# This file is part of Scapy
# See http://www.secdev.org/projects/scapy for more information
# Copyright (C) Nils Weiss <nils@we155.de>
# This program is published under a GPLv2 license

# scapy.contrib.description = ISO-TP (ISO 15765-2) Native Socket Library
# scapy.contrib.status = library

import ctypes
from ctypes.util import find_library
import struct
import socket

from scapy.compat import Optional, Union, Tuple, Type, cast
from scapy.packet import Packet
import scapy.modules.six as six
from scapy.error import Scapy_Exception, warning
from scapy.supersocket import SuperSocket
from scapy.data import SO_TIMESTAMPNS
from scapy.config import conf
from scapy.arch.linux import get_last_packet_timestamp, SIOCGIFINDEX
from scapy.contrib.isotp.isotp_packet import ISOTP
from scapy.layers.can import CAN_MTU, CAN_MAX_DLEN


LIBC = ctypes.cdll.LoadLibrary(find_library("c"))  # type: ignore

CAN_ISOTP = 6  # ISO 15765-2 Transport Protocol

SOL_CAN_BASE = 100  # from can.h
SOL_CAN_ISOTP = SOL_CAN_BASE + CAN_ISOTP
# /* for socket options affecting the socket (not the global system) */
CAN_ISOTP_OPTS = 1  # /* pass struct can_isotp_options */
CAN_ISOTP_RECV_FC = 2  # /* pass struct can_isotp_fc_options */

# /* sockopts to force stmin timer values for protocol regression tests */
CAN_ISOTP_TX_STMIN = 3  # /* pass __u32 value in nano secs    */
CAN_ISOTP_RX_STMIN = 4  # /* pass __u32 value in nano secs   */
CAN_ISOTP_LL_OPTS = 5  # /* pass struct can_isotp_ll_options */

CAN_ISOTP_LISTEN_MODE = 0x001  # /* listen only (do not send FC) */
CAN_ISOTP_EXTEND_ADDR = 0x002  # /* enable extended addressing */
CAN_ISOTP_TX_PADDING = 0x004  # /* enable CAN frame padding tx path */
CAN_ISOTP_RX_PADDING = 0x008  # /* enable CAN frame padding rx path */
CAN_ISOTP_CHK_PAD_LEN = 0x010  # /* check received CAN frame padding */
CAN_ISOTP_CHK_PAD_DATA = 0x020  # /* check received CAN frame padding */
CAN_ISOTP_HALF_DUPLEX = 0x040  # /* half duplex error state handling */
CAN_ISOTP_FORCE_TXSTMIN = 0x080  # /* ignore stmin from received FC */
CAN_ISOTP_FORCE_RXSTMIN = 0x100  # /* ignore CFs depending on rx stmin */
CAN_ISOTP_RX_EXT_ADDR = 0x200  # /* different rx extended addressing */

# /* default values */
CAN_ISOTP_DEFAULT_FLAGS = 0
CAN_ISOTP_DEFAULT_EXT_ADDRESS = 0x00
CAN_ISOTP_DEFAULT_PAD_CONTENT = 0xCC  # /* prevent bit-stuffing */
CAN_ISOTP_DEFAULT_FRAME_TXTIME = 0
CAN_ISOTP_DEFAULT_RECV_BS = 0
CAN_ISOTP_DEFAULT_RECV_STMIN = 0x00
CAN_ISOTP_DEFAULT_RECV_WFTMAX = 0
CAN_ISOTP_DEFAULT_LL_MTU = CAN_MTU
CAN_ISOTP_DEFAULT_LL_TX_DL = CAN_MAX_DLEN
CAN_ISOTP_DEFAULT_LL_TX_FLAGS = 0


class tp(ctypes.Structure):
    # This struct is only used within the sockaddr_can struct
    _fields_ = [("rx_id", ctypes.c_uint32),
                ("tx_id", ctypes.c_uint32)]


class addr_info(ctypes.Union):
    # This struct is only used within the sockaddr_can struct
    # This union is to future proof for future can address information
    _fields_ = [("tp", tp)]


class sockaddr_can(ctypes.Structure):
    # See /usr/include/linux/can.h for original struct
    _fields_ = [("can_family", ctypes.c_uint16),
                ("can_ifindex", ctypes.c_int),
                ("can_addr", addr_info)]


class ifreq(ctypes.Structure):
    # The two fields in this struct were originally unions.
    # See /usr/include/net/if.h for original struct
    _fields_ = [("ifr_name", ctypes.c_char * 16),
                ("ifr_ifindex", ctypes.c_int)]


class ISOTPNativeSocket(SuperSocket):
    desc = "read/write packets at a given CAN interface using CAN_ISOTP socket "  # noqa: E501
    can_isotp_options_fmt = "@2I4B"
    can_isotp_fc_options_fmt = "@3B"
    can_isotp_ll_options_fmt = "@3B"
    sockaddr_can_fmt = "@H3I"
    auxdata_available = True

    def __build_can_isotp_options(
            self,
            flags=CAN_ISOTP_DEFAULT_FLAGS,
            frame_txtime=CAN_ISOTP_DEFAULT_FRAME_TXTIME,
            ext_address=CAN_ISOTP_DEFAULT_EXT_ADDRESS,
            txpad_content=CAN_ISOTP_DEFAULT_PAD_CONTENT,
            rxpad_content=CAN_ISOTP_DEFAULT_PAD_CONTENT,
            rx_ext_address=CAN_ISOTP_DEFAULT_EXT_ADDRESS):
        # type: (int, int, int, int, int, int) -> bytes
        return struct.pack(self.can_isotp_options_fmt,
                           flags,
                           frame_txtime,
                           ext_address,
                           txpad_content,
                           rxpad_content,
                           rx_ext_address)

    # == Must use native not standard types for packing ==
    # struct can_isotp_options {
    # __u32 flags;            /* set flags for isotp behaviour.       */
    #                         /* __u32 value : flags see below        */
    #
    # __u32 frame_txtime;     /* frame transmission time (N_As/N_Ar)  */
    #                       /* __u32 value : time in nano secs      */
    #
    # __u8  ext_address;      /* set address for extended addressing  */
    #                         /* __u8 value : extended address        */
    #
    # __u8  txpad_content;    /* set content of padding byte (tx)     */
    #                         /* __u8 value : content on tx path      */
    #
    # __u8  rxpad_content;    /* set content of padding byte (rx)     */
    #                         /* __u8 value : content on rx path      */
    #
    # __u8  rx_ext_address;   /* set address for extended addressing  */
    #                         /* __u8 value : extended address (rx)   */
    # };

    def __build_can_isotp_fc_options(self,
                                     bs=CAN_ISOTP_DEFAULT_RECV_BS,
                                     stmin=CAN_ISOTP_DEFAULT_RECV_STMIN,
                                     wftmax=CAN_ISOTP_DEFAULT_RECV_WFTMAX):
        # type: (int, int, int) -> bytes
        return struct.pack(self.can_isotp_fc_options_fmt,
                           bs,
                           stmin,
                           wftmax)

    # == Must use native not standard types for packing ==
    # struct can_isotp_fc_options {
    #
    # __u8  bs;               /* blocksize provided in FC frame       */
    #                         /* __u8 value : blocksize. 0 = off      */
    #
    # __u8  stmin;            /* separation time provided in FC frame */
    #                         /* __u8 value :                         */
    #                         /* 0x00 - 0x7F : 0 - 127 ms             */
    #                         /* 0x80 - 0xF0 : reserved               */
    #                         /* 0xF1 - 0xF9 : 100 us - 900 us        */
    #                         /* 0xFA - 0xFF : reserved               */
    #
    # __u8  wftmax;           /* max. number of wait frame transmiss. */
    #                         /* __u8 value : 0 = omit FC N_PDU WT    */
    # };

    def __build_can_isotp_ll_options(self,
                                     mtu=CAN_ISOTP_DEFAULT_LL_MTU,
                                     tx_dl=CAN_ISOTP_DEFAULT_LL_TX_DL,
                                     tx_flags=CAN_ISOTP_DEFAULT_LL_TX_FLAGS
                                     ):
        # type: (int, int, int) -> bytes
        return struct.pack(self.can_isotp_ll_options_fmt,
                           mtu,
                           tx_dl,
                           tx_flags)

    # == Must use native not standard types for packing ==
    # struct can_isotp_ll_options {
    #
    # __u8  mtu;              /* generated & accepted CAN frame type  */
    #                         /* __u8 value :                         */
    #                         /* CAN_MTU   (16) -> standard CAN 2.0   */
    #                         /* CANFD_MTU (72) -> CAN FD frame       */
    #
    # __u8  tx_dl;            /* tx link layer data length in bytes   */
    #                         /* (configured maximum payload length)  */
    #                         /* __u8 value : 8,12,16,20,24,32,48,64  */
    #                         /* => rx path supports all LL_DL values */
    #
    # __u8  tx_flags;         /* set into struct canfd_frame.flags    */
    #                         /* at frame creation: e.g. CANFD_BRS    */
    #                         /* Obsolete when the BRS flag is fixed  */
    #                         /* by the CAN netdriver configuration   */
    # };

    def __get_sock_ifreq(self, sock, iface):
        # type: (socket.socket, str) -> ifreq
        socket_id = ctypes.c_int(sock.fileno())
        ifr = ifreq()
        ifr.ifr_name = iface.encode('ascii')
        ret = LIBC.ioctl(socket_id, SIOCGIFINDEX, ctypes.byref(ifr))

        if ret < 0:
            m = u'Failure while getting "{}" interface index.'.format(
                iface)
            raise Scapy_Exception(m)
        return ifr

    def __bind_socket(self, sock, iface, sid, did):
        # type: (socket.socket, str, int, int) -> None
        socket_id = ctypes.c_int(sock.fileno())
        ifr = self.__get_sock_ifreq(sock, iface)

        if sid > 0x7ff:
            sid = sid | socket.CAN_EFF_FLAG
        if did > 0x7ff:
            did = did | socket.CAN_EFF_FLAG

        # select the CAN interface and bind the socket to it
        addr = sockaddr_can(ctypes.c_uint16(socket.PF_CAN),
                            ifr.ifr_ifindex,
                            addr_info(tp(ctypes.c_uint32(did),
                                         ctypes.c_uint32(sid))))

        error = LIBC.bind(socket_id, ctypes.byref(addr),
                          ctypes.sizeof(addr))

        if error < 0:
            warning("Couldn't bind socket")

    def __set_option_flags(self,
                           sock,  # type: socket.socket
                           extended_addr=None,  # type: Optional[int]
                           extended_rx_addr=None,  # type: Optional[int]
                           listen_only=False,  # type: bool
                           padding=False,  # type: bool
                           transmit_time=100  # type: int
                           ):
        # type: (...) -> None
        option_flags = CAN_ISOTP_DEFAULT_FLAGS
        if extended_addr is not None:
            option_flags = option_flags | CAN_ISOTP_EXTEND_ADDR
        else:
            extended_addr = CAN_ISOTP_DEFAULT_EXT_ADDRESS

        if extended_rx_addr is not None:
            option_flags = option_flags | CAN_ISOTP_RX_EXT_ADDR
        else:
            extended_rx_addr = CAN_ISOTP_DEFAULT_EXT_ADDRESS

        if listen_only:
            option_flags = option_flags | CAN_ISOTP_LISTEN_MODE

        if padding:
            option_flags = option_flags | CAN_ISOTP_TX_PADDING | CAN_ISOTP_RX_PADDING  # noqa: E501

        sock.setsockopt(SOL_CAN_ISOTP,
                        CAN_ISOTP_OPTS,
                        self.__build_can_isotp_options(
                            frame_txtime=transmit_time,
                            flags=option_flags,
                            ext_address=extended_addr,
                            rx_ext_address=extended_rx_addr))

    def __init__(self,
                 iface=None,  # type: Optional[Union[str, SuperSocket]]
                 tx_id=0,  # type: int
                 rx_id=0,  # type: int
                 ext_address=None,  # type: Optional[int]
                 rx_ext_address=None,  # type: Optional[int]
                 listen_only=False,  # type: bool
                 padding=False,  # type: bool
                 frame_txtime=100,  # type: int
                 stmin=0,  # type: int
                 basecls=ISOTP  # type: Type[Packet]
                 ):
        # type: (...) -> None

        if not isinstance(iface, six.string_types):
            # This is for interoperability with ISOTPSoftSockets.
            # If a NativeCANSocket is provided, the interface name of this
            # socket is extracted and an ISOTPNativeSocket will be opened
            # on this interface.
            iface = cast(SuperSocket, iface)
            if hasattr(iface, "ins") and hasattr(iface.ins, "getsockname"):
                iface = iface.ins.getsockname()
                if isinstance(iface, tuple):
                    iface = cast(str, iface[0])
            else:
                raise Scapy_Exception("Provide a string or a CANSocket "
                                      "object as iface parameter")

        self.iface = cast(str, iface) or conf.contribs['NativeCANSocket']['iface']  # noqa: E501
        self.can_socket = socket.socket(socket.PF_CAN, socket.SOCK_DGRAM,
                                        CAN_ISOTP)
        self.__set_option_flags(self.can_socket,
                                ext_address,
                                rx_ext_address,
                                listen_only,
                                padding,
                                frame_txtime)

        self.tx_id = tx_id
        self.rx_id = rx_id
        self.ext_address = ext_address
        self.rx_ext_address = rx_ext_address

        self.can_socket.setsockopt(SOL_CAN_ISOTP,
                                   CAN_ISOTP_RECV_FC,
                                   self.__build_can_isotp_fc_options(
                                       stmin=stmin))
        self.can_socket.setsockopt(SOL_CAN_ISOTP,
                                   CAN_ISOTP_LL_OPTS,
                                   self.__build_can_isotp_ll_options())
        self.can_socket.setsockopt(
            socket.SOL_SOCKET,
            SO_TIMESTAMPNS,
            1
        )

        self.__bind_socket(self.can_socket, self.iface, tx_id, rx_id)
        self.ins = self.can_socket
        self.outs = self.can_socket
        if basecls is None:
            warning('Provide a basecls ')
        self.basecls = basecls

    def recv_raw(self, x=0xffff):
        # type: (int) -> Tuple[Optional[Type[Packet]], Optional[bytes], Optional[float]]  # noqa: E501
        """
        Receives a packet, then returns a tuple containing
        (cls, pkt_data, time)
        """
        try:
            pkt, _, ts = self._recv_raw(self.ins, x)
        except BlockingIOError:  # noqa: F821
            warning('Captured no data, socket in non-blocking mode.')
            return None, None, None
        except socket.timeout:
            warning('Captured no data, socket read timed out.')
            return None, None, None
        except OSError as e:
            # something bad happened (e.g. the interface went down)
            warning("Captured no data. %s" % e)
            if e.errno == 84:
                warning("Maybe a consecutive frame was missed. "
                        "Increasing `stmin` could solve this problem.")
            elif e.errno == 110:
                warning('Captured no data, socket read timed out.')
            else:
                self.close()
            return None, None, None

        if ts is None:
            ts = get_last_packet_timestamp(self.ins)
        return self.basecls, pkt, ts

    def recv(self, x=0xffff):
        # type: (int) -> Optional[Packet]
        msg = SuperSocket.recv(self, x)
        if msg is None:
            return msg

        if hasattr(msg, "tx_id"):
            msg.tx_id = self.tx_id
        if hasattr(msg, "rx_id"):
            msg.rx_id = self.rx_id
        if hasattr(msg, "ext_address"):
            msg.ext_address = self.ext_address
        if hasattr(msg, "rx_ext_address"):
            msg.rx_ext_address = self.rx_ext_address
        return msg
