checkpoint tap progress

examples/csma-tap-bridge.cc

@@ -147,38 +147,17 @@ main (int argc, char *argv[])
   bridge.SetAttribute ("DeviceName", StringValue ("right"));
   bridge.Install (nodes.Get (3), devices.Get (3));
 
-#if 0
-  //
-  // Testing only -- send a packet from an internal node to an external node
-  //
-  uint32_t packetSize = 1024;
-  uint32_t maxPacketCount = 100;
-  Time interPacketInterval = Seconds (1.);
-  UdpEchoClientHelper client (interfaces.GetAddress (0), 9);
-  client.SetAttribute ("MaxPackets", UintegerValue (maxPacketCount));
-  client.SetAttribute ("Interval", TimeValue (interPacketInterval));
-  client.SetAttribute ("PacketSize", UintegerValue (packetSize));
-  ApplicationContainer apps = client.Install (nodes.Get (1));
-  apps.Start (Seconds (2.0));
-  apps.Stop (Seconds (10.0));
-#endif
-
   //
   // Configure tracing of all enqueue, dequeue, and NetDevice receive events.
   //
-#if 0
   NS_LOG_INFO ("Configure Tracing.");
-  std::ofstream ascii;
-  ascii.open ("csma-tap-bridge.tr");
-  CsmaHelper::EnableAsciiAll (ascii);
   CsmaHelper::EnablePcapAll ("csma-tap-bridge");
-#endif
 
   //
   // Now, do the actual simulation.  Run for a few minutes to allow the user a chance
   // to run some applications on the Linux hosts.
   //
-  Simulator::Stop (Seconds (3. * 60.));
+  Simulator::Stop (Seconds (60.));
   NS_LOG_INFO ("Run Simulation.");
   Simulator::Run ();
   Simulator::Destroy ();

src/devices/tap-bridge/tap-bridge.cc

@@ -24,6 +24,7 @@
 #include "ns3/packet.h"
 #include "ns3/ethernet-header.h"
 #include "ns3/ethernet-trailer.h"
+#include "ns3/llc-snap-header.h"
 #include "ns3/log.h"
 #include "ns3/boolean.h"
 #include "ns3/string.h"
@@ -598,22 +599,100 @@ TapBridge::ForwardToBridgedDevice (uint8_t *buf, uint32_t len)
   buf = 0;
 
   //
-  // Checksum the packet
+  // Make sure the packet we received is reasonable enough for the rest of the 
+  // system to handle and get it ready to be injected directly into an ns-3
+  // device.  What should come back is a packet with the Ethernet header 
+  // (and possibly an LLC header as well) stripped off.
   //
-  EthernetTrailer trailer;
-  packet->RemoveTrailer (trailer);
-  trailer.CheckFcs (packet);
+  Address src, dst;
+  uint16_t type;
+
+  NS_LOG_LOGIC ("Received packet from tap device");
+
+  Ptr<Packet> p = Filter (packet, &src, &dst, &type);
+  if (p == 0)
+    {
+      NS_LOG_LOGIC ("Discarding packet as unfit for ns-3 consumption");
+      return;
+    }
+
+  NS_LOG_LOGIC ("Pkt source is " << src);
+  NS_LOG_LOGIC ("Pkt destination is " << dst);
+  NS_LOG_LOGIC ("Pkt LengthType is " << type);
+
+  NS_LOG_LOGIC ("Forwarding packet");
+  m_bridgedDevice->SendFrom (packet, src, dst, type);
+}
+
+Ptr<Packet>
+TapBridge::Filter (Ptr<Packet> p, Address *src, Address *dst, uint16_t *type)
+{
+  NS_LOG_FUNCTION (p);
+  uint32_t pktSize;
 
   //
-  // Get rid of the MAC header
+  // We have a candidate packet for injection into ns-3.  We expect that since
+  // it came over a socket that provides Ethernet packets, it sould be big 
+  // enough to hold an EthernetTrailer.  If it can't, we signify the packet 
+  // should be filtered out by returning 0.
   //
+  pktSize = p->GetSize ();
+  EthernetTrailer trailer;
+  if (pktSize < trailer.GetSerializedSize ())
+    {
+      return 0;
+    }
+  p->RemoveTrailer (trailer);
+
+  //
+  // We also expect that it will have an Ethernet header on it.
+  //
+  pktSize = p->GetSize ();
   EthernetHeader header (false);
-  packet->RemoveHeader (header);
+  if (pktSize < header.GetSerializedSize ())
+    {
+      return 0;
+    }
+
+  p->RemoveHeader (header);
 
   NS_LOG_LOGIC ("Pkt source is " << header.GetSource ());
   NS_LOG_LOGIC ("Pkt destination is " << header.GetDestination ());
+  NS_LOG_LOGIC ("Pkt LengthType is " << header.GetLengthType ());
 
-  m_bridgedDevice->SendFrom (packet, header.GetSource (), header.GetDestination (), 0x800);
+  //
+  // If the length/type is less than 1500, it corresponds to a length 
+  // interpretation packet.  In this case, it is an 802.3 packet and 
+  // will also have an 802.2 LLC header.  If greater than 1500, we
+  // find the protocol number (Ethernet type) directly.
+  //
+  if (header.GetLengthType () <= 1500)
+    {
+      *src = header.GetSource ();
+      *dst = header.GetDestination ();
+
+      pktSize = p->GetSize ();
+      LlcSnapHeader llc;
+      if (pktSize < llc.GetSerializedSize ())
+        {
+          return 0;
+        }
+
+        p->RemoveHeader (llc);
+        *type = llc.GetType ();
+    }
+  else
+    {
+      *src = header.GetSource ();
+      *dst = header.GetDestination ();
+      *type = header.GetLengthType ();
+    }
+
+  //
+  // What we give back is a packet without the Ethernet header and trailer
+  // on it, that is fit to give directly to the bridged net device.
+  //
+  return p;
 }
 
 Ptr<NetDevice>
@@ -626,7 +705,7 @@ TapBridge::GetBridgedNetDevice (void)
 void 
 TapBridge::SetBridgedNetDevice (Ptr<NetDevice> bridgedDevice)
 {
-  NS_LOG_FUNCTION_NOARGS ();
+  NS_LOG_FUNCTION (bridgedDevice);
 
   NS_ASSERT_MSG (m_node != 0, "TapBridge::SetBridgedDevice:  Bridge not installed in a node");
   NS_ASSERT_MSG (bridgedDevice != this, "TapBridge::SetBridgedDevice:  Cannot bridge to self");

src/devices/tap-bridge/tap-bridge.h

@@ -168,8 +168,19 @@ private:
    */
   void ReadThread (void);
 
+  /*
+   * Forward a packet received from the tap device to the bridged ns-3 
+   * device
+   */
   void ForwardToBridgedDevice (uint8_t *buf, uint32_t len);
 
+  /**
+   * The host we are bridged to is in the evil real world.  Do some sanity
+   * checking on a received packet to make sure it isn't too evil for our
+   * poor naive virginal simulator to handle.
+   */
+  Ptr<Packet> Filter (Ptr<Packet> packet, Address *src, Address *dst, uint16_t *type);
+
   NetDevice::ReceiveCallback m_rxCallback;
   NetDevice::PromiscReceiveCallback m_promiscRxCallback;