src/backend/tracker.py

   1 #!/usr/bin/python
   2
   3 from __future__ import division
   4
   5 def ncode_hex(s):
   6         return s.encode("hex")
   7
   8 def decode_hex(s):
   9         return s.decode("hex")
  10
  11 ##### This is borrowed from the bittorrent client libary #####
  12
  13 def decode_int(x, f):
  14     f += 1
  15     newf = x.index('e', f)
  16     n = int(x[f:newf])
  17     if x[f] == '-':
  18         if x[f + 1] == '0':
  19             raise ValueError
  20     elif x[f] == '0' and newf != f+1:
  21         raise ValueError
  22     return (n, newf+1)
  23
  24 def decode_string(x, f):
  25     colon = x.index(':', f)
  26     n = int(x[f:colon])
  27     if x[f] == '0' and colon != f+1:
  28         raise ValueError
  29     colon += 1
  30     return (x[colon:colon+n], colon+n)
  31
  32 def decode_list(x, f):
  33     r, f = [], f+1
  34     while x[f] != 'e':
  35         v, f = decode_func[x[f]](x, f)
  36         r.append(v)
  37     return (r, f + 1)
  38
  39 def decode_dict(x, f):
  40     r, f = {}, f+1
  41     while x[f] != 'e':
  42         k, f = decode_string(x, f)
  43         r[k], f = decode_func[x[f]](x, f)
  44     return (r, f + 1)
  45
  46 decode_func = {}
  47 decode_func['l'] = decode_list
  48 decode_func['d'] = decode_dict
  49 decode_func['i'] = decode_int
  50 decode_func['0'] = decode_string
  51 decode_func['1'] = decode_string
  52 decode_func['2'] = decode_string
  53 decode_func['3'] = decode_string
  54 decode_func['4'] = decode_string
  55 decode_func['5'] = decode_string
  56 decode_func['6'] = decode_string
  57 decode_func['7'] = decode_string
  58 decode_func['8'] = decode_string
  59 decode_func['9'] = decode_string
  60
  61 def bdecode(x):
  62     try:
  63         r, l = decode_func[x[0]](x, 0)
  64     except (IndexError, KeyError, ValueError):
  65         raise Exception("not a valid bencoded string")
  66     if l != len(x):
  67         raise Exception("invalid bencoded value (data after valid prefix)")
  68     return r
  69
  70 from types import StringType, IntType, LongType, DictType, ListType, TupleType
  71
  72
  73 class Bencached(object):
  74
  75     __slots__ = ['bencoded']
  76
  77     def __init__(self, s):
  78         self.bencoded = s
  79
  80 def encode_bencached(x,r):
  81     r.append(x.bencoded)
  82
  83 def encode_int(x, r):
  84     r.extend(('i', str(x), 'e'))
  85
  86 def encode_bool(x, r):
  87     if x:
  88         encode_int(1, r)
  89     else:
  90         encode_int(0, r)
  91
  92 def encode_string(x, r):
  93     r.extend((str(len(x)), ':', x))
  94
  95 def encode_list(x, r):
  96     r.append('l')
  97     for i in x:
  98         encode_func[type(i)](i, r)
  99     r.append('e')
 100
 101 def encode_dict(x,r):
 102     r.append('d')
 103     ilist = x.items()
 104     ilist.sort()
 105     for k, v in ilist:
 106         r.extend((str(len(k)), ':', k))
 107         encode_func[type(v)](v, r)
 108     r.append('e')
 109
 110 encode_func = {}
 111 encode_func[Bencached] = encode_bencached
 112 encode_func[IntType] = encode_int
 113 encode_func[LongType] = encode_int
 114 encode_func[StringType] = encode_string
 115 encode_func[ListType] = encode_list
 116 encode_func[TupleType] = encode_list
 117 encode_func[DictType] = encode_dict
 118
 119 try:
 120     from types import BooleanType
 121     encode_func[BooleanType] = encode_bool
 122 except ImportError:
 123     pass
 124
 125 def bencode(x):
 126     r = []
 127     encode_func[type(x)](x, r)
 128     return ''.join(r)