[Click] How to add new information to ns trace files.

[Michael Voorhaen]

Hi,

I am trying to modify nsclick to allow me to add trace information to 
the ns trace files from any click element. I have looked through the 
interface code between ns and click and added a new function to simclick.h:

int simclick_sim_trace(simclick_sim simins, simclick_click clickinst, 
const unsigned char* data, const char* logentry);

This function is then implemented in classifier-click.cc. So right now 
I've gotten up to the point where I can send the information that needs 
to be traced to ns2. But when I configure my ClickClassifier with a 
Trace object and try to add something to the trace, I keep getting 
segmentation faults. I suspect this is because the object I am getting 
from my ns configuration script is not a Trace object or at least not a 
correct one. Since if I create the a trace object in the c++ code I 
don't get the segmentation faults.

I've copied the relevant code snippets below. I started from the dsr 
code as an example of how to add new trace information to the trace 
files. When trying to add something I get the following  error:

ClickClassifier: after va_start 85ec488 2

Program received signal SIGSEGV, Segmentation fault.
0x0805c7e2 in BaseTrace::buffer (this=0x2) at basetrace.h:50
50      basetrace.h: No such file or directory.
        in basetrace.h

In fact the logtarget_ (see below) points to some object, but 
logtarget_->pt_  points to 2. Which is weird since a trace object 
creates a basetrace object in it's constructor. Can someone help me with 
this problem. I guess that I am doing something wrong in my tcl script, 
but the documentation on this is so vague. I've tried a lot of thing but 
I don't see any solution.

Best Regards,
Michael

Code snippets below:

In classifier-click.cc

    if(strcmp(argv[1], "tracetarget") == 0) {
      printf("ClickClassifier: tracetarget called\n");
      logtarget_ = (Trace *) argv[2];
      return TCL_OK;
    }

---------------------

In classifier-click.cc

int
simclick_sim_trace(simclick_sim siminst, simclick_click clickinst, const 
unsigned char* data, const char* logentry) {
  //printf("classifier-click.cc: need to implement simclick_sim_trace\n");
  ClickClassifier* theclassifier = (ClickClassifier*)siminst;
  theclassifier->trace("t");
  return 1;
}

------------------------------

In classifier-click.cc

void
ClickClassifier::trace(char* fmt, ...)
{
  va_list ap;
 
  printf("ClickClassifier: start\n");
 
  if (!logtarget_) {
      printf("ClickClassifier: need to configure tracetarget\n");
      return;
  }
  printf("ClickClassifier: after !logtarget_\n");
  va_start(ap, fmt);
  printf("ClickClassifier: after va_start %x %x \n", logtarget_, 
logtarget_->pt_);
  vsprintf(logtarget_->pt_->buffer(), fmt, ap);
  printf("ClickClassifier: after vs_printf\n");
  logtarget_->pt_->dump();
  printf("ClickClassifier: after dump\n");
  va_end(ap);
  printf("ClickClassifier: after va_end\n");
}

----------------------------

in the ns script:

    set T [new Trace/Generic]
    $T target [$ns_ set nullAgent_]
    $T attach $tracefd
    $T set src_ [$node_bb_($i) id]
    [$node_bb_($i) entry] tracetarget $T
    [$node_bb_($i) entry] loadclick "olsr_2int.click"