# Written by Bram Cohen
# see LICENSE.txt for license information
from cStringIO import StringIO
from binascii import b2a_hex
from urllib import quote
import Connecter
try:
True
except:
True = 1
False = 0
DEBUG = False
protocol_name = 'BitTorrent protocol'
option_pattern = chr(0)*8
def toint(s):
return long(b2a_hex(s), 16)
def tohex(s):
return b2a_hex(s).upper()
def make_readable(s):
if not s:
return ''
if quote(s).find('%') >= 0:
return tohex(s)
return '"'+s+'"'
# header, reserved, download id, my id, [length, message]
streamno = 0
class StreamCheck:
def __init__(self):
global streamno
self.no = streamno
streamno += 1
self.buffer = StringIO()
self.next_len, self.next_func = 1, self.read_header_len
def read_header_len(self, s):
if ord(s) != len(protocol_name):
print self.no, 'BAD HEADER LENGTH'
return len(protocol_name), self.read_header
def read_header(self, s):
if s != protocol_name:
print self.no, 'BAD HEADER'
return 8, self.read_reserved
def read_reserved(self, s):
return 20, self.read_download_id
def read_download_id(self, s):
if DEBUG:
print self.no, 'download ID ' + tohex(s)
return 20, self.read_peer_id
def read_peer_id(self, s):
if DEBUG:
print self.no, 'peer ID' + make_readable(s)
return 4, self.read_len
def read_len(self, s):
l = toint(s)
if l > 2 ** 23:
print self.no, 'BAD LENGTH: '+str(l)+' ('+s+')'
return l, self.read_message
def read_message(self, s):
if not s:
return 4, self.read_len
m = s[0]
if ord(m) > 8:
print self.no, 'BAD MESSAGE: '+str(ord(m))
if m == Connecter.REQUEST:
if len(s) != 13:
print self.no, 'BAD REQUEST SIZE: '+str(len(s))
return 4, self.read_len
index = toint(s[1:5])
begin = toint(s[5:9])
length = toint(s[9:])
print self.no, 'Request: '+str(index)+': '+str(begin)+'-'+str(begin)+'+'+str(length)
elif m == Connecter.CANCEL:
if len(s) != 13:
print self.no, 'BAD CANCEL SIZE: '+str(len(s))
return 4, self.read_len
index = toint(s[1:5])
begin = toint(s[5:9])
length = toint(s[9:])
print self.no, 'Cancel: '+str(index)+': '+str(begin)+'-'+str(begin)+'+'+str(length)
elif m == Connecter.PIECE:
index = toint(s[1:5])
begin = toint(s[5:9])
length = len(s)-9
print self.no, 'Piece: '+str(index)+': '+str(begin)+'-'+str(begin)+'+'+str(length)
else:
print self.no, 'Message '+str(ord(m))+' (length '+str(len(s))+')'
return 4, self.read_len
def write(self, s):
while 1:
i = self.next_len - self.buffer.tell()
if i > len(s):
self.buffer.write(s)
return
self.buffer.write(s[:i])
s = s[i:]
m = self.buffer.getvalue()
self.buffer.reset()
self.buffer.truncate()
x = self.next_func(m)
self.next_len, self.next_func = x
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