147 lines
3.3 KiB
Python
147 lines
3.3 KiB
Python
'''
|
|
A Python 3 translation of bcode.py
|
|
https://pypi.python.org/pypi/bcode/0.5
|
|
'''
|
|
|
|
def bencode(data):
|
|
'''
|
|
Encode python types to bencode.
|
|
'''
|
|
if data is None:
|
|
return None
|
|
|
|
data_type = type(data)
|
|
|
|
encoders = {
|
|
bytes: encode_bytes,
|
|
str: encode_string,
|
|
float: encode_float,
|
|
int: encode_int,
|
|
dict: encode_dict,
|
|
}
|
|
|
|
encoder = encoders.get(data_type, None)
|
|
if encoder is None:
|
|
try:
|
|
return encode_iterator(iter(data))
|
|
except TypeError:
|
|
raise ValueError('Invalid field type %s' % data_type)
|
|
return encoder(data)
|
|
|
|
def encode_bytes(data):
|
|
return '%d:%s' % (len(data), data)
|
|
|
|
def encode_dict(data):
|
|
result = []
|
|
keys = list(data.keys())
|
|
keys.sort()
|
|
for key in keys:
|
|
result.append(bencode(key))
|
|
result.append(bencode(data[key]))
|
|
result = ''.join(result)
|
|
return 'd%se' % result
|
|
|
|
def encode_float(data):
|
|
return encode_string(str(data))
|
|
|
|
def encode_int(data):
|
|
return 'i%de' % data
|
|
|
|
def encode_iterator(data):
|
|
result = []
|
|
for item in data:
|
|
result.append(bencode(item))
|
|
result = ''.join(result)
|
|
return 'l%se' % result
|
|
|
|
def encode_string(data):
|
|
return encode_bytes(data)
|
|
|
|
|
|
# =============================================================================
|
|
|
|
|
|
def bdecode(data):
|
|
'''
|
|
Decode bencode to python types.
|
|
|
|
Returns a dictionary
|
|
{
|
|
'result': the decoded item
|
|
'remainder': what's left of the input text
|
|
}
|
|
'''
|
|
if data is None:
|
|
return None
|
|
|
|
data = data.strip()
|
|
if isinstance(data, bytes):
|
|
data = data.decode('utf-8')
|
|
|
|
if data[0] == 'i':
|
|
return decode_int(data)
|
|
|
|
if data[0].isdigit():
|
|
return decode_string(data)
|
|
|
|
if data[0] == 'l':
|
|
return decode_list(data)
|
|
|
|
if data[0] == 'd':
|
|
return decode_dict(data)
|
|
|
|
raise ValueError('Invalid initial delimiter "%s"' % data[0])
|
|
|
|
def decode_dict(data):
|
|
result = {}
|
|
|
|
# slice leading d
|
|
remainder = data[1:]
|
|
while remainder[0] != 'e':
|
|
temp = bdecode(remainder)
|
|
key = temp['result']
|
|
remainder = temp['remainder']
|
|
|
|
temp = bdecode(remainder)
|
|
value = temp['result']
|
|
remainder = temp['remainder']
|
|
|
|
result[key] = value
|
|
|
|
# slice ending 3
|
|
remainder = remainder[1:]
|
|
return {'result': result, 'remainder': remainder}
|
|
|
|
def decode_int(data):
|
|
end = data.find('e')
|
|
if end == -1:
|
|
raise ValueError('Missing end delimiter "e"')
|
|
|
|
# slice leading i and closing e
|
|
result = data[1:end]
|
|
remainder = data[end+1:]
|
|
return {'result': result, 'remainder': remainder}
|
|
|
|
def decode_list(data):
|
|
result = []
|
|
|
|
# slice leading l
|
|
remainder = data[1:]
|
|
while remainder[0] != 'e':
|
|
item = bdecode(data)
|
|
result.append(item['result'])
|
|
reaminder = item['remainder']
|
|
|
|
# slice ending e
|
|
remainder = remainder[1:]
|
|
return {'result': result, 'remainder': remainder}
|
|
|
|
def decode_string(data):
|
|
start = data.find(':') + 1
|
|
size = int(data[:start-1])
|
|
end = start + size
|
|
text = data[start:end]
|
|
if len(text) < size:
|
|
raise ValueError('Actual length %d is less than declared length %d' % len(text), size)
|
|
remainder = data[end:]
|
|
return {'result': text, 'remainder': remainder}
|