bluetooth: add aidl hal

* Copy from hardware/interfaces/bluetooth/aidl/default
  at 488942f82bd1bc9ad1cb65a02c71421dc3a6a3d6.

bluetooth/Android.bp

@@ -0,0 +1,85 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_defaults {
+    name: "android.hardware.bluetooth-service-build-defaults",
+    cflags: [
+        "-Wall",
+        "-Wextra",
+    ],
+    shared_libs: [
+        "android.hardware.bluetooth-V1-ndk",
+        "libbase",
+        "libbinder_ndk",
+        "libcutils",
+        "libhidlbase",
+        "liblog",
+        "libutils",
+    ],
+    static_libs: [
+        "android.hardware.bluetooth.async",
+        "android.hardware.bluetooth.hci",
+    ],
+}
+
+cc_library_static {
+    name: "libbluetoothhcihalimpl",
+    vendor_available: true,
+    host_supported: true,
+    defaults: ["android.hardware.bluetooth-service-build-defaults"],
+    srcs: [
+        "BluetoothHci.cpp",
+        "net_bluetooth_mgmt.cpp",
+    ],
+}
+
+cc_binary {
+    name: "android.hardware.bluetooth-service.default",
+    relative_install_path: "hw",
+    init_rc: ["bluetooth-service-default.rc"],
+    vintf_fragments: [":manifest_android.hardware.bluetooth-service.default.xml"],
+    vendor: true,
+    defaults: ["android.hardware.bluetooth-service-build-defaults"],
+    srcs: [
+        "service.cpp",
+    ],
+    shared_libs: [
+        "android.hardware.bluetooth-V1-ndk",
+        "libbase",
+        "libbinder_ndk",
+        "libhidlbase",
+        "libutils",
+        "liblog",
+    ],
+    static_libs: [
+        "libbluetoothhcihalimpl",
+    ],
+}
+
+cc_fuzz {
+    name: "android.hardware.bluetooth-service.default_fuzzer",
+    host_supported: true,
+    defaults: ["service_fuzzer_defaults"],
+    srcs: [
+        "test/fuzzer.cpp",
+    ],
+    static_libs: [
+        "android.hardware.bluetooth.async",
+        "android.hardware.bluetooth.hci",
+        "android.hardware.bluetooth-V1-ndk",
+        "libbluetoothhcihalimpl",
+        "liblog",
+    ],
+    fuzz_config: {
+        componentid: 27441,
+        cc: [
+            "mylesgw@google.com",
+        ],
+    },
+}
+
+filegroup {
+    name: "manifest_android.hardware.bluetooth-service.default.xml",
+    srcs: ["bluetooth-service-default.xml"],
+}

bluetooth/BluetoothHci.cpp

@@ -0,0 +1,364 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "android.hardware.bluetooth.service.default"
+
+#include "BluetoothHci.h"
+
+#include <cutils/properties.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <poll.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <termios.h>
+
+#include "log/log.h"
+
+namespace {
+int SetTerminalRaw(int fd) {
+  termios terminal_settings;
+  int rval = tcgetattr(fd, &terminal_settings);
+  if (rval < 0) {
+    return rval;
+  }
+  cfmakeraw(&terminal_settings);
+  rval = tcsetattr(fd, TCSANOW, &terminal_settings);
+  return rval;
+}
+}  // namespace
+
+using namespace ::android::hardware::bluetooth::hci;
+using namespace ::android::hardware::bluetooth::async;
+using aidl::android::hardware::bluetooth::Status;
+
+namespace aidl::android::hardware::bluetooth::impl {
+
+void OnDeath(void* cookie);
+
+std::optional<std::string> GetSystemProperty(const std::string& property) {
+  std::array<char, PROPERTY_VALUE_MAX> value_array{0};
+  auto value_len = property_get(property.c_str(), value_array.data(), nullptr);
+  if (value_len <= 0) {
+    return std::nullopt;
+  }
+  return std::string(value_array.data(), value_len);
+}
+
+bool starts_with(const std::string& str, const std::string& prefix) {
+  return str.compare(0, prefix.length(), prefix) == 0;
+}
+
+class BluetoothDeathRecipient {
+ public:
+  BluetoothDeathRecipient(BluetoothHci* hci) : mHci(hci) {}
+
+  void LinkToDeath(const std::shared_ptr<IBluetoothHciCallbacks>& cb) {
+    mCb = cb;
+    clientDeathRecipient_ = AIBinder_DeathRecipient_new(OnDeath);
+    auto linkToDeathReturnStatus = AIBinder_linkToDeath(
+        mCb->asBinder().get(), clientDeathRecipient_, this /* cookie */);
+    LOG_ALWAYS_FATAL_IF(linkToDeathReturnStatus != STATUS_OK,
+                        "Unable to link to death recipient");
+  }
+
+  void UnlinkToDeath(const std::shared_ptr<IBluetoothHciCallbacks>& cb) {
+    LOG_ALWAYS_FATAL_IF(cb != mCb, "Unable to unlink mismatched pointers");
+  }
+
+  void serviceDied() {
+    if (mCb != nullptr && !AIBinder_isAlive(mCb->asBinder().get())) {
+      ALOGE("Bluetooth remote service has died");
+    } else {
+      ALOGE("BluetoothDeathRecipient::serviceDied called but service not dead");
+      return;
+    }
+    {
+      std::lock_guard<std::mutex> guard(mHasDiedMutex);
+      has_died_ = true;
+    }
+    mHci->close();
+  }
+  BluetoothHci* mHci;
+  std::shared_ptr<IBluetoothHciCallbacks> mCb;
+  AIBinder_DeathRecipient* clientDeathRecipient_;
+  bool getHasDied() {
+    std::lock_guard<std::mutex> guard(mHasDiedMutex);
+    return has_died_;
+  }
+
+ private:
+  std::mutex mHasDiedMutex;
+  bool has_died_{false};
+};
+
+void OnDeath(void* cookie) {
+  auto* death_recipient = static_cast<BluetoothDeathRecipient*>(cookie);
+  death_recipient->serviceDied();
+}
+
+BluetoothHci::BluetoothHci(const std::string& dev_path) {
+  char property_bytes[PROPERTY_VALUE_MAX];
+  property_get("vendor.ser.bt-uart", property_bytes, dev_path.c_str());
+  mDevPath = std::string(property_bytes);
+  mDeathRecipient = std::make_shared<BluetoothDeathRecipient>(this);
+}
+
+int BluetoothHci::getFdFromDevPath() {
+  int fd = open(mDevPath.c_str(), O_RDWR);
+  if (fd < 0) {
+    ALOGE("Could not connect to bt: %s (%s)", mDevPath.c_str(),
+          strerror(errno));
+    return fd;
+  }
+  if (int ret = SetTerminalRaw(fd) < 0) {
+    ALOGI("Could not make %s a raw terminal %d(%s)", mDevPath.c_str(), ret,
+          strerror(errno));
+  }
+  return fd;
+}
+
+void BluetoothHci::reset() {
+  // Send a reset command and wait until the command complete comes back.
+
+  std::vector<uint8_t> reset = {0x03, 0x0c, 0x00};
+
+  auto resetPromise = std::make_shared<std::promise<void>>();
+  auto resetFuture = resetPromise->get_future();
+
+  mH4 = std::make_shared<H4Protocol>(
+      mFd,
+      [](const std::vector<uint8_t>& raw_command) {
+        ALOGI("Discarding %d bytes with command type",
+              static_cast<int>(raw_command.size()));
+      },
+      [](const std::vector<uint8_t>& raw_acl) {
+        ALOGI("Discarding %d bytes with acl type",
+              static_cast<int>(raw_acl.size()));
+      },
+      [](const std::vector<uint8_t>& raw_sco) {
+        ALOGI("Discarding %d bytes with sco type",
+              static_cast<int>(raw_sco.size()));
+      },
+      [resetPromise](const std::vector<uint8_t>& raw_event) {
+        std::vector<uint8_t> reset_complete = {0x0e, 0x04, 0x01,
+                                               0x03, 0x0c, 0x00};
+        bool valid = raw_event.size() == 6 &&
+                     raw_event[0] == reset_complete[0] &&
+                     raw_event[1] == reset_complete[1] &&
+                     // Don't compare the number of packets field.
+                     raw_event[3] == reset_complete[3] &&
+                     raw_event[4] == reset_complete[4] &&
+                     raw_event[5] == reset_complete[5];
+        if (valid) {
+          resetPromise->set_value();
+        } else {
+          ALOGI("Discarding %d bytes with event type",
+                static_cast<int>(raw_event.size()));
+        }
+      },
+      [](const std::vector<uint8_t>& raw_iso) {
+        ALOGI("Discarding %d bytes with iso type",
+              static_cast<int>(raw_iso.size()));
+      },
+      [this]() {
+        ALOGI("HCI socket device disconnected while waiting for reset");
+        mFdWatcher.StopWatchingFileDescriptors();
+      });
+  mFdWatcher.WatchFdForNonBlockingReads(mFd,
+                                        [this](int) { mH4->OnDataReady(); });
+
+  ndk::ScopedAStatus result = send(PacketType::COMMAND, reset);
+  if (!result.isOk()) {
+    ALOGE("Error sending reset command");
+  }
+  auto status = resetFuture.wait_for(std::chrono::seconds(1));
+  mFdWatcher.StopWatchingFileDescriptors();
+  if (status == std::future_status::ready) {
+    ALOGI("HCI Reset successful");
+  } else {
+    ALOGE("HCI Reset Response not received in one second");
+  }
+
+  resetPromise.reset();
+}
+
+ndk::ScopedAStatus BluetoothHci::initialize(
+    const std::shared_ptr<IBluetoothHciCallbacks>& cb) {
+  ALOGI(__func__);
+
+  if (cb == nullptr) {
+    ALOGE("cb == nullptr! -> Unable to call initializationComplete(ERR)");
+    return ndk::ScopedAStatus::fromServiceSpecificError(STATUS_BAD_VALUE);
+  }
+
+  HalState old_state = HalState::READY;
+  {
+    std::lock_guard<std::mutex> guard(mStateMutex);
+    if (mState != HalState::READY) {
+      old_state = mState;
+    } else {
+      mState = HalState::INITIALIZING;
+    }
+  }
+
+  if (old_state != HalState::READY) {
+    ALOGE("initialize: Unexpected State %d", static_cast<int>(old_state));
+    close();
+    cb->initializationComplete(Status::ALREADY_INITIALIZED);
+    return ndk::ScopedAStatus::ok();
+  }
+
+  mCb = cb;
+  management_.reset(new NetBluetoothMgmt);
+  mFd = management_->openHci();
+  if (mFd < 0) {
+    management_.reset();
+
+    ALOGI("Unable to open Linux interface, trying default path.");
+    mFd = getFdFromDevPath();
+    if (mFd < 0) {
+      mState = HalState::READY;
+      cb->initializationComplete(Status::UNABLE_TO_OPEN_INTERFACE);
+      return ndk::ScopedAStatus::ok();
+    }
+  }
+
+  mDeathRecipient->LinkToDeath(mCb);
+
+  // TODO: HCI Reset on emulators since the bluetooth controller
+  // cannot be powered on/off during the HAL setup; and the stack
+  // might received spurious packets/events during boottime.
+  // Proper solution would be to use bt-virtio or vsock to better
+  // control the link to rootcanal and the controller lifetime.
+  const std::string kBoardProperty = "ro.product.board";
+  const std::string kCuttlefishBoard = "cutf";
+  auto board_name = GetSystemProperty(kBoardProperty);
+  if (board_name.has_value() && (
+        starts_with(board_name.value(), "cutf") ||
+        starts_with(board_name.value(), "goldfish"))) {
+    reset();
+  }
+
+  mH4 = std::make_shared<H4Protocol>(
+      mFd,
+      [](const std::vector<uint8_t>& /* raw_command */) {
+        LOG_ALWAYS_FATAL("Unexpected command!");
+      },
+      [this](const std::vector<uint8_t>& raw_acl) {
+        mCb->aclDataReceived(raw_acl);
+      },
+      [this](const std::vector<uint8_t>& raw_sco) {
+        mCb->scoDataReceived(raw_sco);
+      },
+      [this](const std::vector<uint8_t>& raw_event) {
+        mCb->hciEventReceived(raw_event);
+      },
+      [this](const std::vector<uint8_t>& raw_iso) {
+        mCb->isoDataReceived(raw_iso);
+      },
+      [this]() {
+        ALOGI("HCI socket device disconnected");
+        mFdWatcher.StopWatchingFileDescriptors();
+      });
+  mFdWatcher.WatchFdForNonBlockingReads(mFd,
+                                        [this](int) { mH4->OnDataReady(); });
+
+  {
+    std::lock_guard<std::mutex> guard(mStateMutex);
+    mState = HalState::ONE_CLIENT;
+  }
+  ALOGI("initialization complete");
+  auto status = mCb->initializationComplete(Status::SUCCESS);
+  if (!status.isOk()) {
+    if (!mDeathRecipient->getHasDied()) {
+      ALOGE("Error sending init callback, but no death notification");
+    }
+    close();
+    return ndk::ScopedAStatus::fromServiceSpecificError(
+        STATUS_FAILED_TRANSACTION);
+  }
+
+  return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus BluetoothHci::close() {
+  ALOGI(__func__);
+  {
+    std::lock_guard<std::mutex> guard(mStateMutex);
+    if (mState != HalState::ONE_CLIENT) {
+      LOG_ALWAYS_FATAL_IF(mState == HalState::INITIALIZING,
+                          "mState is INITIALIZING");
+      ALOGI("Already closed");
+      return ndk::ScopedAStatus::ok();
+    }
+    mState = HalState::CLOSING;
+  }
+
+  mFdWatcher.StopWatchingFileDescriptors();
+
+  if (management_) {
+    management_->closeHci();
+  } else {
+    ::close(mFd);
+  }
+
+  {
+    std::lock_guard<std::mutex> guard(mStateMutex);
+    mState = HalState::READY;
+    mH4 = nullptr;
+  }
+  return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus BluetoothHci::sendHciCommand(
+    const std::vector<uint8_t>& packet) {
+  return send(PacketType::COMMAND, packet);
+}
+
+ndk::ScopedAStatus BluetoothHci::sendAclData(
+    const std::vector<uint8_t>& packet) {
+  return send(PacketType::ACL_DATA, packet);
+}
+
+ndk::ScopedAStatus BluetoothHci::sendScoData(
+    const std::vector<uint8_t>& packet) {
+  return send(PacketType::SCO_DATA, packet);
+}
+
+ndk::ScopedAStatus BluetoothHci::sendIsoData(
+    const std::vector<uint8_t>& packet) {
+  return send(PacketType::ISO_DATA, packet);
+}
+
+ndk::ScopedAStatus BluetoothHci::send(PacketType type,
+    const std::vector<uint8_t>& v) {
+  if (v.empty()) {
+    ALOGE("Packet is empty, no data was found to be sent");
+    return ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_ARGUMENT);
+  }
+
+  std::lock_guard<std::mutex> guard(mStateMutex);
+  if (mH4 == nullptr) {
+    return ndk::ScopedAStatus::fromExceptionCode(EX_ILLEGAL_STATE);
+  }
+
+  mH4->Send(type, v);
+  return ndk::ScopedAStatus::ok();
+}
+
+}  // namespace aidl::android::hardware::bluetooth::impl

bluetooth/BluetoothHci.h

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <aidl/android/hardware/bluetooth/BnBluetoothHci.h>
+#include <aidl/android/hardware/bluetooth/IBluetoothHciCallbacks.h>
+
+#include <future>
+#include <string>
+
+#include "async_fd_watcher.h"
+#include "h4_protocol.h"
+#include "net_bluetooth_mgmt.h"
+
+namespace aidl::android::hardware::bluetooth::impl {
+
+class BluetoothDeathRecipient;
+
+// This Bluetooth HAL implementation connects with a serial port at dev_path_.
+class BluetoothHci : public BnBluetoothHci {
+ public:
+  BluetoothHci(const std::string& dev_path = "/dev/hvc5");
+
+  ndk::ScopedAStatus initialize(
+      const std::shared_ptr<IBluetoothHciCallbacks>& cb) override;
+
+  ndk::ScopedAStatus sendHciCommand(
+      const std::vector<uint8_t>& packet) override;
+
+  ndk::ScopedAStatus sendAclData(const std::vector<uint8_t>& packet) override;
+
+  ndk::ScopedAStatus sendScoData(const std::vector<uint8_t>& packet) override;
+
+  ndk::ScopedAStatus sendIsoData(const std::vector<uint8_t>& packet) override;
+
+  ndk::ScopedAStatus close() override;
+
+  static void OnPacketReady();
+
+  static BluetoothHci* get();
+
+ private:
+  int mFd{-1};
+  std::shared_ptr<IBluetoothHciCallbacks> mCb = nullptr;
+
+  std::shared_ptr<::android::hardware::bluetooth::hci::H4Protocol> mH4;
+
+  std::shared_ptr<BluetoothDeathRecipient> mDeathRecipient;
+
+  std::string mDevPath;
+
+  ::android::hardware::bluetooth::async::AsyncFdWatcher mFdWatcher;
+
+  int getFdFromDevPath();
+  [[nodiscard]] ndk::ScopedAStatus send(
+      ::android::hardware::bluetooth::hci::PacketType type,
+      const std::vector<uint8_t>& packet);
+  std::unique_ptr<NetBluetoothMgmt> management_{};
+
+  // Send a reset command and discard all packets until a reset is received.
+  void reset();
+
+  // Don't close twice or open before close is complete
+  std::mutex mStateMutex;
+  enum class HalState {
+    READY,
+    INITIALIZING,
+    ONE_CLIENT,
+    CLOSING,
+  } mState{HalState::READY};
+};
+
+}  // namespace aidl::android::hardware::bluetooth::impl

bluetooth/bluetooth-service-default.rc

@@ -0,0 +1,6 @@
+service vendor.bluetooth-default /vendor/bin/hw/android.hardware.bluetooth-service.default
+    class hal
+    capabilities BLOCK_SUSPEND NET_ADMIN SYS_NICE
+    user bluetooth
+    group bluetooth
+    task_profiles HighPerformance

bluetooth/bluetooth-service-default.xml

@@ -0,0 +1,6 @@
+<manifest version="1.0" type="device">
+    <hal format="aidl">
+        <name>android.hardware.bluetooth</name>
+        <fqname>IBluetoothHci/default</fqname>
+    </hal>
+</manifest>

bluetooth/net_bluetooth_mgmt.cpp

@@ -0,0 +1,307 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "android.hardware.bluetooth.service.default"
+
+#include "net_bluetooth_mgmt.h"
+
+#include <fcntl.h>
+#include <log/log.h>
+#include <poll.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include <cerrno>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+
+// Definitions imported from <linux/net/bluetooth/bluetooth.h>
+#define BTPROTO_HCI 1
+
+// Definitions imported from <linux/net/bluetooth/hci_sock.h>
+#define HCI_CHANNEL_USER 1
+#define HCI_CHANNEL_CONTROL 3
+#define HCI_DEV_NONE 0xffff
+
+struct sockaddr_hci {
+  sa_family_t hci_family;
+  unsigned short hci_dev;
+  unsigned short hci_channel;
+};
+
+// Definitions imported from <linux/net/bluetooth/mgmt.h>
+#define MGMT_OP_READ_INDEX_LIST 0x0003
+#define MGMT_EV_INDEX_ADDED 0x0004
+#define MGMT_EV_CMD_COMPLETE 0x0001
+#define MGMT_PKT_SIZE_MAX 1024
+#define MGMT_INDEX_NONE 0xFFFF
+
+struct mgmt_pkt {
+  uint16_t opcode;
+  uint16_t index;
+  uint16_t len;
+  uint8_t data[MGMT_PKT_SIZE_MAX];
+} __attribute__((packed));
+
+struct mgmt_ev_read_index_list {
+  uint16_t opcode;
+  uint8_t status;
+  uint16_t num_controllers;
+  uint16_t index[];
+} __attribute__((packed));
+
+// Definitions imported from <linux/rfkill.h>
+#define RFKILL_STATE_SOFT_BLOCKED 0
+#define RFKILL_STATE_UNBLOCKED 1
+#define RFKILL_STATE_HARD_BLOCKED 2
+
+#define RFKILL_TYPE_BLUETOOTH 2
+
+#define RFKILL_OP_ADD 0
+#define RFKILL_OP_CHANGE 2
+
+struct rfkill_event {
+  uint32_t idx;
+  uint8_t type;
+  uint8_t op;
+  uint8_t soft;
+  uint8_t hard;
+} __attribute__((packed));
+
+namespace aidl::android::hardware::bluetooth::impl {
+
+// Wait indefinitely for the selected HCI interface to be enabled in the
+// bluetooth driver.
+int NetBluetoothMgmt::waitHciDev(int hci_interface) {
+  ALOGI("waiting for hci interface %d", hci_interface);
+
+  int ret = -1;
+  struct mgmt_pkt cmd;
+  struct pollfd pollfd;
+  struct sockaddr_hci hci_addr = {
+      .hci_family = AF_BLUETOOTH,
+      .hci_dev = HCI_DEV_NONE,
+      .hci_channel = HCI_CHANNEL_CONTROL,
+  };
+
+  // Open and bind a socket to the bluetooth control interface in the
+  // kernel driver, used to send control commands and receive control
+  // events.
+  int fd = socket(PF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
+  if (fd < 0) {
+    ALOGE("unable to open raw bluetooth socket: %s", strerror(errno));
+    return -1;
+  }
+
+  if (bind(fd, (struct sockaddr*)&hci_addr, sizeof(hci_addr)) < 0) {
+    ALOGE("unable to bind bluetooth control channel: %s", strerror(errno));
+    goto end;
+  }
+
+  // Send the control command [Read Index List].
+  cmd = {
+      .opcode = MGMT_OP_READ_INDEX_LIST,
+      .index = MGMT_INDEX_NONE,
+      .len = 0,
+  };
+
+  if (write(fd, &cmd, 6) != 6) {
+    ALOGE("error writing mgmt command: %s", strerror(errno));
+    goto end;
+  }
+
+  // Poll the control socket waiting for the command response,
+  // and subsequent [Index Added] events. The loops continue without
+  // timeout until the selected hci interface is detected.
+  pollfd = {.fd = fd, .events = POLLIN};
+
+  for (;;) {
+    ret = poll(&pollfd, 1, -1);
+
+    // Poll interrupted, try again.
+    if (ret == -1 && (errno == EINTR || errno == EAGAIN)) {
+      continue;
+    }
+
+    // Poll failure, abandon.
+    if (ret == -1) {
+      ALOGE("poll error: %s", strerror(errno));
+      break;
+    }
+
+    // Spurious wakeup, try again.
+    if (ret == 0 || (pollfd.revents & POLLIN) == 0) {
+      continue;
+    }
+
+    // Read the next control event.
+    struct mgmt_pkt ev {};
+    ret = read(fd, &ev, sizeof(ev));
+    if (ret < 0) {
+      ALOGE("error reading mgmt event: %s", strerror(errno));
+      goto end;
+    }
+
+    // Received [Read Index List] command response.
+    if (ev.opcode == MGMT_EV_CMD_COMPLETE) {
+      struct mgmt_ev_read_index_list* data =
+          (struct mgmt_ev_read_index_list*)ev.data;
+
+      // Prefer the exact hci_interface
+      for (int i = 0; i < data->num_controllers; i++) {
+        if (data->index[i] == hci_interface) {
+          ALOGI("hci interface %d found", data->index[i]);
+          ret = data->index[i];
+          goto end;
+        }
+      }
+
+      // Accept a larger one if we can't find the exact one
+      for (int i = 0; i < data->num_controllers; i++) {
+        if (data->index[i] >= hci_interface) {
+          ALOGI("hci interface %d found", data->index[i]);
+          ret = data->index[i];
+          goto end;
+        }
+      }
+    }
+
+    // Received [Index Added] event.
+    if (ev.opcode == MGMT_EV_INDEX_ADDED && ev.index == hci_interface) {
+      ALOGI("hci interface %d added", hci_interface);
+      ret = hci_interface;
+      goto end;
+    }
+  }
+
+end:
+  ::close(fd);
+  return ret;
+}
+
+int NetBluetoothMgmt::openRfkill() {
+  int fd = open("/dev/rfkill", O_RDWR);
+  if (fd < 0) {
+    ALOGE("unable to open /dev/rfkill: %s", strerror(errno));
+    return -1;
+  }
+
+  if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) {
+    ALOGE("unable to set rfkill control device to non-blocking: %s",
+          strerror(errno));
+    ::close(fd);
+    return -1;
+  }
+
+  for (;;) {
+    struct rfkill_event event {};
+    ssize_t res = read(fd, &event, sizeof(event));
+    if (res < 0) {
+      ALOGE("error reading rfkill events: %s", strerror(errno));
+      break;
+    }
+
+    ALOGI("index:%d type:%d op:%d", event.idx, event.type, event.op);
+
+    if (event.op == RFKILL_OP_ADD && event.type == RFKILL_TYPE_BLUETOOTH) {
+      rfkill_bt_index_ = event.idx;
+      rfkill_fd_ = fd;
+      return 0;
+    }
+  }
+
+  ::close(fd);
+  return -1;
+}
+
+// Block or unblock Bluetooth.
+int NetBluetoothMgmt::rfkill(int block) {
+  if (rfkill_fd_ == -1) {
+    openRfkill();
+  }
+
+  if (rfkill_fd_ == -1) {
+    ALOGE("rfkill unavailable");
+    return -1;
+  }
+
+  struct rfkill_event event = {
+      .idx = static_cast<uint32_t>(rfkill_bt_index_),
+      .type = RFKILL_TYPE_BLUETOOTH,
+      .op = RFKILL_OP_CHANGE,
+      .soft = static_cast<uint8_t>(block),
+      .hard = 0,
+  };
+
+  int res = write(rfkill_fd_, &event, sizeof(event));
+  if (res < 0) {
+    ALOGE("error writing rfkill command: %s", strerror(errno));
+    return -1;
+  }
+
+  return 0;
+}
+
+int NetBluetoothMgmt::openHci(int hci_interface) {
+  ALOGI("opening hci interface %d", hci_interface);
+
+  // Block Bluetooth.
+  rfkill(1);
+
+  // Wait for the HCI interface to complete initialization or to come online.
+  int hci = waitHciDev(hci_interface);
+  if (hci < 0) {
+    ALOGE("hci interface %d not found", hci_interface);
+    return -1;
+  }
+
+  // Open the raw HCI socket.
+  int fd = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
+  if (fd < 0) {
+    ALOGE("unable to open raw bluetooth socket: %s", strerror(errno));
+    return -1;
+  }
+
+  struct sockaddr_hci hci_addr = {
+      .hci_family = AF_BLUETOOTH,
+      .hci_dev = static_cast<uint16_t>(hci),
+      .hci_channel = HCI_CHANNEL_USER,
+  };
+
+  // Bind the socket to the selected interface.
+  if (bind(fd, (struct sockaddr*)&hci_addr, sizeof(hci_addr)) < 0) {
+    ALOGE("unable to bind bluetooth user channel: %s", strerror(errno));
+    ::close(fd);
+    return -1;
+  }
+
+  ALOGI("hci interface %d ready", hci);
+  bt_fd_ = fd;
+  return fd;
+}
+
+void NetBluetoothMgmt::closeHci() {
+  if (bt_fd_ != -1) {
+    ::close(bt_fd_);
+    bt_fd_ = -1;
+  }
+
+  // Unblock Bluetooth.
+  rfkill(0);
+}
+
+}  // namespace aidl::android::hardware::bluetooth::impl

bluetooth/net_bluetooth_mgmt.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <unistd.h>
+
+namespace aidl::android::hardware::bluetooth::impl {
+
+class NetBluetoothMgmt {
+ public:
+  NetBluetoothMgmt() {}
+  ~NetBluetoothMgmt() {
+    ::close(rfkill_fd_);
+    ::close(bt_fd_);
+  }
+
+  int openHci(int hci_interface = 0);
+  void closeHci();
+
+ private:
+  int waitHciDev(int hci_interface);
+  int openRfkill();
+  int rfkill(int block);
+
+  // Index of the first rfkill device of type bluetooth.
+  int rfkill_bt_index_{-1};
+  // File descriptor opened to /dev/rfkill.
+  int rfkill_fd_{-1};
+  // File descriptor opened to the bluetooth user channel.
+  int bt_fd_{-1};
+};
+
+}  // namespace aidl::android::hardware::bluetooth::impl

bluetooth/service.cpp

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "aidl.android.hardware.bluetooth.service.default"
+
+#include <aidl/android/hardware/bluetooth/IBluetoothHci.h>
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+#include <hidl/HidlSupport.h>
+#include <hidl/HidlTransportSupport.h>
+
+#include "BluetoothHci.h"
+
+using ::aidl::android::hardware::bluetooth::impl::BluetoothHci;
+using ::android::hardware::configureRpcThreadpool;
+using ::android::hardware::joinRpcThreadpool;
+
+int main(int /* argc */, char** /* argv */) {
+  ALOGI("Bluetooth HAL starting");
+  if (!ABinderProcess_setThreadPoolMaxThreadCount(0)) {
+    ALOGI("failed to set thread pool max thread count");
+    return 1;
+  }
+
+  std::shared_ptr<BluetoothHci> service =
+      ndk::SharedRefBase::make<BluetoothHci>();
+  std::string instance = std::string() + BluetoothHci::descriptor + "/default";
+  auto result =
+      AServiceManager_addService(service->asBinder().get(), instance.c_str());
+  if (result == STATUS_OK) {
+    ABinderProcess_joinThreadPool();
+  } else {
+    ALOGE("Could not register as a service!");
+  }
+  return 0;
+}