// Copyright 2016 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "patchpanel/manager.h"

#include <arpa/inet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdint.h>
#include <sys/epoll.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sys/un.h>

#include <utility>

#include <base/bind.h>
#include <base/files/scoped_file.h>
#include <base/logging.h>
#include <base/strings/string_number_conversions.h>
#include <base/strings/string_split.h>
#include <base/strings/string_util.h>
#include <base/strings/stringprintf.h>
#include <base/threading/thread_task_runner_handle.h>
#include <brillo/key_value_store.h>
#include <brillo/minijail/minijail.h>

#include "patchpanel/ipc.pb.h"
#include "patchpanel/mac_address_generator.h"
#include "patchpanel/net_util.h"
#include "patchpanel/routing_service.h"
#include "patchpanel/scoped_ns.h"

namespace patchpanel {
namespace {
constexpr int kSubprocessRestartDelayMs = 900;

// Time interval between epoll checks on file descriptors committed by callers
// of ConnectNamespace DBus API.
constexpr const base::TimeDelta kConnectNamespaceCheckInterval =
    base::TimeDelta::FromSeconds(5);

// Passes |method_call| to |handler| and passes the response to
// |response_sender|. If |handler| returns nullptr, an empty response is
// created and sent.
void HandleSynchronousDBusMethodCall(
    base::Callback<std::unique_ptr<dbus::Response>(dbus::MethodCall*)> handler,
    dbus::MethodCall* method_call,
    dbus::ExportedObject::ResponseSender response_sender) {
  std::unique_ptr<dbus::Response> response = handler.Run(method_call);
  if (!response)
    response = dbus::Response::FromMethodCall(method_call);
  std::move(response_sender).Run(std::move(response));
}

}  // namespace

Manager::Manager(std::unique_ptr<HelperProcess> adb_proxy,
                 std::unique_ptr<HelperProcess> mcast_proxy,
                 std::unique_ptr<HelperProcess> nd_proxy)
    : adb_proxy_(std::move(adb_proxy)),
      mcast_proxy_(std::move(mcast_proxy)),
      nd_proxy_(std::move(nd_proxy)) {
  runner_ = std::make_unique<MinijailedProcessRunner>();
  datapath_ = std::make_unique<Datapath>(runner_.get(), &firewall_);
  connected_namespaces_epollfd_ = epoll_create(1 /* size */);
}

std::map<const std::string, bool> Manager::cached_feature_enabled_ = {};

bool Manager::ShouldEnableFeature(
    int min_android_sdk_version,
    int min_chrome_milestone,
    const std::vector<std::string>& supported_boards,
    const std::string& feature_name) {
  static const char kLsbReleasePath[] = "/etc/lsb-release";

  const auto& cached_result = cached_feature_enabled_.find(feature_name);
  if (cached_result != cached_feature_enabled_.end())
    return cached_result->second;

  auto check = [min_android_sdk_version, min_chrome_milestone,
                &supported_boards, &feature_name]() {
    brillo::KeyValueStore store;
    if (!store.Load(base::FilePath(kLsbReleasePath))) {
      LOG(ERROR) << "Could not read lsb-release";
      return false;
    }

    std::string value;
    if (!store.GetString("CHROMEOS_ARC_ANDROID_SDK_VERSION", &value)) {
      LOG(ERROR) << feature_name
                 << " disabled - cannot determine Android SDK version";
      return false;
    }
    int ver = 0;
    if (!base::StringToInt(value.c_str(), &ver)) {
      LOG(ERROR) << feature_name << " disabled - invalid Android SDK version";
      return false;
    }
    if (ver < min_android_sdk_version) {
      LOG(INFO) << feature_name << " disabled for Android SDK " << value;
      return false;
    }

    if (!store.GetString("CHROMEOS_RELEASE_CHROME_MILESTONE", &value)) {
      LOG(ERROR) << feature_name
                 << " disabled - cannot determine ChromeOS milestone";
      return false;
    }
    if (!base::StringToInt(value.c_str(), &ver)) {
      LOG(ERROR) << feature_name << " disabled - invalid ChromeOS milestone";
      return false;
    }
    if (ver < min_chrome_milestone) {
      LOG(INFO) << feature_name << " disabled for ChromeOS milestone " << value;
      return false;
    }

    if (!store.GetString("CHROMEOS_RELEASE_BOARD", &value)) {
      LOG(ERROR) << feature_name << " disabled - cannot determine board";
      return false;
    }
    if (!supported_boards.empty() &&
        std::find(supported_boards.begin(), supported_boards.end(), value) ==
            supported_boards.end()) {
      LOG(INFO) << feature_name << " disabled for board " << value;
      return false;
    }
    return true;
  };

  bool result = check();
  cached_feature_enabled_.emplace(feature_name, result);
  return result;
}

int Manager::OnInit() {
  prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);

  // Handle subprocess lifecycle.
  process_reaper_.Register(this);

  CHECK(process_reaper_.WatchForChild(
      FROM_HERE, adb_proxy_->pid(),
      base::Bind(&Manager::OnSubprocessExited, weak_factory_.GetWeakPtr(),
                 adb_proxy_->pid())))
      << "Failed to watch adb-proxy child process";
  CHECK(process_reaper_.WatchForChild(
      FROM_HERE, mcast_proxy_->pid(),
      base::Bind(&Manager::OnSubprocessExited, weak_factory_.GetWeakPtr(),
                 nd_proxy_->pid())))
      << "Failed to watch multicast-proxy child process";
  CHECK(process_reaper_.WatchForChild(
      FROM_HERE, nd_proxy_->pid(),
      base::Bind(&Manager::OnSubprocessExited, weak_factory_.GetWeakPtr(),
                 nd_proxy_->pid())))
      << "Failed to watch nd-proxy child process";

  // Run after Daemon::OnInit().
  base::ThreadTaskRunnerHandle::Get()->PostTask(
      FROM_HERE,
      base::Bind(&Manager::InitialSetup, weak_factory_.GetWeakPtr()));

  return DBusDaemon::OnInit();
}

void Manager::InitialSetup() {
  LOG(INFO) << "Setting up DBus service interface";
  dbus_svc_path_ = bus_->GetExportedObject(
      dbus::ObjectPath(patchpanel::kPatchPanelServicePath));
  if (!dbus_svc_path_) {
    LOG(FATAL) << "Failed to export " << patchpanel::kPatchPanelServicePath
               << " object";
  }

  shill_client_ = std::make_unique<ShillClient>(bus_);

  using ServiceMethod =
      std::unique_ptr<dbus::Response> (Manager::*)(dbus::MethodCall*);
  const std::map<const char*, ServiceMethod> kServiceMethods = {
      {patchpanel::kArcStartupMethod, &Manager::OnArcStartup},
      {patchpanel::kArcShutdownMethod, &Manager::OnArcShutdown},
      {patchpanel::kArcVmStartupMethod, &Manager::OnArcVmStartup},
      {patchpanel::kArcVmShutdownMethod, &Manager::OnArcVmShutdown},
      {patchpanel::kTerminaVmStartupMethod, &Manager::OnTerminaVmStartup},
      {patchpanel::kTerminaVmShutdownMethod, &Manager::OnTerminaVmShutdown},
      {patchpanel::kPluginVmStartupMethod, &Manager::OnPluginVmStartup},
      {patchpanel::kPluginVmShutdownMethod, &Manager::OnPluginVmShutdown},
      {patchpanel::kSetVpnIntentMethod, &Manager::OnSetVpnIntent},
      {patchpanel::kConnectNamespaceMethod, &Manager::OnConnectNamespace},
      {patchpanel::kGetTrafficCountersMethod, &Manager::OnGetTrafficCounters},
      {patchpanel::kModifyPortRuleMethod, &Manager::OnModifyPortRule},
      {patchpanel::kGetDevicesMethod, &Manager::OnGetDevices},
  };

  for (const auto& kv : kServiceMethods) {
    if (!dbus_svc_path_->ExportMethodAndBlock(
            patchpanel::kPatchPanelInterface, kv.first,
            base::Bind(&HandleSynchronousDBusMethodCall,
                       base::Bind(kv.second, base::Unretained(this))))) {
      LOG(FATAL) << "Failed to export method " << kv.first;
    }
  }

  if (!bus_->RequestOwnershipAndBlock(patchpanel::kPatchPanelServiceName,
                                      dbus::Bus::REQUIRE_PRIMARY)) {
    LOG(FATAL) << "Failed to take ownership of "
               << patchpanel::kPatchPanelServiceName;
  }
  LOG(INFO) << "DBus service interface ready";

  routing_svc_ = std::make_unique<RoutingService>();
  counters_svc_ =
      std::make_unique<CountersService>(datapath_.get(), runner_.get());

  // b/162966185: Allow Jetstream to disable:
  //  - the IP forwarding setup used for hosting VMs and containers,
  //  - the iptables rules for fwmark based routing.
  if (!USE_JETSTREAM_ROUTING) {
    datapath_->Start();
    shill_client_->RegisterDefaultDeviceChangedHandler(base::BindRepeating(
        &Manager::OnDefaultDeviceChanged, weak_factory_.GetWeakPtr()));
    shill_client_->RegisterDevicesChangedHandler(base::BindRepeating(
        &Manager::OnDevicesChanged, weak_factory_.GetWeakPtr()));
  }

  nd_proxy_->RegisterNDProxyMessageHandler(
      base::Bind(&Manager::OnNDProxyMessage, weak_factory_.GetWeakPtr()));

  auto* const forwarder = static_cast<TrafficForwarder*>(this);

  GuestMessage::GuestType arc_guest =
      USE_ARCVM ? GuestMessage::ARC_VM : GuestMessage::ARC;
  arc_svc_ = std::make_unique<ArcService>(
      shill_client_.get(), datapath_.get(), &addr_mgr_, forwarder, arc_guest,
      base::BindRepeating(&Manager::OnDeviceChanged,
                          weak_factory_.GetWeakPtr()));
  cros_svc_ = std::make_unique<CrostiniService>(
      shill_client_.get(), &addr_mgr_, datapath_.get(), forwarder,
      base::BindRepeating(&Manager::OnDeviceChanged,
                          weak_factory_.GetWeakPtr()));
  network_monitor_svc_ = std::make_unique<NetworkMonitorService>(
      shill_client_.get(),
      base::BindRepeating(&Manager::OnNeighborReachabilityEvent,
                          weak_factory_.GetWeakPtr()));
  network_monitor_svc_->Start();
  counters_svc_->Init(shill_client_->get_devices());
  nd_proxy_->Listen();
}

void Manager::OnShutdown(int* exit_code) {
  LOG(INFO) << "Shutting down and cleaning up";
  network_monitor_svc_.reset();
  cros_svc_.reset();
  arc_svc_.reset();
  close(connected_namespaces_epollfd_);
  // Tear down any remaining connected namespace.
  std::vector<int> connected_namespaces_fdkeys;
  for (const auto& kv : connected_namespaces_)
    connected_namespaces_fdkeys.push_back(kv.first);
  for (const int fdkey : connected_namespaces_fdkeys)
    DisconnectNamespace(fdkey);
  if (!USE_JETSTREAM_ROUTING)
    datapath_->Stop();

  brillo::DBusDaemon::OnShutdown(exit_code);
}

void Manager::OnSubprocessExited(pid_t pid, const siginfo_t&) {
  LOG(ERROR) << "Subprocess " << pid << " exited unexpectedly -"
             << " attempting to restart";

  HelperProcess* proc;
  if (pid == adb_proxy_->pid()) {
    proc = adb_proxy_.get();
  } else if (pid == mcast_proxy_->pid()) {
    proc = mcast_proxy_.get();
  } else if (pid == nd_proxy_->pid()) {
    proc = nd_proxy_.get();
  } else {
    LOG(DFATAL) << "Unknown child process";
    return;
  }

  process_reaper_.ForgetChild(pid);

  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&Manager::RestartSubprocess, weak_factory_.GetWeakPtr(), proc),
      base::TimeDelta::FromMilliseconds((2 << proc->restarts()) *
                                        kSubprocessRestartDelayMs));
}

void Manager::RestartSubprocess(HelperProcess* subproc) {
  if (subproc->Restart()) {
    DCHECK(process_reaper_.WatchForChild(
        FROM_HERE, subproc->pid(),
        base::Bind(&Manager::OnSubprocessExited, weak_factory_.GetWeakPtr(),
                   subproc->pid())))
        << "Failed to watch child process " << subproc->pid();
  }
}

void Manager::OnDefaultDeviceChanged(const ShillClient::Device& new_device,
                                     const ShillClient::Device& prev_device) {
  // Only take into account interface switches and ignore layer 3 property
  // changes.
  if (prev_device.ifname == new_device.ifname)
    return;

  if (prev_device.type == ShillClient::Device::Type::kVPN) {
    datapath_->StopVpnRouting(prev_device.ifname);
    counters_svc_->OnVpnDeviceRemoved(prev_device.ifname);
  }

  if (new_device.type == ShillClient::Device::Type::kVPN) {
    datapath_->StartVpnRouting(new_device.ifname);
    counters_svc_->OnVpnDeviceAdded(new_device.ifname);
  }
}

void Manager::OnDevicesChanged(const std::set<std::string>& added,
                               const std::set<std::string>& removed) {
  for (const std::string& ifname : removed) {
    datapath_->StopConnectionPinning(ifname);
    counters_svc_->OnPhysicalDeviceRemoved(ifname);
  }

  for (const std::string& ifname : added) {
    datapath_->StartConnectionPinning(ifname);
    counters_svc_->OnPhysicalDeviceAdded(ifname);
  }
}

void Manager::OnDeviceChanged(const Device& device,
                              Device::ChangeEvent event,
                              GuestMessage::GuestType guest_type) {
  dbus::Signal signal(kPatchPanelInterface, kNetworkDeviceChangedSignal);
  NetworkDeviceChangedSignal proto;
  proto.set_event(event == Device::ChangeEvent::ADDED
                      ? NetworkDeviceChangedSignal::DEVICE_ADDED
                      : NetworkDeviceChangedSignal::DEVICE_REMOVED);
  auto* dev = proto.mutable_device();
  dev->set_ifname(device.host_ifname());
  dev->set_ipv4_addr(device.config().guest_ipv4_addr());
  if (const auto* subnet = device.config().ipv4_subnet()) {
    auto* sub = dev->mutable_ipv4_subnet();
    sub->set_base_addr(subnet->BaseAddress());
    sub->set_prefix_len(subnet->PrefixLength());
  }
  switch (guest_type) {
    case GuestMessage::ARC:
      dev->set_guest_type(NetworkDevice::ARC);
      break;
    case GuestMessage::ARC_VM:
      dev->set_guest_type(NetworkDevice::ARCVM);
      break;
    case GuestMessage::TERMINA_VM:
      dev->set_guest_type(NetworkDevice::TERMINA_VM);
      break;
    case GuestMessage::PLUGIN_VM:
      dev->set_guest_type(NetworkDevice::PLUGIN_VM);
      break;
    default:
      LOG(ERROR) << "Unknown device type";
  }

  dbus::MessageWriter(&signal).AppendProtoAsArrayOfBytes(proto);
  dbus_svc_path_->SendSignal(&signal);
}

bool Manager::StartArc(pid_t pid) {
  if (!arc_svc_->Start(pid))
    return false;

  GuestMessage msg;
  msg.set_event(GuestMessage::START);
  msg.set_type(GuestMessage::ARC);
  msg.set_arc_pid(pid);
  SendGuestMessage(msg);

  return true;
}

void Manager::StopArc() {
  GuestMessage msg;
  msg.set_event(GuestMessage::STOP);
  msg.set_type(GuestMessage::ARC);
  SendGuestMessage(msg);

  // After the ARC container has stopped, the pid is not known anymore.
  // The pid argument is ignored by ArcService.
  arc_svc_->Stop(0);
}

bool Manager::StartArcVm(uint32_t cid) {
  if (!arc_svc_->Start(cid))
    return false;

  GuestMessage msg;
  msg.set_event(GuestMessage::START);
  msg.set_type(GuestMessage::ARC_VM);
  msg.set_arcvm_vsock_cid(cid);
  SendGuestMessage(msg);

  return true;
}

void Manager::StopArcVm(uint32_t cid) {
  GuestMessage msg;
  msg.set_event(GuestMessage::STOP);
  msg.set_type(GuestMessage::ARC_VM);
  SendGuestMessage(msg);

  arc_svc_->Stop(cid);
}

bool Manager::StartCrosVm(uint64_t vm_id,
                          GuestMessage::GuestType vm_type,
                          uint32_t subnet_index) {
  DCHECK(vm_type == GuestMessage::TERMINA_VM ||
         vm_type == GuestMessage::PLUGIN_VM);

  if (!cros_svc_->Start(vm_id, vm_type == GuestMessage::TERMINA_VM,
                        subnet_index))
    return false;

  GuestMessage msg;
  msg.set_event(GuestMessage::START);
  msg.set_type(vm_type);
  SendGuestMessage(msg);

  return true;
}

void Manager::StopCrosVm(uint64_t vm_id, GuestMessage::GuestType vm_type) {
  GuestMessage msg;
  msg.set_event(GuestMessage::STOP);
  msg.set_type(vm_type);
  SendGuestMessage(msg);

  cros_svc_->Stop(vm_id, vm_type == GuestMessage::TERMINA_VM);
}

std::unique_ptr<dbus::Response> Manager::OnGetDevices(
    dbus::MethodCall* method_call) {
  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::GetDevicesRequest request;
  patchpanel::GetDevicesResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  static const auto arc_guest_type =
      USE_ARCVM ? NetworkDevice::ARCVM : NetworkDevice::ARC;

  arc_svc_->ScanDevices(base::BindRepeating(
      [](patchpanel::GetDevicesResponse* resp, const Device& device) {
        auto* dev = resp->add_devices();
        dev->set_ifname(device.host_ifname());
        dev->set_ipv4_addr(device.config().guest_ipv4_addr());
        dev->set_guest_type(arc_guest_type);
        if (const auto* subnet = device.config().ipv4_subnet()) {
          auto* sub = dev->mutable_ipv4_subnet();
          sub->set_base_addr(subnet->BaseAddress());
          sub->set_prefix_len(subnet->PrefixLength());
        }
      },
      &response));

  cros_svc_->ScanDevices(base::BindRepeating(
      [](patchpanel::GetDevicesResponse* resp, uint64_t vm_id, bool is_termina,
         const Device& device) {
        auto* dev = resp->add_devices();
        dev->set_ifname(device.host_ifname());
        dev->set_ipv4_addr(device.config().guest_ipv4_addr());
        dev->set_guest_type(is_termina ? NetworkDevice::TERMINA_VM
                                       : NetworkDevice::PLUGIN_VM);
        if (const auto* subnet = device.config().ipv4_subnet()) {
          auto* sub = dev->mutable_ipv4_subnet();
          sub->set_base_addr(subnet->BaseAddress());
          sub->set_prefix_len(subnet->PrefixLength());
        }
      },
      &response));

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnArcStartup(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "ARC++ starting up";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::ArcStartupRequest request;
  patchpanel::ArcStartupResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  if (!StartArc(request.pid()))
    LOG(ERROR) << "Failed to start ARC++ network service";

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnArcShutdown(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "ARC++ shutting down";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::ArcShutdownRequest request;
  patchpanel::ArcShutdownResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  StopArc();

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnArcVmStartup(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "ARCVM starting up";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::ArcVmStartupRequest request;
  patchpanel::ArcVmStartupResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  if (!StartArcVm(request.cid())) {
    LOG(ERROR) << "Failed to start ARCVM network service";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  // Populate the response with the known devices.
  for (const auto* config : arc_svc_->GetDeviceConfigs()) {
    if (config->tap_ifname().empty())
      continue;

    auto* dev = response.add_devices();
    dev->set_ifname(config->tap_ifname());
    dev->set_ipv4_addr(config->guest_ipv4_addr());
    dev->set_guest_type(NetworkDevice::ARCVM);
  }

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnArcVmShutdown(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "ARCVM shutting down";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::ArcVmShutdownRequest request;
  patchpanel::ArcVmShutdownResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  StopArcVm(request.cid());

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnTerminaVmStartup(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "Termina VM starting up";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::TerminaVmStartupRequest request;
  patchpanel::TerminaVmStartupResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  const int32_t cid = request.cid();
  if (!StartCrosVm(cid, GuestMessage::TERMINA_VM)) {
    LOG(ERROR) << "Failed to start Termina VM network service";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  const auto* const tap = cros_svc_->TAP(cid, true /*is_termina*/);
  if (!tap) {
    LOG(DFATAL) << "TAP device missing";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  auto* dev = response.mutable_device();
  dev->set_ifname(tap->host_ifname());
  dev->set_guest_type(NetworkDevice::TERMINA_VM);
  const auto* subnet = tap->config().ipv4_subnet();
  if (!subnet) {
    LOG(DFATAL) << "Missing required subnet for {cid: " << cid << "}";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }
  auto* resp_subnet = dev->mutable_ipv4_subnet();
  resp_subnet->set_base_addr(subnet->BaseAddress());
  resp_subnet->set_prefix_len(subnet->PrefixLength());
  subnet = tap->config().lxd_ipv4_subnet();
  if (!subnet) {
    LOG(DFATAL) << "Missing required lxd subnet for {cid: " << cid << "}";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }
  resp_subnet = response.mutable_container_subnet();
  resp_subnet->set_base_addr(subnet->BaseAddress());
  resp_subnet->set_prefix_len(subnet->PrefixLength());

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnTerminaVmShutdown(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "Termina VM shutting down";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::TerminaVmShutdownRequest request;
  patchpanel::TerminaVmShutdownResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  StopCrosVm(request.cid(), GuestMessage::TERMINA_VM);

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnPluginVmStartup(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "Plugin VM starting up";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::PluginVmStartupRequest request;
  patchpanel::PluginVmStartupResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  const uint64_t vm_id = request.id();
  if (!StartCrosVm(vm_id, GuestMessage::PLUGIN_VM, request.subnet_index())) {
    LOG(ERROR) << "Failed to start Plugin VM network service";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  const auto* const tap = cros_svc_->TAP(vm_id, false /*is_termina*/);
  if (!tap) {
    LOG(DFATAL) << "TAP device missing";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  auto* dev = response.mutable_device();
  dev->set_ifname(tap->host_ifname());
  dev->set_guest_type(NetworkDevice::PLUGIN_VM);
  const auto* subnet = tap->config().ipv4_subnet();
  if (!subnet) {
    LOG(DFATAL) << "Missing required subnet for {cid: " << vm_id << "}";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }
  auto* resp_subnet = dev->mutable_ipv4_subnet();
  resp_subnet->set_base_addr(subnet->BaseAddress());
  resp_subnet->set_prefix_len(subnet->PrefixLength());

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnPluginVmShutdown(
    dbus::MethodCall* method_call) {
  LOG(INFO) << "Plugin VM shutting down";

  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::PluginVmShutdownRequest request;
  patchpanel::PluginVmShutdownResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse request";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  StopCrosVm(request.id(), GuestMessage::PLUGIN_VM);

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnSetVpnIntent(
    dbus::MethodCall* method_call) {
  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::SetVpnIntentRequest request;
  patchpanel::SetVpnIntentResponse response;

  bool success = reader.PopArrayOfBytesAsProto(&request);
  if (!success) {
    LOG(ERROR) << "Unable to parse SetVpnIntentRequest";
    // Do not return yet to make sure we close the received fd.
  }

  base::ScopedFD client_socket;
  reader.PopFileDescriptor(&client_socket);

  if (success)
    success = routing_svc_->SetVpnFwmark(client_socket.get(), request.policy());

  response.set_success(success);

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnConnectNamespace(
    dbus::MethodCall* method_call) {
  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::ConnectNamespaceRequest request;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse ConnectNamespaceRequest";
    // Do not return yet to make sure we close the received fd and
    // validate other arguments.
    writer.AppendProtoAsArrayOfBytes(patchpanel::ConnectNamespaceResponse());
    return dbus_response;
  }

  base::ScopedFD client_fd;
  reader.PopFileDescriptor(&client_fd);
  if (!client_fd.is_valid()) {
    LOG(ERROR) << "ConnectNamespaceRequest: invalid file descriptor";
    writer.AppendProtoAsArrayOfBytes(patchpanel::ConnectNamespaceResponse());
    return dbus_response;
  }

  pid_t pid = request.pid();
  if (pid == 1 || pid == getpid()) {
    LOG(ERROR) << "ConnectNamespaceRequest: privileged namespace pid " << pid;
    writer.AppendProtoAsArrayOfBytes(patchpanel::ConnectNamespaceResponse());
    return dbus_response;
  }
  {
    ScopedNS ns(pid);
    if (!ns.IsValid()) {
      LOG(ERROR) << "ConnectNamespaceRequest: invalid namespace pid " << pid;
      writer.AppendProtoAsArrayOfBytes(patchpanel::ConnectNamespaceResponse());
      return dbus_response;
    }
  }

  const std::string& outbound_ifname = request.outbound_physical_device();
  if (!outbound_ifname.empty() && !shill_client_->has_device(outbound_ifname)) {
    LOG(ERROR) << "ConnectNamespaceRequest: invalid outbound ifname "
               << outbound_ifname;
    writer.AppendProtoAsArrayOfBytes(patchpanel::ConnectNamespaceResponse());
    return dbus_response;
  }

  auto response = ConnectNamespace(std::move(client_fd), request);
  writer.AppendProtoAsArrayOfBytes(*response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnGetTrafficCounters(
    dbus::MethodCall* method_call) {
  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::TrafficCountersRequest request;
  patchpanel::TrafficCountersResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse TrafficCountersRequest";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  const std::set<std::string> devices{request.devices().begin(),
                                      request.devices().end()};
  // TODO(b/175364240) Find why iptables -L -x -v -w can freeze on
  // writing to stdout and in turn block patchpanel.
  /*
  const auto counters = counters_svc_->GetCounters(devices);
  for (const auto& kv : counters) {
    auto* traffic_counter = response.add_counters();
    const auto& source_and_device = kv.first;
    const auto& counter = kv.second;
    traffic_counter->set_source(source_and_device.first);
    traffic_counter->set_device(source_and_device.second);
    traffic_counter->set_rx_bytes(counter.rx_bytes);
    traffic_counter->set_rx_packets(counter.rx_packets);
    traffic_counter->set_tx_bytes(counter.tx_bytes);
    traffic_counter->set_tx_packets(counter.tx_packets);
  }
  */

  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

std::unique_ptr<dbus::Response> Manager::OnModifyPortRule(
    dbus::MethodCall* method_call) {
  std::unique_ptr<dbus::Response> dbus_response(
      dbus::Response::FromMethodCall(method_call));

  dbus::MessageReader reader(method_call);
  dbus::MessageWriter writer(dbus_response.get());

  patchpanel::ModifyPortRuleRequest request;
  patchpanel::ModifyPortRuleResponse response;

  if (!reader.PopArrayOfBytesAsProto(&request)) {
    LOG(ERROR) << "Unable to parse ModifyPortRequest";
    writer.AppendProtoAsArrayOfBytes(response);
    return dbus_response;
  }

  response.set_success(ModifyPortRule(request));
  writer.AppendProtoAsArrayOfBytes(response);
  return dbus_response;
}

void Manager::OnNeighborReachabilityEvent(
    int ifindex,
    const shill::IPAddress& ip_addr,
    NeighborLinkMonitor::NeighborRole role,
    NeighborReachabilityEventSignal::EventType event_type) {
  if (!ip_addr.IsValid()) {
    LOG(DFATAL) << "ip_addr is not valid";
    return;
  }

  using SignalProto = NeighborReachabilityEventSignal;
  SignalProto proto;
  proto.set_ifindex(ifindex);
  proto.set_ip_addr(ip_addr.ToString());
  proto.set_type(event_type);
  switch (role) {
    case NeighborLinkMonitor::NeighborRole::kGateway:
      proto.set_role(SignalProto::GATEWAY);
      break;
    case NeighborLinkMonitor::NeighborRole::kDNSServer:
      proto.set_role(SignalProto::DNS_SERVER);
      break;
    case NeighborLinkMonitor::NeighborRole::kGatewayAndDNSServer:
      proto.set_role(SignalProto::GATEWAY_AND_DNS_SERVER);
      break;
    default:
      NOTREACHED();
  }

  dbus::Signal signal(kPatchPanelInterface, kNeighborReachabilityEventSignal);
  dbus::MessageWriter writer(&signal);
  if (!writer.AppendProtoAsArrayOfBytes(proto)) {
    LOG(ERROR) << "Failed to encode proto NeighborReachabilityEventSignal";
    return;
  }

  dbus_svc_path_->SendSignal(&signal);
}

std::unique_ptr<patchpanel::ConnectNamespaceResponse> Manager::ConnectNamespace(
    base::ScopedFD client_fd,
    const patchpanel::ConnectNamespaceRequest& request) {
  auto response = std::make_unique<patchpanel::ConnectNamespaceResponse>();

  std::unique_ptr<Subnet> subnet =
      addr_mgr_.AllocateIPv4Subnet(AddressManager::Guest::MINIJAIL_NETNS);
  if (!subnet) {
    LOG(ERROR) << "ConnectNamespace: exhausted IPv4 subnet space";
    return response;
  }

  // Dup the client fd into our own: this guarantees that the fd number will
  // be stable and tied to the actual kernel resources used by the client.
  base::ScopedFD local_client_fd(dup(client_fd.get()));
  if (!local_client_fd.is_valid()) {
    PLOG(ERROR) << "ConnectNamespace: failed to dup() client fd";
    return response;
  }

  // Add the duped fd to the epoll watcher.
  // TODO(hugobenichi) Find a way to reuse base::FileDescriptorWatcher for
  // listening to EPOLLHUP.
  struct epoll_event epevent;
  epevent.events = EPOLLIN;  // EPOLLERR | EPOLLHUP are always waited for.
  epevent.data.fd = local_client_fd.get();
  if (epoll_ctl(connected_namespaces_epollfd_, EPOLL_CTL_ADD,
                local_client_fd.get(), &epevent) != 0) {
    PLOG(ERROR) << "ConnectNamespace: epoll_ctl(EPOLL_CTL_ADD) failed";
    return response;
  }

  const std::string ifname_id = std::to_string(connected_namespaces_next_id_);
  ConnectedNamespace nsinfo = {};
  nsinfo.pid = request.pid();
  nsinfo.netns_name = "connected_netns_" + ifname_id;
  nsinfo.source = ProtoToTrafficSource(request.traffic_source());
  if (nsinfo.source == TrafficSource::UNKNOWN)
    nsinfo.source = TrafficSource::SYSTEM;
  nsinfo.outbound_ifname = request.outbound_physical_device();
  nsinfo.route_on_vpn = request.route_on_vpn();
  nsinfo.host_ifname = "arc_ns" + ifname_id;
  nsinfo.peer_ifname = "veth" + ifname_id;
  nsinfo.peer_subnet = std::move(subnet);
  nsinfo.peer_mac_addr = addr_mgr_.GenerateMacAddress();

  if (!datapath_->StartRoutingNamespace(nsinfo)) {
    LOG(ERROR) << "ConnectNamespace: failed to setup datapath";
    if (epoll_ctl(connected_namespaces_epollfd_, EPOLL_CTL_DEL,
                  local_client_fd.get(), nullptr) != 0)
      PLOG(ERROR) << "ConnectNamespace: epoll_ctl(EPOLL_CTL_DEL) failed";
    return response;
  }

  // Prepare the response before storing ConnectedNamespace.
  response->set_peer_ifname(nsinfo.peer_ifname);
  response->set_peer_ipv4_address(nsinfo.peer_subnet->AddressAtOffset(1));
  response->set_host_ifname(nsinfo.host_ifname);
  response->set_host_ipv4_address(nsinfo.peer_subnet->AddressAtOffset(0));
  auto* response_subnet = response->mutable_ipv4_subnet();
  response_subnet->set_base_addr(nsinfo.peer_subnet->BaseAddress());
  response_subnet->set_prefix_len(nsinfo.peer_subnet->PrefixLength());

  LOG(INFO) << "Connected network namespace " << nsinfo;

  // Store ConnectedNamespace
  connected_namespaces_next_id_++;
  int fdkey = local_client_fd.release();
  connected_namespaces_.insert(std::make_pair(fdkey, std::move(nsinfo)));

  if (connected_namespaces_.size() == 1) {
    LOG(INFO) << "Starting ConnectNamespace client fds monitoring";
    CheckConnectedNamespaces();
  }

  return response;
}

void Manager::DisconnectNamespace(int client_fd) {
  auto it = connected_namespaces_.find(client_fd);
  if (it == connected_namespaces_.end()) {
    LOG(ERROR) << "No ConnectedNamespace found for client_fd " << client_fd;
    return;
  }

  // Remove the client fd dupe from the epoll watcher and close it.
  if (epoll_ctl(connected_namespaces_epollfd_, EPOLL_CTL_DEL, client_fd,
                nullptr) != 0)
    PLOG(ERROR) << "DisconnectNamespace: epoll_ctl(EPOLL_CTL_DEL) failed";
  if (close(client_fd) < 0)
    PLOG(ERROR) << "DisconnectNamespace: close(client_fd) failed";

  datapath_->StopRoutingNamespace(it->second);
  LOG(INFO) << "Disconnected network namespace " << it->second;
  // This release the allocated IPv4 subnet.
  connected_namespaces_.erase(it);
}

// TODO(hugobenichi) Generalize this check to all resources created by
// patchpanel on behalf of a remote client.
void Manager::CheckConnectedNamespaces() {
  int max_event = 10;
  struct epoll_event epevents[max_event];
  int nready = epoll_wait(connected_namespaces_epollfd_, epevents, max_event,
                          0 /* do not block */);
  if (nready < 0)
    PLOG(ERROR) << "CheckConnectedNamespaces: epoll_wait(0) failed";

  for (int i = 0; i < nready; i++)
    if (epevents[i].events & (EPOLLHUP | EPOLLERR))
      DisconnectNamespace(epevents[i].data.fd);

  if (connected_namespaces_.empty()) {
    LOG(INFO) << "Stopping ConnectNamespace client fds monitoring";
    return;
  }

  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&Manager::CheckConnectedNamespaces,
                 weak_factory_.GetWeakPtr()),
      kConnectNamespaceCheckInterval);
}

bool Manager::ModifyPortRule(const patchpanel::ModifyPortRuleRequest& request) {
  switch (request.proto()) {
    case patchpanel::ModifyPortRuleRequest::TCP:
    case patchpanel::ModifyPortRuleRequest::UDP:
      break;
    default:
      LOG(ERROR) << "Unknown protocol " << request.proto();
      return false;
  }

  switch (request.op()) {
    case patchpanel::ModifyPortRuleRequest::CREATE:
      switch (request.type()) {
        case patchpanel::ModifyPortRuleRequest::ACCESS:
          return firewall_.AddAcceptRules(request.proto(),
                                          request.input_dst_port(),
                                          request.input_ifname());
        case patchpanel::ModifyPortRuleRequest::LOCKDOWN:
          return firewall_.AddLoopbackLockdownRules(request.proto(),
                                                    request.input_dst_port());
        case patchpanel::ModifyPortRuleRequest::FORWARDING:
          return firewall_.AddIpv4ForwardRule(
              request.proto(), request.input_dst_ip(), request.input_dst_port(),
              request.input_ifname(), request.dst_ip(), request.dst_port());
        default:
          LOG(ERROR) << "Unknown port rule type " << request.type();
          return false;
      }
    case patchpanel::ModifyPortRuleRequest::DELETE:
      switch (request.type()) {
        case patchpanel::ModifyPortRuleRequest::ACCESS:
          return firewall_.DeleteAcceptRules(request.proto(),
                                             request.input_dst_port(),
                                             request.input_ifname());
        case patchpanel::ModifyPortRuleRequest::LOCKDOWN:
          return firewall_.DeleteLoopbackLockdownRules(
              request.proto(), request.input_dst_port());
        case patchpanel::ModifyPortRuleRequest::FORWARDING:
          return firewall_.DeleteIpv4ForwardRule(
              request.proto(), request.input_dst_ip(), request.input_dst_port(),
              request.input_ifname(), request.dst_ip(), request.dst_port());
        default:
          LOG(ERROR) << "Unknown port rule type " << request.type();
          return false;
      }
    default:
      LOG(ERROR) << "Unknown operation " << request.op();
      return false;
  }
}

void Manager::SendGuestMessage(const GuestMessage& msg) {
  IpHelperMessage ipm;
  *ipm.mutable_guest_message() = msg;
  adb_proxy_->SendMessage(ipm);
  mcast_proxy_->SendMessage(ipm);
  nd_proxy_->SendMessage(ipm);
}

void Manager::StartForwarding(const std::string& ifname_physical,
                              const std::string& ifname_virtual,
                              bool ipv6,
                              bool multicast) {
  if (ifname_physical.empty() || ifname_virtual.empty())
    return;

  IpHelperMessage ipm;
  DeviceMessage* msg = ipm.mutable_device_message();
  msg->set_dev_ifname(ifname_physical);
  msg->set_br_ifname(ifname_virtual);

  if (ipv6) {
    LOG(INFO) << "Starting IPv6 forwarding from " << ifname_physical << " to "
              << ifname_virtual;

    if (!datapath_->AddIPv6Forwarding(ifname_physical, ifname_virtual)) {
      LOG(ERROR) << "Failed to setup iptables forwarding rule for IPv6 from "
                 << ifname_physical << " to " << ifname_virtual;
    }
    if (!datapath_->MaskInterfaceFlags(ifname_physical, IFF_ALLMULTI)) {
      LOG(WARNING) << "Failed to setup all multicast mode for interface "
                   << ifname_physical;
    }
    if (!datapath_->MaskInterfaceFlags(ifname_virtual, IFF_ALLMULTI)) {
      LOG(WARNING) << "Failed to setup all multicast mode for interface "
                   << ifname_virtual;
    }
    nd_proxy_->SendMessage(ipm);
  }

  if (multicast) {
    LOG(INFO) << "Starting multicast forwarding from " << ifname_physical
              << " to " << ifname_virtual;
    mcast_proxy_->SendMessage(ipm);
  }
}

void Manager::StopForwarding(const std::string& ifname_physical,
                             const std::string& ifname_virtual,
                             bool ipv6,
                             bool multicast) {
  if (ifname_physical.empty())
    return;

  IpHelperMessage ipm;
  DeviceMessage* msg = ipm.mutable_device_message();
  msg->set_dev_ifname(ifname_physical);
  msg->set_teardown(true);
  if (!ifname_virtual.empty()) {
    msg->set_br_ifname(ifname_virtual);
  }

  if (ipv6) {
    if (ifname_virtual.empty()) {
      LOG(INFO) << "Stopping IPv6 forwarding on " << ifname_physical;
    } else {
      LOG(INFO) << "Stopping IPv6 forwarding from " << ifname_physical << " to "
                << ifname_virtual;
      datapath_->RemoveIPv6Forwarding(ifname_physical, ifname_virtual);
    }
    nd_proxy_->SendMessage(ipm);
  }

  if (multicast) {
    if (ifname_virtual.empty()) {
      LOG(INFO) << "Stopping multicast forwarding on " << ifname_physical;
    } else {
      LOG(INFO) << "Stopping multicast forwarding from " << ifname_physical
                << " to " << ifname_virtual;
    }
    mcast_proxy_->SendMessage(ipm);
  }
}

void Manager::OnNDProxyMessage(const NDProxyMessage& msg) {
  LOG_IF(DFATAL, msg.ifname().empty())
      << "Received DeviceMessage w/ empty dev_ifname";
  switch (msg.type()) {
    case NDProxyMessage::ADD_ROUTE:
      if (!datapath_->AddIPv6HostRoute(msg.ifname(), msg.ip6addr(), 128)) {
        LOG(WARNING) << "Failed to setup the IPv6 route for interface "
                     << msg.ifname() << ", addr " << msg.ip6addr();
      }
      break;
    case NDProxyMessage::ADD_ADDR:
      if (!datapath_->AddIPv6Address(msg.ifname(), msg.ip6addr())) {
        LOG(WARNING) << "Failed to setup the IPv6 address for interface "
                     << msg.ifname() << ", addr " << msg.ip6addr();
      }
      break;
    case NDProxyMessage::DEL_ADDR:
      datapath_->RemoveIPv6Address(msg.ifname(), msg.ip6addr());
      break;
    default:
      LOG(ERROR) << "Unknown NDProxy event " << msg.type();
      NOTREACHED();
  }
}

}  // namespace patchpanel