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 void * context = btstack_run_loop_get_timer_context(ts); 132 hci_con_handle_t con_handle = (hci_con_handle_t) (uintptr_t) context; 133 att_server_t * att_server = att_server_for_handle(con_handle); 134 if (!att_server) return; 135 uint16_t att_handle = att_server->value_indication_handle; 136 att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_server->connection.con_handle, att_handle); 137 } 138 139 static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ 140 141 UNUSED(channel); 142 UNUSED(size); 143 144 att_server_t * att_server; 145 hci_con_handle_t con_handle; 146 147 switch (packet_type) { 148 149 case HCI_EVENT_PACKET: 150 switch (hci_event_packet_get_type(packet)) { 151 152 case HCI_EVENT_LE_META: 153 switch (packet[2]) { 154 case HCI_SUBEVENT_LE_CONNECTION_COMPLETE: 155 con_handle = little_endian_read_16(packet, 4); 156 att_server = att_server_for_handle(con_handle); 157 if (!att_server) break; 158 // store connection info 159 att_server->peer_addr_type = packet[7]; 160 reverse_bd_addr(&packet[8], att_server->peer_address); 161 att_server->connection.con_handle = con_handle; 162 // reset connection properties 163 att_server->state = ATT_SERVER_IDLE; 164 att_server->connection.mtu = ATT_DEFAULT_MTU; 165 att_server->connection.max_mtu = l2cap_max_le_mtu(); 166 if (att_server->connection.max_mtu > ATT_REQUEST_BUFFER_SIZE){ 167 att_server->connection.max_mtu = ATT_REQUEST_BUFFER_SIZE; 168 } 169 att_server->connection.encryption_key_size = 0; 170 att_server->connection.authenticated = 0; 171 att_server->connection.authorized = 0; 172 att_server->ir_le_device_db_index = -1; 173 break; 174 175 default: 176 break; 177 } 178 break; 179 180 case HCI_EVENT_ENCRYPTION_CHANGE: 181 case HCI_EVENT_ENCRYPTION_KEY_REFRESH_COMPLETE: 182 // check handle 183 con_handle = little_endian_read_16(packet, 3); 184 att_server = att_server_for_handle(con_handle); 185 if (!att_server) break; 186 att_server->connection.encryption_key_size = sm_encryption_key_size(con_handle); 187 att_server->connection.authenticated = sm_authenticated(con_handle); 188 break; 189 190 case HCI_EVENT_DISCONNECTION_COMPLETE: 191 // check handle 192 con_handle = hci_event_disconnection_complete_get_connection_handle(packet); 193 att_server = att_server_for_handle(con_handle); 194 if (!att_server) break; 195 att_clear_transaction_queue(&att_server->connection); 196 att_server->connection.con_handle = 0; 197 att_server->value_indication_handle = 0; // reset error state 198 att_server->state = ATT_SERVER_IDLE; 199 break; 200 201 case SM_EVENT_IDENTITY_RESOLVING_STARTED: 202 con_handle = sm_event_identity_resolving_started_get_handle(packet); 203 att_server = att_server_for_handle(con_handle); 204 if (!att_server) break; 205 log_info("SM_EVENT_IDENTITY_RESOLVING_STARTED"); 206 att_server->ir_lookup_active = 1; 207 break; 208 case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED: 209 con_handle = sm_event_identity_resolving_succeeded_get_handle(packet); 210 att_server = att_server_for_handle(con_handle); 211 if (!att_server) break; 212 att_server->ir_lookup_active = 0; 213 att_server->ir_le_device_db_index = sm_event_identity_resolving_succeeded_get_index_internal(packet); 214 log_info("SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED id %u", att_server->ir_le_device_db_index); 215 att_run_for_context(att_server); 216 break; 217 case SM_EVENT_IDENTITY_RESOLVING_FAILED: 218 con_handle = sm_event_identity_resolving_failed_get_handle(packet); 219 att_server = att_server_for_handle(con_handle); 220 if (!att_server) break; 221 log_info("SM_EVENT_IDENTITY_RESOLVING_FAILED"); 222 att_server->ir_lookup_active = 0; 223 att_server->ir_le_device_db_index = -1; 224 att_run_for_context(att_server); 225 break; 226 case SM_EVENT_AUTHORIZATION_RESULT: { 227 con_handle = sm_event_authorization_result_get_handle(packet); 228 att_server = att_server_for_handle(con_handle); 229 if (!att_server) break; 230 att_server->connection.authorized = sm_event_authorization_result_get_authorization_result(packet); 231 att_dispatch_server_request_can_send_now_event(con_handle); 232 break; 233 } 234 default: 235 break; 236 } 237 break; 238 default: 239 break; 240 } 241 } 242 243 #ifdef ENABLE_LE_SIGNED_WRITE 244 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){ 245 246 att_server_t * att_server = att_server_for_state(ATT_SERVER_W4_SIGNED_WRITE_VALIDATION); 247 if (!att_server) return; 248 249 uint8_t hash_flipped[8]; 250 reverse_64(hash, hash_flipped); 251 if (memcmp(hash_flipped, &att_server->request_buffer[att_server->request_size-8], 8)){ 252 log_info("ATT Signed Write, invalid signature"); 253 att_server->state = ATT_SERVER_IDLE; 254 return; 255 } 256 log_info("ATT Signed Write, valid signature"); 257 258 // update sequence number 259 uint32_t counter_packet = little_endian_read_32(att_server->request_buffer, att_server->request_size-12); 260 le_device_db_remote_counter_set(att_server->ir_le_device_db_index, counter_packet+1); 261 att_server->state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 262 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 263 } 264 #endif 265 266 // pre: att_server->state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED 267 // pre: can send now 268 // returns: 1 if packet was sent 269 static int att_server_process_validated_request(att_server_t * att_server){ 270 271 l2cap_reserve_packet_buffer(); 272 uint8_t * att_response_buffer = l2cap_get_outgoing_buffer(); 273 uint16_t att_response_size = att_handle_request(&att_server->connection, att_server->request_buffer, att_server->request_size, att_response_buffer); 274 275 // intercept "insufficient authorization" for authenticated connections to allow for user authorization 276 if ((att_response_size >= 4) 277 && (att_response_buffer[0] == ATT_ERROR_RESPONSE) 278 && (att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION) 279 && (att_server->connection.authenticated)){ 280 281 switch (sm_authorization_state(att_server->connection.con_handle)){ 282 case AUTHORIZATION_UNKNOWN: 283 l2cap_release_packet_buffer(); 284 sm_request_pairing(att_server->connection.con_handle); 285 return 0; 286 case AUTHORIZATION_PENDING: 287 l2cap_release_packet_buffer(); 288 return 0; 289 default: 290 break; 291 } 292 } 293 294 att_server->state = ATT_SERVER_IDLE; 295 if (att_response_size == 0) { 296 l2cap_release_packet_buffer(); 297 return 0; 298 } 299 300 l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_size); 301 302 // notify client about MTU exchange result 303 if (att_response_buffer[0] == ATT_EXCHANGE_MTU_RESPONSE){ 304 att_emit_mtu_event(att_server->connection.con_handle, att_server->connection.mtu); 305 } 306 return 1; 307 } 308 309 static void att_run_for_context(att_server_t * att_server){ 310 switch (att_server->state){ 311 case ATT_SERVER_REQUEST_RECEIVED: 312 #ifdef ENABLE_LE_SIGNED_WRITE 313 if (att_server->request_buffer[0] == ATT_SIGNED_WRITE_COMMAND){ 314 log_info("ATT Signed Write!"); 315 if (!sm_cmac_ready()) { 316 log_info("ATT Signed Write, sm_cmac engine not ready. Abort"); 317 att_server->state = ATT_SERVER_IDLE; 318 return; 319 } 320 if (att_server->request_size < (3 + 12)) { 321 log_info("ATT Signed Write, request to short. Abort."); 322 att_server->state = ATT_SERVER_IDLE; 323 return; 324 } 325 if (att_server->ir_lookup_active){ 326 return; 327 } 328 if (att_server->ir_le_device_db_index < 0){ 329 log_info("ATT Signed Write, CSRK not available"); 330 att_server->state = ATT_SERVER_IDLE; 331 return; 332 } 333 334 // check counter 335 uint32_t counter_packet = little_endian_read_32(att_server->request_buffer, att_server->request_size-12); 336 uint32_t counter_db = le_device_db_remote_counter_get(att_server->ir_le_device_db_index); 337 log_info("ATT Signed Write, DB counter %"PRIu32", packet counter %"PRIu32, counter_db, counter_packet); 338 if (counter_packet < counter_db){ 339 log_info("ATT Signed Write, db reports higher counter, abort"); 340 att_server->state = ATT_SERVER_IDLE; 341 return; 342 } 343 344 // signature is { sequence counter, secure hash } 345 sm_key_t csrk; 346 le_device_db_remote_csrk_get(att_server->ir_le_device_db_index, csrk); 347 att_server->state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION; 348 log_info("Orig Signature: "); 349 log_info_hexdump( &att_server->request_buffer[att_server->request_size-8], 8); 350 uint16_t attribute_handle = little_endian_read_16(att_server->request_buffer, 1); 351 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); 352 return; 353 } 354 #endif 355 // move on 356 att_server->state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 357 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 358 break; 359 360 default: 361 break; 362 } 363 } 364 365 static void att_server_handle_can_send_now(void){ 366 367 // NOTE: we get l2cap fixed channel instead of con_handle 368 369 btstack_linked_list_iterator_t it; 370 hci_connections_get_iterator(&it); 371 while(btstack_linked_list_iterator_has_next(&it)){ 372 hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it); 373 att_server_t * att_server = &connection->att_server; 374 if (att_server->state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED){ 375 int sent = att_server_process_validated_request(att_server); 376 if (sent && (att_client_waiting_for_can_send || !btstack_linked_list_empty(&can_send_now_clients))){ 377 att_dispatch_server_request_can_send_now_event(att_server->connection.con_handle); 378 return; 379 } 380 } 381 } 382 383 while (!btstack_linked_list_empty(&can_send_now_clients)){ 384 // handle first client 385 btstack_context_callback_registration_t * client = (btstack_context_callback_registration_t*) can_send_now_clients; 386 hci_con_handle_t con_handle = (uintptr_t) client->context; 387 btstack_linked_list_remove(&can_send_now_clients, (btstack_linked_item_t *) client); 388 client->callback(client->context); 389 390 // request again if needed 391 if (!att_dispatch_server_can_send_now(con_handle)){ 392 if (!btstack_linked_list_empty(&can_send_now_clients) || att_client_waiting_for_can_send){ 393 att_dispatch_server_request_can_send_now_event(con_handle); 394 } 395 return; 396 } 397 } 398 399 if (att_client_waiting_for_can_send){ 400 att_client_waiting_for_can_send = 0; 401 att_emit_can_send_now_event(); 402 } 403 } 404 405 static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ 406 407 att_server_t * att_server; 408 409 switch (packet_type){ 410 411 case HCI_EVENT_PACKET: 412 if (packet[0] != L2CAP_EVENT_CAN_SEND_NOW) break; 413 att_server_handle_can_send_now(); 414 break; 415 416 case ATT_DATA_PACKET: 417 log_info("ATT Packet, handle 0x%04x", handle); 418 att_server = att_server_for_handle(handle); 419 if (!att_server) break; 420 421 // handle value indication confirms 422 if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_server->value_indication_handle){ 423 btstack_run_loop_remove_timer(&att_server->value_indication_timer); 424 uint16_t att_handle = att_server->value_indication_handle; 425 att_server->value_indication_handle = 0; 426 att_handle_value_indication_notify_client(0, att_server->connection.con_handle, att_handle); 427 return; 428 } 429 430 // directly process command 431 // note: signed write cannot be handled directly as authentication needs to be verified 432 if (packet[0] == ATT_WRITE_COMMAND){ 433 att_handle_request(&att_server->connection, packet, size, 0); 434 return; 435 } 436 437 // check size 438 if (size > sizeof(att_server->request_buffer)) { 439 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)); 440 return; 441 } 442 443 // last request still in processing? 444 if (att_server->state != ATT_SERVER_IDLE){ 445 log_info("att_packet_handler: skipping att pdu 0x%02x as server not idle (state %u)", packet[0], att_server->state); 446 return; 447 } 448 449 // store request 450 att_server->state = ATT_SERVER_REQUEST_RECEIVED; 451 att_server->request_size = size; 452 memcpy(att_server->request_buffer, packet, size); 453 454 att_run_for_context(att_server); 455 break; 456 } 457 } 458 459 void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){ 460 461 // register for HCI Events 462 hci_event_callback_registration.callback = &att_event_packet_handler; 463 hci_add_event_handler(&hci_event_callback_registration); 464 465 // register for SM events 466 sm_event_callback_registration.callback = &att_event_packet_handler; 467 sm_add_event_handler(&sm_event_callback_registration); 468 469 // and L2CAP ATT Server PDUs 470 att_dispatch_register_server(att_packet_handler); 471 472 att_set_db(db); 473 att_set_read_callback(read_callback); 474 att_set_write_callback(write_callback); 475 476 } 477 478 void att_server_register_packet_handler(btstack_packet_handler_t handler){ 479 att_client_packet_handler = handler; 480 } 481 482 int att_server_can_send_packet_now(hci_con_handle_t con_handle){ 483 return att_dispatch_server_can_send_now(con_handle); 484 } 485 486 void att_server_request_can_send_now_event(hci_con_handle_t con_handle){ 487 log_debug("att_server_request_can_send_now_event 0x%04x", con_handle); 488 att_client_waiting_for_can_send = 1; 489 att_dispatch_server_request_can_send_now_event(con_handle); 490 } 491 492 void att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){ 493 // check if can send already 494 if (att_dispatch_server_can_send_now(con_handle)){ 495 callback_registration->callback(callback_registration->context); 496 return; 497 } 498 callback_registration->context = (void*)(uintptr_t) con_handle; 499 btstack_linked_list_add_tail(&can_send_now_clients, (btstack_linked_item_t*) callback_registration); 500 att_dispatch_server_request_can_send_now_event(con_handle); 501 } 502 503 504 int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 505 att_server_t * att_server = att_server_for_handle(con_handle); 506 if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER; 507 508 if (!att_dispatch_server_can_send_now(con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 509 510 l2cap_reserve_packet_buffer(); 511 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 512 uint16_t size = att_prepare_handle_value_notification(&att_server->connection, attribute_handle, value, value_len, packet_buffer); 513 return l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 514 } 515 516 int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 517 att_server_t * att_server = att_server_for_handle(con_handle); 518 if (!att_server) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER; 519 520 if (att_server->value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PROGRESS; 521 if (!att_dispatch_server_can_send_now(con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 522 523 // track indication 524 att_server->value_indication_handle = attribute_handle; 525 btstack_run_loop_set_timer_handler(&att_server->value_indication_timer, att_handle_value_indication_timeout); 526 btstack_run_loop_set_timer(&att_server->value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS); 527 btstack_run_loop_add_timer(&att_server->value_indication_timer); 528 529 l2cap_reserve_packet_buffer(); 530 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 531 uint16_t size = att_prepare_handle_value_indication(&att_server->connection, attribute_handle, value, value_len, packet_buffer); 532 l2cap_send_prepared_connectionless(att_server->connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 533 return 0; 534 } 535