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 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)
