def receivedDownstream(self, data):
"""
Got data from downstream. We need to de-obfuscate them and
proxy them upstream.
"""
log_prefix = "obfs2 receivedDownstream" # used in logs
if self.state == ST_WAIT_FOR_KEY:
log.debug("%s: Waiting for key." % log_prefix)
if len(data) < SEED_LENGTH + 8:
log.debug("%s: Not enough bytes for key (%d)." % (log_prefix, len(data)))
return data # incomplete
if self.we_are_initiator:
self.responder_seed = data.read(SEED_LENGTH)
else:
self.initiator_seed = data.read(SEED_LENGTH)
# Now that we got the other seed, let's set up our crypto.
self.send_crypto = self._derive_crypto(self.send_keytype)
self.recv_crypto = self._derive_crypto(self.recv_keytype)
self.recv_padding_crypto = \
self._derive_padding_crypto(self.responder_seed if self.we_are_initiator else self.initiator_seed,
self.recv_pad_keytype)
# XXX maybe faster with a single d() instead of two.
magic = srlz.ntohl(self.recv_padding_crypto.crypt(data.read(4)))
padding_length = srlz.ntohl(self.recv_padding_crypto.crypt(data.read(4)))
log.debug("%s: Got %d bytes of handshake data (padding_length: %d, magic: %s)" % \
(log_prefix, len(data), padding_length, hex(magic)))
if magic != MAGIC_VALUE:
raise base.PluggableTransportError("obfs2: Corrupted magic value '%s'" % hex(magic))
if padding_length > MAX_PADDING:
raise base.PluggableTransportError("obfs2: Too big padding length '%s'" % padding_length)
self.padding_left_to_read = padding_length
self.state = ST_WAIT_FOR_PADDING
while self.padding_left_to_read:
if not data: return
n_to_drain = self.padding_left_to_read
if (self.padding_left_to_read > len(data)):
n_to_drain = len(data)
data.drain(n_to_drain)
self.padding_left_to_read -= n_to_drain
log.debug("%s: Consumed %d bytes of padding, %d still to come (%d).",
log_prefix, n_to_drain, self.padding_left_to_read, len(data))
self.state = ST_OPEN
log.debug("%s: Processing %d bytes of application data.",
log_prefix, len(data))
if self.pending_data_to_send:
log.debug("%s: We got pending data to send and our crypto is ready. Pushing!" % log_prefix)
self.receivedUpstream(self.circuit.upstream.buffer) # XXX touching guts of network.py
self.pending_data_to_send = False
self.circuit.upstream.write(self.recv_crypto.crypt(data.read()))
def receivedDownstream(self, data):
"""
Got data from downstream. We need to de-obfuscate them and
proxy them upstream.
"""
log_prefix = "obfs2 receivedDownstream" # used in logs
if self.state == ST_WAIT_FOR_KEY:
log.debug("%s: Waiting for key." % log_prefix)
if len(data) < SEED_LENGTH + 8:
log.debug("%s: Not enough bytes for key (%d)." % (log_prefix, len(data)))
return data # incomplete
if self.we_are_initiator:
self.responder_seed = data.read(SEED_LENGTH)
else:
self.initiator_seed = data.read(SEED_LENGTH)
# Now that we got the other seed, let's set up our crypto.
self.send_crypto = self._derive_crypto(self.send_keytype)
self.recv_crypto = self._derive_crypto(self.recv_keytype)
self.recv_padding_crypto = \
self._derive_padding_crypto(self.responder_seed if self.we_are_initiator else self.initiator_seed,
self.recv_pad_keytype)
# XXX maybe faster with a single d() instead of two.
magic = srlz.ntohl(self.recv_padding_crypto.crypt(data.read(4)))
padding_length = srlz.ntohl(self.recv_padding_crypto.crypt(data.read(4)))
log.debug("%s: Got %d bytes of handshake data (padding_length: %d, magic: %s)" % \
(log_prefix, len(data), padding_length, hex(magic)))
if magic != MAGIC_VALUE:
raise base.PluggableTransportError("obfs2: Corrupted magic value '%s'" % hex(magic))
if padding_length > MAX_PADDING:
raise base.PluggableTransportError("obfs2: Too big padding length '%s'" % padding_length)
self.padding_left_to_read = padding_length
self.state = ST_WAIT_FOR_PADDING
while self.padding_left_to_read:
if not data: return
n_to_drain = self.padding_left_to_read
if (self.padding_left_to_read > len(data)):
n_to_drain = len(data)
data.drain(n_to_drain)
self.padding_left_to_read -= n_to_drain
log.debug("%s: Consumed %d bytes of padding, %d still to come (%d).",
log_prefix, n_to_drain, self.padding_left_to_read, len(data))
self.state = ST_OPEN
log.debug("%s: Processing %d bytes of application data.",
log_prefix, len(data))
if self.pending_data_to_send:
log.debug("%s: We got pending data to send and our crypto is ready. Pushing!" % log_prefix)
self.receivedUpstream(self.circuit.upstream.buffer) # XXX touching guts of network.py
self.pending_data_to_send = False
self.circuit.upstream.write(self.recv_crypto.crypt(data.read()))