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.
"""
from scapy.contrib.igmpv3 import IGMPv3
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
elif (self.type in [0x11, 0x22, 0x30, 0x31, 0x32] and isinstance(self, IGMPv3)):
pass
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())
underlayer.ttl = 1 # IP rule 4
_root = self.firstlayer()
if _root.haslayer(Ether):
# Force recalculate Ether dst
_root[Ether].dst = getmacbyip(underlayer.dst) # Ether rule 1 # noqa: E501
if isinstance(self, IGMPv3):
self.encode_maxrespcode()
return True
def fixup(pkt):
"""Fixes up the underlying IP() and Ether() headers."""
assert pkt.haslayer(IGMPv3), \
"This packet is not an IGMPv4 packet; cannot fix it up"
igmp = pkt.getlayer(IGMPv3)
if pkt.haslayer(IP):
ip = pkt.getlayer(IP)
ip.ttl = 1
ip.proto = 2
ip.tos = 0xc0
ip.options = [IPOption_Router_Alert()]
if igmp.type == IGMP_TYPE_MEMBERSHIP_QUERY:
if igmp.gaddr == "0.0.0.0":
ip.dst = "224.0.0.1"
else:
assert IGMPv3.is_valid_mcaddr(igmp.gaddr), \
"IGMP membership query with invalid mcast address"
ip.dst = igmp.gaddr
elif igmp.type == IGMP_TYPE_V2_LEAVE_GROUP and \
IGMPv3.is_valid_mcaddr(igmp.gaddr):
ip.dst = "224.0.0.2"
elif igmp.type in (IGMP_TYPE_V1_MEMBERSHIP_REPORT,
IGMP_TYPE_V2_MEMBERSHIP_REPORT) and \
IGMPv3.is_valid_mcaddr(igmp.gaddr):
ip.dst = igmp.gaddr
# We do not need to fixup the ether layer, it is done by scapy
#
# if pkt.haslayer(Ether):
# eth = pkt.getlayer(Ether)
# ip_long = atol(ip.dst)
# ether.dst = '01:00:5e:%02x:%02x:%02x' % (
# (ip_long >> 16) & 0x7f, (ip_long >> 8) & 0xff,
# ip_long & 0xff )
return pkt