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我使用Scapy在Python中伪造数据包，但我需要手动修改特定数据包内的一系列位（scapy不支持），所以我做了以下：from hex string to int and back
给定一个数据包p，I将其转换为十六进制字符串，然后到底座10，并最后达到二进制数。我修改了我感兴趣的位，然后我将它转换回为一个包。我有麻烦将其转换回十六进制字符串的相同的格式...
# I create a packet with Scapy
In [3]: p = IP(dst="www.google.com")/TCP(sport=10000, dport=10001)/"asdasdasd"
In [6]: p
Out[6]: <IP frag=0 proto=tcp dst=Net('www.google.com') |<TCP sport=webmin dport=10001 |<Raw load='asdasdasd' |>>>
# I convert it to a hex string
In [7]: p_str = str(p)
In [8]: p_str
Out[8]: "E\x00\x001\x00\x01\x00\[email protected]\x06Q\x1c\x86;\x81\x99\xad\xc2t\x13'\x10'\x11\x00\x00\x00\x00\x00\x00\x00\x00P\x02 \x00\x19a\x00\x00asdasdasd"
# I convert it to an integer
In [9]: p_int = int(p_str.encode('hex'), 16)
In [10]: p_int
Out[10]: 2718738542629841457617712654487115358609175161220115024628433766520503527612013312415911474170471993202533513363026788L
# Finally, I convert it to a binary number
In [11]: p_bin = bin(p_int)
In [11]: p_bin
Out[11]: '0b1000101000000000000000000110001000000000000000100000000000000000100000000000110010100010001110010000110001110111000000110011001101011011100001001110100000100110010011100010000001001110001000100000000000000000000000000000000000000000000000000000000000000000101000000000010001000000000000000011001011000010000000000000000011000010111001101100100011000010111001101100100011000010111001101100100'
# ... (I modify some bits in p_bin, for instance the last three)...
In [12]: p_bin_modified = p_bin[:-3] + '000'
# I convert it back to a packet!
# First to int
In [13]: p_int_modified = int(p_bin_modified, 2)
In [14]: p_int_modified
Out[14]: 2718738542629841457617712654487115358609175161220115024628433766520503527612013312415911474170471993202533513363026784L
# Then to a hex string
In [38]: hex(p_int_modified)
Out[38]: '0x45000031000100004006511c863b8199adc274132710271100000000000000005002200019610000617364617364617360L'
行动！它看起来不像原始十六进制字符串的格式。任何想法如何做到这一点？
编辑： 好吧，我发现decode('hex')，它工作在一个十六进制数，但它打破了整体转换的反思...
In [73]: hex(int(bin(int(str(p).encode('hex'), 16)), 2)).decode('hex')
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-73-f5b9d74d557f> in <module>()
----> 1 hex(int(bin(int(str(p).encode('hex'), 16)), 2)).decode('hex')
/usr/lib/python2.7/encodings/hex_codec.pyc in hex_decode(input, errors)
40 """
41 assert errors == 'strict'
---> 42 output = binascii.a2b_hex(input)
43 return (output, len(input))
44
TypeError: Odd-length string
EDIT2：我得到了同样的错误，如果我删除转换为二进制数...
In [13]: hex(int(str(p).encode('hex'), 16)).decode('hex')
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/home/ricky/<ipython-input-13-47ae9c87a5d2> in <module>()
----> 1 hex(int(str(p).encode('hex'), 16)).decode('hex')
/usr/lib/python2.7/encodings/hex_codec.pyc in hex_decode(input, errors)
40 """
41 assert errors == 'strict'
---> 42 output = binascii.a2b_hex(input)
43 return (output, len(input))
44
TypeError: Odd-length string
为什么使用字符串函数进行位操作？这不是很昂贵的往返？ – Hyperboreus
噢好吧，明白了。这只是一个例子。重要的是我必须通过十六进制字符串，它不会返回相同的原始值... –
我删除了转换为二进制数，但我得到了同样的错误:(我在这里错过了什么？ –