network: Add a GetUint8Value method to the QueueItem class

src/internet/model/ipv4-queue-disc-item.cc

@@ -79,4 +79,20 @@ Ipv4QueueDiscItem::Print (std::ostream& os) const
   ;
 }
 
+bool
+Ipv4QueueDiscItem::GetUint8Value (QueueItem::Uint8Values field, uint8_t& value) const
+{
+  bool ret = false;
+
+  switch (field)
+    {
+    case IP_DSFIELD:
+      value = m_header.GetTos ();
+      ret = true;
+      break;
+    }
+
+  return ret;
+}
+
 } // namespace ns3

src/internet/model/ipv4-queue-disc-item.h

@@ -70,6 +70,15 @@ public:
    */
   virtual void Print (std::ostream &os) const;
 
+  /*
+   * The values for the fields of the Ipv4 header are taken from m_header and
+   * thus might differ from those present in the packet in case the header is
+   * modified after being added to the packet. However, this function is likely
+   * to be called before the header is added to the packet (i.e., before the
+   * packet is dequeued from the queue disc)
+   */
+  virtual bool GetUint8Value (Uint8Values field, uint8_t &value) const;
+
 private:
   /**
    * \brief Default constructor

src/internet/model/ipv6-queue-disc-item.cc

@@ -79,4 +79,20 @@ Ipv6QueueDiscItem::Print (std::ostream& os) const
   ;
 }
 
+bool
+Ipv6QueueDiscItem::GetUint8Value (QueueItem::Uint8Values field, uint8_t& value) const
+{
+  bool ret = false;
+
+  switch (field)
+    {
+    case IP_DSFIELD:
+      value = m_header.GetTrafficClass ();
+      ret = true;
+      break;
+    }
+
+  return ret;
+}
+
 } // namespace ns3

src/internet/model/ipv6-queue-disc-item.h

@@ -70,6 +70,15 @@ public:
    */
   virtual void Print (std::ostream &os) const;
 
+  /*
+   * The values for the fields of the Ipv6 header are taken from m_header and
+   * thus might differ from those present in the packet in case the header is
+   * modified after being added to the packet. However, this function is likely
+   * to be called before the header is added to the packet (i.e., before the
+   * packet is dequeued from the queue disc)
+   */
+  virtual bool GetUint8Value (Uint8Values field, uint8_t &value) const;
+
 private:
   /**
    * \brief Default constructor

src/network/model/net-device.cc

@@ -53,6 +53,12 @@ QueueItem::GetPacketSize (void) const
   return m_packet->GetSize ();
 }
 
+bool
+QueueItem::GetUint8Value (QueueItem::Uint8Values field, uint8_t& value) const
+{
+  return false;
+}
+
 void
 QueueItem::Print (std::ostream& os) const
 {

src/network/model/net-device.h

@@ -78,6 +78,24 @@ public:
    */
   virtual uint32_t GetPacketSize (void) const;
 
+  /**
+   * \enum Uint8Values
+   * \brief 1-byte fields of the packet whose value can be retrieved, if present
+   */
+  enum Uint8Values
+    {
+      IP_DSFIELD
+    };
+
+  /**
+   * \brief Retrieve the value of a given field from the packet, if present
+   * \param field the field whose value has to be retrieved
+   * \param value the output parameter to store the retrieved value
+   *
+   * \return true if the requested field is present in the packet, false otherwise.
+   */
+  virtual bool GetUint8Value (Uint8Values field, uint8_t &value) const;
+
   /**
    * \brief Print the item contents.
    * \param os output stream in which the data should be printed.