Wireshark · Wireshark-dev: Re: [Wireshark-dev] getting the time

[Guy Harris <guy@xxxxxxxxxxxx>]

On Jan 20, 2010, at 1:34 PM, Brian Oleksa wrote:

> I forgot to add the format of the time stamp that I am trying to get.
> 
> ms since the epoch (jan 1, 1970) as a 8 byte network byte order integer
> 
> Is there built in functions that can be used..??

Do you mean that you have a protocol that has an 8-byte network-byte-order integer whose value is a count of milliseconds since midnight, January 1, 1970?

The function to get the value would be tvb_get_ntoh64(), but that just gives you a guint64 count of milliseconds.

If you want to add that to the protocol tree as an FT_ABSOLUTE_TIME, that requires more work.

First - is that midnight, January 1, 1970, UTC, or midnight, January 1, 1970 *local* time?  If it's local time, that's a bit more work; I'll assume it's UTC here.

Values for FT_ABSOLUTE_TIME fields are nstime_t's; those are structures with a "secs" and "nsecs" field.  If you have a 64-bit milliseconds since the Epoch, and you want to convert it to an nstime_t for use with an FT_ABSOLUTE_TIME field, you'd do

	guint64 msecs_since_the_epoch;
	nstime_t t;

		...

	t.secs = msecs_since_the_epoch/1000;
	t.nsecs = (msecs_since_the_epoch%1000)*1000000;	/* milliseconds to nanoseconds */