9ec4a4cca5
long been superseded by the RFC3390 initial CWND sizing. Also remove the remnants of TCP_METRICS_CWND which used the TCP hostcache to set the initial CWND in a non-RFC compliant way. MFC after: 1 week
1509 lines
43 KiB
C
1509 lines
43 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_output.c 8.4 (Berkeley) 5/24/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_ipsec.h"
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#include "opt_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/domain.h>
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#include <sys/hhook.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mbuf.h>
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#include <sys/mutex.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <net/vnet.h>
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#include <netinet/cc.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip_options.h>
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#ifdef INET6
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#include <netinet6/in6_pcb.h>
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#include <netinet/ip6.h>
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#include <netinet6/ip6_var.h>
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#endif
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#define TCPOUTFLAGS
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet/tcpip.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif
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#ifdef IPSEC
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#include <netipsec/ipsec.h>
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#endif /*IPSEC*/
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#include <machine/in_cksum.h>
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#include <security/mac/mac_framework.h>
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VNET_DEFINE(int, path_mtu_discovery) = 1;
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SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_RW,
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&VNET_NAME(path_mtu_discovery), 1,
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"Enable Path MTU Discovery");
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|
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VNET_DEFINE(int, tcp_do_tso) = 1;
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#define V_tcp_do_tso VNET(tcp_do_tso)
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SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_RW,
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&VNET_NAME(tcp_do_tso), 0,
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"Enable TCP Segmentation Offload");
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VNET_DEFINE(int, tcp_do_autosndbuf) = 1;
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#define V_tcp_do_autosndbuf VNET(tcp_do_autosndbuf)
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SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_auto, CTLFLAG_RW,
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&VNET_NAME(tcp_do_autosndbuf), 0,
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"Enable automatic send buffer sizing");
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VNET_DEFINE(int, tcp_autosndbuf_inc) = 8*1024;
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#define V_tcp_autosndbuf_inc VNET(tcp_autosndbuf_inc)
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SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_inc, CTLFLAG_RW,
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&VNET_NAME(tcp_autosndbuf_inc), 0,
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"Incrementor step size of automatic send buffer");
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VNET_DEFINE(int, tcp_autosndbuf_max) = 2*1024*1024;
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#define V_tcp_autosndbuf_max VNET(tcp_autosndbuf_max)
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SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_max, CTLFLAG_RW,
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&VNET_NAME(tcp_autosndbuf_max), 0,
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"Max size of automatic send buffer");
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|
|
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static void inline hhook_run_tcp_est_out(struct tcpcb *tp,
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struct tcphdr *th, struct tcpopt *to,
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long len, int tso);
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static void inline cc_after_idle(struct tcpcb *tp);
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/*
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* Wrapper for the TCP established ouput helper hook.
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*/
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static void inline
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hhook_run_tcp_est_out(struct tcpcb *tp, struct tcphdr *th,
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struct tcpopt *to, long len, int tso)
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{
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struct tcp_hhook_data hhook_data;
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|
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|
if (V_tcp_hhh[HHOOK_TCP_EST_OUT]->hhh_nhooks > 0) {
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hhook_data.tp = tp;
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hhook_data.th = th;
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hhook_data.to = to;
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hhook_data.len = len;
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hhook_data.tso = tso;
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|
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|
hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_OUT], &hhook_data,
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tp->osd);
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}
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}
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|
|
/*
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* CC wrapper hook functions
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*/
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static void inline
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cc_after_idle(struct tcpcb *tp)
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{
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INP_WLOCK_ASSERT(tp->t_inpcb);
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|
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if (CC_ALGO(tp)->after_idle != NULL)
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CC_ALGO(tp)->after_idle(tp->ccv);
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}
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|
|
|
/*
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* Tcp output routine: figure out what should be sent and send it.
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*/
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int
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tcp_output(struct tcpcb *tp)
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{
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struct socket *so = tp->t_inpcb->inp_socket;
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long len, recwin, sendwin;
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int off, flags, error = 0; /* Keep compiler happy */
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struct mbuf *m;
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struct ip *ip = NULL;
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struct ipovly *ipov = NULL;
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struct tcphdr *th;
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u_char opt[TCP_MAXOLEN];
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unsigned ipoptlen, optlen, hdrlen;
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#ifdef IPSEC
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unsigned ipsec_optlen = 0;
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#endif
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int idle, sendalot;
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int sack_rxmit, sack_bytes_rxmt;
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struct sackhole *p;
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int tso;
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struct tcpopt to;
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#if 0
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int maxburst = TCP_MAXBURST;
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#endif
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#ifdef INET6
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struct ip6_hdr *ip6 = NULL;
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int isipv6;
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|
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isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) != 0;
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#endif
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|
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INP_WLOCK_ASSERT(tp->t_inpcb);
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|
|
|
/*
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* Determine length of data that should be transmitted,
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* and flags that will be used.
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* If there is some data or critical controls (SYN, RST)
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* to send, then transmit; otherwise, investigate further.
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*/
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idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una);
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if (idle && ticks - tp->t_rcvtime >= tp->t_rxtcur)
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cc_after_idle(tp);
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tp->t_flags &= ~TF_LASTIDLE;
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if (idle) {
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if (tp->t_flags & TF_MORETOCOME) {
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tp->t_flags |= TF_LASTIDLE;
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idle = 0;
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}
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}
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again:
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/*
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* If we've recently taken a timeout, snd_max will be greater than
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* snd_nxt. There may be SACK information that allows us to avoid
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* resending already delivered data. Adjust snd_nxt accordingly.
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*/
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if ((tp->t_flags & TF_SACK_PERMIT) &&
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SEQ_LT(tp->snd_nxt, tp->snd_max))
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tcp_sack_adjust(tp);
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sendalot = 0;
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tso = 0;
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off = tp->snd_nxt - tp->snd_una;
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sendwin = min(tp->snd_wnd, tp->snd_cwnd);
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flags = tcp_outflags[tp->t_state];
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/*
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* Send any SACK-generated retransmissions. If we're explicitly trying
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* to send out new data (when sendalot is 1), bypass this function.
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* If we retransmit in fast recovery mode, decrement snd_cwnd, since
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* we're replacing a (future) new transmission with a retransmission
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* now, and we previously incremented snd_cwnd in tcp_input().
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*/
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/*
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* Still in sack recovery , reset rxmit flag to zero.
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*/
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sack_rxmit = 0;
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sack_bytes_rxmt = 0;
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len = 0;
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p = NULL;
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if ((tp->t_flags & TF_SACK_PERMIT) && IN_FASTRECOVERY(tp->t_flags) &&
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(p = tcp_sack_output(tp, &sack_bytes_rxmt))) {
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long cwin;
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cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt;
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if (cwin < 0)
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cwin = 0;
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/* Do not retransmit SACK segments beyond snd_recover */
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if (SEQ_GT(p->end, tp->snd_recover)) {
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/*
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* (At least) part of sack hole extends beyond
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* snd_recover. Check to see if we can rexmit data
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* for this hole.
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*/
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if (SEQ_GEQ(p->rxmit, tp->snd_recover)) {
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/*
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* Can't rexmit any more data for this hole.
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* That data will be rexmitted in the next
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* sack recovery episode, when snd_recover
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* moves past p->rxmit.
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*/
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p = NULL;
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goto after_sack_rexmit;
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} else
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/* Can rexmit part of the current hole */
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len = ((long)ulmin(cwin,
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tp->snd_recover - p->rxmit));
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} else
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len = ((long)ulmin(cwin, p->end - p->rxmit));
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off = p->rxmit - tp->snd_una;
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KASSERT(off >= 0,("%s: sack block to the left of una : %d",
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__func__, off));
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if (len > 0) {
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sack_rxmit = 1;
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sendalot = 1;
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TCPSTAT_INC(tcps_sack_rexmits);
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TCPSTAT_ADD(tcps_sack_rexmit_bytes,
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min(len, tp->t_maxseg));
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}
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}
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after_sack_rexmit:
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/*
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* Get standard flags, and add SYN or FIN if requested by 'hidden'
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* state flags.
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*/
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if (tp->t_flags & TF_NEEDFIN)
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flags |= TH_FIN;
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if (tp->t_flags & TF_NEEDSYN)
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flags |= TH_SYN;
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SOCKBUF_LOCK(&so->so_snd);
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/*
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* If in persist timeout with window of 0, send 1 byte.
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* Otherwise, if window is small but nonzero
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* and timer expired, we will send what we can
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* and go to transmit state.
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*/
|
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if (tp->t_flags & TF_FORCEDATA) {
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if (sendwin == 0) {
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/*
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* If we still have some data to send, then
|
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* clear the FIN bit. Usually this would
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* happen below when it realizes that we
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* aren't sending all the data. However,
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* if we have exactly 1 byte of unsent data,
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* then it won't clear the FIN bit below,
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* and if we are in persist state, we wind
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* up sending the packet without recording
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* that we sent the FIN bit.
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*
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* We can't just blindly clear the FIN bit,
|
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* because if we don't have any more data
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* to send then the probe will be the FIN
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* itself.
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*/
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if (off < so->so_snd.sb_cc)
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flags &= ~TH_FIN;
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sendwin = 1;
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} else {
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tcp_timer_activate(tp, TT_PERSIST, 0);
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tp->t_rxtshift = 0;
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}
|
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}
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|
|
/*
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* If snd_nxt == snd_max and we have transmitted a FIN, the
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* offset will be > 0 even if so_snd.sb_cc is 0, resulting in
|
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* a negative length. This can also occur when TCP opens up
|
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* its congestion window while receiving additional duplicate
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* acks after fast-retransmit because TCP will reset snd_nxt
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* to snd_max after the fast-retransmit.
|
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*
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* In the normal retransmit-FIN-only case, however, snd_nxt will
|
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* be set to snd_una, the offset will be 0, and the length may
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* wind up 0.
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*
|
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* If sack_rxmit is true we are retransmitting from the scoreboard
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* in which case len is already set.
|
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*/
|
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if (sack_rxmit == 0) {
|
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if (sack_bytes_rxmt == 0)
|
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len = ((long)ulmin(so->so_snd.sb_cc, sendwin) - off);
|
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else {
|
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long cwin;
|
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|
|
/*
|
|
* We are inside of a SACK recovery episode and are
|
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* sending new data, having retransmitted all the
|
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* data possible in the scoreboard.
|
|
*/
|
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len = ((long)ulmin(so->so_snd.sb_cc, tp->snd_wnd)
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- off);
|
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/*
|
|
* Don't remove this (len > 0) check !
|
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* We explicitly check for len > 0 here (although it
|
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* isn't really necessary), to work around a gcc
|
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* optimization issue - to force gcc to compute
|
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* len above. Without this check, the computation
|
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* of len is bungled by the optimizer.
|
|
*/
|
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if (len > 0) {
|
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cwin = tp->snd_cwnd -
|
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(tp->snd_nxt - tp->sack_newdata) -
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sack_bytes_rxmt;
|
|
if (cwin < 0)
|
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cwin = 0;
|
|
len = lmin(len, cwin);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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++;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
if (len < 0) {
|
|
/*
|
|
* 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) {
|
|
tcp_timer_activate(tp, TT_REXMT, 0);
|
|
tp->t_rxtshift = 0;
|
|
tp->snd_nxt = tp->snd_una;
|
|
if (!tcp_timer_active(tp, TT_PERSIST))
|
|
tcp_setpersist(tp);
|
|
}
|
|
}
|
|
|
|
/* len will be >= 0 after this point. */
|
|
KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__));
|
|
|
|
/*
|
|
* Automatic sizing of send socket buffer. Often the send buffer
|
|
* size is not optimally adjusted to the actual network conditions
|
|
* at hand (delay bandwidth product). Setting the buffer size too
|
|
* small limits throughput on links with high bandwidth and high
|
|
* delay (eg. trans-continental/oceanic links). Setting the
|
|
* buffer size too big consumes too much real kernel memory,
|
|
* especially with many connections on busy servers.
|
|
*
|
|
* The criteria to step up the send buffer one notch are:
|
|
* 1. receive window of remote host is larger than send buffer
|
|
* (with a fudge factor of 5/4th);
|
|
* 2. send buffer is filled to 7/8th with data (so we actually
|
|
* have data to make use of it);
|
|
* 3. send buffer fill has not hit maximal automatic size;
|
|
* 4. our send window (slow start and cogestion controlled) is
|
|
* larger than sent but unacknowledged data in send buffer.
|
|
*
|
|
* The remote host receive window scaling factor may limit the
|
|
* growing of the send buffer before it reaches its allowed
|
|
* maximum.
|
|
*
|
|
* It scales directly with slow start or congestion window
|
|
* and does at most one step per received ACK. This fast
|
|
* scaling has the drawback of growing the send buffer beyond
|
|
* what is strictly necessary to make full use of a given
|
|
* delay*bandwith product. However testing has shown this not
|
|
* to be much of an problem. At worst we are trading wasting
|
|
* of available bandwith (the non-use of it) for wasting some
|
|
* socket buffer memory.
|
|
*
|
|
* TODO: Shrink send buffer during idle periods together
|
|
* with congestion window. Requires another timer. Has to
|
|
* wait for upcoming tcp timer rewrite.
|
|
*/
|
|
if (V_tcp_do_autosndbuf && so->so_snd.sb_flags & 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) &&
|
|
so->so_snd.sb_cc < V_tcp_autosndbuf_max &&
|
|
sendwin >= (so->so_snd.sb_cc - (tp->snd_nxt - tp->snd_una))) {
|
|
if (!sbreserve_locked(&so->so_snd,
|
|
min(so->so_snd.sb_hiwat + V_tcp_autosndbuf_inc,
|
|
V_tcp_autosndbuf_max), so, curthread))
|
|
so->so_snd.sb_flags &= ~SB_AUTOSIZE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Decide if we can use TCP Segmentation Offloading (if supported by
|
|
* hardware).
|
|
*
|
|
* TSO may only be used if we are in a pure bulk sending state. The
|
|
* presence of TCP-MD5, SACK retransmits, SACK advertizements and
|
|
* IP options 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.
|
|
*/
|
|
#ifdef IPSEC
|
|
/*
|
|
* Pre-calculate here as we save another lookup into the darknesses
|
|
* of IPsec that way and can actually decide if TSO is ok.
|
|
*/
|
|
ipsec_optlen = ipsec_hdrsiz_tcp(tp);
|
|
#endif
|
|
if ((tp->t_flags & TF_TSO) && V_tcp_do_tso && len > tp->t_maxseg &&
|
|
((tp->t_flags & TF_SIGNATURE) == 0) &&
|
|
tp->rcv_numsacks == 0 && sack_rxmit == 0 &&
|
|
#ifdef IPSEC
|
|
ipsec_optlen == 0 &&
|
|
#endif
|
|
tp->t_inpcb->inp_options == NULL &&
|
|
tp->t_inpcb->in6p_options == NULL)
|
|
tso = 1;
|
|
|
|
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 = sbspace(&so->so_rcv);
|
|
|
|
/*
|
|
* Sender silly window avoidance. We transmit under the following
|
|
* conditions when len is non-zero:
|
|
*
|
|
* - 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've timed out (e.g. persist timer)
|
|
* - we have more then 1/2 the maximum send window's worth of
|
|
* data (receiver may be limited the window size)
|
|
* - we need to retransmit
|
|
*/
|
|
if (len) {
|
|
if (len >= tp->t_maxseg)
|
|
goto send;
|
|
/*
|
|
* NOTE! on localhost connections an 'ack' from the remote
|
|
* end may occur synchronously with the output and cause
|
|
* us to flush a buffer queued with moretocome. XXX
|
|
*
|
|
* note: the len + off check is almost certainly unnecessary.
|
|
*/
|
|
if (!(tp->t_flags & TF_MORETOCOME) && /* normal case */
|
|
(idle || (tp->t_flags & TF_NODELAY)) &&
|
|
len + off >= so->so_snd.sb_cc &&
|
|
(tp->t_flags & TF_NOPUSH) == 0) {
|
|
goto send;
|
|
}
|
|
if (tp->t_flags & TF_FORCEDATA) /* typ. timeout case */
|
|
goto send;
|
|
if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0)
|
|
goto send;
|
|
if (SEQ_LT(tp->snd_nxt, tp->snd_max)) /* retransmit case */
|
|
goto send;
|
|
if (sack_rxmit)
|
|
goto send;
|
|
}
|
|
|
|
/*
|
|
* 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 50% 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.
|
|
* Don't send pure window updates when the peer has closed
|
|
* the connection and won't ever send more data.
|
|
*/
|
|
if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN) &&
|
|
!TCPS_HAVERCVDFIN(tp->t_state)) {
|
|
/*
|
|
* "adv" is the amount we can increase the window,
|
|
* taking into account that we are limited by
|
|
* TCP_MAXWIN << tp->rcv_scale.
|
|
*/
|
|
long adv;
|
|
int oldwin;
|
|
|
|
adv = min(recwin, (long)TCP_MAXWIN << tp->rcv_scale);
|
|
if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) {
|
|
oldwin = (tp->rcv_adv - tp->rcv_nxt);
|
|
adv -= oldwin;
|
|
} else
|
|
oldwin = 0;
|
|
|
|
/*
|
|
* If the new window size ends up being the same as the old
|
|
* size when it is scaled, then don't force a window update.
|
|
*/
|
|
if (oldwin >> tp->rcv_scale == (adv + oldwin) >> tp->rcv_scale)
|
|
goto dontupdate;
|
|
if (adv >= (long) (2 * tp->t_maxseg))
|
|
goto send;
|
|
if (2 * adv >= (long) so->so_rcv.sb_hiwat)
|
|
goto send;
|
|
}
|
|
dontupdate:
|
|
|
|
/*
|
|
* 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 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) == 0 || 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 ((tp->t_flags & TF_SACK_PERMIT) &&
|
|
SEQ_GT(tp->snd_max, tp->snd_una) &&
|
|
!tcp_timer_active(tp, TT_REXMT) &&
|
|
!tcp_timer_active(tp, TT_PERSIST)) {
|
|
tcp_timer_activate(tp, TT_REXMT, 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
|
|
*
|
|
* tcp_timer_active(tp, TT_PERSIST)
|
|
* is true when we are in persist state.
|
|
* (tp->t_flags & TF_FORCEDATA)
|
|
* is set when we are called to send a persist packet.
|
|
* tcp_timer_active(tp, TT_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 && !tcp_timer_active(tp, TT_REXMT) &&
|
|
!tcp_timer_active(tp, TT_PERSIST)) {
|
|
tp->t_rxtshift = 0;
|
|
tcp_setpersist(tp);
|
|
}
|
|
|
|
/*
|
|
* No reason to send a segment, just return.
|
|
*/
|
|
just_return:
|
|
SOCKBUF_UNLOCK(&so->so_snd);
|
|
return (0);
|
|
|
|
send:
|
|
SOCKBUF_LOCK_ASSERT(&so->so_snd);
|
|
/*
|
|
* 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;
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
|
|
else
|
|
#endif
|
|
hdrlen = sizeof (struct tcpiphdr);
|
|
|
|
/*
|
|
* Compute options for segment.
|
|
* We only have to care about SYN and established connection
|
|
* segments. Options for SYN-ACK segments are handled in TCP
|
|
* syncache.
|
|
*/
|
|
if ((tp->t_flags & TF_NOOPT) == 0) {
|
|
to.to_flags = 0;
|
|
/* Maximum segment size. */
|
|
if (flags & TH_SYN) {
|
|
tp->snd_nxt = tp->iss;
|
|
to.to_mss = tcp_mssopt(&tp->t_inpcb->inp_inc);
|
|
to.to_flags |= TOF_MSS;
|
|
}
|
|
/* Window scaling. */
|
|
if ((flags & TH_SYN) && (tp->t_flags & TF_REQ_SCALE)) {
|
|
to.to_wscale = tp->request_r_scale;
|
|
to.to_flags |= TOF_SCALE;
|
|
}
|
|
/* Timestamps. */
|
|
if ((tp->t_flags & TF_RCVD_TSTMP) ||
|
|
((flags & TH_SYN) && (tp->t_flags & TF_REQ_TSTMP))) {
|
|
to.to_tsval = ticks + tp->ts_offset;
|
|
to.to_tsecr = tp->ts_recent;
|
|
to.to_flags |= TOF_TS;
|
|
/* Set receive buffer autosizing timestamp. */
|
|
if (tp->rfbuf_ts == 0 &&
|
|
(so->so_rcv.sb_flags & SB_AUTOSIZE))
|
|
tp->rfbuf_ts = ticks;
|
|
}
|
|
/* Selective ACK's. */
|
|
if (tp->t_flags & TF_SACK_PERMIT) {
|
|
if (flags & TH_SYN)
|
|
to.to_flags |= TOF_SACKPERM;
|
|
else if (TCPS_HAVEESTABLISHED(tp->t_state) &&
|
|
(tp->t_flags & TF_SACK_PERMIT) &&
|
|
tp->rcv_numsacks > 0) {
|
|
to.to_flags |= TOF_SACK;
|
|
to.to_nsacks = tp->rcv_numsacks;
|
|
to.to_sacks = (u_char *)tp->sackblks;
|
|
}
|
|
}
|
|
#ifdef TCP_SIGNATURE
|
|
/* TCP-MD5 (RFC2385). */
|
|
if (tp->t_flags & TF_SIGNATURE)
|
|
to.to_flags |= TOF_SIGNATURE;
|
|
#endif /* TCP_SIGNATURE */
|
|
|
|
/* Processing the options. */
|
|
hdrlen += optlen = tcp_addoptions(&to, opt);
|
|
}
|
|
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
ipoptlen = ip6_optlen(tp->t_inpcb);
|
|
else
|
|
#endif
|
|
if (tp->t_inpcb->inp_options)
|
|
ipoptlen = tp->t_inpcb->inp_options->m_len -
|
|
offsetof(struct ipoption, ipopt_list);
|
|
else
|
|
ipoptlen = 0;
|
|
#ifdef 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.
|
|
*/
|
|
if (len + optlen + ipoptlen > tp->t_maxopd) {
|
|
flags &= ~TH_FIN;
|
|
|
|
if (tso) {
|
|
KASSERT(ipoptlen == 0,
|
|
("%s: TSO can't do IP options", __func__));
|
|
|
|
/*
|
|
* Limit a burst to IP_MAXPACKET minus IP,
|
|
* TCP and options length to keep ip->ip_len
|
|
* from overflowing.
|
|
*/
|
|
if (len > IP_MAXPACKET - hdrlen) {
|
|
len = IP_MAXPACKET - hdrlen;
|
|
sendalot = 1;
|
|
}
|
|
|
|
/*
|
|
* Prevent the last segment from being
|
|
* fractional unless the send sockbuf can
|
|
* be emptied.
|
|
*/
|
|
if (sendalot && off + len < so->so_snd.sb_cc) {
|
|
len -= len % (tp->t_maxopd - optlen);
|
|
sendalot = 1;
|
|
}
|
|
|
|
/*
|
|
* Send the FIN in a separate segment
|
|
* after the bulk sending is done.
|
|
* We don't trust the TSO implementations
|
|
* to clear the FIN flag on all but the
|
|
* last segment.
|
|
*/
|
|
if (tp->t_flags & TF_NEEDFIN)
|
|
sendalot = 1;
|
|
|
|
} else {
|
|
len = tp->t_maxopd - optlen - ipoptlen;
|
|
sendalot = 1;
|
|
}
|
|
} else
|
|
tso = 0;
|
|
|
|
KASSERT(len + hdrlen + ipoptlen <= IP_MAXPACKET,
|
|
("%s: len > IP_MAXPACKET", __func__));
|
|
|
|
/*#ifdef DIAGNOSTIC*/
|
|
#ifdef INET6
|
|
if (max_linkhdr + hdrlen > MCLBYTES)
|
|
#else
|
|
if (max_linkhdr + hdrlen > MHLEN)
|
|
#endif
|
|
panic("tcphdr too big");
|
|
/*#endif*/
|
|
|
|
/*
|
|
* This KASSERT is here to catch edge cases at a well defined place.
|
|
* Before, those had triggered (random) panic conditions further down.
|
|
*/
|
|
KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__));
|
|
|
|
/*
|
|
* 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) {
|
|
struct mbuf *mb;
|
|
u_int moff;
|
|
|
|
if ((tp->t_flags & TF_FORCEDATA) && len == 1)
|
|
TCPSTAT_INC(tcps_sndprobe);
|
|
else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || sack_rxmit) {
|
|
tp->t_sndrexmitpack++;
|
|
TCPSTAT_INC(tcps_sndrexmitpack);
|
|
TCPSTAT_ADD(tcps_sndrexmitbyte, len);
|
|
} else {
|
|
TCPSTAT_INC(tcps_sndpack);
|
|
TCPSTAT_ADD(tcps_sndbyte, len);
|
|
}
|
|
MGETHDR(m, M_DONTWAIT, MT_DATA);
|
|
if (m == NULL) {
|
|
SOCKBUF_UNLOCK(&so->so_snd);
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
#ifdef INET6
|
|
if (MHLEN < hdrlen + max_linkhdr) {
|
|
MCLGET(m, M_DONTWAIT);
|
|
if ((m->m_flags & M_EXT) == 0) {
|
|
SOCKBUF_UNLOCK(&so->so_snd);
|
|
m_freem(m);
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
}
|
|
#endif
|
|
m->m_data += max_linkhdr;
|
|
m->m_len = hdrlen;
|
|
|
|
/*
|
|
* Start the m_copy functions from the closest mbuf
|
|
* to the offset in the socket buffer chain.
|
|
*/
|
|
mb = sbsndptr(&so->so_snd, off, len, &moff);
|
|
|
|
if (len <= MHLEN - hdrlen - max_linkhdr) {
|
|
m_copydata(mb, moff, (int)len,
|
|
mtod(m, caddr_t) + hdrlen);
|
|
m->m_len += len;
|
|
} else {
|
|
m->m_next = m_copy(mb, moff, (int)len);
|
|
if (m->m_next == NULL) {
|
|
SOCKBUF_UNLOCK(&so->so_snd);
|
|
(void) m_free(m);
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
SOCKBUF_UNLOCK(&so->so_snd);
|
|
} else {
|
|
SOCKBUF_UNLOCK(&so->so_snd);
|
|
if (tp->t_flags & TF_ACKNOW)
|
|
TCPSTAT_INC(tcps_sndacks);
|
|
else if (flags & (TH_SYN|TH_FIN|TH_RST))
|
|
TCPSTAT_INC(tcps_sndctrl);
|
|
else if (SEQ_GT(tp->snd_up, tp->snd_una))
|
|
TCPSTAT_INC(tcps_sndurg);
|
|
else
|
|
TCPSTAT_INC(tcps_sndwinup);
|
|
|
|
MGETHDR(m, M_DONTWAIT, MT_DATA);
|
|
if (m == NULL) {
|
|
error = ENOBUFS;
|
|
goto out;
|
|
}
|
|
#ifdef INET6
|
|
if (isipv6 && (MHLEN < hdrlen + max_linkhdr) &&
|
|
MHLEN >= hdrlen) {
|
|
MH_ALIGN(m, hdrlen);
|
|
} else
|
|
#endif
|
|
m->m_data += max_linkhdr;
|
|
m->m_len = hdrlen;
|
|
}
|
|
SOCKBUF_UNLOCK_ASSERT(&so->so_snd);
|
|
m->m_pkthdr.rcvif = (struct ifnet *)0;
|
|
#ifdef MAC
|
|
mac_inpcb_create_mbuf(tp->t_inpcb, m);
|
|
#endif
|
|
#ifdef INET6
|
|
if (isipv6) {
|
|
ip6 = mtod(m, struct ip6_hdr *);
|
|
th = (struct tcphdr *)(ip6 + 1);
|
|
tcpip_fillheaders(tp->t_inpcb, ip6, th);
|
|
} else
|
|
#endif /* INET6 */
|
|
{
|
|
ip = mtod(m, struct ip *);
|
|
ipov = (struct ipovly *)ip;
|
|
th = (struct tcphdr *)(ip + 1);
|
|
tcpip_fillheaders(tp->t_inpcb, ip, th);
|
|
}
|
|
|
|
/*
|
|
* 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 starting a connection, send ECN setup
|
|
* SYN packet. If we are on a retransmit, we may
|
|
* resend those bits a number of times as per
|
|
* RFC 3168.
|
|
*/
|
|
if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) {
|
|
if (tp->t_rxtshift >= 1) {
|
|
if (tp->t_rxtshift <= V_tcp_ecn_maxretries)
|
|
flags |= TH_ECE|TH_CWR;
|
|
} else
|
|
flags |= TH_ECE|TH_CWR;
|
|
}
|
|
|
|
if (tp->t_state == TCPS_ESTABLISHED &&
|
|
(tp->t_flags & TF_ECN_PERMIT)) {
|
|
/*
|
|
* If the peer has ECN, mark data packets with
|
|
* ECN capable transmission (ECT).
|
|
* Ignore pure ack packets, retransmissions and window probes.
|
|
*/
|
|
if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) &&
|
|
!((tp->t_flags & TF_FORCEDATA) && len == 1)) {
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20);
|
|
else
|
|
#endif
|
|
ip->ip_tos |= IPTOS_ECN_ECT0;
|
|
TCPSTAT_INC(tcps_ecn_ect0);
|
|
}
|
|
|
|
/*
|
|
* Reply with proper ECN notifications.
|
|
*/
|
|
if (tp->t_flags & TF_ECN_SND_CWR) {
|
|
flags |= TH_CWR;
|
|
tp->t_flags &= ~TF_ECN_SND_CWR;
|
|
}
|
|
if (tp->t_flags & TF_ECN_SND_ECE)
|
|
flags |= TH_ECE;
|
|
}
|
|
|
|
/*
|
|
* 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)) ||
|
|
tcp_timer_active(tp, TT_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);
|
|
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 < (long)(so->so_rcv.sb_hiwat / 4) &&
|
|
recwin < (long)tp->t_maxseg)
|
|
recwin = 0;
|
|
if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) &&
|
|
recwin < (long)(tp->rcv_adv - tp->rcv_nxt))
|
|
recwin = (long)(tp->rcv_adv - tp->rcv_nxt);
|
|
if (recwin > (long)TCP_MAXWIN << tp->rcv_scale)
|
|
recwin = (long)TCP_MAXWIN << tp->rcv_scale;
|
|
|
|
/*
|
|
* According to RFC1323 the window field in a SYN (i.e., a <SYN>
|
|
* or <SYN,ACK>) segment itself is never scaled. The <SYN,ACK>
|
|
* case is handled in syncache.
|
|
*/
|
|
if (flags & TH_SYN)
|
|
th->th_win = htons((u_short)
|
|
(min(sbspace(&so->so_rcv), TCP_MAXWIN)));
|
|
else
|
|
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 than can be buffered prior to transmitting on
|
|
* the connection.
|
|
*/
|
|
if (th->th_win == 0) {
|
|
tp->t_sndzerowin++;
|
|
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 */
|
|
|
|
#ifdef TCP_SIGNATURE
|
|
if (tp->t_flags & TF_SIGNATURE) {
|
|
int sigoff = to.to_signature - opt;
|
|
tcp_signature_compute(m, 0, len, optlen,
|
|
(u_char *)(th + 1) + sigoff, IPSEC_DIR_OUTBOUND);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Put TCP length in extended header, and then
|
|
* checksum extended header and data.
|
|
*/
|
|
m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */
|
|
#ifdef INET6
|
|
if (isipv6)
|
|
/*
|
|
* ip6_plen is not need to be filled now, and will be filled
|
|
* in ip6_output.
|
|
*/
|
|
th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(struct ip6_hdr),
|
|
sizeof(struct tcphdr) + optlen + len);
|
|
else
|
|
#endif /* INET6 */
|
|
{
|
|
m->m_pkthdr.csum_flags = CSUM_TCP;
|
|
m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
|
|
th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
|
|
htons(sizeof(struct tcphdr) + IPPROTO_TCP + len + optlen));
|
|
|
|
/* IP version must be set here for ipv4/ipv6 checking later */
|
|
KASSERT(ip->ip_v == IPVERSION,
|
|
("%s: IP version incorrect: %d", __func__, ip->ip_v));
|
|
}
|
|
|
|
/*
|
|
* Enable TSO and specify the size of the segments.
|
|
* The TCP pseudo header checksum is always provided.
|
|
* XXX: Fixme: This is currently not the case for IPv6.
|
|
*/
|
|
if (tso) {
|
|
KASSERT(len > tp->t_maxopd - optlen,
|
|
("%s: len <= tso_segsz", __func__));
|
|
m->m_pkthdr.csum_flags |= CSUM_TSO;
|
|
m->m_pkthdr.tso_segsz = tp->t_maxopd - optlen;
|
|
}
|
|
|
|
#ifdef IPSEC
|
|
KASSERT(len + hdrlen + ipoptlen - ipsec_optlen == m_length(m, NULL),
|
|
("%s: mbuf chain shorter than expected: %ld + %u + %u - %u != %u",
|
|
__func__, len, hdrlen, ipoptlen, ipsec_optlen, m_length(m, NULL)));
|
|
#else
|
|
KASSERT(len + hdrlen + ipoptlen == m_length(m, NULL),
|
|
("%s: mbuf chain shorter than expected: %ld + %u + %u != %u",
|
|
__func__, len, hdrlen, ipoptlen, m_length(m, NULL)));
|
|
#endif
|
|
|
|
/*
|
|
* In transmit state, time the transmission and arrange for
|
|
* the retransmit. In persist state, just set snd_max.
|
|
*/
|
|
if ((tp->t_flags & TF_FORCEDATA) == 0 ||
|
|
!tcp_timer_active(tp, TT_PERSIST)) {
|
|
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->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 = ticks;
|
|
tp->t_rtseq = startseq;
|
|
TCPSTAT_INC(tcps_segstimed);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Set retransmit timer if not currently set,
|
|
* and not doing a pure ack or a keep-alive probe.
|
|
* Initial value for retransmit timer is smoothed
|
|
* round-trip time + 2 * round-trip time variance.
|
|
* Initialize shift counter which is used for backoff
|
|
* of retransmit time.
|
|
*/
|
|
timer:
|
|
if (!tcp_timer_active(tp, TT_REXMT) &&
|
|
((sack_rxmit && tp->snd_nxt != tp->snd_max) ||
|
|
(tp->snd_nxt != tp->snd_una))) {
|
|
if (tcp_timer_active(tp, TT_PERSIST)) {
|
|
tcp_timer_activate(tp, TT_PERSIST, 0);
|
|
tp->t_rxtshift = 0;
|
|
}
|
|
tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur);
|
|
}
|
|
} 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) {
|
|
++xlen;
|
|
tp->t_flags |= TF_SENTFIN;
|
|
}
|
|
if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max))
|
|
tp->snd_max = tp->snd_nxt + len;
|
|
}
|
|
|
|
/* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */
|
|
hhook_run_tcp_est_out(tp, th, &to, len, tso);
|
|
|
|
#ifdef TCPDEBUG
|
|
/*
|
|
* Trace.
|
|
*/
|
|
if (so->so_options & SO_DEBUG) {
|
|
u_short save = 0;
|
|
#ifdef INET6
|
|
if (!isipv6)
|
|
#endif
|
|
{
|
|
save = ipov->ih_len;
|
|
ipov->ih_len = htons(m->m_pkthdr.len /* - hdrlen + (th->th_off << 2) */);
|
|
}
|
|
tcp_trace(TA_OUTPUT, tp->t_state, tp, mtod(m, void *), th, 0);
|
|
#ifdef INET6
|
|
if (!isipv6)
|
|
#endif
|
|
ipov->ih_len = save;
|
|
}
|
|
#endif /* TCPDEBUG */
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
#ifdef INET6
|
|
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(tp->t_inpcb, NULL);
|
|
|
|
/* TODO: IPv6 IP6TOS_ECT bit on */
|
|
error = ip6_output(m,
|
|
tp->t_inpcb->in6p_outputopts, NULL,
|
|
((so->so_options & SO_DONTROUTE) ?
|
|
IP_ROUTETOIF : 0), NULL, NULL, tp->t_inpcb);
|
|
}
|
|
#endif /* INET6 */
|
|
#if defined(INET) && defined(INET6)
|
|
else
|
|
#endif
|
|
#ifdef INET
|
|
{
|
|
ip->ip_len = m->m_pkthdr.len;
|
|
#ifdef INET6
|
|
if (tp->t_inpcb->inp_vflag & INP_IPV6PROTO)
|
|
ip->ip_ttl = in6_selecthlim(tp->t_inpcb, NULL);
|
|
#endif /* INET6 */
|
|
/*
|
|
* If we do path MTU discovery, then we set DF on every packet.
|
|
* This might not be the best thing to do according to RFC3390
|
|
* Section 2. However the tcp hostcache migitates the problem
|
|
* so it affects only the first tcp connection with a host.
|
|
*
|
|
* NB: Don't set DF on small MTU/MSS to have a safe fallback.
|
|
*/
|
|
if (V_path_mtu_discovery && tp->t_maxopd > V_tcp_minmss)
|
|
ip->ip_off |= IP_DF;
|
|
|
|
error = ip_output(m, tp->t_inpcb->inp_options, NULL,
|
|
((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 0,
|
|
tp->t_inpcb);
|
|
}
|
|
#endif /* INET */
|
|
if (error) {
|
|
|
|
/*
|
|
* We know that the packet was lost, so back out the
|
|
* sequence number advance, if any.
|
|
*
|
|
* If the error is EPERM the packet got blocked by the
|
|
* local firewall. Normally we should terminate the
|
|
* connection but the blocking may have been spurious
|
|
* due to a firewall reconfiguration cycle. So we treat
|
|
* it like a packet loss and let the retransmit timer and
|
|
* timeouts do their work over time.
|
|
* XXX: It is a POLA question whether calling tcp_drop right
|
|
* away would be the really correct behavior instead.
|
|
*/
|
|
if (((tp->t_flags & TF_FORCEDATA) == 0 ||
|
|
!tcp_timer_active(tp, TT_PERSIST)) &&
|
|
((flags & TH_SYN) == 0) &&
|
|
(error != EPERM)) {
|
|
if (sack_rxmit) {
|
|
p->rxmit -= len;
|
|
tp->sackhint.sack_bytes_rexmit -= len;
|
|
KASSERT(tp->sackhint.sack_bytes_rexmit >= 0,
|
|
("sackhint bytes rtx >= 0"));
|
|
} else
|
|
tp->snd_nxt -= len;
|
|
}
|
|
out:
|
|
SOCKBUF_UNLOCK_ASSERT(&so->so_snd); /* Check gotos. */
|
|
switch (error) {
|
|
case EPERM:
|
|
tp->t_softerror = error;
|
|
return (error);
|
|
case ENOBUFS:
|
|
if (!tcp_timer_active(tp, TT_REXMT) &&
|
|
!tcp_timer_active(tp, TT_PERSIST))
|
|
tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur);
|
|
tp->snd_cwnd = tp->t_maxseg;
|
|
return (0);
|
|
case EMSGSIZE:
|
|
/*
|
|
* For some reason the interface we used initially
|
|
* to send segments changed to another or lowered
|
|
* its MTU.
|
|
*
|
|
* tcp_mtudisc() will find out the new MTU and 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(tp->t_inpcb, 0);
|
|
return (0);
|
|
case EHOSTDOWN:
|
|
case EHOSTUNREACH:
|
|
case ENETDOWN:
|
|
case ENETUNREACH:
|
|
if (TCPS_HAVERCVDSYN(tp->t_state)) {
|
|
tp->t_softerror = error;
|
|
return (0);
|
|
}
|
|
/* FALLTHROUGH */
|
|
default:
|
|
return (error);
|
|
}
|
|
}
|
|
TCPSTAT_INC(tcps_sndtotal);
|
|
|
|
/*
|
|
* 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.
|
|
* Any pending ACK has now been sent.
|
|
*/
|
|
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);
|
|
if (tcp_timer_active(tp, TT_DELACK))
|
|
tcp_timer_activate(tp, TT_DELACK, 0);
|
|
#if 0
|
|
/*
|
|
* This completely breaks TCP if newreno is turned on. What happens
|
|
* is that if delayed-acks are turned on on the receiver, this code
|
|
* on the transmitter effectively destroys the TCP window, forcing
|
|
* it to four packets (1.5Kx4 = 6K window).
|
|
*/
|
|
if (sendalot && --maxburst)
|
|
goto again;
|
|
#endif
|
|
if (sendalot)
|
|
goto again;
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
tcp_setpersist(struct tcpcb *tp)
|
|
{
|
|
int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1;
|
|
int tt;
|
|
|
|
tp->t_flags &= ~TF_PREVVALID;
|
|
if (tcp_timer_active(tp, TT_REXMT))
|
|
panic("tcp_setpersist: retransmit pending");
|
|
/*
|
|
* Start/restart persistance timer.
|
|
*/
|
|
TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift],
|
|
TCPTV_PERSMIN, TCPTV_PERSMAX);
|
|
tcp_timer_activate(tp, TT_PERSIST, tt);
|
|
if (tp->t_rxtshift < TCP_MAXRXTSHIFT)
|
|
tp->t_rxtshift++;
|
|
}
|
|
|
|
/*
|
|
* Insert TCP options according to the supplied parameters to the place
|
|
* optp in a consistent way. Can handle unaligned destinations.
|
|
*
|
|
* The order of the option processing is crucial for optimal packing and
|
|
* alignment for the scarce option space.
|
|
*
|
|
* The optimal order for a SYN/SYN-ACK segment is:
|
|
* MSS (4) + NOP (1) + Window scale (3) + SACK permitted (2) +
|
|
* Timestamp (10) + Signature (18) = 38 bytes out of a maximum of 40.
|
|
*
|
|
* The SACK options should be last. SACK blocks consume 8*n+2 bytes.
|
|
* So a full size SACK blocks option is 34 bytes (with 4 SACK blocks).
|
|
* At minimum we need 10 bytes (to generate 1 SACK block). If both
|
|
* TCP Timestamps (12 bytes) and TCP Signatures (18 bytes) are present,
|
|
* we only have 10 bytes for SACK options (40 - (12 + 18)).
|
|
*/
|
|
int
|
|
tcp_addoptions(struct tcpopt *to, u_char *optp)
|
|
{
|
|
u_int mask, optlen = 0;
|
|
|
|
for (mask = 1; mask < TOF_MAXOPT; mask <<= 1) {
|
|
if ((to->to_flags & mask) != mask)
|
|
continue;
|
|
if (optlen == TCP_MAXOLEN)
|
|
break;
|
|
switch (to->to_flags & mask) {
|
|
case TOF_MSS:
|
|
while (optlen % 4) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
if (TCP_MAXOLEN - optlen < TCPOLEN_MAXSEG)
|
|
continue;
|
|
optlen += TCPOLEN_MAXSEG;
|
|
*optp++ = TCPOPT_MAXSEG;
|
|
*optp++ = TCPOLEN_MAXSEG;
|
|
to->to_mss = htons(to->to_mss);
|
|
bcopy((u_char *)&to->to_mss, optp, sizeof(to->to_mss));
|
|
optp += sizeof(to->to_mss);
|
|
break;
|
|
case TOF_SCALE:
|
|
while (!optlen || optlen % 2 != 1) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
if (TCP_MAXOLEN - optlen < TCPOLEN_WINDOW)
|
|
continue;
|
|
optlen += TCPOLEN_WINDOW;
|
|
*optp++ = TCPOPT_WINDOW;
|
|
*optp++ = TCPOLEN_WINDOW;
|
|
*optp++ = to->to_wscale;
|
|
break;
|
|
case TOF_SACKPERM:
|
|
while (optlen % 2) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
if (TCP_MAXOLEN - optlen < TCPOLEN_SACK_PERMITTED)
|
|
continue;
|
|
optlen += TCPOLEN_SACK_PERMITTED;
|
|
*optp++ = TCPOPT_SACK_PERMITTED;
|
|
*optp++ = TCPOLEN_SACK_PERMITTED;
|
|
break;
|
|
case TOF_TS:
|
|
while (!optlen || optlen % 4 != 2) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
if (TCP_MAXOLEN - optlen < TCPOLEN_TIMESTAMP)
|
|
continue;
|
|
optlen += TCPOLEN_TIMESTAMP;
|
|
*optp++ = TCPOPT_TIMESTAMP;
|
|
*optp++ = TCPOLEN_TIMESTAMP;
|
|
to->to_tsval = htonl(to->to_tsval);
|
|
to->to_tsecr = htonl(to->to_tsecr);
|
|
bcopy((u_char *)&to->to_tsval, optp, sizeof(to->to_tsval));
|
|
optp += sizeof(to->to_tsval);
|
|
bcopy((u_char *)&to->to_tsecr, optp, sizeof(to->to_tsecr));
|
|
optp += sizeof(to->to_tsecr);
|
|
break;
|
|
case TOF_SIGNATURE:
|
|
{
|
|
int siglen = TCPOLEN_SIGNATURE - 2;
|
|
|
|
while (!optlen || optlen % 4 != 2) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
if (TCP_MAXOLEN - optlen < TCPOLEN_SIGNATURE)
|
|
continue;
|
|
optlen += TCPOLEN_SIGNATURE;
|
|
*optp++ = TCPOPT_SIGNATURE;
|
|
*optp++ = TCPOLEN_SIGNATURE;
|
|
to->to_signature = optp;
|
|
while (siglen--)
|
|
*optp++ = 0;
|
|
break;
|
|
}
|
|
case TOF_SACK:
|
|
{
|
|
int sackblks = 0;
|
|
struct sackblk *sack = (struct sackblk *)to->to_sacks;
|
|
tcp_seq sack_seq;
|
|
|
|
while (!optlen || optlen % 4 != 2) {
|
|
optlen += TCPOLEN_NOP;
|
|
*optp++ = TCPOPT_NOP;
|
|
}
|
|
if (TCP_MAXOLEN - optlen < TCPOLEN_SACKHDR + TCPOLEN_SACK)
|
|
continue;
|
|
optlen += TCPOLEN_SACKHDR;
|
|
*optp++ = TCPOPT_SACK;
|
|
sackblks = min(to->to_nsacks,
|
|
(TCP_MAXOLEN - optlen) / TCPOLEN_SACK);
|
|
*optp++ = TCPOLEN_SACKHDR + sackblks * TCPOLEN_SACK;
|
|
while (sackblks--) {
|
|
sack_seq = htonl(sack->start);
|
|
bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq));
|
|
optp += sizeof(sack_seq);
|
|
sack_seq = htonl(sack->end);
|
|
bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq));
|
|
optp += sizeof(sack_seq);
|
|
optlen += TCPOLEN_SACK;
|
|
sack++;
|
|
}
|
|
TCPSTAT_INC(tcps_sack_send_blocks);
|
|
break;
|
|
}
|
|
default:
|
|
panic("%s: unknown TCP option type", __func__);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Terminate and pad TCP options to a 4 byte boundary. */
|
|
if (optlen % 4) {
|
|
optlen += TCPOLEN_EOL;
|
|
*optp++ = TCPOPT_EOL;
|
|
}
|
|
/*
|
|
* According to RFC 793 (STD0007):
|
|
* "The content of the header beyond the End-of-Option option
|
|
* must be header padding (i.e., zero)."
|
|
* and later: "The padding is composed of zeros."
|
|
*/
|
|
while (optlen % 4) {
|
|
optlen += TCPOLEN_PAD;
|
|
*optp++ = TCPOPT_PAD;
|
|
}
|
|
|
|
KASSERT(optlen <= TCP_MAXOLEN, ("%s: TCP options too long", __func__));
|
|
return (optlen);
|
|
}
|