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bencode.py
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bencode.py
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# Written by Petru Paler, Uoti Urpala, Ross Cohen and John Hoffman
# see LICENSE.txt for license information
from types import IntType, LongType, StringType, ListType, TupleType, DictType
try:
from types import BooleanType
except ImportError:
BooleanType = None
try:
from types import UnicodeType
except ImportError:
UnicodeType = None
from cStringIO import StringIO
def decode_int(x, f):
f += 1
newf = x.index('e', f)
try:
n = int(x[f:newf])
except:
n = long(x[f:newf])
if x[f] == '-':
if x[f + 1] == '0':
raise ValueError
elif x[f] == '0' and newf != f+1:
raise ValueError
return (n, newf+1)
def decode_string(x, f):
colon = x.index(':', f)
try:
n = int(x[f:colon])
except (OverflowError, ValueError):
n = long(x[f:colon])
if x[f] == '0' and colon != f+1:
raise ValueError
colon += 1
return (x[colon:colon+n], colon+n)
def decode_unicode(x, f):
s, f = decode_string(x, f+1)
return (s.decode('UTF-8'),f)
def decode_list(x, f):
r, f = [], f+1
while x[f] != 'e':
v, f = decode_func[x[f]](x, f)
r.append(v)
return (r, f + 1)
def decode_dict(x, f):
r, f = {}, f+1
lastkey = None
while x[f] != 'e':
k, f = decode_string(x, f)
if lastkey >= k:
raise ValueError
lastkey = k
r[k], f = decode_func[x[f]](x, f)
return (r, f + 1)
decode_func = {}
decode_func['l'] = decode_list
decode_func['d'] = decode_dict
decode_func['i'] = decode_int
decode_func['0'] = decode_string
decode_func['1'] = decode_string
decode_func['2'] = decode_string
decode_func['3'] = decode_string
decode_func['4'] = decode_string
decode_func['5'] = decode_string
decode_func['6'] = decode_string
decode_func['7'] = decode_string
decode_func['8'] = decode_string
decode_func['9'] = decode_string
#decode_func['u'] = decode_unicode
def bdecode(x, sloppy = 0):
try:
r, l = decode_func[x[0]](x, 0)
# except (IndexError, KeyError):
except (IndexError, KeyError, ValueError):
raise ValueError, "bad bencoded data"
if not sloppy and l != len(x):
raise ValueError, "bad bencoded data"
return r
def test_bdecode():
try:
bdecode('0:0:')
assert 0
except ValueError:
pass
try:
bdecode('ie')
assert 0
except ValueError:
pass
try:
bdecode('i341foo382e')
assert 0
except ValueError:
pass
assert bdecode('i4e') == 4L
assert bdecode('i0e') == 0L
assert bdecode('i123456789e') == 123456789L
assert bdecode('i-10e') == -10L
try:
bdecode('i-0e')
assert 0
except ValueError:
pass
try:
bdecode('i123')
assert 0
except ValueError:
pass
try:
bdecode('')
assert 0
except ValueError:
pass
try:
bdecode('i6easd')
assert 0
except ValueError:
pass
try:
bdecode('35208734823ljdahflajhdf')
assert 0
except ValueError:
pass
try:
bdecode('2:abfdjslhfld')
assert 0
except ValueError:
pass
assert bdecode('0:') == ''
assert bdecode('3:abc') == 'abc'
assert bdecode('10:1234567890') == '1234567890'
try:
bdecode('02:xy')
assert 0
except ValueError:
pass
try:
bdecode('l')
assert 0
except ValueError:
pass
assert bdecode('le') == []
try:
bdecode('leanfdldjfh')
assert 0
except ValueError:
pass
assert bdecode('l0:0:0:e') == ['', '', '']
try:
bdecode('relwjhrlewjh')
assert 0
except ValueError:
pass
assert bdecode('li1ei2ei3ee') == [1, 2, 3]
assert bdecode('l3:asd2:xye') == ['asd', 'xy']
assert bdecode('ll5:Alice3:Bobeli2ei3eee') == [['Alice', 'Bob'], [2, 3]]
try:
bdecode('d')
assert 0
except ValueError:
pass
try:
bdecode('defoobar')
assert 0
except ValueError:
pass
assert bdecode('de') == {}
assert bdecode('d3:agei25e4:eyes4:bluee') == {'age': 25, 'eyes': 'blue'}
assert bdecode('d8:spam.mp3d6:author5:Alice6:lengthi100000eee') == {'spam.mp3': {'author': 'Alice', 'length': 100000}}
try:
bdecode('d3:fooe')
assert 0
except ValueError:
pass
try:
bdecode('di1e0:e')
assert 0
except ValueError:
pass
try:
bdecode('d1:b0:1:a0:e')
assert 0
except ValueError:
pass
try:
bdecode('d1:a0:1:a0:e')
assert 0
except ValueError:
pass
try:
bdecode('i03e')
assert 0
except ValueError:
pass
try:
bdecode('l01:ae')
assert 0
except ValueError:
pass
try:
bdecode('9999:x')
assert 0
except ValueError:
pass
try:
bdecode('l0:')
assert 0
except ValueError:
pass
try:
bdecode('d0:0:')
assert 0
except ValueError:
pass
try:
bdecode('d0:')
assert 0
except ValueError:
pass
bencached_marker = []
class Bencached:
def __init__(self, s):
self.marker = bencached_marker
self.bencoded = s
BencachedType = type(Bencached('')) # insufficient, but good as a filter
def encode_bencached(x,r):
assert x.marker == bencached_marker
r.append(x.bencoded)
def encode_int(x,r):
r.extend(('i',str(x),'e'))
def encode_bool(x,r):
encode_int(int(x),r)
def encode_string(x,r):
r.extend((str(len(x)),':',x))
def encode_unicode(x,r):
#r.append('u')
encode_string(x.encode('UTF-8'),r)
def encode_list(x,r):
r.append('l')
for e in x:
encode_func[type(e)](e, r)
r.append('e')
def encode_dict(x,r):
r.append('d')
ilist = x.items()
ilist.sort()
for k,v in ilist:
r.extend((str(len(k)),':',k))
encode_func[type(v)](v, r)
r.append('e')
encode_func = {}
encode_func[BencachedType] = encode_bencached
encode_func[IntType] = encode_int
encode_func[LongType] = encode_int
encode_func[StringType] = encode_string
encode_func[ListType] = encode_list
encode_func[TupleType] = encode_list
encode_func[DictType] = encode_dict
if BooleanType:
encode_func[BooleanType] = encode_bool
if UnicodeType:
encode_func[UnicodeType] = encode_unicode
def bencode(x):
r = []
try:
encode_func[type(x)](x, r)
except:
print "*** error *** could not encode type %s (value: %s)" % (type(x), x)
assert 0
return ''.join(r)
def test_bencode():
assert bencode(4) == 'i4e'
assert bencode(0) == 'i0e'
assert bencode(-10) == 'i-10e'
assert bencode(12345678901234567890L) == 'i12345678901234567890e'
assert bencode('') == '0:'
assert bencode('abc') == '3:abc'
assert bencode('1234567890') == '10:1234567890'
assert bencode([]) == 'le'
assert bencode([1, 2, 3]) == 'li1ei2ei3ee'
assert bencode([['Alice', 'Bob'], [2, 3]]) == 'll5:Alice3:Bobeli2ei3eee'
assert bencode({}) == 'de'
assert bencode({'age': 25, 'eyes': 'blue'}) == 'd3:agei25e4:eyes4:bluee'
assert bencode({'spam.mp3': {'author': 'Alice', 'length': 100000}}) == 'd8:spam.mp3d6:author5:Alice6:lengthi100000eee'
try:
bencode({1: 'foo'})
assert 0
except AssertionError:
pass
try:
import psyco
psyco.bind(bdecode)
psyco.bind(bencode)
except ImportError:
pass