1 /* 2 * Copyright (C) 2014 BlueKitchen GmbH 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the copyright holders nor the names of 14 * contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 4. Any redistribution, use, or modification is done solely for 17 * personal benefit and not for any commercial purpose or for 18 * monetary gain. 19 * 20 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS 24 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 27 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 30 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * Please inquire about commercial licensing options at 34 * [email protected] 35 * 36 */ 37 38 39 // 40 // ATT Server Globals 41 // 42 43 #include <stdint.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <inttypes.h> 48 49 #include "btstack-config.h" 50 51 #include "run_loop.h" 52 #include "btstack_debug.h" 53 #include "btstack_memory.h" 54 #include "hci.h" 55 #include "hci_dump.h" 56 57 #include "l2cap.h" 58 59 #include "ble/sm.h" 60 #include "ble/att.h" 61 #include "att_dispatch.h" 62 #include "gap.h" 63 #include "ble/le_device_db.h" 64 65 #include "ble/att_server.h" 66 67 static void att_run(void); 68 69 // max ATT request matches L2CAP PDU -- allow to use smaller buffer 70 #ifndef ATT_REQUEST_BUFFER_SIZE 71 #define ATT_REQUEST_BUFFER_SIZE HCI_ACL_PAYLOAD_SIZE 72 #endif 73 74 typedef enum { 75 ATT_SERVER_IDLE, 76 ATT_SERVER_REQUEST_RECEIVED, 77 ATT_SERVER_W4_SIGNED_WRITE_VALIDATION, 78 ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED, 79 } att_server_state_t; 80 81 static att_connection_t att_connection; 82 static att_server_state_t att_server_state; 83 84 static uint8_t att_client_addr_type; 85 static bd_addr_t att_client_address; 86 static uint16_t att_request_size = 0; 87 static uint8_t att_request_buffer[ATT_REQUEST_BUFFER_SIZE]; 88 89 static int att_ir_le_device_db_index = -1; 90 static int att_ir_lookup_active = 0; 91 92 static int att_handle_value_indication_handle = 0; 93 static timer_source_t att_handle_value_indication_timer; 94 95 static btstack_packet_handler_t att_client_packet_handler = NULL; 96 97 static void att_handle_value_indication_notify_client(uint8_t status, uint16_t client_handle, uint16_t attribute_handle){ 98 99 if (!att_client_packet_handler) return; 100 101 uint8_t event[7]; 102 int pos = 0; 103 event[pos++] = ATT_HANDLE_VALUE_INDICATION_COMPLETE; 104 event[pos++] = sizeof(event) - 2; 105 event[pos++] = status; 106 bt_store_16(event, pos, client_handle); 107 pos += 2; 108 bt_store_16(event, pos, attribute_handle); 109 pos += 2; 110 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 111 } 112 113 static void att_emit_mtu_event(uint16_t handle, uint16_t mtu){ 114 115 if (!att_client_packet_handler) return; 116 117 uint8_t event[6]; 118 int pos = 0; 119 event[pos++] = ATT_MTU_EXCHANGE_COMPLETE; 120 event[pos++] = sizeof(event) - 2; 121 bt_store_16(event, pos, handle); 122 pos += 2; 123 bt_store_16(event, pos, mtu); 124 pos += 2; 125 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 126 } 127 128 static void att_handle_value_indication_timeout(timer_source_t *ts){ 129 uint16_t att_handle = att_handle_value_indication_handle; 130 att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_connection.con_handle, att_handle); 131 } 132 133 static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ 134 135 bd_addr_t event_address; 136 switch (packet_type) { 137 138 case HCI_EVENT_PACKET: 139 switch (packet[0]) { 140 141 case DAEMON_EVENT_HCI_PACKET_SENT: 142 att_run(); 143 break; 144 145 case HCI_EVENT_LE_META: 146 switch (packet[2]) { 147 case HCI_SUBEVENT_LE_CONNECTION_COMPLETE: 148 // store connection info 149 att_client_addr_type = packet[7]; 150 bt_flip_addr(att_client_address, &packet[8]); 151 // reset connection properties 152 att_connection.con_handle = READ_BT_16(packet, 4); 153 att_connection.mtu = ATT_DEFAULT_MTU; 154 att_connection.max_mtu = l2cap_max_le_mtu(); 155 if (att_connection.max_mtu > ATT_REQUEST_BUFFER_SIZE){ 156 att_connection.max_mtu = ATT_REQUEST_BUFFER_SIZE; 157 } 158 att_connection.encryption_key_size = 0; 159 att_connection.authenticated = 0; 160 att_connection.authorized = 0; 161 break; 162 163 default: 164 break; 165 } 166 break; 167 168 case HCI_EVENT_ENCRYPTION_CHANGE: 169 case HCI_EVENT_ENCRYPTION_KEY_REFRESH_COMPLETE: 170 // check handle 171 if (att_connection.con_handle != READ_BT_16(packet, 3)) break; 172 att_connection.encryption_key_size = sm_encryption_key_size(att_connection.con_handle); 173 att_connection.authenticated = sm_authenticated(att_connection.con_handle); 174 break; 175 176 case HCI_EVENT_DISCONNECTION_COMPLETE: 177 att_clear_transaction_queue(&att_connection); 178 att_connection.con_handle = 0; 179 att_handle_value_indication_handle = 0; // reset error state 180 // restart advertising if we have been connected before 181 // -> avoid sending advertise enable a second time before command complete was received 182 att_server_state = ATT_SERVER_IDLE; 183 break; 184 185 case SM_IDENTITY_RESOLVING_STARTED: 186 log_info("SM_IDENTITY_RESOLVING_STARTED"); 187 att_ir_lookup_active = 1; 188 break; 189 case SM_IDENTITY_RESOLVING_SUCCEEDED: 190 att_ir_lookup_active = 0; 191 att_ir_le_device_db_index = READ_BT_16(packet, 11); 192 log_info("SM_IDENTITY_RESOLVING_SUCCEEDED id %u", att_ir_le_device_db_index); 193 att_run(); 194 break; 195 case SM_IDENTITY_RESOLVING_FAILED: 196 log_info("SM_IDENTITY_RESOLVING_FAILED"); 197 att_ir_lookup_active = 0; 198 att_ir_le_device_db_index = -1; 199 att_run(); 200 break; 201 202 case SM_AUTHORIZATION_RESULT: { 203 if (packet[4] != att_client_addr_type) break; 204 bt_flip_addr(event_address, &packet[5]); 205 if (memcmp(event_address, att_client_address, 6) != 0) break; 206 att_connection.authorized = packet[11]; 207 att_run(); 208 break; 209 } 210 211 default: 212 break; 213 } 214 } 215 if (att_client_packet_handler){ 216 att_client_packet_handler(packet_type, channel, packet, size); 217 } 218 } 219 220 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){ 221 222 if (att_server_state != ATT_SERVER_W4_SIGNED_WRITE_VALIDATION) return; 223 224 uint8_t hash_flipped[8]; 225 swap64(hash, hash_flipped); 226 if (memcmp(hash_flipped, &att_request_buffer[att_request_size-8], 8)){ 227 log_info("ATT Signed Write, invalid signature"); 228 att_server_state = ATT_SERVER_IDLE; 229 return; 230 } 231 log_info("ATT Signed Write, valid signature"); 232 233 // update sequence number 234 uint32_t counter_packet = READ_BT_32(att_request_buffer, att_request_size-12); 235 le_device_db_remote_counter_set(att_ir_le_device_db_index, counter_packet+1); 236 att_server_state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 237 att_run(); 238 } 239 240 static void att_run(void){ 241 switch (att_server_state){ 242 case ATT_SERVER_IDLE: 243 case ATT_SERVER_W4_SIGNED_WRITE_VALIDATION: 244 return; 245 case ATT_SERVER_REQUEST_RECEIVED: 246 if (att_request_buffer[0] == ATT_SIGNED_WRITE_COMMAND){ 247 log_info("ATT Signed Write!"); 248 if (!sm_cmac_ready()) { 249 log_info("ATT Signed Write, sm_cmac engine not ready. Abort"); 250 att_server_state = ATT_SERVER_IDLE; 251 return; 252 } 253 if (att_request_size < (3 + 12)) { 254 log_info("ATT Signed Write, request to short. Abort."); 255 att_server_state = ATT_SERVER_IDLE; 256 return; 257 } 258 if (att_ir_lookup_active){ 259 return; 260 } 261 if (att_ir_le_device_db_index < 0){ 262 log_info("ATT Signed Write, CSRK not available"); 263 att_server_state = ATT_SERVER_IDLE; 264 return; 265 } 266 267 // check counter 268 uint32_t counter_packet = READ_BT_32(att_request_buffer, att_request_size-12); 269 uint32_t counter_db = le_device_db_remote_counter_get(att_ir_le_device_db_index); 270 log_info("ATT Signed Write, DB counter %"PRIu32", packet counter %"PRIu32, counter_db, counter_packet); 271 if (counter_packet < counter_db){ 272 log_info("ATT Signed Write, db reports higher counter, abort"); 273 att_server_state = ATT_SERVER_IDLE; 274 return; 275 } 276 277 // signature is { sequence counter, secure hash } 278 sm_key_t csrk; 279 le_device_db_remote_csrk_get(att_ir_le_device_db_index, csrk); 280 att_server_state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION; 281 log_info("Orig Signature: "); 282 hexdump( &att_request_buffer[att_request_size-8], 8); 283 uint16_t attribute_handle = READ_BT_16(att_request_buffer, 1); 284 sm_cmac_start(csrk, att_request_buffer[0], attribute_handle, att_request_size - 15, &att_request_buffer[3], counter_packet, att_signed_write_handle_cmac_result); 285 return; 286 } 287 // NOTE: fall through for regular commands 288 289 case ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED: 290 if (!l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle)) return; 291 292 l2cap_reserve_packet_buffer(); 293 uint8_t * att_response_buffer = l2cap_get_outgoing_buffer(); 294 uint16_t att_response_size = att_handle_request(&att_connection, att_request_buffer, att_request_size, att_response_buffer); 295 296 // intercept "insufficient authorization" for authenticated connections to allow for user authorization 297 if ((att_response_size >= 4) 298 && (att_response_buffer[0] == ATT_ERROR_RESPONSE) 299 && (att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION) 300 && (att_connection.authenticated)){ 301 302 switch (sm_authorization_state(att_connection.con_handle)){ 303 case AUTHORIZATION_UNKNOWN: 304 l2cap_release_packet_buffer(); 305 sm_request_pairing(att_connection.con_handle); 306 return; 307 case AUTHORIZATION_PENDING: 308 l2cap_release_packet_buffer(); 309 return; 310 default: 311 break; 312 } 313 } 314 315 att_server_state = ATT_SERVER_IDLE; 316 if (att_response_size == 0) { 317 l2cap_release_packet_buffer(); 318 return; 319 } 320 321 l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_size); 322 323 // notify client about MTU exchange result 324 if (att_response_buffer[0] == ATT_EXCHANGE_MTU_RESPONSE){ 325 att_emit_mtu_event(att_connection.con_handle, att_connection.mtu); 326 } 327 328 break; 329 } 330 } 331 332 static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ 333 if (packet_type != ATT_DATA_PACKET) return; 334 335 // handle value indication confirms 336 if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_handle_value_indication_handle){ 337 run_loop_remove_timer(&att_handle_value_indication_timer); 338 uint16_t att_handle = att_handle_value_indication_handle; 339 att_handle_value_indication_handle = 0; 340 att_handle_value_indication_notify_client(0, att_connection.con_handle, att_handle); 341 return; 342 } 343 344 // check size 345 if (size > sizeof(att_request_buffer)) return; 346 347 // last request still in processing? 348 if (att_server_state != ATT_SERVER_IDLE) return; 349 350 // store request 351 att_server_state = ATT_SERVER_REQUEST_RECEIVED; 352 att_request_size = size; 353 memcpy(att_request_buffer, packet, size); 354 355 att_run(); 356 } 357 358 void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){ 359 360 sm_register_packet_handler(att_event_packet_handler); 361 362 att_dispatch_register_server(att_packet_handler); 363 364 att_server_state = ATT_SERVER_IDLE; 365 att_set_db(db); 366 att_set_read_callback(read_callback); 367 att_set_write_callback(write_callback); 368 369 } 370 371 void att_server_register_packet_handler(btstack_packet_handler_t handler){ 372 att_client_packet_handler = handler; 373 } 374 375 int att_server_can_send(void){ 376 if (att_connection.con_handle == 0) return 0; 377 return l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle); 378 } 379 380 int att_server_notify(uint16_t handle, uint8_t *value, uint16_t value_len){ 381 if (!l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 382 383 l2cap_reserve_packet_buffer(); 384 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 385 uint16_t size = att_prepare_handle_value_notification(&att_connection, handle, value, value_len, packet_buffer); 386 return l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 387 } 388 389 int att_server_indicate(uint16_t handle, uint8_t *value, uint16_t value_len){ 390 if (att_handle_value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PORGRESS; 391 if (!l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 392 393 // track indication 394 att_handle_value_indication_handle = handle; 395 run_loop_set_timer_handler(&att_handle_value_indication_timer, att_handle_value_indication_timeout); 396 run_loop_set_timer(&att_handle_value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS); 397 run_loop_add_timer(&att_handle_value_indication_timer); 398 399 l2cap_reserve_packet_buffer(); 400 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 401 uint16_t size = att_prepare_handle_value_indication(&att_connection, handle, value, value_len, packet_buffer); 402 l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 403 return 0; 404 } 405