nrg_packet.h

/*
  LibNRG - Networking for Real-time Games
  
  Copyright (C) 2012-2014 Alex Baines <alex@abaines.me.uk>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
/* @file
 * Contains functionality related to the Packet class, which stores data sent / received over the network
 */
#ifndef NRG_PACKET_H
#define NRG_PACKET_H
#include "nrg_core.h"
#include "nrg_config.h"
#include "nrg_netaddress.h"
#include "nrg_endian.h"
#include <cstring> // memcpy
#include <cstdio> // SEEK_x
#include <algorithm>

namespace nrg {

struct PacketReadable {
    virtual PacketReadable& read8(uint8_t& v) = 0;   
    virtual PacketReadable& read16(uint16_t& v) = 0; 
    virtual PacketReadable& read32(uint32_t& v) = 0; 
    virtual PacketReadable& read64(uint64_t& v) = 0; 
    virtual PacketReadable& readArray(uint8_t* v, size_t size) = 0; 
    virtual ~PacketReadable(){} 
};

struct PacketWritable {
    virtual PacketWritable& write8(const uint8_t& v) = 0;   
    virtual PacketWritable& write16(const uint16_t& v) = 0; 
    virtual PacketWritable& write32(const uint32_t& v) = 0; 
    virtual PacketWritable& write64(const uint64_t& v) = 0; 
    virtual PacketWritable& writeArray(const void* v, size_t size) = 0; 
    virtual ~PacketWritable(){} 
};

class Packet : public PacketReadable, public PacketWritable {
public:
    Packet();
    
    Packet(size_t initial_size);
    
    Packet(const Packet& copy);
    
    Packet& operator=(const Packet& other);
    
    virtual ~Packet();

    PacketWritable& write8(const uint8_t& v);
    PacketWritable& write16(const uint16_t& v);
    PacketWritable& write32(const uint32_t& v);
    PacketWritable& write64(const uint64_t& v);
    PacketWritable& writeArray(const void* v, size_t size);

    template<typename T>
    void writeBE(const T& be_v){
        while((size_t)(pointer - data) > (data_size - sizeof(be_v))){
            resize();
        }
        memcpy(pointer, &be_v, sizeof(be_v));
        pointer += sizeof(be_v);
        used_size = std::max(used_size, (size_t)(pointer - data));
    }

    template<typename T>
    void write(const T& v){
        writeBE(nrg::hton(v));
    }

    PacketReadable& read8(uint8_t& v);
    PacketReadable& read16(uint16_t& v);
    PacketReadable& read32(uint32_t& v);
    PacketReadable& read64(uint64_t& v);
    PacketReadable& readArray(uint8_t* v, size_t size);

    template<typename T>
    void readBE(T& be_v){
        if((size_t)(pointer - data) <= (used_size - sizeof(be_v))){
            memcpy(&be_v, pointer, sizeof(be_v));
            pointer += sizeof(be_v);
        }
    }

    template<typename T>
    void read(T& v){
        T be = 0;
        readBE(be);
        v = nrg::ntoh(be);
    }

    virtual Packet& reset();
    
    Packet& seek(off_t offset, int whence);
    
    off_t tell() const;
    
    size_t size() const { return used_size; }
    
    size_t remaining() const { return used_size - (pointer - data); }
    
    const uint8_t* getPointer() const { return pointer; }
    
    const uint8_t* getBasePointer() const { return data; }
private:
    void resize();
    uint8_t *data, *pointer;
    size_t data_size, used_size;
};

struct PacketTransformation {
    virtual bool apply(Packet& in, Packet& out) = 0;
    virtual bool remove(Packet& in, Packet& out) = 0;
};

#ifdef NRG_ENABLE_ZLIB_COMPRESSION

struct PacketCompressor : PacketTransformation {
    virtual bool apply(Packet& in, Packet& out);
    virtual bool remove(Packet& in, Packet& out);
};

#endif

}

#endif