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 Ian Jackson
  17  *
  18  * This is free software; you can redistribute it and/or modify it
  19  * under the terms of the GNU General Public License as published by
  20  * the Free Software Foundation; either version 2 of the License, or
  21  * (at your option) any later version.
  22  *
  23  * This program is distributed in the hope that it will be useful, but
  24  * WITHOUT ANY WARRANTY; without even the implied warranty of
  25  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  26  * General Public License for more details.
  27  *
  28  * You should have received a copy of the GNU General Public License
  29  * along with userv-utils; if not, write to the Free Software
  30  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  31  */
  32
  33 #include <stdint.h>
  34 #include <netinet/in.h>
  35
  36 #include "forwarder.h"
  37
  38 #define WARN_EVERY 30
  39
  40 struct mechdata {
  41   time_t max_skew, max_age;
  42   time_t next_warn;
  43 };
  44
  45 static void mds_timestamp(struct mechdata **md_r) {
  46   struct mechdata *md;
  47
  48   md= xmalloc(sizeof(md));
  49
  50   md->max_skew= getarg_ulong();
  51   md->max_age= getarg_ulong();
  52   md->next_warn= now();
  53   *md_r= md;
  54 }
  55
  56 static void mes_timestamp(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  57   mds_timestamp(md_r);
  58   *maxprefix_io += 4;
  59 }
  60
  61 static void menc_timestamp(struct mechdata *md, struct buffer *buf) {
  62   *(uint32_t*)buf_prepend(buf,4)= htonl(now());
  63 }
  64
  65 static const char *mdec_timestamp(struct mechdata *md, struct buffer *buf) {
  66   static char cbuf[40];
  67
  68   uint32_t *tp, timestamp;
  69   time_t tnow;
  70   long age;
  71
  72   BUF_UNPREPEND(tp,buf,4);
  73   timestamp= ntohl(*tp);
  74
  75   tnow= now();
  76   age= timestamp - (uint32_t)tnow;
  77   if (age > 0) {
  78     if (!md->max_age || age <= md->max_age) return 0;
  79     sprintf(cbuf,"packet too old (%lds)",age);
  80   } else if (age < 0) {
  81     if (!md->max_skew || age >= -md->max_skew) return 0;
  82     sprintf(cbuf,"too much skew (%lds)",-age);
  83   } else {
  84     return 0;
  85   }
  86
  87   if (tnow < md->next_warn) return "";
  88
  89   md->next_warn= tnow+WARN_EVERY;
  90   return cbuf;
  91 }
  92
  93 STANDARD_MECHANISMLIST("timestamp",timestamp);