優先ローカル UDP マルチプレイヤー ポート ネットワーキング API

HRESULT
CreateAndBindMultiplayerSocket(
    _Out_ SOCKET* multiplayerSocket
    )
{
    HRESULT hr;
    SOCKET resultSocket = INVALID_SOCKET;

    uint16_t port;
    hr = XNetworkingQueryPreferredLocalUdpMultiplayerPort(&port);
    if (FAILED(hr))
    {
        goto Failure;
    }

    resultSocket = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
    if (resultSocket == INVALID_SOCKET)
    {
        hr = HRESULT_FROM_WIN32(WSAGetLastError());
        goto Failure;
    }

    // Enable both IPv4 and IPv6 on this socket.
    int v6only = 0;
    if (setsockopt(resultSocket, IPPROTO_IPV6, IPV6_V6ONLY, (char*)&v6only, sizeof(v6only)) == SOCKET_ERROR)
    {
        hr = HRESULT_FROM_WIN32(WSAGetLastError());
        goto Failure;
    }

    sockaddr_in6 sa;
    ZeroMemory(&sa, sizeof(sa));
    sa.sin6_family = AF_INET6;
    sa.sin6_port = htons(port);
    sa.sin6_addr = in6addr_any;
    if (bind(resultSocket, (const sockaddr*)&sa, sizeof(sa)) == SOCKET_ERROR)
    {
        hr = HRESULT_FROM_WIN32(WSAGetLastError());
        goto Failure;
    }

    *multiplayerSocket = resultSocket;

Exit:

    return hr;

Failure:

    if (resultSocket != INVALID_SOCKET)
    {
        (void)closesocket(resultSocket);
    }

    goto Exit;
}