/*
* Copyright (C) 2011-2012 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 MATTHIAS RINGWALD 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
*
*/
//
// ATT Server Globals
//
#include "att_server.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "btstack-config.h"
#include <btstack/run_loop.h>
#include "debug.h"
#include "btstack_memory.h"
#include "hci.h"
#include "hci_dump.h"
#include "l2cap.h"
#include "sm.h"
#include "att.h"
#include "att_server.h"
#include "gap_le.h"
#include "central_device_db.h"
static void att_run(void);
typedef enum {
ATT_SERVER_IDLE,
ATT_SERVER_REQUEST_RECEIVED,
ATT_SERVER_W4_SIGNED_WRITE_VALIDATION,
ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED,
} att_server_state_t;
static att_connection_t att_connection;
static att_server_state_t att_server_state;
static uint8_t att_client_addr_type;
static bd_addr_t att_client_address;
static uint16_t att_request_handle = 0;
static uint16_t att_request_size = 0;
static uint8_t att_request_buffer[28];
static int att_ir_central_device_db_index = -1;
static int att_ir_lookup_active = 0;
static int att_handle_value_indication_handle = 0;
static timer_source_t att_handle_value_indication_timer;
static btstack_packet_handler_t att_client_packet_handler = NULL;
static void att_handle_value_indication_notify_client(uint8_t status, uint16_t client_handle, uint16_t attribute_handle){
uint8_t event[7];
int pos = 0;
event[pos++] = ATT_HANDLE_VALUE_INDICATION_COMPLETE;
event[pos++] = sizeof(event) - 2;
event[pos++] = status;
bt_store_16(event, pos, client_handle);
pos += 2;
bt_store_16(event, pos, attribute_handle);
pos += 2;
(*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event));
}
static void att_handle_value_indication_timeout(timer_source_t *ts){
uint16_t att_handle = att_handle_value_indication_handle;
att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_request_handle, att_handle);
}
static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
switch (packet_type) {
case HCI_EVENT_PACKET:
switch (packet[0]) {
case DAEMON_EVENT_HCI_PACKET_SENT:
att_run();
break;
case HCI_EVENT_LE_META:
switch (packet[2]) {
case HCI_SUBEVENT_LE_CONNECTION_COMPLETE:
// store connection info
att_request_handle = READ_BT_16(packet, 4);
att_client_addr_type = packet[7];
bt_flip_addr(att_client_address, &packet[8]);
// reset connection properties
att_connection.mtu = 23;
att_connection.encryption_key_size = 0;
att_connection.authenticated = 0;
att_connection.authorized = 0;
break;
default:
break;
}
break;
case HCI_EVENT_ENCRYPTION_CHANGE:
// check handle
if (att_request_handle != READ_BT_16(packet, 3)) break;
att_connection.encryption_key_size = sm_encryption_key_size(att_client_addr_type, att_client_address);
att_connection.authenticated = sm_authenticated(att_client_addr_type, att_client_address);
break;
case HCI_EVENT_DISCONNECTION_COMPLETE:
// restart advertising if we have been connected before
// -> avoid sending advertise enable a second time before command complete was received
att_server_state = ATT_SERVER_IDLE;
att_request_handle = 0;
att_handle_value_indication_handle = 0; // reset error state
att_clear_transaction_queue();
break;
case SM_IDENTITY_RESOLVING_STARTED:
printf("SM_IDENTITY_RESOLVING_STARTED\n");
att_ir_lookup_active = 1;
break;
case SM_IDENTITY_RESOLVING_SUCCEEDED:
att_ir_lookup_active = 0;
att_ir_central_device_db_index = ((sm_event_t*) packet)->central_device_db_index;
printf("SM_IDENTITY_RESOLVING_SUCCEEDED id %u\n", att_ir_central_device_db_index);
att_run();
break;
case SM_IDENTITY_RESOLVING_FAILED:
printf("SM_IDENTITY_RESOLVING_FAILED\n");
att_ir_lookup_active = 0;
att_ir_central_device_db_index = -1;
att_run();
break;
case SM_AUTHORIZATION_RESULT: {
sm_event_t * event = (sm_event_t *) packet;
if (event->addr_type != att_client_addr_type) break;
if (memcmp(event->address, att_client_address, 6) != 0) break;
att_connection.authorized = event->authorization_result;
att_run();
break;
}
default:
break;
}
}
if (att_client_packet_handler){
att_client_packet_handler(packet_type, channel, packet, size);
}
}
static void att_signed_write_handle_cmac_result(uint8_t hash[8]){
if (att_server_state != ATT_SERVER_W4_SIGNED_WRITE_VALIDATION) return;
if (memcmp(hash, &att_request_buffer[att_request_size-8], 8)){
printf("ATT Signed Write, invalid signature\n");
att_server_state = ATT_SERVER_IDLE;
return;
}
// update sequence number
uint32_t counter_packet = READ_BT_32(att_request_buffer, att_request_size-12);
central_device_db_counter_set(att_ir_central_device_db_index, counter_packet+1);
att_server_state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED;
att_run();
}
static void att_run(void){
switch (att_server_state){
case ATT_SERVER_IDLE:
case ATT_SERVER_W4_SIGNED_WRITE_VALIDATION:
return;
case ATT_SERVER_REQUEST_RECEIVED:
if (att_request_buffer[0] == ATT_SIGNED_WRITE_COMAND){
printf("ATT Signed Write!\n");
if (!sm_cmac_ready()) {
printf("ATT Signed Write, sm_cmac engine not ready. Abort\n");
att_server_state = ATT_SERVER_IDLE;
return;
}
if (att_request_size < (3 + 12)) {
printf("ATT Signed Write, request to short. Abort.\n");
att_server_state = ATT_SERVER_IDLE;
return;
}
if (att_ir_lookup_active){
return;
}
if (att_ir_central_device_db_index < 0){
printf("ATT Signed Write, CSRK not available\n");
att_server_state = ATT_SERVER_IDLE;
return;
}
// check counter
uint32_t counter_packet = READ_BT_32(att_request_buffer, att_request_size-12);
uint32_t counter_db = central_device_db_counter_get(att_ir_central_device_db_index);
printf("ATT Signed Write, DB counter %u, packet counter %u\n", counter_db, counter_packet);
if (counter_packet < counter_db){
printf("ATT Signed Write, db reports higher counter, abort\n");
att_server_state = ATT_SERVER_IDLE;
return;
}
// signature is { sequence counter, secure hash }
sm_key_t csrk;
central_device_db_csrk(att_ir_central_device_db_index, csrk);
att_server_state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION;
printf("Orig Signature: ");
hexdump( &att_request_buffer[att_request_size-8], 8);
sm_cmac_start(csrk, att_request_size - 8, att_request_buffer, att_signed_write_handle_cmac_result);
return;
}
// NOTE: fall through for regular commands
case ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED:
if (!hci_can_send_packet_now(HCI_ACL_DATA_PACKET)) return;
uint8_t att_response_buffer[28];
uint16_t att_response_size = att_handle_request(&att_connection, att_request_buffer, att_request_size, att_response_buffer);
// intercept "insufficient authorization" for authenticated connections to allow for user authorization
if (att_response_buffer[0] == ATT_ERROR_RESPONSE
&& att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION
&& att_connection.authenticated){
switch (sm_authorization_state(att_client_addr_type, att_client_address)){
case AUTHORIZATION_UNKNOWN:
sm_request_authorization(att_client_addr_type, att_client_address);
return;
case AUTHORIZATION_PENDING:
return;
default:
break;
}
}
att_server_state = ATT_SERVER_IDLE;
if (att_response_size == 0) return;
l2cap_send_connectionless(att_request_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_buffer, att_response_size);
break;
}
}
static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
if (packet_type != ATT_DATA_PACKET) return;
// handle value indication confirms
if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_handle_value_indication_handle){
run_loop_remove_timer(&att_handle_value_indication_timer);
uint16_t att_handle = att_handle_value_indication_handle;
att_handle_value_indication_handle = 0;
att_handle_value_indication_notify_client(0, att_request_handle, att_handle);
return;
}
// check size
if (size > sizeof(att_request_buffer)) return;
// last request still in processing?
if (att_server_state != ATT_SERVER_IDLE) return;
// store request
att_server_state = ATT_SERVER_REQUEST_RECEIVED;
att_request_size = size;
memcpy(att_request_buffer, packet, size);
att_run();
}
void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){
sm_register_packet_handler(att_event_packet_handler);
l2cap_register_fixed_channel(att_packet_handler, L2CAP_CID_ATTRIBUTE_PROTOCOL);
att_server_state = ATT_SERVER_IDLE;
att_set_db(db);
att_set_read_callback(read_callback);
att_set_write_callback(write_callback);
}
void att_server_register_packet_handler(btstack_packet_handler_t handler){
att_client_packet_handler = handler;
}
int att_server_can_send(){
if (att_request_handle == 0) return 0;
return hci_can_send_packet_now(HCI_ACL_DATA_PACKET);
}
int att_server_notify(uint16_t handle, uint8_t *value, uint16_t value_len){
uint8_t packet_buffer[att_connection.mtu];
uint16_t size = att_prepare_handle_value_notification(&att_connection, handle, value, value_len, packet_buffer);
return l2cap_send_connectionless(att_request_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, packet_buffer, size);
}
int att_server_indicate(uint16_t handle, uint8_t *value, uint16_t value_len){
if (att_handle_value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PORGRESS;
if (!hci_can_send_packet_now(HCI_ACL_DATA_PACKET)) return BTSTACK_ACL_BUFFERS_FULL;
// track indication
att_handle_value_indication_handle = handle;
run_loop_set_timer_handler(&att_handle_value_indication_timer, att_handle_value_indication_timeout);
run_loop_set_timer(&att_handle_value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS);
run_loop_add_timer(&att_handle_value_indication_timer);
uint8_t packet_buffer[att_connection.mtu];
uint16_t size = att_prepare_handle_value_indication(&att_connection, handle, value, value_len, packet_buffer);
l2cap_send_connectionless(att_request_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, packet_buffer, size);
return 0;
}