btstack/example/sm_pairing_central.c

/*
 * Copyright (C) 2014 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 MATTHIAS
 * RINGWALD 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__ "sm_pairing_central.c"
 

// *****************************************************************************
/* EXAMPLE_START(sm_pairing_central): LE Central - Test Pairing Methods
 *
 * @text Depending on the Authentication requiremens and IO Capabilities,
 * the pairing process uses different short and long term key generation method.
 * This example helps explore the different options incl. LE Secure Connections.
 * It scans for advertisements and connects to the first device that lists a 
 * random service.
 */
 // *****************************************************************************


#include <stdint.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

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


// We're looking for a remote device that lists this service in the advertisement
// LightBlue assigns 0x1111 as the UUID for a Blank service.
#define REMOTE_SERVICE 0x1111

// Fixed passkey - used with sm_pairing_peripheral. Passkey is random in general
#define FIXED_PASSKEY 123456U


static btstack_packet_callback_registration_t hci_event_callback_registration;
static btstack_packet_callback_registration_t sm_event_callback_registration;

/* @section GAP LE setup for receiving advertisements
 *
 * @text GAP LE advertisements are received as custom HCI events of the 
 * GAP_EVENT_ADVERTISING_REPORT type. To receive them, you'll need to register
 * the HCI packet handler, as shown in Listing GAPLEAdvSetup.
 */

/* LISTING_START(GAPLEAdvSetup): Setting up GAP LE client for receiving advertisements */
static void hci_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
static void sm_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);

static void sm_pairing_central_setup(void){
    l2cap_init();

    // setup le device db
    le_device_db_init();

    // setup SM: Display only
    sm_init();

    // setup ATT server
    att_server_init(profile_data, NULL, NULL);

    // setup GATT Client
    gatt_client_init();

    // register handler
    hci_event_callback_registration.callback = &hci_packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    sm_event_callback_registration.callback = &sm_packet_handler;
    sm_add_event_handler(&sm_event_callback_registration);


    // Configuration

    // Enable mandatory authentication for GATT Client
    // - if un-encrypted connections are not supported, e.g. when connecting to own device, this enforces authentication
    // gatt_client_set_required_security_level(LEVEL_2);

    /**
     * Choose ONE of the following configurations
     * Bonding is disabled to allow for repeated testing. It can be enabled by or'ing
     * SM_AUTHREQ_BONDING to the authentication requirements like this:
     * sm_set_authentication_requirements( X | SM_AUTHREQ_BONDING)
     */

    // LE Legacy Pairing, Just Works
    // sm_set_io_capabilities(IO_CAPABILITY_DISPLAY_YES_NO);
    // sm_set_authentication_requirements(0);

    // LE Legacy Pairing, Passkey entry initiator enter, responder (us) displays
    // sm_set_io_capabilities(IO_CAPABILITY_DISPLAY_ONLY);
    // sm_set_authentication_requirements(SM_AUTHREQ_MITM_PROTECTION);
    // sm_use_fixed_passkey_in_display_role(FIXED_PASSKEY);

#ifdef ENABLE_LE_SECURE_CONNECTIONS

    // enable LE Secure Connections Only mode - disables Legacy pairing
    // sm_set_secure_connections_only_mode(true);

    // LE Secure Connections, Just Works
    // sm_set_io_capabilities(IO_CAPABILITY_DISPLAY_YES_NO);
    // sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION);

    // LE Secure Connections, Numeric Comparison
    // sm_set_io_capabilities(IO_CAPABILITY_DISPLAY_YES_NO);
    // sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION|SM_AUTHREQ_MITM_PROTECTION);

    // LE Secure Pairing, Passkey entry initiator (us) enters, responder displays
    // sm_set_io_capabilities(IO_CAPABILITY_KEYBOARD_ONLY);
    // sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION|SM_AUTHREQ_MITM_PROTECTION);
    // sm_use_fixed_passkey_in_display_role(FIXED_PASSKEY);

    // LE Secure Pairing, Passkey entry initiator (us) displays, responder enters
    // sm_set_io_capabilities(IO_CAPABILITY_DISPLAY_ONLY);
    // sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION|SM_AUTHREQ_MITM_PROTECTION);
#endif
}

/* LISTING_END */

/* @section HCI packet handler
 * 
 * @text The HCI packet handler has to start the scanning, 
 * and to handle received advertisements. Advertisements are received 
 * as HCI event packets of the GAP_EVENT_ADVERTISING_REPORT type,
 * see Listing HCIPacketHandler.  
 */

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

static void hci_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;
    hci_con_handle_t con_handle;
    uint8_t status;

    switch (hci_event_packet_get_type(packet)) {
        case BTSTACK_EVENT_STATE:
            // BTstack activated, get started
            if (btstack_event_state_get_state(packet) == HCI_STATE_WORKING){
                printf("Start scaning!\n");
                gap_set_scan_parameters(1,0x0030, 0x0030);
                gap_start_scan(); 
            }
            break;
        case GAP_EVENT_ADVERTISING_REPORT:{
            bd_addr_t address;
            gap_event_advertising_report_get_address(packet, address);
            uint8_t address_type = gap_event_advertising_report_get_address_type(packet);
            uint8_t length = gap_event_advertising_report_get_data_length(packet);
            const uint8_t * data = gap_event_advertising_report_get_data(packet);
            // printf("Advertisement event: addr-type %u, addr %s, data[%u] ",
            //   address_type, bd_addr_to_str(address), length);
            // printf_hexdump(data, length);
            if (!ad_data_contains_uuid16(length, (uint8_t *) data, REMOTE_SERVICE)) break;
            printf("Found remote with UUID %04x, connecting...\n", REMOTE_SERVICE);
            gap_stop_scan();
            gap_connect(address,address_type);
            break;
        }
        case HCI_EVENT_LE_META:
            // wait for connection complete
            if (hci_event_le_meta_get_subevent_code(packet) != HCI_SUBEVENT_LE_CONNECTION_COMPLETE) break;
            con_handle = hci_subevent_le_connection_complete_get_connection_handle(packet);
            printf("Connection complete\n");

            // for testing, choose one of the following actions

            // manually start pairing
            sm_request_pairing(con_handle);

            // gatt client request to authenticated characteristic in sm_pairing_peripheral (short cut, uses hard-coded value handle)
            // gatt_client_read_value_of_characteristic_using_value_handle(&hci_packet_handler, con_handle, 0x0009);

            // general gatt client request to trigger mandatory authentication
            // gatt_client_discover_primary_services(&hci_packet_handler, con_handle);
            break;
        case HCI_EVENT_ENCRYPTION_CHANGE: 
            con_handle = hci_event_encryption_change_get_connection_handle(packet);
            printf("Connection encrypted: %u\n", hci_event_encryption_change_get_encryption_enabled(packet));
            break;
        case GATT_EVENT_QUERY_COMPLETE:
            status = gatt_event_query_complete_get_att_status(packet);
            switch (status){
                case ATT_ERROR_INSUFFICIENT_ENCRYPTION:
                    printf("GATT Query result: Insufficient Encryption\n");
                    break;
                case ATT_ERROR_INSUFFICIENT_AUTHENTICATION:
                    printf("GATT Query result: Insufficient Authentication\n");
                    break;
                case ATT_ERROR_BONDING_INFORMATION_MISSING:
                    printf("GATT Query result: Bonding Information Missing\n");
                    break;
                case ATT_ERROR_SUCCESS:
                    printf("GATT Query result: OK\n");
                    break;
                default:
                    printf("GATT Query result: 0x%02x\n", gatt_event_query_complete_get_att_status(packet));
                    break;
            }
            break;
        default:
            break;
    }
}

/* @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;

    bd_addr_t addr;
    bd_addr_type_t addr_type;

    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_PASSKEY_INPUT_NUMBER:
            printf("Passkey Input requested\n");
            printf("Sending fixed passkey %"PRIu32"\n", (uint32_t) FIXED_PASSKEY);
            sm_passkey_input(sm_event_passkey_input_number_get_handle(packet), FIXED_PASSKEY);
            break;
        case SM_EVENT_PAIRING_STARTED:
            printf("Pairing started\n");
            break;
        case SM_EVENT_PAIRING_COMPLETE:
            switch (sm_event_pairing_complete_get_status(packet)){
                case ERROR_CODE_SUCCESS:
                    printf("Pairing complete, success\n");
                    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, authentication failure with reason = %u\n", sm_event_pairing_complete_get_reason(packet));
                    break;
                default:
                    break;
            }
            break;
        case SM_EVENT_REENCRYPTION_STARTED:
            sm_event_reencryption_complete_get_address(packet, addr);
            printf("Bonding information exists for addr type %u, identity addr %s -> start re-encryption\n",
                   sm_event_reencryption_started_get_addr_type(packet), bd_addr_to_str(addr));
            break;
        case SM_EVENT_REENCRYPTION_COMPLETE:
            switch (sm_event_reencryption_complete_get_status(packet)){
                case ERROR_CODE_SUCCESS:
                    printf("Re-encryption complete, success\n");
                    break;
                case ERROR_CODE_CONNECTION_TIMEOUT:
                    printf("Re-encryption failed, timeout\n");
                    break;
                case ERROR_CODE_REMOTE_USER_TERMINATED_CONNECTION:
                    printf("Re-encryption failed, disconnected\n");
                    break;
                case ERROR_CODE_PIN_OR_KEY_MISSING:
                    printf("Re-encryption failed, bonding information missing\n\n");
                    printf("Assuming remote lost bonding information\n");
                    printf("Deleting local bonding information and start new pairing...\n");
                    sm_event_reencryption_complete_get_address(packet, addr);
                    addr_type = sm_event_reencryption_started_get_addr_type(packet);
                    gap_delete_bonding(addr_type, addr);
                    sm_request_pairing(sm_event_reencryption_complete_get_handle(packet));
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}
/* LISTING_END */

int btstack_main(void);
int btstack_main(void)
{
    sm_pairing_central_setup();

    // turn on!
    hci_power_control(HCI_POWER_ON);
        
    return 0;
}

/* EXAMPLE_END */