NimBLEAttValue.h

/*
 * Copyright 2020-2026 Ryan Powell <ryan@nable-embedded.io> and
 * esp-nimble-cpp, NimBLE-Arduino contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef NIMBLE_CPP_ATTVALUE_H
#define NIMBLE_CPP_ATTVALUE_H
 
#include "nimconfig.h"
#if CONFIG_BT_ENABLED
 
/* Enables the use of Arduino String class for attribute values */
# ifndef NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
#  define NIMBLE_CPP_ARDUINO_STRING_AVAILABLE (__has_include(<Arduino.h>))
# endif
 
# if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
#  include <WString.h>
# endif
 
# 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 {};
 
/* Used to determine if the type passed to a template has a value_type member (std::vector, std::array, std::string, etc.). */
template <typename T, typename = void>
struct Has_value_type : std::false_type {};
 
template <typename T>
struct Has_value_type<T, decltype(void(sizeof(typename T::value_type)))>
    : std::true_type {};
 
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:
    NimBLEAttValue(uint16_t init_len = CONFIG_NIMBLE_CPP_ATT_VALUE_INIT_LENGTH, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN);
 
    NimBLEAttValue(const uint8_t* value, uint16_t len, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN);
 
    NimBLEAttValue(const char* value, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
        : NimBLEAttValue((uint8_t*)value, (uint16_t)strlen(value), max_len) {}
 
    NimBLEAttValue(std::initializer_list<uint8_t> list, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
        : NimBLEAttValue(list.begin(), list.size(), max_len) {}
 
    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) {}
 
    NimBLEAttValue(const std::vector<uint8_t> vec, uint16_t max_len = BLE_ATT_ATTR_MAX_LEN)
        : NimBLEAttValue(&vec[0], vec.size(), max_len) {}
 
# if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
    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
 
    NimBLEAttValue(const NimBLEAttValue& source) { deepCopy(source); }
 
    NimBLEAttValue(NimBLEAttValue&& source) { *this = std::move(source); }
 
    ~NimBLEAttValue();
 
    uint16_t max_size() const { return m_attr_max_len; }
 
    uint16_t capacity() const { return m_capacity; }
 
    uint16_t length() const { return m_attr_len; }
 
    uint16_t size() const { return m_attr_len; }
 
    const uint8_t* data() const { return m_attr_value; }
 
    const char* c_str() const { return reinterpret_cast<const char*>(m_attr_value); }
 
    const uint8_t* begin() const { return m_attr_value; }
 
    const uint8_t* end() const { return m_attr_value + m_attr_len; }
 
# if CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
    time_t getTimeStamp() const { return m_timestamp; }
 
    void setTimeStamp() { m_timestamp = time(nullptr); }
 
    void setTimeStamp(time_t t) { m_timestamp = t; }
# else
    time_t getTimeStamp() const { return 0; }
    void   setTimeStamp() {}
    void   setTimeStamp(time_t t) {}
# endif
 
    bool setValue(const uint8_t* value, uint16_t len);
 
    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;
    }
 
    NimBLEAttValue& append(const uint8_t* value, uint16_t len);
 
    /*********************** Template Functions ************************/
 
# if __cplusplus < 201703L
    template <typename T>
#  ifdef _DOXYGEN_
    bool
#  else
    typename std::enable_if<std::is_array<T>::value &&
                                std::is_same<typename std::remove_extent<T>::type, char>::value,
                            bool>::type
#  endif
    setValue(const T& s) {
        return setValue(reinterpret_cast<const uint8_t*>(s), strnlen(s, sizeof(T)));
    }
 
    template <typename T>
#  ifdef _DOXYGEN_
    bool
#  else
    typename std::enable_if<!std::is_pointer<T>::value && !Has_c_str_length<T>::value && !Has_data_size<T>::value &&
                                !(std::is_array<T>::value &&
                                  std::is_same<typename std::remove_extent<T>::type, char>::value),
                            bool>::type
#  endif
    setValue(const T& v) {
        return setValue(reinterpret_cast<const uint8_t*>(&v), sizeof(T));
    }
 
    template <typename T>
#  ifdef _DOXYGEN_
    bool
#  else
    typename std::enable_if<Has_c_str_length<T>::value && !Has_data_size<T>::value, bool>::type
#  endif
    setValue(const T& s) {
        return setValue(reinterpret_cast<const uint8_t*>(s.c_str()), s.length());
    }
 
    template <typename T>
#  ifdef _DOXYGEN_
    bool
#  else
    typename std::enable_if<Has_data_size<T>::value && Has_value_type<T>::value, bool>::type
#  endif
    setValue(const T& v) {
        return setValue(
            reinterpret_cast<const uint8_t*>(v.data()),
            v.size() * sizeof(typename T::value_type)
        );
    }
 
    template <typename T>
#  ifdef _DOXYGEN_
    bool
#  else
    typename std::enable_if<Has_data_size<T>::value && !Has_value_type<T>::value, bool>::type
#  endif
    setValue(const T& v) {
        return setValue(reinterpret_cast<const uint8_t*>(v.data()), v.size());
    }
 
# else
    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) {
            if constexpr (Has_value_type<T>::value) {
                return setValue(reinterpret_cast<const uint8_t*>(s.data()), s.size() * sizeof(typename T::value_type));
            } else {
                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 if constexpr (std::is_array<T>::value &&
                             std::is_same<typename std::remove_extent<T>::type, char>::value) {
            return setValue(reinterpret_cast<const uint8_t*>(s), strnlen(s, sizeof(s)));
        } else {
            return setValue(reinterpret_cast<const uint8_t*>(&s), sizeof(s));
        }
    }
# endif
 
    template <typename T>
    T getValue(time_t* timestamp = nullptr, bool skipSizeCheck = false) const {
        if (timestamp != nullptr) {
# if CONFIG_NIMBLE_CPP_ATT_VALUE_TIMESTAMP_ENABLED
            *timestamp = m_timestamp;
# else
            *timestamp = 0;
# endif
        }
 
        if (!skipSizeCheck && size() < sizeof(T)) {
            return T();
        }
        return *(reinterpret_cast<const T*>(m_attr_value));
    }
 
    /*********************** Operators ************************/
 
    uint8_t operator[](int pos) const;
 
    operator std::vector<uint8_t>() const { return std::vector<uint8_t>(m_attr_value, m_attr_value + m_attr_len); }
 
    operator std::string() const { return std::string(reinterpret_cast<char*>(m_attr_value), m_attr_len); }
 
    operator const uint8_t*() const { return m_attr_value; }
 
    NimBLEAttValue& operator+=(const NimBLEAttValue& source) { return append(source.data(), source.size()); }
 
    NimBLEAttValue& operator=(const std::string& source) {
        setValue(reinterpret_cast<const uint8_t*>(&source[0]), source.size());
        return *this;
    }
 
    NimBLEAttValue& operator=(NimBLEAttValue&& source);
 
    NimBLEAttValue& operator=(const NimBLEAttValue& source);
 
    bool operator==(const NimBLEAttValue& source) const {
        return (m_attr_len == source.size()) ? memcmp(m_attr_value, source.data(), m_attr_len) == 0 : false;
    }
 
    bool operator!=(const NimBLEAttValue& source) const { return !(*this == source); }
 
# if NIMBLE_CPP_ARDUINO_STRING_AVAILABLE
    operator String() const { return String(reinterpret_cast<char*>(m_attr_value)); }
# endif
};
 
#endif // CONFIG_BT_ENABLED
#endif // NIMBLE_CPP_ATTVALUE_H_