如何从SOCKADDR结构获取IPv4地址？

Question

我无法弄清楚如何从IP_ADAPTER_UNICAST_ADDRESS_LH结构的“ Address字段中获取实际的IP v4地址（例如192.168.1.1或其对应的打包形式为32位整数）。 我沿着链接列表和相应的MSDN链接的“兔子洞”走了，但是SOCKADDR是它的SOCKADDR 。 SOCKADDR是通用数据持有者，必须将其强制转换为IPv4变体才能获得数据的结构化视图。

麻烦的是，我找不到SOCKADDR的IPv4映射是哪种结构。 尝试了in_addr ，获取垃圾值。

auto pAddresses = static_cast<IP_ADAPTER_ADDRESSES*>(malloc(defaultBufferSize));
    ULONG outBufLen = defaultBufferSize;
    constexpr ULONG flags = GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME;
    auto result = GetAdaptersAddresses(AF_INET /* Only IP v4 since no cameras use v6 yet */, flags, nullptr, pAddresses, &outBufLen);

    uint32_t ipV4Address = 0;

    // Iterating over the returned adapter info structures
    for (auto currentInterfaceInfo = pAddresses; currentInterfaceInfo != nullptr; currentInterfaceInfo = currentInterfaceInfo->Next)
    {
        if (currentInterfaceInfo->IfType != IF_TYPE_IEEE80211 || currentInterfaceInfo->Ipv4Enabled != 1 || currentInterfaceInfo->ReceiveOnly != 0)
            continue;

        if (currentInterfaceInfo->FirstUnicastAddress)
        {
            for (auto addressInfo = currentInterfaceInfo->FirstUnicastAddress; addressInfo != nullptr; addressInfo = currentInterfaceInfo->FirstUnicastAddress->Next)
            {
                if (!addressInfo->Address.lpSockaddr || addressInfo->Address.lpSockaddr->sa_family != AF_INET /* IP v4 */)
                    continue;

                auto ipv4AddrInfo = reinterpret_cast<in_addr*>(addressInfo->Address.lpSockaddr);
                                                     ^^^^????
            }
        }
    }

Answer 1

给定SOCKADDR* ，请查看其sa_family字段以确定地址类型。

• 对于AF_INET地址，将SOCKADDR*转换为SOCKADDR_IN* ，然后可以访问其sin_addr字段。

• 对于AF_INET6地址，将SOCKADDR*转换为SOCKADDR_IN6* ，然后可以访问其sin6_addr字段。

std::vector<BYTE> buffer(defaultBufferSize);
auto pAddresses = reinterpret_cast<IP_ADAPTER_ADDRESSES*>(buffer.data());
ULONG outBufLen = defaultBufferSize;

constexpr ULONG flags = GAA_FLAG_SKIP_ANYCAST | GAA_FLAG_SKIP_MULTICAST | GAA_FLAG_SKIP_DNS_SERVER | GAA_FLAG_SKIP_FRIENDLY_NAME;
auto result = GetAdaptersAddresses(AF_INET /* Only IP v4 since no cameras use v6 yet */, flags, nullptr, pAddresses, &outBufLen);

uint32_t ipV4Address = 0;

// Iterating over the returned adapter info structures
for (auto currentInterfaceInfo = pAddresses; currentInterfaceInfo != nullptr; currentInterfaceInfo = currentInterfaceInfo->Next)
{
    if (currentInterfaceInfo->IfType != IF_TYPE_IEEE80211 || currentInterfaceInfo->Ipv4Enabled != 1 || currentInterfaceInfo->ReceiveOnly != 0)
        continue;

    for (auto addressInfo = currentInterfaceInfo->FirstUnicastAddress; addressInfo != nullptr; addressInfo = addressInfo->Next)
    {
        if (!addressInfo->Address.lpSockaddr || addressInfo->Address.lpSockaddr->sa_family != AF_INET /* IP v4 */)
            continue;

        auto ipv4AddrInfo = reinterpret_cast<sockaddr_in*>(addressInfo->Address.lpSockaddr);
        // use ipv4AddrInfo->sin_addr as needed...
    }
}