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# The contents of this file are subject to the Python Software Foundation
# License Version 2.3 (the License). You may not copy or use this file, in
# either source code or executable form, except in compliance with the License.
# You may obtain a copy of the License at http://www.python.org/license.
#
# Software distributed under the License is distributed on an AS IS basis,
# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
# for the specific language governing rights and limitations under the
# License.
# Written by Petru Paler
# Updated by Calum Lind to support Python 3.
class BTFailure(Exception):
pass
DICT_DELIM = b'd'
END_DELIM = b'e'
INT_DELIM = b'i'
LIST_DELIM = b'l'
BYTE_SEP = b':'
def decode_int(x, f):
f += 1
newf = x.index(END_DELIM, f)
n = int(x[f:newf])
if x[f : f + 1] == b'-' and x[f + 1 : 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_string(x, f):
colon = x.index(BYTE_SEP, f)
n = int(x[f:colon])
if x[f : f + 1] == b'0' and colon != f + 1:
raise ValueError
colon += 1
return (x[colon : colon + n], colon + n)
def decode_list(x, f):
r, f = [], f + 1
while x[f : f + 1] != END_DELIM:
v, f = decode_func[x[f : f + 1]](x, f)
r.append(v)
return (r, f + 1)
def decode_dict(x, f):
r, f = {}, f + 1
while x[f : f + 1] != END_DELIM:
k, f = decode_string(x, f)
r[k], f = decode_func[x[f : f + 1]](x, f)
return (r, f + 1)
decode_func = {}
decode_func[LIST_DELIM] = decode_list
decode_func[DICT_DELIM] = decode_dict
decode_func[INT_DELIM] = decode_int
decode_func[b'0'] = decode_string
decode_func[b'1'] = decode_string
decode_func[b'2'] = decode_string
decode_func[b'3'] = decode_string
decode_func[b'4'] = decode_string
decode_func[b'5'] = decode_string
decode_func[b'6'] = decode_string
decode_func[b'7'] = decode_string
decode_func[b'8'] = decode_string
decode_func[b'9'] = decode_string
def bdecode(x):
try:
r, __ = decode_func[x[0:1]](x, 0)
except (LookupError, TypeError, ValueError):
raise BTFailure('Not a valid bencoded string')
else:
return r
class Bencached:
__slots__ = ['bencoded']
def __init__(self, s):
self.bencoded = s
def encode_bencached(x, r):
r.append(x.bencoded)
def encode_int(x, r):
r.extend((INT_DELIM, str(x).encode('utf8'), END_DELIM))
def encode_bool(x, r):
encode_int(1 if x else 0, r)
def encode_string(x, r):
encode_bytes(x.encode('utf8'), r)
def encode_bytes(x, r):
r.extend((str(len(x)).encode('utf8'), BYTE_SEP, x))
def encode_list(x, r):
r.append(LIST_DELIM)
for i in x:
encode_func[type(i)](i, r)
r.append(END_DELIM)
def encode_dict(x, r):
r.append(DICT_DELIM)
for k, v in sorted(x.items()):
try:
k = k.encode('utf8')
except AttributeError:
pass
r.extend((str(len(k)).encode('utf8'), BYTE_SEP, k))
encode_func[type(v)](v, r)
r.append(END_DELIM)
encode_func = {}
encode_func[Bencached] = encode_bencached
encode_func[int] = encode_int
encode_func[list] = encode_list
encode_func[tuple] = encode_list
encode_func[dict] = encode_dict
encode_func[bool] = encode_bool
encode_func[str] = encode_string
encode_func[bytes] = encode_bytes
def bencode(x):
r = []
encode_func[type(x)](x, r)
return b''.join(r)
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