Python-сообщество

class in_addr(Structure):
    pass
uint32_t = c_uint32
in_addr_t = uint32_t
in_addr._fields_ = [
    ('s_addr', in_addr_t),
]

class sockaddr(Structure):
    pass
sockaddr._fields_ = [
    ('sa_family', sa_family_t),
    ('sa_data', c_char * 14),
]

class sockaddr_in(Structure):
    pass
sockaddr_in._fields_ = [
    ('sin_family', sa_family_t),
    ('sin_port', in_port_t),
    ('sin_addr', in_addr),
    ('sin_zero', c_ubyte * 8),
]

    saddr = libname.sockaddr_in()
    saddr.sin_family = socket.AF_INET
    saddr.sin_addr.s_addr = socket.htonl(0x7f000001)
    saddr.sin_port = socket.htons(3000)
    result = CFunction(saddr, sys.getsizeof(saddr))

    sptr = ctypes.pointer(saddr)
    sa = ctypes.cast(sptr, ctypes.POINTER(lib.sockaddr))[0]