Windows GetAdaptersAddresses test

windows_get_adapters_addresses.cpp

#include <winsock2.h>

// Must be included after winsock2.h
#include <iphlpapi.h>

#include <cassert>
#include <format>
#include <iostream>

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

namespace {
std::string Utf8FromUtf16(std::wstring_view utf16_string) {
  if (utf16_string.empty()) {
    return {};
  }

  auto src_length = static_cast<int>(utf16_string.size());
  int target_length =
      ::WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string.data(),
                            src_length, nullptr, 0, nullptr, nullptr);

  std::string utf8_string;
  if (target_length <= 0 || target_length > utf8_string.max_size()) {
    return utf8_string;
  }
  utf8_string.resize(target_length);
  int converted_length = ::WideCharToMultiByte(
      CP_UTF8, WC_ERR_INVALID_CHARS, utf16_string.data(), src_length,
      utf8_string.data(), target_length, nullptr, nullptr);
  if (converted_length == 0) {
    return {};
  }
  return utf8_string;
}

std::string FamilyToString(int family) {
  switch (family) {
    case AF_INET:
      return "AF_INET";
    case AF_INET6:
      return "AF_INET6";
    case AF_UNSPEC:
      return "AF_UNSPEC";
    default:
      return "unknown";
  }
}

void GetAddresses(int type) {
  ULONG size = 0;
  DWORD flags = GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST |
                GAA_FLAG_SKIP_DNS_SERVER;
  auto status = GetAdaptersAddresses(type, flags, nullptr, nullptr, &size);

  IP_ADAPTER_ADDRESSES* addrs = nullptr;
  if (status == ERROR_BUFFER_OVERFLOW) {
    addrs = reinterpret_cast<IP_ADAPTER_ADDRESSES*>(malloc(size));
    // Get the addresses now we have the right buffer.
    status = GetAdaptersAddresses(type, flags, nullptr, addrs, &size);
  }

  for (IP_ADAPTER_ADDRESSES* a = addrs; a != nullptr; a = a->Next) {
    for (IP_ADAPTER_UNICAST_ADDRESS* u = a->FirstUnicastAddress; u != nullptr;
         u = u->Next) {
      assert(
          type == AF_UNSPEC ||
          (type == AF_INET && u->Address.lpSockaddr->sa_family == AF_INET) ||
          (type == AF_INET6 && u->Address.lpSockaddr->sa_family == AF_INET6));
      
      assert((a->Flags & IP_ADAPTER_IPV4_ENABLED && a->IfIndex != 0) ||
             (a->Flags & IP_ADAPTER_IPV6_ENABLED && a->Ipv6IfIndex != 0));
      
      assert(a->IfIndex == a->Ipv6IfIndex ||
             !!(a->Flags & IP_ADAPTER_IPV4_ENABLED) !=
                 !!(a->Flags & IP_ADAPTER_IPV6_ENABLED));
      
      assert(type != AF_INET || a->Flags & IP_ADAPTER_IPV4_ENABLED);
      assert(type != AF_INET6 || a->Flags & IP_ADAPTER_IPV6_ENABLED);

      assert(a->IfIndex == a->Ipv6IfIndex ||
             (!(a->Flags & IP_ADAPTER_IPV4_ENABLED) ||
              !(a->Flags & IP_ADAPTER_IPV6_ENABLED)));

      std::cout << std::format("'{}' -> family={}, ifIndex={}, Ipv6IfIndex={}",
                               Utf8FromUtf16(a->FriendlyName),
                               FamilyToString(u->Address.lpSockaddr->sa_family),
                               a->IfIndex, a->Ipv6IfIndex)
                << std::endl;
    }
  }
  free(addrs);
}

void DumpAddresses(int family) {
  std::cout << std::format("----{}----", FamilyToString(family)) << std::endl;
  GetAddresses(family);
  std::cout << std::endl << std::endl;
}

}  // namespace

int main() {
  DumpAddresses(AF_INET);
  DumpAddresses(AF_INET6);
  DumpAddresses(AF_UNSPEC);
}

IPv4 + IPv6 enabled

----AF_INET----
'Ethernet 4' -> family=AF_INET, ifIndex=23, Ipv6IfIndex=23


----AF_INET6----
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23


----AF_UNSPEC----
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET, ifIndex=23, Ipv6IfIndex=23

IPv4 turned off

----AF_INET----


----AF_INET6----
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23


----AF_UNSPEC----
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23
'Ethernet 4' -> family=AF_INET6, ifIndex=23, Ipv6IfIndex=23

IPv6 turned off

----AF_INET----
'Ethernet 4' -> family=AF_INET, ifIndex=23, Ipv6IfIndex=0


----AF_INET6----


----AF_UNSPEC----
'Ethernet 4' -> family=AF_INET, ifIndex=23, Ipv6IfIndex=0

Both IPv4 and IPv6 turned off

----AF_INET----



----AF_INET6----



----AF_UNSPEC----