def __init__(self):
self.am_choking = True
self.am_interested = False
self.peer_choking = True
self.peer_interested = False
self.handshaked = False
self.fast_extension = False
self.peer_bitfield = None
self.buf = ReadOnceBuffer()
self.requests = set()
class PeerProtocol(Protocol):
"""An instance of the BitTorrent protocol. Encapsulates a connection."""
id_to_msg = {None: 'keep_alive', 0: 'choke', 1: 'unchoke', 2: 'interested',
3: 'uninterested', 4: 'have', 5: 'bitfield', 6: 'request',
7: 'piece', 8: 'cancel', 9: 'port', 13: 'suggest_piece',
14: 'have_all', 15: 'have_none', 16: 'reject_request',
17: 'allowed_fast'}
extension_ids = frozenset((13, 14, 15, 16, 17))
def __init__(self):
self.am_choking = True
self.am_interested = False
self.peer_choking = True
self.peer_interested = False
self.handshaked = False
self.fast_extension = False
self.peer_bitfield = None
self.buf = ReadOnceBuffer()
self.requests = set()
def connectionMade(self):
self.send('handshake', info_hash=self.factory.torrent.info_hash,
peer_id=self.factory.client.client_id)
self.factory.protos.add(self)
def dataReceived(self, data):
self.buf += data
if not self.handshaked:
if self.bufsize >= HANDSHAKE_LEN:
self.parse_handshake(self.buf[:HANDSHAKE_LEN])
if all(self.factory.bitfield) and self.fast_extension:
self.send('have_all')
elif not any(self.factory.bitfield) and self.fast_extension:
self.send('have_none')
else:
self.send('bitfield', bitfield=self.factory.bitfield)
self.send('interested')
else:
self.transport.loseConnection()
while self.has_msg():
prefix, msg_id, payload = self.parse_message()
if msg_id in self.extension_ids and not self.fast_extension:
self.transport.loseConnection()
break
print 'about to do: %s' % self.id_to_msg[msg_id]
getattr(self, self.id_to_msg[msg_id])(payload)
self.factory.strategy()
def send(self, mtype, **kwargs):
"""Send a message to our peer, also take care of state that determines
who is choking who and who is interested."""
self.transport.write(Message(mtype, **kwargs))
if mtype == 'interested':
self.am_interested = True
elif mtype == 'not_interested':
self.am_interested = False
elif mtype == 'choke':
self.am_choking = True
elif mtype == 'unchoke':
self.am_choking = False
def has_msg(self):
"""Check if there is a full message to pull off, first 4 bytes
determine the necessary length and are not included in calc."""
return self.bufsize >= 4 and self.bufsize - 4 >= struct.unpack('!I', str(self.buf.peek(0, 4)))[0]
def keep_alive(self, *args):
pass
def choke(self, *args):
self.peer_choking = True
def unchoke(self, *args):
self.peer_choking = False
def interested(self, *args):
self.peer_interested = True
def uninterested(self, *args):
self.peer_interested = False
def have(self, payload):
if self.peer_bitfield is None:
self.peer_bitfield = bitarray(self.torrent_size * '0', endian='big')
self.peer_bitfield[struct.unpack('!I', str(payload))[0]] = True
def bitfield(self, payload):
self.peer_bitfield = bitarray(endian='big')
self.peer_bitfield.frombytes(str(payload))
def request(self, payload):
index, offset, size = struct.unpack('!III', payload)
if size > MAX_SIZE:
self.transport.loseConnection()
if self.factory.bitfield[index]:
block = self.factory.fetch(index, offset, size)
self.send('piece', index=index, offset=offset, block=block)
def piece(self, payload):
index, offset = struct.unpack_from('!II', str(payload))
block = payload[8:]
self.requests.remove((index, offset, len(block)))
self.factory.add_block(index, offset, block)
def cancel(self, payload):
pass
def port(self, payload):
"""Not supported"""
pass
def suggest_piece(self, payload):
index = struct.unpack('!I', payload)
if not self.factory.bitfield[index]:
pass # TODO
def allowed_fast(self, payload):
pass # TODO
def have_all(self, *args):
self.peer_bitfield = bitarray(self.torrent_size * '1', endian='big')
def have_none(self, *args):
self.peer_bitfield = bitarray(self.torrent_size * '0', endian='big')
def reject_request(self, payload):
index, offset, length = struct.unpack('!III', str(payload))
self.requests.remove((index, offset, length))
def parse_message(self):
prefix, = struct.unpack('!I', str(self.buf[:4]))
if not prefix: # keep_alive message, ID is None
return 0, None, None
message_id = self.buf[0]
if message_id < 4:
return prefix, message_id, None
else:
return prefix, message_id, self.buf[0: prefix-1] # -1 for id
def parse_handshake(self, data):
"""Verify the well formedness of the handshake and parse the extensions
supported by the peer. Connection is dropped if the handshake is not
well formed."""
if (data[0] != len(PSTR) or data[1:20] != PSTR
or data[28:48] != self.factory.torrent.info_hash):
self.transport.loseConnection()
else:
self.handshaked = True
reserved = data[20:28]
if reserved[7] & ord('\x04'):
self.fast_extension = True
def connectionLost(self, reason):
self.factory.protos.remove(self)
@property
def torrent_size(self):
return self.factory.torrent.n_pieces
@property
def bufsize(self):
return len(self.buf)
