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 "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 "ble/gap_le.h" 63 #include "ble/le_device_db.h" 64 65 #include "ble/att_server.h" 66 67 static void att_run(void); 68 69 typedef enum { 70 ATT_SERVER_IDLE, 71 ATT_SERVER_REQUEST_RECEIVED, 72 ATT_SERVER_W4_SIGNED_WRITE_VALIDATION, 73 ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED, 74 } att_server_state_t; 75 76 static att_connection_t att_connection; 77 static att_server_state_t att_server_state; 78 79 static uint8_t att_client_addr_type; 80 static bd_addr_t att_client_address; 81 static uint16_t att_request_size = 0; 82 static uint8_t att_request_buffer[HCI_ACL_PAYLOAD_SIZE]; 83 84 static int att_ir_le_device_db_index = -1; 85 static int att_ir_lookup_active = 0; 86 87 static int att_handle_value_indication_handle = 0; 88 static timer_source_t att_handle_value_indication_timer; 89 90 static btstack_packet_handler_t att_client_packet_handler = NULL; 91 92 static void att_handle_value_indication_notify_client(uint8_t status, uint16_t client_handle, uint16_t attribute_handle){ 93 94 if (!att_client_packet_handler) return; 95 96 uint8_t event[7]; 97 int pos = 0; 98 event[pos++] = ATT_HANDLE_VALUE_INDICATION_COMPLETE; 99 event[pos++] = sizeof(event) - 2; 100 event[pos++] = status; 101 bt_store_16(event, pos, client_handle); 102 pos += 2; 103 bt_store_16(event, pos, attribute_handle); 104 pos += 2; 105 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 106 } 107 108 static void att_emit_mtu_event(uint16_t handle, uint16_t mtu){ 109 110 if (!att_client_packet_handler) return; 111 112 uint8_t event[6]; 113 int pos = 0; 114 event[pos++] = ATT_MTU_EXCHANGE_COMPLETE; 115 event[pos++] = sizeof(event) - 2; 116 bt_store_16(event, pos, handle); 117 pos += 2; 118 bt_store_16(event, pos, mtu); 119 pos += 2; 120 (*att_client_packet_handler)(HCI_EVENT_PACKET, 0, &event[0], sizeof(event)); 121 } 122 123 static void att_handle_value_indication_timeout(timer_source_t *ts){ 124 uint16_t att_handle = att_handle_value_indication_handle; 125 att_handle_value_indication_notify_client(ATT_HANDLE_VALUE_INDICATION_TIMEOUT, att_connection.con_handle, att_handle); 126 } 127 128 static void att_event_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){ 129 130 bd_addr_t event_address; 131 switch (packet_type) { 132 133 case HCI_EVENT_PACKET: 134 switch (packet[0]) { 135 136 case DAEMON_EVENT_HCI_PACKET_SENT: 137 att_run(); 138 break; 139 140 case HCI_EVENT_LE_META: 141 switch (packet[2]) { 142 case HCI_SUBEVENT_LE_CONNECTION_COMPLETE: 143 // store connection info 144 att_client_addr_type = packet[7]; 145 bt_flip_addr(att_client_address, &packet[8]); 146 // reset connection properties 147 att_connection.con_handle = READ_BT_16(packet, 4); 148 att_connection.mtu = ATT_DEFAULT_MTU; 149 att_connection.max_mtu = l2cap_max_le_mtu(); 150 att_connection.encryption_key_size = 0; 151 att_connection.authenticated = 0; 152 att_connection.authorized = 0; 153 break; 154 155 default: 156 break; 157 } 158 break; 159 160 case HCI_EVENT_ENCRYPTION_CHANGE: 161 case HCI_EVENT_ENCRYPTION_KEY_REFRESH_COMPLETE: 162 // check handle 163 if (att_connection.con_handle != READ_BT_16(packet, 3)) break; 164 att_connection.encryption_key_size = sm_encryption_key_size(att_connection.con_handle); 165 att_connection.authenticated = sm_authenticated(att_connection.con_handle); 166 break; 167 168 case HCI_EVENT_DISCONNECTION_COMPLETE: 169 att_clear_transaction_queue(&att_connection); 170 att_connection.con_handle = 0; 171 att_handle_value_indication_handle = 0; // reset error state 172 // restart advertising if we have been connected before 173 // -> avoid sending advertise enable a second time before command complete was received 174 att_server_state = ATT_SERVER_IDLE; 175 break; 176 177 case SM_IDENTITY_RESOLVING_STARTED: 178 log_info("SM_IDENTITY_RESOLVING_STARTED"); 179 att_ir_lookup_active = 1; 180 break; 181 case SM_IDENTITY_RESOLVING_SUCCEEDED: 182 att_ir_lookup_active = 0; 183 att_ir_le_device_db_index = READ_BT_16(packet, 11); 184 log_info("SM_IDENTITY_RESOLVING_SUCCEEDED id %u", att_ir_le_device_db_index); 185 att_run(); 186 break; 187 case SM_IDENTITY_RESOLVING_FAILED: 188 log_info("SM_IDENTITY_RESOLVING_FAILED"); 189 att_ir_lookup_active = 0; 190 att_ir_le_device_db_index = -1; 191 att_run(); 192 break; 193 194 case SM_AUTHORIZATION_RESULT: { 195 if (packet[4] != att_client_addr_type) break; 196 bt_flip_addr(event_address, &packet[5]); 197 if (memcmp(event_address, att_client_address, 6) != 0) break; 198 att_connection.authorized = packet[11]; 199 att_run(); 200 break; 201 } 202 203 default: 204 break; 205 } 206 } 207 if (att_client_packet_handler){ 208 att_client_packet_handler(packet_type, channel, packet, size); 209 } 210 } 211 212 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){ 213 214 if (att_server_state != ATT_SERVER_W4_SIGNED_WRITE_VALIDATION) return; 215 216 uint8_t hash_flipped[8]; 217 swap64(hash, hash_flipped); 218 if (memcmp(hash_flipped, &att_request_buffer[att_request_size-8], 8)){ 219 log_info("ATT Signed Write, invalid signature"); 220 att_server_state = ATT_SERVER_IDLE; 221 return; 222 } 223 log_info("ATT Signed Write, valid signature"); 224 225 // update sequence number 226 uint32_t counter_packet = READ_BT_32(att_request_buffer, att_request_size-12); 227 le_device_db_remote_counter_set(att_ir_le_device_db_index, counter_packet+1); 228 att_server_state = ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED; 229 att_run(); 230 } 231 232 static void att_run(void){ 233 switch (att_server_state){ 234 case ATT_SERVER_IDLE: 235 case ATT_SERVER_W4_SIGNED_WRITE_VALIDATION: 236 return; 237 case ATT_SERVER_REQUEST_RECEIVED: 238 if (att_request_buffer[0] == ATT_SIGNED_WRITE_COMMAND){ 239 log_info("ATT Signed Write!"); 240 if (!sm_cmac_ready()) { 241 log_info("ATT Signed Write, sm_cmac engine not ready. Abort"); 242 att_server_state = ATT_SERVER_IDLE; 243 return; 244 } 245 if (att_request_size < (3 + 12)) { 246 log_info("ATT Signed Write, request to short. Abort."); 247 att_server_state = ATT_SERVER_IDLE; 248 return; 249 } 250 if (att_ir_lookup_active){ 251 return; 252 } 253 if (att_ir_le_device_db_index < 0){ 254 log_info("ATT Signed Write, CSRK not available"); 255 att_server_state = ATT_SERVER_IDLE; 256 return; 257 } 258 259 // check counter 260 uint32_t counter_packet = READ_BT_32(att_request_buffer, att_request_size-12); 261 uint32_t counter_db = le_device_db_remote_counter_get(att_ir_le_device_db_index); 262 log_info("ATT Signed Write, DB counter %"PRIu32", packet counter %"PRIu32, counter_db, counter_packet); 263 if (counter_packet < counter_db){ 264 log_info("ATT Signed Write, db reports higher counter, abort"); 265 att_server_state = ATT_SERVER_IDLE; 266 return; 267 } 268 269 // signature is { sequence counter, secure hash } 270 sm_key_t csrk; 271 le_device_db_remote_csrk_get(att_ir_le_device_db_index, csrk); 272 att_server_state = ATT_SERVER_W4_SIGNED_WRITE_VALIDATION; 273 log_info("Orig Signature: "); 274 hexdump( &att_request_buffer[att_request_size-8], 8); 275 uint16_t attribute_handle = READ_BT_16(att_request_buffer, 1); 276 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); 277 return; 278 } 279 // NOTE: fall through for regular commands 280 281 case ATT_SERVER_REQUEST_RECEIVED_AND_VALIDATED: 282 if (!l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle)) return; 283 284 l2cap_reserve_packet_buffer(); 285 uint8_t * att_response_buffer = l2cap_get_outgoing_buffer(); 286 uint16_t att_response_size = att_handle_request(&att_connection, att_request_buffer, att_request_size, att_response_buffer); 287 288 // intercept "insufficient authorization" for authenticated connections to allow for user authorization 289 if ((att_response_size >= 4) 290 && (att_response_buffer[0] == ATT_ERROR_RESPONSE) 291 && (att_response_buffer[4] == ATT_ERROR_INSUFFICIENT_AUTHORIZATION) 292 && (att_connection.authenticated)){ 293 294 switch (sm_authorization_state(att_connection.con_handle)){ 295 case AUTHORIZATION_UNKNOWN: 296 l2cap_release_packet_buffer(); 297 sm_request_pairing(att_connection.con_handle); 298 return; 299 case AUTHORIZATION_PENDING: 300 l2cap_release_packet_buffer(); 301 return; 302 default: 303 break; 304 } 305 } 306 307 att_server_state = ATT_SERVER_IDLE; 308 if (att_response_size == 0) { 309 l2cap_release_packet_buffer(); 310 return; 311 } 312 313 l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, att_response_size); 314 315 // notify client about MTU exchange result 316 if (att_response_buffer[0] == ATT_EXCHANGE_MTU_RESPONSE){ 317 att_emit_mtu_event(att_connection.con_handle, att_connection.mtu); 318 } 319 320 break; 321 } 322 } 323 324 static void att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){ 325 if (packet_type != ATT_DATA_PACKET) return; 326 327 // handle value indication confirms 328 if (packet[0] == ATT_HANDLE_VALUE_CONFIRMATION && att_handle_value_indication_handle){ 329 run_loop_remove_timer(&att_handle_value_indication_timer); 330 uint16_t att_handle = att_handle_value_indication_handle; 331 att_handle_value_indication_handle = 0; 332 att_handle_value_indication_notify_client(0, att_connection.con_handle, att_handle); 333 return; 334 } 335 336 // check size 337 if (size > sizeof(att_request_buffer)) return; 338 339 // last request still in processing? 340 if (att_server_state != ATT_SERVER_IDLE) return; 341 342 // store request 343 att_server_state = ATT_SERVER_REQUEST_RECEIVED; 344 att_request_size = size; 345 memcpy(att_request_buffer, packet, size); 346 347 att_run(); 348 } 349 350 void att_server_init(uint8_t const * db, att_read_callback_t read_callback, att_write_callback_t write_callback){ 351 352 sm_register_packet_handler(att_event_packet_handler); 353 354 att_dispatch_register_server(att_packet_handler); 355 356 att_server_state = ATT_SERVER_IDLE; 357 att_set_db(db); 358 att_set_read_callback(read_callback); 359 att_set_write_callback(write_callback); 360 361 } 362 363 void att_server_register_packet_handler(btstack_packet_handler_t handler){ 364 att_client_packet_handler = handler; 365 } 366 367 int att_server_can_send(void){ 368 if (att_connection.con_handle == 0) return 0; 369 return l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle); 370 } 371 372 int att_server_notify(uint16_t handle, uint8_t *value, uint16_t value_len){ 373 if (!l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 374 375 l2cap_reserve_packet_buffer(); 376 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 377 uint16_t size = att_prepare_handle_value_notification(&att_connection, handle, value, value_len, packet_buffer); 378 return l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 379 } 380 381 int att_server_indicate(uint16_t handle, uint8_t *value, uint16_t value_len){ 382 if (att_handle_value_indication_handle) return ATT_HANDLE_VALUE_INDICATION_IN_PORGRESS; 383 if (!l2cap_can_send_fixed_channel_packet_now(att_connection.con_handle)) return BTSTACK_ACL_BUFFERS_FULL; 384 385 // track indication 386 att_handle_value_indication_handle = handle; 387 run_loop_set_timer_handler(&att_handle_value_indication_timer, att_handle_value_indication_timeout); 388 run_loop_set_timer(&att_handle_value_indication_timer, ATT_TRANSACTION_TIMEOUT_MS); 389 run_loop_add_timer(&att_handle_value_indication_timer); 390 391 l2cap_reserve_packet_buffer(); 392 uint8_t * packet_buffer = l2cap_get_outgoing_buffer(); 393 uint16_t size = att_prepare_handle_value_indication(&att_connection, handle, value, value_len, packet_buffer); 394 l2cap_send_prepared_connectionless(att_connection.con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size); 395 return 0; 396 } 397