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Commit 76ff302d authored by Roshan Pius's avatar Roshan Pius
Browse files

wifi: Add gscan API wrappers in WifiLegacyHal 

The legacy gscan API's were designed to be used in the following
sequence:
a) Start the scan using |wifi_start_gscan|.
b) Scan Events are indicated to the caller via the provided
|on_scan_event| callback.
c) When one of the result events are received, the caller is expected
to retrieve the cached results via |wifi_get_cached_gscan_results|.
There are some extra knobs here to determine if the results need to be
flushed after fetch or not.
d) Any scan failures are also notified via the provided
|on_scan_event| callback.
e) Full scan results are delivered one by one via the provided
|on_full_scan_result| callback.

In our use case step (b) above is always followed by step (c), so these
2 steps have been merged together in the HIDL interface:
a) Start the scan using |IWifiStaIface.startBackgroundScan|.
b) Scan results are now directly delivered via
|IWifiStaIfaceEventCallback.onBackgroundScanResults| callback.
c) Any scan failures will be delivered via
|IWifiStaIfaceEventCallback.onBackgroundScanFailure| callback.
d) Full scan results are delivered one by one via
|IWifiStaIfaceEventCallback.onBackgroundFullScanResult| callback.

Bug: 31991459
Test: Compiles
Change-Id: I0870eae095a667eec1d8de75fe1cc04a1b5a0bd3
parent 63544eac

wifi/1.0/default/wifi_legacy_hal.cpp

+161 −1
Original line number Diff line number Diff line
@@ -28,8 +28,13 @@ namespace wifi { 
namespace V1_0 {

namespace implementation {

namespace legacy_hal {

// Constants used in the class.

// Constants ported over from the legacy HAL calling code

// (com_android_server_wifi_WifiNative.cpp). This will all be thrown

// away when this shim layer is replaced by the real vendor

// implementation.

static constexpr uint32_t kMaxVersionStringLength = 256;

static constexpr uint32_t kMaxCachedGscanResults = 64;

static constexpr uint32_t kMaxGscanFrequenciesForBand = 64;



// Legacy HAL functions accept "C" style function pointers, so use global

// functions to pass to the legacy HAL function and store the corresponding
@@ -57,6 +62,27 @@ void onFirmwareMemoryDump(char* buffer, int buffer_size) { 
    on_firmware_memory_dump_internal_callback(buffer, buffer_size);

  }

}



// Callback to be invoked for Gscan events.

std::function<void(wifi_request_id, wifi_scan_event)>

    on_gscan_event_internal_callback;

void onGscanEvent(wifi_request_id id, wifi_scan_event event) {

  if (on_gscan_event_internal_callback) {

    on_gscan_event_internal_callback(id, event);

  }

}



// Callback to be invoked for Gscan full results.

std::function<void(wifi_request_id, wifi_scan_result*, uint32_t)>

    on_gscan_full_result_internal_callback;

void onGscanFullResult(wifi_request_id id,

                       wifi_scan_result* result,

                       uint32_t buckets_scanned) {

  if (on_gscan_full_result_internal_callback) {

    on_gscan_full_result_internal_callback(id, result, buckets_scanned);

  }

}



// End of the free-standing "C" style callbacks.



WifiLegacyHal::WifiLegacyHal()
@@ -206,6 +232,109 @@ wifi_error WifiLegacyHal::setPacketFilter(const std::vector<uint8_t>& program) { 
      wlan_interface_handle_, program.data(), program.size());

}



std::pair<wifi_error, wifi_gscan_capabilities>

WifiLegacyHal::getGscanCapabilities() {

  wifi_gscan_capabilities caps;

  wifi_error status = global_func_table_.wifi_get_gscan_capabilities(

      wlan_interface_handle_, &caps);

  return {status, caps};

}



wifi_error WifiLegacyHal::startGscan(

    wifi_request_id id,

    const wifi_scan_cmd_params& params,

    const std::function<void(wifi_request_id)>& on_failure_user_callback,

    const on_gscan_results_callback& on_results_user_callback,

    const on_gscan_full_result_callback& on_full_result_user_callback) {

  // If there is already an ongoing background scan, reject new scan requests.

  if (on_gscan_event_internal_callback ||

      on_gscan_full_result_internal_callback) {

    return WIFI_ERROR_NOT_AVAILABLE;

  }



  // This callback will be used to either trigger |on_results_user_callback| or

  // |on_failure_user_callback|.

  on_gscan_event_internal_callback =

      [on_failure_user_callback, on_results_user_callback, this](

          wifi_request_id id, wifi_scan_event event) {

        switch (event) {

          case WIFI_SCAN_RESULTS_AVAILABLE:

          case WIFI_SCAN_THRESHOLD_NUM_SCANS:

          case WIFI_SCAN_THRESHOLD_PERCENT: {

            wifi_error status;

            std::vector<wifi_cached_scan_results> cached_scan_results;

            std::tie(status, cached_scan_results) = getGscanCachedResults();

            if (status == WIFI_SUCCESS) {

              on_results_user_callback(id, cached_scan_results);

              return;

            }

          }

          // Fall through if failed. Failure to retrieve cached scan results

          // should trigger a background scan failure.

          case WIFI_SCAN_FAILED:

            on_failure_user_callback(id);

            on_gscan_event_internal_callback = nullptr;

            on_gscan_full_result_internal_callback = nullptr;

            return;

        }

        LOG(FATAL) << "Unexpected gscan event received: " << event;

      };



  on_gscan_full_result_internal_callback = [on_full_result_user_callback](

      wifi_request_id id, wifi_scan_result* result, uint32_t buckets_scanned) {

    if (result) {

      on_full_result_user_callback(id, result, buckets_scanned);

    }

  };



  wifi_scan_result_handler handler = {onGscanFullResult, onGscanEvent};

  wifi_error status = global_func_table_.wifi_start_gscan(

      id, wlan_interface_handle_, params, handler);

  if (status != WIFI_SUCCESS) {

    on_gscan_event_internal_callback = nullptr;

    on_gscan_full_result_internal_callback = nullptr;

  }

  return status;

}



wifi_error WifiLegacyHal::stopGscan(wifi_request_id id) {

  // If there is no an ongoing background scan, reject stop requests.

  // TODO(b/32337212): This needs to be handled by the HIDL object because we

  // need to return the NOT_STARTED error code.

  if (!on_gscan_event_internal_callback &&

      !on_gscan_full_result_internal_callback) {

    return WIFI_ERROR_NOT_AVAILABLE;

  }

  wifi_error status =

      global_func_table_.wifi_stop_gscan(id, wlan_interface_handle_);

  // If the request Id is wrong, don't stop the ongoing background scan. Any

  // other error should be treated as the end of background scan.

  if (status != WIFI_ERROR_INVALID_REQUEST_ID) {

    on_gscan_event_internal_callback = nullptr;

    on_gscan_full_result_internal_callback = nullptr;

  }

  return status;

}



std::pair<wifi_error, std::vector<uint32_t>>

WifiLegacyHal::getValidFrequenciesForGscan(wifi_band band) {

  static_assert(sizeof(uint32_t) >= sizeof(wifi_channel),

                "Wifi Channel cannot be represented in output");

  std::vector<uint32_t> freqs;

  freqs.resize(kMaxGscanFrequenciesForBand);

  int32_t num_freqs = 0;

  wifi_error status = global_func_table_.wifi_get_valid_channels(

      wlan_interface_handle_,

      band,

      freqs.size(),

      reinterpret_cast<wifi_channel*>(freqs.data()),

      &num_freqs);

  CHECK(num_freqs >= 0 &&

        static_cast<uint32_t>(num_freqs) <= kMaxGscanFrequenciesForBand);

  freqs.resize(num_freqs);

  return {status, std::move(freqs)};

}



wifi_error WifiLegacyHal::retrieveWlanInterfaceHandle() {

  const std::string& ifname_to_find = getStaIfaceName();

  wifi_interface_handle* iface_handles = nullptr;
@@ -245,12 +374,43 @@ void WifiLegacyHal::runEventLoop() { 
  if_tool.SetWifiUpState(false);

}



std::pair<wifi_error, std::vector<wifi_cached_scan_results>>

WifiLegacyHal::getGscanCachedResults() {

  std::vector<wifi_cached_scan_results> cached_scan_results;

  cached_scan_results.resize(kMaxCachedGscanResults);

  int32_t num_results = 0;

  wifi_error status = global_func_table_.wifi_get_cached_gscan_results(

      wlan_interface_handle_,

      true /* always flush */,

      cached_scan_results.size(),

      cached_scan_results.data(),

      &num_results);

  CHECK(num_results >= 0 &&

        static_cast<uint32_t>(num_results) <= kMaxCachedGscanResults);

  cached_scan_results.resize(num_results);

  // Check for invalid IE lengths in these cached scan results and correct it.

  for (auto& cached_scan_result : cached_scan_results) {

    int num_scan_results = cached_scan_result.num_results;

    for (int i = 0; i < num_scan_results; i++) {

      auto& scan_result = cached_scan_result.results[i];

      if (scan_result.ie_length > 0) {

        LOG(ERROR) << "Cached scan result has non-zero IE length "

                   << scan_result.ie_length;

        scan_result.ie_length = 0;

      }

    }

  }

  return {status, std::move(cached_scan_results)};

}



void WifiLegacyHal::invalidate() {

  global_handle_ = nullptr;

  wlan_interface_handle_ = nullptr;

  on_stop_complete_internal_callback = nullptr;

  on_driver_memory_dump_internal_callback = nullptr;

  on_firmware_memory_dump_internal_callback = nullptr;

  on_gscan_event_internal_callback = nullptr;

  on_gscan_full_result_internal_callback = nullptr;

}



}  // namespace legacy_hal

wifi/1.0/default/wifi_legacy_hal.h

+35 −0
Original line number Diff line number Diff line
@@ -39,6 +39,16 @@ struct PacketFilterCapabilities { 
  uint32_t max_len;

};



// Full scan results contain IE info and are hence passed by reference, to

// preserve the variable length array member |ie_data|. Callee must not retain

// the pointer.

using on_gscan_full_result_callback =

    std::function<void(wifi_request_id, const wifi_scan_result*, uint32_t)>;

// These scan results don't contain any IE info, so no need to pass by

// reference.

using on_gscan_results_callback = std::function<void(

    wifi_request_id, const std::vector<wifi_cached_scan_results>&)>;



/**

 * Class that encapsulates all legacy HAL interactions.

 * This class manages the lifetime of the event loop thread used by legacy HAL.
@@ -65,12 +75,37 @@ class WifiLegacyHal { 
  // APF functions.

  std::pair<wifi_error, PacketFilterCapabilities> getPacketFilterCapabilities();

  wifi_error setPacketFilter(const std::vector<uint8_t>& program);

  // Gscan functions.

  std::pair<wifi_error, wifi_gscan_capabilities> getGscanCapabilities();

  // These API's provides a simplified interface over the legacy Gscan API's:

  // a) All scan events from the legacy HAL API other than the

  //    |WIFI_SCAN_FAILED| are treated as notification of results.

  //    This method then retrieves the cached scan results from the legacy

  //    HAL API and triggers the externally provided |on_results_user_callback|

  //    on success.

  // b) |WIFI_SCAN_FAILED| scan event or failure to retrieve cached scan results

  //    triggers the externally provided |on_failure_user_callback|.

  // c) Full scan result event triggers the externally provided

  //    |on_full_result_user_callback|.

  wifi_error startGscan(

      wifi_request_id id,

      const wifi_scan_cmd_params& params,

      const std::function<void(wifi_request_id)>& on_failure_callback,

      const on_gscan_results_callback& on_results_callback,

      const on_gscan_full_result_callback& on_full_result_callback);

  wifi_error stopGscan(wifi_request_id id);

  std::pair<wifi_error, std::vector<uint32_t>> getValidFrequenciesForGscan(

      wifi_band band);



 private:

  // Retrieve the interface handle to be used for the "wlan" interface.

  wifi_error retrieveWlanInterfaceHandle();

  // Run the legacy HAL event loop thread.

  void runEventLoop();

  // Retrieve the cached gscan results to pass the results back to the external

  // callbacks.

  std::pair<wifi_error, std::vector<wifi_cached_scan_results>>

  getGscanCachedResults();

  void invalidate();



  // Event loop thread used by legacy HAL.