NimBLERemoteValueAttribute.cpp

/*
 * Copyright 2020-2025 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.
 */

#include "NimBLERemoteValueAttribute.h"
#if CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_CENTRAL)

# include "NimBLEClient.h"
# include "NimBLEUtils.h"
# include "NimBLELog.h"

# include <climits>

static const char* LOG_TAG = "NimBLERemoteValueAttribute";

bool NimBLERemoteValueAttribute::writeValue(const uint8_t* data, size_t length, bool response) const {
    NIMBLE_LOGD(LOG_TAG, ">> writeValue()");

    const NimBLEClient*   pClient    = getClient();
    int                   retryCount = 1;
    int                   rc         = 0;
    uint16_t              mtu        = pClient->getMTU() - 3;
    NimBLEUtils::TaskData taskData(const_cast<NimBLERemoteValueAttribute*>(this));

    // Check if the data length is longer than we can write in one connection event.
    // If so we must do a long write which requires a response.
    if (length <= mtu && !response) {
        rc = ble_gattc_write_no_rsp_flat(pClient->getConnHandle(), getHandle(), data, length);
        goto Done;
    }

    do {
        if (length > mtu) {
            NIMBLE_LOGI(LOG_TAG, "writeValue: long write");
            os_mbuf* om = ble_hs_mbuf_from_flat(data, length);
            rc = ble_gattc_write_long(pClient->getConnHandle(), getHandle(), 0, om, NimBLERemoteValueAttribute::onWriteCB, &taskData);
        } else {
            rc = ble_gattc_write_flat(pClient->getConnHandle(),
                                      getHandle(),
                                      data,
                                      length,
                                      NimBLERemoteValueAttribute::onWriteCB,
                                      &taskData);
        }

        if (rc != 0) {
            goto Done;
        }

        NimBLEUtils::taskWait(taskData, BLE_NPL_TIME_FOREVER);
        rc = taskData.m_flags;
        switch (rc) {
            case 0:
            case BLE_HS_EDONE:
                rc = 0;
                break;
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_ATTR_NOT_LONG):
                NIMBLE_LOGE(LOG_TAG, "Long write not supported by peer; Truncating length to %d", mtu);
                retryCount++;
                length = mtu;
                break;

            case BLE_HS_ATT_ERR(BLE_ATT_ERR_INSUFFICIENT_AUTHEN):
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_INSUFFICIENT_AUTHOR):
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_INSUFFICIENT_ENC):
                if (retryCount && pClient->secureConnection()) break;
            /* Else falls through. */
            default:
                goto Done;
        }
    } while (rc != 0 && retryCount--);

Done:
    if (rc != 0) {
        NIMBLE_LOGE(LOG_TAG, "<< writeValue failed, rc: %d %s", rc, NimBLEUtils::returnCodeToString(rc));
    } else {
        NIMBLE_LOGD(LOG_TAG, "<< writeValue");
    }

    return (rc == 0);
} // writeValue

/**
 * @brief Callback for characteristic write operation.
 * @return success == 0 or error code.
 */
int NimBLERemoteValueAttribute::onWriteCB(uint16_t conn_handle, const ble_gatt_error* error, ble_gatt_attr* attr, void* arg) {
    auto       pTaskData = static_cast<NimBLEUtils::TaskData*>(arg);
    const auto pAtt      = static_cast<NimBLERemoteValueAttribute*>(pTaskData->m_pInstance);

    if (error->status == BLE_HS_ENOTCONN) {
        NIMBLE_LOGE(LOG_TAG, "<< Write complete; Not connected");
        NimBLEUtils::taskRelease(*pTaskData, error->status);
        return error->status;
    }

    if (pAtt->getClient()->getConnHandle() != conn_handle) {
        return 0;
    }

    NIMBLE_LOGI(LOG_TAG, "Write complete; status=%d", error->status);
    NimBLEUtils::taskRelease(*pTaskData, error->status);
    return 0;
}

/**
 * @brief Read the value of the remote characteristic.
 * @param [in] timestamp A pointer to a time_t struct to store the time the value was read.
 * @return The value of the remote characteristic.
 */
NimBLEAttValue NimBLERemoteValueAttribute::readValue(time_t* timestamp) {
    NIMBLE_LOGD(LOG_TAG, ">> readValue()");

    NimBLEAttValue        value{};
    const NimBLEClient*   pClient    = getClient();
    int                   rc         = 0;
    int                   retryCount = 1;
    NimBLEUtils::TaskData taskData(const_cast<NimBLERemoteValueAttribute*>(this), 0, &value);

    do {
        rc = ble_gattc_read_long(pClient->getConnHandle(), getHandle(), 0, NimBLERemoteValueAttribute::onReadCB, &taskData);
        if (rc != 0) {
            goto Done;
        }

        NimBLEUtils::taskWait(taskData, BLE_NPL_TIME_FOREVER);
        rc = taskData.m_flags;
        switch (rc) {
            case 0:
            case BLE_HS_EDONE:
                rc = 0;
                break;
            // Characteristic is not long-readable, return with what we have.
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_ATTR_NOT_LONG):
                NIMBLE_LOGI(LOG_TAG, "Attribute not long");
                rc = ble_gattc_read(pClient->getConnHandle(), getHandle(), NimBLERemoteValueAttribute::onReadCB, &taskData);
                if (rc != 0) {
                    goto Done;
                }
                retryCount++;
                break;
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_INSUFFICIENT_AUTHEN):
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_INSUFFICIENT_AUTHOR):
            case BLE_HS_ATT_ERR(BLE_ATT_ERR_INSUFFICIENT_ENC):
                if (retryCount && pClient->secureConnection()) break;
            /* Else falls through. */
            default:
                goto Done;
        }
    } while (rc != 0 && retryCount--);

    value.setTimeStamp();
    m_value = value;
    if (timestamp != nullptr) {
        *timestamp = value.getTimeStamp();
    }

Done:
    if (rc != 0) {
        NIMBLE_LOGE(LOG_TAG, "<< readValue failed rc=%d, %s", rc, NimBLEUtils::returnCodeToString(rc));
    } else {
        NIMBLE_LOGD(LOG_TAG, "<< readValue");
    }

    return value;
} // readValue

/**
 * @brief Callback for characteristic read operation.
 * @return success == 0 or error code.
 */
int NimBLERemoteValueAttribute::onReadCB(uint16_t conn_handle, const ble_gatt_error* error, ble_gatt_attr* attr, void* arg) {
    auto       pTaskData = static_cast<NimBLEUtils::TaskData*>(arg);
    const auto pAtt      = static_cast<NimBLERemoteValueAttribute*>(pTaskData->m_pInstance);

    if (error->status == BLE_HS_ENOTCONN) {
        NIMBLE_LOGE(LOG_TAG, "<< Read complete; Not connected");
        NimBLEUtils::taskRelease(*pTaskData, error->status);
        return error->status;
    }

    if (pAtt->getClient()->getConnHandle() != conn_handle) {
        return 0;
    }

    int rc = error->status;
    NIMBLE_LOGI(LOG_TAG, "Read complete; status=%d", rc);

    if (rc == 0) {
        if (attr) {
            auto     valBuf   = static_cast<NimBLEAttValue*>(pTaskData->m_pBuf);
            uint16_t data_len = OS_MBUF_PKTLEN(attr->om);
            if ((valBuf->size() + data_len) > BLE_ATT_ATTR_MAX_LEN) {
                rc = BLE_ATT_ERR_INVALID_ATTR_VALUE_LEN;
            } else {
                NIMBLE_LOGD(LOG_TAG, "Got %u bytes", data_len);
                valBuf->append(attr->om->om_data, data_len);
                return 0;
            }
        }
    }

    NimBLEUtils::taskRelease(*pTaskData, rc);
    return rc;
} // onReadCB

#endif // CONFIG_BT_NIMBLE_ENABLED && MYNEWT_VAL(BLE_ROLE_CENTRAL)