# 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

"""
Packet class. Binding mechanism. fuzz() method.
"""

from __future__ import absolute_import
from __future__ import print_function
import re
import time
import itertools
import copy
import types

from scapy.fields import StrField, ConditionalField, Emph, PacketListField, \
    BitField, MultiEnumField, EnumField, FlagsField, MultipleTypeField
from scapy.config import conf, _version_checker
from scapy.compat import raw, orb
from scapy.base_classes import BasePacket, Gen, SetGen, Packet_metaclass, \
    _CanvasDumpExtended
from scapy.volatile import VolatileValue, RandField
from scapy.utils import import_hexcap, tex_escape, colgen, issubtype, \
    pretty_list
from scapy.error import Scapy_Exception, log_runtime
from scapy.extlib import PYX
import scapy.modules.six as six

try:
    import pyx
except ImportError:
    pass


class RawVal:
    def __init__(self, val=""):
        self.val = val

    def __str__(self):
        return str(self.val)

    def __bytes__(self):
        return raw(self.val)

    def __repr__(self):
        return "<RawVal [%r]>" % self.val


class Packet(six.with_metaclass(Packet_metaclass, BasePacket,
                                _CanvasDumpExtended)):
    __slots__ = [
        "time", "sent_time", "name", "default_fields",
        "overload_fields", "overloaded_fields", "fields", "fieldtype",
        "packetfields",
        "original", "explicit", "raw_packet_cache",
        "raw_packet_cache_fields", "_pkt", "post_transforms",
        # then payload and underlayer
        "payload", "underlayer",
        "name",
        # used for sr()
        "_answered",
        # used when sniffing
        "direction", "sniffed_on",
        # handle snaplen Vs real length
        "wirelen",
        # used while performing advanced dissection to handle padding
        "_tmp_dissect_pos",
    ]
    name = None
    fields_desc = []
    overload_fields = {}
    payload_guess = []
    show_indent = 1
    show_summary = True
    class_dont_cache = dict()
    class_packetfields = dict()
    class_default_fields = dict()
    class_default_fields_ref = dict()
    class_fieldtype = dict()

    @classmethod
    def from_hexcap(cls):
        return cls(import_hexcap())

    @classmethod
    def upper_bonds(self):
        for fval, upper in self.payload_guess:
            print("%-20s  %s" % (upper.__name__, ", ".join("%-12s" % ("%s=%r" % i) for i in six.iteritems(fval))))  # noqa: E501

    @classmethod
    def lower_bonds(self):
        for lower, fval in six.iteritems(self._overload_fields):
            print("%-20s  %s" % (lower.__name__, ", ".join("%-12s" % ("%s=%r" % i) for i in six.iteritems(fval))))  # noqa: E501

    def _unpickle(self, dlist):
        """Used to unpack pickling"""
        self.__init__(b"".join(dlist))
        return self

    def __reduce__(self):
        """Used by pickling methods"""
        return (self.__class__, (), (self.build(),))

    def __reduce_ex__(self, proto):
        """Used by pickling methods"""
        return self.__reduce__()

    def __getstate__(self):
        """Mark object as pickable"""
        return self.__reduce__()[2]

    def __setstate__(self, state):
        """Rebuild state using pickable methods"""
        return self._unpickle(state)

    def __deepcopy__(self, memo):
        """Used by copy.deepcopy"""
        return self.copy()

    def __init__(self, _pkt=b"", post_transform=None, _internal=0, _underlayer=None, **fields):  # noqa: E501
        self.time = time.time()
        self.sent_time = None
        self.name = (self.__class__.__name__
                     if self._name is None else
                     self._name)
        self.default_fields = {}
        self.overload_fields = self._overload_fields
        self.overloaded_fields = {}
        self.fields = {}
        self.fieldtype = {}
        self.packetfields = []
        self.payload = NoPayload()
        self.init_fields()
        self.underlayer = _underlayer
        self.original = _pkt
        self.explicit = 0
        self.raw_packet_cache = None
        self.raw_packet_cache_fields = None
        self.wirelen = None
        if _pkt:
            self.dissect(_pkt)
            if not _internal:
                self.dissection_done(self)
        # We use this strange initialization so that the fields
        # are initialized in their declaration order.
        # It is required to always support MultipleTypeField
        for field in self.fields_desc:
            fname = field.name
            try:
                value = fields.pop(fname)
            except KeyError:
                continue
            self.fields[fname] = self.get_field(fname).any2i(self, value)
        # The remaining fields are unknown
        for fname, _ in fields:
            raise AttributeError(fname)
        if isinstance(post_transform, list):
            self.post_transforms = post_transform
        elif post_transform is None:
            self.post_transforms = []
        else:
            self.post_transforms = [post_transform]

    def init_fields(self):
        """
        Initialize each fields of the fields_desc dict
        """

        if self.class_dont_cache.get(self.__class__, False):
            self.do_init_fields(self.fields_desc)
        else:
            self.do_init_cached_fields()

    def do_init_fields(self, flist):
        """
        Initialize each fields of the fields_desc dict
        """
        for f in flist:
            self.default_fields[f.name] = copy.deepcopy(f.default)
            self.fieldtype[f.name] = f
            if f.holds_packets:
                self.packetfields.append(f)

    def do_init_cached_fields(self):
        """
        Initialize each fields of the fields_desc dict, or use the cached
        fields information
        """

        cls_name = self.__class__

        # Build the fields information
        if Packet.class_default_fields.get(cls_name, None) is None:
            self.prepare_cached_fields(self.fields_desc)

        # Use fields information from cache
        if not Packet.class_default_fields.get(cls_name, None) is None:
            self.default_fields = Packet.class_default_fields[cls_name]
            self.fieldtype = Packet.class_fieldtype[cls_name]
            self.packetfields = Packet.class_packetfields[cls_name]

            # Deepcopy default references
            for fname in Packet.class_default_fields_ref[cls_name]:
                value = copy.deepcopy(self.default_fields[fname])
                setattr(self, fname, value)

    def prepare_cached_fields(self, flist):
        """
        Prepare the cached fields of the fields_desc dict
        """

        cls_name = self.__class__

        # Fields cache initialization
        if flist:
            Packet.class_default_fields[cls_name] = dict()
            Packet.class_default_fields_ref[cls_name] = list()
            Packet.class_fieldtype[cls_name] = dict()
            Packet.class_packetfields[cls_name] = list()

        # Fields initialization
        for f in flist:
            if isinstance(f, MultipleTypeField):
                del Packet.class_default_fields[cls_name]
                del Packet.class_default_fields_ref[cls_name]
                del Packet.class_fieldtype[cls_name]
                del Packet.class_packetfields[cls_name]
                self.class_dont_cache[cls_name] = True
                self.do_init_fields(self.fields_desc)
                break

            tmp_copy = copy.deepcopy(f.default)
            Packet.class_default_fields[cls_name][f.name] = tmp_copy
            Packet.class_fieldtype[cls_name][f.name] = f
            if f.holds_packets:
                Packet.class_packetfields[cls_name].append(f)

            # Remember references
            if isinstance(f.default, (list, dict, set, RandField, Packet)):
                Packet.class_default_fields_ref[cls_name].append(f.name)

    def dissection_done(self, pkt):
        """DEV: will be called after a dissection is completed"""
        self.post_dissection(pkt)
        self.payload.dissection_done(pkt)

    def post_dissection(self, pkt):
        """DEV: is called after the dissection of the whole packet"""
        pass

    def get_field(self, fld):
        """DEV: returns the field instance from the name of the field"""
        return self.fieldtype[fld]

    def add_payload(self, payload):
        if payload is None:
            return
        elif not isinstance(self.payload, NoPayload):
            self.payload.add_payload(payload)
        else:
            if isinstance(payload, Packet):
                self.payload = payload
                payload.add_underlayer(self)
                for t in self.aliastypes:
                    if t in payload.overload_fields:
                        self.overloaded_fields = payload.overload_fields[t]
                        break
            elif isinstance(payload, bytes):
                self.payload = conf.raw_layer(load=payload)
            else:
                raise TypeError("payload must be either 'Packet' or 'bytes', not [%s]" % repr(payload))  # noqa: E501

    def remove_payload(self):
        self.payload.remove_underlayer(self)
        self.payload = NoPayload()
        self.overloaded_fields = {}

    def add_underlayer(self, underlayer):
        self.underlayer = underlayer

    def remove_underlayer(self, other):
        self.underlayer = None

    def copy(self):
        """Returns a deep copy of the instance."""
        clone = self.__class__()
        clone.fields = self.copy_fields_dict(self.fields)
        clone.default_fields = self.copy_fields_dict(self.default_fields)
        clone.overloaded_fields = self.overloaded_fields.copy()
        clone.underlayer = self.underlayer
        clone.explicit = self.explicit
        clone.raw_packet_cache = self.raw_packet_cache
        clone.raw_packet_cache_fields = self.copy_fields_dict(
            self.raw_packet_cache_fields
        )
        clone.wirelen = self.wirelen
        clone.post_transforms = self.post_transforms[:]
        clone.payload = self.payload.copy()
        clone.payload.add_underlayer(clone)
        clone.time = self.time
        return clone

    def getfieldval(self, attr):
        if attr in self.fields:
            return self.fields[attr]
        if attr in self.overloaded_fields:
            return self.overloaded_fields[attr]
        if attr in self.default_fields:
            return self.default_fields[attr]
        return self.payload.getfieldval(attr)

    def getfield_and_val(self, attr):
        if attr in self.fields:
            return self.get_field(attr), self.fields[attr]
        if attr in self.overloaded_fields:
            return self.get_field(attr), self.overloaded_fields[attr]
        if attr in self.default_fields:
            return self.get_field(attr), self.default_fields[attr]

    def __getattr__(self, attr):
        try:
            fld, v = self.getfield_and_val(attr)
        except TypeError:
            return self.payload.__getattr__(attr)
        if fld is not None:
            return fld.i2h(self, v)
        return v

    def setfieldval(self, attr, val):
        if attr in self.default_fields:
            fld = self.get_field(attr)
            if fld is None:
                any2i = lambda x, y: y
            else:
                any2i = fld.any2i
            self.fields[attr] = any2i(self, val)
            self.explicit = 0
            self.raw_packet_cache = None
            self.raw_packet_cache_fields = None
            self.wirelen = None
        elif attr == "payload":
            self.remove_payload()
            self.add_payload(val)
        else:
            self.payload.setfieldval(attr, val)

    def __setattr__(self, attr, val):
        if attr in self.__all_slots__:
            return object.__setattr__(self, attr, val)
        try:
            return self.setfieldval(attr, val)
        except AttributeError:
            pass
        return object.__setattr__(self, attr, val)

    def delfieldval(self, attr):
        if attr in self.fields:
            del(self.fields[attr])
            self.explicit = 0  # in case a default value must be explicit
            self.raw_packet_cache = None
            self.raw_packet_cache_fields = None
            self.wirelen = None
        elif attr in self.default_fields:
            pass
        elif attr == "payload":
            self.remove_payload()
        else:
            self.payload.delfieldval(attr)

    def __delattr__(self, attr):
        if attr == "payload":
            return self.remove_payload()
        if attr in self.__all_slots__:
            return object.__delattr__(self, attr)
        try:
            return self.delfieldval(attr)
        except AttributeError:
            pass
        return object.__delattr__(self, attr)

    def _superdir(self):
        """
        Return a list of slots and methods, including those from subclasses.
        """
        attrs = set()
        cls = self.__class__
        if hasattr(cls, '__all_slots__'):
            attrs.update(cls.__all_slots__)
        for bcls in cls.__mro__:
            if hasattr(bcls, '__dict__'):
                attrs.update(bcls.__dict__)
        return attrs

    def __dir__(self):
        """
        Add fields to tab completion list.
        """
        return sorted(itertools.chain(self._superdir(), self.default_fields))

    def __repr__(self):
        s = ""
        ct = conf.color_theme
        for f in self.fields_desc:
            if isinstance(f, ConditionalField) and not f._evalcond(self):
                continue
            if f.name in self.fields:
                fval = self.fields[f.name]
                if isinstance(fval, (list, dict, set)) and len(fval) == 0:
                    continue
                val = f.i2repr(self, fval)
            elif f.name in self.overloaded_fields:
                fover = self.overloaded_fields[f.name]
                if isinstance(fover, (list, dict, set)) and len(fover) == 0:
                    continue
                val = f.i2repr(self, fover)
            else:
                continue
            if isinstance(f, Emph) or f in conf.emph:
                ncol = ct.emph_field_name
                vcol = ct.emph_field_value
            else:
                ncol = ct.field_name
                vcol = ct.field_value

            s += " %s%s%s" % (ncol(f.name),
                              ct.punct("="),
                              vcol(val))
        return "%s%s %s %s%s%s" % (ct.punct("<"),
                                   ct.layer_name(self.__class__.__name__),
                                   s,
                                   ct.punct("|"),
                                   repr(self.payload),
                                   ct.punct(">"))

    def __str__(self):
        return str(self.build())

    def __bytes__(self):
        return self.build()

    def __div__(self, other):
        if isinstance(other, Packet):
            cloneA = self.copy()
            cloneB = other.copy()
            cloneA.add_payload(cloneB)
            return cloneA
        elif isinstance(other, (bytes, str)):
            return self / conf.raw_layer(load=other)
        else:
            return other.__rdiv__(self)
    __truediv__ = __div__

    def __rdiv__(self, other):
        if isinstance(other, (bytes, str)):
            return conf.raw_layer(load=other) / self
        else:
            raise TypeError
    __rtruediv__ = __rdiv__

    def __mul__(self, other):
        if isinstance(other, int):
            return [self] * other
        else:
            raise TypeError

    def __rmul__(self, other):
        return self.__mul__(other)

    def __nonzero__(self):
        return True
    __bool__ = __nonzero__

    def __len__(self):
        return len(self.__bytes__())

    def copy_field_value(self, fieldname, value):
        return self.get_field(fieldname).do_copy(value)

    def copy_fields_dict(self, fields):
        if fields is None:
            return None
        return {fname: self.copy_field_value(fname, fval)
                for fname, fval in six.iteritems(fields)}

    def clear_cache(self):
        """Clear the raw packet cache for the field and all its subfields"""
        self.raw_packet_cache = None
        for _, fval in six.iteritems(self.fields):
            if isinstance(fval, Packet):
                fval.clear_cache()
        self.payload.clear_cache()

    def self_build(self, field_pos_list=None):
        """
        Create the default layer regarding fields_desc dict

        :param field_pos_list:
        """
        if self.raw_packet_cache is not None:
            for fname, fval in six.iteritems(self.raw_packet_cache_fields):
                if self.getfieldval(fname) != fval:
                    self.raw_packet_cache = None
                    self.raw_packet_cache_fields = None
                    self.wirelen = None
                    break
            if self.raw_packet_cache is not None:
                return self.raw_packet_cache
        p = b""
        for f in self.fields_desc:
            val = self.getfieldval(f.name)
            if isinstance(val, RawVal):
                sval = raw(val)
                p += sval
                if field_pos_list is not None:
                    field_pos_list.append((f.name, sval.encode("string_escape"), len(p), len(sval)))  # noqa: E501
            else:
                p = f.addfield(self, p, val)
        return p

    def do_build_payload(self):
        """
        Create the default version of the payload layer

        :return: a string of payload layer
        """
        return self.payload.do_build()

    def do_build(self):
        """
        Create the default version of the layer

        :return: a string of the packet with the payload
        """
        if not self.explicit:
            self = next(iter(self))
        pkt = self.self_build()
        for t in self.post_transforms:
            pkt = t(pkt)
        pay = self.do_build_payload()
        if self.raw_packet_cache is None:
            return self.post_build(pkt, pay)
        else:
            return pkt + pay

    def build_padding(self):
        return self.payload.build_padding()

    def build(self):
        """
        Create the current layer

        :return: string of the packet with the payload
        """
        p = self.do_build()
        p += self.build_padding()
        p = self.build_done(p)
        return p

    def post_build(self, pkt, pay):
        """
        DEV: called right after the current layer is build.

        :param str pkt: the current packet (build by self_buil function)
        :param str pay: the packet payload (build by do_build_payload function)
        :return: a string of the packet with the payload
        """
        return pkt + pay

    def build_done(self, p):
        return self.payload.build_done(p)

    def do_build_ps(self):
        p = b""
        pl = []
        q = b""
        for f in self.fields_desc:
            if isinstance(f, ConditionalField) and not f._evalcond(self):
                continue
            p = f.addfield(self, p, self.getfieldval(f.name))
            if isinstance(p, bytes):
                r = p[len(q):]
                q = p
            else:
                r = b""
            pl.append((f, f.i2repr(self, self.getfieldval(f.name)), r))

        pkt, lst = self.payload.build_ps(internal=1)
        p += pkt
        lst.append((self, pl))

        return p, lst

    def build_ps(self, internal=0):
        p, lst = self.do_build_ps()
#        if not internal:
#            pkt = self
#            while pkt.haslayer(conf.padding_layer):
#                pkt = pkt.getlayer(conf.padding_layer)
#                lst.append( (pkt, [ ("loakjkjd", pkt.load, pkt.load) ] ) )
#                p += pkt.load
#                pkt = pkt.payload
        return p, lst

    def canvas_dump(self, layer_shift=0, rebuild=1):
        if PYX == 0:
            raise ImportError("PyX and its dependencies must be installed")
        canvas = pyx.canvas.canvas()
        if rebuild:
            _, t = self.__class__(raw(self)).build_ps()
        else:
            _, t = self.build_ps()
        YTXT = len(t)
        for _, l in t:
            YTXT += len(l)
        YTXT = float(YTXT)
        YDUMP = YTXT

        XSTART = 1
        XDSTART = 10
        y = 0.0
        yd = 0.0
        XMUL = 0.55
        YMUL = 0.4

        backcolor = colgen(0.6, 0.8, 1.0, trans=pyx.color.rgb)
        forecolor = colgen(0.2, 0.5, 0.8, trans=pyx.color.rgb)
#        backcolor=makecol(0.376, 0.729, 0.525, 1.0)

        def hexstr(x):
            return " ".join("%02x" % orb(c) for c in x)

        def make_dump_txt(x, y, txt):
            return pyx.text.text(XDSTART + x * XMUL, (YDUMP - y) * YMUL, r"\tt{%s}" % hexstr(txt), [pyx.text.size.Large])  # noqa: E501

        def make_box(o):
            return pyx.box.rect(o.left(), o.bottom(), o.width(), o.height(), relcenter=(0.5, 0.5))  # noqa: E501

        def make_frame(lst):
            if len(lst) == 1:
                b = lst[0].bbox()
                b.enlarge(pyx.unit.u_pt)
                return b.path()
            else:
                fb = lst[0].bbox()
                fb.enlarge(pyx.unit.u_pt)
                lb = lst[-1].bbox()
                lb.enlarge(pyx.unit.u_pt)
                if len(lst) == 2 and fb.left() > lb.right():
                    return pyx.path.path(pyx.path.moveto(fb.right(), fb.top()),
                                         pyx.path.lineto(fb.left(), fb.top()),
                                         pyx.path.lineto(fb.left(), fb.bottom()),  # noqa: E501
                                         pyx.path.lineto(fb.right(), fb.bottom()),  # noqa: E501
                                         pyx.path.moveto(lb.left(), lb.top()),
                                         pyx.path.lineto(lb.right(), lb.top()),
                                         pyx.path.lineto(lb.right(), lb.bottom()),  # noqa: E501
                                         pyx.path.lineto(lb.left(), lb.bottom()))  # noqa: E501
                else:
                    # XXX
                    gb = lst[1].bbox()
                    if gb != lb:
                        gb.enlarge(pyx.unit.u_pt)
                    kb = lst[-2].bbox()
                    if kb != gb and kb != lb:
                        kb.enlarge(pyx.unit.u_pt)
                    return pyx.path.path(pyx.path.moveto(fb.left(), fb.top()),
                                         pyx.path.lineto(fb.right(), fb.top()),
                                         pyx.path.lineto(fb.right(), kb.bottom()),  # noqa: E501
                                         pyx.path.lineto(lb.right(), kb.bottom()),  # noqa: E501
                                         pyx.path.lineto(lb.right(), lb.bottom()),  # noqa: E501
                                         pyx.path.lineto(lb.left(), lb.bottom()),  # noqa: E501
                                         pyx.path.lineto(lb.left(), gb.top()),
                                         pyx.path.lineto(fb.left(), gb.top()),
                                         pyx.path.closepath(),)

        def make_dump(s, shift=0, y=0, col=None, bkcol=None, large=16):
            c = pyx.canvas.canvas()
            tlist = []
            while s:
                dmp, s = s[:large - shift], s[large - shift:]
                txt = make_dump_txt(shift, y, dmp)
                tlist.append(txt)
                shift += len(dmp)
                if shift >= 16:
                    shift = 0
                    y += 1
            if col is None:
                col = pyx.color.rgb.red
            if bkcol is None:
                col = pyx.color.rgb.white
            c.stroke(make_frame(tlist), [col, pyx.deco.filled([bkcol]), pyx.style.linewidth.Thick])  # noqa: E501
            for txt in tlist:
                c.insert(txt)
            return c, tlist[-1].bbox(), shift, y

        last_shift, last_y = 0, 0.0
        while t:
            bkcol = next(backcolor)
            proto, fields = t.pop()
            y += 0.5
            pt = pyx.text.text(XSTART, (YTXT - y) * YMUL, r"\font\cmssfont=cmss10\cmssfont{%s}" % tex_escape(proto.name), [pyx.text.size.Large])  # noqa: E501
            y += 1
            ptbb = pt.bbox()
            ptbb.enlarge(pyx.unit.u_pt * 2)
            canvas.stroke(ptbb.path(), [pyx.color.rgb.black, pyx.deco.filled([bkcol])])  # noqa: E501
            canvas.insert(pt)
            for field, fval, fdump in fields:
                col = next(forecolor)
                ft = pyx.text.text(XSTART, (YTXT - y) * YMUL, r"\font\cmssfont=cmss10\cmssfont{%s}" % tex_escape(field.name))  # noqa: E501
                if isinstance(field, BitField):
                    fsize = '%sb' % field.size
                else:
                    fsize = '%sB' % len(fdump)
                if (hasattr(field, 'field') and
                        'LE' in field.field.__class__.__name__[:3] or
                        'LE' in field.__class__.__name__[:3]):
                    fsize = r'$\scriptstyle\langle$' + fsize
                st = pyx.text.text(XSTART + 3.4, (YTXT - y) * YMUL, r"\font\cmbxfont=cmssbx10 scaled 600\cmbxfont{%s}" % fsize, [pyx.text.halign.boxright])  # noqa: E501
                if isinstance(fval, str):
                    if len(fval) > 18:
                        fval = fval[:18] + "[...]"
                else:
                    fval = ""
                vt = pyx.text.text(XSTART + 3.5, (YTXT - y) * YMUL, r"\font\cmssfont=cmss10\cmssfont{%s}" % tex_escape(fval))  # noqa: E501
                y += 1.0
                if fdump:
                    dt, target, last_shift, last_y = make_dump(fdump, last_shift, last_y, col, bkcol)  # noqa: E501

                    dtb = dt.bbox()
                    dtb = target
                    vtb = vt.bbox()
                    bxvt = make_box(vtb)
                    bxdt = make_box(dtb)
                    dtb.enlarge(pyx.unit.u_pt)
                    try:
                        if yd < 0:
                            cnx = pyx.connector.curve(bxvt, bxdt, absangle1=0, absangle2=-90)  # noqa: E501
                        else:
                            cnx = pyx.connector.curve(bxvt, bxdt, absangle1=0, absangle2=90)  # noqa: E501
                    except Exception:
                        pass
                    else:
                        canvas.stroke(cnx, [pyx.style.linewidth.thin, pyx.deco.earrow.small, col])  # noqa: E501

                    canvas.insert(dt)

                canvas.insert(ft)
                canvas.insert(st)
                canvas.insert(vt)
            last_y += layer_shift

        return canvas

    def extract_padding(self, s):
        """
        DEV: to be overloaded to extract current layer's padding.

        :param str s: the current layer
        :return: a couple of strings (actual layer, padding)
        """
        return s, None

    def post_dissect(self, s):
        """DEV: is called right after the current layer has been dissected"""
        return s

    def pre_dissect(self, s):
        """DEV: is called right before the current layer is dissected"""
        return s

    def do_dissect(self, s):
        s = raw(s)
        _raw = s
        self.raw_packet_cache_fields = {}
        # Temporary value, used by getfield() in some advanced cases (eg: dot11)  # noqa: E501
        _lr = len(_raw)
        self._tmp_dissect_pos = 0  # How many bytes have already been dissected
        for f in self.fields_desc:
            if not s:
                break
            s, fval = f.getfield(self, s)
            self._tmp_dissect_pos = _lr - len(s)
            # We need to track fields with mutable values to discard
            # .raw_packet_cache when needed.
            if f.islist or f.holds_packets or f.ismutable:
                self.raw_packet_cache_fields[f.name] = f.do_copy(fval)
            self.fields[f.name] = fval
        assert(_raw.endswith(raw(s)))
        del self._tmp_dissect_pos
        self.raw_packet_cache = _raw[:-len(s)] if s else _raw
        self.explicit = 1
        return s

    def do_dissect_payload(self, s):
        """
        Perform the dissection of the layer's payload

        :param str s: the raw layer
        """
        if s:
            cls = self.guess_payload_class(s)
            try:
                p = cls(s, _internal=1, _underlayer=self)
            except KeyboardInterrupt:
                raise
            except Exception:
                if conf.debug_dissector:
                    if issubtype(cls, Packet):
                        log_runtime.error("%s dissector failed" % cls.__name__)
                    else:
                        log_runtime.error("%s.guess_payload_class() returned [%s]" % (self.__class__.__name__, repr(cls)))  # noqa: E501
                    if cls is not None:
                        raise
                p = conf.raw_layer(s, _internal=1, _underlayer=self)
            self.add_payload(p)

    def dissect(self, s):
        s = self.pre_dissect(s)

        s = self.do_dissect(s)

        s = self.post_dissect(s)

        payl, pad = self.extract_padding(s)
        self.do_dissect_payload(payl)
        if pad and conf.padding:
            self.add_payload(conf.padding_layer(pad))

    def guess_payload_class(self, payload):
        """
        DEV: Guesses the next payload class from layer bonds.
        Can be overloaded to use a different mechanism.

        :param str payload: the layer's payload
        :return: the payload class
        """
        for t in self.aliastypes:
            for fval, cls in t.payload_guess:
                if all(hasattr(self, k) and v == self.getfieldval(k)
                       for k, v in six.iteritems(fval)):
                    return cls
        return self.default_payload_class(payload)

    def default_payload_class(self, payload):
        """
        DEV: Returns the default payload class if nothing has been found by the
        guess_payload_class() method.

        :param str payload: the layer's payload
        :return: the default payload class define inside the configuration file
        """
        return conf.raw_layer

    def hide_defaults(self):
        """Removes fields' values that are the same as default values."""
        for k, v in list(self.fields.items()):  # use list(): self.fields is modified in the loop  # noqa: E501
            v = self.fields[k]
            if k in self.default_fields:
                if self.default_fields[k] == v:
                    del self.fields[k]
        self.payload.hide_defaults()

    def clone_with(self, payload=None, **kargs):
        pkt = self.__class__()
        pkt.explicit = 1
        pkt.fields = kargs
        pkt.default_fields = self.copy_fields_dict(self.default_fields)
        pkt.overloaded_fields = self.overloaded_fields.copy()
        pkt.time = self.time
        pkt.underlayer = self.underlayer
        pkt.post_transforms = self.post_transforms
        pkt.raw_packet_cache = self.raw_packet_cache
        pkt.raw_packet_cache_fields = self.copy_fields_dict(
            self.raw_packet_cache_fields
        )
        pkt.wirelen = self.wirelen
        if payload is not None:
            pkt.add_payload(payload)
        return pkt

    def __iter__(self):
        def loop(todo, done, self=self):
            if todo:
                eltname = todo.pop()
                elt = self.getfieldval(eltname)
                if not isinstance(elt, Gen):
                    if self.get_field(eltname).islist:
                        elt = SetGen([elt])
                    else:
                        elt = SetGen(elt)
                for e in elt:
                    done[eltname] = e
                    for x in loop(todo[:], done):
                        yield x
            else:
                if isinstance(self.payload, NoPayload):
                    payloads = [None]
                else:
                    payloads = self.payload
                for payl in payloads:
                    done2 = done.copy()
                    for k in done2:
                        if isinstance(done2[k], VolatileValue):
                            done2[k] = done2[k]._fix()
                    pkt = self.clone_with(payload=payl, **done2)
                    yield pkt

        if self.explicit or self.raw_packet_cache is not None:
            todo = []
            done = self.fields
        else:
            todo = [k for (k, v) in itertools.chain(six.iteritems(self.default_fields),  # noqa: E501
                                                    six.iteritems(self.overloaded_fields))  # noqa: E501
                    if isinstance(v, VolatileValue)] + list(self.fields.keys())
            done = {}
        return loop(todo, done)

    def __iterlen__(self):
        """Predict the total length of the iterator"""
        fields = [key for (key, val) in itertools.chain(six.iteritems(self.default_fields),  # noqa: E501
                  six.iteritems(self.overloaded_fields))
                  if isinstance(val, VolatileValue)] + list(self.fields.keys())
        length = 1
        for field in fields:
            fld, val = self.getfield_and_val(field)
            if hasattr(val, "__iterlen__"):
                length *= val.__iterlen__()
            elif isinstance(val, tuple) and len(val) == 2 and all(hasattr(z, "__int__") for z in val):  # noqa: E501
                length *= (val[1] - val[0])
            elif isinstance(val, list) and not fld.islist:
                len2 = 0
                for x in val:
                    if hasattr(x, "__iterlen__"):
                        len2 += x.__iterlen__()
                    elif isinstance(x, tuple) and len(x) == 2 and all(hasattr(z, "__int__") for z in x):  # noqa: E501
                        len2 += (x[1] - x[0])
                    elif isinstance(x, list):
                        len2 += len(x)
                    else:
                        len2 += 1
                length *= len2 or 1
        if not isinstance(self.payload, NoPayload):
            return length * self.payload.__iterlen__()
        return length

    def __gt__(self, other):
        """True if other is an answer from self (self ==> other)."""
        if isinstance(other, Packet):
            return other < self
        elif isinstance(other, bytes):
            return 1
        else:
            raise TypeError((self, other))

    def __lt__(self, other):
        """True if self is an answer from other (other ==> self)."""
        if isinstance(other, Packet):
            return self.answers(other)
        elif isinstance(other, bytes):
            return 1
        else:
            raise TypeError((self, other))

    def __eq__(self, other):
        if not isinstance(other, self.__class__):
            return False
        for f in self.fields_desc:
            if f not in other.fields_desc:
                return False
            if self.getfieldval(f.name) != other.getfieldval(f.name):
                return False
        return self.payload == other.payload

    def __ne__(self, other):
        return not self.__eq__(other)

    def hashret(self):
        """DEV: returns a string that has the same value for a request and its answer."""  # noqa: E501
        return self.payload.hashret()

    def answers(self, other):
        """DEV: true if self is an answer from other"""
        if other.__class__ == self.__class__:
            return self.payload.answers(other.payload)
        return 0

    def layers(self):
        """returns a list of layer classes (including subclasses) in this packet"""  # noqa: E501
        layers = []
        lyr = self
        while lyr:
            layers.append(lyr.__class__)
            lyr = lyr.payload.getlayer(0, _subclass=True)
        return layers

    def haslayer(self, cls):
        """true if self has a layer that is an instance of cls. Superseded by "cls in self" syntax."""  # noqa: E501
        if self.__class__ == cls or cls in [self.__class__.__name__,
                                            self._name]:
            return True
        for f in self.packetfields:
            fvalue_gen = self.getfieldval(f.name)
            if fvalue_gen is None:
                continue
            if not f.islist:
                fvalue_gen = SetGen(fvalue_gen, _iterpacket=0)
            for fvalue in fvalue_gen:
                if isinstance(fvalue, Packet):
                    ret = fvalue.haslayer(cls)
                    if ret:
                        return ret
        return self.payload.haslayer(cls)

    def getlayer(self, cls, nb=1, _track=None, _subclass=False, **flt):
        """Return the nb^th layer that is an instance of cls, matching flt
values.
        """
        if _subclass:
            match = lambda cls1, cls2: issubclass(cls1, cls2)
        else:
            match = lambda cls1, cls2: cls1 == cls2
        if isinstance(cls, int):
            nb = cls + 1
            cls = None
        if isinstance(cls, str) and "." in cls:
            ccls, fld = cls.split(".", 1)
        else:
            ccls, fld = cls, None
        if cls is None or match(self.__class__, cls) \
           or ccls in [self.__class__.__name__, self._name]:
            if all(self.getfieldval(fldname) == fldvalue
                   for fldname, fldvalue in six.iteritems(flt)):
                if nb == 1:
                    if fld is None:
                        return self
                    else:
                        return self.getfieldval(fld)
                else:
                    nb -= 1
        for f in self.packetfields:
            fvalue_gen = self.getfieldval(f.name)
            if fvalue_gen is None:
                continue
            if not f.islist:
                fvalue_gen = SetGen(fvalue_gen, _iterpacket=0)
            for fvalue in fvalue_gen:
                if isinstance(fvalue, Packet):
                    track = []
                    ret = fvalue.getlayer(cls, nb=nb, _track=track,
                                          _subclass=_subclass, **flt)
                    if ret is not None:
                        return ret
                    nb = track[0]
        return self.payload.getlayer(cls, nb=nb, _track=_track,
                                     _subclass=_subclass, **flt)

    def firstlayer(self):
        q = self
        while q.underlayer is not None:
            q = q.underlayer
        return q

    def __getitem__(self, cls):
        if isinstance(cls, slice):
            lname = cls.start
            if cls.stop:
                ret = self.getlayer(cls.start, nb=cls.stop, **(cls.step or {}))
            else:
                ret = self.getlayer(cls.start, **(cls.step or {}))
        else:
            lname = cls
            ret = self.getlayer(cls)
        if ret is None:
            if isinstance(lname, Packet_metaclass):
                lname = lname.__name__
            elif not isinstance(lname, bytes):
                lname = repr(lname)
            raise IndexError("Layer [%s] not found" % lname)
        return ret

    def __delitem__(self, cls):
        del(self[cls].underlayer.payload)

    def __setitem__(self, cls, val):
        self[cls].underlayer.payload = val

    def __contains__(self, cls):
        """"cls in self" returns true if self has a layer which is an instance of cls."""  # noqa: E501
        return self.haslayer(cls)

    def route(self):
        return self.payload.route()

    def fragment(self, *args, **kargs):
        return self.payload.fragment(*args, **kargs)

    def display(self, *args, **kargs):  # Deprecated. Use show()
        """Deprecated. Use show() method."""
        self.show(*args, **kargs)

    def _show_or_dump(self, dump=False, indent=3, lvl="", label_lvl="", first_call=True):  # noqa: E501
        """
        Internal method that shows or dumps a hierarchical view of a packet.
        Called by show.

        :param dump: determine if it prints or returns the string value
        :param int indent: the size of indentation for each layer
        :param str lvl: additional information about the layer lvl
        :param str label_lvl: additional information about the layer fields
        :param first_call: determine if the current function is the first
        :return: return a hierarchical view if dump, else print it
        """

        if dump:
            from scapy.themes import AnsiColorTheme
            ct = AnsiColorTheme()  # No color for dump output
        else:
            ct = conf.color_theme
        s = "%s%s %s %s \n" % (label_lvl,
                               ct.punct("###["),
                               ct.layer_name(self.name),
                               ct.punct("]###"))
        for f in self.fields_desc:
            if isinstance(f, ConditionalField) and not f._evalcond(self):
                continue
            if isinstance(f, Emph) or f in conf.emph:
                ncol = ct.emph_field_name
                vcol = ct.emph_field_value
            else:
                ncol = ct.field_name
                vcol = ct.field_value
            fvalue = self.getfieldval(f.name)
            if isinstance(fvalue, Packet) or (f.islist and f.holds_packets and isinstance(fvalue, list)):  # noqa: E501
                s += "%s  \\%-10s\\\n" % (label_lvl + lvl, ncol(f.name))
                fvalue_gen = SetGen(fvalue, _iterpacket=0)
                for fvalue in fvalue_gen:
                    s += fvalue._show_or_dump(dump=dump, indent=indent, label_lvl=label_lvl + lvl + "   |", first_call=False)  # noqa: E501
            else:
                begn = "%s  %-10s%s " % (label_lvl + lvl,
                                         ncol(f.name),
                                         ct.punct("="),)
                reprval = f.i2repr(self, fvalue)
                if isinstance(reprval, str):
                    reprval = reprval.replace("\n", "\n" + " " * (len(label_lvl) +  # noqa: E501
                                                                  len(lvl) +
                                                                  len(f.name) +
                                                                  4))
                s += "%s%s\n" % (begn, vcol(reprval))
        if self.payload:
            s += self.payload._show_or_dump(dump=dump, indent=indent, lvl=lvl + (" " * indent * self.show_indent), label_lvl=label_lvl, first_call=False)  # noqa: E501

        if first_call and not dump:
            print(s)
        else:
            return s

    def show(self, dump=False, indent=3, lvl="", label_lvl=""):
        """
        Prints or returns (when "dump" is true) a hierarchical view of the
        packet.

        :param dump: determine if it prints or returns the string value
        :param int indent: the size of indentation for each layer
        :param str lvl: additional information about the layer lvl
        :param str label_lvl: additional information about the layer fields
        :return: return a hierarchical view if dump, else print it
        """
        return self._show_or_dump(dump, indent, lvl, label_lvl)

    def show2(self, dump=False, indent=3, lvl="", label_lvl=""):
        """
        Prints or returns (when "dump" is true) a hierarchical view of an
        assembled version of the packet, so that automatic fields are
        calculated (checksums, etc.)

        :param dump: determine if it prints or returns the string value
        :param int indent: the size of indentation for each layer
        :param str lvl: additional information about the layer lvl
        :param str label_lvl: additional information about the layer fields
        :return: return a hierarchical view if dump, else print it
        """
        return self.__class__(raw(self)).show(dump, indent, lvl, label_lvl)

    def sprintf(self, fmt, relax=1):
        """sprintf(format, [relax=1]) -> str
where format is a string that can include directives. A directive begins and
ends by % and has the following format %[fmt[r],][cls[:nb].]field%.

fmt is a classic printf directive, "r" can be appended for raw substitution
(ex: IP.flags=0x18 instead of SA), nb is the number of the layer we want
(ex: for IP/IP packets, IP:2.src is the src of the upper IP layer).
Special case : "%.time%" is the creation time.
Ex : p.sprintf("%.time% %-15s,IP.src% -> %-15s,IP.dst% %IP.chksum% "
               "%03xr,IP.proto% %r,TCP.flags%")

Moreover, the format string can include conditional statements. A conditional
statement looks like : {layer:string} where layer is a layer name, and string
is the string to insert in place of the condition if it is true, i.e. if layer
is present. If layer is preceded by a "!", the result is inverted. Conditions
can be imbricated. A valid statement can be :
  p.sprintf("This is a{TCP: TCP}{UDP: UDP}{ICMP:n ICMP} packet")
  p.sprintf("{IP:%IP.dst% {ICMP:%ICMP.type%}{TCP:%TCP.dport%}}")

A side effect is that, to obtain "{" and "}" characters, you must use
"%(" and "%)".
"""

        escape = {"%": "%",
                  "(": "{",
                  ")": "}"}

        # Evaluate conditions
        while "{" in fmt:
            i = fmt.rindex("{")
            j = fmt[i + 1:].index("}")
            cond = fmt[i + 1:i + j + 1]
            k = cond.find(":")
            if k < 0:
                raise Scapy_Exception("Bad condition in format string: [%s] (read sprintf doc!)" % cond)  # noqa: E501
            cond, format_ = cond[:k], cond[k + 1:]
            res = False
            if cond[0] == "!":
                res = True
                cond = cond[1:]
            if self.haslayer(cond):
                res = not res
            if not res:
                format_ = ""
            fmt = fmt[:i] + format_ + fmt[i + j + 2:]

        # Evaluate directives
        s = ""
        while "%" in fmt:
            i = fmt.index("%")
            s += fmt[:i]
            fmt = fmt[i + 1:]
            if fmt and fmt[0] in escape:
                s += escape[fmt[0]]
                fmt = fmt[1:]
                continue
            try:
                i = fmt.index("%")
                sfclsfld = fmt[:i]
                fclsfld = sfclsfld.split(",")
                if len(fclsfld) == 1:
                    f = "s"
                    clsfld = fclsfld[0]
                elif len(fclsfld) == 2:
                    f, clsfld = fclsfld
                else:
                    raise Scapy_Exception
                if "." in clsfld:
                    cls, fld = clsfld.split(".")
                else:
                    cls = self.__class__.__name__
                    fld = clsfld
                num = 1
                if ":" in cls:
                    cls, num = cls.split(":")
                    num = int(num)
                fmt = fmt[i + 1:]
            except Exception:
                raise Scapy_Exception("Bad format string [%%%s%s]" % (fmt[:25], fmt[25:] and "..."))  # noqa: E501
            else:
                if fld == "time":
                    val = time.strftime("%H:%M:%S.%%06i", time.localtime(self.time)) % int((self.time - int(self.time)) * 1000000)  # noqa: E501
                elif cls == self.__class__.__name__ and hasattr(self, fld):
                    if num > 1:
                        val = self.payload.sprintf("%%%s,%s:%s.%s%%" % (f, cls, num - 1, fld), relax)  # noqa: E501
                        f = "s"
                    elif f[-1] == "r":  # Raw field value
                        val = getattr(self, fld)
                        f = f[:-1]
                        if not f:
                            f = "s"
                    else:
                        val = getattr(self, fld)
                        if fld in self.fieldtype:
                            val = self.fieldtype[fld].i2repr(self, val)
                else:
                    val = self.payload.sprintf("%%%s%%" % sfclsfld, relax)
                    f = "s"
                s += ("%" + f) % val

        s += fmt
        return s

    def mysummary(self):
        """DEV: can be overloaded to return a string that summarizes the layer.
           Only one mysummary() is used in a whole packet summary: the one of the upper layer,  # noqa: E501
           except if a mysummary() also returns (as a couple) a list of layers whose  # noqa: E501
           mysummary() must be called if they are present."""
        return ""

    def _do_summary(self):
        found, s, needed = self.payload._do_summary()
        ret = ""
        if not found or self.__class__ in needed:
            ret = self.mysummary()
            if isinstance(ret, tuple):
                ret, n = ret
                needed += n
        if ret or needed:
            found = 1
        if not ret:
            ret = self.__class__.__name__ if self.show_summary else ""
        if self.__class__ in conf.emph:
            impf = []
            for f in self.fields_desc:
                if f in conf.emph:
                    impf.append("%s=%s" % (f.name, f.i2repr(self, self.getfieldval(f.name))))  # noqa: E501
            ret = "%s [%s]" % (ret, " ".join(impf))
        if ret and s:
            ret = "%s / %s" % (ret, s)
        else:
            ret = "%s%s" % (ret, s)
        return found, ret, needed

    def summary(self, intern=0):
        """Prints a one line summary of a packet."""
        return self._do_summary()[1]

    def lastlayer(self, layer=None):
        """Returns the uppest layer of the packet"""
        return self.payload.lastlayer(self)

    def decode_payload_as(self, cls):
        """Reassembles the payload and decode it using another packet class"""
        s = raw(self.payload)
        self.payload = cls(s, _internal=1, _underlayer=self)
        pp = self
        while pp.underlayer is not None:
            pp = pp.underlayer
        self.payload.dissection_done(pp)

    def command(self):
        """
        Returns a string representing the command you have to type to
        obtain the same packet
        """
        f = []
        for fn, fv in self.fields.items():
            fld = self.get_field(fn)
            if isinstance(fv, (list, dict, set)) and len(fv) == 0:
                continue
            if isinstance(fv, Packet):
                fv = fv.command()
            elif fld.islist and fld.holds_packets and isinstance(fv, list):
                fv = "[%s]" % ",".join(map(Packet.command, fv))
            elif isinstance(fld, FlagsField):
                fv = int(fv)
            else:
                fv = repr(fv)
            f.append("%s=%s" % (fn, fv))
        c = "%s(%s)" % (self.__class__.__name__, ", ".join(f))
        pc = self.payload.command()
        if pc:
            c += "/" + pc
        return c


class NoPayload(Packet):
    def __new__(cls, *args, **kargs):
        singl = cls.__dict__.get("__singl__")
        if singl is None:
            cls.__singl__ = singl = Packet.__new__(cls)
            Packet.__init__(singl)
        return singl

    def __init__(self, *args, **kargs):
        pass

    def dissection_done(self, pkt):
        return

    def add_payload(self, payload):
        raise Scapy_Exception("Can't add payload to NoPayload instance")

    def remove_payload(self):
        pass

    def add_underlayer(self, underlayer):
        pass

    def remove_underlayer(self, other):
        pass

    def copy(self):
        return self

    def clear_cache(self):
        pass

    def __repr__(self):
        return ""

    def __str__(self):
        return ""

    def __bytes__(self):
        return b""

    def __nonzero__(self):
        return False
    __bool__ = __nonzero__

    def do_build(self):
        return b""

    def build(self):
        return b""

    def build_padding(self):
        return b""

    def build_done(self, p):
        return p

    def build_ps(self, internal=0):
        return b"", []

    def getfieldval(self, attr):
        raise AttributeError(attr)

    def getfield_and_val(self, attr):
        raise AttributeError(attr)

    def setfieldval(self, attr, val):
        raise AttributeError(attr)

    def delfieldval(self, attr):
        raise AttributeError(attr)

    def hide_defaults(self):
        pass

    def __iter__(self):
        return iter([])

    def __eq__(self, other):
        if isinstance(other, NoPayload):
            return True
        return False

    def hashret(self):
        return b""

    def answers(self, other):
        return isinstance(other, NoPayload) or isinstance(other, conf.padding_layer)  # noqa: E501

    def haslayer(self, cls):
        return 0

    def getlayer(self, cls, nb=1, _track=None, **flt):
        if _track is not None:
            _track.append(nb)
        return None

    def fragment(self, *args, **kargs):
        raise Scapy_Exception("cannot fragment this packet")

    def show(self, indent=3, lvl="", label_lvl=""):
        pass

    def sprintf(self, fmt, relax):
        if relax:
            return "??"
        else:
            raise Scapy_Exception("Format not found [%s]" % fmt)

    def _do_summary(self):
        return 0, "", []

    def layers(self):
        return []

    def lastlayer(self, layer):
        return layer

    def command(self):
        return ""

    def route(self):
        return (None, None, None)


####################
#  packet classes  #
####################


class Raw(Packet):
    name = "Raw"
    fields_desc = [StrField("load", "")]

    def answers(self, other):
        return 1
#        s = raw(other)
#        t = self.load
#        l = min(len(s), len(t))
#        return  s[:l] == t[:l]

    def mysummary(self):
        cs = conf.raw_summary
        if cs:
            if callable(cs):
                return "Raw %s" % cs(self.load)
            else:
                return "Raw %r" % self.load
        return Packet.mysummary(self)


class Padding(Raw):
    name = "Padding"

    def self_build(self):
        return b""

    def build_padding(self):
        return (raw(self.load) if self.raw_packet_cache is None
                else self.raw_packet_cache) + self.payload.build_padding()


conf.raw_layer = Raw
conf.padding_layer = Padding
if conf.default_l2 is None:
    conf.default_l2 = Raw

#################
#  Bind layers  #
#################


def bind_bottom_up(lower, upper, __fval=None, **fval):
    """Bind 2 layers for dissection.
    The upper layer will be chosen for dissection on top of the lower layer, if
    ALL the passed arguments are validated. If multiple calls are made with the same  # noqa: E501
    layers, the last one will be used as default.

    ex:
        >>> bind_bottom_up(Ether, SNAP, type=0x1234)
        >>> Ether(b'\xff\xff\xff\xff\xff\xff\xd0P\x99V\xdd\xf9\x124\x00\x00\x00\x00\x00')  # noqa: E501
        <Ether  dst=ff:ff:ff:ff:ff:ff src=d0:50:99:56:dd:f9 type=0x1234 |<SNAP  OUI=0x0 code=0x0 |>>  # noqa: E501
    """
    if __fval is not None:
        fval.update(__fval)
    lower.payload_guess = lower.payload_guess[:]
    lower.payload_guess.append((fval, upper))


def bind_top_down(lower, upper, __fval=None, **fval):
    """Bind 2 layers for building.
    When the upper layer is added as a payload of the lower layer, all the arguments  # noqa: E501
    will be applied to them.

    ex:
        >>> bind_top_down(Ether, SNAP, type=0x1234)
        >>> Ether()/SNAP()
        <Ether  type=0x1234 |<SNAP  |>>
    """
    if __fval is not None:
        fval.update(__fval)
    upper._overload_fields = upper._overload_fields.copy()
    upper._overload_fields[lower] = fval


@conf.commands.register
def bind_layers(lower, upper, __fval=None, **fval):
    """Bind 2 layers on some specific fields' values. It makes the packet being built  # noqa: E501
    and dissected when the arguments are present.

    This functions calls both bind_bottom_up and bind_top_down, with all passed arguments.  # noqa: E501
    Please have a look at their docs:
     - help(bind_bottom_up)
     - help(bind_top_down)
     """
    if __fval is not None:
        fval.update(__fval)
    bind_top_down(lower, upper, **fval)
    bind_bottom_up(lower, upper, **fval)


def split_bottom_up(lower, upper, __fval=None, **fval):
    """This call un-links an association that was made using bind_bottom_up.
    Have a look at help(bind_bottom_up)
    """
    if __fval is not None:
        fval.update(__fval)

    def do_filter(params, cls):
        params_is_invalid = any(
            k not in params or params[k] != v for k, v in six.iteritems(fval)
        )
        return cls != upper or params_is_invalid
    lower.payload_guess = [x for x in lower.payload_guess if do_filter(*x)]


def split_top_down(lower, upper, __fval=None, **fval):
    """This call un-links an association that was made using bind_top_down.
    Have a look at help(bind_top_down)
    """
    if __fval is not None:
        fval.update(__fval)
    if lower in upper._overload_fields:
        ofval = upper._overload_fields[lower]
        if any(k not in ofval or ofval[k] != v for k, v in six.iteritems(fval)):  # noqa: E501
            return
        upper._overload_fields = upper._overload_fields.copy()
        del(upper._overload_fields[lower])


@conf.commands.register
def split_layers(lower, upper, __fval=None, **fval):
    """Split 2 layers previously bound.
    This call un-links calls bind_top_down and bind_bottom_up. It is the opposite of  # noqa: E501
    bind_layers.

    Please have a look at their docs:
     - help(split_bottom_up)
     - help(split_top_down)
    """
    if __fval is not None:
        fval.update(__fval)
    split_bottom_up(lower, upper, **fval)
    split_top_down(lower, upper, **fval)


@conf.commands.register
def explore(layer=None):
    """Function used to discover the Scapy layers and protocols.
    It helps to see which packets exists in contrib or layer files.

    params:
     - layer: If specified, the function will explore the layer. If not,
              the GUI mode will be activated, to browse the available layers
    """
    if layer is None:  # GUI MODE
        if not conf.interactive:
            raise Scapy_Exception("explore() GUI-mode cannot be run in "
                                  "interactive mode. Please provide a "
                                  "'layer' parameter !")
        # 0 - Imports
        try:
            import prompt_toolkit
        except ImportError:
            raise ImportError("prompt_toolkit is not installed ! "
                              "You may install IPython, which contains it, via"
                              " `pip install ipython`")
        if not _version_checker(prompt_toolkit, (2, 0)):
            raise ImportError("prompt_toolkit >= 2.0.0 is required !")
        # Only available with prompt_toolkit > 2.0, not released on PyPi yet
        from prompt_toolkit.shortcuts.dialogs import radiolist_dialog, \
            yes_no_dialog
        from prompt_toolkit.formatted_text import HTML
        # 1 - Ask for layer or contrib
        is_layer = yes_no_dialog(
            title="Scapy v%s" % conf.version,
            text=HTML(
                six.text_type(
                    '<style bg="white" fg="red">Chose the type of packets'
                    ' you want to explore:</style>'
                )
            ),
            yes_text=six.text_type("Layers"),
            no_text=six.text_type("Contribs"))
        # 2 - Retrieve list of Packets
        if is_layer is True:
            # Get all loaded layers
            _radio_values = conf.layers.layers()
            # Restrict to layers-only (not contribs) + packet.py and asn1*.py
            _radio_values = [x for x in _radio_values if ("layers" in x[0] or
                                                          "packet" in x[0] or
                                                          "asn1" in x[0])]
        elif is_layer is False:
            # Get all existing contribs
            from scapy.main import list_contrib
            _radio_values = list_contrib(ret=True)
            _radio_values = [(x['name'], x['description'])
                             for x in _radio_values]
            # Remove very specific modules
            _radio_values = [x for x in _radio_values if not ("can" in x[0])]
        else:
            # Escape was pressed
            return
        # Python 2 compat
        if six.PY2:
            _radio_values = [(six.text_type(x), six.text_type(y))
                             for x, y in _radio_values]
        # 3 - Ask for the layer/contrib module to explore
        result = radiolist_dialog(
            values=_radio_values,
            title="Scapy v%s" % conf.version,
            text=HTML(
                six.text_type(
                    '<style bg="white" fg="red">Please select a layer among'
                    ' the following, to see all packets contained in'
                    ' it:</style>'
                )
            ))
        if result is None:
            return  # User pressed "Cancel"
        # 4 - (Contrib only): load contrib
        if not is_layer:
            from scapy.main import load_contrib
            load_contrib(result)
            result = "scapy.contrib." + result
    else:  # NON-GUI MODE
        # We handle layer as a short layer name, full layer name
        # or the module itself
        if isinstance(layer, types.ModuleType):
            layer = layer.__name__
        if isinstance(layer, str):
            if layer.startswith("scapy.layers."):
                result = layer
            else:
                if layer.startswith("scapy.contrib."):
                    layer = layer.replace("scapy.contrib.", "")
                from scapy.main import load_contrib
                load_contrib(layer)
                result_layer, result_contrib = (("scapy.layers.%s" % layer),
                                                ("scapy.contrib.%s" % layer))
                if result_layer in conf.layers.ldict:
                    result = result_layer
                elif result_contrib in conf.layers.ldict:
                    result = result_contrib
                else:
                    raise Scapy_Exception("Unknown scapy module '%s'" % layer)
    # COMMON PART
    # Get the list of all Packets contained in that module
    try:
        all_layers = conf.layers.ldict[result]
    except KeyError:
        raise Scapy_Exception("Unknown scapy module '%s'" % layer)
    # Print
    print(conf.color_theme.layer_name("Packets contained in %s:" % result))
    rtlst = [(lay.__name__ or "", lay._name or "") for lay in all_layers]
    print(pretty_list(rtlst, [("Class", "Name")], borders=True))


@conf.commands.register
def ls(obj=None, case_sensitive=False, verbose=False):
    """List  available layers, or infos on a given layer class or name.
    params:
     - obj: Packet / packet name to use
     - case_sensitive: if obj is a string, is it case sensitive?
     - verbose
    """
    is_string = isinstance(obj, six.string_types)

    if obj is None or is_string:
        tip = False
        if obj is None:
            tip = True
            all_layers = sorted(conf.layers, key=lambda x: x.__name__)
        else:
            pattern = re.compile(obj, 0 if case_sensitive else re.I)
            # We first order by accuracy, then length
            if case_sensitive:
                sorter = lambda x: (x.__name__.index(obj), len(x.__name__))
            else:
                obj = obj.lower()
                sorter = lambda x: (x.__name__.lower().index(obj),
                                    len(x.__name__))
            all_layers = sorted((layer for layer in conf.layers
                                 if (isinstance(layer.__name__, str) and
                                     pattern.search(layer.__name__)) or
                                 (isinstance(layer.name, str) and
                                     pattern.search(layer.name))),
                                key=sorter)
        for layer in all_layers:
            print("%-10s : %s" % (layer.__name__, layer._name))
        if tip and conf.interactive:
            print()
            print("TIP: You may use explore() to navigate through all "
                  "layers using a clear GUI")

    else:
        is_pkt = isinstance(obj, Packet)
        if issubtype(obj, Packet) or is_pkt:
            for f in obj.fields_desc:
                cur_fld = f
                attrs = []
                long_attrs = []
                while isinstance(cur_fld, (Emph, ConditionalField)):
                    if isinstance(cur_fld, ConditionalField):
                        attrs.append(cur_fld.__class__.__name__[:4])
                    cur_fld = cur_fld.fld
                if verbose and isinstance(cur_fld, EnumField) \
                   and hasattr(cur_fld, "i2s"):
                    if len(cur_fld.i2s) < 50:
                        long_attrs.extend(
                            "%s: %d" % (strval, numval)
                            for numval, strval in
                            sorted(six.iteritems(cur_fld.i2s))
                        )
                elif isinstance(cur_fld, MultiEnumField):
                    fld_depend = cur_fld.depends_on(obj.__class__
                                                    if is_pkt else obj)
                    attrs.append("Depends on %s" % fld_depend.name)
                    if verbose:
                        cur_i2s = cur_fld.i2s_multi.get(
                            cur_fld.depends_on(obj if is_pkt else obj()), {}
                        )
                        if len(cur_i2s) < 50:
                            long_attrs.extend(
                                "%s: %d" % (strval, numval)
                                for numval, strval in
                                sorted(six.iteritems(cur_i2s))
                            )
                elif verbose and isinstance(cur_fld, FlagsField):
                    names = cur_fld.names
                    long_attrs.append(", ".join(names))
                class_name = "%s (%s)" % (
                    cur_fld.__class__.__name__,
                    ", ".join(attrs)) if attrs else cur_fld.__class__.__name__
                if isinstance(cur_fld, BitField):
                    class_name += " (%d bit%s)" % (cur_fld.size,
                                                   "s" if cur_fld.size > 1
                                                   else "")
                print("%-10s : %-35s =" % (f.name, class_name), end=' ')
                if is_pkt:
                    print("%-15r" % (getattr(obj, f.name),), end=' ')
                print("(%r)" % (f.default,))
                for attr in long_attrs:
                    print("%-15s%s" % ("", attr))
            if is_pkt and not isinstance(obj.payload, NoPayload):
                print("--")
                ls(obj.payload)

        else:
            print("Not a packet class or name. Type 'ls()' to list packet classes.")  # noqa: E501


#############
#  Fuzzing  #
#############

@conf.commands.register
def fuzz(p, _inplace=0):
    """Transform a layer into a fuzzy layer by replacing some default values by random objects"""  # noqa: E501
    if not _inplace:
        p = p.copy()
    q = p
    while not isinstance(q, NoPayload):
        for f in q.fields_desc:
            if isinstance(f, PacketListField):
                for r in getattr(q, f.name):
                    print("fuzzing", repr(r))
                    fuzz(r, _inplace=1)
            elif f.default is not None:
                if not isinstance(f, ConditionalField) or f._evalcond(q):
                    rnd = f.randval()
                    if rnd is not None:
                        q.default_fields[f.name] = rnd
        q = q.payload
    return p
