Network

每获取一个网卡信息，都保存为一个Network对象实例。
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H:\webrtc-20210315\webrtc-20210315\webrtc\webrtc-checkout\src\rtc_base\network.h

  1.   Network(const std::string& name,
  2.           const std::string& description,
  3.           const IPAddress& prefix,
  4.           int prefix_length);
  6.   Network(const std::string& name,
  7.           const std::string& description,
  8.           const IPAddress& prefix,
  9.           int prefix_length,
  10.           AdapterType type);

代码分析

打断点
BasicNetworkManager::StartUpdating
BasicNetworkManager::CreateNetworks

BasicNetworkManager::StartUpdating

  1. void BasicNetworkManager::StartUpdating() {
  2.   thread_ = Thread::Current();
  3.   // Redundant but necessary for thread annotations.
  4.   RTC_DCHECK_RUN_ON(thread_);
  5.   if (start_count_) {
  6.     // If network interfaces are already discovered and signal is sent,
  7.     // we should trigger network signal immediately for the new clients
  8.     // to start allocating ports.
  9.     if (sent_first_update_)
  10.       thread_->Post(RTC_FROM_HERE, this, kSignalNetworksMessage);
  11.   } else {
  12.     thread_->Post(RTC_FROM_HERE, this, kUpdateNetworksMessage);
  13.     StartNetworkMonitor();
  14.   }
  15.   ++start_count_;
  16. }

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第一次发送的是kUpdateNetworksMessage信号

BasicNetworkManager::CreateNetworks

H:\webrtc-20210315\webrtc-20210315\webrtc\webrtc-checkout\src\rtc_base\network.cc

  1. bool BasicNetworkManager::CreateNetworks(bool include_ignored,
  2.                                          NetworkList* networks) const {
  3.   NetworkMap current_networks; //防止重复ip
  4.   // MSDN recommends a 15KB buffer for the first try at GetAdaptersAddresses.
  5.   size_t buffer_size = 16384;
  6.   std::unique_ptr<char[]> adapter_info(new char[buffer_size]);
  7.   PIP_ADAPTER_ADDRESSES adapter_addrs =
  8.       reinterpret_cast<PIP_ADAPTER_ADDRESSES>(adapter_info.get());
  9.   int adapter_flags = (GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_ANYCAST |
  10.                        GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_INCLUDE_PREFIX);
  11.   int ret = 0;
  12.   do { // 一般循环一次而已
  13.     adapter_info.reset(new char[buffer_size]);
  14.     adapter_addrs = reinterpret_cast<PIP_ADAPTER_ADDRESSES>(adapter_info.get());
  15.       // 同时获取ipv4和ipv6,
  16.     ret = GetAdaptersAddresses(AF_UNSPEC, adapter_flags, 0, adapter_addrs,
  17.                                reinterpret_cast<PULONG>(&buffer_size));
  18.   } while (ret == ERROR_BUFFER_OVERFLOW); // 防止内存不足，而使用while循环
  20.   if (ret != ERROR_SUCCESS) {
  21.     return false;
  22.   }
  23.   int count = 0;
  24.   while (adapter_addrs) {
  25.     if (adapter_addrs->OperStatus == IfOperStatusUp) {
  26.       PIP_ADAPTER_UNICAST_ADDRESS address = adapter_addrs->FirstUnicastAddress;
  27.       PIP_ADAPTER_PREFIX prefixlist = adapter_addrs->FirstPrefix;
  28.       std::string name;
  29.       std::string description;
  30. #if !defined(NDEBUG)
  31.       name = ToUtf8(adapter_addrs->FriendlyName,
  32.                     wcslen(adapter_addrs->FriendlyName));
  33. #endif
  34.       description = ToUtf8(adapter_addrs->Description,
  35.                            wcslen(adapter_addrs->Description));
  36.       for (; address; address = address->Next) {
  37. #if defined(NDEBUG)
  38.         name = rtc::ToString(count);
  39. #endif
  41.         IPAddress ip;
  42.         int scope_id = 0;
  43.         std::unique_ptr<Network> network;
  44.         switch (address->Address.lpSockaddr->sa_family) {
  45.           case AF_INET: {
  46.             sockaddr_in* v4_addr =
  47.                 reinterpret_cast<sockaddr_in*>(address->Address.lpSockaddr);
  48.             ip = IPAddress(v4_addr->sin_addr);
  49.             break;
  50.           }
  51.           case AF_INET6: {
  52.             sockaddr_in6* v6_addr =
  53.                 reinterpret_cast<sockaddr_in6*>(address->Address.lpSockaddr);
  54.             scope_id = v6_addr->sin6_scope_id;
  55.             ip = IPAddress(v6_addr->sin6_addr);
  57.             if (IsIgnoredIPv6(allow_mac_based_ipv6_, InterfaceAddress(ip))) {
  58.               continue;
  59.             }
  61.             break;
  62.           }
  63.           default: {
  64.             continue;
  65.           }
  66.         }
  68.         IPAddress prefix;
  69.         int prefix_length = GetPrefix(prefixlist, ip, &prefix);
  70.         std::string key = MakeNetworkKey(name, prefix, prefix_length);
  71.         auto existing_network = current_networks.find(key);
  72.         if (existing_network == current_networks.end()) {
  73.           AdapterType adapter_type = ADAPTER_TYPE_UNKNOWN;
  74.           switch (adapter_addrs->IfType) {
  75.             case IF_TYPE_SOFTWARE_LOOPBACK:
  76.               adapter_type = ADAPTER_TYPE_LOOPBACK;
  77.               break;
  78.             case IF_TYPE_ETHERNET_CSMACD:
  79.             case IF_TYPE_ETHERNET_3MBIT:
  80.             case IF_TYPE_IEEE80212:
  81.             case IF_TYPE_FASTETHER:
  82.             case IF_TYPE_FASTETHER_FX:
  83.             case IF_TYPE_GIGABITETHERNET: //以太网类型
  84.               adapter_type = ADAPTER_TYPE_ETHERNET;
  85.               break;
  86.             case IF_TYPE_IEEE80211: //wifi类型
  87.               adapter_type = ADAPTER_TYPE_WIFI;
  88.               break;
  89.             case IF_TYPE_WWANPP:
  90.             case IF_TYPE_WWANPP2: // 蜂窝类型，手机用的
  91.               adapter_type = ADAPTER_TYPE_CELLULAR;
  92.               break;
  93.             default:
  94.               // TODO(phoglund): Need to recognize other types as well.
  95.               adapter_type = ADAPTER_TYPE_UNKNOWN;
  96.               break;
  97.           }
  98.           std::unique_ptr<Network> network(new Network(
  99.               name, description, prefix, prefix_length, adapter_type));
  100.           network->set_default_local_address_provider(this);
  101.           network->set_mdns_responder_provider(this);
  102.           network->set_scope_id(scope_id);
  103.           network->AddIP(ip);
  104.           bool ignored = IsIgnoredNetwork(*network);
  105.           network->set_ignored(ignored);
  106.           if (include_ignored || !network->ignored()) {
  107.             current_networks[key] = network.get();
  108.             networks->push_back(network.release());
  109.           }
  110.         } else {
  111.           (*existing_network).second->AddIP(ip);
  112.         }
  113.       }
  114.       // Count is per-adapter - all 'Networks' created from the same
  115.       // adapter need to have the same name.
  116.       ++count;
  117.     }
  118.     adapter_addrs = adapter_addrs->Next;
  119.   }
  120.   return true;
  121. }

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这时候的是
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NetworkMap current_networks; //防止重复ip
获取到网卡信息后，下面使用while循环遍历。
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