def SendPacketTooBig(self, packet):
src = packet.getlayer(scapy.IPv6).src
datalen = IPV6_MIN_MTU - ICMPV6_HEADER_LEN
self.SendPacket(
scapy.IPv6(src=self.INTERMEDIATE_IPV6, dst=src) /
scapy.ICMPv6PacketTooBig(mtu=self.LINK_MTU) /
str(packet)[:datalen])
def ICMPPacketTooBig(version, srcaddr, dstaddr, packet):
if version == 4:
return ("ICMPv4 fragmentation needed",
scapy.IP(src=srcaddr, dst=dstaddr, proto=1) /
scapy.ICMPerror(type=3, code=4, unused=1280) / str(packet)[:64])
else:
udp = packet.getlayer("UDP")
udp.payload = str(udp.payload)[:1280-40-8]
return ("ICMPv6 Packet Too Big",
scapy.IPv6(src=srcaddr, dst=dstaddr) /
scapy.ICMPv6PacketTooBig() / str(packet)[:1232])
def ICMPPacketTooBig(version, srcaddr, dstaddr, packet):
if version == 4:
desc = "ICMPv4 fragmentation needed"
pkt = (scapy.IP(src=srcaddr, dst=dstaddr, proto=1) /
scapy.ICMPerror(type=3, code=4) / str(packet)[:64])
# Only newer versions of scapy understand that since RFC 1191, the last two
# bytes of a fragmentation needed ICMP error contain the MTU.
if hasattr(scapy.ICMP, "nexthopmtu"):
pkt[scapy.ICMPerror].nexthopmtu = PTB_MTU
else:
pkt[scapy.ICMPerror].unused = PTB_MTU
return desc, pkt
else:
return ("ICMPv6 Packet Too Big", scapy.IPv6(src=srcaddr, dst=dstaddr) /
scapy.ICMPv6PacketTooBig(mtu=PTB_MTU) / str(packet)[:1232])