esp-idf/examples/bluetooth/nimble/blecent/main/main.c

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 "esp_log.h"
#include "nvs_flash.h"
/* BLE */
#include "nimble/nimble_port.h"
#include "nimble/nimble_port_freertos.h"
#include "host/ble_hs.h"
#include "host/util/util.h"
#include "console/console.h"
#include "services/gap/ble_svc_gap.h"
#include "blecent.h"

/*** The UUID of the service containing the subscribable characterstic ***/
static const ble_uuid_t * remote_svc_uuid =
    BLE_UUID128_DECLARE(0x2d, 0x71, 0xa2, 0x59, 0xb4, 0x58, 0xc8, 0x12,
                     	0x99, 0x99, 0x43, 0x95, 0x12, 0x2f, 0x46, 0x59);

/*** The UUID of the subscribable chatacteristic ***/
static const ble_uuid_t * remote_chr_uuid =
    BLE_UUID128_DECLARE(0x00, 0x00, 0x00, 0x00, 0x11, 0x11, 0x11, 0x11,
                     	0x22, 0x22, 0x22, 0x22, 0x33, 0x33, 0x33, 0x33);

static const char *tag = "NimBLE_BLE_CENT";
static int blecent_gap_event(struct ble_gap_event *event, void *arg);
static uint8_t peer_addr[6];

void ble_store_config_init(void);

#if MYNEWT_VAL(BLE_POWER_CONTROL)
static struct ble_gap_event_listener power_control_event_listener;
#endif

/**
 * Application Callback. Called when the custom subscribable chatacteristic
 * in the remote GATT server is read.
 * Expect to get the recently written data.
 **/
static int
blecent_on_custom_read(uint16_t conn_handle,
                       const struct ble_gatt_error *error,
                       struct ble_gatt_attr *attr,
                       void *arg)
{
    MODLOG_DFLT(INFO,
                "Read complete for the subscribable characteristic; "
                "status=%d conn_handle=%d", error->status, conn_handle);
    if (error->status == 0) {
        MODLOG_DFLT(INFO, " attr_handle=%d value=", attr->handle);
        print_mbuf(attr->om);
    }
    MODLOG_DFLT(INFO, "\n");

    return 0;
}

/**
 * Application Callback. Called when the custom subscribable characteristic
 * in the remote GATT server is written to.
 * Client has previously subscribed to this characeteristic,
 * so expect a notification from the server.
 **/
static int
blecent_on_custom_write(uint16_t conn_handle,
                        const struct ble_gatt_error *error,
                        struct ble_gatt_attr *attr,
                        void *arg)
{
    const struct peer_chr *chr;
    const struct peer *peer;
    int rc;

    MODLOG_DFLT(INFO,
                "Write to the custom subscribable characteristic complete; "
                "status=%d conn_handle=%d attr_handle=%d\n",
                error->status, conn_handle, attr->handle);

    peer = peer_find(conn_handle);
    chr = peer_chr_find_uuid(peer,
                             remote_svc_uuid,
                             remote_chr_uuid);
    if (chr == NULL) {
        MODLOG_DFLT(ERROR,
                    "Error: Peer doesn't have the custom subscribable characteristic\n");
        goto err;
    }

    /*** Performs a read on the characteristic, the result is handled in blecent_on_new_read callback ***/
    rc = ble_gattc_read(conn_handle, chr->chr.val_handle,
                        blecent_on_custom_read, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR,
                    "Error: Failed to read the custom subscribable characteristic; "
                    "rc=%d\n", rc);
        goto err;
    }

    return 0;
err:
    /* Terminate the connection */
    return ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
}

/**
 * Application Callback. Called when the custom subscribable characteristic
 * is subscribed to.
 **/
static int
blecent_on_custom_subscribe(uint16_t conn_handle,
                            const struct ble_gatt_error *error,
                            struct ble_gatt_attr *attr,
                            void *arg)
{
    const struct peer_chr *chr;
    uint8_t value;
    int rc;
    const struct peer *peer;

    MODLOG_DFLT(INFO,
                "Subscribe to the custom subscribable characteristic complete; "
                "status=%d conn_handle=%d", error->status, conn_handle);

    if (error->status == 0) {
        MODLOG_DFLT(INFO, " attr_handle=%d value=", attr->handle);
        print_mbuf(attr->om);
    }
    MODLOG_DFLT(INFO, "\n");

    peer = peer_find(conn_handle);
    chr = peer_chr_find_uuid(peer,
                             remote_svc_uuid,
                             remote_chr_uuid);
    if (chr == NULL) {
        MODLOG_DFLT(ERROR, "Error: Peer doesn't have the subscribable characteristic\n");
        goto err;
    }

    /* Write 1 byte to the new characteristic to test if it notifies after subscribing */
    value = 0x19;
    rc = ble_gattc_write_flat(conn_handle, chr->chr.val_handle,
                              &value, sizeof(value), blecent_on_custom_write, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR,
                    "Error: Failed to write to the subscribable characteristic; "
                    "rc=%d\n", rc);
        goto err;
    }

    return 0;
err:
    /* Terminate the connection */
    return ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
}

/**
 * Performs 3 operations on the remote GATT server.
 * 1. Subscribes to a characteristic by writing 0x10 to it's CCCD.
 * 2. Writes to the characteristic and expect a notification from remote.
 * 3. Reads the characteristic and expect to get the recently written information.
 **/
static void
blecent_custom_gatt_operations(const struct peer* peer)
{
    const struct peer_dsc *dsc;
    int rc;
    uint8_t value[2];

    dsc = peer_dsc_find_uuid(peer,
                             remote_svc_uuid,
                             remote_chr_uuid,
                             BLE_UUID16_DECLARE(BLE_GATT_DSC_CLT_CFG_UUID16));
    if (dsc == NULL) {
        MODLOG_DFLT(ERROR, "Error: Peer lacks a CCCD for the subscribable characterstic\n");
        goto err;
    }

    /*** Write 0x00 and 0x01 (The subscription code) to the CCCD ***/
    value[0] = 1;
    value[1] = 0;
    rc = ble_gattc_write_flat(peer->conn_handle, dsc->dsc.handle,
                              value, sizeof(value), blecent_on_custom_subscribe, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR,
                    "Error: Failed to subscribe to the subscribable characteristic; "
                    "rc=%d\n", rc);
        goto err;
    }

    return;
err:
    /* Terminate the connection */
    ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
}

/**
 * Application callback.  Called when the attempt to subscribe to notifications
 * for the ANS Unread Alert Status characteristic has completed.
 */
static int
blecent_on_subscribe(uint16_t conn_handle,
                     const struct ble_gatt_error *error,
                     struct ble_gatt_attr *attr,
                     void *arg)
{
    struct peer *peer;

    MODLOG_DFLT(INFO, "Subscribe complete; status=%d conn_handle=%d "
                "attr_handle=%d\n",
                error->status, conn_handle, attr->handle);

    peer = peer_find(conn_handle);
    if (peer == NULL) {
        MODLOG_DFLT(ERROR, "Error in finding peer, aborting...");
        ble_gap_terminate(conn_handle, BLE_ERR_REM_USER_CONN_TERM);
    }
    /* Subscribe to, write to, and read the custom characteristic*/
    blecent_custom_gatt_operations(peer);

    return 0;
}

/**
 * Application callback.  Called when the write to the ANS Alert Notification
 * Control Point characteristic has completed.
 */
static int
blecent_on_write(uint16_t conn_handle,
                 const struct ble_gatt_error *error,
                 struct ble_gatt_attr *attr,
                 void *arg)
{
    MODLOG_DFLT(INFO,
                "Write complete; status=%d conn_handle=%d attr_handle=%d\n",
                error->status, conn_handle, attr->handle);

    /* Subscribe to notifications for the Unread Alert Status characteristic.
     * A central enables notifications by writing two bytes (1, 0) to the
     * characteristic's client-characteristic-configuration-descriptor (CCCD).
     */
    const struct peer_dsc *dsc;
    uint8_t value[2];
    int rc;
    const struct peer *peer = peer_find(conn_handle);

    dsc = peer_dsc_find_uuid(peer,
                             BLE_UUID16_DECLARE(BLECENT_SVC_ALERT_UUID),
                             BLE_UUID16_DECLARE(BLECENT_CHR_UNR_ALERT_STAT_UUID),
                             BLE_UUID16_DECLARE(BLE_GATT_DSC_CLT_CFG_UUID16));
    if (dsc == NULL) {
        MODLOG_DFLT(ERROR, "Error: Peer lacks a CCCD for the Unread Alert "
                    "Status characteristic\n");
        goto err;
    }

    value[0] = 1;
    value[1] = 0;
    rc = ble_gattc_write_flat(conn_handle, dsc->dsc.handle,
                              value, sizeof value, blecent_on_subscribe, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "Error: Failed to subscribe to characteristic; "
                    "rc=%d\n", rc);
        goto err;
    }

    return 0;
err:
    /* Terminate the connection. */
    return ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
}

/**
 * Application callback.  Called when the read of the ANS Supported New Alert
 * Category characteristic has completed.
 */
static int
blecent_on_read(uint16_t conn_handle,
                const struct ble_gatt_error *error,
                struct ble_gatt_attr *attr,
                void *arg)
{
    MODLOG_DFLT(INFO, "Read complete; status=%d conn_handle=%d", error->status,
                conn_handle);
    if (error->status == 0) {
        MODLOG_DFLT(INFO, " attr_handle=%d value=", attr->handle);
        print_mbuf(attr->om);
    }
    MODLOG_DFLT(INFO, "\n");

    /* Write two bytes (99, 100) to the alert-notification-control-point
     * characteristic.
     */
    const struct peer_chr *chr;
    uint8_t value[2];
    int rc;
    const struct peer *peer = peer_find(conn_handle);

    chr = peer_chr_find_uuid(peer,
                             BLE_UUID16_DECLARE(BLECENT_SVC_ALERT_UUID),
                             BLE_UUID16_DECLARE(BLECENT_CHR_ALERT_NOT_CTRL_PT));
    if (chr == NULL) {
        MODLOG_DFLT(ERROR, "Error: Peer doesn't support the Alert "
                    "Notification Control Point characteristic\n");
        goto err;
    }

    value[0] = 99;
    value[1] = 100;
    rc = ble_gattc_write_flat(conn_handle, chr->chr.val_handle,
                              value, sizeof value, blecent_on_write, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "Error: Failed to write characteristic; rc=%d\n",
                    rc);
        goto err;
    }

    return 0;
err:
    /* Terminate the connection. */
    return ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
}

/**
 * Performs three GATT operations against the specified peer:
 * 1. Reads the ANS Supported New Alert Category characteristic.
 * 2. After read is completed, writes the ANS Alert Notification Control Point characteristic.
 * 3. After write is completed, subscribes to notifications for the ANS Unread Alert Status
 *    characteristic.
 *
 * If the peer does not support a required service, characteristic, or
 * descriptor, then the peer lied when it claimed support for the alert
 * notification service!  When this happens, or if a GATT procedure fails,
 * this function immediately terminates the connection.
 */
static void
blecent_read_write_subscribe(const struct peer *peer)
{
    const struct peer_chr *chr;
    int rc;

    /* Read the supported-new-alert-category characteristic. */
    chr = peer_chr_find_uuid(peer,
                             BLE_UUID16_DECLARE(BLECENT_SVC_ALERT_UUID),
                             BLE_UUID16_DECLARE(BLECENT_CHR_SUP_NEW_ALERT_CAT_UUID));
    if (chr == NULL) {
        MODLOG_DFLT(ERROR, "Error: Peer doesn't support the Supported New "
                    "Alert Category characteristic\n");
        goto err;
    }

    rc = ble_gattc_read(peer->conn_handle, chr->chr.val_handle,
                        blecent_on_read, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "Error: Failed to read characteristic; rc=%d\n",
                    rc);
        goto err;
    }

    return;
err:
    /* Terminate the connection. */
    ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
}

/**
 * Called when service discovery of the specified peer has completed.
 */
static void
blecent_on_disc_complete(const struct peer *peer, int status, void *arg)
{

    if (status != 0) {
        /* Service discovery failed.  Terminate the connection. */
        MODLOG_DFLT(ERROR, "Error: Service discovery failed; status=%d "
                    "conn_handle=%d\n", status, peer->conn_handle);
        ble_gap_terminate(peer->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
        return;
    }

    /* Service discovery has completed successfully.  Now we have a complete
     * list of services, characteristics, and descriptors that the peer
     * supports.
     */
    MODLOG_DFLT(INFO, "Service discovery complete; status=%d "
                "conn_handle=%d\n", status, peer->conn_handle);

    /* Now perform three GATT procedures against the peer: read,
     * write, and subscribe to notifications for the ANS service.
     */
    blecent_read_write_subscribe(peer);
}

/**
 * Initiates the GAP general discovery procedure.
 */
static void
blecent_scan(void)
{
    uint8_t own_addr_type;
    struct ble_gap_disc_params disc_params;
    int rc;

    /* Figure out address to use while advertising (no privacy for now) */
    rc = ble_hs_id_infer_auto(0, &own_addr_type);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "error determining address type; rc=%d\n", rc);
        return;
    }

    /* Tell the controller to filter duplicates; we don't want to process
     * repeated advertisements from the same device.
     */
    disc_params.filter_duplicates = 1;

    /**
     * Perform a passive scan.  I.e., don't send follow-up scan requests to
     * each advertiser.
     */
    disc_params.passive = 1;

    /* Use defaults for the rest of the parameters. */
    disc_params.itvl = 0;
    disc_params.window = 0;
    disc_params.filter_policy = 0;
    disc_params.limited = 0;

    rc = ble_gap_disc(own_addr_type, BLE_HS_FOREVER, &disc_params,
                      blecent_gap_event, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "Error initiating GAP discovery procedure; rc=%d\n",
                    rc);
    }
}

/**
 * Indicates whether we should try to connect to the sender of the specified
 * advertisement.  The function returns a positive result if the device
 * advertises connectability and support for the Alert Notification service.
 */
#if CONFIG_EXAMPLE_EXTENDED_ADV
static int
ext_blecent_should_connect(const struct ble_gap_ext_disc_desc *disc)
{
    int offset = 0;
    int ad_struct_len = 0;

    if (disc->legacy_event_type != BLE_HCI_ADV_RPT_EVTYPE_ADV_IND &&
            disc->legacy_event_type != BLE_HCI_ADV_RPT_EVTYPE_DIR_IND) {
        return 0;
    }
    if (strlen(CONFIG_EXAMPLE_PEER_ADDR) && (strncmp(CONFIG_EXAMPLE_PEER_ADDR, "ADDR_ANY", strlen    ("ADDR_ANY")) != 0)) {
        ESP_LOGI(tag, "Peer address from menuconfig: %s", CONFIG_EXAMPLE_PEER_ADDR);
        /* Convert string to address */
        sscanf(CONFIG_EXAMPLE_PEER_ADDR, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
               &peer_addr[5], &peer_addr[4], &peer_addr[3],
               &peer_addr[2], &peer_addr[1], &peer_addr[0]);
        if (memcmp(peer_addr, disc->addr.val, sizeof(disc->addr.val)) != 0) {
            return 0;
        }
    }

    /* The device has to advertise support for the Alert Notification
    * service (0x1811).
    */
    do {
        ad_struct_len = disc->data[offset];

        if (!ad_struct_len) {
            break;
        }

	/* Search if ANS UUID is advertised */
        if (disc->data[offset] == 0x03 && disc->data[offset + 1] == 0x03) {
            if ( disc->data[offset + 2] == 0x18 && disc->data[offset + 3] == 0x11 ) {
                return 1;
            }
        }

        offset += ad_struct_len + 1;

     } while ( offset < disc->length_data );

    return 0;
}
#else
static int
blecent_should_connect(const struct ble_gap_disc_desc *disc)
{
    struct ble_hs_adv_fields fields;
    int rc;
    int i;

    /* The device has to be advertising connectability. */
    if (disc->event_type != BLE_HCI_ADV_RPT_EVTYPE_ADV_IND &&
            disc->event_type != BLE_HCI_ADV_RPT_EVTYPE_DIR_IND) {

        return 0;
    }

    rc = ble_hs_adv_parse_fields(&fields, disc->data, disc->length_data);
    if (rc != 0) {
        return rc;
    }

    if (strlen(CONFIG_EXAMPLE_PEER_ADDR) && (strncmp(CONFIG_EXAMPLE_PEER_ADDR, "ADDR_ANY", strlen("ADDR_ANY")) != 0)) {
        ESP_LOGI(tag, "Peer address from menuconfig: %s", CONFIG_EXAMPLE_PEER_ADDR);
        /* Convert string to address */
        sscanf(CONFIG_EXAMPLE_PEER_ADDR, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
               &peer_addr[5], &peer_addr[4], &peer_addr[3],
               &peer_addr[2], &peer_addr[1], &peer_addr[0]);
        if (memcmp(peer_addr, disc->addr.val, sizeof(disc->addr.val)) != 0) {
            return 0;
        }
    }

    /* The device has to advertise support for the Alert Notification
     * service (0x1811).
     */
    for (i = 0; i < fields.num_uuids16; i++) {
        if (ble_uuid_u16(&fields.uuids16[i].u) == BLECENT_SVC_ALERT_UUID) {
            return 1;
        }
    }

    return 0;
}
#endif

/**
 * Connects to the sender of the specified advertisement of it looks
 * interesting.  A device is "interesting" if it advertises connectability and
 * support for the Alert Notification service.
 */
static void
blecent_connect_if_interesting(void *disc)
{
    uint8_t own_addr_type;
    int rc;
    ble_addr_t *addr;

    /* Don't do anything if we don't care about this advertiser. */
#if CONFIG_EXAMPLE_EXTENDED_ADV
    if (!ext_blecent_should_connect((struct ble_gap_ext_disc_desc *)disc)) {
        return;
    }
#else
    if (!blecent_should_connect((struct ble_gap_disc_desc *)disc)) {
        return;
    }
#endif

    /* Scanning must be stopped before a connection can be initiated. */
    rc = ble_gap_disc_cancel();
    if (rc != 0) {
        MODLOG_DFLT(DEBUG, "Failed to cancel scan; rc=%d\n", rc);
        return;
    }

    /* Figure out address to use for connect (no privacy for now) */
    rc = ble_hs_id_infer_auto(0, &own_addr_type);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "error determining address type; rc=%d\n", rc);
        return;
    }

    /* Try to connect the the advertiser.  Allow 30 seconds (30000 ms) for
     * timeout.
     */
#if CONFIG_EXAMPLE_EXTENDED_ADV
    addr = &((struct ble_gap_ext_disc_desc *)disc)->addr;
#else
    addr = &((struct ble_gap_disc_desc *)disc)->addr;
#endif

    rc = ble_gap_connect(own_addr_type, addr, 30000, NULL,
                         blecent_gap_event, NULL);
    if (rc != 0) {
        MODLOG_DFLT(ERROR, "Error: Failed to connect to device; addr_type=%d "
                    "addr=%s; rc=%d\n",
                    addr->type, addr_str(addr->val), rc);
        return;
    }
}

#if MYNEWT_VAL(BLE_POWER_CONTROL)
static void blecent_power_control(uint16_t conn_handle)
{
    int rc;

    rc = ble_gap_read_remote_transmit_power_level(conn_handle, 0x01 );  // Attempting on LE 1M phy
    assert (rc == 0);

    rc = ble_gap_set_transmit_power_reporting_enable(conn_handle, 0x01, 0x01);
    assert (rc == 0);

    rc = ble_gap_set_path_loss_reporting_param(conn_handle, 60, 10, 30, 10, 2 ); //demo values
    assert (rc == 0);

    rc = ble_gap_set_path_loss_reporting_enable(conn_handle, 0x01);
    assert (rc == 0);
}

static int
blecent_gap_power_event(struct ble_gap_event *event, void *arg)
{

    switch(event->type) {
    case BLE_GAP_EVENT_TRANSMIT_POWER:
	MODLOG_DFLT(INFO, "Transmit power event : status=%d conn_handle=%d reason=%d "
                          "phy=%d power_level=%x power_level_flag=%d delta=%d",
		    event->transmit_power.status,
		    event->transmit_power.conn_handle,
		    event->transmit_power.reason,
		    event->transmit_power.phy,
		    event->transmit_power.transmit_power_level,
		    event->transmit_power.transmit_power_level_flag,
		    event->transmit_power.delta);
	return 0;

    case BLE_GAP_EVENT_PATHLOSS_THRESHOLD:
	MODLOG_DFLT(INFO, "Pathloss threshold event : conn_handle=%d current path loss=%d "
                          "zone_entered =%d",
		    event->pathloss_threshold.conn_handle,
		    event->pathloss_threshold.current_path_loss,
		    event->pathloss_threshold.zone_entered);
	return 0;

    default:
	return 0;
    }
}
#endif

/**
 * The nimble host executes this callback when a GAP event occurs.  The
 * application associates a GAP event callback with each connection that is
 * established.  blecent uses the same callback for all connections.
 *
 * @param event                 The event being signalled.
 * @param arg                   Application-specified argument; unused by
 *                                  blecent.
 *
 * @return                      0 if the application successfully handled the
 *                                  event; nonzero on failure.  The semantics
 *                                  of the return code is specific to the
 *                                  particular GAP event being signalled.
 */
static int
blecent_gap_event(struct ble_gap_event *event, void *arg)
{
    struct ble_gap_conn_desc desc;
    struct ble_hs_adv_fields fields;
    int rc;

    switch (event->type) {
    case BLE_GAP_EVENT_DISC:
        rc = ble_hs_adv_parse_fields(&fields, event->disc.data,
                                     event->disc.length_data);
        if (rc != 0) {
            return 0;
        }

        /* An advertisment report was received during GAP discovery. */
        print_adv_fields(&fields);

        /* Try to connect to the advertiser if it looks interesting. */
        blecent_connect_if_interesting(&event->disc);
        return 0;

    case BLE_GAP_EVENT_CONNECT:
        /* A new connection was established or a connection attempt failed. */
        if (event->connect.status == 0) {
            /* Connection successfully established. */
            MODLOG_DFLT(INFO, "Connection established ");

            rc = ble_gap_conn_find(event->connect.conn_handle, &desc);
            assert(rc == 0);
            print_conn_desc(&desc);
            MODLOG_DFLT(INFO, "\n");

            /* Remember peer. */
            rc = peer_add(event->connect.conn_handle);
            if (rc != 0) {
                MODLOG_DFLT(ERROR, "Failed to add peer; rc=%d\n", rc);
                return 0;
            }

#if MYNEWT_VAL(BLE_POWER_CONTROL)
            blecent_power_control(event->connect.conn_handle);

            ble_gap_event_listener_register(&power_control_event_listener,
                                       blecent_gap_power_event, NULL);
#endif

#if CONFIG_EXAMPLE_ENCRYPTION
            /** Initiate security - It will perform
             * Pairing (Exchange keys)
             * Bonding (Store keys)
             * Encryption (Enable encryption)
             * Will invoke event BLE_GAP_EVENT_ENC_CHANGE
             **/
            rc = ble_gap_security_initiate(event->connect.conn_handle);
            if (rc != 0) {
                MODLOG_DFLT(INFO, "Security could not be initiated, rc = %d\n", rc);
                return ble_gap_terminate(event->connect.conn_handle,
                                         BLE_ERR_REM_USER_CONN_TERM);
            } else {
                MODLOG_DFLT(INFO, "Connection secured\n");
            }
#else
            /* Perform service discovery */
            rc = peer_disc_all(event->connect.conn_handle,
                        blecent_on_disc_complete, NULL);
            if(rc != 0) {
                MODLOG_DFLT(ERROR, "Failed to discover services; rc=%d\n", rc);
                return 0;
            }
#endif
        } else {
            /* Connection attempt failed; resume scanning. */
            MODLOG_DFLT(ERROR, "Error: Connection failed; status=%d\n",
                        event->connect.status);
            blecent_scan();
        }

        return 0;

    case BLE_GAP_EVENT_DISCONNECT:
        /* Connection terminated. */
        MODLOG_DFLT(INFO, "disconnect; reason=%d ", event->disconnect.reason);
        print_conn_desc(&event->disconnect.conn);
        MODLOG_DFLT(INFO, "\n");

        /* Forget about peer. */
        peer_delete(event->disconnect.conn.conn_handle);

        /* Resume scanning. */
        blecent_scan();
        return 0;

    case BLE_GAP_EVENT_DISC_COMPLETE:
        MODLOG_DFLT(INFO, "discovery complete; reason=%d\n",
                    event->disc_complete.reason);
        return 0;

    case BLE_GAP_EVENT_ENC_CHANGE:
        /* Encryption has been enabled or disabled for this connection. */
        MODLOG_DFLT(INFO, "encryption change event; status=%d ",
                    event->enc_change.status);
        rc = ble_gap_conn_find(event->enc_change.conn_handle, &desc);
        assert(rc == 0);
        print_conn_desc(&desc);
#if CONFIG_EXAMPLE_ENCRYPTION
        /*** Go for service discovery after encryption has been successfully enabled ***/
        rc = peer_disc_all(event->connect.conn_handle,
                           blecent_on_disc_complete, NULL);
        if (rc != 0) {
            MODLOG_DFLT(ERROR, "Failed to discover services; rc=%d\n", rc);
            return 0;
        }
#endif
        return 0;

    case BLE_GAP_EVENT_NOTIFY_RX:
        /* Peer sent us a notification or indication. */
        MODLOG_DFLT(INFO, "received %s; conn_handle=%d attr_handle=%d "
                    "attr_len=%d\n",
                    event->notify_rx.indication ?
                    "indication" :
                    "notification",
                    event->notify_rx.conn_handle,
                    event->notify_rx.attr_handle,
                    OS_MBUF_PKTLEN(event->notify_rx.om));

        /* Attribute data is contained in event->notify_rx.om. Use
         * `os_mbuf_copydata` to copy the data received in notification mbuf */
        return 0;

    case BLE_GAP_EVENT_MTU:
        MODLOG_DFLT(INFO, "mtu update event; conn_handle=%d cid=%d mtu=%d\n",
                    event->mtu.conn_handle,
                    event->mtu.channel_id,
                    event->mtu.value);
        return 0;

    case BLE_GAP_EVENT_REPEAT_PAIRING:
        /* We already have a bond with the peer, but it is attempting to
         * establish a new secure link.  This app sacrifices security for
         * convenience: just throw away the old bond and accept the new link.
         */

        /* Delete the old bond. */
        rc = ble_gap_conn_find(event->repeat_pairing.conn_handle, &desc);
        assert(rc == 0);
        ble_store_util_delete_peer(&desc.peer_id_addr);

        /* Return BLE_GAP_REPEAT_PAIRING_RETRY to indicate that the host should
         * continue with the pairing operation.
         */
        return BLE_GAP_REPEAT_PAIRING_RETRY;

#if CONFIG_EXAMPLE_EXTENDED_ADV
    case BLE_GAP_EVENT_EXT_DISC:
        /* An advertisment report was received during GAP discovery. */
        ext_print_adv_report(&event->disc);

        blecent_connect_if_interesting(&event->disc);
        return 0;
#endif

    default:
        return 0;
    }
}

static void
blecent_on_reset(int reason)
{
    MODLOG_DFLT(ERROR, "Resetting state; reason=%d\n", reason);
}

static void
blecent_on_sync(void)
{
    int rc;

    /* Make sure we have proper identity address set (public preferred) */
    rc = ble_hs_util_ensure_addr(0);
    assert(rc == 0);

#if !CONFIG_EXAMPLE_INIT_DEINIT_LOOP
    /* Begin scanning for a peripheral to connect to. */
    blecent_scan();
#endif
}

void blecent_host_task(void *param)
{
    ESP_LOGI(tag, "BLE Host Task Started");
    /* This function will return only when nimble_port_stop() is executed */
    nimble_port_run();

    nimble_port_freertos_deinit();
}

#if CONFIG_EXAMPLE_INIT_DEINIT_LOOP
/* This function showcases stack init and deinit procedure. */
static void stack_init_deinit(void)
{
    int rc;
    while(1) {

        vTaskDelay(1000);

        ESP_LOGI(tag, "Deinit host");

        rc = nimble_port_stop();
        if (rc == 0) {
            nimble_port_deinit();
        } else {
            ESP_LOGI(tag, "Nimble port stop failed, rc = %d", rc);
            break;
        }

        vTaskDelay(1000);

        ESP_LOGI(tag, "Init host");

        rc = nimble_port_init();
        if (rc != ESP_OK) {
            ESP_LOGI(tag, "Failed to init nimble %d ", rc);
            break;
        }

        nimble_port_freertos_init(blecent_host_task);

        ESP_LOGI(tag, "Waiting for 1 second");
    }
}
#endif

void
app_main(void)
{
    int rc;
    /* Initialize NVS — it is used to store PHY calibration data */
    esp_err_t ret = nvs_flash_init();
    if  (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
        ESP_ERROR_CHECK(nvs_flash_erase());
        ret = nvs_flash_init();
    }
    ESP_ERROR_CHECK(ret);

    ret = nimble_port_init();
    if (ret != ESP_OK) {
        ESP_LOGE(tag, "Failed to init nimble %d ", ret);
        return;
    }

    /* Configure the host. */
    ble_hs_cfg.reset_cb = blecent_on_reset;
    ble_hs_cfg.sync_cb = blecent_on_sync;
    ble_hs_cfg.store_status_cb = ble_store_util_status_rr;

    /* Initialize data structures to track connected peers. */
    rc = peer_init(MYNEWT_VAL(BLE_MAX_CONNECTIONS), 64, 64, 64);
    assert(rc == 0);

    /* Set the default device name. */
    rc = ble_svc_gap_device_name_set("nimble-blecent");
    assert(rc == 0);

    /* XXX Need to have template for store */
    ble_store_config_init();

    nimble_port_freertos_init(blecent_host_task);

#if CONFIG_EXAMPLE_INIT_DEINIT_LOOP
    stack_init_deinit();
#endif

}