CookieJar.hpp

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/*
    Copyright (c) 2009-2010 Christopher A. Taylor.  All rights reserved.

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    modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
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      to endorse or promote products derived from this software without
      specific prior written permission.

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    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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    ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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#ifndef CAT_COOKIE_JAR_HPP
#define CAT_COOKIE_JAR_HPP

#include <cat/crypt/rand/Fortuna.hpp>

namespace cat {


class CookieJar
{
    static const int EXPIRE_TIME = 4000; // ms
    static const int BIN_COUNT = 16; // power of 2
    static const int BIN_TIME = EXPIRE_TIME / BIN_COUNT;
    static const int BIN_MASK = BIN_COUNT - 1;

    u32 key[16];

    u32 Salsa6(u32 *x);

    u32 Hash(u32 ip, u16 port, u32 epoch);
    u32 Hash(const void *address_info, int bytes, u32 epoch);

    u32 GetEpoch();
    u32 ReconstructEpoch(u32 cookie);

public:
    // Initialize to a random 512-bit key on startup
    void Initialize(FortunaOutput *csprng);

    // Thread-safe and lock-free
    u32 Generate(u32 ip, u16 port);
    u32 Generate(const void *address_info, int bytes); // bytes <= 48

    // Thread-safe and lock-free
    bool Verify(u32 ip, u16 port, u32 cookie);
    bool Verify(const void *address_info, int bytes, u32 cookie); // bytes <= 48
};


} // namespace cat

#endif // CAT_COOKIE_JAR_HPP