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

   1 /*
   2  * Timestamp mechanism for udp tunnel
   3  *
   4  * arguments: <max-skew> <max-age>
   5  *
   6  * encoding: prepend 4 bytes of UNIX time in network byte order
   7  *
   8  * <max-age> is maximum age in seconds we will accept a packet (or 0
   9  * for any age); <max-skew> is maximum future age in seconds we will
  10  * accept a packet (or 0 for any future age).
  11  *
  12  */
  13 /*
  14  * Copyright (C) 2000 Ian Jackson
  15  *
  16  * This is free software; you can redistribute it and/or modify it
  17  * under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful, but
  22  * WITHOUT ANY WARRANTY; without even the implied warranty of
  23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  24  * General Public License for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License
  27  * along with userv-utils; if not, write to the Free Software
  28  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  29  */
  30
  31 #include <stdint.h>
  32 #include <netinet/in.h>
  33
  34 #include "forwarder.h"
  35
  36 #define WARN_EVERY 30
  37
  38 struct mechdata {
  39   time_t max_skew, max_age;
  40   time_t next_warn;
  41 };
  42
  43 static void mds_timestamp(struct mechdata **md_r) {
  44   struct mechdata *md;
  45
  46   md= xmalloc(sizeof(md));
  47
  48   md->max_skew= getarg_ulong();
  49   md->max_age= getarg_ulong();
  50   md->next_warn= now();
  51   *md_r= md;
  52 }
  53
  54 static void mes_timestamp(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  55   mds_timestamp(md_r);
  56   *maxprefix_io += 4;
  57 }
  58
  59 static void menc_timestamp(struct mechdata *md, struct buffer *buf) {
  60   *(uint32_t*)buf_prepend(buf,4)= htonl(now());
  61 }
  62
  63 static const char *mdec_timestamp(struct mechdata *md, struct buffer *buf) {
  64   static char cbuf[40];
  65
  66   uint32_t *tp, timestamp;
  67   time_t tnow;
  68   long age;
  69
  70   BUF_UNPREPEND(tp,buf,4);
  71   timestamp= ntohl(*tp);
  72
  73   tnow= now();
  74   age= timestamp - (uint32_t)tnow;
  75   if (age > 0) {
  76     if (!md->max_age || age <= md->max_age) return 0;
  77     sprintf(cbuf,"packet too old (%lds)",age);
  78   } else if (age < 0) {
  79     if (!md->max_skew || age >= -md->max_skew) return 0;
  80     sprintf(cbuf,"too much skew (%lds)",-age);
  81   }
  82
  83   if (tnow < md->next_warn) return "";
  84
  85   md->next_warn= tnow+WARN_EVERY;
  86   return cbuf;
  87 }
  88
  89 STANDARD_MECHANISMLIST("timestamp",timestamp);