vanetrbc_header.h

基于NS-2的车辆Ad Hoc网络（VANET）的一个应用层协议框架

/* -------------------------------------------------------------------
 * Vehicular Ad Hoc Networks: Regular Broadcasting of messages.
 * Skeleton for VANET-protocols. This should be considered as an
 * example to create other VANET protocols!
 * Apart from channel load, the "protocol" as it is now does not do
 * anything useful.
 *
 * Dan Jungels ([e-mail])
 * LCA - EPFL
 *
 *
 * Packet Headers for the protocol
 * Originally written for ns2.29
 *
 * 2005-12-15: release of first version (dj)
 * 2005-12-23: update and cleanup, public release (dj)
 * 2006-01-05: bugfix in the packet header (dj)
 * ------------------------------------------------------------------- */

#ifndef vanetrbc_header_h
#define vanetrbc_header_h

// Message types
#define VANETTYPE_REGBC         1
// define your own message types here

// Header Macros
#define HDR_VANET(p)        ((struct hdr_vanet*)hdr_vanet::access(p))
#define HDR_VANET_RBC(p)    ((struct hdr_vanet_rbc*)hdr_vanet::access(p))
// define the header macros for your own message types here


// general VANET header, shared by all types.
// this is an easy method to access the msgtype-variable (since you don't
// know which specific packet-header you have received, before having read
// this variable), thus preventing you from making "unknown" casts
struct hdr_vanet {
    
    u_int8_t vn_msgtype;    // type of the message (don't change!)
    
    // Header access methods (don't change!)
    static int offset_;     // required by PacketHeaderManager
    inline static int& offset() {
        return offset_;
    }
    inline static hdr_vanet* access(const Packet* p) {
        return (hdr_vanet*) p->access(offset_);
    }
    // end of Header access methods.
    
};


struct hdr_vanet_rbc {  // TYPE: Regular broadcast
    
    u_int8_t rbc_msgtype;   // type of the message (don't change!).
                            // It is mandatory to copy *first* all the
                            // variables that you use in the general header
                            // (above) to every specific header with the same
                            // type (i.e. u_int8_t), so that you don't
                            // overwrite the memory location when writing
                            // data to the specific headers! (the name may be
                            // different, a good convention is to always use
                            // a specific prefix per specific header)
    
    // here you may add or remove fields as you wish, for the specific packet
    // header
    double rbc_timestamp;   // timestamp at which the message was sent
                            // (you may change or remove this)
    u_int32_t rbc_senderID; // the sender's ID
                            // (you may change or remove this)
    
    char rbc_message[150];  // to store some data in it... (not really used
                            // for the moment. but maybe later. you may
                            // also include some cryptographic stuff, etc).
    double rbc_posx;        // sender's position
    double rbc_posy;
    
    
    // calculate the size of the header (don't remove, but update)
    inline int size() {
        // The same comment as above applies.
        int sz = sizeof(u_int8_t)       // 1 on x86
                + sizeof(double)        // 8 on x86
                + sizeof(u_int32_t)     // 4 on x86
                + 150*sizeof(char)      // ...*1 on x86
                + sizeof(double)        // 8 on x86
                + sizeof(double);       // 8 on x86
        return sz;
    }
};


// ! add your packet types here


// for size calculation of header-space reservation (don't remove!)
union hdr_all_vanet {
    hdr_vanet vh;
    hdr_vanet_rbc rbc;
    // also add you packet types here, if you have added some above
};


#endif