Needed to push const changes

samples/main-packet-printer.cc

@@ -1,4 +1,24 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2006,2007 INRIA
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
+ */
+
 #include "ns3/packet.h"
 #include "ns3/header.h"
 #include "ns3/packet-printer.h"
@@ -7,6 +27,23 @@
 
 using namespace ns3;
 
+// This sample file shows how to use the Packet metadata facility
+//
+// Packets are stored as ``packed'' data structures, to facilitate
+// fragmentation and network emulation.  However, when debugging a program,
+// or for certain tracing applications, it may be convenient to dump out
+// the contents of a packet header in a human-friendly form.
+//
+// To do this, a few things are needed:
+// i) enable the metadata facility (disabled by default, because it causes
+//    a small performance hit 
+// ii) decide on whether you want to use a default or customized (you
+//     provide your own) routine to dump a particular header
+//
+// This sample steps through two routines; one to use the default
+// printing of IPv4 and UDP headers, and one to show a non-default case.
+// There is a lot of emphasis in this sample of how this facility
+// interacts with packet fragmentation.
 
 void DefaultPrint (void)
 {
@@ -19,10 +56,12 @@ void DefaultPrint (void)
   ipv4.SetDestination (Ipv4Address ("192.168.0.2"));
   udp.SetSource (1025);
   udp.SetDestination (80);
+  udp.SetPayloadSize (1000);
   p.AddHeader (udp);
   p.AddHeader (ipv4);
 
   std::cout << "full packet size=" << p.GetSize () << std::endl;
+  // Here, invoke the default Print routine, directed to std out
   p.Print (std::cout);
   std::cout << std::endl;
 
@@ -51,6 +90,9 @@ void DefaultPrint (void)
   std::cout << std::endl;
 }
 
+// The below functions are used in place of default versions, in the
+// non-default case below.  For instance, DoPrintIpv4Header will print
+// out less IPv4 header information than the default print function
 void 
 DoPrintDefault (std::ostream &os,uint32_t packetUid, uint32_t size, 
                 std::string &name, struct PacketPrinter::FragmentInformation info)
@@ -75,6 +117,9 @@ DoPrintIpv4HeaderFragment (std::ostream &os, uint32_t packetUid, uint32_t size,
   os << "IPV4 fragment";
 }
 
+// This function walks through a non-default case.  A few features of
+// the API (defined in common/packet-printer.h) are shown.
+//
 void NonDefaultPrint (void)
 {
   // create an adhoc packet printer.
@@ -103,6 +148,7 @@ void NonDefaultPrint (void)
   ipv4.SetDestination (Ipv4Address ("192.168.0.2"));
   udp.SetSource (1025);
   udp.SetDestination (80);
+  udp.SetPayloadSize (1000);
   p.AddHeader (udp);
   p.AddHeader (ipv4);
 
@@ -141,8 +187,10 @@ int main (int argc, char *argv[])
 {
   Packet::EnableMetadata ();
 
+  std::cout << "DefaultPrint()" << std::endl;
   DefaultPrint ();
 
+  std::cout << std::endl << "NonDefaultPrint()" << std::endl;
   NonDefaultPrint ();
 
   return 0;