#! /usr/bin/env python2

# This file is part of Scapy
# Scapy is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# any later version.
#
# Scapy is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Scapy. If not, see <http://www.gnu.org/licenses/>.

# flake8: noqa: E501

# scapy.contrib.description = Internet Group Management Protocol v1/v2 (IGMP/IGMPv2)
# scapy.contrib.status = loads

from __future__ import print_function
from scapy.compat import chb, orb
from scapy.error import warning
from scapy.fields import ByteEnumField, ByteField, IPField, XShortField
from scapy.layers.inet import IP, IPOption_Router_Alert
from scapy.layers.l2 import Ether, getmacbyip
from scapy.packet import bind_layers, Packet
from scapy.utils import atol, checksum


def isValidMCAddr(ip):
    """convert dotted quad string to long and check the first octet"""
    FirstOct = atol(ip) >> 24 & 0xFF
    return (FirstOct >= 224) and (FirstOct <= 239)


class IGMP(Packet):
    """IGMP Message Class for v1 and v2.

This class is derived from class Packet. You  need call "igmpize()"
so the packet is transformed according the RFC when sent.
a=Ether(src="00:01:02:03:04:05")
b=IP(src="1.2.3.4")
c=IGMP(type=0x12, gaddr="224.2.3.4")
x = a/b/c
x[IGMP].igmpize()
sendp(a/b/c, iface="en0")

    Parameters:
      type    IGMP type field, 0x11, 0x12, 0x16 or 0x17
      mrcode  Maximum Response time (zero for v1)
      gaddr   Multicast Group Address 224.x.x.x/4

See RFC2236, Section 2. Introduction for definitions of proper
IGMPv2 message format   http://www.faqs.org/rfcs/rfc2236.html

  """
    name = "IGMP"

    igmptypes = {0x11: "Group Membership Query",
                 0x12: "Version 1 - Membership Report",
                 0x16: "Version 2 - Membership Report",
                 0x17: "Leave Group"}

    fields_desc = [ByteEnumField("type", 0x11, igmptypes),
                   ByteField("mrcode", 20),
                   XShortField("chksum", None),
                   IPField("gaddr", "0.0.0.0")]

    def post_build(self, p, pay):
        """Called implicitly before a packet is sent to compute and place IGMP checksum.

        Parameters:
          self    The instantiation of an IGMP class
          p       The IGMP message in hex in network byte order
          pay     Additional payload for the IGMP message
        """
        p += pay
        if self.chksum is None:
            ck = checksum(p)
            p = p[:2] + chb(ck >> 8) + chb(ck & 0xff) + p[4:]
        return p

    @classmethod
    def dispatch_hook(cls, _pkt=None, *args, **kargs):
        if _pkt and len(_pkt) >= 4:
            from scapy.contrib.igmpv3 import IGMPv3
            if orb(_pkt[0]) in [0x22, 0x30, 0x31, 0x32]:
                return IGMPv3
            if orb(_pkt[0]) == 0x11 and len(_pkt) >= 12:
                return IGMPv3
        return IGMP

    def igmpize(self):
        """Called to explicitly fixup the packet according to the IGMP RFC

        The rules are:
        General:
            1.  the Max Response time is meaningful only in Membership Queries and should be zero
        IP:
            1. Send General Group Query to 224.0.0.1 (all systems)
            2. Send Leave Group to 224.0.0.2 (all routers)
            3a.Otherwise send the packet to the group address
            3b.Send reports/joins to the group address
            4. ttl = 1 (RFC 2236, section 2)
            5. send the packet with the router alert IP option (RFC 2236, section 2)
        Ether:
            1. Recalculate destination

        Returns:
            True    The tuple ether/ip/self passed all check and represents
                    a proper IGMP packet.
            False   One of more validation checks failed and no fields
                    were adjusted.

        The function will examine the IGMP message to assure proper format.
        Corrections will be attempted if possible. The IP header is then properly
        adjusted to ensure correct formatting and assignment. The Ethernet header
        is then adjusted to the proper IGMP packet format.
        """
        gaddr = self.gaddr if hasattr(self, "gaddr") and self.gaddr else "0.0.0.0"  # noqa: E501
        underlayer = self.underlayer
        if self.type not in [0x11, 0x30]:                               # General Rule 1  # noqa: E501
            self.mrcode = 0
        if isinstance(underlayer, IP):
            if (self.type == 0x11):
                if (gaddr == "0.0.0.0"):
                    underlayer.dst = "224.0.0.1"                        # IP rule 1  # noqa: E501
                elif isValidMCAddr(gaddr):
                    underlayer.dst = gaddr                              # IP rule 3a  # noqa: E501
                else:
                    warning("Invalid IGMP Group Address detected !")
                    return False
            elif ((self.type == 0x17) and isValidMCAddr(gaddr)):
                underlayer.dst = "224.0.0.2"                           # IP rule 2  # noqa: E501
            elif ((self.type == 0x12) or (self.type == 0x16)) and (isValidMCAddr(gaddr)):  # noqa: E501
                underlayer.dst = gaddr                                 # IP rule 3b  # noqa: E501
            else:
                warning("Invalid IGMP Type detected !")
                return False
            if not any(isinstance(x, IPOption_Router_Alert) for x in underlayer.options):  # noqa: E501
                underlayer.options.append(IPOption_Router_Alert())
            _root = self.firstlayer()
            if _root.haslayer(Ether):
                # Force recalculate Ether dst
                _root[Ether].dst = getmacbyip(underlayer.dst)          # Ether rule 1  # noqa: E501
        from scapy.contrib.igmpv3 import IGMPv3
        if isinstance(self, IGMPv3):
            self.encode_maxrespcode()
        return True

    def mysummary(self):
        """Display a summary of the IGMP object."""
        if isinstance(self.underlayer, IP):
            return self.underlayer.sprintf("IGMP: %IP.src% > %IP.dst% %IGMP.type% %IGMP.gaddr%")  # noqa: E501
        else:
            return self.sprintf("IGMP %IGMP.type% %IGMP.gaddr%")


bind_layers(IP, IGMP, frag=0,
            proto=2,
            ttl=1)
