Drop CSMA packets with CRC errors, rescan, dox tweaks

src/node/ethernet-trailer.cc

@@ -41,7 +41,7 @@ EthernetTrailer::EnableFcs (bool enable)
 }
 
 bool
-EthernetTrailer::CheckFcs (Ptr<Packet> p) const
+EthernetTrailer::CheckFcs (Ptr<const Packet> p) const
 {
   int len = p->GetSize ();
   uint8_t *buffer;
@@ -60,7 +60,7 @@ EthernetTrailer::CheckFcs (Ptr<Packet> p) const
 }
 
 void
-EthernetTrailer::CalcFcs (Ptr<Packet> p)
+EthernetTrailer::CalcFcs (Ptr<const Packet> p)
 {
   int len = p->GetSize ();
   uint8_t *buffer;
@@ -142,7 +142,7 @@ EthernetTrailer::Deserialize (Buffer::Iterator end)
 // This code is copied from /lib/crc32.c in the linux kernel.
 // It assumes little endian ordering.
 uint32_t
-EthernetTrailer::DoCalcFcs (uint8_t *buffer, size_t len) const
+EthernetTrailer::DoCalcFcs (uint8_t const *buffer, size_t len) const
 {
   uint32_t crc = 0xffffffff;
   int i;

src/node/ethernet-trailer.h

@@ -34,8 +34,7 @@ namespace ns3 {
  * \brief Packet trailer for Ethernet
  *
  * This class can be used to add and verify the FCS at the end of an
- * ethernet packet. The actual FCS functionality is not yet coded and
- * so this acts more as a placeholder.
+ * Ethernet packet.
  */
 class EthernetTrailer : public Trailer 
 {
@@ -50,32 +49,41 @@ public:
    * \param enable If true, enables FCS calculations.
    */
   void EnableFcs (bool enable);
+
   /**
    * \brief Updates the Fcs Field to the correct FCS
    * \param p Reference to a packet on which the FCS should be
-   * calculated. The packet should not currently contain an FCS
-   * trailer.
+   * calculated. The packet should not currently contain an 
+   * EthernetTrailer.
    */
-  void CalcFcs (Ptr<Packet> p);
+  void CalcFcs (Ptr<const Packet> p);
+
   /**
    * \brief Sets the FCS to a new value
    * \param fcs New FCS value
    */
   void SetFcs (uint32_t fcs);
+
   /**
    * \return the FCS contained in this trailer
    */
   uint32_t GetFcs ();
 
   /**
-   * \param p Reference to the packet on which the FCS should be
-   * calculated. The packet should not contain an FCS trailer.
-   * \return Returns true if the packet fcs is correct, false otherwise.
+   * Calculate an FCS on the provided packet and check this value against
+   * the FCS found when the trailer was deserialized (the one in the transmitted
+   * packet).
    *
    * If FCS checking is disabled, this method will always
    * return true.
+   *
+   * \param p Reference to the packet on which the FCS should be
+   * calculated. The packet should not contain an EthernetTrailer.
+   *
+   * \return Returns true if the Packet FCS matches the FCS in the trailer, 
+   * false otherwise.
    */
-  bool CheckFcs (Ptr<Packet> p) const;
+  bool CheckFcs (Ptr<const Packet> p) const;
 
   /**
    *\return Returns the size of the trailer
@@ -90,17 +98,16 @@ public:
   virtual uint32_t Deserialize (Buffer::Iterator end);
 private:
   /**
-   * Enabled FCS calculations. If false, fcs is set to 0 and checkFCS
+   * Enabled FCS calculations. If false, m_fcs is set to 0 and CheckFcs
    * returns true.
    */
   bool m_calcFcs;
   uint32_t m_fcs; /// Value of the fcs contained in the trailer
 
-  uint32_t DoCalcFcs (uint8_t *buffer, size_t len) const;
+  uint32_t DoCalcFcs (uint8_t const *buffer, size_t len) const;
 
 };
 
 } // namespace ns3
 
-
 #endif /* ETHERNET_TRAILER_H */