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

   1 /*
   2  * Timestamp mechanism
   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 #include <stdint.h>
  15 #include <netinet/in.h>
  16
  17 #include "forwarder.h"
  18
  19 struct mechdata {
  20   uint32_t max_skew, max_age;
  21 };
  22
  23 static void mds_timestamp(struct mechdata **md_r) {
  24   struct mechdata *md;
  25
  26   md= xmalloc(sizeof(md));
  27
  28   md->max_skew= getarg_ulong();
  29   md->max_age= getarg_ulong();
  30   *md_r= md;
  31 }
  32
  33 static void mes_timestamp(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  34   mds_timestamp(md_r);
  35   *maxprefix_io += 4;
  36 }
  37
  38 static void menc_timestamp(struct mechdata *md, struct buffer *buf) {
  39   *(uint32_t*)buf_prepend(buf,4)= htonl(now());
  40 }
  41
  42 static const char *mdec_timestamp(struct mechdata *md, struct buffer *buf) {
  43   static char cbuf[40];
  44
  45   uint32_t *tp, timestamp, tnow;
  46   long age;
  47
  48   BUF_UNPREPEND(tp,buf,4);
  49   timestamp= ntohl(*tp);
  50
  51   tnow= now();
  52   age= timestamp - tnow;
  53   if (age > 0) {
  54     if (md->max_age && age > md->max_age) {
  55       sprintf(cbuf,"packet too old (%lds)",age);
  56       return cbuf;
  57     }
  58   } else if (age < 0) {
  59     if (md->max_skew && age > md->max_skew) {
  60       sprintf(cbuf,"too much skew (%lds)",-age);
  61       return cbuf;
  62     }
  63   }
  64
  65   return 0;
  66 }
  67
  68 STANDARD_MECHANISMLIST("timestamp",timestamp);