| #! /usr/bin/env python |
| |
| # 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/>. |
| |
| # scapy.contrib.description = IGMP/IGMPv2 |
| # scapy.contrib.status = loads |
| |
| from __future__ import print_function |
| from scapy.packet import * |
| from scapy.fields import * |
| from scapy.layers.inet import * |
| from scapy.layers.l2 import DestMACField, getmacbyip |
| from scapy.error import warning |
| from scapy.compat import chb, orb |
| |
| 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" |
| underlayer = self.underlayer |
| if not self.type in [0x11, 0x30]: # General Rule 1 |
| 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 |
| elif isValidMCAddr(gaddr): |
| underlayer.dst = gaddr # IP rule 3a |
| 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 |
| elif ((self.type == 0x12) or (self.type == 0x16)) and (isValidMCAddr(gaddr)): |
| underlayer.dst = gaddr # IP rule 3b |
| else: |
| warning("Invalid IGMP Type detected !") |
| return False |
| if not any(isinstance(x, IPOption_Router_Alert) for x in underlayer.options): |
| 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 |
| 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%") |
| else: |
| return self.sprintf("IGMP %IGMP.type% %IGMP.gaddr%") |
| |
| bind_layers( IP, IGMP, frag=0, |
| proto=2, |
| ttl=1) |
