secblock.h

// secblock.h - written and placed in the public domain by Wei Dai

#ifndef CRYPTOPP_SECBLOCK_H
#define CRYPTOPP_SECBLOCK_H

#include "config.h"
#include "misc.h"
#include <assert.h>

NAMESPACE_BEGIN(CryptoPP)

// ************** secure memory allocation ***************

template<class T>
class AllocatorBase
{
public:
        typedef T value_type;
        typedef size_t size_type;
#ifdef CRYPTOPP_MSVCRT6
        typedef ptrdiff_t difference_type;
#else
        typedef std::ptrdiff_t difference_type;
#endif
        typedef T * pointer;
        typedef const T * const_pointer;
        typedef T & reference;
        typedef const T & const_reference;

        pointer address(reference r) const {return (&r);}
        const_pointer address(const_reference r) const {return (&r); }
        void construct(pointer p, const T& val) {new (p) T(val);}
        void destroy(pointer p) {p->~T();}
        size_type max_size() const {return ~size_type(0)/sizeof(T);}    // switch to std::numeric_limits<T>::max later

protected:
        static void CheckSize(size_t n)
        {
                if (n > ~size_t(0) / sizeof(T))
                        throw InvalidArgument("AllocatorBase: requested size would cause integer overflow");
        }
};

#define CRYPTOPP_INHERIT_ALLOCATOR_TYPES        \
typedef typename AllocatorBase<T>::value_type value_type;\
typedef typename AllocatorBase<T>::size_type size_type;\
typedef typename AllocatorBase<T>::difference_type difference_type;\
typedef typename AllocatorBase<T>::pointer pointer;\
typedef typename AllocatorBase<T>::const_pointer const_pointer;\
typedef typename AllocatorBase<T>::reference reference;\
typedef typename AllocatorBase<T>::const_reference const_reference;

#if defined(_MSC_VER) && (_MSC_VER < 1300)
// this pragma causes an internal compiler error if placed immediately before std::swap(a, b)
#pragma warning(push)
#pragma warning(disable: 4700)  // VC60 workaround: don't know how to get rid of this warning
#endif

template <class T, class A>
typename A::pointer StandardReallocate(A& a, T *p, typename A::size_type oldSize, typename A::size_type newSize, bool preserve)
{
        if (oldSize == newSize)
                return p;

        if (preserve)
        {
                typename A::pointer newPointer = a.allocate(newSize, NULL);
                memcpy_s(newPointer, sizeof(T)*newSize, p, sizeof(T)*STDMIN(oldSize, newSize));
                a.deallocate(p, oldSize);
                return newPointer;
        }
        else
        {
                a.deallocate(p, oldSize);
                return a.allocate(newSize, NULL);
        }
}

#if defined(_MSC_VER) && (_MSC_VER < 1300)
#pragma warning(pop)
#endif

template <class T, bool T_Align16 = false>
class AllocatorWithCleanup : public AllocatorBase<T>
{
public:
        CRYPTOPP_INHERIT_ALLOCATOR_TYPES

        pointer allocate(size_type n, const void * = NULL)
        {
                CheckSize(n);
                if (n == 0)
                        return NULL;

#if CRYPTOPP_BOOL_ALIGN16_ENABLED
                if (T_Align16 && n*sizeof(T) >= 16)
                        return (pointer)AlignedAllocate(n*sizeof(T));
#endif

                return (pointer)UnalignedAllocate(n*sizeof(T));
        }

        void deallocate(void *p, size_type n)
        {
                SecureWipeArray((pointer)p, n);

#if CRYPTOPP_BOOL_ALIGN16_ENABLED
                if (T_Align16 && n*sizeof(T) >= 16)
                        return AlignedDeallocate(p);
#endif

                UnalignedDeallocate(p);
        }

        pointer reallocate(T *p, size_type oldSize, size_type newSize, bool preserve)
        {
                return StandardReallocate(*this, p, oldSize, newSize, preserve);
        }

        // VS.NET STL enforces the policy of "All STL-compliant allocators have to provide a
        // template class member called rebind".
    template <class U> struct rebind { typedef AllocatorWithCleanup<U, T_Align16> other; };
#if _MSC_VER >= 1500
        AllocatorWithCleanup() {}
        template <class U, bool A> AllocatorWithCleanup(const AllocatorWithCleanup<U, A> &) {}
#endif
};

CRYPTOPP_DLL_TEMPLATE_CLASS AllocatorWithCleanup<byte>;
CRYPTOPP_DLL_TEMPLATE_CLASS AllocatorWithCleanup<word16>;
CRYPTOPP_DLL_TEMPLATE_CLASS AllocatorWithCleanup<word32>;
CRYPTOPP_DLL_TEMPLATE_CLASS AllocatorWithCleanup<word64>;
#if CRYPTOPP_BOOL_X86
CRYPTOPP_DLL_TEMPLATE_CLASS AllocatorWithCleanup<word, true>;   // for Integer
#endif

template <class T>
class NullAllocator : public AllocatorBase<T>
{
public:
        CRYPTOPP_INHERIT_ALLOCATOR_TYPES

        pointer allocate(size_type n, const void * = NULL)
        {
                assert(false);
                return NULL;
        }

        void deallocate(void *p, size_type n)
        {
                assert(false);
        }

        size_type max_size() const {return 0;}
};

// This allocator can't be used with standard collections because
// they require that all objects of the same allocator type are equivalent.
// So this is for use with SecBlock only.
template <class T, size_t S, class A = NullAllocator<T>, bool T_Align16 = false>
class FixedSizeAllocatorWithCleanup : public AllocatorBase<T>
{
public:
        CRYPTOPP_INHERIT_ALLOCATOR_TYPES

        FixedSizeAllocatorWithCleanup() : m_allocated(false) {}

        pointer allocate(size_type n)
        {
                assert(IsAlignedOn(m_array, 8));

                if (n <= S && !m_allocated)
                {
                        m_allocated = true;
                        return GetAlignedArray();
                }
                else
                        return m_fallbackAllocator.allocate(n);
        }

        pointer allocate(size_type n, const void *hint)
        {
                if (n <= S && !m_allocated)
                {
                        m_allocated = true;
                        return GetAlignedArray();
                }
                else
                        return m_fallbackAllocator.allocate(n, hint);
        }

        void deallocate(void *p, size_type n)
        {
                if (p == GetAlignedArray())
                {
                        assert(n <= S);
                        assert(m_allocated);
                        m_allocated = false;
                        SecureWipeArray((pointer)p, n);
                }
                else
                        m_fallbackAllocator.deallocate(p, n);
        }

        pointer reallocate(pointer p, size_type oldSize, size_type newSize, bool preserve)
        {
                if (p == GetAlignedArray() && newSize <= S)
                {
                        assert(oldSize <= S);
                        if (oldSize > newSize)
                                SecureWipeArray(p+newSize, oldSize-newSize);
                        return p;
                }

                pointer newPointer = allocate(newSize, NULL);
                if (preserve)
                        memcpy(newPointer, p, sizeof(T)*STDMIN(oldSize, newSize));
                deallocate(p, oldSize);
                return newPointer;
        }

        size_type max_size() const {return STDMAX(m_fallbackAllocator.max_size(), S);}

private:
#ifdef __BORLANDC__
        T* GetAlignedArray() {return m_array;}
        T m_array[S];
#else
        T* GetAlignedArray() {return (CRYPTOPP_BOOL_ALIGN16_ENABLED && T_Align16) ? (T*)(((byte *)m_array) + (0-(size_t)m_array)%16) : m_array;}
        CRYPTOPP_ALIGN_DATA(8) T m_array[(CRYPTOPP_BOOL_ALIGN16_ENABLED && T_Align16) ? S+8/sizeof(T) : S];
#endif
        A m_fallbackAllocator;
        bool m_allocated;
};

//! a block of memory allocated using A
template <class T, class A = AllocatorWithCleanup<T> >
class SecBlock
{
public:
        typedef typename A::value_type value_type;
        typedef typename A::pointer iterator;
        typedef typename A::const_pointer const_iterator;
        typedef typename A::size_type size_type;

        explicit SecBlock(size_type size=0)
                : m_size(size) {m_ptr = m_alloc.allocate(size, NULL);}
        SecBlock(const SecBlock<T, A> &t)
                : m_size(t.m_size) {m_ptr = m_alloc.allocate(m_size, NULL); memcpy_s(m_ptr, m_size*sizeof(T), t.m_ptr, m_size*sizeof(T));}
        SecBlock(const T *t, size_type len)
                : m_size(len)
        {
                m_ptr = m_alloc.allocate(len, NULL);
                if (t == NULL)
                        memset_z(m_ptr, 0, len*sizeof(T));
                else
                        memcpy(m_ptr, t, len*sizeof(T));
        }

        ~SecBlock()
                {m_alloc.deallocate(m_ptr, m_size);}

#ifdef __BORLANDC__
        operator T *() const
                {return (T*)m_ptr;}
#else
        operator const void *() const
                {return m_ptr;}
        operator void *()
                {return m_ptr;}

        operator const T *() const
                {return m_ptr;}
        operator T *()
                {return m_ptr;}
#endif

//      T *operator +(size_type offset)
//              {return m_ptr+offset;}

//      const T *operator +(size_type offset) const
//              {return m_ptr+offset;}

//      T& operator[](size_type index)
//              {assert(index >= 0 && index < m_size); return m_ptr[index];}

//      const T& operator[](size_type index) const
//              {assert(index >= 0 && index < m_size); return m_ptr[index];}

        iterator begin()
                {return m_ptr;}
        const_iterator begin() const
                {return m_ptr;}
        iterator end()
                {return m_ptr+m_size;}
        const_iterator end() const
                {return m_ptr+m_size;}

        typename A::pointer data() {return m_ptr;}
        typename A::const_pointer data() const {return m_ptr;}

        size_type size() const {return m_size;}
        bool empty() const {return m_size == 0;}

        byte * BytePtr() {return (byte *)m_ptr;}
        const byte * BytePtr() const {return (const byte *)m_ptr;}
        size_type SizeInBytes() const {return m_size*sizeof(T);}

        //! set contents and size
        void Assign(const T *t, size_type len)
        {
                New(len);
                memcpy_s(m_ptr, m_size*sizeof(T), t, len*sizeof(T));
        }

        //! copy contents and size from another SecBlock
        void Assign(const SecBlock<T, A> &t)
        {
                if (this != &t)
                {
                        New(t.m_size);
                        memcpy_s(m_ptr, m_size*sizeof(T), t.m_ptr, m_size*sizeof(T));
                }
        }

        SecBlock<T, A>& operator=(const SecBlock<T, A> &t)
        {
                Assign(t);
                return *this;
        }

        // append to this object
        SecBlock<T, A>& operator+=(const SecBlock<T, A> &t)
        {
                size_type oldSize = m_size;
                Grow(m_size+t.m_size);
                memcpy_s(m_ptr+oldSize, m_size*sizeof(T), t.m_ptr, t.m_size*sizeof(T));
                return *this;
        }

        // append operator
        SecBlock<T, A> operator+(const SecBlock<T, A> &t)
        {
                SecBlock<T, A> result(m_size+t.m_size);
                memcpy_s(result.m_ptr, result.m_size*sizeof(T), m_ptr, m_size*sizeof(T));
                memcpy_s(result.m_ptr+m_size, t.m_size*sizeof(T), t.m_ptr, t.m_size*sizeof(T));
                return result;
        }

        bool operator==(const SecBlock<T, A> &t) const
        {
                return m_size == t.m_size && VerifyBufsEqual(m_ptr, t.m_ptr, m_size*sizeof(T));
        }

        bool operator!=(const SecBlock<T, A> &t) const
        {
                return !operator==(t);
        }

        //! change size, without preserving contents
        void New(size_type newSize)
        {
                m_ptr = m_alloc.reallocate(m_ptr, m_size, newSize, false);
                m_size = newSize;
        }

        //! change size and set contents to 0
        void CleanNew(size_type newSize)
        {
                New(newSize);
                memset_z(m_ptr, 0, m_size*sizeof(T));
        }

        //! change size only if newSize > current size. contents are preserved
        void Grow(size_type newSize)
        {
                if (newSize > m_size)
                {
                        m_ptr = m_alloc.reallocate(m_ptr, m_size, newSize, true);
                        m_size = newSize;
                }
        }

        //! change size only if newSize > current size. contents are preserved and additional area is set to 0
        void CleanGrow(size_type newSize)
        {
                if (newSize > m_size)
                {
                        m_ptr = m_alloc.reallocate(m_ptr, m_size, newSize, true);
                        memset(m_ptr+m_size, 0, (newSize-m_size)*sizeof(T));
                        m_size = newSize;
                }
        }

        //! change size and preserve contents
        void resize(size_type newSize)
        {
                m_ptr = m_alloc.reallocate(m_ptr, m_size, newSize, true);
                m_size = newSize;
        }

        //! swap contents and size with another SecBlock
        void swap(SecBlock<T, A> &b)
        {
                std::swap(m_alloc, b.m_alloc);
                std::swap(m_size, b.m_size);
                std::swap(m_ptr, b.m_ptr);
        }

//private:
        A m_alloc;
        size_type m_size;
        T *m_ptr;
};

typedef SecBlock<byte> SecByteBlock;
typedef SecBlock<byte, AllocatorWithCleanup<byte, true> > AlignedSecByteBlock;
typedef SecBlock<word> SecWordBlock;

//! a SecBlock with fixed size, allocated statically
template <class T, unsigned int S, class A = FixedSizeAllocatorWithCleanup<T, S> >
class FixedSizeSecBlock : public SecBlock<T, A>
{
public:
        explicit FixedSizeSecBlock() : SecBlock<T, A>(S) {}
};

template <class T, unsigned int S, bool T_Align16 = true>
class FixedSizeAlignedSecBlock : public FixedSizeSecBlock<T, S, FixedSizeAllocatorWithCleanup<T, S, NullAllocator<T>, T_Align16> >
{
};

//! a SecBlock that preallocates size S statically, and uses the heap when this size is exceeded
template <class T, unsigned int S, class A = FixedSizeAllocatorWithCleanup<T, S, AllocatorWithCleanup<T> > >
class SecBlockWithHint : public SecBlock<T, A>
{
public:
        explicit SecBlockWithHint(size_t size) : SecBlock<T, A>(size) {}
};

template<class T, bool A, class U, bool B>
inline bool operator==(const CryptoPP::AllocatorWithCleanup<T, A>&, const CryptoPP::AllocatorWithCleanup<U, B>&) {return (true);}
template<class T, bool A, class U, bool B>
inline bool operator!=(const CryptoPP::AllocatorWithCleanup<T, A>&, const CryptoPP::AllocatorWithCleanup<U, B>&) {return (false);}

NAMESPACE_END

NAMESPACE_BEGIN(std)
template <class T, class A>
inline void swap(CryptoPP::SecBlock<T, A> &a, CryptoPP::SecBlock<T, A> &b)
{
        a.swap(b);
}

#if defined(_STLP_DONT_SUPPORT_REBIND_MEMBER_TEMPLATE) || (defined(_STLPORT_VERSION) && !defined(_STLP_MEMBER_TEMPLATE_CLASSES))
// working for STLport 5.1.3 and MSVC 6 SP5
template <class _Tp1, class _Tp2>
inline CryptoPP::AllocatorWithCleanup<_Tp2>&
__stl_alloc_rebind(CryptoPP::AllocatorWithCleanup<_Tp1>& __a, const _Tp2*)
{
        return (CryptoPP::AllocatorWithCleanup<_Tp2>&)(__a);
}
#endif

NAMESPACE_END

#endif