esp-nimble-cpp/src/NimBLEAttValue.h
William Emfinger 3820f57076
fix: #200 Enable use of data()/size() before trying c_str()/length() (#201)
* fix: #200 Use `data()`/`size()` instead of `c_str()`/`length()`

* Reduce duplication, only allow template function in characteristic and remote value attr if the type is not a pointer (otherwise sizeof is useless). add appropriate notes

* clean up AttValue::setValue to remove unnecessary length parameter enabling requirement of non-pointer type
2024-10-14 17:02:21 -06:00

314 lines
12 KiB
C++

/*
* NimBLEAttValue.h
*
* Created: on March 18, 2021
* Author H2zero
*
*/
#ifndef NIMBLE_CPP_ATTVALUE_H
#define NIMBLE_CPP_ATTVALUE_H
#include "nimconfig.h"
#if defined(CONFIG_BT_ENABLED)
# ifdef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
# include <Arduino.h>
# endif
# include "NimBLELog.h"
# include <string>
# include <vector>
# include <ctime>
# include <cstring>
# include <cstdint>
# ifndef CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
# define CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED 0
# endif
# ifndef BLE_ATT_ATTR_MAX_LEN
# define BLE_ATT_ATTR_MAX_LEN 512
# endif
# if !defined(CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH)
# define CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH 20
# elif CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH > BLE_ATT_ATTR_MAX_LEN
# error CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH cannot be larger than 512 (BLE_ATT_ATTR_MAX_LEN)
# elif CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH < 1
# error CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH cannot be less than 1; Range = 1 : 512
# endif
/* Used to determine if the type passed to a template has a data() and size() method. */
template <typename T, typename = void, typename = void>
struct Has_data_size : std::false_type {};
template <typename T>
struct Has_data_size<T, decltype(void(std::declval<T&>().data())), decltype(void(std::declval<T&>().size()))>
: std::true_type {};
/* Used to determine if the type passed to a template has a c_str() and length() method. */
template <typename T, typename = void, typename = void>
struct Has_c_str_length : std::false_type {};
template <typename T>
struct Has_c_str_length<T, decltype(void(std::declval<T&>().c_str())), decltype(void(std::declval<T&>().length()))>
: std::true_type {};
/**
* @brief A specialized container class to hold BLE attribute values.
* @details This class is designed to be more memory efficient than using\n
* standard container types for value storage, while being convertible to\n
* many different container classes.
*/
class NimBLEAttValue {
uint8_t* m_attr_value{};
uint16_t m_attr_max_len{};
uint16_t m_attr_len{};
uint16_t m_capacity{};
# if CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
time_t m_timestamp{};
# endif
void deepCopy(const NimBLEAttValue& source);
public:
/**
* @brief Default constructor.
* @param[in] init_len The initial size in bytes.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(uint16_t init_len = CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN);
/**
* @brief Construct with an initial value from a buffer.
* @param value A pointer to the initial value to set.
* @param[in] len The size in bytes of the value to set.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(const uint8_t *value, uint16_t len,
uint16_t max_len = BLE_ATT_ATTR_MAX_LEN);
/**
* @brief Construct with an initial value from a const char string.
* @param value A pointer to the initial value to set.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(const char *value, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
:NimBLEAttValue((uint8_t*)value, (uint16_t)strlen(value), max_len){}
/**
* @brief Construct with an initializer list.
* @param list An initializer list containing the initial value to set.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(std::initializer_list<uint8_t> list, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
: NimBLEAttValue(list.begin(), list.size(), max_len) {}
/**
* @brief Construct with an initial value from a std::string.
* @param str A std::string containing to the initial value to set.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(const std::string str, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
: NimBLEAttValue(reinterpret_cast<const uint8_t*>(&str[0]), str.length(), max_len) {}
/**
* @brief Construct with an initial value from a std::vector<uint8_t>.
* @param vec A std::vector<uint8_t> containing to the initial value to set.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(const std::vector<uint8_t> vec, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
: NimBLEAttValue(&vec[0], vec.size(), max_len) {}
# ifdef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
/**
* @brief Construct with an initial value from an Arduino String.
* @param str An Arduino String containing to the initial value to set.
* @param[in] max_len The max size in bytes that the value can be.
*/
NimBLEAttValue(const String str, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
: NimBLEAttValue(reinterpret_cast<const uint8_t*>(str.c_str()), str.length(), max_len) {}
# endif
/** @brief Copy constructor */
NimBLEAttValue(const NimBLEAttValue& source) { deepCopy(source); }
/** @brief Move constructor */
NimBLEAttValue(NimBLEAttValue&& source) { *this = std::move(source); }
/** @brief Destructor */
~NimBLEAttValue();
/** @brief Returns the max size in bytes */
uint16_t max_size() const { return m_attr_max_len; }
/** @brief Returns the currently allocated capacity in bytes */
uint16_t capacity() const { return m_capacity; }
/** @brief Returns the current length of the value in bytes */
uint16_t length() const { return m_attr_len; }
/** @brief Returns the current size of the value in bytes */
uint16_t size() const { return m_attr_len; }
/** @brief Returns a pointer to the internal buffer of the value */
const uint8_t* data() const { return m_attr_value; }
/** @brief Returns a pointer to the internal buffer of the value as a const char* */
const char* c_str() const { return reinterpret_cast<const char*>(m_attr_value); }
/** @brief Iterator begin */
const uint8_t* begin() const { return m_attr_value; }
/** @brief Iterator end */
const uint8_t* end() const { return m_attr_value + m_attr_len; }
# if CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
/** @brief Returns a timestamp of when the value was last updated */
time_t getTimeStamp() const { return m_timestamp; }
/** @brief Set the timestamp to the current time */
void setTimeStamp() { m_timestamp = time(nullptr); }
/**
* @brief Set the timestamp to the specified time
* @param[in] t The timestamp value to set
*/
void setTimeStamp(time_t t) { m_timestamp = t; }
# else
time_t getTimeStamp() const { return 0; }
void setTimeStamp() {}
void setTimeStamp(time_t t) {}
# endif
/**
* @brief Set the value from a buffer
* @param[in] value A pointer to a buffer containing the value.
* @param[in] len The length of the value in bytes.
* @returns True if successful.
*/
bool setValue(const uint8_t* value, uint16_t len);
/**
* @brief Set value to the value of const char*.
* @param [in] s A pointer to a const char value to set.
* @param [in] len The length of the value in bytes, defaults to strlen(s).
*/
bool setValue(const char* s, uint16_t len = 0) {
if (len == 0) {
len = strlen(s);
}
return setValue(reinterpret_cast<const uint8_t*>(s), len);
}
const NimBLEAttValue& getValue(time_t* timestamp = nullptr) const {
if (timestamp != nullptr) {
# if CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
*timestamp = m_timestamp;
# else
*timestamp = 0;
# endif
}
return *this;
}
/**
* @brief Append data to the value.
* @param[in] value A ponter to a data buffer with the value to append.
* @param[in] len The length of the value to append in bytes.
* @returns A reference to the appended NimBLEAttValue.
*/
NimBLEAttValue& append(const uint8_t* value, uint16_t len);
/*********************** Template Functions ************************/
/**
* @brief Template to set value to the value of <type\>val.
* @param [in] s The <type\>value to set.
* @note This function is only availabe if the type T is not a pointer.
*/
template <typename T>
typename std::enable_if<!std::is_pointer<T>::value, bool>::type
setValue(const T& s) {
if constexpr (Has_data_size<T>::value) {
return setValue(reinterpret_cast<const uint8_t*>(s.data()), s.size());
} else if constexpr (Has_c_str_length<T>::value) {
return setValue(reinterpret_cast<const uint8_t*>(s.c_str()), s.length());
} else {
return setValue(reinterpret_cast<const uint8_t*>(&s), sizeof(s));
}
}
/**
* @brief Template to return the value as a <type\>.
* @tparam T The type to convert the data to.
* @param [in] timestamp A pointer to a time_t struct to store the time the value was read.
* @param [in] skipSizeCheck If true it will skip checking if the data size is less than\n
* <tt>sizeof(<type\>)</tt>.
* @return The data converted to <type\> or NULL if skipSizeCheck is false and the data is\n
* less than <tt>sizeof(<type\>)</tt>.
* @details <b>Use:</b> <tt>getValue<type>(&timestamp, skipSizeCheck);</tt>
*/
template <typename T>
T getValue(time_t* timestamp = nullptr, bool skipSizeCheck = false) const {
if (!skipSizeCheck && size() < sizeof(T)) {
return T();
}
if (timestamp != nullptr) {
# if CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
*timestamp = m_timestamp;
# else
*timestamp = 0;
# endif
}
return *(reinterpret_cast<const T*>(m_attr_value));
}
/*********************** Operators ************************/
/** @brief Subscript operator */
uint8_t operator[](int pos) const {
NIMBLE_CPP_DEBUG_ASSERT(pos < m_attr_len);
return m_attr_value[pos];
}
/** @brief Operator; Get the value as a std::vector<uint8_t>. */
operator std::vector<uint8_t>() const { return std::vector<uint8_t>(m_attr_value, m_attr_value + m_attr_len); }
/** @brief Operator; Get the value as a std::string. */
operator std::string() const { return std::string(reinterpret_cast<char*>(m_attr_value), m_attr_len); }
/** @brief Operator; Get the value as a const uint8_t*. */
operator const uint8_t*() const { return m_attr_value; }
/** @brief Operator; Append another NimBLEAttValue. */
NimBLEAttValue& operator+=(const NimBLEAttValue& source) { return append(source.data(), source.size()); }
/** @brief Operator; Set the value from a std::string source. */
NimBLEAttValue& operator=(const std::string& source) {
setValue(reinterpret_cast<const uint8_t*>(&source[0]), source.size());
return *this;
}
/** @brief Move assignment operator */
NimBLEAttValue& operator=(NimBLEAttValue&& source);
/** @brief Copy assignment operator */
NimBLEAttValue& operator=(const NimBLEAttValue& source);
/** @brief Equality operator */
bool operator==(const NimBLEAttValue& source) const {
return (m_attr_len == source.size()) ? memcmp(m_attr_value, source.data(), m_attr_len) == 0 : false;
}
/** @brief Inequality operator */
bool operator!=(const NimBLEAttValue& source) const { return !(*this == source); }
# ifdef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
/** @brief Operator; Get the value as an Arduino String value. */
operator String() const { return String(reinterpret_cast<char*>(m_attr_value)); }
# endif
};
#endif /*(CONFIG_BT_ENABLED) */
#endif /* NIMBLE_CPP_ATTVALUE_H_ */