bluetooth/hci/h4_protocol.cc

/*
 * 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.
 */

#include "h4_protocol.h"

#define LOG_TAG "android.hardware.bluetooth.hci-h4"

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/uio.h>

#include "log/log.h"

namespace android::hardware::bluetooth::hci {

H4Protocol::H4Protocol(int fd, PacketReadCallback cmd_cb,
                       PacketReadCallback acl_cb, PacketReadCallback sco_cb,
                       PacketReadCallback event_cb, PacketReadCallback iso_cb,
                       DisconnectCallback disconnect_cb)
    : uart_fd_(fd),
      cmd_cb_(std::move(cmd_cb)),
      acl_cb_(std::move(acl_cb)),
      sco_cb_(std::move(sco_cb)),
      event_cb_(std::move(event_cb)),
      iso_cb_(std::move(iso_cb)),
      disconnect_cb_(std::move(disconnect_cb)) {}

size_t H4Protocol::Send(PacketType type, const std::vector<uint8_t>& vector) {
  return Send(type, vector.data(), vector.size());
}

size_t H4Protocol::Send(PacketType type, const uint8_t* data, size_t length) {
  struct iovec iov_array[] = {{&type, sizeof(type)},
                              {const_cast<uint8_t*>(data), length}};
  size_t iovcnt = sizeof(iov_array) / sizeof(iov_array[0]);
  struct iovec* iov = iov_array;
  size_t total_bytes = sizeof(type) + length;
  size_t remaining_bytes = total_bytes;
  size_t bytes_written = 0;

  while (remaining_bytes > 0) {
    ssize_t ret = TEMP_FAILURE_RETRY(writev(uart_fd_, iov, iovcnt));
    if (ret == -1) {
      if (errno == EAGAIN) continue;
      ALOGE("Error writing to UART (%s)", strerror(errno));
      break;
    } else if (ret == 0) {
      // Nothing written :(
      ALOGE("%s zero bytes written - something went wrong...", __func__);
      break;
    } else if (ret == remaining_bytes) {
      // Everything written
      bytes_written += ret;
      break;
    }

    // Updating counters for partial writes
    bytes_written += ret;
    remaining_bytes -= ret;

    ALOGW("%s: %zu/%zu bytes written - retrying remaining %zu bytes", __func__,
          bytes_written, total_bytes, remaining_bytes);

    // Remove fully written iovs from the list
    while (ret >= iov->iov_len) {
      ret -= iov->iov_len;
      ++iov;
      --iovcnt;
    }
    // Adjust the iov to point to the remaining data that needs to be written
    if (ret > 0) {
      iov->iov_base = static_cast<uint8_t*>(iov->iov_base) + ret;
      iov->iov_len -= ret;
    }
  }
  return total_bytes - remaining_bytes;
}

size_t H4Protocol::OnPacketReady(const std::vector<uint8_t>& packet) {
  switch (hci_packet_type_) {
    case PacketType::COMMAND:
      cmd_cb_(packet);
      break;
    case PacketType::ACL_DATA:
      acl_cb_(packet);
      break;
    case PacketType::SCO_DATA:
      sco_cb_(packet);
      break;
    case PacketType::EVENT:
      event_cb_(packet);
      break;
    case PacketType::ISO_DATA:
      iso_cb_(packet);
      break;
    default: {
      LOG_ALWAYS_FATAL("Bad packet type 0x%x",
                       static_cast<int>(hci_packet_type_));
    }
  }
  return packet.size();
}

void H4Protocol::SendDataToPacketizer(uint8_t* buffer, size_t length) {
  std::vector<uint8_t> input_buffer{buffer, buffer + length};
  size_t buffer_offset = 0;
  while (buffer_offset < input_buffer.size()) {
    if (hci_packet_type_ == PacketType::UNKNOWN) {
      hci_packet_type_ =
          static_cast<PacketType>(input_buffer.data()[buffer_offset]);
      buffer_offset += 1;
    } else {
      bool packet_ready = hci_packetizer_.OnDataReady(
          hci_packet_type_, input_buffer, &buffer_offset);
      if (packet_ready) {
        // Call packet callback.
        OnPacketReady(hci_packetizer_.GetPacket());
        // Get ready for the next type byte.
        hci_packet_type_ = PacketType::UNKNOWN;
      }
    }
  }
}

void H4Protocol::OnDataReady() {
  if (disconnected_) {
    return;
  }
  uint8_t buffer[kMaxPacketLength];
  ssize_t bytes_read =
      TEMP_FAILURE_RETRY(read(uart_fd_, buffer, kMaxPacketLength));
  if (bytes_read == 0) {
    ALOGI("No bytes read, calling the disconnect callback");
    disconnected_ = true;
    disconnect_cb_();
    return;
  }
  if (bytes_read < 0) {
    ALOGW("error reading from UART (%s)", strerror(errno));
    return;
  }
  SendDataToPacketizer(buffer, bytes_read);
}

}  // namespace android::hardware::bluetooth::hci