mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-12-21 05:53:09 +00:00
463 lines
11 KiB
C++
463 lines
11 KiB
C++
/*
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* Copyright (c)2019 ZeroTier, Inc.
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file in the project's root directory.
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*
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* Change Date: 2023-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2.0 of the Apache License.
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*/
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/****/
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#ifndef ZT_BUFFER_HPP
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#define ZT_BUFFER_HPP
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#include <string.h>
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#include <stdint.h>
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#include <stdexcept>
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#include <string>
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#include <algorithm>
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#include <utility>
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#include "Constants.hpp"
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#include "Utils.hpp"
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#if defined(__GNUC__) && (!defined(ZT_NO_TYPE_PUNNING))
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#define ZT_VAR_MAY_ALIAS __attribute__((__may_alias__))
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#else
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#define ZT_VAR_MAY_ALIAS
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#endif
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namespace ZeroTier {
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/**
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* A variable length but statically allocated buffer
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*
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* Bounds-checking is done everywhere, since this is used in security
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* critical code. This supports construction and assignment from buffers
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* of differing capacities, provided the data actually in them fits.
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* It throws std::out_of_range on any boundary violation.
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*
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* The at(), append(), etc. methods encode integers larger than 8-bit in
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* big-endian (network) byte order.
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*
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* @tparam C Total capacity
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*/
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template<unsigned int C>
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class Buffer
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{
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// I love me!
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template <unsigned int C2> friend class Buffer;
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public:
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// STL container idioms
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typedef unsigned char value_type;
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typedef unsigned char * pointer;
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typedef const char * const_pointer;
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typedef char & reference;
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typedef const char & const_reference;
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typedef char * iterator;
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typedef const char * const_iterator;
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typedef unsigned int size_type;
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typedef int difference_type;
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typedef std::reverse_iterator<iterator> reverse_iterator;
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typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
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inline iterator begin() { return _b; }
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inline iterator end() { return (_b + _l); }
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inline const_iterator begin() const { return _b; }
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inline const_iterator end() const { return (_b + _l); }
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inline reverse_iterator rbegin() { return reverse_iterator(begin()); }
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inline reverse_iterator rend() { return reverse_iterator(end()); }
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inline const_reverse_iterator rbegin() const { return const_reverse_iterator(begin()); }
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inline const_reverse_iterator rend() const { return const_reverse_iterator(end()); }
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Buffer() :
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_l(0)
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{
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}
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Buffer(unsigned int l)
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{
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if (l > C)
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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_l = l;
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}
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template<unsigned int C2>
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Buffer(const Buffer<C2> &b)
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{
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*this = b;
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}
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Buffer(const void *b,unsigned int l)
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{
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copyFrom(b,l);
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}
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template<unsigned int C2>
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inline Buffer &operator=(const Buffer<C2> &b)
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{
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if (unlikely(b._l > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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if (C2 == C) {
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memcpy(this,&b,sizeof(Buffer<C>));
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} else {
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memcpy(_b,b._b,_l = b._l);
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}
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return *this;
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}
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inline void copyFrom(const void *b,unsigned int l)
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{
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if (unlikely(l > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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memcpy(_b,b,l);
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_l = l;
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}
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unsigned char operator[](const unsigned int i) const
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{
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if (unlikely(i >= _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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return (unsigned char)_b[i];
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}
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unsigned char &operator[](const unsigned int i)
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{
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if (unlikely(i >= _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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return ((unsigned char *)_b)[i];
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}
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/**
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* Get a raw pointer to a field with bounds checking
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*
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* This isn't perfectly safe in that the caller could still overflow
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* the pointer, but its use provides both a sanity check and
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* documentation / reminder to the calling code to treat the returned
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* pointer as being of size [l].
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*
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* @param i Index of field in buffer
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* @param l Length of field in bytes
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* @return Pointer to field data
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* @throws std::out_of_range Field extends beyond data size
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*/
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unsigned char *field(unsigned int i,unsigned int l)
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{
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if (unlikely((i + l) > _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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return (unsigned char *)(_b + i);
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}
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const unsigned char *field(unsigned int i,unsigned int l) const
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{
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if (unlikely((i + l) > _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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return (const unsigned char *)(_b + i);
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}
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/**
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* Place a primitive integer value at a given position
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*
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* @param i Index to place value
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* @param v Value
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* @tparam T Integer type (e.g. uint16_t, int64_t)
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*/
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template<typename T>
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inline void setAt(unsigned int i,const T v)
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{
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if (unlikely((i + sizeof(T)) > _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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#ifdef ZT_NO_TYPE_PUNNING
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uint8_t *p = reinterpret_cast<uint8_t *>(_b + i);
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for(unsigned int x=1;x<=sizeof(T);++x)
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*(p++) = (uint8_t)(v >> (8 * (sizeof(T) - x)));
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#else
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T *const ZT_VAR_MAY_ALIAS p = reinterpret_cast<T *>(_b + i);
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*p = Utils::hton(v);
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#endif
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}
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/**
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* Get a primitive integer value at a given position
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*
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* @param i Index to get integer
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* @tparam T Integer type (e.g. uint16_t, int64_t)
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* @return Integer value
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*/
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template<typename T>
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inline T at(unsigned int i) const
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{
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if (unlikely((i + sizeof(T)) > _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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#ifdef ZT_NO_TYPE_PUNNING
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T v = 0;
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const uint8_t *p = reinterpret_cast<const uint8_t *>(_b + i);
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for(unsigned int x=0;x<sizeof(T);++x) {
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v <<= 8;
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v |= (T)*(p++);
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}
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return v;
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#else
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const T *const ZT_VAR_MAY_ALIAS p = reinterpret_cast<const T *>(_b + i);
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return Utils::ntoh(*p);
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#endif
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}
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/**
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* Append an integer type to this buffer
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*
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* @param v Value to append
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* @tparam T Integer type (e.g. uint16_t, int64_t)
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* @throws std::out_of_range Attempt to append beyond capacity
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*/
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template<typename T>
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inline void append(const T v)
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{
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if (unlikely((_l + sizeof(T)) > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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#ifdef ZT_NO_TYPE_PUNNING
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uint8_t *p = reinterpret_cast<uint8_t *>(_b + _l);
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for(unsigned int x=1;x<=sizeof(T);++x)
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*(p++) = (uint8_t)(v >> (8 * (sizeof(T) - x)));
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#else
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T *const ZT_VAR_MAY_ALIAS p = reinterpret_cast<T *>(_b + _l);
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*p = Utils::hton(v);
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#endif
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_l += sizeof(T);
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}
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/**
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* Append a run of bytes
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*
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* @param c Character value to append
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* @param n Number of times to append
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* @throws std::out_of_range Attempt to append beyond capacity
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*/
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inline void append(unsigned char c,unsigned int n)
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{
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if (unlikely((_l + n) > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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for(unsigned int i=0;i<n;++i)
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_b[_l++] = (char)c;
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}
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/**
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* Append secure random bytes
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*
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* @param n Number of random bytes to append
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*/
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inline void appendRandom(unsigned int n)
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{
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if (unlikely((_l + n) > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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Utils::getSecureRandom(_b + _l,n);
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_l += n;
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}
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/**
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* Append a C-array of bytes
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*
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* @param b Data
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* @param l Length
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* @throws std::out_of_range Attempt to append beyond capacity
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*/
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inline void append(const void *b,unsigned int l)
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{
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if (unlikely((_l + l) > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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memcpy(_b + _l,b,l);
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_l += l;
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}
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/**
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* Append a C string including null termination byte
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*
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* @param s C string
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* @throws std::out_of_range Attempt to append beyond capacity
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*/
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inline void appendCString(const char *s)
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{
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for(;;) {
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if (unlikely(_l >= C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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if (!(_b[_l++] = *(s++)))
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break;
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}
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}
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/**
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* Append a buffer
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*
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* @param b Buffer to append
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* @tparam C2 Capacity of second buffer (typically inferred)
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* @throws std::out_of_range Attempt to append beyond capacity
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*/
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template<unsigned int C2>
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inline void append(const Buffer<C2> &b)
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{
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append(b._b,b._l);
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}
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/**
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* Increment size and return pointer to field of specified size
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*
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* Nothing is actually written to the memory. This is a shortcut
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* for addSize() followed by field() to reference the previous
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* position and the new size.
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*
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* @param l Length of field to append
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* @return Pointer to beginning of appended field of length 'l'
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*/
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inline char *appendField(unsigned int l)
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{
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if (unlikely((_l + l) > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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char *r = _b + _l;
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_l += l;
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return r;
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}
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/**
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* Increment size by a given number of bytes
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*
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* The contents of new space are undefined.
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*
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* @param i Bytes to increment
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* @throws std::out_of_range Capacity exceeded
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*/
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inline void addSize(unsigned int i)
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{
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if (unlikely((i + _l) > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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_l += i;
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}
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/**
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* Set size of data in buffer
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*
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* The contents of new space are undefined.
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*
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* @param i New size
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* @throws std::out_of_range Size larger than capacity
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*/
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inline void setSize(const unsigned int i)
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{
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if (unlikely(i > C))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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_l = i;
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}
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/**
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* Move everything after 'at' to the buffer's front and truncate
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*
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* @param at Truncate before this position
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* @throws std::out_of_range Position is beyond size of buffer
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*/
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inline void behead(const unsigned int at)
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{
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if (!at)
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return;
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if (unlikely(at > _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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::memmove(_b,_b + at,_l -= at);
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}
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/**
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* Erase something from the middle of the buffer
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*
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* @param start Starting position
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* @param length Length of block to erase
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* @throws std::out_of_range Position plus length is beyond size of buffer
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*/
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inline void erase(const unsigned int at,const unsigned int length)
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{
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const unsigned int endr = at + length;
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if (unlikely(endr > _l))
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throw ZT_EXCEPTION_OUT_OF_BOUNDS;
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::memmove(_b + at,_b + endr,_l - endr);
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_l -= length;
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}
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/**
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* Set buffer data length to zero
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*/
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inline void clear() { _l = 0; }
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/**
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* Zero buffer up to size()
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*/
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inline void zero() { memset(_b,0,_l); }
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/**
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* Zero unused capacity area
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*/
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inline void zeroUnused() { memset(_b + _l,0,C - _l); }
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/**
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* Unconditionally and securely zero buffer's underlying memory
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*/
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inline void burn() { Utils::burn(_b,sizeof(_b)); }
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/**
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* @return Constant pointer to data in buffer
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*/
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inline const void *data() const { return _b; }
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/**
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* @return Non-constant pointer to data in buffer
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*/
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inline void *unsafeData() { return _b; }
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/**
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* @return Size of data in buffer
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*/
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inline unsigned int size() const { return _l; }
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/**
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* @return Capacity of buffer
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*/
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inline unsigned int capacity() const { return C; }
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template<unsigned int C2>
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inline bool operator==(const Buffer<C2> &b) const
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{
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return ((_l == b._l)&&(!memcmp(_b,b._b,_l)));
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}
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template<unsigned int C2>
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inline bool operator!=(const Buffer<C2> &b) const
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{
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return ((_l != b._l)||(memcmp(_b,b._b,_l)));
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}
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template<unsigned int C2>
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inline bool operator<(const Buffer<C2> &b) const
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{
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return (memcmp(_b,b._b,std::min(_l,b._l)) < 0);
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}
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template<unsigned int C2>
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inline bool operator>(const Buffer<C2> &b) const
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{
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return (b < *this);
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}
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template<unsigned int C2>
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inline bool operator<=(const Buffer<C2> &b) const
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{
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return !(b < *this);
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}
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template<unsigned int C2>
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inline bool operator>=(const Buffer<C2> &b) const
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{
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return !(*this < b);
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}
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private:
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char ZT_VAR_MAY_ALIAS _b[C];
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unsigned int _l;
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};
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} // namespace ZeroTier
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#endif
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