nearby/internal/platform/awdl.cc

// Copyright 2025 Google LLC
//
// 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
//
//     https://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 "internal/platform/awdl.h"

#include <memory>
#include <string>
#include <utility>

#include "absl/container/flat_hash_map.h"
#include "absl/container/flat_hash_set.h"
#include "internal/platform/cancellation_flag.h"
#include "internal/platform/implementation/awdl.h"
#include "internal/platform/implementation/psk_info.h"
#include "internal/platform/logging.h"
#include "internal/platform/mutex_lock.h"
#include "internal/platform/nsd_service_info.h"
#include "internal/platform/output_stream.h"
#include "internal/platform/socket.h"

namespace nearby {
using location::nearby::proto::connections::Medium;

MediumSocket* AwdlSocket::CreateVirtualSocket(
    const std::string& salted_service_id_hash_key, OutputStream* outputstream,
    Medium medium,
    absl::flat_hash_map<std::string, std::shared_ptr<MediumSocket>>*
        virtual_sockets_ptr) {
  if (IsVirtualSocket()) {
    LOG(WARNING)
        << "Creating the virtual socket on a virtual socket is not allowed.";
    return nullptr;
  }

  auto virtual_socket = std::make_shared<AwdlSocket>(outputstream);
  virtual_socket->impl_ = this->impl_;
  LOG(WARNING) << "Created the virtual socket for Medium: "
               << Medium_Name(virtual_socket->GetMedium());

  if (virtual_sockets_ptr_ == nullptr) {
    virtual_sockets_ptr_ = virtual_sockets_ptr;
  }

  (*virtual_sockets_ptr_)[salted_service_id_hash_key] = virtual_socket;
  LOG(INFO) << "virtual_sockets_ size: " << virtual_sockets_ptr_->size();
  return virtual_socket.get();
}

bool AwdlMedium::StartAdvertising(const NsdServiceInfo& nsd_service_info) {
  return impl_->StartAdvertising(nsd_service_info);
}

bool AwdlMedium::StopAdvertising(const NsdServiceInfo& nsd_service_info) {
  return impl_->StopAdvertising(nsd_service_info);
}

bool AwdlMedium::StartDiscovery(const std::string& service_id,
                                const std::string& service_type,
                                DiscoveredServiceCallback callback) {
  {
    MutexLock lock(&mutex_);
    if (service_type_to_callback_map_.contains(service_type)) {
      LOG(INFO) << "Awdl Discovery already start with service_type="
                << service_type << "; impl=" << &GetImpl();
      return false;
    }
  }
  api::AwdlMedium::DiscoveredServiceCallback api_callback = {
      .service_discovered_cb =
          [this](const NsdServiceInfo& service_info) {
            MutexLock lock(&mutex_);
            std::string service_type = service_info.GetServiceType();
            // Check callback for the service type.
            const auto& it = service_type_to_callback_map_.find(service_type);

            if (it == service_type_to_callback_map_.end()) {
              LOG(ERROR) << "There is no callback found for service_type="
                         << service_type;
              return;
            }

            // Check whether service name is in cache.
            auto services_it = service_type_to_services_map_.find(service_type);
            if (services_it == service_type_to_services_map_.end()) {
              LOG(ERROR) << "There is no service map found for service_type="
                         << service_type;
              return;
            }

            std::string service_name = service_info.GetServiceName();
            auto pair = services_it->second.insert(service_name);
            if (!pair.second) {
              LOG(INFO) << "Discovering (again) service_info=" << &service_info
                        << ", service_type=" << service_type
                        << ", service_name=" << service_info.GetServiceName();
              return;
            }

            LOG(INFO) << "Adding service_info=" << &service_info
                      << ", service_type=" << service_type
                      << ", service_name=" << service_info.GetServiceName();

            std::string service_id = it->second->service_id;
            DiscoveredServiceCallback& medium_callback =
                it->second->medium_callback;
            medium_callback.service_discovered_cb(service_info, service_id);
          },
      .service_lost_cb =
          [this](const NsdServiceInfo& service_info) {
            MutexLock lock(&mutex_);
            std::string service_type = service_info.GetServiceType();
            std::string service_name = service_info.GetServiceName();
            auto services_it = service_type_to_services_map_.find(service_type);
            if (services_it == service_type_to_services_map_.end()) {
              LOG(ERROR) << "There is no service map found for service_type="
                         << service_type;
              return;
            }

            auto item = services_it->second.extract(service_name);
            if (item.empty()) return;
            LOG(INFO) << "Removing service_info=" << &service_info
                      << ", service_type=" << service_type
                      << ", service_info_name=" << service_name;
            // Callback service lost.
            const auto& it = service_type_to_callback_map_.find(service_type);
            if (it != service_type_to_callback_map_.end()) {
              std::string service_id = it->second->service_id;
              DiscoveredServiceCallback& medium_callback =
                  it->second->medium_callback;
              medium_callback.service_lost_cb(service_info, service_id);
            }
          },
  };
  {
    // Insert callback to the map first no matter it succeeds or not.
    MutexLock lock(&mutex_);
    auto pair = service_type_to_callback_map_.insert(
        {service_type, std::make_unique<DiscoveryCallbackInfo>()});
    auto& context = *pair.first->second;
    context.medium_callback = std::move(callback);
    context.service_id = service_id;

    // Insert an empty services set to track the services under the service
    // type.
    service_type_to_services_map_.insert(
        {service_type, absl::flat_hash_set<std::string>()});
  }

  bool success = impl_->StartDiscovery(service_type, std::move(api_callback));
  if (!success) {
    // If failed, then revert back the insertion.
    MutexLock lock(&mutex_);
    service_type_to_callback_map_.erase(service_type);
    service_type_to_services_map_.erase(service_type);
  }
  LOG(INFO) << "Awdl Discovery started for service_type=" << service_type
            << ", impl=" << &GetImpl() << ", success=" << success;
  return success;
}

bool AwdlMedium::StopDiscovery(const std::string& service_type) {
  MutexLock lock(&mutex_);
  if (!service_type_to_callback_map_.contains(service_type)) {
    return false;
  }
  service_type_to_callback_map_.erase(service_type);
  if (service_type_to_services_map_.contains(service_type)) {
    service_type_to_services_map_.erase(service_type);
  }
  LOG(INFO) << "Awdl Discovery disabled for service_type=" << service_type
            << ", impl=" << &GetImpl();
  return impl_->StopDiscovery(service_type);
}

AwdlSocket AwdlMedium::ConnectToService(
    const NsdServiceInfo& remote_service_info,
    CancellationFlag* cancellation_flag) {
  LOG(INFO) << "AwdlMedium::ConnectToService {service_name="
            << remote_service_info.GetServiceName()
            << ", service_type=" << remote_service_info.GetServiceType() << "}";
  return AwdlSocket(
      impl_->ConnectToService(remote_service_info, cancellation_flag));
}

AwdlSocket AwdlMedium::ConnectToService(
    const NsdServiceInfo& remote_service_info, const api::PskInfo& psk_info,
    CancellationFlag* cancellation_flag) {
  LOG(INFO) << "AwdlMedium::ConnectToService using PSK {service_name="
            << remote_service_info.GetServiceName()
            << ", service_type=" << remote_service_info.GetServiceType()
            << "} using PSK";
  return AwdlSocket(impl_->ConnectToService(remote_service_info, psk_info,
                                            cancellation_flag));
}

}  // namespace nearby