Wireshark mailing list archives

Re: getting the time


From: Guy Harris <guy () alum mit edu>
Date: Wed, 20 Jan 2010 13:44:17 -0800


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 */
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