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

[wsgd <wsgd@xxxxxxx>]

The 4 bytes contains seconds (and not milli-seconds).


Olivier

Brian Oleksa a écrit :
> 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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> >   
> >     
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>   


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