/
peerproxy.py
255 lines (196 loc) · 8.51 KB
/
peerproxy.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
"""
The PeerProxy represents a BitTorrent peer and communicates with and maintains
state associated with that peer. A PeerProxy can be created in one of two ways
which reflect whether it or the remote end is initiating the connection. When
no socket is supplied, the PeerProxy is expected to initiate the connection and
handshake with the peer. When a socket is supplied, the far end has already
initiated the connection and the PeerProxy should wait for a handshake from the
far end.
The PeerProxy maintains the state of the connection through six states.
When the far end initiates a connection, the PeerProxy starts off in the
Awaiting_Handshake state. Upon receiving a handshake, it moves to the
Bitfield_Allowed state. When the PeerProxy initiates the connection, it starts
off in Awaiting_Connection state. When it receives notification that a
connection has been made, it sends a handshake and moves into
Handshake_Initiated state. Upon receiving a handshake back, it moves into
Bitfield_Allowed. Bitfield_Allowed is the only state in which a bitfield
message may be received. When any message is received in Bitfield_Allowed,
the state is changed to Peer_to_Peer. When a bitfield message is received in
any state other than Bitfield_Allowed, the connection is dropped and the state
is changed to Disconnected.
The PeerProxy uses a translator to interpret the incoming stream of bytes into
higher level messages and to construct outgoing messages into a stream of
bytes. Initially, the PeerProxy uses a HandshakeTranslator to translate the
"handshake" protocol. After the handshake has been established, it sets up a
PeerWireTranslator to translate the peer wire protocol.
Currently, the PeerProxy does not handle or generate keep alives at all.
"""
import logging
from connector import Connector
from handshaketranslator import HandshakeTranslator
from peerwiretranslator import PeerWireTranslator
from socketreaderwriter import SocketReaderWriter
logger = logging.getLogger('bt.peerproxy')
class PeerProxy(object):
class _States(object):
(Awaiting_Handshake, Awaiting_Connection, Handshake_Initiated,
Bitfield_Allowed, Peer_to_Peer, Disconnected) = range(6)
def __init__(self, client, peer_id, addr, socket=None, info_hash=None):
self._client = client
self._socket = socket
self._info_hash = info_hash
self._peer_id = peer_id
self._addr = addr
self._choked = True
self._interested = False
self._peer_choked = True
self._peer_interested = False
if len(peer_id) != 20:
raise ValueError("Peer id must be 20 bytes long")
if socket is None:
if info_hash is None or len(info_hash) != 20:
raise ValueError("Info hash must be a 20 byte value")
self._translator = None
self._socketreaderwriter = None
Connector().connect(addr, self)
self._state = self._States.Awaiting_Connection
else:
self._setup_handshake_translator()
self._state = self._States.Awaiting_Handshake
def _setup_handshake_translator(self):
self._socketreaderwriter = SocketReaderWriter(self._socket)
self._translator = HandshakeTranslator()
self._translator.set_readerwriter(self._socketreaderwriter)
self._translator.set_receiver(self)
def _drop_connection(self, notify_client=True):
if self._translator is not None:
self._translator.unset_receiver()
self._translator.unset_readerwriter()
self._translator = None
if self._socketreaderwriter:
self._socketreaderwriter.stop()
if self._socket is not None:
self._socket.close()
self._state = self._States.Disconnected
if notify_client:
self._client.peer_unconnected(self)
def _valid_rx_state(self):
if self._state != self._States.Peer_to_Peer:
if self._state == self._States.Bitfield_Allowed:
self._state = self._States.Peer_to_Peer
else:
if self._state != self._States.Disconnected:
self._drop_connection()
return False
return True
def _valid_tx_state(self):
if self._state != self._States.Peer_to_Peer:
if self._state == self._States.Bitfield_Allowed:
self._state = self._States.Peer_to_Peer
else:
return False
return True
def addr(self):
return self._addr
def is_interested(self):
return self._interested
def is_choked(self):
return self._choked
def is_peer_choked(self):
return self._peer_choked
def is_peer_interested(self):
return self._peer_interested
# Connector callbacks
def connection_complete(self, addr, socket):
self._socket = socket
self._setup_handshake_translator()
self._translator.tx_handshake(0, self._info_hash, self._peer_id)
self._state = self._States.Handshake_Initiated
def connection_failed(self, addr):
self._client.peer_unconnected(self)
# Translator callbacks
def connection_lost(self):
self._drop_connection()
# HandshakeTranslator callbacks
def rx_handshake(self, reserved, info_hash, peer_id):
if self._state == self._States.Handshake_Initiated:
if info_hash != self._info_hash:
self._drop_connection()
else:
self._translator.unset_receiver()
self._translator.unset_readerwriter()
self._translator = PeerWireTranslator()
self._translator.set_readerwriter(self._socketreaderwriter)
self._translator.set_receiver(self)
self._state = self._States.Bitfield_Allowed
self._translator.tx_bitfield(self._client.get_bitfield())
def rx_non_handshake(self):
self._drop_connection()
# PeerWireTranslator callbacks
def rx_bitfield(self, bitfield):
if self._state == self._States.Bitfield_Allowed:
self._state = self._States.Peer_to_Peer
self._client.peer_bitfield(self, bitfield)
else:
self._drop_connection()
def rx_keep_alive(self):
pass
def rx_choke(self):
if self._valid_rx_state():
self._peer_choked = True
self._client.peer_choked(self)
def rx_unchoke(self):
if self._valid_rx_state():
self._peer_choked = False
self._client.peer_unchoked(self)
def rx_interested(self):
if self._valid_rx_state():
self._peer_interested = True
self._client.peer_interested(self)
def rx_not_interested(self):
if self._valid_rx_state():
self._peer_interested = False
self._client.peer_not_interested(self)
def rx_have(self, index):
if self._valid_rx_state():
self._client.peer_has(self, index)
def rx_request(self, index, begin, length):
if self._valid_rx_state():
self._client.peer_requests(self, index, begin, length)
def rx_piece(self, index, begin, buf):
if self._valid_rx_state():
self._client.peer_sent_block(self, index, begin, buf)
def rx_cancel(self, index, begin, length):
if self._valid_rx_state():
self._client.peer_canceled(self, index, begin, length)
# Client calls
def drop_connection(self):
self._drop_connection(False)
def choke(self):
if self._valid_tx_state():
self._choked = True
self._translator.tx_choke()
def unchoke(self):
if self._valid_tx_state():
self._choked = False
self._translator.tx_unchoke()
def interested(self):
if self._valid_tx_state():
self._interested = True
self._translator.tx_interested()
def not_interested(self):
if self._valid_tx_state():
self._interested = False
self._translator.tx_not_interested()
def have(self, index):
if self._valid_tx_state():
self._translator.tx_have(index)
def request(self, index, begin, length):
if self._valid_tx_state():
self._translator.tx_request(index, begin, length)
def piece(self, index, begin, buf, offset):
if self._valid_tx_state():
self._translator.tx_piece(index, begin, buf)
def cancel(self, index, begin, length):
if self._valid_tx_state():
self._translator.tx_cancel(index, begin, length)