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# The contents of this file are subject to the BitTorrent Open Source License
# Version 1.1 (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.bittorrent.com/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 Bram Cohen
from cStringIO import StringIO
from socket import error as socketerror
protocol_name = 'BitTorrent protocol'
# header, reserved, download id, my id, [length, message]
class NatCheck(object):
def __init__(self, resultfunc, downloadid, peerid, ip, port, rawserver):
self.resultfunc = resultfunc
self.downloadid = downloadid
self.peerid = peerid
self.ip = ip
self.port = port
self.closed = False
self.buffer = StringIO()
self.next_len = 1
self.next_func = self.read_header_len
rawserver.async_start_connection((ip, port), self)
def connection_started(self, s):
self.connection = s
self.connection.write(chr(len(protocol_name)) + protocol_name +
(chr(0) * 8) + self.downloadid)
def connection_failed(self, addr, exception):
self.answer(False)
def answer(self, result):
self.closed = True
try:
self.connection.close()
except AttributeError:
pass
self.resultfunc(result, self.downloadid, self.peerid, self.ip, self.port)
def read_header_len(self, s):
if ord(s) != len(protocol_name):
return None
return len(protocol_name), self.read_header
def read_header(self, s):
if s != protocol_name:
return None
return 8, self.read_reserved
def read_reserved(self, s):
return 20, self.read_download_id
def read_download_id(self, s):
if s != self.downloadid:
return None
return 20, self.read_peer_id
def read_peer_id(self, s):
if s != self.peerid:
return None
self.answer(True)
return None
def data_came_in(self, connection, s):
while True:
if self.closed:
return
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)
if x is None:
if not self.closed:
self.answer(False)
return
self.next_len, self.next_func = x
def connection_lost(self, connection):
if not self.closed:
self.closed = True
self.resultfunc(False, self.downloadid, self.peerid, self.ip, self.port)
def connection_flushed(self, connection):
pass
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