# SPDX-License-Identifier: GPL-2.0-or-later
# This file is part of Scapy
# See https://scapy.net/ for more information
# Copyright (C) 2009 Jochen Bartl

# scapy.contrib.description = Enhanced Interior Gateway Routing Protocol (EIGRP)
# scapy.contrib.status = loads

"""
    EIGRP Scapy Extension
    ~~~~~~~~~~~~~~~~~~~~~

    :version:   2009-08-13
    :e-mail:    lobo@c3a.de / jochen.bartl@gmail.com

    :TODO

    - Replace TLV code with a more generic solution
        * http://trac.secdev.org/scapy/ticket/90
    - Write function for calculating authentication data

    :Thanks:

    - TLV code derived from the CDP implementation of scapy. (Thanks to Nicolas Bareil and Arnaud Ebalard)
        http://trac.secdev.org/scapy/ticket/18
    - IOS / EIGRP Version Representation FIX by Dirk Loss
"""
import socket
import struct

from scapy.packet import Packet
from scapy.fields import StrField, IPField, XShortField, FieldLenField, \
    StrLenField, IntField, ByteEnumField, ByteField, ConditionalField, \
    FlagsField, IP6Field, PacketListField, ShortEnumField, \
    ShortField, StrFixedLenField, ThreeBytesField
from scapy.layers.inet import IP, checksum, bind_layers
from scapy.layers.inet6 import IPv6
from scapy.compat import chb
from scapy.config import conf
from scapy.utils import inet_aton, inet_ntoa
from scapy.pton_ntop import inet_ntop, inet_pton
from scapy.error import warning, Scapy_Exception
from scapy.volatile import RandShort, RandString


class EigrpIPField(StrField, IPField):
    """
    This is a special field type for handling ip addresses of destination networks in internal and
    external route updates.

    EIGRP removes zeros from the host portion of the ip address if the netmask is 8, 16 or 24 bits.
    """

    __slots__ = ["length_from"]

    def __init__(self, name, default, length=None, length_from=None):
        StrField.__init__(self, name, default)
        self.length_from = length_from
        if length is not None:
            self.length_from = lambda pkt, length=length: length

    def h2i(self, pkt, x):
        return IPField.h2i(self, pkt, x)

    def i2m(self, pkt, x):
        x = inet_aton(x)
        tmp_len = self.length_from(pkt)

        if tmp_len <= 8:
            return x[:1]
        elif tmp_len <= 16:
            return x[:2]
        elif tmp_len <= 24:
            return x[:3]
        else:
            return x

    def m2i(self, pkt, x):
        tmp_len = self.length_from(pkt)

        if tmp_len <= 8:
            x += b"\x00\x00\x00"
        elif tmp_len <= 16:
            x += b"\x00\x00"
        elif tmp_len <= 24:
            x += b"\x00"

        return inet_ntoa(x)

    def prefixlen_to_bytelen(self, tmp_len):
        if tmp_len <= 8:
            tmp_len = 1
        elif tmp_len <= 16:
            tmp_len = 2
        elif tmp_len <= 24:
            tmp_len = 3
        else:
            tmp_len = 4

        return tmp_len

    def i2len(self, pkt, x):
        tmp_len = self.length_from(pkt)
        tmp_len = self.prefixlen_to_bytelen(tmp_len)
        return tmp_len

    def getfield(self, pkt, s):
        tmp_len = self.length_from(pkt)
        tmp_len = self.prefixlen_to_bytelen(tmp_len)
        return s[tmp_len:], self.m2i(pkt, s[:tmp_len])

    def randval(self):
        return IPField.randval(self)


class EigrpIP6Field(StrField, IP6Field):
    """
    This is a special field type for handling ip addresses of destination networks in internal and
    external route updates.

    """

    __slots__ = ["length_from"]

    def __init__(self, name, default, length=None, length_from=None):
        StrField.__init__(self, name, default)
        self.length_from = length_from
        if length is not None:
            self.length_from = lambda pkt, length=length: length

    def any2i(self, pkt, x):
        return IP6Field.any2i(self, pkt, x)

    def i2repr(self, pkt, x):
        return IP6Field.i2repr(self, pkt, x)

    def h2i(self, pkt, x):
        return IP6Field.h2i(self, pkt, x)

    def i2m(self, pkt, x):
        x = inet_pton(socket.AF_INET6, x)
        tmp_len = self.length_from(pkt)
        tmp_len = self.prefixlen_to_bytelen(tmp_len)

        return x[:tmp_len]

    def m2i(self, pkt, x):
        tmp_len = self.length_from(pkt)

        prefixlen = self.prefixlen_to_bytelen(tmp_len)
        if tmp_len > 128:
            warning("EigrpIP6Field: Prefix length is > 128. Dissection of this packet will fail")  # noqa: E501
        else:
            pad = b"\x00" * (16 - prefixlen)
            x += pad

        return inet_ntop(socket.AF_INET6, x)

    def prefixlen_to_bytelen(self, plen):
        plen = plen // 8

        if plen < 16:
            plen += 1

        return plen

    def i2len(self, pkt, x):
        tmp_len = self.length_from(pkt)
        tmp_len = self.prefixlen_to_bytelen(tmp_len)
        return tmp_len

    def getfield(self, pkt, s):
        tmp_len = self.length_from(pkt)
        tmp_len = self.prefixlen_to_bytelen(tmp_len)
        return s[tmp_len:], self.m2i(pkt, s[:tmp_len])

    def randval(self):
        return IP6Field.randval(self)


class EIGRPGeneric(Packet):
    name = "EIGRP Generic TLV"
    fields_desc = [XShortField("type", 0x0000),
                   FieldLenField("len", None, "value", "!H", adjust=lambda pkt, x: x + 4),  # noqa: E501
                   StrLenField("value", b"\x00", length_from=lambda pkt: pkt.len - 4)]  # noqa: E501

    def guess_payload_class(self, p):
        return conf.padding_layer


class EIGRPParam(EIGRPGeneric):
    name = "EIGRP Parameters"
    fields_desc = [XShortField("type", 0x0001),
                   ShortField("len", 12),
                   # Bandwidth
                   ByteField("k1", 1),
                   # Load
                   ByteField("k2", 0),
                   # Delay
                   ByteField("k3", 1),
                   # Reliability
                   ByteField("k4", 0),
                   # MTU
                   ByteField("k5", 0),
                   ByteField("reserved", 0),
                   ShortField("holdtime", 15)
                   ]


class EIGRPAuthData(EIGRPGeneric):
    name = "EIGRP Authentication Data"
    fields_desc = [XShortField("type", 0x0002),
                   FieldLenField("len", None, "authdata", "!H", adjust=lambda pkt, x: x + 24),  # noqa: E501
                   ShortEnumField("authtype", 2, {2: "MD5"}),
                   ShortField("keysize", None),
                   IntField("keyid", 1),
                   StrFixedLenField("nullpad", b"\x00" * 12, 12),
                   StrLenField("authdata", RandString(16), length_from=lambda pkt: pkt.keysize)  # noqa: E501
                   ]

    def post_build(self, p, pay):
        p += pay

        if self.keysize is None:
            keysize = len(self.authdata)
            p = p[:6] + chb((keysize >> 8) & 0xff) + chb(keysize & 0xff) + p[8:]  # noqa: E501

        return p


class EIGRPSeq(EIGRPGeneric):
    name = "EIGRP Sequence"
    fields_desc = [XShortField("type", 0x0003),
                   ShortField("len", None),
                   ByteField("addrlen", 4),
                   ConditionalField(IPField("ipaddr", "192.168.0.1"),
                                    lambda pkt:pkt.addrlen == 4),
                   ConditionalField(IP6Field("ip6addr", "2001::"),
                                    lambda pkt:pkt.addrlen == 16)
                   ]

    def post_build(self, p, pay):
        p += pay

        if self.len is None:
            tmp_len = len(p)
            tmp_p = p[:2] + chb((tmp_len >> 8) & 0xff)
            p = tmp_p + chb(tmp_len & 0xff) + p[4:]

        return p


class ShortVersionField(ShortField):
    def i2repr(self, pkt, x):
        try:
            minor = x & 0xff
            major = (x >> 8) & 0xff
        except TypeError:
            return "unknown"
        else:
            # We print a leading 'v' so that these values don't look like floats  # noqa: E501
            return "v%s.%s" % (major, minor)

    def h2i(self, pkt, x):
        """The field accepts string values like v12.1, v1.1 or integer values.
           String values have to start with a "v" followed by a
           floating point number. Valid numbers are between 0 and 255.

        """

        if isinstance(x, str) and x.startswith("v") and len(x) <= 8:
            major = int(x.split(".")[0][1:])
            minor = int(x.split(".")[1])

            return (major << 8) | minor

        elif isinstance(x, int) and 0 <= x <= 65535:
            return x
        else:
            if not hasattr(self, "default"):
                return x
            if self.default is not None:
                warning("set value to default. Format of %r is invalid", x)
                return self.default
            else:
                raise Scapy_Exception("Format of value is invalid")

    def randval(self):
        return RandShort()


class EIGRPSwVer(EIGRPGeneric):
    name = "EIGRP Software Version"
    fields_desc = [XShortField("type", 0x0004),
                   ShortField("len", 8),
                   ShortVersionField("ios", "v12.0"),
                   ShortVersionField("eigrp", "v1.2")
                   ]


class EIGRPNms(EIGRPGeneric):
    name = "EIGRP Next Multicast Sequence"
    fields_desc = [XShortField("type", 0x0005),
                   ShortField("len", 8),
                   IntField("nms", 2)
                   ]


# Don't get confused by the term "receive-only". This flag is always set, when you configure  # noqa: E501
# one of the stub options. It's also the only flag set, when you configure "eigrp stub receive-only".  # noqa: E501
_EIGRP_STUB_FLAGS = ["connected", "static", "summary", "receive-only", "redistributed", "leak-map"]  # noqa: E501


class EIGRPStub(EIGRPGeneric):
    name = "EIGRP Stub Router"
    fields_desc = [XShortField("type", 0x0006),
                   ShortField("len", 6),
                   FlagsField("flags", 0x000d, 16, _EIGRP_STUB_FLAGS)]

# Delay 0xffffffff == Destination Unreachable


class EIGRPIntRoute(EIGRPGeneric):
    name = "EIGRP Internal Route"
    fields_desc = [XShortField("type", 0x0102),
                   FieldLenField("len", None, "dst", "!H", adjust=lambda pkt, x: x + 25),  # noqa: E501
                   IPField("nexthop", "192.168.0.0"),
                   IntField("delay", 128000),
                   IntField("bandwidth", 256),
                   ThreeBytesField("mtu", 1500),
                   ByteField("hopcount", 0),
                   ByteField("reliability", 255),
                   ByteField("load", 0),
                   XShortField("reserved", 0),
                   ByteField("prefixlen", 24),
                   EigrpIPField("dst", "192.168.1.0", length_from=lambda pkt: pkt.prefixlen),  # noqa: E501
                   ]


_EIGRP_EXTERNAL_PROTOCOL_ID = {
    0x01: "IGRP",
    0x02: "EIGRP",
    0x03: "Static Route",
    0x04: "RIP",
    0x05: "Hello",
    0x06: "OSPF",
    0x07: "IS-IS",
    0x08: "EGP",
    0x09: "BGP",
    0x0A: "IDRP",
    0x0B: "Connected Link"
}

_EIGRP_EXTROUTE_FLAGS = ["external", "candidate-default"]


class EIGRPExtRoute(EIGRPGeneric):
    name = "EIGRP External Route"
    fields_desc = [XShortField("type", 0x0103),
                   FieldLenField("len", None, "dst", "!H", adjust=lambda pkt, x: x + 45),  # noqa: E501
                   IPField("nexthop", "192.168.0.0"),
                   IPField("originrouter", "192.168.0.1"),
                   IntField("originasn", 0),
                   IntField("tag", 0),
                   IntField("externalmetric", 0),
                   ShortField("reserved", 0),
                   ByteEnumField("extprotocolid", 3, _EIGRP_EXTERNAL_PROTOCOL_ID),  # noqa: E501
                   FlagsField("flags", 0, 8, _EIGRP_EXTROUTE_FLAGS),
                   IntField("delay", 0),
                   IntField("bandwidth", 256),
                   ThreeBytesField("mtu", 1500),
                   ByteField("hopcount", 0),
                   ByteField("reliability", 255),
                   ByteField("load", 0),
                   XShortField("reserved2", 0),
                   ByteField("prefixlen", 24),
                   EigrpIPField("dst", "192.168.1.0", length_from=lambda pkt: pkt.prefixlen)  # noqa: E501
                   ]


class EIGRPv6IntRoute(EIGRPGeneric):
    name = "EIGRP for IPv6 Internal Route"
    fields_desc = [XShortField("type", 0x0402),
                   FieldLenField("len", None, "dst", "!H", adjust=lambda pkt, x: x + 37),  # noqa: E501
                   IP6Field("nexthop", "::"),
                   IntField("delay", 128000),
                   IntField("bandwidth", 256000),
                   ThreeBytesField("mtu", 1500),
                   ByteField("hopcount", 1),
                   ByteField("reliability", 255),
                   ByteField("load", 0),
                   XShortField("reserved", 0),
                   ByteField("prefixlen", 16),
                   EigrpIP6Field("dst", "2001::", length_from=lambda pkt: pkt.prefixlen)  # noqa: E501
                   ]


class EIGRPv6ExtRoute(EIGRPGeneric):
    name = "EIGRP for IPv6 External Route"
    fields_desc = [XShortField("type", 0x0403),
                   FieldLenField("len", None, "dst", "!H", adjust=lambda pkt, x: x + 57),  # noqa: E501
                   IP6Field("nexthop", "::"),
                   IPField("originrouter", "192.168.0.1"),
                   IntField("originasn", 0),
                   IntField("tag", 0),
                   IntField("externalmetric", 0),
                   ShortField("reserved", 0),
                   ByteEnumField("extprotocolid", 3, _EIGRP_EXTERNAL_PROTOCOL_ID),  # noqa: E501
                   FlagsField("flags", 0, 8, _EIGRP_EXTROUTE_FLAGS),
                   IntField("delay", 0),
                   IntField("bandwidth", 256000),
                   ThreeBytesField("mtu", 1500),
                   ByteField("hopcount", 1),
                   ByteField("reliability", 0),
                   ByteField("load", 1),
                   XShortField("reserved2", 0),
                   ByteField("prefixlen", 8),
                   EigrpIP6Field("dst", "::", length_from=lambda pkt: pkt.prefixlen)  # noqa: E501
                   ]


_eigrp_tlv_cls = {
    0x0001: "EIGRPParam",
    0x0002: "EIGRPAuthData",
    0x0003: "EIGRPSeq",
    0x0004: "EIGRPSwVer",
    0x0005: "EIGRPNms",
    0x0006: "EIGRPStub",
    0x0102: "EIGRPIntRoute",
    0x0103: "EIGRPExtRoute",
    0x0402: "EIGRPv6IntRoute",
    0x0403: "EIGRPv6ExtRoute"
}


def _EIGRPGuessPayloadClass(p, **kargs):
    cls = conf.raw_layer
    if len(p) >= 2:
        t = struct.unpack("!H", p[:2])[0]
        clsname = _eigrp_tlv_cls.get(t, "EIGRPGeneric")
        cls = globals()[clsname]
    return cls(p, **kargs)


_EIGRP_OPCODES = {1: "Update",
                  2: "Request",
                  3: "Query",
                  4: "Replay",
                  5: "Hello",
                  6: "IPX SAP",
                  10: "SIA Query",
                  11: "SIA Reply"}

# The Conditional Receive bit is used for reliable multicast communication.
# Update-Flag: Not sure if Cisco calls it that way, but it's set when neighbors
# are exchanging routing information
_EIGRP_FLAGS = ["init", "cond-recv", "unknown", "update"]


class EIGRP(Packet):
    name = "EIGRP"
    fields_desc = [ByteField("ver", 2),
                   ByteEnumField("opcode", 5, _EIGRP_OPCODES),
                   XShortField("chksum", None),
                   FlagsField("flags", 0, 32, _EIGRP_FLAGS),
                   IntField("seq", 0),
                   IntField("ack", 0),
                   IntField("asn", 100),
                   PacketListField("tlvlist", [], _EIGRPGuessPayloadClass)
                   ]

    def post_build(self, p, pay):
        p += pay
        if self.chksum is None:
            c = checksum(p)
            p = p[:2] + chb((c >> 8) & 0xff) + chb(c & 0xff) + p[4:]
        return p

    def mysummary(self):
        summarystr = "EIGRP (AS=%EIGRP.asn% Opcode=%EIGRP.opcode%"
        if self.opcode == 5 and self.ack != 0:
            summarystr += " (ACK)"
        if self.flags != 0:
            summarystr += " Flags=%EIGRP.flags%"

        return self.sprintf(summarystr + ")")


bind_layers(IP, EIGRP, proto=88)
bind_layers(IPv6, EIGRP, nh=88)