Return a list of network interfaces info, with this format:

    {
        'interface_name':
            {
                'ipv6': [{'scope': 5L,
                          'netmask': 'ffff:ffff:ffff:ffff::',
                          'addr': 'fe80::34f2:7dff:fe69:7c18'}],
                'hw': [{'addr': '36:f2:7d:69:7c:18'}],
                'ipv4': [{'netmask': '255.255.255.0', 'addr': '10.0.3.1'}]},
            },
        ...
    }

def getifaddrs():
    """
    Return a list of network interfaces info, with this format:

    {
        'interface_name':
            {
                'ipv6': [{'scope': 5L,
                          'netmask': 'ffff:ffff:ffff:ffff::',
                          'addr': 'fe80::34f2:7dff:fe69:7c18'}],
                'hw': [{'addr': '36:f2:7d:69:7c:18'}],
                'ipv4': [{'netmask': '255.255.255.0', 'addr': '10.0.3.1'}]},
            },
        ...
    }
    """
    class ifa_ifu_u(Union):
        _fields_ = [
            ("ifu_broadaddr", c_void_p),
            ("ifu_dstaddr", c_void_p)
        ]

    class ifaddrs(Structure):
        _fields_ = [
            ("ifa_next", c_void_p),
            ("ifa_name", c_char_p),
            ("ifa_flags", c_uint),
            ("ifa_addr", c_void_p),
            ("ifa_netmask", c_void_p),
            ("ifa_ifu", ifa_ifu_u),
            ("ifa_data", c_void_p)
        ]

    # AF_UNKNOWN / generic
    if platform.startswith("darwin") or platform.startswith("freebsd"):
        class sockaddr(Structure):
            _fields_ = [
                ("sa_len", c_uint8),
                ("sa_family", c_uint8),
                ("sa_data", c_uint8 * 14)
            ]
    else:
        class sockaddr(Structure):
            _fields_ = [
                ("sa_family", c_uint16),
                ("sa_data", c_uint8 * 14)
            ]

    # AF_INET / IPv4
    class in_addr(Union):
        _fields_ = [
            ("s_addr", c_uint32),
        ]

    class sockaddr_in(Structure):
        _fields_ = [
            ("sin_family", c_short),
            ("sin_port", c_ushort),
            ("sin_addr", in_addr),
            ("sin_zero", c_char * 8),  # padding
        ]

    # AF_INET6 / IPv6
    class in6_u(Union):
        _fields_ = [
            ("u6_addr8", c_uint8 * 16),
            ("u6_addr16", c_uint16 * 8),
            ("u6_addr32", c_uint32 * 4)
        ]

    class in6_addr(Union):
        _fields_ = [
            ("in6_u", in6_u),
        ]

    class sockaddr_in6(Structure):
        _fields_ = [
            ("sin6_family", c_short),
            ("sin6_port", c_ushort),
            ("sin6_flowinfo", c_uint32),
            ("sin6_addr", in6_addr),
            ("sin6_scope_id", c_uint32),
        ]

    # AF_PACKET / Linux
    class sockaddr_ll(Structure):
        _fields_ = [
            ("sll_family", c_uint16),
            ("sll_protocol", c_uint16),
            ("sll_ifindex", c_uint32),
            ("sll_hatype", c_uint16),
            ("sll_pktype", c_uint8),
            ("sll_halen", c_uint8),
            ("sll_addr", c_uint8 * 8)
        ]

    # AF_LINK / BSD|OSX
    class sockaddr_dl(Structure):
        _fields_ = [
            ("sdl_len", c_uint8),
            ("sdl_family", c_uint8),
            ("sdl_index", c_uint16),
            ("sdl_type", c_uint8),
            ("sdl_nlen", c_uint8),
            ("sdl_alen", c_uint8),
            ("sdl_slen", c_uint8),
            ("sdl_data", c_uint8 * 46)
        ]

    families = {
        AF_INET: 'ipv4',
        AF_INET6: 'ipv6',
        AF_PACKET: 'hw'
    }

    libc = CDLL("libc.so.6")
    ptr = c_void_p(None)
    result = libc.getifaddrs(pointer(ptr))
    if result:
        return None
    ifa = ifaddrs.from_address(ptr.value)
    result = {}

    while ifa:
        name = ifa.ifa_name
#       name = ifa.ifa_name.decode('UTF-8') # use this for python3

        if name not in result:
            result[name] = {}

        sa = sockaddr.from_address(ifa.ifa_addr)

        if sa.sa_family not in result[name]:
            result[name][families[sa.sa_family]] = []

        data = {}

        if sa.sa_family == AF_INET:
            if ifa.ifa_addr is not None:
                si = sockaddr_in.from_address(ifa.ifa_addr)
                data['addr'] = inet_ntop(si.sin_family, si.sin_addr)
            if ifa.ifa_netmask is not None:
                si = sockaddr_in.from_address(ifa.ifa_netmask)
                data['netmask'] = inet_ntop(si.sin_family, si.sin_addr)

        if sa.sa_family == AF_INET6:
            if ifa.ifa_addr is not None:
                si = sockaddr_in6.from_address(ifa.ifa_addr)
                data['addr'] = inet_ntop(si.sin6_family, si.sin6_addr)
                if data['addr'].startswith('fe80:'):
                    data['scope'] = si.sin6_scope_id
            if ifa.ifa_netmask is not None:
                si = sockaddr_in6.from_address(ifa.ifa_netmask)
                data['netmask'] = inet_ntop(si.sin6_family, si.sin6_addr)

        if sa.sa_family == AF_PACKET:
            if ifa.ifa_addr is not None:
                si = sockaddr_ll.from_address(ifa.ifa_addr)
                addr = ""
                for i in range(si.sll_halen):
                    addr += "%02x:" % si.sll_addr[i]
                addr = addr[:-1]
                data['addr'] = addr

        if len(data) > 0:
            result[name][families[sa.sa_family]].append(data)

        if ifa.ifa_next:
            ifa = ifaddrs.from_address(ifa.ifa_next)
        else:
            break

    libc.freeifaddrs(ptr)
    return result