def udp_craft(pkt, mac, fp):
try:
ether = Ether()
ether.src = mac
ether.dst = pkt[Ether].dst
ether.type = 0x800
except IndexError:
ether = None
ip = IP()
ip.src = pkt[IP].dst
ip.dst = pkt[IP].src
ip.ttl = int(fp.probe['U1']['TTL'], 16)
ip.flags = fp.probe['U1']['DF']
ip.len = 56
ip.id = 4162
icmp = ICMP()
icmp.type = 3
icmp.unused = 0
icmp.code = 13 # code 3 for reply
iperror = IPerror()
iperror.proto = 'udp'
iperror.ttl = 0x3E
iperror.len = fp.probe['U1']['RIPL']
iperror.id = fp.probe['U1']['RID']
ripck_val = fp.probe['U1']['RIPCK']
if ripck_val == 'G':
pass
elif ripck_val == 'Z':
iperror.chksum = 0
else:
iperror.chksum = pkt[IP].chksum
udperror = UDPerror()
udperror.sport = pkt[UDP].sport
udperror.dport = pkt[UDP].dport
udperror.len = pkt[UDP].len
if fp.probe['U1']['RUCK'] == 'G':
udperror.chksum = pkt[UDP].chksum
else:
udperror.chksum = fp.probe['U1']['RUCK']
try:
ipl = int(fp.probe['U1']['IPL'], 16)
except KeyError:
ipl = None
data = pkt[Raw].load
fin_pkt = ip / icmp / iperror / udperror / data if ether is None else ether / ip / icmp / iperror / udperror / data
return fin_pkt
