1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
# bencode structured encoding
#
# Written by Petru Paler
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# Modifications copyright (C) 2008 Canonical Ltd
# Modifications copyright (C) 2021-2023 Jelmer Vernooij
from typing import Callable, Dict, List, Type
class BDecoder:
def __init__(self, yield_tuples=False, bytestring_encoding=None) -> None:
"""Constructor.
:param yield_tuples: if true, decode "l" elements as tuples rather than
lists.
"""
self.yield_tuples = yield_tuples
self.bytestring_encoding = bytestring_encoding
decode_func = {}
decode_func[b"l"] = self.decode_list
decode_func[b"d"] = self.decode_dict
decode_func[b"i"] = self.decode_int
decode_func[b"0"] = self.decode_bytes
decode_func[b"1"] = self.decode_bytes
decode_func[b"2"] = self.decode_bytes
decode_func[b"3"] = self.decode_bytes
decode_func[b"4"] = self.decode_bytes
decode_func[b"5"] = self.decode_bytes
decode_func[b"6"] = self.decode_bytes
decode_func[b"7"] = self.decode_bytes
decode_func[b"8"] = self.decode_bytes
decode_func[b"9"] = self.decode_bytes
self.decode_func = decode_func
def decode_int(self, x, f):
f += 1
newf = x.index(b"e", f)
n = int(x[f:newf])
if x[f : f + 2] == b"-0":
raise ValueError
elif x[f : f + 1] == b"0" and newf != f + 1:
raise ValueError
return (n, newf + 1)
def decode_bytes(self, x, f):
colon = x.index(b":", f)
n = int(x[f:colon])
if x[f : f + 1] == b"0" and colon != f + 1:
raise ValueError
colon += 1
d = x[colon : colon + n]
if self.bytestring_encoding:
d = d.decode(self.bytestring_encoding)
return (d, colon + n)
def decode_list(self, x, f):
r, f = [], f + 1
while x[f : f + 1] != b"e":
v, f = self.decode_func[x[f : f + 1]](x, f)
r.append(v)
if self.yield_tuples:
r = tuple(r)
return (r, f + 1)
def decode_dict(self, x, f):
r, f = {}, f + 1
lastkey = None
while x[f : f + 1] != b"e":
k, f = self.decode_bytes(x, f)
if lastkey is not None and lastkey >= k:
raise ValueError
lastkey = k
r[k], f = self.decode_func[x[f : f + 1]](x, f)
return (r, f + 1)
def bdecode(self, x):
if not isinstance(x, bytes):
raise TypeError
try:
r, l = self.decode_func[x[:1]](x, 0) # noqa: E741
except (IndexError, KeyError, OverflowError) as e:
raise ValueError(str(e))
if l != len(x): # noqa: E741
raise ValueError
return r
_decoder = BDecoder()
bdecode = _decoder.bdecode
_tuple_decoder = BDecoder(True)
bdecode_as_tuple = _tuple_decoder.bdecode
_utf8_decoder = BDecoder(bytestring_encoding="utf-8")
bdecode_utf8 = _utf8_decoder.bdecode
class Bencached:
__slots__ = ["bencoded"]
def __init__(self, s) -> None:
self.bencoded = s
class BEncoder:
def __init__(self, bytestring_encoding=None):
self.bytestring_encoding = bytestring_encoding
self.encode_func: Dict[Type, Callable[[object, List[bytes]], None]] = {
Bencached: self.encode_bencached,
int: self.encode_int,
bytes: self.encode_bytes,
list: self.encode_list,
tuple: self.encode_list,
dict: self.encode_dict,
bool: self.encode_bool,
str: self.encode_str,
}
def encode_bencached(self, x, r):
r.append(x.bencoded)
def encode_bool(self, x, r):
self.encode_int(int(x), r)
def encode_int(self, x, r):
r.extend((b"i", int_to_bytes(x), b"e"))
def encode_bytes(self, x, r):
r.extend((int_to_bytes(len(x)), b":", x))
def encode_list(self, x, r):
r.append(b"l")
for i in x:
self.encode(i, r)
r.append(b"e")
def encode_dict(self, x, r):
r.append(b"d")
ilist = sorted(x.items())
for k, v in ilist:
r.extend((int_to_bytes(len(k)), b":", k))
self.encode(v, r)
r.append(b"e")
def encode_str(self, x, r):
if self.bytestring_encoding is None:
raise TypeError(
"string found but no encoding specified. "
"Use bencode_utf8 rather bencode?"
)
return self.encode_bytes(x.encode(self.bytestring_encoding), r)
def encode(self, x, r):
self.encode_func[type(x)](x, r)
def int_to_bytes(n):
return b"%d" % n
def bencode(x):
r = []
encoder = BEncoder()
encoder.encode(x, r)
return b"".join(r)
def bencode_utf8(x):
r = []
encoder = BEncoder(bytestring_encoding="utf-8")
encoder.encode(x, r)
return b"".join(r)
|
