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 "att_dispatch.h" 52 #include "ble/att_db.h" 53 #include "ble/att_server.h" 54 #include "ble/core.h" 55 #include "ble/le_device_db.h" 56 #include "ble/sm.h" 57 #include "btstack_debug.h" 58 #include "btstack_event.h" 59 #include "btstack_memory.h" 60 #include "btstack_run_loop.h" 61 #include "gap.h" 62 #include "hci.h" 63 #include "hci_dump.h" 64 #include "l2cap.h" 65 66 static void att_run_for_context(att_server_t * att_server); 67 68 // global 69 static btstack_packet_callback_registration_t hci_event_callback_registration; 70 static btstack_packet_callback_registration_t sm_event_callback_registration; 71 static btstack_packet_handler_t att_client_packet_handler = NULL; 72 static btstack_linked_list_t can_send_now_clients; 73 static uint8_t att_client_waiting_for_can_send; 74 75 static att_server_t * att_server_for_handle(hci_con_handle_t con_handle){ 76 hci_connection_t * hci_connection = hci_connection_for_handle(con_handle); 77 if (!hci_connection) return NULL; 78 return &hci_connection->att_server; 79 } 80 81 #ifdef ENABLE_LE_SIGNED_WRITE 82 static att_server_t * att_server_for_state(att_server_state_t state){ 83 btstack_linked_list_iterator_t it; 84 hci_connections_get_iterator(&it); 85 while(btstack_linked_list_iterator_has_next(&it)){ 86 hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it); 87 att_server_t * att_server = &connection->att_server; 88 if (att_server->state == state) return att_server; 89 } 90 return NULL; 91 } 92 #endif 93 94 static void att_handle_value_indication_notify_client(uint8_t status, uint16_t client_handle, uint16_t attribute_handle){ 95 if (!att_client_packet_handler) return; 96 97 uint8_t event[7]; 98 int pos = 0; 99 event[pos++] = ATT_EVENT_HANDLE_VALUE_INDICATION_COMPLETE; 100 event[pos++] = sizeof(event) - 2; 101 event[pos++] = status; 102 little_endian_store_16(event, pos, client_handle); 103 pos += 2; 104 little_endian_store_16(event, pos, attribute_handle); 105 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 106 } 107 108 static void att_emit_mtu_event(hci_con_handle_t con_handle, uint16_t mtu){ 109 if (!att_client_packet_handler) return; 110 111 uint8_t event[6]; 112 int pos = 0; 113 event[pos++] = ATT_EVENT_MTU_EXCHANGE_COMPLETE; 114 event[pos++] = sizeof(event) - 2; 115 little_endian_store_16(event, pos, con_handle); 116 pos += 2; 117 little_endian_store_16(event, pos, mtu); 118 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 119 } 120 121 static void att_emit_can_send_now_event(void){ 122 if (!att_client_packet_handler) return; 123 124 uint8_t event[] = { ATT_EVENT_CAN_SEND_NOW, 0}; 125 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 126 } 127 128 static void att_handle_value_indication_timeout(btstack_timer_source_t *ts){ 129 hci_con_handle_t con_handle = (hci_con_handle_t) (uintptr_t) btstack_run_loop_get_timer_context(ts); 130 att_server_t * att_server = att_server_for_handle(con_handle); 131 if (!att_server) return; 132 uint16_t att_handle = att_server->value_indication_handle; 133 att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_server->connection.con_handle, att_handle); 134 } 135 136 static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ 137 138 UNUSED(channel); 139 UNUSED(size); 140 141 att_server_t * att_server; 142 hci_con_handle_t con_handle; 143 144 switch (packet_type) { 145 146 case HCI_EVENT_PACKET: 147 switch (hci_event_packet_get_type(packet)) { 148 149 case HCI_EVENT_LE_META: 150 switch (packet[2]) { 151 case HCI_SUBEVENT_LE_CONNECTION_COMPLETE: 152 con_handle = little_endian_read_16(packet, 4); 153 att_server = att_server_for_handle(con_handle); 154 if (!att_server) break; 155 // store connection info 156 att_server->peer_addr_type = packet[7]; 157 reverse_bd_addr(&packet[8], att_server->peer_address); 158 att_server->connection.con_handle = con_handle; 159 // reset connection properties 160 att_server->state = ATT_SERVER_IDLE; 161 att_server->connection.mtu = ATT_DEFAULT_MTU; 162 att_server->connection.max_mtu = l2cap_max_le_mtu(); 163 if (att_server->connection.max_mtu > ATT_REQUEST_BUFFER_SIZE){ 164 att_server->connection.max_mtu = ATT_REQUEST_BUFFER_SIZE; 165 } 166 att_server->connection.encryption_key_size = 0; 167 att_server->connection.authenticated = 0; 168 att_server->connection.authorized = 0; 169 att_server->ir_le_device_db_index = -1; 170 break; 171 172 default: 173 break; 174 } 175 break; 176 177 case HCI_EVENT_ENCRYPTION_CHANGE: 178 case HCI_EVENT_ENCRYPTION_KEY_REFRESH_COMPLETE: 179 // check handle 180 con_handle = little_endian_read_16(packet, 3); 181 att_server = att_server_for_handle(con_handle); 182 if (!att_server) break; 183 att_server->connection.encryption_key_size = sm_encryption_key_size(con_handle); 184 att_server->connection.authenticated = sm_authenticated(con_handle); 185 break; 186 187 case HCI_EVENT_DISCONNECTION_COMPLETE: 188 // check handle 189 con_handle = hci_event_disconnection_complete_get_connection_handle(packet); 190 att_server = att_server_for_handle(con_handle); 191 if (!att_server) break; 192 att_clear_transaction_queue(&att_server->connection); 193 att_server->connection.con_handle = 0; 194 att_server->value_indication_handle = 0; // reset error state 195 att_server->state = ATT_SERVER_IDLE; 196 break; 197 198 case SM_EVENT_IDENTITY_RESOLVING_STARTED: 199 con_handle = sm_event_identity_resolving_started_get_handle(packet); 200 att_server = att_server_for_handle(con_handle); 201 if (!att_server) break; 202 log_info("SM_EVENT_IDENTITY_RESOLVING_STARTED"); 203 att_server->ir_lookup_active = 1; 204 break; 205 case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED: 206 con_handle = sm_event_identity_resolving_succeeded_get_handle(packet); 207 att_server = att_server_for_handle(con_handle); 208 if (!att_server) break; 209 att_server->ir_lookup_active = 0; 210 att_server->ir_le_device_db_index = sm_event_identity_resolving_succeeded_get_index_internal(packet); 211 log_info("SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED id %u", att_server->ir_le_device_db_index); 212 att_run_for_context(att_server); 213 break; 214 case SM_EVENT_IDENTITY_RESOLVING_FAILED: 215 con_handle = sm_event_identity_resolving_failed_get_handle(packet); 216 att_server = att_server_for_handle(con_handle); 217 if (!att_server) break; 218 log_info("SM_EVENT_IDENTITY_RESOLVING_FAILED"); 219 att_server->ir_lookup_active = 0; 220 att_server->ir_le_device_db_index = -1; 221 att_run_for_context(att_server); 222 break; 223 case SM_EVENT_AUTHORIZATION_RESULT: { 224 con_handle = sm_event_authorization_result_get_handle(packet); 225 att_server = att_server_for_handle(con_handle); 226 if (!att_server) break; 227 att_server->connection.authorized = sm_event_authorization_result_get_authorization_result(packet); 228 att_dispatch_server_request_can_send_now_event(con_handle); 229 break; 230 } 231 default: 232 break; 233 } 234 break; 235 default: 236 break; 237 } 238 } 239 240 #ifdef ENABLE_LE_SIGNED_WRITE 241 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){ 242 243 att_server_t * att_server = att_server_for_state(ATT_SERVER_W4_SIGNED_WRITE_VALIDATION); 244 if (!att_server) return; 245 246 uint8_t hash_flipped[8]; 247 reverse_64(hash, hash_flipped); 248 if (memcmp(hash_flipped, &att_server->request_buffer[att_server->request_size-8], 8)){ 249 log_info("ATT Signed Write, invalid signature"); 250 att_server->state = ATT_SERVER_IDLE; 251 return; 252 } 253 log_info("ATT Signed Write, valid signature"); 254 255 // update sequence number 256 uint32_t counter_packet = little_endian_read_32(att_server->request_buffer, att_server->request_size-12); 257 le_device_db_remote_counter_set(att_server->ir_le_device_db_index, counter_packet+1); 258 att_server->state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 259 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 260 } 261 #endif 262 263 // pre: att_server->state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED 264 // pre: can send now 265 // returns: 1 if packet was sent 266 static int att_server_process_validated_request(att_server_t * att_server){ 267 268 l2cap_reserve_packet_buffer(); 269 uint8_t * att_response_buffer = l2cap_get_outgoing_buffer(); 270 uint16_t att_response_size = att_handle_request(&att_server->connection, att_server->request_buffer, att_server->request_size, att_response_buffer); 271 272 // intercept "insufficient authorization" for authenticated connections to allow for user authorization 273 if ((att_response_size >= 4) 274 && (att_response_buffer[0] == ATT_ERROR_RESPONSE) 275 && (att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION) 276 && (att_server->connection.authenticated)){ 277 278 switch (sm_authorization_state(att_server->connection.con_handle)){ 279 case AUTHORIZATION_UNKNOWN: 280 l2cap_release_packet_buffer(); 281 sm_request_pairing(att_server->connection.con_handle); 282 return 0; 283 case AUTHORIZATION_PENDING: 284 l2cap_release_packet_buffer(); 285 return 0; 286 default: 287 break; 288 } 289 } 290 291 att_server->state = ATT_SERVER_IDLE; 292 if (att_response_size == 0) { 293 l2cap_release_packet_buffer(); 294 return 0; 295 } 296 297 l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_size); 298 299 // notify client about MTU exchange result 300 if (att_response_buffer[0] == ATT_EXCHANGE_MTU_RESPONSE){ 301 att_emit_mtu_event(att_server->connection.con_handle, att_server->connection.mtu); 302 } 303 return 1; 304 } 305 306 static void att_run_for_context(att_server_t * att_server){ 307 switch (att_server->state){ 308 case ATT_SERVER_REQUEST_RECEIVED: 309 #ifdef ENABLE_LE_SIGNED_WRITE 310 if (att_server->request_buffer[0] == ATT_SIGNED_WRITE_COMMAND){ 311 log_info("ATT Signed Write!"); 312 if (!sm_cmac_ready()) { 313 log_info("ATT Signed Write, sm_cmac engine not ready. Abort"); 314 att_server->state = ATT_SERVER_IDLE; 315 return; 316 } 317 if (att_server->request_size < (3 + 12)) { 318 log_info("ATT Signed Write, request to short. Abort."); 319 att_server->state = ATT_SERVER_IDLE; 320 return; 321 } 322 if (att_server->ir_lookup_active){ 323 return; 324 } 325 if (att_server->ir_le_device_db_index < 0){ 326 log_info("ATT Signed Write, CSRK not available"); 327 att_server->state = ATT_SERVER_IDLE; 328 return; 329 } 330 331 // check counter 332 uint32_t counter_packet = little_endian_read_32(att_server->request_buffer, att_server->request_size-12); 333 uint32_t counter_db = le_device_db_remote_counter_get(att_server->ir_le_device_db_index); 334 log_info("ATT Signed Write, DB counter %"PRIu32", packet counter %"PRIu32, counter_db, counter_packet); 335 if (counter_packet < counter_db){ 336 log_info("ATT Signed Write, db reports higher counter, abort"); 337 att_server->state = ATT_SERVER_IDLE; 338 return; 339 } 340 341 // signature is { sequence counter, secure hash } 342 sm_key_t csrk; 343 le_device_db_remote_csrk_get(att_server->ir_le_device_db_index, csrk); 344 att_server->state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION; 345 log_info("Orig Signature: "); 346 log_info_hexdump( &att_server->request_buffer[att_server->request_size-8], 8); 347 uint16_t attribute_handle = little_endian_read_16(att_server->request_buffer, 1); 348 sm_cmac_signed_write_start(csrk, att_server->request_buffer[0], attribute_handle, att_server->request_size - 15, &att_server->request_buffer[3], counter_packet, att_signed_write_handle_cmac_result); 349 return; 350 } 351 #endif 352 // move on 353 att_server->state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 354 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 355 break; 356 357 default: 358 break; 359 } 360 } 361 362 static void att_server_handle_can_send_now(void){ 363 364 // NOTE: we get l2cap fixed channel instead of con_handle 365 366 btstack_linked_list_iterator_t it; 367 hci_connections_get_iterator(&it); 368 while(btstack_linked_list_iterator_has_next(&it)){ 369 hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it); 370 att_server_t * att_server = &connection->att_server; 371 if (att_server->state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED){ 372 int sent = att_server_process_validated_request(att_server); 373 if (sent && (att_client_waiting_for_can_send || !btstack_linked_list_empty(&can_send_now_clients))){ 374 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 375 return; 376 } 377 } 378 } 379 380 while (!btstack_linked_list_empty(&can_send_now_clients)){ 381 // handle first client 382 btstack_context_callback_registration_t * client = (btstack_context_callback_registration_t*) can_send_now_clients; 383 hci_con_handle_t con_handle = (uintptr_t) client->context; 384 btstack_linked_list_remove(&can_send_now_clients, (btstack_linked_item_t *) client); 385 client->callback(client->context); 386 387 // request again if needed 388 if (!att_dispatch_server_can_send_now(con_handle)){ 389 if (!btstack_linked_list_empty(&can_send_now_clients) || att_client_waiting_for_can_send){ 390 att_dispatch_server_request_can_send_now_event(con_handle); 391 } 392 return; 393 } 394 } 395 396 if (att_client_waiting_for_can_send){ 397 att_client_waiting_for_can_send = 0; 398 att_emit_can_send_now_event(); 399 } 400 } 401 402 static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ 403 404 att_server_t * att_server; 405 406 switch (packet_type){ 407 408 case HCI_EVENT_PACKET: 409 if (packet[0] != L2CAP_EVENT_CAN_SEND_NOW) break; 410 att_server_handle_can_send_now(); 411 break; 412 413 case ATT_DATA_PACKET: 414 log_info("ATT Packet, handle 0x%04x", handle); 415 att_server = att_server_for_handle(handle); 416 if (!att_server) break; 417 418 // handle value indication confirms 419 if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_server->value_indication_handle){ 420 btstack_run_loop_remove_timer(&att_server->value_indication_timer); 421 uint16_t att_handle = att_server->value_indication_handle; 422 att_server->value_indication_handle = 0; 423 att_handle_value_indication_notify_client(0, att_server->connection.con_handle, att_handle); 424 return; 425 } 426 427 // directly process command 428 // note: signed write cannot be handled directly as authentication needs to be verified 429 if (packet[0] == ATT_WRITE_COMMAND){ 430 att_handle_request(&att_server->connection, packet, size, 0); 431 return; 432 } 433 434 // check size 435 if (size > sizeof(att_server->request_buffer)) { 436 log_info("att_packet_handler: dropping att pdu 0x%02x as size %u > att_server->request_buffer %u", packet[0], size, (int) sizeof(att_server->request_buffer)); 437 return; 438 } 439 440 // last request still in processing? 441 if (att_server->state != ATT_SERVER_IDLE){ 442 log_info("att_packet_handler: skipping att pdu 0x%02x as server not idle (state %u)", packet[0], att_server->state); 443 return; 444 } 445 446 // store request 447 att_server->state = ATT_SERVER_REQUEST_RECEIVED; 448 att_server->request_size = size; 449 memcpy(att_server->request_buffer, packet, size); 450 451 att_run_for_context(att_server); 452 break; 453 } 454 } 455 456 void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){ 457 458 // register for HCI Events 459 hci_event_callback_registration.callback = &att_event_packet_handler; 460 hci_add_event_handler(&hci_event_callback_registration); 461 462 // register for SM events 463 sm_event_callback_registration.callback = &att_event_packet_handler; 464 sm_add_event_handler(&sm_event_callback_registration); 465 466 // and L2CAP ATT Server PDUs 467 att_dispatch_register_server(att_packet_handler); 468 469 att_set_db(db); 470 att_set_read_callback(read_callback); 471 att_set_write_callback(write_callback); 472 473 } 474 475 void att_server_register_packet_handler(btstack_packet_handler_t handler){ 476 att_client_packet_handler = handler; 477 } 478 479 int att_server_can_send_packet_now(hci_con_handle_t con_handle){ 480 return att_dispatch_server_can_send_now(con_handle); 481 } 482 483 void att_server_request_can_send_now_event(hci_con_handle_t con_handle){ 484 log_debug("att_server_request_can_send_now_event 0x%04x", con_handle); 485 att_client_waiting_for_can_send = 1; 486 att_dispatch_server_request_can_send_now_event(con_handle); 487 } 488 489 void att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){ 490 // check if can send already 491 if (att_dispatch_server_can_send_now(con_handle)){ 492 callback_registration->callback(callback_registration->context); 493 return; 494 } 495 callback_registration->context = (void*)(uintptr_t) con_handle; 496 btstack_linked_list_add_tail(&can_send_now_clients, (btstack_linked_item_t*) callback_registration); 497 att_dispatch_server_request_can_send_now_event(con_handle); 498 } 499 500 501 int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 502 att_server_t * att_server = att_server_for_handle(con_handle); 503 if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER; 504 505 if (!att_dispatch_server_can_send_now(con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 506 507 l2cap_reserve_packet_buffer(); 508 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 509 uint16_t size = att_prepare_handle_value_notification(&att_server->connection, attribute_handle, value, value_len, packet_buffer); 510 return l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 511 } 512 513 int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 514 att_server_t * att_server = att_server_for_handle(con_handle); 515 if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER; 516 517 if (att_server->value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PORGRESS; 518 if (!att_dispatch_server_can_send_now(con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 519 520 // track indication 521 att_server->value_indication_handle = attribute_handle; 522 btstack_run_loop_set_timer_handler(&att_server->value_indication_timer, att_handle_value_indication_timeout); 523 btstack_run_loop_set_timer(&att_server->value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS); 524 btstack_run_loop_add_timer(&att_server->value_indication_timer); 525 526 l2cap_reserve_packet_buffer(); 527 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 528 uint16_t size = att_prepare_handle_value_indication(&att_server->connection, attribute_handle, value, value_len, packet_buffer); 529 l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 530 return 0; 531 } 532