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/*
* Timestamp mechanism for udp tunnel
*
* mechanism: timestamp
* arguments: <max-skew> <max-age>
*
* restrictions: none
* encoding: prepend 4 bytes of UNIX time in network byte order
*
* <max-age> is maximum age in seconds we will accept a packet (or 0
* for any age); <max-skew> is maximum future age in seconds we will
* accept a packet (or 0 for any future age).
*
*/
/*
* This file is part of ipif, part of userv-utils
*
* Copyright 1996-2013 Ian Jackson <ijackson@chiark.greenend.org.uk>
* Copyright 1998 David Damerell <damerell@chiark.greenend.org.uk>
* Copyright 1999,2003
* Chancellor Masters and Scholars of the University of Cambridge
* Copyright 2010 Tony Finch <fanf@dotat.at>
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with userv-utils; if not, see http://www.gnu.org/licenses/.
*/
#include <stdint.h>
#include <netinet/in.h>
#include "forwarder.h"
#define WARN_EVERY 30
struct mechdata {
time_t max_skew, max_age;
time_t next_warn;
};
static void mds_timestamp(struct mechdata **md_r) {
struct mechdata *md;
md= xmalloc(sizeof(md));
md->max_skew= getarg_ulong();
md->max_age= getarg_ulong();
md->next_warn= now();
*md_r= md;
}
static void mes_timestamp(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
mds_timestamp(md_r);
*maxprefix_io += 4;
}
static void menc_timestamp(struct mechdata *md, struct buffer *buf) {
*(uint32_t*)buf_prepend(buf,4)= htonl(now());
}
static const char *mdec_timestamp(struct mechdata *md, struct buffer *buf) {
static char cbuf[40];
uint32_t *tp, timestamp;
time_t tnow;
long age;
BUF_UNPREPEND(tp,buf,4);
timestamp= ntohl(*tp);
tnow= now();
age= timestamp - (uint32_t)tnow;
if (age > 0) {
if (!md->max_age || age <= md->max_age) return 0;
sprintf(cbuf,"packet too old (%lds)",age);
} else if (age < 0) {
if (!md->max_skew || age >= -md->max_skew) return 0;
sprintf(cbuf,"too much skew (%lds)",-age);
} else {
return 0;
}
if (tnow < md->next_warn) return "";
md->next_warn= tnow+WARN_EVERY;
return cbuf;
}
STANDARD_MECHANISMLIST("timestamp",timestamp);
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