# 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

"""
Implementation of the configuration object.
"""

from __future__ import absolute_import
from __future__ import print_function
import functools
import os
import re
import time
import socket
import sys

from scapy import VERSION, base_classes
from scapy.consts import DARWIN, WINDOWS, LINUX, BSD, SOLARIS
from scapy.error import log_scapy, warning, ScapyInvalidPlatformException
from scapy.modules import six
from scapy.themes import NoTheme, apply_ipython_style

############
#  Config  #
############


class ConfClass(object):
    def configure(self, cnf):
        self.__dict__ = cnf.__dict__.copy()

    def __repr__(self):
        return str(self)

    def __str__(self):
        s = ""
        keys = self.__class__.__dict__.copy()
        keys.update(self.__dict__)
        keys = sorted(keys)
        for i in keys:
            if i[0] != "_":
                r = repr(getattr(self, i))
                r = " ".join(r.split())
                wlen = 76 - max(len(i), 10)
                if len(r) > wlen:
                    r = r[:wlen - 3] + "..."
                s += "%-10s = %s\n" % (i, r)
        return s[:-1]


class Interceptor(object):
    def __init__(self, name=None, default=None,
                 hook=None, args=None, kargs=None):
        self.name = name
        self.intname = "_intercepted_%s" % name
        self.default = default
        self.hook = hook
        self.args = args if args is not None else []
        self.kargs = kargs if kargs is not None else {}

    def __get__(self, obj, typ=None):
        if not hasattr(obj, self.intname):
            setattr(obj, self.intname, self.default)
        return getattr(obj, self.intname)

    @staticmethod
    def set_from_hook(obj, name, val):
        int_name = "_intercepted_%s" % name
        setattr(obj, int_name, val)

    def __set__(self, obj, val):
        setattr(obj, self.intname, val)
        self.hook(self.name, val, *self.args, **self.kargs)


def _readonly(name):
    default = Conf.__dict__[name].default
    Interceptor.set_from_hook(conf, name, default)
    raise ValueError("Read-only value !")


ReadOnlyAttribute = functools.partial(
    Interceptor,
    hook=(lambda name, *args, **kwargs: _readonly(name))
)
ReadOnlyAttribute.__doc__ = "Read-only class attribute"


class ProgPath(ConfClass):
    universal_open = "open" if DARWIN else "xdg-open"
    pdfreader = universal_open
    psreader = universal_open
    svgreader = universal_open
    dot = "dot"
    display = "display"
    tcpdump = "tcpdump"
    tcpreplay = "tcpreplay"
    hexedit = "hexer"
    tshark = "tshark"
    wireshark = "wireshark"
    ifconfig = "ifconfig"


class ConfigFieldList:
    def __init__(self):
        self.fields = set()
        self.layers = set()

    @staticmethod
    def _is_field(f):
        return hasattr(f, "owners")

    def _recalc_layer_list(self):
        self.layers = {owner for f in self.fields for owner in f.owners}

    def add(self, *flds):
        self.fields |= {f for f in flds if self._is_field(f)}
        self._recalc_layer_list()

    def remove(self, *flds):
        self.fields -= set(flds)
        self._recalc_layer_list()

    def __contains__(self, elt):
        if isinstance(elt, base_classes.Packet_metaclass):
            return elt in self.layers
        return elt in self.fields

    def __repr__(self):
        return "<%s [%s]>" % (self.__class__.__name__, " ".join(str(x) for x in self.fields))  # noqa: E501


class Emphasize(ConfigFieldList):
    pass


class Resolve(ConfigFieldList):
    pass


class Num2Layer:
    def __init__(self):
        self.num2layer = {}
        self.layer2num = {}

    def register(self, num, layer):
        self.register_num2layer(num, layer)
        self.register_layer2num(num, layer)

    def register_num2layer(self, num, layer):
        self.num2layer[num] = layer

    def register_layer2num(self, num, layer):
        self.layer2num[layer] = num

    def __getitem__(self, item):
        if isinstance(item, base_classes.Packet_metaclass):
            return self.layer2num[item]
        return self.num2layer[item]

    def __contains__(self, item):
        if isinstance(item, base_classes.Packet_metaclass):
            return item in self.layer2num
        return item in self.num2layer

    def get(self, item, default=None):
        return self[item] if item in self else default

    def __repr__(self):
        lst = []
        for num, layer in six.iteritems(self.num2layer):
            if layer in self.layer2num and self.layer2num[layer] == num:
                dir = "<->"
            else:
                dir = " ->"
            lst.append((num, "%#6x %s %-20s (%s)" % (num, dir, layer.__name__,
                                                     layer._name)))
        for layer, num in six.iteritems(self.layer2num):
            if num not in self.num2layer or self.num2layer[num] != layer:
                lst.append((num, "%#6x <-  %-20s (%s)" % (num, layer.__name__,
                                                          layer._name)))
        lst.sort()
        return "\n".join(y for x, y in lst)


class LayersList(list):

    def __init__(self):
        list.__init__(self)
        self.ldict = {}

    def __repr__(self):
        return "\n".join("%-20s: %s" % (l.__name__, l.name) for l in self)

    def register(self, layer):
        self.append(layer)
        if layer.__module__ not in self.ldict:
            self.ldict[layer.__module__] = []
        self.ldict[layer.__module__].append(layer)

    def layers(self):
        result = []
        # This import may feel useless, but it is required for the eval below
        import scapy  # noqa: F401
        for lay in self.ldict:
            doc = eval(lay).__doc__
            result.append((lay, doc.strip().split("\n")[0] if doc else lay))
        return result


class CommandsList(list):
    def __repr__(self):
        s = []
        for l in sorted(self, key=lambda x: x.__name__):
            doc = l.__doc__.split("\n")[0] if l.__doc__ else "--"
            s.append("%-20s: %s" % (l.__name__, doc))
        return "\n".join(s)

    def register(self, cmd):
        self.append(cmd)
        return cmd  # return cmd so that method can be used as a decorator


def lsc():
    """Displays Scapy's default commands"""
    print(repr(conf.commands))


class CacheInstance(dict, object):
    __slots__ = ["timeout", "name", "_timetable", "__dict__"]

    def __init__(self, name="noname", timeout=None):
        self.timeout = timeout
        self.name = name
        self._timetable = {}

    def flush(self):
        self.__init__(name=self.name, timeout=self.timeout)

    def __getitem__(self, item):
        if item in self.__slots__:
            return object.__getattribute__(self, item)
        val = dict.__getitem__(self, item)
        if self.timeout is not None:
            t = self._timetable[item]
            if time.time() - t > self.timeout:
                raise KeyError(item)
        return val

    def get(self, item, default=None):
        # overloading this method is needed to force the dict to go through
        # the timetable check
        try:
            return self[item]
        except KeyError:
            return default

    def __setitem__(self, item, v):
        if item in self.__slots__:
            return object.__setattr__(self, item, v)
        self._timetable[item] = time.time()
        dict.__setitem__(self, item, v)

    def update(self, other):
        for key, value in six.iteritems(other):
            # We only update an element from `other` either if it does
            # not exist in `self` or if the entry in `self` is older.
            if key not in self or self._timetable[key] < other._timetable[key]:
                dict.__setitem__(self, key, value)
                self._timetable[key] = other._timetable[key]

    def iteritems(self):
        if self.timeout is None:
            return six.iteritems(self.__dict__)
        t0 = time.time()
        return ((k, v) for (k, v) in six.iteritems(self.__dict__) if t0 - self._timetable[k] < self.timeout)  # noqa: E501

    def iterkeys(self):
        if self.timeout is None:
            return six.iterkeys(self.__dict__)
        t0 = time.time()
        return (k for k in six.iterkeys(self.__dict__) if t0 - self._timetable[k] < self.timeout)  # noqa: E501

    def __iter__(self):
        return six.iterkeys(self.__dict__)

    def itervalues(self):
        if self.timeout is None:
            return six.itervalues(self.__dict__)
        t0 = time.time()
        return (v for (k, v) in six.iteritems(self.__dict__) if t0 - self._timetable[k] < self.timeout)  # noqa: E501

    def items(self):
        if self.timeout is None:
            return dict.items(self)
        t0 = time.time()
        return [(k, v) for (k, v) in six.iteritems(self.__dict__) if t0 - self._timetable[k] < self.timeout]  # noqa: E501

    def keys(self):
        if self.timeout is None:
            return dict.keys(self)
        t0 = time.time()
        return [k for k in six.iterkeys(self.__dict__) if t0 - self._timetable[k] < self.timeout]  # noqa: E501

    def values(self):
        if self.timeout is None:
            return list(six.itervalues(self))
        t0 = time.time()
        return [v for (k, v) in six.iteritems(self.__dict__) if t0 - self._timetable[k] < self.timeout]  # noqa: E501

    def __len__(self):
        if self.timeout is None:
            return dict.__len__(self)
        return len(self.keys())

    def summary(self):
        return "%s: %i valid items. Timeout=%rs" % (self.name, len(self), self.timeout)  # noqa: E501

    def __repr__(self):
        s = []
        if self:
            mk = max(len(k) for k in six.iterkeys(self.__dict__))
            fmt = "%%-%is %%s" % (mk + 1)
            for item in six.iteritems(self.__dict__):
                s.append(fmt % item)
        return "\n".join(s)


class NetCache:
    def __init__(self):
        self._caches_list = []

    def add_cache(self, cache):
        self._caches_list.append(cache)
        setattr(self, cache.name, cache)

    def new_cache(self, name, timeout=None):
        c = CacheInstance(name=name, timeout=timeout)
        self.add_cache(c)

    def __delattr__(self, attr):
        raise AttributeError("Cannot delete attributes")

    def update(self, other):
        for co in other._caches_list:
            if hasattr(self, co.name):
                getattr(self, co.name).update(co)
            else:
                self.add_cache(co.copy())

    def flush(self):
        for c in self._caches_list:
            c.flush()

    def __repr__(self):
        return "\n".join(c.summary() for c in self._caches_list)


def _version_checker(module, minver):
    """Checks that module has a higher version that minver.

    params:
     - module: a module to test
     - minver: a tuple of versions
    """
    # We could use LooseVersion, but distutils imports imp which is deprecated
    version_regexp = r'[a-z]?((?:\d|\.)+\d+)(?:\.dev[0-9]+)?'
    version_tags = re.match(version_regexp, module.__version__)
    if not version_tags:
        return False
    version_tags = version_tags.group(1).split(".")
    version_tags = tuple(int(x) for x in version_tags)
    return version_tags >= minver


def isCryptographyValid():
    """
    Check if the cryptography library is present, and if it is recent enough
    for most usages in scapy (v1.7 or later).
    """
    try:
        import cryptography
    except ImportError:
        return False
    return _version_checker(cryptography, (1, 7))


def isCryptographyAdvanced():
    """
    Check if the cryptography library is present, and if it supports X25519,
    ChaCha20Poly1305 and such (v2.0 or later).
    """
    try:
        from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey  # noqa: E501
        X25519PrivateKey.generate()
    except Exception:
        return False
    else:
        return True


def isPyPy():
    """Returns either scapy is running under PyPy or not"""
    try:
        import __pypy__  # noqa: F401
        return True
    except ImportError:
        return False


def _prompt_changer(attr, val):
    """Change the current prompt theme"""
    try:
        sys.ps1 = conf.color_theme.prompt(conf.prompt)
    except Exception:
        pass
    try:
        apply_ipython_style(get_ipython())
    except NameError:
        pass


def _set_conf_sockets():
    """Populate the conf.L2Socket and conf.L3Socket
    according to the various use_* parameters
    """
    from scapy.main import _load
    if conf.use_bpf and not BSD:
        Interceptor.set_from_hook(conf, "use_bpf", False)
        raise ScapyInvalidPlatformException("BSD-like (OSX, *BSD...) only !")
    if not conf.use_pcap and SOLARIS:
        Interceptor.set_from_hook(conf, "use_pcap", True)
        raise ScapyInvalidPlatformException(
            "Scapy only supports libpcap on Solaris !"
        )
    # we are already in an Interceptor hook, use Interceptor.set_from_hook
    if conf.use_pcap or conf.use_dnet:
        try:
            from scapy.arch.pcapdnet import L2pcapListenSocket, L2pcapSocket, \
                L3pcapSocket
        except (OSError, ImportError):
            warning("No libpcap provider available ! pcap won't be used")
            Interceptor.set_from_hook(conf, "use_pcap", False)
        else:
            conf.L3socket = L3pcapSocket
            conf.L3socket6 = functools.partial(L3pcapSocket, filter="ip6")
            conf.L2socket = L2pcapSocket
            conf.L2listen = L2pcapListenSocket
            # Update globals
            _load("scapy.arch.pcapdnet")
            return
    if conf.use_bpf:
        from scapy.arch.bpf.supersocket import L2bpfListenSocket, \
            L2bpfSocket, L3bpfSocket
        conf.L3socket = L3bpfSocket
        conf.L3socket6 = functools.partial(L3bpfSocket, filter="ip6")
        conf.L2socket = L2bpfSocket
        conf.L2listen = L2bpfListenSocket
        # Update globals
        _load("scapy.arch.bpf")
        return
    if LINUX:
        from scapy.arch.linux import L3PacketSocket, L2Socket, L2ListenSocket
        conf.L3socket = L3PacketSocket
        conf.L3socket6 = functools.partial(L3PacketSocket, filter="ip6")
        conf.L2socket = L2Socket
        conf.L2listen = L2ListenSocket
        # Update globals
        _load("scapy.arch.linux")
        return
    if WINDOWS:
        from scapy.arch.windows import _NotAvailableSocket
        from scapy.arch.windows.native import L3WinSocket, L3WinSocket6
        conf.L3socket = L3WinSocket
        conf.L3socket6 = L3WinSocket6
        conf.L2socket = _NotAvailableSocket
        conf.L2listen = _NotAvailableSocket
        # No need to update globals on Windows
        return
    from scapy.supersocket import L3RawSocket
    from scapy.layers.inet6 import L3RawSocket6
    conf.L3socket = L3RawSocket
    conf.L3socket6 = L3RawSocket6


def _socket_changer(attr, val):
    if not isinstance(val, bool):
        raise TypeError("This argument should be a boolean")
    dependencies = {  # Things that will be turned off
        "use_pcap": ["use_bpf"],
        "use_bpf": ["use_pcap"],
    }
    restore = {k: getattr(conf, k) for k in dependencies}
    del restore[attr]  # This is handled directly by _set_conf_sockets
    if val:  # Only if True
        for param in dependencies[attr]:
            Interceptor.set_from_hook(conf, param, False)
    try:
        _set_conf_sockets()
    except (ScapyInvalidPlatformException, ImportError) as e:
        for key, value in restore.items():
            Interceptor.set_from_hook(conf, key, value)
        if isinstance(e, ScapyInvalidPlatformException):
            raise


def _loglevel_changer(attr, val):
    """Handle a change of conf.logLevel"""
    log_scapy.setLevel(val)


class Conf(ConfClass):
    """
    This object contains the configuration of Scapy.

    Attributes:
        session: filename where the session will be saved
        interactive_shell : can be "ipython", "python" or "auto". Default: Auto
        stealth: if 1, prevents any unwanted packet to go out (ARP, DNS, ...)
        checkIPID: if 0, doesn't check that IPID matches between IP sent and
            ICMP IP citation received
            if 1, checks that they either are equal or byte swapped
            equals (bug in some IP stacks)
            if 2, strictly checks that they are equals
        checkIPsrc: if 1, checks IP src in IP and ICMP IP citation match
            (bug in some NAT stacks)
        checkIPinIP: if True, checks that IP-in-IP layers match. If False, do
            not check IP layers that encapsulates another IP layer
        check_TCPerror_seqack: if 1, also check that TCP seq and ack match the
            ones in ICMP citation
        iff: selects the default output interface for srp() and sendp().
        verb: level of verbosity, from 0 (almost mute) to 3 (verbose)
        promisc: default mode for listening socket (to get answers if you
            spoof on a lan)
        sniff_promisc: default mode for sniff()
        filter: bpf filter added to every sniffing socket to exclude traffic
            from analysis
        histfile: history file
        padding: includes padding in disassembled packets
        except_filter : BPF filter for packets to ignore
        debug_match: when 1, store received packet that are not matched into
            `debug.recv`
        route: holds the Scapy routing table and provides methods to
            manipulate it
        warning_threshold : how much time between warnings from the same place
        ASN1_default_codec: Codec used by default for ASN1 objects
        mib: holds MIB direct access dictionary
        resolve: holds list of fields for which resolution should be done
        noenum: holds list of enum fields for which conversion to string
            should NOT be done
        AS_resolver: choose the AS resolver class to use
        extensions_paths: path or list of paths where extensions are to be
                           looked for
        contribs: a dict which can be used by contrib layers to store local
            configuration
        debug_tls: When 1, print some TLS session secrets
            when they are computed.
        recv_poll_rate: how often to check for new packets. Defaults to 0.05s.
        raise_no_dst_mac: When True, raise exception if no dst MAC found
            otherwise broadcast. Default is False.
    """
    version = ReadOnlyAttribute("version", VERSION)
    session = ""
    interactive = False
    interactive_shell = ""
    stealth = "not implemented"
    iface = None
    iface6 = None
    layers = LayersList()
    commands = CommandsList()
    dot15d4_protocol = None  # Used in dot15d4.py
    logLevel = Interceptor("logLevel", log_scapy.level, _loglevel_changer)
    checkIPID = False
    checkIPsrc = True
    checkIPaddr = True
    checkIPinIP = True
    check_TCPerror_seqack = False
    verb = 2
    prompt = Interceptor("prompt", ">>> ", _prompt_changer)
    promisc = True
    sniff_promisc = 1
    raw_layer = None
    raw_summary = False
    default_l2 = None
    l2types = Num2Layer()
    l3types = Num2Layer()
    L3socket = None
    L3socket6 = None
    L2socket = None
    L2listen = None
    BTsocket = None
    USBsocket = None
    min_pkt_size = 60
    bufsize = 2**16
    histfile = os.getenv('SCAPY_HISTFILE',
                         os.path.join(os.path.expanduser("~"),
                                      ".scapy_history"))
    padding = 1
    except_filter = ""
    debug_match = False
    debug_tls = False
    wepkey = ""
    cache_iflist = {}
    route = None  # Filed by route.py
    route6 = None  # Filed by route6.py
    auto_fragment = True
    debug_dissector = False
    color_theme = Interceptor("color_theme", NoTheme(), _prompt_changer)
    warning_threshold = 5
    prog = ProgPath()
    resolve = Resolve()
    noenum = Resolve()
    emph = Emphasize()
    use_pypy = ReadOnlyAttribute("use_pypy", isPyPy())
    use_pcap = Interceptor(
        "use_pcap",
        os.getenv("SCAPY_USE_PCAPDNET", "").lower().startswith("y"),
        _socket_changer
    )
    # XXX use_dnet is deprecated
    use_dnet = os.getenv("SCAPY_USE_PCAPDNET", "").lower().startswith("y")
    use_bpf = Interceptor("use_bpf", False, _socket_changer)
    use_npcap = False
    ipv6_enabled = socket.has_ipv6
    extensions_paths = "."
    stats_classic_protocols = []
    stats_dot11_protocols = []
    temp_files = []
    netcache = NetCache()
    geoip_city = None
    # can, tls, http are not loaded by default
    load_layers = ['bluetooth', 'bluetooth4LE', 'dhcp', 'dhcp6', 'dns',
                   'dot11', 'dot15d4', 'eap', 'gprs', 'hsrp', 'inet',
                   'inet6', 'ipsec', 'ir', 'isakmp', 'l2', 'l2tp',
                   'llmnr', 'lltd', 'mgcp', 'mobileip', 'netbios',
                   'netflow', 'ntp', 'ppi', 'ppp', 'pptp', 'radius', 'rip',
                   'rtp', 'sctp', 'sixlowpan', 'skinny', 'smb', 'snmp',
                   'tftp', 'vrrp', 'vxlan', 'x509', 'zigbee']
    contribs = dict()
    crypto_valid = isCryptographyValid()
    crypto_valid_advanced = isCryptographyAdvanced()
    fancy_prompt = True
    auto_crop_tables = True
    recv_poll_rate = 0.05
    raise_no_dst_mac = False

    def __getattr__(self, attr):
        # Those are loaded on runtime to avoid import loops
        if attr == "manufdb":
            from scapy.data import MANUFDB
            return MANUFDB
        if attr == "ethertypes":
            from scapy.data import ETHER_TYPES
            return ETHER_TYPES
        if attr == "protocols":
            from scapy.data import IP_PROTOS
            return IP_PROTOS
        if attr == "services_udp":
            from scapy.data import UDP_SERVICES
            return UDP_SERVICES
        if attr == "services_tcp":
            from scapy.data import TCP_SERVICES
            return TCP_SERVICES
        return object.__getattr__(self, attr)


if not Conf.ipv6_enabled:
    log_scapy.warning("IPv6 support disabled in Python. Cannot load Scapy IPv6 layers.")  # noqa: E501
    for m in ["inet6", "dhcp6"]:
        if m in Conf.load_layers:
            Conf.load_layers.remove(m)

conf = Conf()


def crypto_validator(func):
    """
    This a decorator to be used for any method relying on the cryptography library.  # noqa: E501
    Its behaviour depends on the 'crypto_valid' attribute of the global 'conf'.
    """
    def func_in(*args, **kwargs):
        if not conf.crypto_valid:
            raise ImportError("Cannot execute crypto-related method! "
                              "Please install python-cryptography v1.7 or later.")  # noqa: E501
        return func(*args, **kwargs)
    return func_in
