[Xorp-hackers] Constructing packets

[Victor Faion]

On Wed, Feb 25, 2009 at 10:17, Pavlin Radoslavov
<pavlin at icsi.berkeley.edu> wrote:
> Victor Faion <vfaion at gmail.com> wrote:
>
>> Thank you for the help, the embed_*() and extract_*() functions are
>> working. I use embed_8() on each character of the string. I don't
>> understand when (or if) I need to use the alignment functions in
>> AlignData. When I receive the packet now I just use the extract_*()
>> functions and everything seems to be aligned.
>
> You don't need AlignData. That class is used only in the FEA when we
> need to deal with certain system struct types when they are aligned
> with data buffers.
>
>> A sort of related question, I was trying to put a timestamp in a
>> packet using TimeVal::sec(). To test the time functions I just did
>> this:
>>
>> TimeVal now;
>> TimerList::system_gettimeofday(&now);
>> XLOG_INFO("Time is %s", now.pretty_print().c_str());
>>
>> But when I run this I get something like this:
>>
>> Time is Thu Apr  6 08:23:07 1972
>>
>> even though the system clock is set right and date gives the right
>> time. Am I using these functions in the wrong way?
>
> You shouldn't use TimerList::system_gettimeofday() to print
> the current time.
> Depending on the OS, TimerList::system_gettimeofday() might call
> either clock_gettime(CLOCK_MONOTONIC) or gettimeofday(2)
> (the former is preferred).
> If it is the former, then you get the monotonic time since some
> unspecified starting point in the past.
>
> If you really want to print the current time then you can use
> xlog_localtime2string() function from libxorp (you must include
> header file "libxorp/xlog.h").
>
> Regards,
> Pavlin
>

Cheers, that works for me :-)

Victor