Add VXLAN support (#501)

This patch adds a new PDU class to support VXLAN. Several VXLAN-related
tests have also been added.

Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>

include/tins/pdu.h

@@ -180,6 +180,7 @@ public:
         PKTAP,
         MPLS,
         DOT11_CONTROL_TA,
+        VXLAN,
         UNKNOWN = 999,
         USER_DEFINED_PDU = 1000
     };

include/tins/tins.h

@@ -78,7 +78,7 @@
 #include <tins/pdu_allocator.h>
 #include <tins/ipsec.h>
 #include <tins/ip_reassembler.h>
-
 #include <tins/pdu_iterator.h>
+#include <tins/vxlan.h>
 
 #endif // TINS_TINS_H

include/tins/vxlan.h

@@ -0,0 +1,98 @@
+#ifndef TINS_VXLAN_H
+#define TINS_VXLAN_H
+
+#include <tins/pdu.h>
+#include <tins/small_uint.h>
+
+namespace Tins {
+
+/** 
+ * \class VXLAN
+ * \brief Represents a VXLAN PDU.
+ *
+ * This class represents a VXLAN PDU.
+ *
+ * \sa RawPDU
+ */
+class TINS_API VXLAN : public PDU {
+public:
+    /**
+     * \brief This PDU's flag.
+     */
+    static const PDU::PDUType pdu_flag = PDU::VXLAN;
+
+    /**
+     * \brief Constructs a VXLAN PDU.
+     *
+     * \param vni VXLAN Network Identifier.
+     */
+    VXLAN(const small_uint<24> vni = 0);
+
+    /**
+     * \brief Constructs a VXLAN object from a buffer and adds
+     * the Ethernet II PDU.
+     *
+     * \param buffer The buffer from which this PDU will be constructed.
+     * \param total_sz The total size of the buffer.
+     */
+    VXLAN(const uint8_t* buffer, uint32_t total_sz);
+
+    /**
+     * \brief Getter for the flags.
+     */
+    uint8_t get_flags() const { return Endian::be_to_host(header_.flags) >> 24; }
+
+    /**
+     * \brief Getter for the VNI.
+     */
+    small_uint<24> get_vni() const { return Endian::be_to_host(header_.vni) >> 8; }
+
+    /**
+     * \brief Setter for the flags.
+     * \param new_flags The new flags.
+     */
+    void set_flags(uint8_t new_flags) { header_.flags = Endian::host_to_be(new_flags << 24); }
+
+    /**
+     * \brief Setter for the VNI.
+     * \param new_vni The new VNI.
+     */
+    void set_vni(small_uint<24> new_vni) { header_.vni = Endian::host_to_be(new_vni << 8); }
+
+    /**
+     * \brief Returns the VXLAN frame's header length.
+     * 
+     * This method overrides PDU::header_size. This size includes the
+     * payload and options size.
+     *
+     * \return An uint32_t with the header's size.
+     * \sa PDU::header_size
+     */
+    uint32_t header_size() const { return sizeof(header_); }
+
+    /**
+     * \brief Getter for the PDU's type.
+     * \sa PDU::pdu_type
+     */
+    PDUType pdu_type() const { return pdu_flag; }
+
+    /**
+     * \sa PDU::clone
+     */
+    VXLAN *clone() const { return new VXLAN(*this); }
+
+private:
+    TINS_BEGIN_PACK
+    struct vxlan_header {
+        uint32_t flags;
+        uint32_t vni;
+    } TINS_END_PACK;
+
+    void write_serialization(uint8_t* buffer, uint32_t total_sz);
+
+    vxlan_header header_;
+};
+
+} // Tins
+
+#endif // TINS_VXLAN_H