如何切片十六进制数据？

Question

我有和十六进制数据，其中有三个数据，我可以将十六进制数据中包含的信息分开：

1. ID（2字节）
2. 数据包的长度（2字节）
3. 信息

例如，通过数据包的长度，我们可以知道这个十六进制数据中的数据有多长 十六进制数据=0001001447364B5F48312E305F56312E3165000300133863339323130333433333373100040008383036340000200154D41A3258584D524A32444A36313590005000501000084341524400070009434152480005000018393931303231383535353834300D000A000E706F7274616C6D673

如果我们根据上述信息手动分离此十六进制数据，则我们将获得此数据 0001001447364B5F48312E305F56312E312E3165

这里

id=0001

数据包长度=0014=20

信息=47364B5F48312E305F56312E312E3165

我试图用我的代码来分离信息，但它只分离第一个数据，我想分离整个十六进制数据

这是我的python代码：

data="0001001447364B5F48312E305F56312E312E316500030013383633393231303334333034333731"
t=data[0:4]
l=data[4:8]
hex_to_decimal=int(l, 16)
data1=data[0:hex_to_decimal*2]
print(data1)

有人能帮我弄清楚吗

Answer 1

您可以在data字符串上循环并提取数据

下面是它的样子：

data="0001001447364B5F48312E305F56312E312E3165000300133836333932313033343330343337310004000838303634000200154D414A3258584D524A32444A363135303900050005010006000843415244000700094341524431000800050000090018383939313035323138303935393533303834300D000A000E706F7274616C6E6D6D73"

i = 0
while i < len(data):
    t = data[i:i+4]
    l = data[i+4:i+8]
    hex_to_decimal = int(l, 16)
    data1 = data[i:i+hex_to_decimal*2]

    print(f'Length: {hex_to_decimal*2}\nData: {data1}\n')
    i += hex_to_decimal*2
    

Output:

Length: 40
Data: 0001001447364B5F48312E305F56312E312E3165

Length: 38
Data: 00030013383633393231303334333034333731

Length: 16
Data: 0004000838303634

Length: 42
Data: 000200154D414A3258584D524A32444A3631353039

Length: 10
Data: 0005000501

Length: 16
Data: 0006000843415244

Length: 18
Data: 000700094341524431

Length: 10
Data: 0008000500

Length: 48
Data: 00090018383939313035323138303935393533303834300D

Length: 28
Data: 000A000E706F7274616C6E6D6D73

Answer 2

这就是struct包的真正用途（以及bytes.fromhex）

>>> import struct
>>> s = "0001001447364B5F48312E305F56312E312E3165000300133836333932313033343330343337310004000838303634000200154D414A3258584D524A32444A363135303900050005010006000843415244000700094341524431000800050000090018383939313035323138303935393533303834300D000A000E706F7274616C6E6D6D73"
>>> mbytes = bytes.fromhex(s)
>>> msg_id,msg_size = struct.unpack(">hh",mbytes[:4])
# 1, 20
>>> msg_bytes = struct.unpack_from("{}s".format(msg_size),mbytes[4:])[0]
>>> msg_hex = bytes.hex(msg_bytes)
# 47364b5f48312e305f56312e312e316500030013
# which i think is what you actually want... but if you actually think size represents each character in that string you will need to make a modification
>>> alt_hex = s[8:][msg_size] 
# 47364b5f48312e305f56 ( which i think is the wrong value...)