Python:用Python实现Bencode解码
最近了解了一下Bencode编码和解码，就用Python试着写了个Bencode解码的代码。BEncoding是BitTorrent用在传输数据结构的编码方式，这种编码方式支持四种类型的数据：string, int, Dictionary<string, object>, List<object>，各自的编码规则如下：
[*]string类型的编码格式为:。以字符串的长度开头，加一个冒号，并以字符串内容结束。示例："abc" => 3:abc
[*]int类型的编码格式为ie。以i开头，加上数字，以e结尾。 示例：123 => i123e
[*]List<object>类型的编码格式为le。以l开头，加上列表中各个元素的编码（元素的类型同样为BEncoding支持的类型），以e结尾。 示例：List<"abc", 123> => l3:abci123ee
[*]Dictionary<string, object>类型的编码格式为de。以d开头，加上字典中每个键值对的编码，以e结尾。示例：Dictionary<{"name":"create chen"},{"age":23}> => d4:name11:create chen3:agei23ee
代码如下：
# 解析List<object>类型，例：l3:abci123ee => List<"abc", 123>
def decode_list(str,p):
l = len(str)
# print(l)
# print(p)
list = []
while p < l:
if str.isdigit():
f_m = str.index(":",p + 1,l)
f_n = int(str)
f_e = f_m + f_n
data_str = str
list.append(data_str)
p = f_e
elif str == "i":
end = str.index("e", p + 1, l)
data_int = str
list.append(data_int)
p = end
elif str == "e":
p = p + 2
list.append("p")
list.append(p)
break
elif str == "l":
p = p + 1
return list
# 解析Dictionary<string, object>类型，例：d4:name11:create chen3:agei23ee => Dictionary<{"name":"create chen"},{"age":23}>
def decode_dict(str,p):
test = decode_list(str,p)
data_seq = []
data_val = []
i = 0
while i < len(test):
data_seq.append(test)
data_val.append(test)
i = i + 2
data_dict = dict.fromkeys(data_seq)
i = 0
while i < len(test) / 2:
data_dict] = data_val
i = i + 1
return data_dict
data = "d4:name11:create chen3:agei23eel3:abci123eei23e3:age"
print(data)
# 定义全局指针，追踪所查位置
global p
l = len(data)
p = 0
while p < l:
# 判断是否为dict型
if data == "d":
data_dict = decode_dict(data,p)
p = int(data_dict["p"])
del data_dict["p"]
print(data_dict)
f = open("text.txt","a+")
for k, v in data_dict.items():
f.write(k + ":" + str(v))
f.write("\n")
f.close()
# 判断是否为list型
elif data == "l":
data_list = decode_list(data,p)
p = int(data_list[-1])
del data_list[-1]
del data_list[-1]
print(data_list)
f = open("text.txt", "a+")
for i in data_list:
f.write(i)
f.write("\n")
f.close()
# 判断是否为str型，解析
elif data == "i":
f = data.index("e",p,l)
data_int = data
p = f + 1
print(data_int)
f = open("text.txt", "a+")
f.write(data_int)
f.write("\n")
f.close()
# 判断是否为int型，解析（为了方便，暂未将其结果转为int型，而是str型，例：“123”
elif data.isdigit():
f = data.index(":",p,l)
print(data)
data_str = data) + f + 1]
print(data_str)
p = int(data) + f + 1
f = open("text.txt", "a+")
f.write(data_str)
f.write("\n")
f.close()
print("It's done")、
谢谢，刚好在弄这块 代码看的有点头晕，不过支持一下 {:1_921:}
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