freebsd-skq/sys/netinet/tcp_seq.h
bz e7eef5c811 Fix PAWS (Protect Against Wrapped Sequence numbers) in cases when
hz >> 1000 and thus getting outside the timestamp clock frequenceny of
1ms < x < 1s per tick as mandated by RFC1323, leading to connection
resets on idle connections.

Always use a granularity of 1ms using getmicrouptime() making all but
relevant callouts independent of hz.

Use getmicrouptime(), not getmicrotime() as the latter may make a jump
possibly breaking TCP nfsroot mounts having our timestamps move forward
for more than 24.8 days in a second without having been idle for that
long.

PR:		kern/61404
Reviewed by:	jhb, mav, rrs
Discussed with:	silby, lstewart
Sponsored by:	Sandvine Incorporated (originally in 2011)
MFC after:	6 weeks
2012-02-15 16:09:56 +00:00

96 lines
3.3 KiB
C

/*-
* Copyright (c) 1982, 1986, 1993, 1995
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_seq.h 8.3 (Berkeley) 6/21/95
* $FreeBSD$
*/
#ifndef _NETINET_TCP_SEQ_H_
#define _NETINET_TCP_SEQ_H_
/*
* TCP sequence numbers are 32 bit integers operated
* on with modular arithmetic. These macros can be
* used to compare such integers.
*/
#define SEQ_LT(a,b) ((int)((a)-(b)) < 0)
#define SEQ_LEQ(a,b) ((int)((a)-(b)) <= 0)
#define SEQ_GT(a,b) ((int)((a)-(b)) > 0)
#define SEQ_GEQ(a,b) ((int)((a)-(b)) >= 0)
#define SEQ_MIN(a, b) ((SEQ_LT(a, b)) ? (a) : (b))
#define SEQ_MAX(a, b) ((SEQ_GT(a, b)) ? (a) : (b))
/* for modulo comparisons of timestamps */
#define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
#define TSTMP_GT(a,b) ((int)((a)-(b)) > 0)
#define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
/*
* Macros to initialize tcp sequence numbers for
* send and receive from initial send and receive
* sequence numbers.
*/
#define tcp_rcvseqinit(tp) \
(tp)->rcv_adv = (tp)->rcv_nxt = (tp)->irs + 1
#define tcp_sendseqinit(tp) \
(tp)->snd_una = (tp)->snd_nxt = (tp)->snd_max = (tp)->snd_up = \
(tp)->snd_recover = (tp)->iss
#ifdef _KERNEL
/*
* Clock macros for RFC 1323 timestamps.
*/
#define TCP_TS_TO_TICKS(_t) ((_t) * hz / 1000)
/* Timestamp wrap-around time, 24 days. */
#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * 1000)
/*
* tcp_ts_getticks() in ms, should be 1ms < x < 1000ms according to RFC 1323.
* We always use 1ms granularity independent of hz.
*/
static __inline u_int
tcp_ts_getticks(void)
{
struct timeval tv;
u_long ms;
/*
* getmicrouptime() should be good enough for any 1-1000ms granularity.
* Do not use getmicrotime() here as it might break nfsroot/tcp.
*/
getmicrouptime(&tv);
ms = tv.tv_sec * 1000 + tv.tv_usec / 1000;
return (ms);
}
#endif /* _KERNEL */
#endif /* _NETINET_TCP_SEQ_H_ */