def buildUdpResponse(req, packet, **kwargs):
reqUdp = req.find(name)
if reqUdp is None:
return None
resp = Udp()
resp.srcport = reqUdp.dstport
resp.dstport = reqUdp.srcport
if isinstance(packet, str):
resp.len += len(packet)
else:
resp.len += len(packet.hdr(packet.payload))
resp.set_payload(packet)
return resp
def buildRequest(src, dst, payload='', ipId=0):
udpPkt = Udp()
udpPkt.srcport = src[2]
udpPkt.dstport = dst[2]
if isinstance(payload, str):
udpPkt.len += len(payload)
else:
udpPkt.len += len(payload.hdr())
udpPkt.set_payload(payload)
udpPkt.parsed = True
ipPkt = Ipv4()
ipPkt.flags = Ipv4.DF_FLAG
ipPkt.srcip = src[1]
ipPkt.dstip = dst[1]
ipPkt.id = ipId
ipPkt.protocol = Ipv4.UDP_PROTOCOL
ipPkt.set_payload(udpPkt)
ipPkt.iplen += udpPkt.len
ipPkt.parsed = True
udpPkt.csum = checksum(udpPkt)
ethPkt = Ethernet()
ethPkt.src = src[0]
ethPkt.dst = dst[0]
ethPkt.type = Ethernet.IP_TYPE
ethPkt.set_payload(ipPkt)
ethPkt.parsed = True
return ethPkt
def checksum(packet):
if not isinstance(packet, Udp):
packet = extract(packet)
if packet is None:
return 0
if packet.__dict__.has_key('arr'):
return packet.checksum()
udpHdr = packet.hdr(packet.payload)
if packet.next is None:
nextHdr = ''
elif isinstance(packet.next, str):
nextHdr = packet.next
else:
nextHdr = packet.next.hdr('')
s = '%s%s' % (udpHdr, nextHdr)
udpPkt = Udp(raw=s, prev=packet.prev)
udpPkt.next = nextHdr
return udpPkt.checksum()
