There should be no functional changes with this commit. Reviewed by: rscheff Differential revision: https://reviews.freebsd.org/D37123
1075 lines
32 KiB
C
1075 lines
32 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California.
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* 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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* 3. 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_sack.c 8.12 (Berkeley) 5/24/95
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*/
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/*-
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* @@(#)COPYRIGHT 1.1 (NRL) 17 January 1995
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*
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* NRL grants permission for redistribution and use in source and binary
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* forms, with or without modification, of the software and documentation
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* created at NRL provided that the following conditions are met:
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*
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgements:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* This product includes software developed at the Information
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* Technology Division, US Naval Research Laboratory.
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* 4. Neither the name of the NRL 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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* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
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* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* The views and conclusions contained in the software and documentation
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* are those of the authors and should not be interpreted as representing
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* official policies, either expressed or implied, of the US Naval
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* Research Laboratory (NRL).
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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_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/proc.h> /* for proc0 declaration */
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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/syslog.h>
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#include <sys/systm.h>
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#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
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#include <vm/uma.h>
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#include <net/if.h>
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#include <net/if_var.h>
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#include <net/route.h>
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#include <net/vnet.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_var.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/ip6.h>
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#include <netinet/icmp6.h>
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#include <netinet6/nd6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet/tcp.h>
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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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#include <netinet/cc/cc.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif /* TCPDEBUG */
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#include <machine/in_cksum.h>
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VNET_DECLARE(struct uma_zone *, sack_hole_zone);
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#define V_sack_hole_zone VNET(sack_hole_zone)
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SYSCTL_NODE(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
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"TCP SACK");
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VNET_DEFINE(int, tcp_do_sack) = 1;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
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&VNET_NAME(tcp_do_sack), 0,
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"Enable/Disable TCP SACK support");
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VNET_DEFINE(int, tcp_do_newsack) = 1;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, revised, CTLFLAG_VNET | CTLFLAG_RW,
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&VNET_NAME(tcp_do_newsack), 0,
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"Use revised SACK loss recovery per RFC 6675");
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VNET_DEFINE(int, tcp_sack_maxholes) = 128;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, maxholes, CTLFLAG_VNET | CTLFLAG_RW,
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&VNET_NAME(tcp_sack_maxholes), 0,
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"Maximum number of TCP SACK holes allowed per connection");
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VNET_DEFINE(int, tcp_sack_globalmaxholes) = 65536;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalmaxholes, CTLFLAG_VNET | CTLFLAG_RW,
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&VNET_NAME(tcp_sack_globalmaxholes), 0,
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"Global maximum number of TCP SACK holes");
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VNET_DEFINE(int, tcp_sack_globalholes) = 0;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalholes, CTLFLAG_VNET | CTLFLAG_RD,
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&VNET_NAME(tcp_sack_globalholes), 0,
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"Global number of TCP SACK holes currently allocated");
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int
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tcp_dsack_block_exists(struct tcpcb *tp)
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{
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/* Return true if a DSACK block exists */
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if (tp->rcv_numsacks == 0)
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return (0);
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if (SEQ_LEQ(tp->sackblks[0].end, tp->rcv_nxt))
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return(1);
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return (0);
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}
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/*
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* This function will find overlaps with the currently stored sackblocks
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* and add any overlap as a dsack block upfront
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*/
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void
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tcp_update_dsack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
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{
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struct sackblk head_blk,mid_blk,saved_blks[MAX_SACK_BLKS];
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int i, j, n, identical;
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tcp_seq start, end;
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INP_WLOCK_ASSERT(tptoinpcb(tp));
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KASSERT(SEQ_LT(rcv_start, rcv_end), ("rcv_start < rcv_end"));
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if (SEQ_LT(rcv_end, tp->rcv_nxt) ||
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((rcv_end == tp->rcv_nxt) &&
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(tp->rcv_numsacks > 0 ) &&
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(tp->sackblks[0].end == tp->rcv_nxt))) {
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saved_blks[0].start = rcv_start;
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saved_blks[0].end = rcv_end;
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} else {
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saved_blks[0].start = saved_blks[0].end = 0;
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}
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head_blk.start = head_blk.end = 0;
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mid_blk.start = rcv_start;
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mid_blk.end = rcv_end;
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identical = 0;
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for (i = 0; i < tp->rcv_numsacks; i++) {
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start = tp->sackblks[i].start;
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end = tp->sackblks[i].end;
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if (SEQ_LT(rcv_end, start)) {
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/* pkt left to sack blk */
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continue;
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}
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if (SEQ_GT(rcv_start, end)) {
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/* pkt right to sack blk */
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continue;
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}
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if (SEQ_GT(tp->rcv_nxt, end)) {
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if ((SEQ_MAX(rcv_start, start) != SEQ_MIN(rcv_end, end)) &&
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(SEQ_GT(head_blk.start, SEQ_MAX(rcv_start, start)) ||
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(head_blk.start == head_blk.end))) {
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head_blk.start = SEQ_MAX(rcv_start, start);
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head_blk.end = SEQ_MIN(rcv_end, end);
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}
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continue;
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}
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if (((head_blk.start == head_blk.end) ||
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SEQ_LT(start, head_blk.start)) &&
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(SEQ_GT(end, rcv_start) &&
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SEQ_LEQ(start, rcv_end))) {
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head_blk.start = start;
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head_blk.end = end;
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}
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mid_blk.start = SEQ_MIN(mid_blk.start, start);
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mid_blk.end = SEQ_MAX(mid_blk.end, end);
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if ((mid_blk.start == start) &&
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(mid_blk.end == end))
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identical = 1;
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}
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if (SEQ_LT(head_blk.start, head_blk.end)) {
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/* store overlapping range */
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saved_blks[0].start = SEQ_MAX(rcv_start, head_blk.start);
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saved_blks[0].end = SEQ_MIN(rcv_end, head_blk.end);
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}
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n = 1;
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/*
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* Second, if not ACKed, store the SACK block that
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* overlaps with the DSACK block unless it is identical
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*/
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if ((SEQ_LT(tp->rcv_nxt, mid_blk.end) &&
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!((mid_blk.start == saved_blks[0].start) &&
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(mid_blk.end == saved_blks[0].end))) ||
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identical == 1) {
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saved_blks[n].start = mid_blk.start;
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saved_blks[n++].end = mid_blk.end;
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}
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for (j = 0; (j < tp->rcv_numsacks) && (n < MAX_SACK_BLKS); j++) {
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if (((SEQ_LT(tp->sackblks[j].end, mid_blk.start) ||
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SEQ_GT(tp->sackblks[j].start, mid_blk.end)) &&
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(SEQ_GT(tp->sackblks[j].start, tp->rcv_nxt))))
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saved_blks[n++] = tp->sackblks[j];
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}
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j = 0;
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for (i = 0; i < n; i++) {
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/* we can end up with a stale initial entry */
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if (SEQ_LT(saved_blks[i].start, saved_blks[i].end)) {
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tp->sackblks[j++] = saved_blks[i];
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}
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}
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tp->rcv_numsacks = j;
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}
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/*
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* This function is called upon receipt of new valid data (while not in
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* header prediction mode), and it updates the ordered list of sacks.
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*/
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void
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tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
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{
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/*
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* First reported block MUST be the most recent one. Subsequent
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* blocks SHOULD be in the order in which they arrived at the
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* receiver. These two conditions make the implementation fully
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* compliant with RFC 2018.
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*/
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struct sackblk head_blk, saved_blks[MAX_SACK_BLKS];
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int num_head, num_saved, i;
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INP_WLOCK_ASSERT(tptoinpcb(tp));
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/* Check arguments. */
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KASSERT(SEQ_LEQ(rcv_start, rcv_end), ("rcv_start <= rcv_end"));
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if ((rcv_start == rcv_end) &&
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(tp->rcv_numsacks >= 1) &&
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(rcv_end == tp->sackblks[0].end)) {
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/* retaining DSACK block below rcv_nxt (todrop) */
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head_blk = tp->sackblks[0];
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} else {
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/* SACK block for the received segment. */
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head_blk.start = rcv_start;
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head_blk.end = rcv_end;
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}
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/*
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* Merge updated SACK blocks into head_blk, and save unchanged SACK
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* blocks into saved_blks[]. num_saved will have the number of the
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* saved SACK blocks.
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*/
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num_saved = 0;
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for (i = 0; i < tp->rcv_numsacks; i++) {
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tcp_seq start = tp->sackblks[i].start;
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tcp_seq end = tp->sackblks[i].end;
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if (SEQ_GEQ(start, end) || SEQ_LEQ(start, tp->rcv_nxt)) {
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/*
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* Discard this SACK block.
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*/
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} else if (SEQ_LEQ(head_blk.start, end) &&
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SEQ_GEQ(head_blk.end, start)) {
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/*
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* Merge this SACK block into head_blk. This SACK
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* block itself will be discarded.
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*/
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/*
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* |-|
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* |---| merge
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*
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* |-|
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* |---| merge
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*
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* |-----|
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* |-| DSACK smaller
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*
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* |-|
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* |-----| DSACK smaller
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*/
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if (head_blk.start == end)
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head_blk.start = start;
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else if (head_blk.end == start)
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head_blk.end = end;
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else {
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if (SEQ_LT(head_blk.start, start)) {
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tcp_seq temp = start;
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start = head_blk.start;
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head_blk.start = temp;
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}
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if (SEQ_GT(head_blk.end, end)) {
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tcp_seq temp = end;
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end = head_blk.end;
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head_blk.end = temp;
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}
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if ((head_blk.start != start) ||
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(head_blk.end != end)) {
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if ((num_saved >= 1) &&
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SEQ_GEQ(saved_blks[num_saved-1].start, start) &&
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SEQ_LEQ(saved_blks[num_saved-1].end, end))
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num_saved--;
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saved_blks[num_saved].start = start;
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saved_blks[num_saved].end = end;
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num_saved++;
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}
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}
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} else {
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/*
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* This block supercedes the prior block
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*/
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if ((num_saved >= 1) &&
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SEQ_GEQ(saved_blks[num_saved-1].start, start) &&
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SEQ_LEQ(saved_blks[num_saved-1].end, end))
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num_saved--;
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/*
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* Save this SACK block.
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*/
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saved_blks[num_saved].start = start;
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saved_blks[num_saved].end = end;
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num_saved++;
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}
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}
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/*
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* Update SACK list in tp->sackblks[].
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*/
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num_head = 0;
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if (SEQ_LT(rcv_start, rcv_end)) {
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/*
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* The received data segment is an out-of-order segment. Put
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* head_blk at the top of SACK list.
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*/
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tp->sackblks[0] = head_blk;
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num_head = 1;
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/*
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* If the number of saved SACK blocks exceeds its limit,
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* discard the last SACK block.
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*/
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if (num_saved >= MAX_SACK_BLKS)
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num_saved--;
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}
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if ((rcv_start == rcv_end) &&
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(rcv_start == tp->sackblks[0].end)) {
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num_head = 1;
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}
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if (num_saved > 0) {
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/*
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* Copy the saved SACK blocks back.
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*/
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bcopy(saved_blks, &tp->sackblks[num_head],
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sizeof(struct sackblk) * num_saved);
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}
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/* Save the number of SACK blocks. */
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tp->rcv_numsacks = num_head + num_saved;
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}
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void
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tcp_clean_dsack_blocks(struct tcpcb *tp)
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{
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struct sackblk saved_blks[MAX_SACK_BLKS];
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int num_saved, i;
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INP_WLOCK_ASSERT(tptoinpcb(tp));
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/*
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* Clean up any DSACK blocks that
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* are in our queue of sack blocks.
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*
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*/
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num_saved = 0;
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for (i = 0; i < tp->rcv_numsacks; i++) {
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tcp_seq start = tp->sackblks[i].start;
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tcp_seq end = tp->sackblks[i].end;
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if (SEQ_GEQ(start, end) || SEQ_LEQ(start, tp->rcv_nxt)) {
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/*
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* Discard this D-SACK block.
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*/
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continue;
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}
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/*
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* Save this SACK block.
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*/
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saved_blks[num_saved].start = start;
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saved_blks[num_saved].end = end;
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num_saved++;
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}
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if (num_saved > 0) {
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/*
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* Copy the saved SACK blocks back.
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*/
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bcopy(saved_blks, &tp->sackblks[0],
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sizeof(struct sackblk) * num_saved);
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}
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tp->rcv_numsacks = num_saved;
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}
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/*
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* Delete all receiver-side SACK information.
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*/
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void
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tcp_clean_sackreport(struct tcpcb *tp)
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{
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int i;
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INP_WLOCK_ASSERT(tptoinpcb(tp));
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tp->rcv_numsacks = 0;
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for (i = 0; i < MAX_SACK_BLKS; i++)
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tp->sackblks[i].start = tp->sackblks[i].end=0;
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}
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/*
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* Allocate struct sackhole.
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*/
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static struct sackhole *
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tcp_sackhole_alloc(struct tcpcb *tp, tcp_seq start, tcp_seq end)
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{
|
|
struct sackhole *hole;
|
|
|
|
if (tp->snd_numholes >= V_tcp_sack_maxholes ||
|
|
V_tcp_sack_globalholes >= V_tcp_sack_globalmaxholes) {
|
|
TCPSTAT_INC(tcps_sack_sboverflow);
|
|
return NULL;
|
|
}
|
|
|
|
hole = (struct sackhole *)uma_zalloc(V_sack_hole_zone, M_NOWAIT);
|
|
if (hole == NULL)
|
|
return NULL;
|
|
|
|
hole->start = start;
|
|
hole->end = end;
|
|
hole->rxmit = start;
|
|
|
|
tp->snd_numholes++;
|
|
atomic_add_int(&V_tcp_sack_globalholes, 1);
|
|
|
|
return hole;
|
|
}
|
|
|
|
/*
|
|
* Free struct sackhole.
|
|
*/
|
|
static void
|
|
tcp_sackhole_free(struct tcpcb *tp, struct sackhole *hole)
|
|
{
|
|
|
|
uma_zfree(V_sack_hole_zone, hole);
|
|
|
|
tp->snd_numholes--;
|
|
atomic_subtract_int(&V_tcp_sack_globalholes, 1);
|
|
|
|
KASSERT(tp->snd_numholes >= 0, ("tp->snd_numholes >= 0"));
|
|
KASSERT(V_tcp_sack_globalholes >= 0, ("tcp_sack_globalholes >= 0"));
|
|
}
|
|
|
|
/*
|
|
* Insert new SACK hole into scoreboard.
|
|
*/
|
|
static struct sackhole *
|
|
tcp_sackhole_insert(struct tcpcb *tp, tcp_seq start, tcp_seq end,
|
|
struct sackhole *after)
|
|
{
|
|
struct sackhole *hole;
|
|
|
|
/* Allocate a new SACK hole. */
|
|
hole = tcp_sackhole_alloc(tp, start, end);
|
|
if (hole == NULL)
|
|
return NULL;
|
|
|
|
/* Insert the new SACK hole into scoreboard. */
|
|
if (after != NULL)
|
|
TAILQ_INSERT_AFTER(&tp->snd_holes, after, hole, scblink);
|
|
else
|
|
TAILQ_INSERT_TAIL(&tp->snd_holes, hole, scblink);
|
|
|
|
/* Update SACK hint. */
|
|
if (tp->sackhint.nexthole == NULL)
|
|
tp->sackhint.nexthole = hole;
|
|
|
|
return hole;
|
|
}
|
|
|
|
/*
|
|
* Remove SACK hole from scoreboard.
|
|
*/
|
|
static void
|
|
tcp_sackhole_remove(struct tcpcb *tp, struct sackhole *hole)
|
|
{
|
|
|
|
/* Update SACK hint. */
|
|
if (tp->sackhint.nexthole == hole)
|
|
tp->sackhint.nexthole = TAILQ_NEXT(hole, scblink);
|
|
|
|
/* Remove this SACK hole. */
|
|
TAILQ_REMOVE(&tp->snd_holes, hole, scblink);
|
|
|
|
/* Free this SACK hole. */
|
|
tcp_sackhole_free(tp, hole);
|
|
}
|
|
|
|
/*
|
|
* Process cumulative ACK and the TCP SACK option to update the scoreboard.
|
|
* tp->snd_holes is an ordered list of holes (oldest to newest, in terms of
|
|
* the sequence space).
|
|
* Returns 1 if incoming ACK has previously unknown SACK information,
|
|
* 0 otherwise.
|
|
*/
|
|
int
|
|
tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack)
|
|
{
|
|
struct sackhole *cur, *temp;
|
|
struct sackblk sack, sack_blocks[TCP_MAX_SACK + 1], *sblkp;
|
|
int i, j, num_sack_blks, sack_changed;
|
|
int delivered_data, left_edge_delta;
|
|
|
|
INP_WLOCK_ASSERT(tptoinpcb(tp));
|
|
|
|
num_sack_blks = 0;
|
|
sack_changed = 0;
|
|
delivered_data = 0;
|
|
left_edge_delta = 0;
|
|
/*
|
|
* If SND.UNA will be advanced by SEG.ACK, and if SACK holes exist,
|
|
* treat [SND.UNA, SEG.ACK) as if it is a SACK block.
|
|
* Account changes to SND.UNA always in delivered data.
|
|
*/
|
|
if (SEQ_LT(tp->snd_una, th_ack) && !TAILQ_EMPTY(&tp->snd_holes)) {
|
|
left_edge_delta = th_ack - tp->snd_una;
|
|
sack_blocks[num_sack_blks].start = tp->snd_una;
|
|
sack_blocks[num_sack_blks++].end = th_ack;
|
|
/*
|
|
* Pulling snd_fack forward if we got here
|
|
* due to DSACK blocks
|
|
*/
|
|
if (SEQ_LT(tp->snd_fack, th_ack)) {
|
|
delivered_data += th_ack - tp->snd_una;
|
|
tp->snd_fack = th_ack;
|
|
sack_changed = 1;
|
|
}
|
|
}
|
|
/*
|
|
* Append received valid SACK blocks to sack_blocks[], but only if we
|
|
* received new blocks from the other side.
|
|
*/
|
|
if (to->to_flags & TOF_SACK) {
|
|
for (i = 0; i < to->to_nsacks; i++) {
|
|
bcopy((to->to_sacks + i * TCPOLEN_SACK),
|
|
&sack, sizeof(sack));
|
|
sack.start = ntohl(sack.start);
|
|
sack.end = ntohl(sack.end);
|
|
if (SEQ_GT(sack.end, sack.start) &&
|
|
SEQ_GT(sack.start, tp->snd_una) &&
|
|
SEQ_GT(sack.start, th_ack) &&
|
|
SEQ_LT(sack.start, tp->snd_max) &&
|
|
SEQ_GT(sack.end, tp->snd_una) &&
|
|
SEQ_LEQ(sack.end, tp->snd_max)) {
|
|
sack_blocks[num_sack_blks++] = sack;
|
|
} else if (SEQ_LEQ(sack.start, th_ack) &&
|
|
SEQ_LEQ(sack.end, th_ack)) {
|
|
/*
|
|
* Its a D-SACK block.
|
|
*/
|
|
tcp_record_dsack(tp, sack.start, sack.end, 0);
|
|
}
|
|
}
|
|
}
|
|
/*
|
|
* Return if SND.UNA is not advanced and no valid SACK block is
|
|
* received.
|
|
*/
|
|
if (num_sack_blks == 0)
|
|
return (sack_changed);
|
|
|
|
/*
|
|
* Sort the SACK blocks so we can update the scoreboard with just one
|
|
* pass. The overhead of sorting up to 4+1 elements is less than
|
|
* making up to 4+1 passes over the scoreboard.
|
|
*/
|
|
for (i = 0; i < num_sack_blks; i++) {
|
|
for (j = i + 1; j < num_sack_blks; j++) {
|
|
if (SEQ_GT(sack_blocks[i].end, sack_blocks[j].end)) {
|
|
sack = sack_blocks[i];
|
|
sack_blocks[i] = sack_blocks[j];
|
|
sack_blocks[j] = sack;
|
|
}
|
|
}
|
|
}
|
|
if (TAILQ_EMPTY(&tp->snd_holes)) {
|
|
/*
|
|
* Empty scoreboard. Need to initialize snd_fack (it may be
|
|
* uninitialized or have a bogus value). Scoreboard holes
|
|
* (from the sack blocks received) are created later below
|
|
* (in the logic that adds holes to the tail of the
|
|
* scoreboard).
|
|
*/
|
|
tp->snd_fack = SEQ_MAX(tp->snd_una, th_ack);
|
|
tp->sackhint.sacked_bytes = 0; /* reset */
|
|
}
|
|
/*
|
|
* In the while-loop below, incoming SACK blocks (sack_blocks[]) and
|
|
* SACK holes (snd_holes) are traversed from their tails with just
|
|
* one pass in order to reduce the number of compares especially when
|
|
* the bandwidth-delay product is large.
|
|
*
|
|
* Note: Typically, in the first RTT of SACK recovery, the highest
|
|
* three or four SACK blocks with the same ack number are received.
|
|
* In the second RTT, if retransmitted data segments are not lost,
|
|
* the highest three or four SACK blocks with ack number advancing
|
|
* are received.
|
|
*/
|
|
sblkp = &sack_blocks[num_sack_blks - 1]; /* Last SACK block */
|
|
tp->sackhint.last_sack_ack = sblkp->end;
|
|
if (SEQ_LT(tp->snd_fack, sblkp->start)) {
|
|
/*
|
|
* The highest SACK block is beyond fack. First,
|
|
* check if there was a successful Rescue Retransmission,
|
|
* and move this hole left. With normal holes, snd_fack
|
|
* is always to the right of the end.
|
|
*/
|
|
if (((temp = TAILQ_LAST(&tp->snd_holes, sackhole_head)) != NULL) &&
|
|
SEQ_LEQ(tp->snd_fack,temp->end)) {
|
|
temp->start = SEQ_MAX(tp->snd_fack, SEQ_MAX(tp->snd_una, th_ack));
|
|
temp->end = sblkp->start;
|
|
temp->rxmit = temp->start;
|
|
delivered_data += sblkp->end - sblkp->start;
|
|
tp->snd_fack = sblkp->end;
|
|
sblkp--;
|
|
sack_changed = 1;
|
|
} else {
|
|
/*
|
|
* Append a new SACK hole at the tail. If the
|
|
* second or later highest SACK blocks are also
|
|
* beyond the current fack, they will be inserted
|
|
* by way of hole splitting in the while-loop below.
|
|
*/
|
|
temp = tcp_sackhole_insert(tp, tp->snd_fack,sblkp->start,NULL);
|
|
if (temp != NULL) {
|
|
delivered_data += sblkp->end - sblkp->start;
|
|
tp->snd_fack = sblkp->end;
|
|
/* Go to the previous sack block. */
|
|
sblkp--;
|
|
sack_changed = 1;
|
|
} else {
|
|
/*
|
|
* We failed to add a new hole based on the current
|
|
* sack block. Skip over all the sack blocks that
|
|
* fall completely to the right of snd_fack and
|
|
* proceed to trim the scoreboard based on the
|
|
* remaining sack blocks. This also trims the
|
|
* scoreboard for th_ack (which is sack_blocks[0]).
|
|
*/
|
|
while (sblkp >= sack_blocks &&
|
|
SEQ_LT(tp->snd_fack, sblkp->start))
|
|
sblkp--;
|
|
if (sblkp >= sack_blocks &&
|
|
SEQ_LT(tp->snd_fack, sblkp->end)) {
|
|
delivered_data += sblkp->end - tp->snd_fack;
|
|
tp->snd_fack = sblkp->end;
|
|
sack_changed = 1;
|
|
}
|
|
}
|
|
}
|
|
} else if (SEQ_LT(tp->snd_fack, sblkp->end)) {
|
|
/* fack is advanced. */
|
|
delivered_data += sblkp->end - tp->snd_fack;
|
|
tp->snd_fack = sblkp->end;
|
|
sack_changed = 1;
|
|
}
|
|
cur = TAILQ_LAST(&tp->snd_holes, sackhole_head); /* Last SACK hole. */
|
|
/*
|
|
* Since the incoming sack blocks are sorted, we can process them
|
|
* making one sweep of the scoreboard.
|
|
*/
|
|
while (sblkp >= sack_blocks && cur != NULL) {
|
|
if (SEQ_GEQ(sblkp->start, cur->end)) {
|
|
/*
|
|
* SACKs data beyond the current hole. Go to the
|
|
* previous sack block.
|
|
*/
|
|
sblkp--;
|
|
continue;
|
|
}
|
|
if (SEQ_LEQ(sblkp->end, cur->start)) {
|
|
/*
|
|
* SACKs data before the current hole. Go to the
|
|
* previous hole.
|
|
*/
|
|
cur = TAILQ_PREV(cur, sackhole_head, scblink);
|
|
continue;
|
|
}
|
|
tp->sackhint.sack_bytes_rexmit -=
|
|
(SEQ_MIN(cur->rxmit, cur->end) - cur->start);
|
|
KASSERT(tp->sackhint.sack_bytes_rexmit >= 0,
|
|
("sackhint bytes rtx >= 0"));
|
|
sack_changed = 1;
|
|
if (SEQ_LEQ(sblkp->start, cur->start)) {
|
|
/* Data acks at least the beginning of hole. */
|
|
if (SEQ_GEQ(sblkp->end, cur->end)) {
|
|
/* Acks entire hole, so delete hole. */
|
|
delivered_data += (cur->end - cur->start);
|
|
temp = cur;
|
|
cur = TAILQ_PREV(cur, sackhole_head, scblink);
|
|
tcp_sackhole_remove(tp, temp);
|
|
/*
|
|
* The sack block may ack all or part of the
|
|
* next hole too, so continue onto the next
|
|
* hole.
|
|
*/
|
|
continue;
|
|
} else {
|
|
/* Move start of hole forward. */
|
|
delivered_data += (sblkp->end - cur->start);
|
|
cur->start = sblkp->end;
|
|
cur->rxmit = SEQ_MAX(cur->rxmit, cur->start);
|
|
}
|
|
} else {
|
|
/* Data acks at least the end of hole. */
|
|
if (SEQ_GEQ(sblkp->end, cur->end)) {
|
|
/* Move end of hole backward. */
|
|
delivered_data += (cur->end - sblkp->start);
|
|
cur->end = sblkp->start;
|
|
cur->rxmit = SEQ_MIN(cur->rxmit, cur->end);
|
|
if ((tp->t_flags & TF_LRD) && SEQ_GEQ(cur->rxmit, cur->end))
|
|
cur->rxmit = tp->snd_recover;
|
|
} else {
|
|
/*
|
|
* ACKs some data in middle of a hole; need
|
|
* to split current hole
|
|
*/
|
|
temp = tcp_sackhole_insert(tp, sblkp->end,
|
|
cur->end, cur);
|
|
if (temp != NULL) {
|
|
if (SEQ_GT(cur->rxmit, temp->rxmit)) {
|
|
temp->rxmit = cur->rxmit;
|
|
tp->sackhint.sack_bytes_rexmit +=
|
|
(SEQ_MIN(temp->rxmit,
|
|
temp->end) - temp->start);
|
|
}
|
|
cur->end = sblkp->start;
|
|
cur->rxmit = SEQ_MIN(cur->rxmit,
|
|
cur->end);
|
|
if ((tp->t_flags & TF_LRD) && SEQ_GEQ(cur->rxmit, cur->end))
|
|
cur->rxmit = tp->snd_recover;
|
|
delivered_data += (sblkp->end - sblkp->start);
|
|
}
|
|
}
|
|
}
|
|
tp->sackhint.sack_bytes_rexmit +=
|
|
(SEQ_MIN(cur->rxmit, cur->end) - cur->start);
|
|
/*
|
|
* Testing sblkp->start against cur->start tells us whether
|
|
* we're done with the sack block or the sack hole.
|
|
* Accordingly, we advance one or the other.
|
|
*/
|
|
if (SEQ_LEQ(sblkp->start, cur->start))
|
|
cur = TAILQ_PREV(cur, sackhole_head, scblink);
|
|
else
|
|
sblkp--;
|
|
}
|
|
if (!(to->to_flags & TOF_SACK))
|
|
/*
|
|
* If this ACK did not contain any
|
|
* SACK blocks, any only moved the
|
|
* left edge right, it is a pure
|
|
* cumulative ACK. Do not count
|
|
* DupAck for this. Also required
|
|
* for RFC6675 rescue retransmission.
|
|
*/
|
|
sack_changed = 0;
|
|
tp->sackhint.delivered_data = delivered_data;
|
|
tp->sackhint.sacked_bytes += delivered_data - left_edge_delta;
|
|
KASSERT((delivered_data >= 0), ("delivered_data < 0"));
|
|
KASSERT((tp->sackhint.sacked_bytes >= 0), ("sacked_bytes < 0"));
|
|
return (sack_changed);
|
|
}
|
|
|
|
/*
|
|
* Free all SACK holes to clear the scoreboard.
|
|
*/
|
|
void
|
|
tcp_free_sackholes(struct tcpcb *tp)
|
|
{
|
|
struct sackhole *q;
|
|
|
|
INP_WLOCK_ASSERT(tptoinpcb(tp));
|
|
while ((q = TAILQ_FIRST(&tp->snd_holes)) != NULL)
|
|
tcp_sackhole_remove(tp, q);
|
|
tp->sackhint.sack_bytes_rexmit = 0;
|
|
|
|
KASSERT(tp->snd_numholes == 0, ("tp->snd_numholes == 0"));
|
|
KASSERT(tp->sackhint.nexthole == NULL,
|
|
("tp->sackhint.nexthole == NULL"));
|
|
}
|
|
|
|
/*
|
|
* Partial ack handling within a sack recovery episode. Keeping this very
|
|
* simple for now. When a partial ack is received, force snd_cwnd to a value
|
|
* that will allow the sender to transmit no more than 2 segments. If
|
|
* necessary, a better scheme can be adopted at a later point, but for now,
|
|
* the goal is to prevent the sender from bursting a large amount of data in
|
|
* the midst of sack recovery.
|
|
*/
|
|
void
|
|
tcp_sack_partialack(struct tcpcb *tp, struct tcphdr *th)
|
|
{
|
|
int num_segs = 1;
|
|
u_int maxseg = tcp_maxseg(tp);
|
|
|
|
INP_WLOCK_ASSERT(tptoinpcb(tp));
|
|
tcp_timer_activate(tp, TT_REXMT, 0);
|
|
tp->t_rtttime = 0;
|
|
/* Send one or 2 segments based on how much new data was acked. */
|
|
if ((BYTES_THIS_ACK(tp, th) / maxseg) >= 2)
|
|
num_segs = 2;
|
|
tp->snd_cwnd = (tp->sackhint.sack_bytes_rexmit +
|
|
(tp->snd_nxt - tp->snd_recover) + num_segs * maxseg);
|
|
if (tp->snd_cwnd > tp->snd_ssthresh)
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
tp->t_flags |= TF_ACKNOW;
|
|
/*
|
|
* RFC6675 rescue retransmission
|
|
* Add a hole between th_ack (snd_una is not yet set) and snd_max,
|
|
* if this was a pure cumulative ACK and no data was send beyond
|
|
* recovery point. Since the data in the socket has not been freed
|
|
* at this point, we check if the scoreboard is empty, and the ACK
|
|
* delivered some new data, indicating a full ACK. Also, if the
|
|
* recovery point is still at snd_max, we are probably application
|
|
* limited. However, this inference might not always be true. The
|
|
* rescue retransmission may rarely be slightly premature
|
|
* compared to RFC6675.
|
|
* The corresponding ACK+SACK will cause any further outstanding
|
|
* segments to be retransmitted. This addresses a corner case, when
|
|
* the trailing packets of a window are lost and no further data
|
|
* is available for sending.
|
|
*/
|
|
if ((V_tcp_do_newsack) &&
|
|
SEQ_LT(th->th_ack, tp->snd_recover) &&
|
|
(tp->snd_recover == tp->snd_max) &&
|
|
TAILQ_EMPTY(&tp->snd_holes) &&
|
|
(tp->sackhint.delivered_data > 0)) {
|
|
/*
|
|
* Exclude FIN sequence space in
|
|
* the hole for the rescue retransmission,
|
|
* and also don't create a hole, if only
|
|
* the ACK for a FIN is outstanding.
|
|
*/
|
|
tcp_seq highdata = tp->snd_max;
|
|
if (tp->t_flags & TF_SENTFIN)
|
|
highdata--;
|
|
if (th->th_ack != highdata) {
|
|
tp->snd_fack = th->th_ack;
|
|
(void)tcp_sackhole_insert(tp, SEQ_MAX(th->th_ack,
|
|
highdata - maxseg), highdata, NULL);
|
|
}
|
|
}
|
|
(void) tcp_output(tp);
|
|
}
|
|
|
|
#if 0
|
|
/*
|
|
* Debug version of tcp_sack_output() that walks the scoreboard. Used for
|
|
* now to sanity check the hint.
|
|
*/
|
|
static struct sackhole *
|
|
tcp_sack_output_debug(struct tcpcb *tp, int *sack_bytes_rexmt)
|
|
{
|
|
struct sackhole *p;
|
|
|
|
INP_WLOCK_ASSERT(tptoinpcb(tp));
|
|
*sack_bytes_rexmt = 0;
|
|
TAILQ_FOREACH(p, &tp->snd_holes, scblink) {
|
|
if (SEQ_LT(p->rxmit, p->end)) {
|
|
if (SEQ_LT(p->rxmit, tp->snd_una)) {/* old SACK hole */
|
|
continue;
|
|
}
|
|
*sack_bytes_rexmt += (p->rxmit - p->start);
|
|
break;
|
|
}
|
|
*sack_bytes_rexmt += (SEQ_MIN(p->rxmit, p->end) - p->start);
|
|
}
|
|
return (p);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Returns the next hole to retransmit and the number of retransmitted bytes
|
|
* from the scoreboard. We store both the next hole and the number of
|
|
* retransmitted bytes as hints (and recompute these on the fly upon SACK/ACK
|
|
* reception). This avoids scoreboard traversals completely.
|
|
*
|
|
* The loop here will traverse *at most* one link. Here's the argument. For
|
|
* the loop to traverse more than 1 link before finding the next hole to
|
|
* retransmit, we would need to have at least 1 node following the current
|
|
* hint with (rxmit == end). But, for all holes following the current hint,
|
|
* (start == rxmit), since we have not yet retransmitted from them.
|
|
* Therefore, in order to traverse more 1 link in the loop below, we need to
|
|
* have at least one node following the current hint with (start == rxmit ==
|
|
* end). But that can't happen, (start == end) means that all the data in
|
|
* that hole has been sacked, in which case, the hole would have been removed
|
|
* from the scoreboard.
|
|
*/
|
|
struct sackhole *
|
|
tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt)
|
|
{
|
|
struct sackhole *hole = NULL;
|
|
|
|
INP_WLOCK_ASSERT(tptoinpcb(tp));
|
|
*sack_bytes_rexmt = tp->sackhint.sack_bytes_rexmit;
|
|
hole = tp->sackhint.nexthole;
|
|
if (hole == NULL)
|
|
return (hole);
|
|
if (SEQ_GEQ(hole->rxmit, hole->end)) {
|
|
for (;;) {
|
|
hole = TAILQ_NEXT(hole, scblink);
|
|
if (hole == NULL)
|
|
return (hole);
|
|
if (SEQ_LT(hole->rxmit, hole->end)) {
|
|
tp->sackhint.nexthole = hole;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
KASSERT(SEQ_LT(hole->start, hole->end), ("%s: hole.start >= hole.end", __func__));
|
|
if (!(V_tcp_do_newsack)) {
|
|
KASSERT(SEQ_LT(hole->start, tp->snd_fack), ("%s: hole.start >= snd.fack", __func__));
|
|
KASSERT(SEQ_LT(hole->end, tp->snd_fack), ("%s: hole.end >= snd.fack", __func__));
|
|
KASSERT(SEQ_LT(hole->rxmit, tp->snd_fack), ("%s: hole.rxmit >= snd.fack", __func__));
|
|
if (SEQ_GEQ(hole->start, hole->end) ||
|
|
SEQ_GEQ(hole->start, tp->snd_fack) ||
|
|
SEQ_GEQ(hole->end, tp->snd_fack) ||
|
|
SEQ_GEQ(hole->rxmit, tp->snd_fack)) {
|
|
log(LOG_CRIT,"tcp: invalid SACK hole (%u-%u,%u) vs fwd ack %u, ignoring.\n",
|
|
hole->start, hole->end, hole->rxmit, tp->snd_fack);
|
|
return (NULL);
|
|
}
|
|
}
|
|
return (hole);
|
|
}
|
|
|
|
/*
|
|
* After a timeout, the SACK list may be rebuilt. This SACK information
|
|
* should be used to avoid retransmitting SACKed data. This function
|
|
* traverses the SACK list to see if snd_nxt should be moved forward.
|
|
*/
|
|
void
|
|
tcp_sack_adjust(struct tcpcb *tp)
|
|
{
|
|
struct sackhole *p, *cur = TAILQ_FIRST(&tp->snd_holes);
|
|
|
|
INP_WLOCK_ASSERT(tptoinpcb(tp));
|
|
if (cur == NULL)
|
|
return; /* No holes */
|
|
if (SEQ_GEQ(tp->snd_nxt, tp->snd_fack))
|
|
return; /* We're already beyond any SACKed blocks */
|
|
/*-
|
|
* Two cases for which we want to advance snd_nxt:
|
|
* i) snd_nxt lies between end of one hole and beginning of another
|
|
* ii) snd_nxt lies between end of last hole and snd_fack
|
|
*/
|
|
while ((p = TAILQ_NEXT(cur, scblink)) != NULL) {
|
|
if (SEQ_LT(tp->snd_nxt, cur->end))
|
|
return;
|
|
if (SEQ_GEQ(tp->snd_nxt, p->start))
|
|
cur = p;
|
|
else {
|
|
tp->snd_nxt = p->start;
|
|
return;
|
|
}
|
|
}
|
|
if (SEQ_LT(tp->snd_nxt, cur->end))
|
|
return;
|
|
tp->snd_nxt = tp->snd_fack;
|
|
}
|
|
|
|
/*
|
|
* Lost Retransmission Detection
|
|
* Check is FACK is beyond the rexmit of the leftmost hole.
|
|
* If yes, we restart sending from still existing holes,
|
|
* and adjust cwnd via the congestion control module.
|
|
*/
|
|
void
|
|
tcp_sack_lost_retransmission(struct tcpcb *tp, struct tcphdr *th)
|
|
{
|
|
struct sackhole *temp;
|
|
|
|
if (IN_RECOVERY(tp->t_flags) &&
|
|
SEQ_GT(tp->snd_fack, tp->snd_recover) &&
|
|
((temp = TAILQ_FIRST(&tp->snd_holes)) != NULL) &&
|
|
SEQ_GEQ(temp->rxmit, temp->end) &&
|
|
SEQ_GEQ(tp->snd_fack, temp->rxmit)) {
|
|
TCPSTAT_INC(tcps_sack_lostrexmt);
|
|
/*
|
|
* Start retransmissions from the first hole, and
|
|
* subsequently all other remaining holes, including
|
|
* those, which had been sent completely before.
|
|
*/
|
|
tp->sackhint.nexthole = temp;
|
|
TAILQ_FOREACH(temp, &tp->snd_holes, scblink) {
|
|
if (SEQ_GEQ(tp->snd_fack, temp->rxmit) &&
|
|
SEQ_GEQ(temp->rxmit, temp->end))
|
|
temp->rxmit = temp->start;
|
|
}
|
|
/*
|
|
* Remember the old ssthresh, to deduct the beta factor used
|
|
* by the CC module. Finally, set cwnd to ssthresh just
|
|
* prior to invoking another cwnd reduction by the CC
|
|
* module, to not shrink it excessively.
|
|
*/
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
/*
|
|
* Formally exit recovery, and let the CC module adjust
|
|
* ssthresh as intended.
|
|
*/
|
|
EXIT_RECOVERY(tp->t_flags);
|
|
cc_cong_signal(tp, th, CC_NDUPACK);
|
|
/*
|
|
* For PRR, adjust recover_fs as if this new reduction
|
|
* initialized this variable.
|
|
* cwnd will be adjusted by SACK or PRR processing
|
|
* subsequently, only set it to a safe value here.
|
|
*/
|
|
tp->snd_cwnd = tcp_maxseg(tp);
|
|
tp->sackhint.recover_fs = (tp->snd_max - tp->snd_una) -
|
|
tp->sackhint.recover_fs;
|
|
}
|
|
}
|