Separate address assignment from routing in PointToPoint topology code

examples/simple-p2p.cc

@@ -122,16 +122,25 @@ int main (int argc, char *argv[])
   PointToPointTopology::AddIpv4Addresses (
       channel0, n0, Ipv4Address("10.1.1.1"),
       n2, Ipv4Address("10.1.1.2"));
-  channel0->Unref ();
   
   PointToPointTopology::AddIpv4Addresses (
       channel1, n1, Ipv4Address("10.1.2.1"),
       n2, Ipv4Address("10.1.2.2"));
-  channel1->Unref ();
   
   PointToPointTopology::AddIpv4Addresses (
       channel2, n2, Ipv4Address("10.1.3.1"),
       n3, Ipv4Address("10.1.3.2"));
+
+  // Finally, we add static routes.  These three steps (Channel and
+  // NetDevice creation, IP Address assignment, and routing) are 
+  // separated because there may be a need to postpone IP Address
+  // assignment (emulation) or modify to use dynamic routing
+  PointToPointTopology::AddIpv4Routes(n0, n2, channel0);
+  PointToPointTopology::AddIpv4Routes(n1, n2, channel1);
+  PointToPointTopology::AddIpv4Routes(n2, n3, channel2);
+
+  channel0->Unref ();
+  channel1->Unref ();
   channel2->Unref ();
 
   // Create the OnOff application to send UDP datagrams of size

src/devices/p2p/p2p-topology.cc

@@ -24,6 +24,8 @@
 
 #include <algorithm>
 #include "ns3/assert.h"
+#include "ns3/debug.h"
+#include "ns3/fatal-error.h"
 
 #include "ns3/nstime.h"
 
@@ -62,7 +64,7 @@ PointToPointTopology::AddPointToPointLink(
   return channel;
 }
 
-bool
+void
 PointToPointTopology::AddIpv4Addresses(
   const PointToPointChannel *chan,
   Node* n1, const Ipv4Address& addr1,
@@ -101,15 +103,82 @@ PointToPointTopology::AddIpv4Addresses(
   ip2->SetNetworkMask (index2, netmask);
   ip2->SetUp (index2);
   
-  ip1->AddHostRouteTo (addr2, index1);
-  ip2->AddHostRouteTo (addr1, index2);
-  
   ip1->Unref ();
   ip2->Unref ();
   
-  return true;
 }
 
+void
+PointToPointTopology::AddIpv4Routes (
+  Node* n1, Node* n2, const PointToPointChannel* chan)
+{ 
+  // The PointToPoint channel is used to find the relevant NetDevices
+  NS_ASSERT (chan->GetNDevices () == 2);
+  NetDevice* nd1 = chan->GetDevice (0);
+  NetDevice* nd2 = chan->GetDevice (1);
+  // XXX nd1, nd2 should be reference counted
+
+  // Assert that n1 is the Node owning one of the two NetDevices
+  // and make sure that nd1 corresponds to it
+  if (nd1->PeekNode ()->GetId () == n1->GetId ()) 
+    {
+      ; // Do nothing
+    }
+  else if (nd2->PeekNode ()->GetId () == n1->GetId ())
+    { 
+      std::swap(nd1, nd2);
+    }
+  else
+    {
+      NS_FATAL_ERROR("P2PTopo:  Node does not contain an interface on Channel");
+    }
+
+  // Assert that n2 is the Node owning one of the two NetDevices
+  // and make sure that nd2 corresponds to it
+  if (nd2->PeekNode ()->GetId () != n2->GetId ()) 
+    {
+      NS_FATAL_ERROR("P2PTopo:  Node does not contain an interface on Channel");
+    }
+
+  // Assert that both are Ipv4 nodes
+  IIpv4 *ip1 = nd1->PeekNode ()->QueryInterface<IIpv4> (IIpv4::iid);
+  IIpv4 *ip2 = nd2->PeekNode ()->QueryInterface<IIpv4> (IIpv4::iid);
+  NS_ASSERT(ip1 && ip2);
+
+  // Get interface indexes for both nodes corresponding to the right channel
+  uint32_t index1 = 0;
+  bool found = false;
+  for (uint32_t i = 0; i < ip1->GetNInterfaces (); i++)
+    {
+      if (ip1 ->PeekNetDevice (i) == nd1) 
+        {
+          index1 = i;
+          found = true;
+        }
+    }
+  NS_ASSERT(found);
+
+  uint32_t index2 = 0;
+  found = false;
+  for (uint32_t i = 0; i < ip2->GetNInterfaces (); i++)
+    {
+      if (ip2 ->PeekNetDevice (i) == nd2) 
+        {
+          index2 = i;
+          found = true;
+        }
+    }
+  NS_ASSERT(found);
+  
+  ip1->AddHostRouteTo (ip2-> GetAddress (index2), index1);
+  ip2->AddHostRouteTo (ip1-> GetAddress (index1), index2);
+  
+  ip1->Unref ();
+  ip2->Unref ();
+
+}
+
+
 #ifdef NOTYET
 
 // Get the net device connecting node n1 to n2.  For topologies where

src/devices/p2p/p2p-topology.h

@@ -33,30 +33,51 @@ class Node;
 class IPAddr;
 class DataRate;
 class Queue;
-//class Time;
 
 /**
- * \brief A helper class to create Topologies based on the ns3::PointToPointNetDevice and 
- *        ns3::PointToPointChannel objects.
- *
- * XXX ??
- * I think that some of the methods below are not implemented.
- * If so, remove them.
+ * \brief A helper class to create Topologies based on the 
+ * ns3::PointToPointNetDevice and  ns3::PointToPointChannel objects.
  */
 class PointToPointTopology {
 public:
   /** 
+   * \param n1 Node
+   * \param n2 Node
+   * \param rate Maximum transmission link rate 
+   * \param delay one-way propagation delay 
+   * \return Pointer to the underlying PointToPointChannel
+   * 
    * Add a full-duplex point-to-point link between two nodes
-   * with the specified IP addresses,  with specified maximum transmission rate
-   * and propagation delay.
+   * and attach PointToPointNetDevices to the resulting
+   * PointToPointChannel.  
    */
   static PointToPointChannel* AddPointToPointLink(
-    Node*, Node*, const DataRate&, const Time&);
+    Node* n1, Node* n2, const DataRate& rate, const Time& delay);
 
-  static bool AddIpv4Addresses(
-    const PointToPointChannel*,
-    Node*, const Ipv4Address&,
-    Node*, const Ipv4Address&);
+  /** 
+   * \param chan PointToPointChannel to use
+   * \param n1 Node
+   * \param addr1 Ipv4 Address for n1
+   * \param n2 Node
+   * \param addr2 Ipv4 Address for n2
+   * 
+   * Add Ipv4Addresses to the Ipv4 interfaces associated with the 
+   * two PointToPointNetDevices on the provided PointToPointChannel
+   */
+  static void AddIpv4Addresses(
+    const PointToPointChannel* chan,
+    Node* n1, const Ipv4Address& addr1,
+    Node* n2, const Ipv4Address& addr2);
+
+  /**
+   * \param chan PointToPointChannel to use
+   * \param n1 Node
+   * \param n2 Node
+   * 
+   * For the given PointToPointChannel, for each Node, add an 
+   * IPv4 host route to the IPv4 address of the peer node.  
+   */
+  static void AddIpv4Routes (Node*, Node*, const PointToPointChannel*);
 
   /**
    * Get the connecting node n1 to node n2

src/internet-node/i-ipv4-impl.cc

@@ -20,6 +20,7 @@
  */
 #include "i-ipv4-impl.h"
 #include "ipv4.h"
+#include "ipv4-interface.h"
 #include "ns3/assert.h"
 
 namespace ns3 {
@@ -99,6 +100,11 @@ IIpv4Impl::GetNInterfaces (void)
 {
   return m_ipv4->GetNInterfaces ();
 }
+NetDevice*
+IIpv4Impl::PeekNetDevice (uint32_t i)
+{
+  return m_ipv4->GetInterface (i)-> PeekDevice();
+}
 
 void 
 IIpv4Impl::SetAddress (uint32_t i, Ipv4Address address)

src/internet-node/i-ipv4-impl.h

@@ -53,6 +53,7 @@ public:
   virtual void RemoveRoute (uint32_t i);
   virtual uint32_t AddInterface (NetDevice *device);
   virtual uint32_t GetNInterfaces (void);  
+  virtual NetDevice* PeekNetDevice(uint32_t i);
 
   virtual void SetAddress (uint32_t i, Ipv4Address address);
   virtual void SetNetworkMask (uint32_t i, Ipv4Mask mask);

src/node/i-ipv4.h

@@ -122,6 +122,11 @@ public:
    */
   virtual uint32_t GetNInterfaces (void) = 0;  
 
+  /**
+   * Return address of the NetDevice associated with the Ipv4Interface
+   */
+  virtual NetDevice* PeekNetDevice (uint32_t i) = 0;
+
   virtual void SetAddress (uint32_t i, Ipv4Address address) = 0;
   virtual void SetNetworkMask (uint32_t i, Ipv4Mask mask) = 0;
   virtual Ipv4Mask GetNetworkMask (uint32_t t) const = 0;