ACK; } set_packet_service_class(m, so, MBUF_SC_UNSPEC, svc_flags); } tp->t_pktlist_sentlen += len; tp->t_lastchain++; #if INET6 if (isipv6) { DTRACE_TCP5(send, struct mbuf *, m, struct inpcb *, inp, struct ip6 *, ip6, struct tcpcb *, tp, struct tcphdr *, th); } else #endif /* INET6 */ { 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; } if ((lro_ackmore) && (!sackoptlen) && (!tp->t_timer[TCPT_PERSIST]) && ((th->th_flags & TH_ACK) == TH_ACK) && (!len) && (tp->t_state == TCPS_ESTABLISHED)) { /* For a pure ACK, see if you need to send more of them */ mnext = tcp_send_lroacks(tp, m, th); if (mnext) { tp->t_pktlist_tail->m_nextpkt = mnext; if (mnext->m_nextpkt == NULL) { tp->t_pktlist_tail = mnext; tp->t_lastchain++; } else { struct mbuf *tail, *next; next = mnext->m_nextpkt; tail = next->m_nextpkt; while (tail) { next = tail; tail = tail->m_nextpkt; tp->t_lastchain++; } tp->t_pktlist_tail = next; } } } if (sendalot == 0 || (tp->t_state != TCPS_ESTABLISHED) || (tp->snd_cwnd <= (tp->snd_wnd / 8)) || (tp->t_flags & (TH_PUSH | 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), (sack_rxmit | (sack_bytes_rxmt != 0)), recwin, #if INET6 isipv6); #else /* INET6 */ 0); #endif /* !INET6 */ 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) { if (sack_rxmit) { if (SEQ_GT((p->rxmit - lost), tp->snd_una)) { p->rxmit -= lost; } else { lost = p->rxmit - tp->snd_una; p->rxmit = tp->snd_una; } tp->sackhint.sack_bytes_rexmit -= lost; } 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) { if (!tp->t_timer[TCPT_REXMT] && !tp->t_timer[TCPT_PERSIST]) 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_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); 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 as a soft error. */ if ((error == EHOSTUNREACH || error == ENETDOWN) && TCPS_HAVERCVDSYN(tp->t_state) && !inp_restricted_send(inp, inp->inp_last_outifp)) { tp->t_softerror = error; error = 0; } 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, int recwin, boolean_t isipv6) { int error = 0; boolean_t chain; boolean_t unlocked = FALSE; boolean_t ifdenied = FALSE; struct inpcb *inp = tp->t_inpcb; struct ip_out_args ipoa = { IFSCOPE_NONE, { 0 }, IPOAF_SELECT_SRCIF|IPOAF_BOUND_SRCADDR, 0 }; struct route ro; struct ifnet *outif = NULL; #if INET6 struct ip6_out_args ip6oa = { IFSCOPE_NONE, { 0 }, IP6OAF_SELECT_SRCIF|IP6OAF_BOUND_SRCADDR, 0 }; struct route_in6 ro6; struct flowadv *adv = (isipv6 ? &ip6oa.ip6oa_flowadv : &ipoa.ipoa_flowadv); #else /* INET6 */ struct flowadv *adv = &ipoa.ipoa_flowadv; #endif /* !INET6 */ /* If socket was bound to an ifindex, tell ip_output about it */ if (inp->inp_flags & INP_BOUND_IF) { #if INET6 if (isipv6) { ip6oa.ip6oa_boundif = inp->inp_boundifp->if_index; ip6oa.ip6oa_flags |= IP6OAF_BOUND_IF; } else #endif /* INET6 */ { ipoa.ipoa_boundif = inp->inp_boundifp->if_index; ipoa.ipoa_flags |= IPOAF_BOUND_IF; } } if (INP_NO_CELLULAR(inp)) { #if INET6 if (isipv6) ip6oa.ip6oa_flags |= IP6OAF_NO_CELLULAR; else #endif /* INET6 */ ipoa.ipoa_flags |= IPOAF_NO_CELLULAR; } if (INP_NO_EXPENSIVE(inp)) { #if INET6 if (isipv6) ip6oa.ip6oa_flags |= IP6OAF_NO_EXPENSIVE; else #endif /* INET6 */ ipoa.ipoa_flags |= IPOAF_NO_EXPENSIVE; } if (INP_AWDL_UNRESTRICTED(inp)) { #if INET6 if (isipv6) ip6oa.ip6oa_flags |= IP6OAF_AWDL_UNRESTRICTED; else #endif /* INET6 */ ipoa.ipoa_flags |= IPOAF_AWDL_UNRESTRICTED; } #if INET6 if (isipv6) flags |= IPV6_OUTARGS; else #endif /* INET6 */ flags |= IP_OUTARGS; /* Copy the cached route and take an extra reference */ #if INET6 if (isipv6) in6p_route_copyout(inp, &ro6); else #endif /* INET6 */ inp_route_copyout(inp, &ro); /* * Data sent (as far as we can tell). * If this advertises a larger window than any other segment, * then remember the size of the advertised window. * Make sure ACK/DELACK conditions are cleared before * we unlock the socket. */ if (recwin > 0 && SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv)) tp->rcv_adv = tp->rcv_nxt + recwin; tp->last_ack_sent = tp->rcv_nxt; tp->t_flags &= ~(TF_ACKNOW | TF_DELACK); tp->t_timer[TCPT_DELACK] = 0; tp->t_unacksegs = 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)) { 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 #if IPFIREWALL && (fw_enable == 0 || fw_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 INET6 if (isipv6) { error = ip6_output_list(pkt, cnt, inp->in6p_outputopts, &ro6, flags, NULL, NULL, &ip6oa); ifdenied = (ip6oa.ip6oa_retflags & IP6OARF_IFDENIED); } else { #endif /* INET6 */ error = ip_output_list(pkt, cnt, opt, &ro, flags, NULL, &ipoa); ifdenied = (ipoa.ipoa_retflags & IPOARF_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. * * 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) { 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)); } /* * 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 INET6 if (isipv6) { if (ro6.ro_rt != NULL && (outif = ro6.ro_rt->rt_ifp) != inp->in6p_last_outifp) inp->in6p_last_outifp = outif; } else #endif /* INET6 */ if (ro.ro_rt != NULL && (outif = ro.ro_rt->rt_ifp) != inp->inp_last_outifp) inp->inp_last_outifp = outif; if (error != 0 && ifdenied && (INP_NO_CELLULAR(inp) || INP_NO_EXPENSIVE(inp))) soevent(inp->inp_socket, (SO_FILT_HINT_LOCKED|SO_FILT_HINT_IFDENIED)); /* Synchronize cached PCB route & options */ #if INET6 if (isipv6) in6p_route_copyin(inp, &ro6); else #endif /* INET6 */ 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); } void tcp_setpersist(tp) register 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, 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++; } /* * Send as many acks as data coalesced. Every other packet when stretch * ACK is not enabled. Every 8 packets, if stretch ACK is enabled. */ static struct mbuf* tcp_send_lroacks(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th) { struct mbuf *mnext = NULL, *ack_chain = NULL, *tail = NULL; int count = 0; tcp_seq org_ack = ntohl(th->th_ack); tcp_seq prev_ack = 0; int tack_offset = 28; /* XXX IPv6 and IP options not supported */ int twin_offset = 34; /* XXX IPv6 and IP options not supported */ int ack_size = (tp->t_flags & TF_STRETCHACK) ? (maxseg_unacked * tp->t_maxseg) : (tp->t_maxseg << 1); int segs_acked = (tp->t_flags & TF_STRETCHACK) ? maxseg_unacked : 2; struct mbuf *prev_ack_pkt = NULL; struct socket *so = tp->t_inpcb->inp_socket; unsigned short winsz = ntohs(th->th_win); unsigned int scaled_win = winsz<rcv_scale; tcp_seq win_rtedge = org_ack + scaled_win; count = tp->t_lropktlen/tp->t_maxseg; prev_ack = (org_ack - tp->t_lropktlen) + ack_size; if (prev_ack < org_ack) { ack_chain = m_dup(m, M_DONTWAIT); if (ack_chain) { th->th_ack = htonl(prev_ack); /* Keep adv window constant for duplicated ACK packets */ scaled_win = win_rtedge - prev_ack; if (scaled_win > (int32_t)(TCP_MAXWIN << tp->rcv_scale)) scaled_win = (int32_t)(TCP_MAXWIN << tp->rcv_scale); th->th_win = htons(scaled_win>>tp->rcv_scale); if (lrodebug == 5) { printf("%s: win = %d winsz = %d sc = %d" " lro_len %d %d\n", __func__, scaled_win>>tp->rcv_scale, winsz, tp->rcv_scale, tp->t_lropktlen, count); } tail = ack_chain; count -= segs_acked; /* accounts for prev_ack packet */ count = (count <= segs_acked) ? 0 : count - segs_acked; tcpstat.tcps_sndacks++; so_tc_update_stats(m, so, m_get_service_class(m)); } else { return NULL; } } else { tp->t_lropktlen = 0; return NULL; } prev_ack_pkt = ack_chain; while (count > 0) { if ((prev_ack + ack_size) < org_ack) { prev_ack += ack_size; } else { /* * The last ACK sent must have the ACK number that TCP * thinks is the last sent ACK number. */ prev_ack = org_ack; } mnext = m_dup(prev_ack_pkt, M_DONTWAIT); if (mnext) { /* Keep adv window constant for duplicated ACK packets */ scaled_win = win_rtedge - prev_ack; if (scaled_win > (int32_t)(TCP_MAXWIN << tp->rcv_scale)) scaled_win = (int32_t)(TCP_MAXWIN << tp->rcv_scale); winsz = htons(scaled_win>>tp->rcv_scale); if (lrodebug == 5) { printf("%s: winsz = %d ack %x count %d\n", __func__, scaled_win>>tp->rcv_scale, prev_ack, count); } bcopy(&winsz, mtod(prev_ack_pkt, caddr_t) + twin_offset, 2); HTONL(prev_ack); bcopy(&prev_ack, mtod(prev_ack_pkt, caddr_t) + tack_offset, 4); NTOHL(prev_ack); tail->m_nextpkt = mnext; tail = mnext; count -= segs_acked; tcpstat.tcps_sndacks++; so_tc_update_stats(m, so, m_get_service_class(m)); } else { if (lrodebug == 5) { printf("%s: failed to alloc mbuf.\n", __func__); } break; } prev_ack_pkt = mnext; } tp->t_lropktlen = 0; return ack_chain; } static int tcp_recv_throttle (struct tcpcb *tp) { uint32_t base_rtt, newsize; int32_t qdelay; struct sockbuf *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) { qdelay = tp->t_rttcur - base_rtt; /* * if latency increased on a background flow, * return 1 to start throttling. */ if (qdelay > target_qdelay) { tp->t_flagsext |= TF_RECV_THROTTLE; /* * 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); }