// Copyright 2019 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/crostini_service.h"

#include <memory>
#include <utility>

#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 <chromeos/constants/vm_tools.h>
#include <chromeos/dbus/service_constants.h>
#include <dbus/message.h>
#include <dbus/object_path.h>

#include "patchpanel/adb_proxy.h"
#include "patchpanel/device.h"

namespace patchpanel {
namespace {
constexpr int32_t kInvalidID = 0;
constexpr int kDbusTimeoutMs = 200;
// The maximum number of ADB sideloading query failures before stopping.
constexpr int kAdbSideloadMaxTry = 5;
constexpr base::TimeDelta kAdbSideloadUpdateDelay =
    base::TimeDelta::FromMilliseconds(5000);

std::string MakeKey(uint64_t vm_id, bool is_termina) {
  return base::StringPrintf("%s:%s", is_termina ? "t" : "p",
                            base::NumberToString(vm_id).c_str());
}

bool ParseKey(const std::string& key, uint64_t* vm_id, bool* is_termina) {
  auto s =
      base::SplitString(key, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
  if (s.size() != 2 || !base::StringToUint64(s[1], vm_id) || s[0] != "t" ||
      s[0] != "p") {
    LOG(DFATAL) << "Invalid key: " + key;
    return false;
  }
  *is_termina = s[0] == "t";
  return true;
}

bool IsEthernetOrWifiDevice(const ShillClient::Device& device) {
  return device.type == ShillClient::Device::Type::kEthernet ||
         device.type == ShillClient::Device::Type::kWifi;
}

}  // namespace

CrostiniService::CrostiniService(
    ShillClient* shill_client,
    AddressManager* addr_mgr,
    Datapath* datapath,
    TrafficForwarder* forwarder,
    Device::ChangeEventHandler device_changed_handler)
    : shill_client_(shill_client),
      addr_mgr_(addr_mgr),
      datapath_(datapath),
      forwarder_(forwarder),
      device_changed_handler_(device_changed_handler),
      adb_sideloading_enabled_(false) {
  DCHECK(shill_client_);
  DCHECK(addr_mgr_);
  DCHECK(datapath_);
  DCHECK(forwarder_);

  dbus::Bus::Options options;
  options.bus_type = dbus::Bus::SYSTEM;

  bus_ = new dbus::Bus(options);
  if (!bus_->Connect()) {
    LOG(ERROR) << "Failed to connect to system bus";
  } else {
    CheckAdbSideloadingStatus();
  }

  shill_client_->RegisterDefaultDeviceChangedHandler(base::Bind(
      &CrostiniService::OnDefaultDeviceChanged, weak_factory_.GetWeakPtr()));
}

CrostiniService::~CrostiniService() {
  if (bus_)
    bus_->ShutdownAndBlock();
}

bool CrostiniService::Start(uint64_t vm_id, bool is_termina, int subnet_index) {
  if (vm_id == kInvalidID) {
    LOG(ERROR) << "Invalid VM id";
    return false;
  }

  const auto key = MakeKey(vm_id, is_termina);
  if (taps_.find(key) != taps_.end()) {
    LOG(WARNING) << "Already started for {id: " << vm_id << "}";
    return false;
  }

  auto tap = AddTAP(is_termina, subnet_index);
  if (!tap) {
    LOG(ERROR) << "Cannot start for {id: " << vm_id << "}";
    return false;
  }

  LOG(INFO) << "Crostini network service started for {id: " << vm_id << "}";
  StartForwarding(shill_client_->default_interface(), tap->host_ifname());
  auto source = is_termina ? TrafficSource::CROSVM : TrafficSource::PLUGINVM;
  datapath_->StartRoutingDevice("", tap->host_ifname(),
                                tap->config().host_ipv4_addr(), source,
                                true /*route_on_vpn*/);

  if (adb_sideloading_enabled_)
    StartAdbPortForwarding(tap->phys_ifname());

  device_changed_handler_.Run(
      *tap, Device::ChangeEvent::ADDED,
      is_termina ? GuestMessage::TERMINA_VM : GuestMessage::PLUGIN_VM);

  taps_.emplace(key, std::move(tap));
  return true;
}

void CrostiniService::Stop(uint64_t vm_id, bool is_termina) {
  const auto key = MakeKey(vm_id, is_termina);
  const auto it = taps_.find(key);
  if (it == taps_.end()) {
    LOG(WARNING) << "Unknown {id: " << vm_id << "}";
    return;
  }

  device_changed_handler_.Run(
      *it->second, Device::ChangeEvent::REMOVED,
      is_termina ? GuestMessage::TERMINA_VM : GuestMessage::PLUGIN_VM);

  const auto& ifname = it->second->host_ifname();
  auto source = is_termina ? TrafficSource::CROSVM : TrafficSource::PLUGINVM;
  datapath_->StopRoutingDevice("", ifname,
                               it->second->config().host_ipv4_addr(), source,
                               true /*route_on_vpn*/);
  StopForwarding(shill_client_->default_interface(), ifname);
  if (adb_sideloading_enabled_)
    StopAdbPortForwarding(ifname);
  datapath_->RemoveInterface(ifname);
  taps_.erase(key);

  LOG(INFO) << "Crostini network service stopped for {id: " << vm_id << "}";
}

const Device* const CrostiniService::TAP(uint64_t vm_id,
                                         bool is_termina) const {
  const auto it = taps_.find(MakeKey(vm_id, is_termina));
  if (it == taps_.end()) {
    return nullptr;
  }
  return it->second.get();
}

void CrostiniService::ScanDevices(
    base::RepeatingCallback<void(uint64_t, bool, const Device&)> callback)
    const {
  for (const auto& [key, dev] : taps_) {
    uint64_t vm_id;
    bool is_termina;
    if (ParseKey(key, &vm_id, &is_termina))
      callback.Run(vm_id, is_termina, *dev.get());
  }
}

std::unique_ptr<Device> CrostiniService::AddTAP(bool is_termina,
                                                int subnet_index) {
  auto ipv4_subnet = addr_mgr_->AllocateIPv4Subnet(
      is_termina ? AddressManager::Guest::VM_TERMINA
                 : AddressManager::Guest::VM_PLUGIN,
      subnet_index);
  if (!ipv4_subnet) {
    LOG(ERROR) << "Subnet already in use or unavailable.";
    return nullptr;
  }
  auto host_ipv4_addr = ipv4_subnet->AllocateAtOffset(0);
  if (!host_ipv4_addr) {
    LOG(ERROR) << "Host address already in use or unavailable.";
    return nullptr;
  }
  auto guest_ipv4_addr = ipv4_subnet->AllocateAtOffset(1);
  if (!guest_ipv4_addr) {
    LOG(ERROR) << "VM address already in use or unavailable.";
    return nullptr;
  }
  std::unique_ptr<Subnet> lxd_subnet;
  if (is_termina) {
    lxd_subnet =
        addr_mgr_->AllocateIPv4Subnet(AddressManager::Guest::CONTAINER);
    if (!lxd_subnet) {
      LOG(ERROR) << "lxd subnet already in use or unavailable.";
      return nullptr;
    }
  }

  const auto mac_addr = addr_mgr_->GenerateMacAddress(subnet_index);
  const std::string tap =
      datapath_->AddTAP("" /* auto-generate name */, &mac_addr,
                        host_ipv4_addr.get(), vm_tools::kCrosVmUser);
  if (tap.empty()) {
    LOG(ERROR) << "Failed to create TAP device.";
    return nullptr;
  }

  if (lxd_subnet) {
    // Setup lxd route for the container using the VM as a gateway.
    if (!datapath_->AddIPv4Route(ipv4_subnet->AddressAtOffset(1),
                                 lxd_subnet->AddressAtOffset(0),
                                 lxd_subnet->Netmask())) {
      LOG(ERROR) << "Failed to setup lxd route";
      return nullptr;
    }
  }

  auto config = std::make_unique<Device::Config>(
      mac_addr, std::move(ipv4_subnet), std::move(host_ipv4_addr),
      std::move(guest_ipv4_addr), std::move(lxd_subnet));

  Device::Options opts{
      .fwd_multicast = true,
      .ipv6_enabled = true,
  };

  return std::make_unique<Device>(tap, tap, "", std::move(config), opts);
}

void CrostiniService::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 (IsEthernetOrWifiDevice(prev_device)) {
    for (const auto& t : taps_)
      StopForwarding(prev_device.ifname, t.second->host_ifname());
  }

  if (IsEthernetOrWifiDevice(new_device)) {
    for (const auto& t : taps_)
      StartForwarding(new_device.ifname, t.second->host_ifname());
  }
}

void CrostiniService::StartForwarding(const std::string& phys_ifname,
                                      const std::string& virt_ifname) {
  if (!phys_ifname.empty())
    forwarder_->StartForwarding(phys_ifname, virt_ifname, true /*ipv6*/,
                                true /*multicast*/);
}

void CrostiniService::StopForwarding(const std::string& phys_ifname,
                                     const std::string& virt_ifname) {
  if (!phys_ifname.empty())
    forwarder_->StopForwarding(phys_ifname, virt_ifname, true /*ipv6*/,
                               true /*multicast*/);
}

void CrostiniService::StartAdbPortForwarding(const std::string& ifname) {
  if (!datapath_->AddAdbPortForwardRule(ifname)) {
    LOG(ERROR) << "Error adding ADB port forwarding rule for " << ifname;
    return;
  }

  if (!datapath_->AddAdbPortAccessRule(ifname)) {
    datapath_->DeleteAdbPortForwardRule(ifname);
    LOG(ERROR) << "Error adding ADB port access rule for " << ifname;
    return;
  }

  if (datapath_->runner().sysctl_w(
          "net.ipv4.conf." + ifname + ".route_localnet", "1") != 0) {
    LOG(ERROR) << "Failed to set up route localnet for " << ifname;
    return;
  }
}

void CrostiniService::StopAdbPortForwarding(const std::string& ifname) {
  datapath_->DeleteAdbPortForwardRule(ifname);
  datapath_->DeleteAdbPortAccessRule(ifname);
}

void CrostiniService::CheckAdbSideloadingStatus() {
  static int num_try = 0;
  if (num_try >= kAdbSideloadMaxTry) {
    LOG(WARNING) << "Failed to get ADB sideloading status after " << num_try
                 << " tries. ADB sideloading will not work";
    return;
  }

  dbus::ObjectProxy* proxy = bus_->GetObjectProxy(
      login_manager::kSessionManagerServiceName,
      dbus::ObjectPath(login_manager::kSessionManagerServicePath));
  dbus::MethodCall method_call(login_manager::kSessionManagerInterface,
                               login_manager::kSessionManagerQueryAdbSideload);
  std::unique_ptr<dbus::Response> dbus_response =
      proxy->CallMethodAndBlock(&method_call, kDbusTimeoutMs);

  if (!dbus_response) {
    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
        FROM_HERE,
        base::BindOnce(&CrostiniService::CheckAdbSideloadingStatus,
                       weak_factory_.GetWeakPtr()),
        kAdbSideloadUpdateDelay);
    num_try++;
    return;
  }

  dbus::MessageReader reader(dbus_response.get());
  reader.PopBool(&adb_sideloading_enabled_);
  if (!adb_sideloading_enabled_)
    return;

  // If ADB sideloading is enabled, start ADB forwarding on all configured
  // Crostini's TAP interfaces.
  for (const auto& tap : taps_) {
    StartAdbPortForwarding(tap.second->phys_ifname());
  }
}

}  // namespace patchpanel