connection_unittest.cc

// Copyright (c) 2012 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 <arpa/inet.h>
#include <linux/rtnetlink.h>

#include <string>
#include <vector>

#include <base/memory/scoped_ptr.h>
#include <gtest/gtest.h>
#include <gmock/gmock.h>

#include "shill/connection.h"
#include "shill/ipconfig.h"
#include "shill/mock_connection.h"
#include "shill/mock_control.h"
#include "shill/mock_device.h"
#include "shill/mock_device_info.h"
#include "shill/mock_resolver.h"
#include "shill/mock_routing_table.h"
#include "shill/mock_rtnl_handler.h"
#include "shill/routing_table_entry.h"

using std::string;
using std::vector;
using testing::_;
using testing::Mock;
using testing::NiceMock;
using testing::Return;
using testing::StrictMock;
using testing::Test;

namespace shill {

namespace {
const char kTestDeviceName0[] = "netdev0";
const int kTestDeviceInterfaceIndex0 = 123;
const char kTestDeviceName1[] = "netdev1";
const int kTestDeviceInterfaceIndex1 = 321;
const char kIPAddress0[] = "192.168.1.1";
const char kGatewayAddress0[] = "192.168.1.254";
const char kGatewayAddress1[] = "192.168.2.254";
const char kBroadcastAddress0[] = "192.168.1.255";
const char kNameServer0[] = "8.8.8.8";
const char kNameServer1[] = "8.8.9.9";
const int32 kPrefix0 = 24;
const int32 kPrefix1 = 31;
const char kSearchDomain0[] = "chromium.org";
const char kSearchDomain1[] = "google.com";
}  // namespace {}

class ConnectionTest : public Test {
 public:
  ConnectionTest()
      : device_info_(new StrictMock<MockDeviceInfo>(
            &control_,
            static_cast<EventDispatcher*>(NULL),
            static_cast<Metrics*>(NULL),
            static_cast<Manager*>(NULL))),
        connection_(new Connection(
            kTestDeviceInterfaceIndex0,
            kTestDeviceName0,
            Technology::kUnknown,
            device_info_.get())),
        ipconfig_(new IPConfig(&control_, kTestDeviceName0)),
        local_address_(IPAddress::kFamilyIPv4),
        broadcast_address_(IPAddress::kFamilyIPv4),
        gateway_address_(IPAddress::kFamilyIPv4),
        default_address_(IPAddress::kFamilyIPv4) {}

  virtual void SetUp() {
    ReplaceSingletons(connection_);
    properties_.address = kIPAddress0;
    properties_.subnet_prefix = kPrefix0;
    properties_.gateway = kGatewayAddress0;
    properties_.broadcast_address = kBroadcastAddress0;
    properties_.dns_servers.push_back(kNameServer0);
    properties_.dns_servers.push_back(kNameServer1);
    properties_.domain_search.push_back(kSearchDomain0);
    properties_.domain_search.push_back(kSearchDomain1);
    properties_.address_family = IPAddress::kFamilyIPv4;
    UpdateProperties();
    EXPECT_TRUE(local_address_.SetAddressFromString(kIPAddress0));
    EXPECT_TRUE(broadcast_address_.SetAddressFromString(kBroadcastAddress0));
    EXPECT_TRUE(gateway_address_.SetAddressFromString(kGatewayAddress0));
  }

  virtual void TearDown() {
    AddDestructorExpectations();
    connection_ = NULL;
  }

  void ReplaceSingletons(ConnectionRefPtr connection) {
    connection->resolver_ = &resolver_;
    connection->routing_table_ = &routing_table_;
    connection->rtnl_handler_ = &rtnl_handler_;
  }

  void UpdateProperties() {
    ipconfig_->UpdateProperties(properties_, true);
  }

  bool PinHostRoute(ConnectionRefPtr connection,
                    const IPConfig::Properties &properties) {
    return connection->PinHostRoute(properties);
  }

 protected:
  class DisconnectCallbackTarget {
   public:
    DisconnectCallbackTarget()
        : callback_(base::Bind(&DisconnectCallbackTarget::CallTarget,
                               base::Unretained(this))) {}

    MOCK_METHOD0(CallTarget, void());
    const base::Closure &callback() { return callback_; }

   private:
    base::Closure callback_;
  };

  void AddDestructorExpectations() {
    EXPECT_CALL(routing_table_, FlushRoutes(kTestDeviceInterfaceIndex0));
    EXPECT_CALL(routing_table_, FlushRoutesWithTag(kTestDeviceInterfaceIndex0));
    EXPECT_CALL(*device_info_.get(),
                FlushAddresses(kTestDeviceInterfaceIndex0));
  }

  // Returns a new test connection object. The caller usually needs to call
  // AddDestructorExpectations before destroying the object.
  ConnectionRefPtr GetNewConnection() {
    ConnectionRefPtr connection(new Connection(kTestDeviceInterfaceIndex0,
                                               kTestDeviceName0,
                                               Technology::kUnknown,
                                               device_info_.get()));
    ReplaceSingletons(connection);
    return connection;
  }

  scoped_ptr<StrictMock<MockDeviceInfo> > device_info_;
  ConnectionRefPtr connection_;
  MockControl control_;
  IPConfigRefPtr ipconfig_;
  IPConfig::Properties properties_;
  IPAddress local_address_;
  IPAddress broadcast_address_;
  IPAddress gateway_address_;
  IPAddress default_address_;
  StrictMock<MockResolver> resolver_;
  StrictMock<MockRoutingTable> routing_table_;
  StrictMock<MockRTNLHandler> rtnl_handler_;
};

namespace {

MATCHER_P2(IsIPAddress, address, prefix, "") {
  IPAddress match_address(address);
  match_address.set_prefix(prefix);
  return match_address.Equals(arg);
}

MATCHER(IsNonNullCallback, "") {
  return !arg.is_null();
}

}  // namespace

TEST_F(ConnectionTest, InitState) {
  EXPECT_EQ(kTestDeviceInterfaceIndex0, connection_->interface_index_);
  EXPECT_EQ(kTestDeviceName0, connection_->interface_name_);
  EXPECT_FALSE(connection_->is_default());
  EXPECT_FALSE(connection_->routing_request_count_);
}

TEST_F(ConnectionTest, AddConfig) {
  EXPECT_CALL(rtnl_handler_,
              AddInterfaceAddress(kTestDeviceInterfaceIndex0,
                                  IsIPAddress(local_address_, kPrefix0),
                                  IsIPAddress(broadcast_address_, 0),
                                  IsIPAddress(default_address_, 0)));
  EXPECT_CALL(routing_table_,
              SetDefaultRoute(kTestDeviceInterfaceIndex0,
                              IsIPAddress(gateway_address_, 0),
                              Connection::kNonDefaultMetricBase +
                              kTestDeviceInterfaceIndex0));
  EXPECT_CALL(routing_table_,
              ConfigureRoutes(kTestDeviceInterfaceIndex0,
                              ipconfig_,
                              Connection::kDefaultMetric));
  connection_->UpdateFromIPConfig(ipconfig_);

  EXPECT_CALL(routing_table_, SetDefaultMetric(kTestDeviceInterfaceIndex0,
                                               Connection::kDefaultMetric));
  EXPECT_CALL(resolver_, SetDNSFromLists(
      ipconfig_->properties().dns_servers,
      ipconfig_->properties().domain_search));

  scoped_refptr<MockDevice> device(new StrictMock<MockDevice>(
      &control_,
      reinterpret_cast<EventDispatcher *>(NULL),
      reinterpret_cast<Metrics *>(NULL),
      reinterpret_cast<Manager *>(NULL),
      kTestDeviceName0,
      string(),
      kTestDeviceInterfaceIndex0));
  EXPECT_CALL(*device_info_, GetDevice(kTestDeviceInterfaceIndex0))
      .WillOnce(Return(device));
  EXPECT_CALL(*device.get(), RequestPortalDetection())
      .WillOnce(Return(true));
  EXPECT_CALL(routing_table_, FlushCache())
      .WillOnce(Return(true));
  connection_->SetIsDefault(true);
  Mock::VerifyAndClearExpectations(&routing_table_);
  EXPECT_TRUE(connection_->is_default());

  EXPECT_CALL(routing_table_,
              SetDefaultMetric(kTestDeviceInterfaceIndex0,
                               Connection::kNonDefaultMetricBase +
                               kTestDeviceInterfaceIndex0));
  EXPECT_CALL(routing_table_, FlushCache())
      .WillOnce(Return(true));
  connection_->SetIsDefault(false);
  EXPECT_FALSE(connection_->is_default());
}

TEST_F(ConnectionTest, AddConfigWithPeer) {
  const string kPeerAddress("192.168.1.222");
  IPAddress peer_address(IPAddress::kFamilyIPv4);
  EXPECT_TRUE(peer_address.SetAddressFromString(kPeerAddress));
  properties_.peer_address = kPeerAddress;
  properties_.gateway = string();
  UpdateProperties();
  EXPECT_CALL(rtnl_handler_,
              AddInterfaceAddress(kTestDeviceInterfaceIndex0,
                                  IsIPAddress(local_address_, kPrefix0),
                                  IsIPAddress(broadcast_address_, 0),
                                  IsIPAddress(peer_address, 0)));
  EXPECT_CALL(routing_table_, SetDefaultRoute(_, _, _)).Times(0);
  EXPECT_CALL(routing_table_,
              ConfigureRoutes(kTestDeviceInterfaceIndex0,
                              ipconfig_,
                              Connection::kDefaultMetric));
  connection_->UpdateFromIPConfig(ipconfig_);
}

TEST_F(ConnectionTest, AddConfigWithBrokenNetmask) {
  // Assign a prefix that makes the gateway unreachable.
  properties_.subnet_prefix = kPrefix1;
  UpdateProperties();

  // Connection should override with a prefix which will allow the
  // gateway to be reachable.
  EXPECT_CALL(rtnl_handler_,
              AddInterfaceAddress(kTestDeviceInterfaceIndex0,
                                  IsIPAddress(local_address_, kPrefix0),
                                  IsIPAddress(broadcast_address_, 0),
                                  IsIPAddress(default_address_, 0)));
  EXPECT_CALL(routing_table_,
              SetDefaultRoute(kTestDeviceInterfaceIndex0,
                              IsIPAddress(gateway_address_, 0),
                              Connection::kNonDefaultMetricBase +
                              kTestDeviceInterfaceIndex0));
  EXPECT_CALL(routing_table_,
              ConfigureRoutes(kTestDeviceInterfaceIndex0,
                              ipconfig_,
                              Connection::kDefaultMetric));
  connection_->UpdateFromIPConfig(ipconfig_);

  // Assign a gateway address that violates the minimum plausible prefix
  // the Connection can assign.
  properties_.gateway = kGatewayAddress1;
  UpdateProperties();

  IPAddress gateway_address1(IPAddress::kFamilyIPv4);
  EXPECT_TRUE(gateway_address1.SetAddressFromString(kGatewayAddress1));
  // Connection cannot override this prefix, so it will switch to a
  // model where the peer address is set to the value of the gateway
  // address.
  EXPECT_CALL(rtnl_handler_,
              AddInterfaceAddress(kTestDeviceInterfaceIndex0,
                                  IsIPAddress(local_address_, kPrefix1),
                                  IsIPAddress(broadcast_address_, 0),
                                  IsIPAddress(gateway_address1, 0)));
  EXPECT_CALL(routing_table_,
              SetDefaultRoute(kTestDeviceInterfaceIndex0, _, _));
  EXPECT_CALL(routing_table_,
              ConfigureRoutes(kTestDeviceInterfaceIndex0, _, _));
  connection_->UpdateFromIPConfig(ipconfig_);
}

TEST_F(ConnectionTest, AddConfigReverse) {
  EXPECT_CALL(routing_table_, SetDefaultMetric(kTestDeviceInterfaceIndex0,
                                               Connection::kDefaultMetric));
  vector<string> empty_list;
  EXPECT_CALL(resolver_, SetDNSFromLists(empty_list, empty_list));
  scoped_refptr<MockDevice> device(new StrictMock<MockDevice>(
      &control_,
      reinterpret_cast<EventDispatcher *>(NULL),
      reinterpret_cast<Metrics *>(NULL),
      reinterpret_cast<Manager *>(NULL),
      kTestDeviceName0,
      string(),
      kTestDeviceInterfaceIndex0));
  EXPECT_CALL(*device_info_, GetDevice(kTestDeviceInterfaceIndex0))
      .WillOnce(Return(device));
  EXPECT_CALL(*device.get(), RequestPortalDetection())
      .WillOnce(Return(true));
  EXPECT_CALL(routing_table_, FlushCache())
      .WillOnce(Return(true));
  connection_->SetIsDefault(true);
  Mock::VerifyAndClearExpectations(&routing_table_);

  EXPECT_CALL(rtnl_handler_,
              AddInterfaceAddress(kTestDeviceInterfaceIndex0,
                                  IsIPAddress(local_address_, kPrefix0),
                                  IsIPAddress(broadcast_address_, 0),
                                  IsIPAddress(default_address_, 0)));
  EXPECT_CALL(routing_table_, SetDefaultRoute(kTestDeviceInterfaceIndex0,
                                              IsIPAddress(gateway_address_, 0),
                                              Connection::kDefaultMetric));
  EXPECT_CALL(routing_table_,
              ConfigureRoutes(kTestDeviceInterfaceIndex0,
                              ipconfig_,
                              Connection::kDefaultMetric));
  EXPECT_CALL(resolver_, SetDNSFromIPConfig(ipconfig_));

  connection_->UpdateFromIPConfig(ipconfig_);
}

TEST_F(ConnectionTest, RouteRequest) {
  ConnectionRefPtr connection = GetNewConnection();
  scoped_refptr<MockDevice> device(new StrictMock<MockDevice>(
      &control_,
      reinterpret_cast<EventDispatcher *>(NULL),
      reinterpret_cast<Metrics *>(NULL),
      reinterpret_cast<Manager *>(NULL),
      kTestDeviceName0,
      string(),
      kTestDeviceInterfaceIndex0));
  EXPECT_CALL(*device_info_, GetDevice(kTestDeviceInterfaceIndex0))
      .WillRepeatedly(Return(device));
  EXPECT_CALL(*device.get(), DisableReversePathFilter()).Times(1);
  connection->RequestRouting();
  connection->RequestRouting();

  // The first release should only decrement the reference counter.
  connection->ReleaseRouting();

  // Another release will re-enable reverse-path filter.
  EXPECT_CALL(*device.get(), EnableReversePathFilter());
  EXPECT_CALL(routing_table_, FlushCache());
  connection->ReleaseRouting();

  // The destructor will remove the routes and addresses.
  AddDestructorExpectations();
}

TEST_F(ConnectionTest, Destructor) {
  ConnectionRefPtr connection(new Connection(kTestDeviceInterfaceIndex1,
                                             kTestDeviceName1,
                                             Technology::kUnknown,
                                             device_info_.get()));
  connection->resolver_ = &resolver_;
  connection->routing_table_ = &routing_table_;
  connection->rtnl_handler_ = &rtnl_handler_;
  EXPECT_CALL(routing_table_, FlushRoutes(kTestDeviceInterfaceIndex1));
  EXPECT_CALL(routing_table_, FlushRoutesWithTag(kTestDeviceInterfaceIndex1));
  EXPECT_CALL(*device_info_, FlushAddresses(kTestDeviceInterfaceIndex1));
  connection = NULL;
}

TEST_F(ConnectionTest, RequestHostRoute) {
  ConnectionRefPtr connection = GetNewConnection();
  IPAddress address(IPAddress::kFamilyIPv4);
  ASSERT_TRUE(address.SetAddressFromString(kIPAddress0));
  size_t prefix_len = address.GetLength() * 8;
  EXPECT_CALL(routing_table_,
              RequestRouteToHost(IsIPAddress(address, prefix_len),
                                 -1,
                                 kTestDeviceInterfaceIndex0,
                                 IsNonNullCallback()))
      .WillOnce(Return(true));
  EXPECT_TRUE(connection->RequestHostRoute(address));

  // The destructor will remove the routes and addresses.
  AddDestructorExpectations();
}

TEST_F(ConnectionTest, PinHostRoute) {
  static const char kGateway[] = "10.242.2.13";
  static const char kNetwork[] = "10.242.2.1";

  ConnectionRefPtr connection = GetNewConnection();

  IPConfig::Properties props;
  props.address_family = IPAddress::kFamilyIPv4;
  EXPECT_FALSE(PinHostRoute(connection, props));

  props.gateway = kGateway;
  EXPECT_FALSE(PinHostRoute(connection, props));

  props.gateway.clear();
  props.trusted_ip = "xxx";
  EXPECT_FALSE(PinHostRoute(connection, props));

  props.gateway = kGateway;
  EXPECT_FALSE(PinHostRoute(connection, props));

  props.trusted_ip = kNetwork;
  IPAddress address(IPAddress::kFamilyIPv4);
  ASSERT_TRUE(address.SetAddressFromString(kNetwork));
  size_t prefix_len = address.GetLength() * 8;
  EXPECT_CALL(routing_table_, RequestRouteToHost(
      IsIPAddress(address, prefix_len), -1, kTestDeviceInterfaceIndex0, _))
      .WillOnce(Return(false));
  EXPECT_FALSE(PinHostRoute(connection, props));

  EXPECT_CALL(routing_table_, RequestRouteToHost(
      IsIPAddress(address, prefix_len), -1, kTestDeviceInterfaceIndex0, _))
      .WillOnce(Return(true));
  EXPECT_TRUE(PinHostRoute(connection, props));

  // The destructor will remove the routes and addresses.
  AddDestructorExpectations();
}

TEST_F(ConnectionTest, FixGatewayReachability) {
  static const char kLocal[] = "10.242.2.13";
  IPAddress local(IPAddress::kFamilyIPv4);
  ASSERT_TRUE(local.SetAddressFromString(kLocal));
  const int kPrefix = 24;
  local.set_prefix(kPrefix);
  IPAddress gateway(IPAddress::kFamilyIPv4);
  IPAddress peer(IPAddress::kFamilyIPv4);

  // Should fail because no gateway is set.
  EXPECT_FALSE(Connection::FixGatewayReachability(&local, &peer, gateway));
  EXPECT_EQ(kPrefix, local.prefix());
  EXPECT_FALSE(peer.IsValid());

  // Should succeed because with the given prefix, this gateway is reachable.
  static const char kReachableGateway[] = "10.242.2.14";
  ASSERT_TRUE(gateway.SetAddressFromString(kReachableGateway));
  peer = IPAddress(IPAddress::kFamilyIPv4);
  EXPECT_TRUE(Connection::FixGatewayReachability(&local, &peer, gateway));
  // Prefix should remain unchanged.
  EXPECT_EQ(kPrefix, local.prefix());
  // Peer should remain unchanged.
  EXPECT_FALSE(peer.IsValid());

  // Should succeed because we modified the prefix to match the gateway.
  static const char kExpandableGateway[] = "10.242.3.14";
  ASSERT_TRUE(gateway.SetAddressFromString(kExpandableGateway));
  peer = IPAddress(IPAddress::kFamilyIPv4);
  EXPECT_TRUE(Connection::FixGatewayReachability(&local, &peer, gateway));
  // Prefix should have opened up by 1 bit.
  EXPECT_EQ(kPrefix - 1, local.prefix());
  // Peer should remain unchanged.
  EXPECT_FALSE(peer.IsValid());

  // Should change models to assuming point-to-point because we cannot
  // plausibly expand the prefix past 8.
  local.set_prefix(kPrefix);
  static const char kUnreachableGateway[] = "11.242.2.14";
  ASSERT_TRUE(gateway.SetAddressFromString(kUnreachableGateway));
  peer = IPAddress(IPAddress::kFamilyIPv4);
  EXPECT_TRUE(Connection::FixGatewayReachability(&local, &peer, gateway));
  // Prefix should not have changed.
  EXPECT_EQ(kPrefix, local.prefix());
  // Peer address should be set to the gateway address.
  EXPECT_TRUE(peer.Equals(gateway));

  // Should also use point-to-point model if the netmask is set to the
  // "all-ones" addresss, even if this address could have been made
  // accessible by plausibly changing the prefix.
  const int kIPv4MaxPrefix =
      IPAddress::GetMaxPrefixLength(IPAddress::kFamilyIPv4);
  local.set_prefix(kIPv4MaxPrefix);
  ASSERT_TRUE(gateway.SetAddressFromString(kExpandableGateway));
  peer = IPAddress(IPAddress::kFamilyIPv4);
  EXPECT_TRUE(Connection::FixGatewayReachability(&local, &peer, gateway));
  // Prefix should not have changed.
  EXPECT_EQ(kIPv4MaxPrefix, local.prefix());
  // Peer address should be set to the gateway address.
  EXPECT_TRUE(peer.Equals(gateway));

  // If this is a peer-to-peer interface and the peer matches the gateway,
  // we should succeed.
  local.set_prefix(kPrefix);
  ASSERT_TRUE(gateway.SetAddressFromString(kUnreachableGateway));
  ASSERT_TRUE(peer.SetAddressFromString(kUnreachableGateway));
  EXPECT_TRUE(Connection::FixGatewayReachability(&local, &peer, gateway));
  EXPECT_EQ(kPrefix, local.prefix());
  EXPECT_TRUE(peer.Equals(gateway));

  // If there is a peer specified and it does not match the gateway (even
  // if it was reachable via netmask), we should fail.
  ASSERT_TRUE(gateway.SetAddressFromString(kReachableGateway));
  EXPECT_FALSE(Connection::FixGatewayReachability(&local, &peer, gateway));
  EXPECT_EQ(kPrefix, local.prefix());
  EXPECT_FALSE(peer.Equals(gateway));
}

TEST_F(ConnectionTest, Binders) {
  EXPECT_TRUE(connection_->binders_.empty());
  DisconnectCallbackTarget target0;
  DisconnectCallbackTarget target1;
  DisconnectCallbackTarget target2;
  DisconnectCallbackTarget target3;
  Connection::Binder binder0("binder0", target0.callback());
  Connection::Binder binder1("binder1", target1.callback());
  Connection::Binder binder2("binder2", target2.callback());
  Connection::Binder binder3("binder3", target3.callback());

  binder0.Attach(connection_);
  binder1.Attach(connection_);

  EXPECT_CALL(target1, CallTarget()).Times(0);
  binder1.Attach(connection_);

  binder3.Attach(connection_);
  binder2.Attach(connection_);

  EXPECT_CALL(target3, CallTarget()).Times(0);
  binder3.Attach(NULL);

  ASSERT_EQ(3, connection_->binders_.size());
  EXPECT_TRUE(connection_->binders_.at(0) == &binder0);
  EXPECT_TRUE(connection_->binders_.at(1) == &binder1);
  EXPECT_TRUE(connection_->binders_.at(2) == &binder2);

  EXPECT_CALL(target0, CallTarget()).Times(1);
  EXPECT_CALL(target1, CallTarget()).Times(1);
  EXPECT_CALL(target2, CallTarget()).Times(1);
  connection_->NotifyBindersOnDisconnect();
  EXPECT_TRUE(connection_->binders_.empty());

  // Should be a no-op.
  connection_->NotifyBindersOnDisconnect();
}

TEST_F(ConnectionTest, Binder) {
  // No connection should be bound initially.
  Connection::Binder *binder = &connection_->lower_binder_;
  EXPECT_EQ(connection_->interface_name(), binder->name_);
  EXPECT_FALSE(binder->client_disconnect_callback_.is_null());
  EXPECT_FALSE(binder->IsBound());

  ConnectionRefPtr connection1 = GetNewConnection();
  EXPECT_TRUE(connection1->binders_.empty());

  // Bind lower |connection1| and check if it's bound.
  binder->Attach(connection1);
  EXPECT_TRUE(binder->IsBound());
  EXPECT_EQ(connection1.get(), binder->connection().get());
  ASSERT_FALSE(connection1->binders_.empty());
  EXPECT_TRUE(binder == connection1->binders_.at(0));

  // Unbind lower |connection1| and check if it's unbound.
  binder->Attach(NULL);
  EXPECT_FALSE(binder->IsBound());
  EXPECT_TRUE(connection1->binders_.empty());

  ConnectionRefPtr connection2 = GetNewConnection();

  // Bind lower |connection1| to upper |connection2| and destroy the upper
  // |connection2|. Make sure lower |connection1| is unbound (i.e., the
  // disconnect callback is deregistered).
  connection2->lower_binder_.Attach(connection1);
  EXPECT_FALSE(connection1->binders_.empty());
  AddDestructorExpectations();
  connection2 = NULL;
  EXPECT_TRUE(connection1->binders_.empty());

  // Bind lower |connection1| to upper |connection_| and destroy lower
  // |connection1|. Make sure lower |connection1| is unbound from upper
  // |connection_| and upper |connection_|'s registered disconnect callbacks are
  // run.
  binder->Attach(connection1);
  DisconnectCallbackTarget target;
  Connection::Binder test_binder("from_test", target.callback());
  test_binder.Attach(connection_);
  EXPECT_CALL(target, CallTarget()).Times(1);
  ASSERT_FALSE(connection_->binders_.empty());
  AddDestructorExpectations();
  connection1 = NULL;
  EXPECT_FALSE(binder->IsBound());
  EXPECT_FALSE(test_binder.IsBound());
  EXPECT_TRUE(connection_->binders_.empty());

  {
    // Binding a connection to itself should be safe.
    ConnectionRefPtr connection = GetNewConnection();

    connection->lower_binder_.Attach(connection);

    EXPECT_FALSE(connection->binders_.empty());

    DisconnectCallbackTarget target;
    Connection::Binder binder("test", target.callback());
    binder.Attach(connection);

    AddDestructorExpectations();
    EXPECT_CALL(target, CallTarget()).Times(1);
    connection = NULL;
  }
  {
    // Circular binding of multiple connections should be safe.
    ConnectionRefPtr connection_a = GetNewConnection();
    ConnectionRefPtr connection_b = GetNewConnection();

    connection_a->lower_binder_.Attach(connection_b);
    connection_b->lower_binder_.Attach(connection_a);

    EXPECT_FALSE(connection_a->binders_.empty());
    EXPECT_FALSE(connection_b->binders_.empty());

    DisconnectCallbackTarget target_a;
    DisconnectCallbackTarget target_b;
    Connection::Binder binder_a("test_a", target_a.callback());
    Connection::Binder binder_b("test_b", target_b.callback());
    binder_a.Attach(connection_a);
    binder_b.Attach(connection_b);

    AddDestructorExpectations();
    EXPECT_CALL(target_a, CallTarget()).Times(1);
    EXPECT_CALL(target_b, CallTarget()).Times(1);
    connection_b = NULL;

    EXPECT_TRUE(connection_a->binders_.empty());

    AddDestructorExpectations();
    connection_a = NULL;
  }
  {
    // Test the weak pointer to the bound Connection. This is not a case that
    // should occur but the weak pointer should handle it gracefully.
    DisconnectCallbackTarget target;
    Connection::Binder binder("test_weak", target.callback());
    ConnectionRefPtr connection = GetNewConnection();
    binder.Attach(connection);

    // Make sure the connection doesn't notify the binder on destruction.
    connection->binders_.clear();
    AddDestructorExpectations();
    EXPECT_CALL(target, CallTarget()).Times(0);
    connection = NULL;

    // Ensure no crash -- the weak pointer to connection should be NULL.
    EXPECT_FALSE(binder.connection());
    binder.Attach(NULL);
  }
}

TEST_F(ConnectionTest, OnRouteQueryResponse) {
  Connection::Binder *binder = &connection_->lower_binder_;
  ConnectionRefPtr connection = GetNewConnection();
  scoped_refptr<MockDevice> device(new StrictMock<MockDevice>(
      &control_,
      reinterpret_cast<EventDispatcher *>(NULL),
      reinterpret_cast<Metrics *>(NULL),
      reinterpret_cast<Manager *>(NULL),
      kTestDeviceName1,
      string(),
      kTestDeviceInterfaceIndex1));

  // Make sure we unbind the old lower connection even if we can't lookup the
  // lower connection device.
  binder->Attach(connection);
  scoped_refptr<MockDevice> null_device;
  EXPECT_CALL(*device_info_, GetDevice(kTestDeviceInterfaceIndex1))
      .WillOnce(Return(null_device));
  connection_->OnRouteQueryResponse(
      kTestDeviceInterfaceIndex1, RoutingTableEntry());
  EXPECT_FALSE(binder->IsBound());

  // Check for graceful handling of a device with no connection.
  EXPECT_CALL(*device_info_, GetDevice(kTestDeviceInterfaceIndex1))
      .WillOnce(Return(device));
  connection_->OnRouteQueryResponse(
      kTestDeviceInterfaceIndex1, RoutingTableEntry());
  EXPECT_FALSE(binder->IsBound());

  // Check that the upper connection is bound to the lower connection.
  device->connection_ = connection;
  EXPECT_CALL(*device_info_, GetDevice(kTestDeviceInterfaceIndex1))
      .WillOnce(Return(device));
  connection_->OnRouteQueryResponse(
      kTestDeviceInterfaceIndex1, RoutingTableEntry());
  EXPECT_TRUE(binder->IsBound());
  EXPECT_EQ(connection.get(), binder->connection().get());

  device->connection_ = NULL;
  AddDestructorExpectations();
  connection = NULL;
}

}  // namespace shill