Add DiscoveryNetworkMonitor implementation

chrome/browser/net/discovery_network_monitor.cc

+// Copyright (c) 2017 The Chromium 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 "chrome/browser/net/discovery_network_monitor.h"
+
+#include <iostream>
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "chrome/browser/net/discovery_network_list.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/network_interfaces.h"
+
+namespace {
+
+using content::BrowserThread;
+
+std::vector<NetworkInfo> GetNetworkInfo() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  net::NetworkInterfaceList interface_list;
+  if (!net::GetNetworkList(&interface_list,
+                           net::INCLUDE_HOST_SCOPE_VIRTUAL_INTERFACES)) {
+    DVLOG(2) << "net::GetNetworkList failed after a network change event";
+    return std::vector<NetworkInfo>();
+  }
+
+  std::vector<NetworkInfo> network_info_list;
+  for (const auto& interface : interface_list) {
+    if (interface.type != net::NetworkChangeNotifier::CONNECTION_ETHERNET &&
+        interface.type != net::NetworkChangeNotifier::CONNECTION_WIFI) {
+      continue;
+    }
+    network_info_list.push_back(
+        NetworkInfo{interface.interface_index, interface.type, interface.name,
+                    std::string(""), interface.address});
+  }
+
+  auto network_ids = GetDiscoveryNetworkIdList();
+  for (const auto& network_id : network_ids) {
+    auto matching_info_it =
+        std::find_if(begin(network_info_list), end(network_info_list),
+                     [&network_id](const NetworkInfo& network_info) {
+                       return network_info.name == network_id.interface_name;
+                     });
+    if (matching_info_it != end(network_info_list)) {
+      matching_info_it->network_id = network_id.network_id;

[imcheng, 2017/03/14 22:45:35]

So it looks like we are combining information from two lists. Can we actually
figure out the "network_id" using only information from |interface_list|?

If it's Ethernet, then you can figure out the MAC address with SIOCGIFHWADDR:
http://www.microhowto.info/howto/get_the_mac_address_of_an_ethernet_interface...

Otherwise it is WiFi, it seems like you want to get its SSID.

[btolsch, 2017/04/03 10:16:35]

Although this is possible on linux, as best as I can tell for mac and windows so
far, you can't get the MAC address for a single interface by itself; you have to
get a list of interface info for the whole system and then search the list.

+    }
+  }
+  return network_info_list;

[imcheng, 2017/03/14 22:45:35]

Do we know if the networks in the returned list are all connected?

[btolsch, 2017/04/03 10:16:35]

Yes, it looks like net::GetNetworkList only returns interfaces that are
connected.

+}
+
+base::LazyInstance<DiscoveryNetworkMonitor>::Leaky g_discovery_monitor;
+
+}  // namespace
+NetworkInfo::NetworkInfo() {}
+
+NetworkInfo::NetworkInfo(
+    uint32_t index,
+    net::NetworkChangeNotifier::ConnectionType connection_type,
+    std::string name,
+    std::string network_id,
+    net::IPAddress ip_address)
+    : index(index),
+      connection_type(connection_type),
+      name(name),
+      network_id(network_id),
+      ip_address(ip_address) {}
+
+NetworkInfo::NetworkInfo(const NetworkInfo&) = default;
+
+NetworkInfo& NetworkInfo::operator=(const NetworkInfo&) = default;
+
+DiscoveryNetworkMonitor::DiscoveryNetworkMonitor()
+    : observers_(new base::ObserverListThreadSafe<Observer>(
+          base::ObserverListThreadSafe<
+              Observer>::NotificationType::NOTIFY_EXISTING_ONLY)) {
+  net::NetworkChangeNotifier::AddNetworkChangeObserver(this);
+}
+
+DiscoveryNetworkMonitor::~DiscoveryNetworkMonitor() {
+  net::NetworkChangeNotifier::RemoveNetworkChangeObserver(this);
+}
+
+DiscoveryNetworkMonitor* DiscoveryNetworkMonitor::GetInstance() {
+  DiscoveryNetworkMonitor* monitor = g_discovery_monitor.Pointer();
+  if (!monitor->network_info_strategy_) {
+    monitor->network_info_strategy_ = base::Bind(&GetNetworkInfo);
+  }
+  return monitor;
+}
+
+DiscoveryNetworkMonitor* DiscoveryNetworkMonitor::GetInstanceForTest(
+    NetworkInfoStrategy strategy) {
+  DiscoveryNetworkMonitor* monitor = g_discovery_monitor.Pointer();
+  monitor->network_info_strategy_ = std::move(strategy);
+  return monitor;
+}
+
+void DiscoveryNetworkMonitor::RebindNetworkChangeObserverForTest() {
+  net::NetworkChangeNotifier::AddNetworkChangeObserver(this);
+}
+
+void DiscoveryNetworkMonitor::AddObserver(Observer* const observer) {
+  observers_->AddObserver(observer);
+}
+
+void DiscoveryNetworkMonitor::RemoveObserver(Observer* const observer) {
+  observers_->RemoveObserver(observer);
+}
+
+void DiscoveryNetworkMonitor::ForceNetworkInfoRefresh(
+    NetworkRefreshCompleteCallback callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&DiscoveryNetworkMonitor::UpdateNetworkInfoWithCallback,
+                 base::Unretained(this), callback));
+}
+
+void DiscoveryNetworkMonitor::OnNetworkChanged(
+    net::NetworkChangeNotifier::ConnectionType) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&DiscoveryNetworkMonitor::UpdateNetworkInfoWithObservers,
+                 base::Unretained(this)));
+}
+
+std::string DiscoveryNetworkMonitor::ComputeNetworkId(
+    const std::vector<NetworkInfo>& network_info_list) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (network_info_list.size() == 0) {
+    return std::string("disconnected");

[mark a. foltz, 2017/03/18 19:58:21]

Can these special network id constants be defined at the file level?

[btolsch, 2017/04/03 10:16:36]

Done.

+  }
+  std::string network_ids;
+  for (const auto& network_info : network_info_list) {
+    network_ids += network_info.network_id;
+  }
+  if (network_ids.size() == 0) {
+    return std::string("unknown");
+  }
+  int folded_ids = 0;
+  unsigned long size = network_ids.size();
+  for (unsigned long i = 0; i < size; ++i) {
+    folded_ids ^= network_ids[i] << (8 * (i % 2));

[mark a. foltz, 2017/03/18 19:58:21]

What is this computing?  Maybe you can just compute a SHA-1 of the string.  It
doesn't have to be secure, just rare to have collisions.

[btolsch, 2017/04/03 10:16:35]

Done.

+  }
+
+  std::string network_id = "#_____";
+  network_id[5] = '0' + (folded_ids % 10);
+  folded_ids /= 10;
+  network_id[4] = '0' + (folded_ids % 10);
+  folded_ids /= 10;
+  network_id[3] = '0' + (folded_ids % 10);
+  folded_ids /= 10;
+  network_id[2] = '0' + (folded_ids % 10);
+  folded_ids /= 10;
+  network_id[1] = '0' + (folded_ids % 10);
+
+  return network_id;

[imcheng, 2017/03/14 22:45:35]

Is the purpose of this to mimic the Cast MRP logic to determine the "combined"
network ID?

Does the order of the networks in network_info_list matter? 

[btolsch, 2017/04/03 10:16:35]

The order shouldn't matter.  I added a sort to the IDs before the hash.

+}
+
+void DiscoveryNetworkMonitor::UpdateNetworkInfo() {

[mark a. foltz, 2017/03/18 19:58:21]

Will this get called when WiFi SSIDs change?

[btolsch, 2017/04/03 10:16:35]

I guess that depends on whether NetworkChangeNotifier sees the
connect/disconnect.  Is it possible to change a network's SSID without the
clients disconnecting?

+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  auto network_info_list = network_info_strategy_.Run();
+  auto network_id = ComputeNetworkId(network_info_list);
+
+  base::AutoLock auto_lock(network_info_lock_);
+  networks_.swap(network_info_list);
+  network_id_.swap(network_id);
+}
+
+void DiscoveryNetworkMonitor::UpdateNetworkInfoWithObservers() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  UpdateNetworkInfo();
+
+  observers_->Notify(FROM_HERE, &Observer::OnNetworksChanged,

[mark a. foltz, 2017/03/18 19:58:21]

Do you only want to do this if the network list / id had changed?

[btolsch, 2017/04/03 10:16:35]

Yes. Done.

+                     base::ConstRef(*this));
+}
+
+void DiscoveryNetworkMonitor::UpdateNetworkInfoWithCallback(

[mark a. foltz, 2017/03/18 19:58:21]

Maybe UpdateNetworkInfo() could always update observers if the underlying id has
changed, and take an optional callback to always invoke with the current id?

[btolsch, 2017/04/03 10:16:35]

Done.

+    NetworkRefreshCompleteCallback callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  UpdateNetworkInfo();
+
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, callback);
+}