def __calc_udp_csum(saddr, daddr, udp_data, is_ipv6=False):
size = len(udp_data)
seq = [
saddr,
daddr,
b'\x00\x11',
utils.number2bytes(size, 2),
udp_data,
]
if is_ipv6:
size += 24
else:
size += 12
if 0 != size % 2:
seq.append(b"\0")
size += 1
data = b"".join(seq)
csum = socket.htons(fn_utils.calc_csum(data, size))
# csum = __calc_checksum(data, size)
# import socket
# print(csum,socket.htons(csum_t))
if csum == 0: return 0xffff
return csum
def __calc_udp_csum(saddr, daddr, udp_data, is_ipv6=False):
size = len(udp_data)
seq = [
saddr, daddr, b'\x00\x11',
utils.number2bytes(size, 2),
udp_data,
]
if is_ipv6:
size += 24
else:
size += 12
if 0 != size % 2:
seq.append(b"\0")
size += 1
data = b"".join(seq)
csum = socket.htons(fn_utils.calc_csum(data, size))
# csum = __calc_checksum(data, size)
# import socket
# print(csum,socket.htons(csum_t))
if csum == 0: return 0xffff
return csum
def fill_ip_hdr_checksum(pkt_list):
"""填充IP包头校检和
:param pkt: 列表形式的IP数据包,比如[11,23,...]
:return:
"""
hdr_len = (pkt_list[0] & 0x0f) * 4
checksum = fn_utils.calc_csum(bytes(pkt_list), hdr_len)
pkt_list[10:12] = (
(checksum & 0xff00) >> 8,
checksum & 0x00ff,
)
return
def fill_ip_hdr_checksum(pkt_list):
"""填充IP包头校检和
:param pkt: 列表形式的IP数据包,比如[11,23,...]
:return:
"""
hdr_len = (pkt_list[0] & 0x0f) * 4
checksum = fn_utils.calc_csum(bytes(pkt_list), hdr_len)
pkt_list[10:12] = (
(checksum & 0xff00) >> 8,
checksum & 0x00ff,
)
return
def build_udp_packets(saddr,
daddr,
sport,
dport,
message,
mtu=1500,
is_udplite=False,
is_ipv6=False):
"""构建UDP数据包"""
if mtu > 1500 or mtu < 576: raise ValueError("the value of mtu is wrong!")
msg_len = 8 + len(message)
# 构建UDP数据头
udp_hdr = [
(sport & 0xff00) >> 8,
sport & 0x00ff,
(dport & 0xff00) >> 8,
dport & 0x00ff,
]
if is_udplite:
udp_hdr += [
0,
8,
0,
0,
]
csum = fn_utils.calc_csum(bytes(udp_hdr))
udp_hdr[6] = (csum & 0xff00) >> 8
udp_hdr[7] = csum & 0xff
else:
udp_hdr += [
(msg_len & 0xff00) >> 8,
msg_len & 0x00ff,
0,
0,
]
if not is_udplite:
csum = __calc_udp_csum(saddr,
daddr,
b"".join([bytes(udp_hdr), message]),
is_ipv6=is_ipv6)
udp_hdr[6] = (csum & 0xff00) >> 8
udp_hdr[7] = csum & 0xff
pkt_data = b"".join((
bytes(udp_hdr),
message,
))
if not is_ipv6:
pkt_id = random.randint(1, 65535)
else:
pkt_id = random.randint(1, 0xffffffff)
flow_label = random.randint(1, 0x0fffff)
pkts = []
flags_df = 1
if is_udplite:
p = 136
else:
p = 17
if is_ipv6 and mtu - 40 <= msg_len:
ipv6hdr = __build_ipv6_hdr(flow_label, msg_len, p, 128, saddr, daddr)
ip6data = b"".join([
ipv6hdr,
message,
])
return [
ip6data,
]
if is_ipv6:
# IPV6分包在扩展头提供,因此要算成48
ip_hdr_size = 48
else:
ip_hdr_size = 20
step = mtu - ip_hdr_size - (mtu - ip_hdr_size) % 8
b = 0
e = step
# pkt_id = 1
n = 0
every_offset = int(step / 8)
while 1:
bdata = pkt_data[b:e]
slice_size = len(bdata)
if e >= msg_len:
finish = True
else:
finish = False
if finish:
flags_mf = 0
else:
flags_mf = 1
offset = n * every_offset
if not is_ipv6:
ippkt = build_ip_packet(slice_size + 20,
p,
saddr,
daddr,
bdata,
pkt_id=pkt_id,
flags_df=flags_df,
flags_mf=flags_mf,
offset=offset)
else:
ipv6hdr = __build_ipv6_hdr(flow_label, slice_size, 44, 128, saddr,
daddr)
frag_hdr = __build_ipv6_fragment_hdr(p, offset, flags_mf, pkt_id)
ippkt = b"".join([
ipv6hdr,
frag_hdr,
bdata,
])
pkts.append(ippkt)
if finish: break
n += 1
b = e
e = b + step
return pkts
def build_udp_packets(saddr, daddr, sport, dport, message, mtu=1500, is_udplite=False, is_ipv6=False):
"""构建UDP数据包"""
if mtu > 1500 or mtu < 576: raise ValueError("the value of mtu is wrong!")
msg_len = 8 + len(message)
# 构建UDP数据头
udp_hdr = [
(sport & 0xff00) >> 8,
sport & 0x00ff,
(dport & 0xff00) >> 8,
dport & 0x00ff,
]
if is_udplite:
udp_hdr += [
0, 8,
0, 0,
]
csum = fn_utils.calc_csum(bytes(udp_hdr))
udp_hdr[6] = (csum & 0xff00) >> 8
udp_hdr[7] = csum & 0xff
else:
udp_hdr += [
(msg_len & 0xff00) >> 8,
msg_len & 0x00ff,
0, 0,
]
if not is_udplite:
csum = __calc_udp_csum(saddr, daddr,
b"".join([bytes(udp_hdr), message]),
is_ipv6=is_ipv6)
udp_hdr[6] = (csum & 0xff00) >> 8
udp_hdr[7] = csum & 0xff
pkt_data = b"".join(
(bytes(udp_hdr), message,)
)
if not is_ipv6:
pkt_id = random.randint(1, 65535)
else:
pkt_id = random.randint(1, 0xffffffff)
flow_label = random.randint(1, 0x0fffff)
pkts = []
flags_df = 1
if is_udplite:
p = 136
else:
p = 17
if is_ipv6 and mtu - 40 <= msg_len:
ipv6hdr = __build_ipv6_hdr(flow_label, msg_len, p, 128, saddr, daddr)
ip6data = b"".join([ipv6hdr, message, ])
return [ip6data, ]
if is_ipv6:
# IPV6分包在扩展头提供,因此要算成48
ip_hdr_size = 48
else:
ip_hdr_size = 20
step = mtu - ip_hdr_size - (mtu - ip_hdr_size) % 8
b = 0
e = step
# pkt_id = 1
n = 0
every_offset = int(step / 8)
while 1:
bdata = pkt_data[b:e]
slice_size = len(bdata)
if e >= msg_len:
finish = True
else:
finish = False
if finish:
flags_mf = 0
else:
flags_mf = 1
offset = n * every_offset
if not is_ipv6:
ippkt = build_ip_packet(slice_size + 20, p,
saddr, daddr, bdata, pkt_id=pkt_id,
flags_df=flags_df, flags_mf=flags_mf,
offset=offset
)
else:
ipv6hdr = __build_ipv6_hdr(flow_label, slice_size, 44, 128, saddr, daddr)
frag_hdr = __build_ipv6_fragment_hdr(p, offset, flags_mf, pkt_id)
ippkt = b"".join([ipv6hdr, frag_hdr, bdata, ])
pkts.append(ippkt)
if finish: break
n += 1
b = e
e = b + step
return pkts