mdw@git.distorted.org.uk Git - userv-utils/blob - ipif/mech-timestamp.c

   1 /*
   2  * Timestamp mechanism for udp tunnel
   3  *
   4  * mechanism: timestamp
   5  * arguments: <max-skew> <max-age>
   6  *
   7  * restrictions: none
   8  * encoding: prepend 4 bytes of UNIX time in network byte order
   9  *
  10  * <max-age> is maximum age in seconds we will accept a packet (or 0
  11  * for any age); <max-skew> is maximum future age in seconds we will
  12  * accept a packet (or 0 for any future age).
  13  *
  14  */
  15 /*
  16  * Copyright (C) 2000,2003 Ian Jackson
  17  * This file is part of ipif, part of userv-utils
  18  *
  19  * This is free software; you can redistribute it and/or modify it
  20  * under the terms of the GNU General Public License as published by
  21  * the Free Software Foundation; either version 2 of the License, or
  22  * (at your option) any later version.
  23  *
  24  * This program is distributed in the hope that it will be useful, but
  25  * WITHOUT ANY WARRANTY; without even the implied warranty of
  26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  27  * General Public License for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * along with userv-utils; if not, write to the Free Software
  31  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  32  */
  33
  34 #include <stdint.h>
  35 #include <netinet/in.h>
  36
  37 #include "forwarder.h"
  38
  39 #define WARN_EVERY 30
  40
  41 struct mechdata {
  42   time_t max_skew, max_age;
  43   time_t next_warn;
  44 };
  45
  46 static void mds_timestamp(struct mechdata **md_r) {
  47   struct mechdata *md;
  48
  49   md= xmalloc(sizeof(md));
  50
  51   md->max_skew= getarg_ulong();
  52   md->max_age= getarg_ulong();
  53   md->next_warn= now();
  54   *md_r= md;
  55 }
  56
  57 static void mes_timestamp(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  58   mds_timestamp(md_r);
  59   *maxprefix_io += 4;
  60 }
  61
  62 static void menc_timestamp(struct mechdata *md, struct buffer *buf) {
  63   *(uint32_t*)buf_prepend(buf,4)= htonl(now());
  64 }
  65
  66 static const char *mdec_timestamp(struct mechdata *md, struct buffer *buf) {
  67   static char cbuf[40];
  68
  69   uint32_t *tp, timestamp;
  70   time_t tnow;
  71   long age;
  72
  73   BUF_UNPREPEND(tp,buf,4);
  74   timestamp= ntohl(*tp);
  75
  76   tnow= now();
  77   age= timestamp - (uint32_t)tnow;
  78   if (age > 0) {
  79     if (!md->max_age || age <= md->max_age) return 0;
  80     sprintf(cbuf,"packet too old (%lds)",age);
  81   } else if (age < 0) {
  82     if (!md->max_skew || age >= -md->max_skew) return 0;
  83     sprintf(cbuf,"too much skew (%lds)",-age);
  84   } else {
  85     return 0;
  86   }
  87
  88   if (tnow < md->next_warn) return "";
  89
  90   md->next_warn= tnow+WARN_EVERY;
  91   return cbuf;
  92 }
  93
  94 STANDARD_MECHANISMLIST("timestamp",timestamp);