inet_pton monkey patch for windows

inet_pton.py

import socket
if not hasattr(socket, "inet_pton"):  # pragma: no cover
    import ctypes

    WSAStringToAddressA = ctypes.windll.ws2_32.WSAStringToAddressA

    class sockaddr(ctypes.Structure):
        _fields_ = [
            ("sa_family", ctypes.c_short),
            ("__pad1", ctypes.c_ushort),
            ("ipv4_addr", ctypes.c_byte * 4),
            ("ipv6_addr", ctypes.c_byte * 16),
            ("__pad2", ctypes.c_ulong)
        ]

    def inet_pton(address_family, ip_string):
        addr = sockaddr()
        addr.sa_family = address_family
        addr_size = ctypes.c_int(ctypes.sizeof(addr))

        if WSAStringToAddressA(ip_string, address_family, None, ctypes.byref(addr), ctypes.byref(addr_size)) != 0:
            raise socket.error(ctypes.FormatError())

        if address_family == socket.AF_INET:
            return ctypes.string_at(addr.ipv4_addr, 4)
        elif address_family == socket.AF_INET6:
            return ctypes.string_at(addr.ipv6_addr, 16)
        else:
            raise socket.error('unknown address family')

    setattr(socket, "inet_pton", inet_pton)