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

"""
Linux specific functions.
"""

from __future__ import absolute_import


import array
from fcntl import ioctl
import os
from select import select
import socket
import struct
import time
import re

import subprocess

from scapy.compat import raw, plain_str
from scapy.consts import LOOPBACK_NAME, LINUX
import scapy.utils
import scapy.utils6
from scapy.packet import Packet, Padding
from scapy.config import conf
from scapy.data import MTU, ETH_P_ALL
from scapy.supersocket import SuperSocket
from scapy.error import warning, Scapy_Exception, \
    ScapyInvalidPlatformException
from scapy.arch.common import get_if, compile_filter
import scapy.modules.six as six
from scapy.modules.six.moves import range


# From bits/ioctls.h
SIOCGIFHWADDR = 0x8927          # Get hardware address
SIOCGIFADDR = 0x8915          # get PA address
SIOCGIFNETMASK = 0x891b          # get network PA mask
SIOCGIFNAME = 0x8910          # get iface name
SIOCSIFLINK = 0x8911          # set iface channel
SIOCGIFCONF = 0x8912          # get iface list
SIOCGIFFLAGS = 0x8913          # get flags
SIOCSIFFLAGS = 0x8914          # set flags
SIOCGIFINDEX = 0x8933          # name -> if_index mapping
SIOCGIFCOUNT = 0x8938          # get number of devices
SIOCGSTAMP = 0x8906          # get packet timestamp (as a timeval)

# From if.h
IFF_UP = 0x1               # Interface is up.
IFF_BROADCAST = 0x2        # Broadcast address valid.
IFF_DEBUG = 0x4            # Turn on debugging.
IFF_LOOPBACK = 0x8         # Is a loopback net.
IFF_POINTOPOINT = 0x10     # Interface is point-to-point link.
IFF_NOTRAILERS = 0x20      # Avoid use of trailers.
IFF_RUNNING = 0x40         # Resources allocated.
IFF_NOARP = 0x80           # No address resolution protocol.
IFF_PROMISC = 0x100        # Receive all packets.

# From netpacket/packet.h
PACKET_ADD_MEMBERSHIP = 1
PACKET_DROP_MEMBERSHIP = 2
PACKET_RECV_OUTPUT = 3
PACKET_RX_RING = 5
PACKET_STATISTICS = 6
PACKET_MR_MULTICAST = 0
PACKET_MR_PROMISC = 1
PACKET_MR_ALLMULTI = 2

# From bits/socket.h
SOL_PACKET = 263
# From asm/socket.h
SO_ATTACH_FILTER = 26

# From net/route.h
RTF_UP = 0x0001  # Route usable
RTF_REJECT = 0x0200

# From if_packet.h
PACKET_HOST = 0  # To us
PACKET_BROADCAST = 1  # To all
PACKET_MULTICAST = 2  # To group
PACKET_OTHERHOST = 3  # To someone else
PACKET_OUTGOING = 4  # Outgoing of any type
PACKET_LOOPBACK = 5  # MC/BRD frame looped back
PACKET_USER = 6  # To user space
PACKET_KERNEL = 7  # To kernel space
PACKET_FASTROUTE = 6  # Fastrouted frame
# Unused, PACKET_FASTROUTE and PACKET_LOOPBACK are invisible to user space


def get_if_raw_hwaddr(iff):
    return struct.unpack("16xh6s8x", get_if(iff, SIOCGIFHWADDR))


def get_if_raw_addr(iff):
    try:
        return get_if(iff, SIOCGIFADDR)[20:24]
    except IOError:
        return b"\0\0\0\0"


def get_if_list():
    try:
        f = open("/proc/net/dev", "rb")
    except IOError:
        f.close()
        warning("Can't open /proc/net/dev !")
        return []
    lst = []
    f.readline()
    f.readline()
    for line in f:
        line = plain_str(line)
        lst.append(line.split(":")[0].strip())
    f.close()
    return lst


def get_working_if():
    for i in get_if_list():
        if i == LOOPBACK_NAME:
            continue
        ifflags = struct.unpack("16xH14x", get_if(i, SIOCGIFFLAGS))[0]
        if ifflags & IFF_UP:
            return i
    return LOOPBACK_NAME


def attach_filter(sock, bpf_filter, iface):
    # XXX We generate the filter on the interface conf.iface
    # because tcpdump open the "any" interface and ppp interfaces
    # in cooked mode. As we use them in raw mode, the filter will not
    # work... one solution could be to use "any" interface and translate
    # the filter from cooked mode to raw mode
    # mode
    bp = compile_filter(bpf_filter, iface)
    sock.setsockopt(socket.SOL_SOCKET, SO_ATTACH_FILTER, bp)


def set_promisc(s, iff, val=1):
    mreq = struct.pack("IHH8s", get_if_index(iff), PACKET_MR_PROMISC, 0, b"")
    if val:
        cmd = PACKET_ADD_MEMBERSHIP
    else:
        cmd = PACKET_DROP_MEMBERSHIP
    s.setsockopt(SOL_PACKET, cmd, mreq)


def get_alias_address(iface_name, ip_mask, gw_str, metric):
    """
    Get the correct source IP address of an interface alias
    """

    # Detect the architecture
    if scapy.consts.IS_64BITS:
        offset, name_len = 16, 40
    else:
        offset, name_len = 32, 32

    # Retrieve interfaces structures
    sck = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    names = array.array('B', b'\0' * 4096)
    ifreq = ioctl(sck.fileno(), SIOCGIFCONF,
                  struct.pack("iL", len(names), names.buffer_info()[0]))

    # Extract interfaces names
    out = struct.unpack("iL", ifreq)[0]
    names = names.tobytes() if six.PY3 else names.tostring()
    names = [names[i:i + offset].split(b'\0', 1)[0] for i in range(0, out, name_len)]  # noqa: E501

    # Look for the IP address
    for ifname in names:
        # Only look for a matching interface name
        if not ifname.decode("utf8").startswith(iface_name):
            continue

        # Retrieve and convert addresses
        ifreq = ioctl(sck, SIOCGIFADDR, struct.pack("16s16x", ifname))
        ifaddr = struct.unpack(">I", ifreq[20:24])[0]
        ifreq = ioctl(sck, SIOCGIFNETMASK, struct.pack("16s16x", ifname))
        msk = struct.unpack(">I", ifreq[20:24])[0]

        # Get the full interface name
        ifname = plain_str(ifname)
        if ':' in ifname:
            ifname = ifname[:ifname.index(':')]
        else:
            continue

        # Check if the source address is included in the network
        if (ifaddr & msk) == ip_mask:
            sck.close()
            return (ifaddr & msk, msk, gw_str, ifname,
                    scapy.utils.ltoa(ifaddr), metric)

    sck.close()
    return


def read_routes():
    try:
        f = open("/proc/net/route", "rb")
    except IOError:
        warning("Can't open /proc/net/route !")
        return []
    routes = []
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        ifreq = ioctl(s, SIOCGIFADDR, struct.pack("16s16x", scapy.consts.LOOPBACK_NAME.encode("utf8")))  # noqa: E501
        addrfamily = struct.unpack("h", ifreq[16:18])[0]
        if addrfamily == socket.AF_INET:
            ifreq2 = ioctl(s, SIOCGIFNETMASK, struct.pack("16s16x", scapy.consts.LOOPBACK_NAME.encode("utf8")))  # noqa: E501
            msk = socket.ntohl(struct.unpack("I", ifreq2[20:24])[0])
            dst = socket.ntohl(struct.unpack("I", ifreq[20:24])[0]) & msk
            ifaddr = scapy.utils.inet_ntoa(ifreq[20:24])
            routes.append((dst, msk, "0.0.0.0", scapy.consts.LOOPBACK_NAME, ifaddr, 1))  # noqa: E501
        else:
            warning("Interface %s: unknown address family (%i)" % (scapy.consts.LOOPBACK_NAME, addrfamily))  # noqa: E501
    except IOError as err:
        if err.errno == 99:
            warning("Interface %s: no address assigned" % scapy.consts.LOOPBACK_NAME)  # noqa: E501
        else:
            warning("Interface %s: failed to get address config (%s)" % (scapy.consts.LOOPBACK_NAME, str(err)))  # noqa: E501

    for line in f.readlines()[1:]:
        line = plain_str(line)
        iff, dst, gw, flags, _, _, metric, msk, _, _, _ = line.split()
        flags = int(flags, 16)
        if flags & RTF_UP == 0:
            continue
        if flags & RTF_REJECT:
            continue
        try:
            ifreq = ioctl(s, SIOCGIFADDR, struct.pack("16s16x", iff.encode("utf8")))  # noqa: E501
        except IOError:  # interface is present in routing tables but does not have any assigned IP  # noqa: E501
            ifaddr = "0.0.0.0"
            ifaddr_int = 0
        else:
            addrfamily = struct.unpack("h", ifreq[16:18])[0]
            if addrfamily == socket.AF_INET:
                ifaddr = scapy.utils.inet_ntoa(ifreq[20:24])
                ifaddr_int = struct.unpack("!I", ifreq[20:24])[0]
            else:
                warning("Interface %s: unknown address family (%i)", iff, addrfamily)  # noqa: E501
                continue

        # Attempt to detect an interface alias based on addresses inconsistencies  # noqa: E501
        dst_int = socket.htonl(int(dst, 16)) & 0xffffffff
        msk_int = socket.htonl(int(msk, 16)) & 0xffffffff
        gw_str = scapy.utils.inet_ntoa(struct.pack("I", int(gw, 16)))
        metric = int(metric)

        if ifaddr_int & msk_int != dst_int:
            tmp_route = get_alias_address(iff, dst_int, gw_str, metric)
            if tmp_route:
                routes.append(tmp_route)
            else:
                routes.append((dst_int, msk_int, gw_str, iff, ifaddr, metric))

        else:
            routes.append((dst_int, msk_int, gw_str, iff, ifaddr, metric))

    f.close()
    s.close()
    return routes

############
#   IPv6   #
############


def in6_getifaddr():
    """
    Returns a list of 3-tuples of the form (addr, scope, iface) where
    'addr' is the address of scope 'scope' associated to the interface
    'ifcace'.

    This is the list of all addresses of all interfaces available on
    the system.
    """
    ret = []
    try:
        fdesc = open("/proc/net/if_inet6", "rb")
    except IOError:
        return ret
    for line in fdesc:
        # addr, index, plen, scope, flags, ifname
        tmp = plain_str(line).split()
        addr = scapy.utils6.in6_ptop(
            b':'.join(
                struct.unpack('4s4s4s4s4s4s4s4s', tmp[0].encode())
            ).decode()
        )
        # (addr, scope, iface)
        ret.append((addr, int(tmp[3], 16), tmp[5]))
    fdesc.close()
    return ret


def read_routes6():
    try:
        f = open("/proc/net/ipv6_route", "rb")
    except IOError:
        return []
    # 1. destination network
    # 2. destination prefix length
    # 3. source network displayed
    # 4. source prefix length
    # 5. next hop
    # 6. metric
    # 7. reference counter (?!?)
    # 8. use counter (?!?)
    # 9. flags
    # 10. device name
    routes = []

    def proc2r(p):
        ret = struct.unpack('4s4s4s4s4s4s4s4s', raw(p))
        ret = b':'.join(ret).decode()
        return scapy.utils6.in6_ptop(ret)

    lifaddr = in6_getifaddr()
    for line in f.readlines():
        line = plain_str(line)
        d, dp, s, sp, nh, metric, rc, us, fl, dev = line.split()
        metric = int(metric, 16)
        fl = int(fl, 16)

        if fl & RTF_UP == 0:
            continue
        if fl & RTF_REJECT:
            continue

        d = proc2r(d)
        dp = int(dp, 16)
        s = proc2r(s)
        sp = int(sp, 16)
        nh = proc2r(nh)

        cset = []  # candidate set (possible source addresses)
        if dev == LOOPBACK_NAME:
            if d == '::':
                continue
            cset = ['::1']
        else:
            devaddrs = (x for x in lifaddr if x[2] == dev)
            cset = scapy.utils6.construct_source_candidate_set(d, dp, devaddrs)

        if len(cset) != 0:
            routes.append((d, dp, nh, dev, cset, metric))
    f.close()
    return routes


def get_if_index(iff):
    return int(struct.unpack("I", get_if(iff, SIOCGIFINDEX)[16:20])[0])


if os.uname()[4] in ['x86_64', 'aarch64']:
    def get_last_packet_timestamp(sock):
        ts = ioctl(sock, SIOCGSTAMP, "1234567890123456")
        s, us = struct.unpack("QQ", ts)
        return s + us / 1000000.0
else:
    def get_last_packet_timestamp(sock):
        ts = ioctl(sock, SIOCGSTAMP, "12345678")
        s, us = struct.unpack("II", ts)
        return s + us / 1000000.0


def _flush_fd(fd):
    if hasattr(fd, 'fileno'):
        fd = fd.fileno()
    while True:
        r, w, e = select([fd], [], [], 0)
        if r:
            os.read(fd, MTU)
        else:
            break


def get_iface_mode(iface):
    """Return the interface mode.
    params:
     - iface: the iwconfig interface
    """
    p = subprocess.Popen(["iwconfig", iface], stdout=subprocess.PIPE,
                         stderr=subprocess.STDOUT)
    output, err = p.communicate()
    match = re.search(br"mode:([a-zA-Z]*)", output.lower())
    if match:
        return plain_str(match.group(1))
    return "unknown"


def set_iface_monitor(iface, monitor):
    """Sets the monitor mode (or remove it) from an interface.
    params:
     - iface: the iwconfig interface
     - monitor: True if the interface should be set in monitor mode,
                False if it should be in managed mode
    """
    mode = get_iface_mode(iface)
    if mode == "unknown":
        warning("Could not parse iwconfig !")
    current_monitor = mode == "monitor"
    if monitor == current_monitor:
        # Already correct
        return True
    s_mode = "monitor" if monitor else "managed"

    def _check_call(commands):
        p = subprocess.Popen(commands,
                             stderr=subprocess.PIPE,
                             stdout=subprocess.PIPE)
        stdout, stderr = p.communicate()
        if p.returncode != 0:
            warning("%s failed !" % " ".join(commands))
            return False
        return True
    try:
        assert _check_call(["ifconfig", iface, "down"])
        assert _check_call(["iwconfig", iface, "mode", s_mode])
        assert _check_call(["ifconfig", iface, "up"])
        return True
    except AssertionError:
        return False


class L2Socket(SuperSocket):
    desc = "read/write packets at layer 2 using Linux PF_PACKET sockets"

    def __init__(self, iface=None, type=ETH_P_ALL, promisc=None, filter=None,
                 nofilter=0, monitor=None):
        self.iface = conf.iface if iface is None else iface
        self.type = type
        self.promisc = conf.sniff_promisc if promisc is None else promisc
        if monitor is not None:
            if not set_iface_monitor(iface, monitor):
                warning("Could not change interface mode !")
        self.ins = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, socket.htons(type))  # noqa: E501
        self.ins.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 0)
        if not nofilter:
            if conf.except_filter:
                if filter:
                    filter = "(%s) and not (%s)" % (filter, conf.except_filter)
                else:
                    filter = "not (%s)" % conf.except_filter
            if filter is not None:
                attach_filter(self.ins, filter, iface)
        if self.promisc:
            set_promisc(self.ins, self.iface)
        self.ins.bind((self.iface, type))
        _flush_fd(self.ins)
        self.ins.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 2**30)
        if isinstance(self, L2ListenSocket):
            self.outs = None
        else:
            self.outs = self.ins
            self.outs.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 2**30)
        sa_ll = self.ins.getsockname()
        if sa_ll[3] in conf.l2types:
            self.LL = conf.l2types[sa_ll[3]]
            self.lvl = 2
        elif sa_ll[1] in conf.l3types:
            self.LL = conf.l3types[sa_ll[1]]
            self.lvl = 3
        else:
            self.LL = conf.default_l2
            self.lvl = 2
            warning("Unable to guess type (interface=%s protocol=%#x family=%i). Using %s", sa_ll[0], sa_ll[1], sa_ll[3], self.LL.name)  # noqa: E501

    def close(self):
        if self.closed:
            return
        if self.promisc:
            set_promisc(self.ins, self.iface, 0)
        SuperSocket.close(self)

    def recv_raw(self, x=MTU):
        """Receives a packet, then returns a tuple containing (cls, pkt_data, time)"""  # noqa: E501
        pkt, sa_ll = self.ins.recvfrom(x)
        if self.outs and sa_ll[2] == socket.PACKET_OUTGOING:
            return None, None, None
        ts = get_last_packet_timestamp(self.ins)
        return self.LL, pkt, ts

    def send(self, x):
        try:
            return SuperSocket.send(self, x)
        except socket.error as msg:
            if msg.errno == 22 and len(x) < conf.min_pkt_size:
                padding = b"\x00" * (conf.min_pkt_size - len(x))
                if isinstance(x, Packet):
                    return SuperSocket.send(self, x / Padding(load=padding))
                else:
                    return SuperSocket.send(self, raw(x) + padding)
            raise


class L2ListenSocket(L2Socket):
    desc = "read packets at layer 2 using Linux PF_PACKET sockets. Also receives the packets going OUT"  # noqa: E501

    def send(self, x):
        raise Scapy_Exception("Can't send anything with L2ListenSocket")


class L3PacketSocket(L2Socket):
    desc = "read/write packets at layer 3 using Linux PF_PACKET sockets"

    def recv(self, x=MTU):
        pkt = SuperSocket.recv(self, x)
        if pkt and self.lvl == 2:
            pkt = pkt.payload
        return pkt

    def send(self, x):
        iff, a, gw = x.route()
        if iff is None:
            iff = conf.iface
        sdto = (iff, self.type)
        self.outs.bind(sdto)
        sn = self.outs.getsockname()
        ll = lambda x: x
        if type(x) in conf.l3types:
            sdto = (iff, conf.l3types[type(x)])
        if sn[3] in conf.l2types:
            ll = lambda x: conf.l2types[sn[3]]() / x
        sx = raw(ll(x))
        x.sent_time = time.time()
        try:
            self.outs.sendto(sx, sdto)
        except socket.error as msg:
            if msg.errno == 22 and len(sx) < conf.min_pkt_size:
                self.outs.send(sx + b"\x00" * (conf.min_pkt_size - len(sx)))
            elif conf.auto_fragment and msg.errno == 90:
                for p in x.fragment():
                    self.outs.sendto(raw(ll(p)), sdto)
            else:
                raise


class VEthPair(object):
    """
    encapsulates a virtual Ethernet interface pair
    """

    def __init__(self, iface_name, peer_name):

        if not LINUX:
            # ToDo: do we need a kernel version check here?
            raise ScapyInvalidPlatformException(
                'Virtual Ethernet interface pair only available on Linux'
            )

        self.ifaces = [iface_name, peer_name]

    def iface(self):
        return self.ifaces[0]

    def peer(self):
        return self.ifaces[1]

    def setup(self):
        """
        create veth pair links
        :raises subprocess.CalledProcessError if operation fails
        """
        subprocess.check_call(['ip', 'link', 'add', self.ifaces[0], 'type', 'veth', 'peer', 'name', self.ifaces[1]])  # noqa: E501

    def destroy(self):
        """
        remove veth pair links
        :raises subprocess.CalledProcessError if operation failes
        """
        subprocess.check_call(['ip', 'link', 'del', self.ifaces[0]])

    def up(self):
        """
        set veth pair links up
        :raises subprocess.CalledProcessError if operation failes
        """
        for idx in [0, 1]:
            subprocess.check_call(["ip", "link", "set", self.ifaces[idx], "up"])  # noqa: E501

    def down(self):
        """
        set veth pair links down
        :raises subprocess.CalledProcessError if operation failes
        """
        for idx in [0, 1]:
            subprocess.check_call(["ip", "link", "set", self.ifaces[idx], "down"])  # noqa: E501

    def __enter__(self):
        self.setup()
        self.up()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.destroy()
