ping.cc

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// Copyright (c) 2000 by the University of Southern California
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// $Header: /nfs/jade/vint/CVSROOT/ns-2/apps/ping.cc,v 1.5 2002/11/07 00:18:35 haldar Exp $

/*
 * File: Code for a new 'Ping' Agent Class for the ns
 *       network simulator
 * Author: Marc Greis (greis@cs.uni-bonn.de), May 1998
 *
 * IMPORTANT: Incase of any changes made to this file , 
 * tutorial/examples/ping.cc file (used in Greis' tutorial) should
 * be updated as well.
 */

#include "ping.h"

int hdr_ping::offset_;
static class PingHeaderClass : public PacketHeaderClass {
public:
        PingHeaderClass() : PacketHeaderClass("PacketHeader/Ping", 
                                              sizeof(hdr_ping)) {
                bind_offset(&hdr_ping::offset_);
        }
} class_pinghdr;


static class PingClass : public TclClass {
public:
        PingClass() : TclClass("Agent/Ping") {}
        TclObject* create(int, const char*const*) {
                return (new PingAgent());
        }
} class_ping;


PingAgent::PingAgent() : Agent(PT_PING)
{
        bind("packetSize_", &size_);
}

int PingAgent::command(int argc, const char*const* argv)
{
  if (argc == 2) {
    if (strcmp(argv[1], "send") == 0) {
      // Create a new packet
      Packet* pkt = allocpkt();
      // Access the Ping header for the new packet:
      hdr_ping* hdr = hdr_ping::access(pkt);
      // Set the 'ret' field to 0, so the receiving node
      // knows that it has to generate an echo packet
      hdr->ret = 0;
      // Store the current time in the 'send_time' field
      hdr->send_time = Scheduler::instance().clock();
      // Send the packet
      send(pkt, 0);
      // return TCL_OK, so the calling function knows that
      // the command has been processed
      return (TCL_OK);
    
    }
    
    else if (strcmp(argv[1], "start-WL-brdcast") == 0) {
      Packet* pkt = allocpkt();
      
      hdr_ip* iph = HDR_IP(pkt);
      hdr_ping* ph = hdr_ping::access(pkt);
      
      iph->daddr() = IP_BROADCAST;
      iph->dport() = iph->sport();
      ph->ret = 0;
      send(pkt, (Handler*) 0);
      return (TCL_OK);
    }
  }
  
  // If the command hasn't been processed by PingAgent()::command,
  // call the command() function for the base class
  return (Agent::command(argc, argv));
}


void PingAgent::recv(Packet* pkt, Handler*)
{
  // Access the IP header for the received packet:
  hdr_ip* hdrip = hdr_ip::access(pkt);
  
  // Access the Ping header for the received packet:
  hdr_ping* hdr = hdr_ping::access(pkt);
  

  // check if in brdcast mode
  if ((u_int32_t)hdrip->daddr() == IP_BROADCAST) {
    if (hdr->ret == 0) {
      
      printf("Recv BRDCAST Ping REQ : at %d.%d from %d.%d\n", here_.addr_, here_.port_, hdrip->saddr(), hdrip->sport());
      Packet::free(pkt);
      
      // create reply
      Packet* pktret = allocpkt();

      hdr_ping* hdrret = hdr_ping::access(pktret);
      hdr_cmn* ch = HDR_CMN(pktret);
      hdr_ip* ipret = hdr_ip::access(pktret);
      
      hdrret->ret = 1;
      
      // add brdcast address
      ipret->daddr() = IP_BROADCAST;
      ipret->dport() = ipret->sport();

      send(pktret, 0);
    
    } else {
      printf("Recv BRDCAST Ping REPLY : at %d.%d from %d.%d\n", here_.addr_, here_.port_, hdrip->saddr(), hdrip->sport());
      Packet::free(pkt);
    }
    return;
  }
  // Is the 'ret' field = 0 (i.e. the receiving node is being pinged)?
  if (hdr->ret == 0) {
    // Send an 'echo'. First save the old packet's send_time
    double stime = hdr->send_time;
    // Discard the packet
    Packet::free(pkt);
    // Create a new packet
    Packet* pktret = allocpkt();
    // Access the Ping header for the new packet:
    hdr_ping* hdrret = hdr_ping::access(pktret);
    // Set the 'ret' field to 1, so the receiver won't send
    // another echo
    hdrret->ret = 1;
    // Set the send_time field to the correct value
    hdrret->send_time = stime;
    // Send the packet
    send(pktret, 0);
  } else {
    // A packet was received. Use tcl.eval to call the Tcl
    // interpreter with the ping results.
    // Note: In the Tcl code, a procedure
    // 'Agent/Ping recv {from rtt}' has to be defined which
    // allows the user to react to the ping result.
    char out[100];
    // Prepare the output to the Tcl interpreter. Calculate the
    // round trip time
    sprintf(out, "%s recv %d %3.1f", name(), 
            hdrip->src_.addr_ >> Address::instance().NodeShift_[1],
            (Scheduler::instance().clock()-hdr->send_time) * 1000);
    Tcl& tcl = Tcl::instance();
    tcl.eval(out);
    // Discard the packet
    Packet::free(pkt);
  }
}

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