def _buildEcho(req):
if not isinstance(req, Icmp):
req = base.extract(req, Icmp)
if req is None:
return None
resp = Icmp()
resp.type = TYPE_ECHO_REPLY
resp.code = req.code
resp.set_payload(req.next)
resp.csum = 0
resp.csum = computeChecksum(resp.pack(), 0)
return resp
def buildArpResponse(packet, mac):
if not isinstance(packet, Arp):
packet = base.extract(packet, Arp)
if packet is None:
return None
resp = Arp()
resp.hwdst = packet.hwsrc
resp.protodst = packet.protosrc
resp.hwsrc = mac
resp.protosrc = packet.protodst
resp.hwtype = Arp.HW_TYPE_ETHERNET
resp.hwlen = 6
resp.prototype = Arp.PROTO_TYPE_IP
resp.protolen = 4
resp.opcode = Arp.REPLY
return resp
def checksum(pkt):
icmpPkt = base.extract(pkt, Icmp)
if not icmpPkt:
return 0
s = icmpPkt.hdr()
h = icmpPkt.next
while h is not None:
m = getattr(h, "hdr", None)
if m is None:
s = "%s%s" % (s, str(h))
break
s = "%s%s" % (s, h.hdr())
m = getattr(h, "next", None)
if m is None:
break
h = m
return computeChecksum(s, 0)
def extract(packet):
ipPkt = base.extract(packet, Ipv4)
if ipPkt is None:
return None
return ipPkt
def extract(packet):
tcpPkt = base.extract(packet, Tcp)
return tcpPkt
def extractReply(packet):
dhcpPkt = base.extract(packet, Dhcp)
if dhcpPkt is None:
return None
return extract(dhcpPkt, Dhcp.BOOTREPLY)
def extractRequest(packet):
dhcpPkt = base.extract(packet, Dhcp)
if dhcpPkt is None:
return None
return extract(dhcpPkt, Dhcp.BOOTREQUEST)
def extractResponse(packet):
icmpPkt = base.extract(packet, Icmp)
if icmpPkt is None:
return None
return extract(icmpPkt, TYPE_ECHO_REPLY)
def extractRequest(packet):
icmpPkt = base.extract(packet, Icmp)
return extract(icmpPkt, TYPE_ECHO_REQUEST)
def extract(packet):
udpPkt = base.extract(packet, Udp)
return udpPkt
def extract(packet):
pkt = base.extract(packet, Ethernet)
return pkt
def extract(packet):
arpPkt = base.extract(packet, Arp)
if arpPkt is None:
return None
return arpPkt
def extractResponse(packet):
arpPkt = base.extract(packet, Arp)
if arpPkt is None:
return None
return extractTyp(Arp.REPLY, arpPkt)
def extractRequest(packet):
arpPkt = base.extract(packet, Arp)
return extractTyp(Arp.REQUEST, arpPkt)
