50行Python代码输出各种网络协议报文结构的纯文本表格图

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

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#!/usr/bin/env python

# -*- coding: utf-8 -*-

'''''

Copyright (c) 2014, Thomas Hu. All rights reserved.

Created on 2014-8-3

@author: Thomas Hu

@email : thomashtq#163.com

'''

import math

from string import ljust, rjust, center

def format_protocol(head_list, just_type):

just_dict = {"ljust": ljust,

"rjust": rjust,

"center": center,

}

just_func = just_dict.get(just_type.lower(), center)

vchar = "|"

head = vchar

width = 2

max_key = 0

# Get the maximum width

for item in head_list:

tmp = math.ceil(float(len(item[0])) / item[1])

if tmp > width:

width = int(tmp)

if len(item[0]) > max_key:

max_key = len(item[0])

for i in range(32):

head += " "*(width - len(str(i))) + str(i) + vchar

hline = vchar + "-" *(len(head) - 2) + vchar

print(head)

print(hline)

index = 0

line = vchar

# Print protocol head

for item in head_list:

line += item[0].center(item[1] * (width + 1) - 1, " ") + vchar

index += item[1]

if index % 32 == 0:

print(line)

print(hline)

line = vchar

# Print protocol description

print("\r\nThe protocol head items description are as follows:")

for item in head_list:

print("%s : %s"%(just_func(item[0], max_key, " "), item[2]))

if __name__ == '__main__':

head_list = [("Ver", 4, "Protocol version"),

("Head", 4, "Head length(in bytes)"),

("TOS", 8, "Type of service"),

("Total Length", 16, "The total length of IP packet(in bytes)"),

("ID", 16, "The identification of packet"),

("Flag", 3, "The flag"),

("Offset", 13, "The offset"),

("TTL", 8, "Time to live"),

("Proto", 8, "The protocol id"),

("Checksum", 16, "The head check sum"),

("Source Address", 32, "The source IP address"),

("Destination Address", 32, "The destination IP address"),

("Opitons(if has)", 32, "The options block, if has that"),

("Data", 32, "The data block of IP packet"),

]

format_protocol(head_list, "ljust")

输出结果