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(void); 67 68 // max ATT request matches L2CAP PDU -- allow to use smaller buffer 69 #ifndef ATT_REQUEST_BUFFER_SIZE 70 #define ATT_REQUEST_BUFFER_SIZE HCI_ACL_PAYLOAD_SIZE 71 #endif 72 73 typedef enum { 74 ATT_SERVER_IDLE, 75 ATT_SERVER_REQUEST_RECEIVED, 76 ATT_SERVER_W4_SIGNED_WRITE_VALIDATION, 77 ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED, 78 } att_server_state_t; 79 80 static att_connection_t att_connection; 81 static att_server_state_t att_server_state; 82 83 static uint8_t att_client_addr_type; 84 static bd_addr_t att_client_address; 85 static uint8_t att_client_waiting_for_can_send; 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 btstack_timer_source_t att_handle_value_indication_timer; 94 static btstack_packet_callback_registration_t hci_event_callback_registration; 95 static btstack_packet_callback_registration_t sm_event_callback_registration; 96 static btstack_packet_handler_t att_client_packet_handler = NULL; 97 98 static void att_handle_value_indication_notify_client(uint8_t status, uint16_t client_handle, uint16_t attribute_handle){ 99 if (!att_client_packet_handler) return; 100 101 uint8_t event[7]; 102 int pos = 0; 103 event[pos++] = ATT_EVENT_HANDLE_VALUE_INDICATION_COMPLETE; 104 event[pos++] = sizeof(event) - 2; 105 event[pos++] = status; 106 little_endian_store_16(event, pos, client_handle); 107 pos += 2; 108 little_endian_store_16(event, pos, attribute_handle); 109 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 110 } 111 112 static void att_emit_mtu_event(hci_con_handle_t con_handle, uint16_t mtu){ 113 if (!att_client_packet_handler) return; 114 115 uint8_t event[6]; 116 int pos = 0; 117 event[pos++] = ATT_EVENT_MTU_EXCHANGE_COMPLETE; 118 event[pos++] = sizeof(event) - 2; 119 little_endian_store_16(event, pos, con_handle); 120 pos += 2; 121 little_endian_store_16(event, pos, mtu); 122 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 123 } 124 125 static void att_emit_can_send_now_event(void){ 126 if (!att_client_packet_handler) return; 127 128 uint8_t event[] = { ATT_EVENT_CAN_SEND_NOW, 0}; 129 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 130 } 131 132 static void att_handle_value_indication_timeout(btstack_timer_source_t *ts){ 133 uint16_t att_handle = att_handle_value_indication_handle; 134 att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_connection.con_handle, att_handle); 135 } 136 137 static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ 138 139 bd_addr_t event_address; 140 switch (packet_type) { 141 142 case HCI_EVENT_PACKET: 143 switch (hci_event_packet_get_type(packet)) { 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 reverse_bd_addr(&packet[8], att_client_address); 151 // reset connection properties 152 att_connection.con_handle = little_endian_read_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 != little_endian_read_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 // check handle 178 if (att_connection.con_handle != hci_event_disconnection_complete_get_connection_handle(packet)) break; 179 att_clear_transaction_queue(&att_connection); 180 att_connection.con_handle = 0; 181 att_handle_value_indication_handle = 0; // reset error state 182 att_server_state = ATT_SERVER_IDLE; 183 break; 184 185 case SM_EVENT_IDENTITY_RESOLVING_STARTED: 186 log_info("SM_EVENT_IDENTITY_RESOLVING_STARTED"); 187 att_ir_lookup_active = 1; 188 break; 189 case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED: 190 att_ir_lookup_active = 0; 191 att_ir_le_device_db_index = little_endian_read_16(packet, 11); 192 log_info("SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED id %u", att_ir_le_device_db_index); 193 att_run(); 194 break; 195 case SM_EVENT_IDENTITY_RESOLVING_FAILED: 196 log_info("SM_EVENT_IDENTITY_RESOLVING_FAILED"); 197 att_ir_lookup_active = 0; 198 att_ir_le_device_db_index = -1; 199 att_run(); 200 break; 201 case SM_EVENT_AUTHORIZATION_RESULT: { 202 if (packet[4] != att_client_addr_type) break; 203 reverse_bd_addr(&packet[5], event_address); 204 if (memcmp(event_address, att_client_address, 6) != 0) break; 205 att_connection.authorized = packet[11]; 206 att_dispatch_server_request_can_send_now_event(att_connection.con_handle); 207 break; 208 } 209 default: 210 break; 211 } 212 break; 213 default: 214 break; 215 } 216 } 217 218 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){ 219 220 if (att_server_state != ATT_SERVER_W4_SIGNED_WRITE_VALIDATION) return; 221 222 uint8_t hash_flipped[8]; 223 reverse_64(hash, hash_flipped); 224 if (memcmp(hash_flipped, &att_request_buffer[att_request_size-8], 8)){ 225 log_info("ATT Signed Write, invalid signature"); 226 att_server_state = ATT_SERVER_IDLE; 227 return; 228 } 229 log_info("ATT Signed Write, valid signature"); 230 231 // update sequence number 232 uint32_t counter_packet = little_endian_read_32(att_request_buffer, att_request_size-12); 233 le_device_db_remote_counter_set(att_ir_le_device_db_index, counter_packet+1); 234 att_server_state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 235 att_dispatch_server_request_can_send_now_event(att_connection.con_handle); 236 } 237 238 #if 0 239 static int att_server_ready_to_send(att_connection_t * connection){ 240 } 241 #endif 242 243 // pre: att_server_state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED 244 // pre: can send now 245 // returns: 1 if packet was sent 246 static int att_server_process_validated_request(hci_con_handle_t con_handle){ 247 248 l2cap_reserve_packet_buffer(); 249 uint8_t * att_response_buffer = l2cap_get_outgoing_buffer(); 250 uint16_t att_response_size = att_handle_request(&att_connection, att_request_buffer, att_request_size, att_response_buffer); 251 252 // intercept "insufficient authorization" for authenticated connections to allow for user authorization 253 if ((att_response_size >= 4) 254 && (att_response_buffer[0] == ATT_ERROR_RESPONSE) 255 && (att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION) 256 && (att_connection.authenticated)){ 257 258 switch (sm_authorization_state(att_connection.con_handle)){ 259 case AUTHORIZATION_UNKNOWN: 260 l2cap_release_packet_buffer(); 261 sm_request_pairing(att_connection.con_handle); 262 return 0; 263 case AUTHORIZATION_PENDING: 264 l2cap_release_packet_buffer(); 265 return 0; 266 default: 267 break; 268 } 269 } 270 271 att_server_state = ATT_SERVER_IDLE; 272 if (att_response_size == 0) { 273 l2cap_release_packet_buffer(); 274 return 0; 275 } 276 277 l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_size); 278 279 // notify client about MTU exchange result 280 if (att_response_buffer[0] == ATT_EXCHANGE_MTU_RESPONSE){ 281 att_emit_mtu_event(att_connection.con_handle, att_connection.mtu); 282 } 283 return 1; 284 } 285 286 static void att_run(void){ 287 switch (att_server_state){ 288 case ATT_SERVER_REQUEST_RECEIVED: 289 if (att_request_buffer[0] == ATT_SIGNED_WRITE_COMMAND){ 290 log_info("ATT Signed Write!"); 291 if (!sm_cmac_ready()) { 292 log_info("ATT Signed Write, sm_cmac engine not ready. Abort"); 293 att_server_state = ATT_SERVER_IDLE; 294 return; 295 } 296 if (att_request_size < (3 + 12)) { 297 log_info("ATT Signed Write, request to short. Abort."); 298 att_server_state = ATT_SERVER_IDLE; 299 return; 300 } 301 if (att_ir_lookup_active){ 302 return; 303 } 304 if (att_ir_le_device_db_index < 0){ 305 log_info("ATT Signed Write, CSRK not available"); 306 att_server_state = ATT_SERVER_IDLE; 307 return; 308 } 309 310 // check counter 311 uint32_t counter_packet = little_endian_read_32(att_request_buffer, att_request_size-12); 312 uint32_t counter_db = le_device_db_remote_counter_get(att_ir_le_device_db_index); 313 log_info("ATT Signed Write, DB counter %"PRIu32", packet counter %"PRIu32, counter_db, counter_packet); 314 if (counter_packet < counter_db){ 315 log_info("ATT Signed Write, db reports higher counter, abort"); 316 att_server_state = ATT_SERVER_IDLE; 317 return; 318 } 319 320 // signature is { sequence counter, secure hash } 321 sm_key_t csrk; 322 le_device_db_remote_csrk_get(att_ir_le_device_db_index, csrk); 323 att_server_state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION; 324 log_info("Orig Signature: "); 325 log_info_hexdump( &att_request_buffer[att_request_size-8], 8); 326 uint16_t attribute_handle = little_endian_read_16(att_request_buffer, 1); 327 sm_cmac_signed_write_start(csrk, att_request_buffer[0], attribute_handle, att_request_size - 15, &att_request_buffer[3], counter_packet, att_signed_write_handle_cmac_result); 328 return; 329 } 330 331 // move on 332 att_server_state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 333 att_dispatch_server_request_can_send_now_event(att_connection.con_handle); 334 break; 335 336 default: 337 break; 338 } 339 } 340 341 static void att_server_handle_can_send_now(void){ 342 343 // NOTE: we get l2cap fixed channel instead of con_handle 344 // TODO: get con_handle 345 346 if (att_server_state == ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED){ 347 int sent = att_server_process_validated_request(att_connection.con_handle); 348 if (sent && att_client_waiting_for_can_send){ 349 att_dispatch_server_request_can_send_now_event(att_connection.con_handle); 350 return; 351 } 352 } 353 354 if (att_client_waiting_for_can_send){ 355 att_client_waiting_for_can_send = 0; 356 att_emit_can_send_now_event(); 357 } 358 } 359 360 static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ 361 switch (packet_type){ 362 363 case HCI_EVENT_PACKET: 364 if (packet[0] != L2CAP_EVENT_CAN_SEND_NOW) break; 365 att_server_handle_can_send_now(); 366 break; 367 368 case ATT_DATA_PACKET: 369 // handle value indication confirms 370 if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_handle_value_indication_handle){ 371 btstack_run_loop_remove_timer(&att_handle_value_indication_timer); 372 uint16_t att_handle = att_handle_value_indication_handle; 373 att_handle_value_indication_handle = 0; 374 att_handle_value_indication_notify_client(0, att_connection.con_handle, att_handle); 375 return; 376 } 377 378 // directly process command 379 // note: signed write cannot be handled directly as authentication needs to be verified 380 if (packet[0] == ATT_WRITE_COMMAND){ 381 att_handle_request(&att_connection, packet, size, 0); 382 return; 383 } 384 385 // check size 386 if (size > sizeof(att_request_buffer)) { 387 log_info("att_packet_handler: dropping att pdu 0x%02x as size %u > att_request_buffer %u", packet[0], size, (int) sizeof(att_request_buffer)); 388 return; 389 } 390 391 // last request still in processing? 392 if (att_server_state != ATT_SERVER_IDLE){ 393 log_info("att_packet_handler: skipping att pdu 0x%02x as server not idle (state %u)", packet[0], att_server_state); 394 return; 395 } 396 397 // store request 398 att_server_state = ATT_SERVER_REQUEST_RECEIVED; 399 att_request_size = size; 400 memcpy(att_request_buffer, packet, size); 401 402 att_run(); 403 break; 404 } 405 } 406 407 void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){ 408 409 // register for HCI Events 410 hci_event_callback_registration.callback = &att_event_packet_handler; 411 hci_add_event_handler(&hci_event_callback_registration); 412 413 // register for SM events 414 sm_event_callback_registration.callback = &att_event_packet_handler; 415 sm_add_event_handler(&sm_event_callback_registration); 416 417 // and L2CAP ATT Server PDUs 418 att_dispatch_register_server(att_packet_handler); 419 420 att_server_state = ATT_SERVER_IDLE; 421 att_set_db(db); 422 att_set_read_callback(read_callback); 423 att_set_write_callback(write_callback); 424 425 } 426 427 void att_server_register_packet_handler(btstack_packet_handler_t handler){ 428 att_client_packet_handler = handler; 429 } 430 431 // NOTE: con_handle is ignored for now as only a single connection is supported 432 // TODO: support multiple connections 433 434 int att_server_can_send_packet_now(hci_con_handle_t con_handle){ 435 if (att_connection.con_handle == 0) return 0; 436 return att_dispatch_server_can_send_now(att_connection.con_handle); 437 } 438 439 void att_server_request_can_send_now_event(hci_con_handle_t con_handle){ 440 att_client_waiting_for_can_send = 1; 441 att_dispatch_server_request_can_send_now_event(att_connection.con_handle); 442 } 443 444 int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 445 if (!att_dispatch_server_can_send_now(att_connection.con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 446 447 l2cap_reserve_packet_buffer(); 448 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 449 uint16_t size = att_prepare_handle_value_notification(&att_connection, attribute_handle, value, value_len, packet_buffer); 450 return l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 451 } 452 453 int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t *value, uint16_t value_len){ 454 if (att_handle_value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PORGRESS; 455 if (!att_dispatch_server_can_send_now(att_connection.con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 456 457 // track indication 458 att_handle_value_indication_handle = attribute_handle; 459 btstack_run_loop_set_timer_handler(&att_handle_value_indication_timer, att_handle_value_indication_timeout); 460 btstack_run_loop_set_timer(&att_handle_value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS); 461 btstack_run_loop_add_timer(&att_handle_value_indication_timer); 462 463 l2cap_reserve_packet_buffer(); 464 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 465 uint16_t size = att_prepare_handle_value_indication(&att_connection, attribute_handle, value, value_len, packet_buffer); 466 l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 467 return 0; 468 } 469