Wireshark · Wireshark-dev: Re: [Wireshark-dev] time question

[Brian Oleksa <oleksab@xxxxxxxxxxxxxxxxxxxxxx>]

Anders

Yes...I am aware of that. This is what I did...but I am still getting an 
invalid date. This is exactly what I get as the output (Jan 15th, 1970 
16:59:15 UTC)

                                   nstime_t t;
                                   guint32 msecs_since_the_epoch;
                                   struct tm *tmp;

                                   msecs_since_the_epoch = 
tvb_get_ntohl(tvb, offset);
                                   t.secs = msecs_since_the_epoch / 1000;
                                   t.nsecs = (msecs_since_the_epoch % 
1000)*1000000; /* milliseconds to nanoseconds */
                                   tmp = gmtime(&t.secs);

                               if (tmp != NULL)
                                   {
                                   
proto_tree_add_time_format(mgen_sub_tree, hf_helen_time, tvb, offset, 4, &t,
                                           "Date: %s %2d, %d 
%02d:%02d:%02d UTC", mon_names[tmp->tm_mon], tmp->tm_mday,
                                           tmp->tm_year + 1900, 
tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
                                   }
                               offset += 4;

Thanks,
Brian

Anders Broman wrote:
> Brian Oleksa skrev 2010-04-08 16:41:
>   
> > Wiresharkers
> >
> > I am trying to dissect the time in a particular packet. Here is it's format:
> >
> > "The time is the source computer's system time in Greenwich Mean Time
> > (GMT)." The size is 32 bits or 4 bytes.
> >
> > What is the best method to use to dissect this time..?? I tired
> > this...but did not have any luck:
> >
> >                          nstime_t t;
> >                          guint64 msecs_since_the_epoch;
> >                          struct tm *tmp;
> >                          msecs_since_the_epoch = tvb_get_ntoh64(tvb, offset);
> >    
> >     
> Well you are fetching 8 bytes not four...
>   
> >                          t.secs = msecs_since_the_epoch / 1000;
> >                          t.nsecs = (msecs_since_the_epoch %
> > 1000)*1000000; /* milliseconds to nanoseconds */
> >                          tmp = gmtime(&t.secs);
> >
> >                      if (tmp != NULL)
> >                          {
> >                          proto_tree_add_time_format(time_sub_tree,
> > hf_helen_time, tvb, offset, 4,&t,
> >                                  "Date: %s %2d, %d %02d:%02d:%02d UTC",
> > mon_names[tmp->tm_mon], tmp->tm_mday,
> >                                  tmp->tm_year + 1900, tmp->tm_hour,
> > tmp->tm_min, tmp->tm_sec);
> >                          }
> >                          offset += 4
> >
> >
> >
> >
> > Also...I am trying to dissect longitude, latitude and altitude. Here is
> > it's format. The size is also 32 bits or 4 bytes.
> >
> > The<latitude>,<longitude>, and<altitude>  fields contain values
> > corresponding to GPS information for the MGEN source if it was
> > available. The<latitude>  and<longitude>  fields are encoded as follows:
> >
> > <fieldValue>  = (unsigned long)((<actualValue>+180.0)*60000.0)
> >
> > The<altitude>  field is the direct representation of the altitude value
> > available from the source's GPS system.
> >
> > I tried this but had no luck:
> >
> >              longitude = tvb_get_ntoh64(tvb, offset);
> >    
> >     
> Well you are fetching 8 bytes not four...
>   
> >              longitude = (longitude+180)*60000;
> >    
> >     
> Assuming the field on the wire is encoded as:
>
> <fieldValue>  = (unsigned long)((<actualValue>+180.0)*60000.0)
>
> shouldn't that be (double)actualValue= (longitude/60000.0)-180
>   
> >              proto_tree_add_uint_format(mgen_sub_tree, hf_helen_length,
> > tvb, offset, 4, 0,
> >                    "Longitude: %f", longitude);
> >              offset += 4;
> >
> >
> >
> > Thanks,
> > Brian
> >
> >
> >
> >
> >
> >
> > ___________________________________________________________________________
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> >    
> >     
>
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