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 #define __BTSTACK_FILE__ "att_server.c" 39 40 41 // 42 // ATT Server Globals 43 // 44 45 #include <stdint.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <inttypes.h> 50 51 #include "btstack_config.h" 52 53 #include "att_dispatch.h" 54 #include "ble/att_db.h" 55 #include "ble/att_server.h" 56 #include "ble/core.h" 57 #include "ble/le_device_db.h" 58 #include "ble/sm.h" 59 #include "btstack_debug.h" 60 #include "btstack_event.h" 61 #include "btstack_memory.h" 62 #include "btstack_run_loop.h" 63 #include "gap.h" 64 #include "hci.h" 65 #include "hci_dump.h" 66 #include "l2cap.h" 67 68 static void att_run_for_context(att_server_t * att_server); 69 70 // global 71 static btstack_packet_callback_registration_t hci_event_callback_registration; 72 static btstack_packet_callback_registration_t sm_event_callback_registration; 73 static btstack_packet_handler_t att_client_packet_handler = NULL; 74 static btstack_linked_list_t can_send_now_clients; 75 static uint8_t att_client_waiting_for_can_send; 76 77 static att_server_t * att_server_for_handle(hci_con_handle_t con_handle){ 78 hci_connection_t * hci_connection = hci_connection_for_handle(con_handle); 79 if (!hci_connection) return NULL; 80 return &hci_connection->att_server; 81 } 82 83 #ifdef ENABLE_LE_SIGNED_WRITE 84 static att_server_t * att_server_for_state(att_server_state_t state){ 85 btstack_linked_list_iterator_t it; 86 hci_connections_get_iterator(&it); 87 while(btstack_linked_list_iterator_has_next(&it)){ 88 hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it); 89 att_server_t * att_server = &connection->att_server; 90 if (att_server->state == state) return att_server; 91 } 92 return NULL; 93 } 94 #endif 95 96 static void att_handle_value_indication_notify_client(uint8_t status, uint16_t client_handle, uint16_t attribute_handle){ 97 if (!att_client_packet_handler) return; 98 99 uint8_t event[7]; 100 int pos = 0; 101 event[pos++] = ATT_EVENT_HANDLE_VALUE_INDICATION_COMPLETE; 102 event[pos++] = sizeof(event) - 2; 103 event[pos++] = status; 104 little_endian_store_16(event, pos, client_handle); 105 pos += 2; 106 little_endian_store_16(event, pos, attribute_handle); 107 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 108 } 109 110 static void att_emit_mtu_event(hci_con_handle_t con_handle, uint16_t mtu){ 111 if (!att_client_packet_handler) return; 112 113 uint8_t event[6]; 114 int pos = 0; 115 event[pos++] = ATT_EVENT_MTU_EXCHANGE_COMPLETE; 116 event[pos++] = sizeof(event) - 2; 117 little_endian_store_16(event, pos, con_handle); 118 pos += 2; 119 little_endian_store_16(event, pos, mtu); 120 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 121 } 122 123 static void att_emit_can_send_now_event(void){ 124 if (!att_client_packet_handler) return; 125 126 uint8_t event[] = { ATT_EVENT_CAN_SEND_NOW, 0}; 127 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 128 } 129 130 static void att_handle_value_indication_timeout(btstack_timer_source_t *ts){ 131 hci_con_handle_t con_handle = (hci_con_handle_t) (uintptr_t) btstack_run_loop_get_timer_context(ts); 132 att_server_t * att_server = att_server_for_handle(con_handle); 133 if (!att_server) return; 134 uint16_t att_handle = att_server->value_indication_handle; 135 att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_server->connection.con_handle, att_handle); 136 } 137 138 static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ 139 140 UNUSED(channel); 141 UNUSED(size); 142 143 att_server_t * att_server; 144 hci_con_handle_t con_handle; 145 146 switch (packet_type) { 147 148 case HCI_EVENT_PACKET: 149 switch (hci_event_packet_get_type(packet)) { 150 151 case HCI_EVENT_LE_META: 152 switch (packet[2]) { 153 case HCI_SUBEVENT_LE_CONNECTION_COMPLETE: 154 con_handle = little_endian_read_16(packet, 4); 155 att_server = att_server_for_handle(con_handle); 156 if (!att_server) break; 157 // store connection info 158 att_server->peer_addr_type = packet[7]; 159 reverse_bd_addr(&packet[8], att_server->peer_address); 160 att_server->connection.con_handle = con_handle; 161 // reset connection properties 162 att_server->state = ATT_SERVER_IDLE; 163 att_server->connection.mtu = ATT_DEFAULT_MTU; 164 att_server->connection.max_mtu = l2cap_max_le_mtu(); 165 if (att_server->connection.max_mtu > ATT_REQUEST_BUFFER_SIZE){ 166 att_server->connection.max_mtu = ATT_REQUEST_BUFFER_SIZE; 167 } 168 att_server->connection.encryption_key_size = 0; 169 att_server->connection.authenticated = 0; 170 att_server->connection.authorized = 0; 171 att_server->ir_le_device_db_index = -1; 172 break; 173 174 default: 175 break; 176 } 177 break; 178 179 case HCI_EVENT_ENCRYPTION_CHANGE: 180 case HCI_EVENT_ENCRYPTION_KEY_REFRESH_COMPLETE: 181 // check handle 182 con_handle = little_endian_read_16(packet, 3); 183 att_server = att_server_for_handle(con_handle); 184 if (!att_server) break; 185 att_server->connection.encryption_key_size = sm_encryption_key_size(con_handle); 186 att_server->connection.authenticated = sm_authenticated(con_handle); 187 break; 188 189 case HCI_EVENT_DISCONNECTION_COMPLETE: 190 // check handle 191 con_handle = hci_event_disconnection_complete_get_connection_handle(packet); 192 att_server = att_server_for_handle(con_handle); 193 if (!att_server) break; 194 att_clear_transaction_queue(&att_server->connection); 195 att_server->connection.con_handle = 0; 196 att_server->value_indication_handle = 0; // reset error state 197 att_server->state = ATT_SERVER_IDLE; 198 break; 199 200 case SM_EVENT_IDENTITY_RESOLVING_STARTED: 201 con_handle = sm_event_identity_resolving_started_get_handle(packet); 202 att_server = att_server_for_handle(con_handle); 203 if (!att_server) break; 204 log_info("SM_EVENT_IDENTITY_RESOLVING_STARTED"); 205 att_server->ir_lookup_active = 1; 206 break; 207 case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED: 208 con_handle = sm_event_identity_resolving_succeeded_get_handle(packet); 209 att_server = att_server_for_handle(con_handle); 210 if (!att_server) break; 211 att_server->ir_lookup_active = 0; 212 att_server->ir_le_device_db_index = sm_event_identity_resolving_succeeded_get_index_internal(packet); 213 log_info("SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED id %u", att_server->ir_le_device_db_index); 214 att_run_for_context(att_server); 215 break; 216 case SM_EVENT_IDENTITY_RESOLVING_FAILED: 217 con_handle = sm_event_identity_resolving_failed_get_handle(packet); 218 att_server = att_server_for_handle(con_handle); 219 if (!att_server) break; 220 log_info("SM_EVENT_IDENTITY_RESOLVING_FAILED"); 221 att_server->ir_lookup_active = 0; 222 att_server->ir_le_device_db_index = -1; 223 att_run_for_context(att_server); 224 break; 225 case SM_EVENT_AUTHORIZATION_RESULT: { 226 con_handle = sm_event_authorization_result_get_handle(packet); 227 att_server = att_server_for_handle(con_handle); 228 if (!att_server) break; 229 att_server->connection.authorized = sm_event_authorization_result_get_authorization_result(packet); 230 att_dispatch_server_request_can_send_now_event(con_handle); 231 break; 232 } 233 default: 234 break; 235 } 236 break; 237 default: 238 break; 239 } 240 } 241 242 #ifdef ENABLE_LE_SIGNED_WRITE 243 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){ 244 245 att_server_t * att_server = att_server_for_state(ATT_SERVER_W4_SIGNED_WRITE_VALIDATION); 246 if (!att_server) return; 247 248 uint8_t hash_flipped[8]; 249 reverse_64(hash, hash_flipped); 250 if (memcmp(hash_flipped, &att_server->request_buffer[att_server->request_size-8], 8)){ 251 log_info("ATT Signed Write, invalid signature"); 252 att_server->state = ATT_SERVER_IDLE; 253 return; 254 } 255 log_info("ATT Signed Write, valid signature"); 256 257 // update sequence number 258 uint32_t counter_packet = little_endian_read_32(att_server->request_buffer, att_server->request_size-12); 259 le_device_db_remote_counter_set(att_server->ir_le_device_db_index, counter_packet+1); 260 att_server->state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 261 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 262 } 263 #endif 264 265 // pre: att_server->state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED 266 // pre: can send now 267 // returns: 1 if packet was sent 268 static int att_server_process_validated_request(att_server_t * att_server){ 269 270 l2cap_reserve_packet_buffer(); 271 uint8_t * att_response_buffer = l2cap_get_outgoing_buffer(); 272 uint16_t att_response_size = att_handle_request(&att_server->connection, att_server->request_buffer, att_server->request_size, att_response_buffer); 273 274 // intercept "insufficient authorization" for authenticated connections to allow for user authorization 275 if ((att_response_size >= 4) 276 && (att_response_buffer[0] == ATT_ERROR_RESPONSE) 277 && (att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION) 278 && (att_server->connection.authenticated)){ 279 280 switch (sm_authorization_state(att_server->connection.con_handle)){ 281 case AUTHORIZATION_UNKNOWN: 282 l2cap_release_packet_buffer(); 283 sm_request_pairing(att_server->connection.con_handle); 284 return 0; 285 case AUTHORIZATION_PENDING: 286 l2cap_release_packet_buffer(); 287 return 0; 288 default: 289 break; 290 } 291 } 292 293 att_server->state = ATT_SERVER_IDLE; 294 if (att_response_size == 0) { 295 l2cap_release_packet_buffer(); 296 return 0; 297 } 298 299 l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_size); 300 301 // notify client about MTU exchange result 302 if (att_response_buffer[0] == ATT_EXCHANGE_MTU_RESPONSE){ 303 att_emit_mtu_event(att_server->connection.con_handle, att_server->connection.mtu); 304 } 305 return 1; 306 } 307 308 static void att_run_for_context(att_server_t * att_server){ 309 switch (att_server->state){ 310 case ATT_SERVER_REQUEST_RECEIVED: 311 #ifdef ENABLE_LE_SIGNED_WRITE 312 if (att_server->request_buffer[0] == ATT_SIGNED_WRITE_COMMAND){ 313 log_info("ATT Signed Write!"); 314 if (!sm_cmac_ready()) { 315 log_info("ATT Signed Write, sm_cmac engine not ready. Abort"); 316 att_server->state = ATT_SERVER_IDLE; 317 return; 318 } 319 if (att_server->request_size < (3 + 12)) { 320 log_info("ATT Signed Write, request to short. Abort."); 321 att_server->state = ATT_SERVER_IDLE; 322 return; 323 } 324 if (att_server->ir_lookup_active){ 325 return; 326 } 327 if (att_server->ir_le_device_db_index < 0){ 328 log_info("ATT Signed Write, CSRK not available"); 329 att_server->state = ATT_SERVER_IDLE; 330 return; 331 } 332 333 // check counter 334 uint32_t counter_packet = little_endian_read_32(att_server->request_buffer, att_server->request_size-12); 335 uint32_t counter_db = le_device_db_remote_counter_get(att_server->ir_le_device_db_index); 336 log_info("ATT Signed Write, DB counter %"PRIu32", packet counter %"PRIu32, counter_db, counter_packet); 337 if (counter_packet < counter_db){ 338 log_info("ATT Signed Write, db reports higher counter, abort"); 339 att_server->state = ATT_SERVER_IDLE; 340 return; 341 } 342 343 // signature is { sequence counter, secure hash } 344 sm_key_t csrk; 345 le_device_db_remote_csrk_get(att_server->ir_le_device_db_index, csrk); 346 att_server->state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION; 347 log_info("Orig Signature: "); 348 log_info_hexdump( &att_server->request_buffer[att_server->request_size-8], 8); 349 uint16_t attribute_handle = little_endian_read_16(att_server->request_buffer, 1); 350 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); 351 return; 352 } 353 #endif 354 // move on 355 att_server->state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 356 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 357 break; 358 359 default: 360 break; 361 } 362 } 363 364 static void att_server_handle_can_send_now(void){ 365 366 // NOTE: we get l2cap fixed channel instead of con_handle 367 368 btstack_linked_list_iterator_t it; 369 hci_connections_get_iterator(&it); 370 while(btstack_linked_list_iterator_has_next(&it)){ 371 hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it); 372 att_server_t * att_server = &connection->att_server; 373 if (att_server->state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED){ 374 int sent = att_server_process_validated_request(att_server); 375 if (sent && (att_client_waiting_for_can_send || !btstack_linked_list_empty(&can_send_now_clients))){ 376 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 377 return; 378 } 379 } 380 } 381 382 while (!btstack_linked_list_empty(&can_send_now_clients)){ 383 // handle first client 384 btstack_context_callback_registration_t * client = (btstack_context_callback_registration_t*) can_send_now_clients; 385 hci_con_handle_t con_handle = (uintptr_t) client->context; 386 btstack_linked_list_remove(&can_send_now_clients, (btstack_linked_item_t *) client); 387 client->callback(client->context); 388 389 // request again if needed 390 if (!att_dispatch_server_can_send_now(con_handle)){ 391 if (!btstack_linked_list_empty(&can_send_now_clients) || att_client_waiting_for_can_send){ 392 att_dispatch_server_request_can_send_now_event(con_handle); 393 } 394 return; 395 } 396 } 397 398 if (att_client_waiting_for_can_send){ 399 att_client_waiting_for_can_send = 0; 400 att_emit_can_send_now_event(); 401 } 402 } 403 404 static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ 405 406 att_server_t * att_server; 407 408 switch (packet_type){ 409 410 case HCI_EVENT_PACKET: 411 if (packet[0] != L2CAP_EVENT_CAN_SEND_NOW) break; 412 att_server_handle_can_send_now(); 413 break; 414 415 case ATT_DATA_PACKET: 416 log_info("ATT Packet, handle 0x%04x", handle); 417 att_server = att_server_for_handle(handle); 418 if (!att_server) break; 419 420 // handle value indication confirms 421 if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_server->value_indication_handle){ 422 btstack_run_loop_remove_timer(&att_server->value_indication_timer); 423 uint16_t att_handle = att_server->value_indication_handle; 424 att_server->value_indication_handle = 0; 425 att_handle_value_indication_notify_client(0, att_server->connection.con_handle, att_handle); 426 return; 427 } 428 429 // directly process command 430 // note: signed write cannot be handled directly as authentication needs to be verified 431 if (packet[0] == ATT_WRITE_COMMAND){ 432 att_handle_request(&att_server->connection, packet, size, 0); 433 return; 434 } 435 436 // check size 437 if (size > sizeof(att_server->request_buffer)) { 438 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)); 439 return; 440 } 441 442 // last request still in processing? 443 if (att_server->state != ATT_SERVER_IDLE){ 444 log_info("att_packet_handler: skipping att pdu 0x%02x as server not idle (state %u)", packet[0], att_server->state); 445 return; 446 } 447 448 // store request 449 att_server->state = ATT_SERVER_REQUEST_RECEIVED; 450 att_server->request_size = size; 451 memcpy(att_server->request_buffer, packet, size); 452 453 att_run_for_context(att_server); 454 break; 455 } 456 } 457 458 void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){ 459 460 // register for HCI Events 461 hci_event_callback_registration.callback = &att_event_packet_handler; 462 hci_add_event_handler(&hci_event_callback_registration); 463 464 // register for SM events 465 sm_event_callback_registration.callback = &att_event_packet_handler; 466 sm_add_event_handler(&sm_event_callback_registration); 467 468 // and L2CAP ATT Server PDUs 469 att_dispatch_register_server(att_packet_handler); 470 471 att_set_db(db); 472 att_set_read_callback(read_callback); 473 att_set_write_callback(write_callback); 474 475 } 476 477 void att_server_register_packet_handler(btstack_packet_handler_t handler){ 478 att_client_packet_handler = handler; 479 } 480 481 int att_server_can_send_packet_now(hci_con_handle_t con_handle){ 482 return att_dispatch_server_can_send_now(con_handle); 483 } 484 485 void att_server_request_can_send_now_event(hci_con_handle_t con_handle){ 486 log_debug("att_server_request_can_send_now_event 0x%04x", con_handle); 487 att_client_waiting_for_can_send = 1; 488 att_dispatch_server_request_can_send_now_event(con_handle); 489 } 490 491 void att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){ 492 // check if can send already 493 if (att_dispatch_server_can_send_now(con_handle)){ 494 callback_registration->callback(callback_registration->context); 495 return; 496 } 497 callback_registration->context = (void*)(uintptr_t) con_handle; 498 btstack_linked_list_add_tail(&can_send_now_clients, (btstack_linked_item_t*) callback_registration); 499 att_dispatch_server_request_can_send_now_event(con_handle); 500 } 501 502 503 int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 504 att_server_t * att_server = att_server_for_handle(con_handle); 505 if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER; 506 507 if (!att_dispatch_server_can_send_now(con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 508 509 l2cap_reserve_packet_buffer(); 510 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 511 uint16_t size = att_prepare_handle_value_notification(&att_server->connection, attribute_handle, value, value_len, packet_buffer); 512 return l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 513 } 514 515 int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 516 att_server_t * att_server = att_server_for_handle(con_handle); 517 if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER; 518 519 if (att_server->value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PROGRESS; 520 if (!att_dispatch_server_can_send_now(con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 521 522 // track indication 523 att_server->value_indication_handle = attribute_handle; 524 btstack_run_loop_set_timer_handler(&att_server->value_indication_timer, att_handle_value_indication_timeout); 525 btstack_run_loop_set_timer(&att_server->value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS); 526 btstack_run_loop_add_timer(&att_server->value_indication_timer); 527 528 l2cap_reserve_packet_buffer(); 529 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 530 uint16_t size = att_prepare_handle_value_indication(&att_server->connection, attribute_handle, value, value_len, packet_buffer); 531 l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 532 return 0; 533 } 534