def option(self):
"""分析tcp的可选项字段(分析了常用字段)"""
size = len(self._option)
ret = []
if size > 0:
option = self._option
while size > 0:
if option[0] == 0x00:
ret.append({"END": option[0]})
break
if option[0] == 0x01:
ret.append({"NOP": option[0]})
size -= 1
option = option[1:]
elif option[0] == 0x02:
# MSS
ret.append({
"MSS": {
"length": option[1],
"value": BytesOrder.bytes2int(option[2:4], "big")
}
})
size -= 4
option = option[4:]
elif option[0] == 0x03:
# 窗口扩大因子
ret.append({
"WSALE": {
"length": option[1],
"shift_count": option[2]
}
})
size -= 3
option = option[3:]
elif option[0] == 0x04:
# SACK
ret.append({"SACK": {"length": option[1]}})
size -= 2
option = option[2:]
elif option[0] == 0x08:
# 时间戳
ret.append({
"TIMESTAMP": {
"length": option[1],
"value": BytesOrder.bytes2int(option[2:6], "big"),
"repl_value":
BytesOrder.bytes2int(option[6:10], "big")
}
})
size -= 10
option = option[10:]
else:
break
else:
ret = None
return ret
def signature(data):
"""验证签名同时确定排序,虽然还无法读取到大小端但不影响"""
sig = BytesOrder.bytes2int(data)
if sig == 0xa1b2c3d4:
BytesOrder.order = "big"
return True
elif sig == 0xd4c3b2a1:
BytesOrder.order = "little"
return True
return False
def __init__(self, data):
assert len(data) == 24
self._magic_number = data[:4]
if PcapHead.signature(self._magic_number) is False:
raise Exception("不支持的文件格式")
self._version_major = BytesOrder.bytes2int(data[4:6])
self._version_minor = BytesOrder.bytes2int(data[6:8])
self._thiszone = BytesOrder.bytes2int(data[8:12])
self._sigfigs = BytesOrder.bytes2int(data[12:16])
self._snaplen = BytesOrder.bytes2int(data[16:20])
self._link_type = BytesOrder.bytes2int(data[20:24])
def header_len(self):
return BytesOrder.bytes2int(self._header_len, "big")
def dst(self):
return BytesOrder.bytes2int(self._dst, "big")
def src(self):
return BytesOrder.bytes2int(self._src, "big")
def total_len(self):
return BytesOrder.bytes2int(self._total_len, "big")
def id(self):
"""IP序号"""
return BytesOrder.bytes2int(self._id, "big")
def __init__(self, data):
self._ts_sec = BytesOrder.bytes2int(data[:4])
self._ts_usec = BytesOrder.bytes2int(data[4:8])
self._incl_len = BytesOrder.bytes2int(data[8:12])
self._orig_len = BytesOrder.bytes2int(data[12:16])
def operate(self):
return BytesOrder.bytes2int(self._operate, "big")
def urqt_p(self):
"""获取紧急指针"""
return BytesOrder.bytes2int(self._urqt_p, "big")
def wnd_size(self):
"""获取滑动窗口大小"""
return BytesOrder.bytes2int(self._wnd_size, "big")
def ack(self):
"""获取确认号"""
return BytesOrder.bytes2int(self._ack_no, "big")
def seq(self):
"""获取序列号"""
return BytesOrder.bytes2int(self._seq_no, "big")