经常与TCP/IP协议族打交道，免不了要画各种协议报文的纯文本结构图。为何需要纯文本结构图？想想在工程的源代码中，您能贴张jpeg或png的图片上去？
示范代码以输出 IP 包头为例， 使用python 2.7 编写（Python 3 应该也能运行）。本程序还可以用来画类似结构的表格图，再次抛砖引玉，欢迎大家使用交流。
代码
[python] view plaincopy
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#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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'''''
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Copyright (c) 2014, Thomas Hu. All rights reserved.
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Created on 2014-8-3
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@author: Thomas Hu
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@email : thomashtq#163.com
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'''
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import math
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from string import ljust, rjust, center
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def format_protocol(head_list, just_type):
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just_dict = {"ljust": ljust,
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"rjust": rjust,
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"center": center,
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}
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just_func = just_dict.get(just_type.lower(), center)
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vchar = "|"
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head = vchar
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width = 2
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max_key = 0
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# Get the maximum width
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for item in head_list:
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tmp = math.ceil(float(len(item[0])) / item[1])
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if tmp > width:
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width = int(tmp)
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if len(item[0]) > max_key:
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max_key = len(item[0])
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for i in range(32):
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head += " "*(width - len(str(i))) + str(i) + vchar
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hline = vchar + "-" *(len(head) - 2) + vchar
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print(head)
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print(hline)
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index = 0
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line = vchar
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# Print protocol head
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for item in head_list:
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line += item[0].center(item[1] * (width + 1) - 1, " ") + vchar
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index += item[1]
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if index % 32 == 0:
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print(line)
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print(hline)
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line = vchar
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# Print protocol description
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print("\r\nThe protocol head items description are as follows:")
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for item in head_list:
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print("%s : %s"%(just_func(item[0], max_key, " "), item[2]))
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if __name__ == '__main__':
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head_list = [("Ver", 4, "Protocol version"),
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("Head", 4, "Head length(in bytes)"),
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("TOS", 8, "Type of service"),
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("Total Length", 16, "The total length of IP packet(in bytes)"),
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("ID", 16, "The identification of packet"),
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("Flag", 3, "The flag"),
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("Offset", 13, "The offset"),
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("TTL", 8, "Time to live"),
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("Proto", 8, "The protocol id"),
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("Checksum", 16, "The head check sum"),
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("Source Address", 32, "The source IP address"),
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("Destination Address", 32, "The destination IP address"),
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("Opitons(if has)", 32, "The options block, if has that"),
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("Data", 32, "The data block of IP packet"),
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]
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format_protocol(head_list, "ljust")
输出结果