import socket, ctypes

# Python socket module does not have this constant
DIOCNATLOOK = 23
PFDEV = "/dev/pf"


class PF_STATE_XPORT(ctypes.Union):
    """
        union pf_state_xport {
            u_int16_t	port;
            u_int16_t	call_id;
            u_int32_t	spi;
        };
    """
    _fields_ = [
        ("port", ctypes.c_uint),
        ("call_id", ctypes.c_uint),
        ("spi", ctypes.c_ulong),
    ]


class PF_ADDR(ctypes.Union):
    """
        struct pf_addr {
            union {
                struct in_addr		v4;
                struct in6_addr		v6;
                u_int8_t		addr8[16];
                u_int16_t		addr16[8];
                u_int32_t		addr32[4];
            } pfa;
        }
    """
    _fields_ = [
        ("addr8", ctypes.c_byte * 2),
        ("addr16", ctypes.c_byte * 4),
        ("addr32", ctypes.c_byte * 8),
    ]


class PFIOC_NATLOOK(ctypes.Structure):
    """
        struct pfioc_natlook {
            struct pf_addr	 saddr;
            struct pf_addr	 daddr;
            struct pf_addr	 rsaddr;
            struct pf_addr	 rdaddr;
        #ifndef NO_APPLE_EXTENSIONS
            union pf_state_xport	sxport;
            union pf_state_xport	dxport;
            union pf_state_xport	rsxport;
            union pf_state_xport	rdxport;
            sa_family_t	 af;
            u_int8_t	 proto;
            u_int8_t	 proto_variant;
            u_int8_t	 direction;
        #else
            u_int16_t	 sport;
            u_int16_t	 dport;
            u_int16_t	 rsport;
            u_int16_t	 rdport;
            sa_family_t	 af;
            u_int8_t	 proto;
            u_int8_t	 direction;
        #endif
        };
    """
    _fields_ = [
        ("saddr", PF_ADDR),
        ("daddr", PF_ADDR),
        ("rsaddr", PF_ADDR),
        ("rdaddr", PF_ADDR),

        ("sxport", PF_STATE_XPORT),
        ("dxport", PF_STATE_XPORT),
        ("rsxport", PF_STATE_XPORT),
        ("rdxport", PF_STATE_XPORT),
        ("af", ctypes.c_uint),
        ("proto", ctypes.c_ushort),
        ("proto_variant", ctypes.c_ushort),
        ("direction", ctypes.c_ushort),
    ]


class Resolver:
    def __init__(self):
        self.pfdev = open(PFDEV, "r")

    def original_addr(self, csock):
        """
            The following sttruct defintions are plucked from the current XNU source, found here:

                http://www.opensource.apple.com/source/xnu/xnu-1699.26.8/bsd/net/pfvar.h


            union pf_state_xport {
                u_int16_t	port;
                u_int16_t	call_id;
                u_int32_t	spi;
            };
        """
        pass