[SOLVED] sending MAC packets --- again, and again

Daniel Valencia fetrovsky at yahoo.com
Sat May 21 11:21:36 PDT 2005


Hello all

Thanks to your answers, and thanks to Charles Swiger
for mentioning the timeout value, i went to the
manpage and re-read that, and figured out that I had
misinterpreted the timeout purpose.  I thought that if
I set it to zero, I would wait forever and as soon as
a packet arrived I would be notified... I was wrong...
When I set it to zero, pcap_loop would actually wait
forever before notifying me of any received packets. 
Setting the timeout to 1 I get the packets immediately
after pcap sees them.

The only problem is, I'm imposing an artificial 1ms
delay in my receiving of packets.  It's not actually
important at this point, but it would be nice if it
weren't that way.

Again, thank you all

- Daniel

--- Daniel Valencia <fetrovsky at yahoo.com> wrote:
> Hello
> 
> --- Charles Swiger <cswiger at mac.com> wrote:
> > pcap_dispatch() will not 
> > necessarily
> >         return  when  the  read  times out; on
> some
> > platforms, the read 
> > timeout
> >         isn't supported, and, on other platforms,
> > the timer doesn't 
> > start until
> >         at  least  one packet arrives.  This means
> 
> If I read this correctly, pcap will sometimes wait
> forever until a packet appears, which I don't
> actually
> mind because it's actually the behaviour that I'm
> expecting.  What is really odd is that even when
> packets ARE arriving, pcap_loop just sits there,
> lets
> the packets pile up, and then shows all the messages
> at once... then it blocks again for a while, even as
> I
> send messages from the other computer, just to show
> them all at once again, and so on...
> 
> > you'll probably find yourself either going
> > multithreaded or using 
> 
> I'm actually going multithreaded, but I'd expect a
> packet to show up immediately, so I can process it
> and
> perform the routing in a timely manner, rather than
> delivering a packet a minute after it was sent.
> 
> Thank you very much!
> 
> - Daniel
> 
> 
> 
> 		
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