-
Notifications
You must be signed in to change notification settings - Fork 0
/
bencode.py
87 lines (63 loc) · 2.12 KB
/
bencode.py
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
from collections import OrderedDict
from itertools import islice, takewhile
from typing import IO, Any, Iterator
def dumps(v: Any) -> str:
"""Bencodes any type of data into a string"""
if isinstance(v, int):
return f'i{v}e'
elif isinstance(v, str):
return f'{len(v)}:{v}'
elif isinstance(v, bytes):
return f'{len(v)}:{v.decode("utf8")}'
elif isinstance(v, list):
return f'l{"".join(dumps(i) for i in v)}e'
elif isinstance(v, dict | OrderedDict):
out = 'd'
for key, value in v.items():
key = dumps(key)
value = dumps(value)
out += f'{key}{value}'
return out + 'e'
def dump(data: Any, io: IO[bytes], encoding: str = 'utf8') -> None:
"""Bencodes data and writes the bytes result into the io"""
encoded = dumps(data).encode(encoding)
io.write(encoded)
def sdump(data: Any, io: IO[str]) -> None:
"""Bencodes data and writes the string result into the io"""
encoded = dumps(data)
io.write(encoded)
def loads(data: bytes) -> Any:
"""Unpacks bencoded data"""
it = iter(data)
return _loads(it)
def _loads(it: Iterator) -> Any:
ch = next(it)
if ch == 0x69: # 'i': int
digits = takewhile(lambda x: x != 0x65, it)
return int(bytes(digits))
elif 48 <= ch <= 57: # '0' < ch < '9': string | bytes
length = [ch, *takewhile(lambda x: x != 0x3a, it)]
length = int(''.join(chr(i) for i in length))
return bytes(islice(it, length))
elif ch == 0x6c: # 'l': list
arr = []
while True:
item = _loads(it)
if item is None:
break
arr.append(item)
return arr
elif ch == 0x64: # 'd': dictionary
odict = OrderedDict()
while True:
key = _loads(it)
if key is None:
break
value = _loads(it)
odict[key] = value
return odict
elif ch == 0x65: # 'e': end of the list or dict
return None
def load(io: IO[bytes]) -> Any:
"""Reads benocded data from the io"""
return loads(io.read())