btstack/example/hog_host_demo.c

/*
 * Copyright (C) 2020 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at
 * contact@bluekitchen-gmbh.com
 *
 */

#define BTSTACK_FILE__ "hog_host_demo.c"

/*
 * hog_host_demo.c
 */

/* EXAMPLE_START(hog_host_demo): HID Host LE
 *
 * @text This example implements a minimal HID-over-GATT Host. It scans for LE HID devices, connects to it,
 * discovers the Characteristics relevant for the HID Service and enables Notifications on them.
 * It then dumps all Boot Keyboard and Mouse Input Reports
 */

#include <inttypes.h>
#include <stdio.h>
#include <btstack_tlv.h>

#include "btstack_config.h"
#include "btstack.h"

// hog_host_demo.gatt contains the declaration of the provided GATT Services + Characteristics
// hog_host_demo.h    contains the binary representation of gatt_browser.gatt
// it is generated by the build system by calling: $BTSTACK_ROOT/tool/compile_gatt.py hog_host_demo.gatt hog_host_demo.h
// it needs to be regenerated when the GATT Database declared in gatt_browser.gatt file is modified
#include "hog_host_demo.h"

// TAG to store remote device address and type in TLV
#define TLV_TAG_HOGD ((((uint32_t) 'H') << 24 ) | (((uint32_t) 'O') << 16) | (((uint32_t) 'G') << 8) | 'D')

typedef struct {
    bd_addr_t addr;
    bd_addr_type_t addr_type;
} le_device_addr_t;

static enum {
    W4_WORKING,
    W4_HID_DEVICE_FOUND,
    W4_CONNECTED,
    W4_ENCRYPTED,
    W4_HID_CLIENT_CONNECTED,
    READY,
    W4_TIMEOUT_THEN_SCAN,
    W4_TIMEOUT_THEN_RECONNECT,
} app_state;

static le_device_addr_t remote_device;
static hci_con_handle_t connection_handle;
static uint16_t hids_cid;
static hid_protocol_mode_t protocol_mode = HID_PROTOCOL_MODE_REPORT;

// SDP
static uint8_t hid_descriptor_storage[500];

// used to implement connection timeout and reconnect timer
static btstack_timer_source_t connection_timer;

// register for events from HCI/GAP and SM
static btstack_packet_callback_registration_t hci_event_callback_registration;
static btstack_packet_callback_registration_t sm_event_callback_registration;

// used to store remote device in TLV
static const btstack_tlv_t * btstack_tlv_singleton_impl;
static void *                btstack_tlv_singleton_context;

// Simplified US Keyboard with Shift modifier

#define CHAR_ILLEGAL     0xff
#define CHAR_RETURN     '\n'
#define CHAR_ESCAPE      27
#define CHAR_TAB         '\t'
#define CHAR_BACKSPACE   0x7f

/**
 * English (US)
 */
static const uint8_t keytable_us_none [] = {
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*   0-3 */
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',                   /*  4-13 */
        'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',                   /* 14-23 */
        'u', 'v', 'w', 'x', 'y', 'z',                                       /* 24-29 */
        '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',                   /* 30-39 */
        CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
        '-', '=', '[', ']', '\\', CHAR_ILLEGAL, ';', '\'', 0x60, ',',       /* 45-54 */
        '.', '/', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
        '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
        '6', '7', '8', '9', '0', '.', 0xa7,                                 /* 97-100 */
};

static const uint8_t keytable_us_shift[] = {
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*  0-3  */
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',                   /*  4-13 */
        'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',                   /* 14-23 */
        'U', 'V', 'W', 'X', 'Y', 'Z',                                       /* 24-29 */
        '!', '@', '#', '$', '%', '^', '&', '*', '(', ')',                   /* 30-39 */
        CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
        '_', '+', '{', '}', '|', CHAR_ILLEGAL, ':', '"', 0x7E, '<',         /* 45-54 */
        '>', '?', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
        CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
        '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
        '6', '7', '8', '9', '0', '.', 0xb1,                                 /* 97-100 */
};



#define NUM_KEYS 6
static uint8_t last_keys[NUM_KEYS];
static void hid_handle_input_report(uint8_t service_index, const uint8_t * report, uint16_t report_len){
    // check if HID Input Report
    
    if (report_len < 1) return;
    
    btstack_hid_parser_t parser;
    
    switch (protocol_mode){
        case HID_PROTOCOL_MODE_BOOT:
            btstack_hid_parser_init(&parser,
                                    btstack_hid_get_boot_descriptor_data(),
                                    btstack_hid_get_boot_descriptor_len(),
                                    HID_REPORT_TYPE_INPUT, report, report_len);
            break;

        default:
            btstack_hid_parser_init(&parser, 
                hids_client_descriptor_storage_get_descriptor_data(hids_cid, service_index), 
                hids_client_descriptor_storage_get_descriptor_len(hids_cid, service_index), 
                HID_REPORT_TYPE_INPUT, report, report_len);
            break;

    }
    
    int shift = 0;
    uint8_t new_keys[NUM_KEYS];
    memset(new_keys, 0, sizeof(new_keys));
    int     new_keys_count = 0;
    while (btstack_hid_parser_has_more(&parser)){
        uint16_t usage_page;
        uint16_t usage;
        int32_t  value;
        btstack_hid_parser_get_field(&parser, &usage_page, &usage, &value);
        if (usage_page != 0x07) continue;   
        switch (usage){
            case 0xe1:
            case 0xe6:
                if (value){
                    shift = 1;
                }
                continue;
            case 0x00:
                continue;
            default:
                break;
        }
        if (usage >= sizeof(keytable_us_none)) continue;

        // store new keys
        new_keys[new_keys_count++] = (uint8_t) usage;

        // check if usage was used last time (and ignore in that case)
        int i;
        for (i=0;i<NUM_KEYS;i++){
            if (usage == last_keys[i]){
                usage = 0;
            }
        }
        if (usage == 0) continue;

        uint8_t key;
        if (shift){
            key = keytable_us_shift[usage];
        } else {
            key = keytable_us_none[usage];
        }
        if (key == CHAR_ILLEGAL) continue;
        if (key == CHAR_BACKSPACE){ 
            printf("\b \b");    // go back one char, print space, go back one char again
            continue;
        }
        printf("%c", key);
    }
    memcpy(last_keys, new_keys, NUM_KEYS);
}

/**
 * @section Test if advertisement contains HID UUID
 * @param packet
 * @param size
 * @returns true if it does
 */
static bool adv_event_contains_hid_service(const uint8_t * packet){
    const uint8_t * ad_data = gap_event_advertising_report_get_data(packet);
    uint8_t ad_len = gap_event_advertising_report_get_data_length(packet);
    return ad_data_contains_uuid16(ad_len, ad_data, ORG_BLUETOOTH_SERVICE_HUMAN_INTERFACE_DEVICE);
}

/**
 * Start scanning
 */
static void hog_start_scan(void){
    printf("Scanning for LE HID devices...\n");
    app_state = W4_HID_DEVICE_FOUND;
    // Passive scanning, 100% (scan interval = scan window)
    gap_set_scan_parameters(0,48,48);
    gap_start_scan();
}

/**
 * Handle timeout for outgoing connection
 * @param ts
 */
static void hog_connection_timeout(btstack_timer_source_t * ts){
    UNUSED(ts);
    printf("Timeout - abort connection\n");
    gap_connect_cancel();
    hog_start_scan();
}


/**
 * Connect to remote device but set timer for timeout
 */
static void hog_connect(void) {
    // set timer
    btstack_run_loop_set_timer(&connection_timer, 10000);
    btstack_run_loop_set_timer_handler(&connection_timer, &hog_connection_timeout);
    btstack_run_loop_add_timer(&connection_timer);
    app_state = W4_CONNECTED;
    gap_connect(remote_device.addr, remote_device.addr_type);
}

/**
 * Handle timer event to trigger reconnect
 * @param ts
 */
static void hog_reconnect_timeout(btstack_timer_source_t * ts){
    UNUSED(ts);
    switch (app_state){
        case W4_TIMEOUT_THEN_RECONNECT:
            hog_connect();
            break;
        case W4_TIMEOUT_THEN_SCAN:
            hog_start_scan();
            break;
        default:
            break;
    }
}

/**
 * Start connecting after boot up: connect to last used device if possible, start scan otherwise
 */
static void hog_start_connect(void){
    // check if we have a bonded device
    btstack_tlv_get_instance(&btstack_tlv_singleton_impl, &btstack_tlv_singleton_context);
    if (btstack_tlv_singleton_impl){
        int len = btstack_tlv_singleton_impl->get_tag(btstack_tlv_singleton_context, TLV_TAG_HOGD, (uint8_t *) &remote_device, sizeof(remote_device));
        if (len == sizeof(remote_device)){
            printf("Bonded, connect to device with %s address %s ...\n", remote_device.addr_type == 0 ? "public" : "random" , bd_addr_to_str(remote_device.addr));
            hog_connect();
            return;
        }
    }
    // otherwise, scan for HID devices
    hog_start_scan();
}

/**
 * In case of error, disconnect and start scanning again
 */
static void handle_outgoing_connection_error(void){
    printf("Error occurred, disconnect and start over\n");
    gap_disconnect(connection_handle);
    hog_start_scan();
}

/**
 * Handle GATT Client Events dependent on current state
 *
 * @param packet_type
 * @param channel
 * @param packet
 * @param size
 */
static void handle_gatt_client_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) {
    UNUSED(packet_type);
    UNUSED(channel);
    UNUSED(size);

    uint8_t status;

    if (hci_event_packet_get_type(packet) != HCI_EVENT_GATTSERVICE_META){
        return;
    }
    
    switch (hci_event_gattservice_meta_get_subevent_code(packet)){
        case GATTSERVICE_SUBEVENT_HID_SERVICE_CONNECTED:
            status = gattservice_subevent_hid_service_connected_get_status(packet);
            switch (status){
                case ERROR_CODE_SUCCESS:
                    printf("HID service client connected, found %d services\n", 
                        gattservice_subevent_hid_service_connected_get_num_instances(packet));
        
                                        // store device as bonded
                    if (btstack_tlv_singleton_impl){
                        btstack_tlv_singleton_impl->store_tag(btstack_tlv_singleton_context, TLV_TAG_HOGD, (const uint8_t *) &remote_device, sizeof(remote_device));
                    }
                    // done
                    printf("Ready - please start typing or mousing..\n");
                    app_state = READY;
                    break;
                default:
                    printf("HID service client connection failed, status 0x%02x.\n", status);
                    handle_outgoing_connection_error();
                    break;
            }
            break;

        case GATTSERVICE_SUBEVENT_HID_SERVICE_DISCONNECTED:
            printf("HID service client disconnected\n");
            hog_start_connect();
            break;

        case GATTSERVICE_SUBEVENT_HID_REPORT:
            hid_handle_input_report(
                gattservice_subevent_hid_report_get_service_index(packet),
                gattservice_subevent_hid_report_get_report(packet), 
                gattservice_subevent_hid_report_get_report_len(packet));
            break;

        default:
            break;
    }
}

/* LISTING_START(packetHandler): Packet Handler */
static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    /* LISTING_PAUSE */
    UNUSED(channel);
    UNUSED(size);
    uint8_t event;
    /* LISTING_RESUME */
    switch (packet_type) {
        case HCI_EVENT_PACKET:
            event = hci_event_packet_get_type(packet);
            switch (event) {
                case BTSTACK_EVENT_STATE:
                    if (btstack_event_state_get_state(packet) != HCI_STATE_WORKING) break;
                    btstack_assert(app_state == W4_WORKING);
                    
                    hog_start_connect();
                    break;
                case GAP_EVENT_ADVERTISING_REPORT:
                    if (app_state != W4_HID_DEVICE_FOUND) break;
                    if (adv_event_contains_hid_service(packet) == false) break;
                    // stop scan
                    gap_stop_scan();
                    // store remote device address and type
                    gap_event_advertising_report_get_address(packet, remote_device.addr);
                    remote_device.addr_type = gap_event_advertising_report_get_address_type(packet);
                    // connect
                    printf("Found, connect to device with %s address %s ...\n", remote_device.addr_type == 0 ? "public" : "random" , bd_addr_to_str(remote_device.addr));
                    hog_connect();
                    break;
                case HCI_EVENT_DISCONNECTION_COMPLETE:
                    if (app_state != READY) break;
                    connection_handle = HCI_CON_HANDLE_INVALID;
                    switch (app_state){
                        case READY:
                            printf("\nDisconnected, try to reconnect...\n");
                            app_state = W4_TIMEOUT_THEN_RECONNECT;
                            break;
                        default:
                            printf("\nDisconnected, start over...\n");
                            app_state = W4_TIMEOUT_THEN_SCAN;
                            break;
                    }
                    // set timer
                    btstack_run_loop_set_timer(&connection_timer, 100);
                    btstack_run_loop_set_timer_handler(&connection_timer, &hog_reconnect_timeout);
                    btstack_run_loop_add_timer(&connection_timer);
                    break;
                case HCI_EVENT_META_GAP:
                    // wait for connection complete
                    if (hci_event_gap_meta_get_subevent_code(packet) != GAP_SUBEVENT_LE_CONNECTION_COMPLETE) break;
                    if (app_state != W4_CONNECTED) return;
                    btstack_run_loop_remove_timer(&connection_timer);
                    connection_handle = gap_subevent_le_connection_complete_get_connection_handle(packet);
                    // request security
                    app_state = W4_ENCRYPTED;
                    sm_request_pairing(connection_handle);
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}
/* LISTING_END */

/* @section HCI packet handler
 *
 * @text The SM packet handler receives Security Manager Events required for pairing.
 * It also receives events generated during Identity Resolving
 * see Listing SMPacketHandler.
 */

/* LISTING_START(SMPacketHandler): Scanning and receiving advertisements */

static void sm_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(channel);
    UNUSED(size);

    if (packet_type != HCI_EVENT_PACKET) return;

    bool connect_to_service = false;

    switch (hci_event_packet_get_type(packet)) {
        case SM_EVENT_JUST_WORKS_REQUEST:
            printf("Just works requested\n");
            sm_just_works_confirm(sm_event_just_works_request_get_handle(packet));
            break;
        case SM_EVENT_NUMERIC_COMPARISON_REQUEST:
            printf("Confirming numeric comparison: %"PRIu32"\n", sm_event_numeric_comparison_request_get_passkey(packet));
            sm_numeric_comparison_confirm(sm_event_passkey_display_number_get_handle(packet));
            break;
        case SM_EVENT_PASSKEY_DISPLAY_NUMBER:
            printf("Display Passkey: %"PRIu32"\n", sm_event_passkey_display_number_get_passkey(packet));
            break;
        case SM_EVENT_PAIRING_COMPLETE:
            switch (sm_event_pairing_complete_get_status(packet)){
                case ERROR_CODE_SUCCESS:
                    printf("Pairing complete, success\n");
                    connect_to_service = true;
                    break;
                case ERROR_CODE_CONNECTION_TIMEOUT:
                    printf("Pairing failed, timeout\n");
                    break;
                case ERROR_CODE_REMOTE_USER_TERMINATED_CONNECTION:
                    printf("Pairing failed, disconnected\n");
                    break;
                case ERROR_CODE_AUTHENTICATION_FAILURE:
                    printf("Pairing failed, reason = %u\n", sm_event_pairing_complete_get_reason(packet));
                    break;
                default:
                    break;
            }
            break;
        case SM_EVENT_REENCRYPTION_COMPLETE:
            printf("Re-encryption complete, success\n");
            connect_to_service = true;
            break;
        default:
            break;
    }

    if (connect_to_service){
        // continue - query primary services
        printf("Search for HID service.\n");
        app_state = W4_HID_CLIENT_CONNECTED;
        hids_client_connect(connection_handle, handle_gatt_client_event, protocol_mode, &hids_cid);
    }
}
/* LISTING_END */

int btstack_main(int argc, const char * argv[]);
int btstack_main(int argc, const char * argv[]){

    (void)argc;
    (void)argv;

    /* LISTING_START(HogBootHostSetup): HID-over-GATT Host Setup */

    l2cap_init();

    // setup SM: Display only
    sm_init();
    sm_set_io_capabilities(IO_CAPABILITY_DISPLAY_ONLY);
    sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION | SM_AUTHREQ_BONDING);

    //
    gatt_client_init();

    // setup ATT server - only needed if LE Peripheral does ATT queries on its own, e.g. Android and iOS
    att_server_init(profile_data, NULL, NULL);

    hids_client_init(hid_descriptor_storage, sizeof(hid_descriptor_storage));

    // register for events from HCI
    hci_event_callback_registration.callback = &packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    // register for events from Security Manager
    sm_event_callback_registration.callback = &sm_packet_handler;
    sm_add_event_handler(&sm_event_callback_registration);
    sm_set_authentication_requirements( SM_AUTHREQ_BONDING);

    /* LISTING_END */

    // Disable stdout buffering
	setvbuf(stdin, NULL, _IONBF, 0);

    app_state = W4_WORKING;

    // Turn on the device
    hci_power_control(HCI_POWER_ON);
    return 0;
}

/* EXAMPLE_END */