hci/src/hci_layer.c

   1 /******************************************************************************
   2  *
   3  *  Copyright (C) 2014 Google, Inc.
   4  *
   5  *  Licensed under the Apache License, Version 2.0 (the "License");
   6  *  you may not use this file except in compliance with the License.
   7  *  You may obtain a copy of the License at:
   8  *
   9  *  http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  *  Unless required by applicable law or agreed to in writing, software
  12  *  distributed under the License is distributed on an "AS IS" BASIS,
  13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  *  See the License for the specific language governing permissions and
  15  *  limitations under the License.
  16  *
  17  ******************************************************************************/
  18
  19 #define LOG_TAG "bt_hci"
  20
  21 #include "hci_layer.h"
  22
  23 #include <assert.h>
  24 #include <pthread.h>
  25 #include <signal.h>
  26 #include <string.h>
  27 #include <sys/types.h>
  28 #include <unistd.h>
  29
  30 // TODO(armansito): cutils/properties.h is only being used to pull-in runtime
  31 // settings on Android. Remove this conditional include once we have a generic
  32 // way to obtain system properties.
  33 #if !defined(OS_GENERIC)
  34 #include <cutils/properties.h>
  35 #endif  // !defined(OS_GENERIC)
  36
  37 #include "btcore/include/module.h"
  38 #include "btsnoop.h"
  39 #include "buffer_allocator.h"
  40 #include "hci_hal.h"
  41 #include "hci_inject.h"
  42 #include "hci_internals.h"
  43 #include "hcidefs.h"
  44 #include "hcimsgs.h"
  45 #include "low_power_manager.h"
  46 #include "osi/include/list.h"
  47 #include "osi/include/log.h"
  48 #include "osi/include/non_repeating_timer.h"
  49 #include "osi/include/reactor.h"
  50 #include "packet_fragmenter.h"
  51 #include "vendor.h"
  52
  53 // TODO(zachoverflow): remove this hack extern
  54 #include <hardware/bluetooth.h>
  55 bt_bdaddr_t btif_local_bd_addr;
  56
  57 #define INBOUND_PACKET_TYPE_COUNT 3
  58 #define PACKET_TYPE_TO_INBOUND_INDEX(type) ((type) - 2)
  59 #define PACKET_TYPE_TO_INDEX(type) ((type) - 1)
  60
  61 #define PREAMBLE_BUFFER_SIZE 4 // max preamble size, ACL
  62 #define RETRIEVE_ACL_LENGTH(preamble) ((((preamble)[3]) << 8) | (preamble)[2])
  63
  64 static const uint8_t preamble_sizes[] = {
  65   HCI_COMMAND_PREAMBLE_SIZE,
  66   HCI_ACL_PREAMBLE_SIZE,
  67   HCI_SCO_PREAMBLE_SIZE,
  68   HCI_EVENT_PREAMBLE_SIZE
  69 };
  70
  71 static const uint16_t outbound_event_types[] =
  72 {
  73   MSG_HC_TO_STACK_HCI_ERR,
  74   MSG_HC_TO_STACK_HCI_ACL,
  75   MSG_HC_TO_STACK_HCI_SCO,
  76   MSG_HC_TO_STACK_HCI_EVT
  77 };
  78
  79 typedef enum {
  80   BRAND_NEW,
  81   PREAMBLE,
  82   BODY,
  83   IGNORE,
  84   FINISHED
  85 } receive_state_t;
  86
  87 typedef struct {
  88   receive_state_t state;
  89   uint16_t bytes_remaining;
  90   uint8_t preamble[PREAMBLE_BUFFER_SIZE];
  91   uint16_t index;
  92   BT_HDR *buffer;
  93 } packet_receive_data_t;
  94
  95 typedef struct {
  96   uint16_t opcode;
  97   future_t *complete_future;
  98   command_complete_cb complete_callback;
  99   command_status_cb status_callback;
 100   void *context;
 101   BT_HDR *command;
 102 } waiting_command_t;
 103
 104 // Using a define here, because it can be stringified for the property lookup
 105 #define DEFAULT_STARTUP_TIMEOUT_MS 8000
 106 #define STRING_VALUE_OF(x) #x
 107
 108 static const uint32_t EPILOG_TIMEOUT_MS = 3000;
 109 static const uint32_t COMMAND_PENDING_TIMEOUT = 8000;
 110
 111 // Our interface
 112 static bool interface_created;
 113 static hci_t interface;
 114
 115 // Modules we import and callbacks we export
 116 static const allocator_t *buffer_allocator;
 117 static const btsnoop_t *btsnoop;
 118 static const hci_hal_t *hal;
 119 static const hci_hal_callbacks_t hal_callbacks;
 120 static const hci_inject_t *hci_inject;
 121 static const low_power_manager_t *low_power_manager;
 122 static const packet_fragmenter_t *packet_fragmenter;
 123 static const packet_fragmenter_callbacks_t packet_fragmenter_callbacks;
 124 static const vendor_t *vendor;
 125
 126 static future_t *startup_future;
 127 static thread_t *thread; // We own this
 128
 129 static volatile bool firmware_is_configured = false;
 130 static non_repeating_timer_t *epilog_timer;
 131 static non_repeating_timer_t *startup_timer;
 132
 133 // Outbound-related
 134 static int command_credits = 1;
 135 static fixed_queue_t *command_queue;
 136 static fixed_queue_t *packet_queue;
 137
 138 // Inbound-related
 139 static non_repeating_timer_t *command_response_timer;
 140 static list_t *commands_pending_response;
 141 static pthread_mutex_t commands_pending_response_lock;
 142 static packet_receive_data_t incoming_packets[INBOUND_PACKET_TYPE_COUNT];
 143
 144 // The hand-off point for data going to a higher layer, set by the higher layer
 145 static fixed_queue_t *upwards_data_queue;
 146
 147 static future_t *shut_down();
 148
 149 static void event_finish_startup(void *context);
 150 static void firmware_config_callback(bool success);
 151 static void startup_timer_expired(void *context);
 152
 153 static void event_postload(void *context);
 154 static void sco_config_callback(bool success);
 155
 156 static void event_epilog(void *context);
 157 static void epilog_finished_callback(bool success);
 158 static void epilog_timer_expired(void *context);
 159
 160 static void event_command_ready(fixed_queue_t *queue, void *context);
 161 static void event_packet_ready(fixed_queue_t *queue, void *context);
 162 static void command_timed_out(void *context);
 163
 164 static void hal_says_data_ready(serial_data_type_t type);
 165 static bool filter_incoming_event(BT_HDR *packet);
 166
 167 static serial_data_type_t event_to_data_type(uint16_t event);
 168 static waiting_command_t *get_waiting_command(command_opcode_t opcode);
 169
 170 // Module lifecycle functions
 171
 172 static future_t *start_up(void) {
 173   LOG_INFO(LOG_TAG, "%s", __func__);
 174
 175   // The host is only allowed to send at most one command initially,
 176   // as per the Bluetooth spec, Volume 2, Part E, 4.4 (Command Flow Control)
 177   // This value can change when you get a command complete or command status event.
 178   command_credits = 1;
 179   firmware_is_configured = false;
 180
 181   pthread_mutex_init(&commands_pending_response_lock, NULL);
 182
 183   // TODO(armansito): cutils/properties.h is only being used to pull-in runtime
 184   // settings on Android. Remove this conditional include once we have a generic
 185   // way to obtain system properties. For now, always use the default timeout on
 186   // non-Android builds.
 187   period_ms_t startup_timeout_ms = DEFAULT_STARTUP_TIMEOUT_MS;
 188
 189 #if !defined(OS_GENERIC)
 190   // Grab the override startup timeout ms, if present.
 191   char timeout_prop[PROPERTY_VALUE_MAX];
 192   if (!property_get("bluetooth.enable_timeout_ms", timeout_prop, STRING_VALUE_OF(DEFAULT_STARTUP_TIMEOUT_MS))
 193       || (startup_timeout_ms = atoi(timeout_prop)) < 100)
 194     startup_timeout_ms = DEFAULT_STARTUP_TIMEOUT_MS;
 195 #endif  // !defined(OS_GENERIC)
 196
 197   startup_timer = non_repeating_timer_new(startup_timeout_ms, startup_timer_expired, NULL);
 198   if (!startup_timer) {
 199     LOG_ERROR(LOG_TAG, "%s unable to create startup timer.", __func__);
 200     goto error;
 201   }
 202
 203   // Make sure we run in a bounded amount of time
 204   non_repeating_timer_restart(startup_timer);
 205
 206   epilog_timer = non_repeating_timer_new(EPILOG_TIMEOUT_MS, epilog_timer_expired, NULL);
 207   if (!epilog_timer) {
 208     LOG_ERROR(LOG_TAG, "%s unable to create epilog timer.", __func__);
 209     goto error;
 210   }
 211
 212   command_response_timer = non_repeating_timer_new(COMMAND_PENDING_TIMEOUT, command_timed_out, NULL);
 213   if (!command_response_timer) {
 214     LOG_ERROR(LOG_TAG, "%s unable to create command response timer.", __func__);
 215     goto error;
 216   }
 217
 218   command_queue = fixed_queue_new(SIZE_MAX);
 219   if (!command_queue) {
 220     LOG_ERROR(LOG_TAG, "%s unable to create pending command queue.", __func__);
 221     goto error;
 222   }
 223
 224   packet_queue = fixed_queue_new(SIZE_MAX);
 225   if (!packet_queue) {
 226     LOG_ERROR(LOG_TAG, "%s unable to create pending packet queue.", __func__);
 227     goto error;
 228   }
 229
 230   thread = thread_new("hci_thread");
 231   if (!thread) {
 232     LOG_ERROR(LOG_TAG, "%s unable to create thread.", __func__);
 233     goto error;
 234   }
 235
 236   commands_pending_response = list_new(NULL);
 237   if (!commands_pending_response) {
 238     LOG_ERROR(LOG_TAG, "%s unable to create list for commands pending response.", __func__);
 239     goto error;
 240   }
 241
 242   memset(incoming_packets, 0, sizeof(incoming_packets));
 243
 244   packet_fragmenter->init(&packet_fragmenter_callbacks);
 245
 246   fixed_queue_register_dequeue(command_queue, thread_get_reactor(thread), event_command_ready, NULL);
 247   fixed_queue_register_dequeue(packet_queue, thread_get_reactor(thread), event_packet_ready, NULL);
 248
 249   vendor->open(btif_local_bd_addr.address, &interface);
 250   hal->init(&hal_callbacks, thread);
 251   low_power_manager->init(thread);
 252
 253   vendor->set_callback(VENDOR_CONFIGURE_FIRMWARE, firmware_config_callback);
 254   vendor->set_callback(VENDOR_CONFIGURE_SCO, sco_config_callback);
 255   vendor->set_callback(VENDOR_DO_EPILOG, epilog_finished_callback);
 256
 257   if (!hci_inject->open(&interface)) {
 258     // TODO(sharvil): gracefully propagate failures from this layer.
 259   }
 260
 261   int power_state = BT_VND_PWR_OFF;
 262 #if (defined (BT_CLEAN_TURN_ON_DISABLED) && BT_CLEAN_TURN_ON_DISABLED == TRUE)
 263   LOG_WARN(LOG_TAG, "%s not turning off the chip before turning on.", __func__);
 264   // So apparently this hack was needed in the past because a Wingray kernel driver
 265   // didn't handle power off commands in a powered off state correctly.
 266
 267   // The comment in the old code said the workaround should be removed when the
 268   // problem was fixed. Sadly, I have no idea if said bug was fixed or if said
 269   // kernel is still in use, so we must leave this here for posterity. #sadpanda
 270 #else
 271   // cycle power on the chip to ensure it has been reset
 272   vendor->send_command(VENDOR_CHIP_POWER_CONTROL, &power_state);
 273 #endif
 274   power_state = BT_VND_PWR_ON;
 275   vendor->send_command(VENDOR_CHIP_POWER_CONTROL, &power_state);
 276
 277   startup_future = future_new();
 278   LOG_DEBUG(LOG_TAG, "%s starting async portion", __func__);
 279   thread_post(thread, event_finish_startup, NULL);
 280   return startup_future;
 281 error:;
 282   shut_down(); // returns NULL so no need to wait for it
 283   return future_new_immediate(FUTURE_FAIL);
 284 }
 285
 286 static future_t *shut_down() {
 287   LOG_INFO(LOG_TAG, "%s", __func__);
 288
 289   hci_inject->close();
 290
 291   if (thread) {
 292     if (firmware_is_configured) {
 293       non_repeating_timer_restart(epilog_timer);
 294       thread_post(thread, event_epilog, NULL);
 295     } else {
 296       thread_stop(thread);
 297     }
 298
 299     thread_join(thread);
 300   }
 301
 302   fixed_queue_free(command_queue, osi_free);
 303   fixed_queue_free(packet_queue, buffer_allocator->free);
 304   list_free(commands_pending_response);
 305
 306   pthread_mutex_destroy(&commands_pending_response_lock);
 307
 308   packet_fragmenter->cleanup();
 309
 310   non_repeating_timer_free(epilog_timer);
 311   non_repeating_timer_free(command_response_timer);
 312   non_repeating_timer_free(startup_timer);
 313
 314   epilog_timer = NULL;
 315   command_response_timer = NULL;
 316
 317   low_power_manager->cleanup();
 318   hal->close();
 319
 320   // Turn off the chip
 321   int power_state = BT_VND_PWR_OFF;
 322   vendor->send_command(VENDOR_CHIP_POWER_CONTROL, &power_state);
 323   vendor->close();
 324
 325   thread_free(thread);
 326   thread = NULL;
 327   firmware_is_configured = false;
 328
 329   return NULL;
 330 }
 331
 332 EXPORT_SYMBOL const module_t hci_module = {
 333   .name = HCI_MODULE,
 334   .init = NULL,
 335   .start_up = start_up,
 336   .shut_down = shut_down,
 337   .clean_up = NULL,
 338   .dependencies = {
 339     BTSNOOP_MODULE,
 340     NULL
 341   }
 342 };
 343
 344 // Interface functions
 345
 346 static void do_postload() {
 347   LOG_DEBUG(LOG_TAG, "%s posting postload work item", __func__);
 348   thread_post(thread, event_postload, NULL);
 349 }
 350
 351 static void set_data_queue(fixed_queue_t *queue) {
 352   upwards_data_queue = queue;
 353 }
 354
 355 static void transmit_command(
 356     BT_HDR *command,
 357     command_complete_cb complete_callback,
 358     command_status_cb status_callback,
 359     void *context) {
 360   waiting_command_t *wait_entry = osi_calloc(sizeof(waiting_command_t));
 361   if (!wait_entry) {
 362     LOG_ERROR(LOG_TAG, "%s couldn't allocate space for wait entry.", __func__);
 363     return;
 364   }
 365
 366   uint8_t *stream = command->data + command->offset;
 367   STREAM_TO_UINT16(wait_entry->opcode, stream);
 368   wait_entry->complete_callback = complete_callback;
 369   wait_entry->status_callback = status_callback;
 370   wait_entry->command = command;
 371   wait_entry->context = context;
 372
 373   // Store the command message type in the event field
 374   // in case the upper layer didn't already
 375   command->event = MSG_STACK_TO_HC_HCI_CMD;
 376
 377   fixed_queue_enqueue(command_queue, wait_entry);
 378 }
 379
 380 static future_t *transmit_command_futured(BT_HDR *command) {
 381   waiting_command_t *wait_entry = osi_calloc(sizeof(waiting_command_t));
 382   assert(wait_entry != NULL);
 383
 384   future_t *future = future_new();
 385
 386   uint8_t *stream = command->data + command->offset;
 387   STREAM_TO_UINT16(wait_entry->opcode, stream);
 388   wait_entry->complete_future = future;
 389   wait_entry->command = command;
 390
 391   // Store the command message type in the event field
 392   // in case the upper layer didn't already
 393   command->event = MSG_STACK_TO_HC_HCI_CMD;
 394
 395   fixed_queue_enqueue(command_queue, wait_entry);
 396   return future;
 397 }
 398
 399 static void transmit_downward(data_dispatcher_type_t type, void *data) {
 400   if (type == MSG_STACK_TO_HC_HCI_CMD) {
 401     // TODO(zachoverflow): eliminate this call
 402     transmit_command((BT_HDR *)data, NULL, NULL, NULL);
 403     LOG_WARN(LOG_TAG, "%s legacy transmit of command. Use transmit_command instead.", __func__);
 404   } else {
 405     fixed_queue_enqueue(packet_queue, data);
 406   }
 407 }
 408
 409 // Start up functions
 410
 411 static void event_finish_startup(UNUSED_ATTR void *context) {
 412   LOG_INFO(LOG_TAG, "%s", __func__);
 413   hal->open();
 414   vendor->send_async_command(VENDOR_CONFIGURE_FIRMWARE, NULL);
 415 }
 416
 417 static void firmware_config_callback(UNUSED_ATTR bool success) {
 418   LOG_INFO(LOG_TAG, "%s", __func__);
 419   firmware_is_configured = true;
 420   non_repeating_timer_cancel(startup_timer);
 421
 422   future_ready(startup_future, FUTURE_SUCCESS);
 423   startup_future = NULL;
 424 }
 425
 426 static void startup_timer_expired(UNUSED_ATTR void *context) {
 427   LOG_ERROR(LOG_TAG, "%s", __func__);
 428   future_ready(startup_future, FUTURE_FAIL);
 429   startup_future = NULL;
 430 }
 431
 432 // Postload functions
 433
 434 static void event_postload(UNUSED_ATTR void *context) {
 435   LOG_INFO(LOG_TAG, "%s", __func__);
 436   if(vendor->send_async_command(VENDOR_CONFIGURE_SCO, NULL) == -1) {
 437     // If couldn't configure sco, we won't get the sco configuration callback
 438     // so go pretend to do it now
 439     sco_config_callback(false);
 440
 441   }
 442 }
 443
 444 static void sco_config_callback(UNUSED_ATTR bool success) {
 445   LOG_INFO(LOG_TAG, "%s postload finished.", __func__);
 446 }
 447
 448 // Epilog functions
 449
 450 static void event_epilog(UNUSED_ATTR void *context) {
 451   vendor->send_async_command(VENDOR_DO_EPILOG, NULL);
 452 }
 453
 454 static void epilog_finished_callback(UNUSED_ATTR bool success) {
 455   LOG_INFO(LOG_TAG, "%s", __func__);
 456   thread_stop(thread);
 457 }
 458
 459 static void epilog_timer_expired(UNUSED_ATTR void *context) {
 460   LOG_INFO(LOG_TAG, "%s", __func__);
 461   thread_stop(thread);
 462 }
 463
 464 // Command/packet transmitting functions
 465
 466 static void event_command_ready(fixed_queue_t *queue, UNUSED_ATTR void *context) {
 467   if (command_credits > 0) {
 468     waiting_command_t *wait_entry = fixed_queue_dequeue(queue);
 469     command_credits--;
 470
 471     // Move it to the list of commands awaiting response
 472     pthread_mutex_lock(&commands_pending_response_lock);
 473     list_append(commands_pending_response, wait_entry);
 474     pthread_mutex_unlock(&commands_pending_response_lock);
 475
 476     // Send it off
 477     low_power_manager->wake_assert();
 478     packet_fragmenter->fragment_and_dispatch(wait_entry->command);
 479     low_power_manager->transmit_done();
 480
 481     non_repeating_timer_restart_if(command_response_timer, !list_is_empty(commands_pending_response));
 482   }
 483 }
 484
 485 static void event_packet_ready(fixed_queue_t *queue, UNUSED_ATTR void *context) {
 486   // The queue may be the command queue or the packet queue, we don't care
 487   BT_HDR *packet = (BT_HDR *)fixed_queue_dequeue(queue);
 488
 489   low_power_manager->wake_assert();
 490   packet_fragmenter->fragment_and_dispatch(packet);
 491   low_power_manager->transmit_done();
 492 }
 493
 494 // Callback for the fragmenter to send a fragment
 495 static void transmit_fragment(BT_HDR *packet, bool send_transmit_finished) {
 496   uint16_t event = packet->event & MSG_EVT_MASK;
 497   serial_data_type_t type = event_to_data_type(event);
 498
 499   btsnoop->capture(packet, false);
 500   hal->transmit_data(type, packet->data + packet->offset, packet->len);
 501
 502   if (event != MSG_STACK_TO_HC_HCI_CMD && send_transmit_finished)
 503     buffer_allocator->free(packet);
 504 }
 505
 506 static void fragmenter_transmit_finished(BT_HDR *packet, bool all_fragments_sent) {
 507   if (all_fragments_sent) {
 508     buffer_allocator->free(packet);
 509   } else {
 510     // This is kind of a weird case, since we're dispatching a partially sent packet
 511     // up to a higher layer.
 512     // TODO(zachoverflow): rework upper layer so this isn't necessary.
 513     data_dispatcher_dispatch(interface.event_dispatcher, packet->event & MSG_EVT_MASK, packet);
 514   }
 515 }
 516
 517 static void command_timed_out(UNUSED_ATTR void *context) {
 518   pthread_mutex_lock(&commands_pending_response_lock);
 519
 520   if (list_is_empty(commands_pending_response)) {
 521     LOG_ERROR(LOG_TAG, "%s with no commands pending response", __func__);
 522   } else {
 523     waiting_command_t *wait_entry = list_front(commands_pending_response);
 524     pthread_mutex_unlock(&commands_pending_response_lock);
 525
 526     // We shouldn't try to recover the stack from this command timeout.
 527     // If it's caused by a software bug, fix it. If it's a hardware bug, fix it.
 528     LOG_ERROR(LOG_TAG, "%s hci layer timeout waiting for response to a command. opcode: 0x%x", __func__, wait_entry->opcode);
 529   }
 530
 531   LOG_ERROR(LOG_TAG, "%s restarting the bluetooth process.", __func__);
 532   usleep(10000);
 533   kill(getpid(), SIGKILL);
 534 }
 535
 536 // Event/packet receiving functions
 537
 538 // This function is not required to read all of a packet in one go, so
 539 // be wary of reentry. But this function must return after finishing a packet.
 540 static void hal_says_data_ready(serial_data_type_t type) {
 541   packet_receive_data_t *incoming = &incoming_packets[PACKET_TYPE_TO_INBOUND_INDEX(type)];
 542
 543   uint8_t byte;
 544   while (hal->read_data(type, &byte, 1, false) != 0) {
 545     switch (incoming->state) {
 546       case BRAND_NEW:
 547         // Initialize and prepare to jump to the preamble reading state
 548         incoming->bytes_remaining = preamble_sizes[PACKET_TYPE_TO_INDEX(type)];
 549         memset(incoming->preamble, 0, PREAMBLE_BUFFER_SIZE);
 550         incoming->index = 0;
 551         incoming->state = PREAMBLE;
 552         // INTENTIONAL FALLTHROUGH
 553       case PREAMBLE:
 554         incoming->preamble[incoming->index] = byte;
 555         incoming->index++;
 556         incoming->bytes_remaining--;
 557
 558         if (incoming->bytes_remaining == 0) {
 559           // For event and sco preambles, the last byte we read is the length
 560           incoming->bytes_remaining = (type == DATA_TYPE_ACL) ? RETRIEVE_ACL_LENGTH(incoming->preamble) : byte;
 561
 562           size_t buffer_size = BT_HDR_SIZE + incoming->index + incoming->bytes_remaining;
 563           incoming->buffer = (BT_HDR *)buffer_allocator->alloc(buffer_size);
 564
 565           if (!incoming->buffer) {
 566             LOG_ERROR(LOG_TAG, "%s error getting buffer for incoming packet of type %d and size %zd", __func__, type, buffer_size);
 567             // Can't read any more of this current packet, so jump out
 568             incoming->state = incoming->bytes_remaining == 0 ? BRAND_NEW : IGNORE;
 569             break;
 570           }
 571
 572           // Initialize the buffer
 573           incoming->buffer->offset = 0;
 574           incoming->buffer->layer_specific = 0;
 575           incoming->buffer->event = outbound_event_types[PACKET_TYPE_TO_INDEX(type)];
 576           memcpy(incoming->buffer->data, incoming->preamble, incoming->index);
 577
 578           incoming->state = incoming->bytes_remaining > 0 ? BODY : FINISHED;
 579         }
 580
 581         break;
 582       case BODY:
 583         incoming->buffer->data[incoming->index] = byte;
 584         incoming->index++;
 585         incoming->bytes_remaining--;
 586
 587         size_t bytes_read = hal->read_data(type, (incoming->buffer->data + incoming->index), incoming->bytes_remaining, false);
 588         incoming->index += bytes_read;
 589         incoming->bytes_remaining -= bytes_read;
 590
 591         incoming->state = incoming->bytes_remaining == 0 ? FINISHED : incoming->state;
 592         break;
 593       case IGNORE:
 594         incoming->bytes_remaining--;
 595         if (incoming->bytes_remaining == 0) {
 596           incoming->state = BRAND_NEW;
 597           // Don't forget to let the hal know we finished the packet we were ignoring.
 598           // Otherwise we'll get out of sync with hals that embed extra information
 599           // in the uart stream (like H4). #badnewsbears
 600           hal->packet_finished(type);
 601           return;
 602         }
 603
 604         break;
 605       case FINISHED:
 606         LOG_ERROR(LOG_TAG, "%s the state machine should not have been left in the finished state.", __func__);
 607         break;
 608     }
 609
 610     if (incoming->state == FINISHED) {
 611       incoming->buffer->len = incoming->index;
 612       btsnoop->capture(incoming->buffer, true);
 613
 614       if (type != DATA_TYPE_EVENT) {
 615         packet_fragmenter->reassemble_and_dispatch(incoming->buffer);
 616       } else if (!filter_incoming_event(incoming->buffer)) {
 617         // Dispatch the event by event code
 618         uint8_t *stream = incoming->buffer->data;
 619         uint8_t event_code;
 620         STREAM_TO_UINT8(event_code, stream);
 621
 622         data_dispatcher_dispatch(
 623           interface.event_dispatcher,
 624           event_code,
 625           incoming->buffer
 626         );
 627       }
 628
 629       // We don't control the buffer anymore
 630       incoming->buffer = NULL;
 631       incoming->state = BRAND_NEW;
 632       hal->packet_finished(type);
 633
 634       // We return after a packet is finished for two reasons:
 635       // 1. The type of the next packet could be different.
 636       // 2. We don't want to hog cpu time.
 637       return;
 638     }
 639   }
 640 }
 641
 642 // Returns true if the event was intercepted and should not proceed to
 643 // higher layers. Also inspects an incoming event for interesting
 644 // information, like how many commands are now able to be sent.
 645 static bool filter_incoming_event(BT_HDR *packet) {
 646   waiting_command_t *wait_entry = NULL;
 647   uint8_t *stream = packet->data;
 648   uint8_t event_code;
 649   command_opcode_t opcode;
 650
 651   STREAM_TO_UINT8(event_code, stream);
 652   STREAM_SKIP_UINT8(stream); // Skip the parameter total length field
 653
 654   if (event_code == HCI_COMMAND_COMPLETE_EVT) {
 655     STREAM_TO_UINT8(command_credits, stream);
 656     STREAM_TO_UINT16(opcode, stream);
 657
 658     wait_entry = get_waiting_command(opcode);
 659     if (!wait_entry)
 660       LOG_WARN(LOG_TAG, "%s command complete event with no matching command. opcode: 0x%x.", __func__, opcode);
 661     else if (wait_entry->complete_callback)
 662       wait_entry->complete_callback(packet, wait_entry->context);
 663     else if (wait_entry->complete_future)
 664       future_ready(wait_entry->complete_future, packet);
 665
 666     goto intercepted;
 667   } else if (event_code == HCI_COMMAND_STATUS_EVT) {
 668     uint8_t status;
 669     STREAM_TO_UINT8(status, stream);
 670     STREAM_TO_UINT8(command_credits, stream);
 671     STREAM_TO_UINT16(opcode, stream);
 672
 673     // If a command generates a command status event, it won't be getting a command complete event
 674
 675     wait_entry = get_waiting_command(opcode);
 676     if (!wait_entry)
 677       LOG_WARN(LOG_TAG, "%s command status event with no matching command. opcode: 0x%x", __func__, opcode);
 678     else if (wait_entry->status_callback)
 679       wait_entry->status_callback(status, wait_entry->command, wait_entry->context);
 680
 681     goto intercepted;
 682   }
 683
 684   return false;
 685 intercepted:;
 686   non_repeating_timer_restart_if(command_response_timer, !list_is_empty(commands_pending_response));
 687
 688   if (wait_entry) {
 689     // If it has a callback, it's responsible for freeing the packet
 690     if (event_code == HCI_COMMAND_STATUS_EVT || (!wait_entry->complete_callback && !wait_entry->complete_future))
 691       buffer_allocator->free(packet);
 692
 693     // If it has a callback, it's responsible for freeing the command
 694     if (event_code == HCI_COMMAND_COMPLETE_EVT || !wait_entry->status_callback)
 695       buffer_allocator->free(wait_entry->command);
 696
 697     osi_free(wait_entry);
 698   } else {
 699     buffer_allocator->free(packet);
 700   }
 701
 702   return true;
 703 }
 704
 705 // Callback for the fragmenter to dispatch up a completely reassembled packet
 706 static void dispatch_reassembled(BT_HDR *packet) {
 707   // Events should already have been dispatched before this point
 708   assert((packet->event & MSG_EVT_MASK) != MSG_HC_TO_STACK_HCI_EVT);
 709   assert(upwards_data_queue != NULL);
 710
 711   if (upwards_data_queue) {
 712     fixed_queue_enqueue(upwards_data_queue, packet);
 713   } else {
 714     LOG_ERROR(LOG_TAG, "%s had no queue to place upwards data packet in. Dropping it on the floor.", __func__);
 715     buffer_allocator->free(packet);
 716   }
 717 }
 718
 719 // Misc internal functions
 720
 721 // TODO(zachoverflow): we seem to do this a couple places, like the HCI inject module. #centralize
 722 static serial_data_type_t event_to_data_type(uint16_t event) {
 723   if (event == MSG_STACK_TO_HC_HCI_ACL)
 724     return DATA_TYPE_ACL;
 725   else if (event == MSG_STACK_TO_HC_HCI_SCO)
 726     return DATA_TYPE_SCO;
 727   else if (event == MSG_STACK_TO_HC_HCI_CMD)
 728     return DATA_TYPE_COMMAND;
 729   else
 730     LOG_ERROR(LOG_TAG, "%s invalid event type, could not translate 0x%x", __func__, event);
 731
 732   return 0;
 733 }
 734
 735 static waiting_command_t *get_waiting_command(command_opcode_t opcode) {
 736   pthread_mutex_lock(&commands_pending_response_lock);
 737
 738   for (const list_node_t *node = list_begin(commands_pending_response);
 739       node != list_end(commands_pending_response);
 740       node = list_next(node)) {
 741     waiting_command_t *wait_entry = list_node(node);
 742
 743     if (!wait_entry || wait_entry->opcode != opcode)
 744       continue;
 745
 746     list_remove(commands_pending_response, wait_entry);
 747
 748     pthread_mutex_unlock(&commands_pending_response_lock);
 749     return wait_entry;
 750   }
 751
 752   pthread_mutex_unlock(&commands_pending_response_lock);
 753   return NULL;
 754 }
 755
 756 static void init_layer_interface() {
 757   if (!interface_created) {
 758     interface.send_low_power_command = low_power_manager->post_command;
 759     interface.do_postload = do_postload;
 760
 761     // It's probably ok for this to live forever. It's small and
 762     // there's only one instance of the hci interface.
 763     interface.event_dispatcher = data_dispatcher_new("hci_layer");
 764     if (!interface.event_dispatcher) {
 765       LOG_ERROR(LOG_TAG, "%s could not create upward dispatcher.", __func__);
 766       return;
 767     }
 768
 769     interface.set_data_queue = set_data_queue;
 770     interface.transmit_command = transmit_command;
 771     interface.transmit_command_futured = transmit_command_futured;
 772     interface.transmit_downward = transmit_downward;
 773     interface_created = true;
 774   }
 775 }
 776
 777 static const hci_hal_callbacks_t hal_callbacks = {
 778   hal_says_data_ready
 779 };
 780
 781 static const packet_fragmenter_callbacks_t packet_fragmenter_callbacks = {
 782   transmit_fragment,
 783   dispatch_reassembled,
 784   fragmenter_transmit_finished
 785 };
 786
 787 const hci_t *hci_layer_get_interface() {
 788   buffer_allocator = buffer_allocator_get_interface();
 789   hal = hci_hal_get_interface();
 790   btsnoop = btsnoop_get_interface();
 791   hci_inject = hci_inject_get_interface();
 792   packet_fragmenter = packet_fragmenter_get_interface();
 793   vendor = vendor_get_interface();
 794   low_power_manager = low_power_manager_get_interface();
 795
 796   init_layer_interface();
 797   return &interface;
 798 }
 799
 800 const hci_t *hci_layer_get_test_interface(
 801     const allocator_t *buffer_allocator_interface,
 802     const hci_hal_t *hal_interface,
 803     const btsnoop_t *btsnoop_interface,
 804     const hci_inject_t *hci_inject_interface,
 805     const packet_fragmenter_t *packet_fragmenter_interface,
 806     const vendor_t *vendor_interface,
 807     const low_power_manager_t *low_power_manager_interface) {
 808
 809   buffer_allocator = buffer_allocator_interface;
 810   hal = hal_interface;
 811   btsnoop = btsnoop_interface;
 812   hci_inject = hci_inject_interface;
 813   packet_fragmenter = packet_fragmenter_interface;
 814   vendor = vendor_interface;
 815   low_power_manager = low_power_manager_interface;
 816
 817   init_layer_interface();
 818   return &interface;
 819 }