[Click] Handlers

[Michael Voorhaen]

The problem seems to happen in this piece of the code (from
etherAddress.cc):

String
EtherAddress::unparse() const
{
  char buf[24];
  const unsigned char *p = this->data();
  sprintf(buf, "%02x:%02x:%02x:%02x:%02x:%02x",
	  p[0], p[1], p[2], p[3], p[4], p[5]);
  return String(buf, 17);
}

When i print out the value of buf, it shows the correct value. But
something seems to go wrong when you convert to String. At least on my pc
it does. The problem with the EtherEncap handlers isn't that big a deal,
if necessary I'll write the necessary code myself. So the problem is
definitely in String. I'm going to check that code out myself today, but
any help is appreciated.

Regards,
Michael.

On Tue, 3 Feb 2004, Douglas S. J. De Couto wrote:

> Hi Michael,
>
> Sorry, I started looking at your grid/nsclick problem, but then got
> swamped.
>
> I use EtherAddress all the time, and haven't seen any problem with its
> s() method, perhaps you can send an example of the problem?
>
> Can you describe the seg fault with more detail -- where does it occur?
>
> The general approach you describe seems like it should work, although
> you might get better performance by writing the ethernet destination
> address in your own element (which is what Grid/DSDV does), or using a
> more ARP-like element (either the click IP ARP elements, or something
> like the Grid DSRArpTable).  The EtherEncap element isn't designed to
> be very dynamic, but you could write one like it with set_dest() and
> set_src() C++ methods that your element could call directly.
>
> On 3 Feb 2004, at 11:15, Michael Voorhaen wrote:
>
> > Hi,
> >
> > I sent an e-mail last week, stating that I had problems compiling grid
> > for
> > nsclick and haven't seen an answer yet.
> >
> > I've skipped getting grid to work for a while and started implementing
> > the
> > hierarchical protocol that I've been working on (based on hierarchical
> > state
> > routing). Basically to concept is to implement the hierarchical
> > protocol on
> > top of a (slightly modified) flat routing protocol. I've started
> > implementing this top down, so I only needed some stubs where the flat
> > protocol is required and I can debug that software as quick as
> > possible. Now
> > somewhere in my click graph I have this situation:
> >
> > 	[GetNextHop] 	----> 0: [EtherEncap]
> > 			 	---->	1: [Discard]
> >
> > The GetNextHop element is one that I implemented. It determines the
> > next hop
> > for the packet (stub code for now). Now what I want to happen than is
> > that
> > EtherEncap encapsulates the IP packet with the correct destination
> > Ethernet
> > address in the Ethernet header. So for that I need to pass the next hop
> > Ethernet address to EtherEncap. I want to do this with handlers, so I
> > gave
> > EtherEncap a name and obtained a pointer to it in the GetNextHop code.
> > So
> > far so good. I then get the handler object "dst":
> >
> > In GetNextHop.push();
> > 		This->router()->handler("dst", _etherEncap);
> >
> > _etherEncap points to the EtherEncap object.
> >
> > This gets me the handler, and then I call call_write(
> > next_hop_ether.s(),
> > _etherEncap,_errh);
> >
> > This causes a segmentation fault.
> >
> > Now I've been trying to narrow down the problems and I found this:
> > 	* there is something wrong with how EtherAddress creates the string
> > representation of the address (check it out, if you have the time).
> > 	* even when I replace next_hop_ether.s() (which is not computed
> > correctly) with an actual ethernet address that works when manually
> > configured in a click file, I still get the segmentation fault.
> >
> > I could really use some help here. By the way, I'm using the CVS
> > version of
> > click.
> >
> > Regards,
> > Michael Voorhaen
> >
> > ========================================================
> > Michael Voorhaen
> > ========================================================
> > Phd Student
> > Dept. of Mathematics and Computer Sciences
> > PATS (Performance Analysis of Telecommunication Systems)
> > University of Antwerp
> > Middelheimlaan 1
> > 2020 Antwerpen, Belgium
> > G1.11
> > Phone: 03/2653905
> > Mail: michael.voorhaen at ua.ac.be
> > ========================================================
> >
> >
> >
> > _______________________________________________
> > click mailing list
> > click at amsterdam.lcs.mit.edu
> > https://amsterdam.lcs.mit.edu/mailman/listinfo/click
> >
> --
> Douglas S. J. De Couto    <decouto at csail.mit.edu>
>
>