ifaddr.cc

#include <iostream>
#include <unordered_map>

extern "C" {
#include <arpa/inet.h>
#include <sys/socket.h>
#include <ifaddrs.h>
}

std::unordered_map<std::string, std::string> get_if_list() {
  std::unordered_map<std::string, std::string> result;

  ifaddrs* ifap;
  getifaddrs(&ifap);

  for (auto ifa = ifap; ifa; ifa = ifa->ifa_next) {
    if (ifa->ifa_addr->sa_family == AF_INET) {
      auto sa = reinterpret_cast<sockaddr_in*>(ifa->ifa_addr);
      result.insert({ifa->ifa_name, inet_ntoa(sa->sin_addr)});
    }
  }

  freeifaddrs(ifap);

  return result;
}

auto main() -> int {
  const auto ifs = get_if_list();

  for (auto&& i : ifs) {
    std::cout << i.first << "\t" << i.second << std::endl;
  }
}

ifaddr_win.cc

#include <cstdlib>
#include <iostream>

extern "C" {
#include <winsock2.h>
#include <iphlpapi.h>
}

#pragma comment(lib, "iphlpapi.lib")

auto main() -> int {
  IP_ADAPTER_INFO* adapter_info = nullptr;
  ULONG buf_size = 0;

  // Make an initial call to GetAdaptersInfo to get
  // the necessary size into the buf_size variable
  if (GetAdaptersInfo(nullptr, &buf_size) == ERROR_BUFFER_OVERFLOW) {
    adapter_info = static_cast<IP_ADAPTER_INFO*>(std::malloc(buf_size));
  }

  if (GetAdaptersInfo(adapter_info, &buf_size) == NO_ERROR) {
    for (auto adapter = adapter_info; adapter; adapter = adapter->Next) {
      if (adapter->Type == MIB_IF_TYPE_ETHERNET || IF_TYPE_IEEE80211) {
        std::cout << "Adapter Name:\t" << adapter->AdapterName << "\n"
                  << "Adapter Desc:\t" << adapter->Description << "\n";
        std::cout << "Adapter Addr:\t" << std::hex;
        for (std::size_t i = 0; i < adapter->AddressLength; ++i) {
          if (i == (adapter->AddressLength - 1)) {
            std::cout << static_cast<int>(adapter->Address[i]) << "\n";
          } else {
            std::cout << static_cast<int>(adapter->Address[i]) << "-";
          }
        }
        std::cout << "IP Addr:\t" << adapter->IpAddressList.IpAddress.String << "\n"
                  << "IP Mask:\t" << adapter->IpAddressList.IpMask.String    << "\n"
                  << "Gateway:\t" << adapter->GatewayList.IpAddress.String   << "\n";
      }
      std::cout << "--------------------------------" << std::endl;
    }
  }

  std::free(adapter_info);
}