class Obfs3Daemon(BaseDaemon):
"""
Obfs2Daemon implements the obfs2 protocol.
It is subclassed by Obfs2Client and Obfs2Server.
"""
def __init__(self, circuit):
"""
Initializes the daemon with a downstream and upstream socket.
This also sets the protocol state to HANDSHAKE_WRITE and generates an ephemeral keypair.
"""
BaseDaemon.__init__(self, circuit)
self.state = HANDSHAKE_WRITE
self.ekeypair = createEphemeralKeypair()
self.epub = bytes('')
def start(self):
"""
This is the callback method which is called by the framework when a new connection has been made.
In the obfs3 protocol, on start the public part of the ephemeral keypair is written upstream.
"""
self.upstreamConnection.write(self.ekeypair.public.bytes)
def receivedDownstream(self):
"""
This is the callback method which is called by the framework when bytes have been received on the downstream socket.
In the obfs3 protocol, downstream bytes are buffered until the handshake is complete and the protocol is in STREAM mode, at which point all bytes received from downstream are encrypted and sent upstream.
"""
# If we're in streaming mode, encode and write the incoming data
if self.state == STREAM:
data = self.downstreamConnection.read_some()
if data:
self.upstreamConnection.write(self.coder.encode(data))
# Else do nothing, data will buffer until we've done the handshake
def receivedUpstream(self, data):
"""
This is the callback method which is called by the framework when bytes have been received on the upstream socket.
In the obfs3 protocol, the upstream handshake is read, and then the protocol is switched to STREAM mode, at which point all bytes received from upstream are encrypted and sent downstream.
"""
if self.state == HANDSHAKE:
self.epub = self.read(self.upstreamConnection, self.epub,
HANDSHAKE_SIZE)
if self.checkTransition(self.epub, HANDSHAKE_SIZE, STREAM):
esession = makeEphemeralSession(self.ekeypair,
self.epub)
self.coder = AESCoder(esession)
data = self.downstreamConnection.read_some()
if data:
self.upstreamConnection.write(self.coder.encode(data))
data = self.upstreamConnection.read_some()
if data:
self.downstreamConnection.write(self.coder.decode(data))
else:
data = self.upstreamConnection.read_some()
if data:
self.downstreamConnection.write(self.coder.decode(data))
def end(self):
"""
This is the callback method which is called by the framework when the connection is closed.
In Obfs3Daemon it does nothing.
"""
pass
def d(k, s):
""" D(k, s) is the AES-CTR-128 decryption of s using K as key. """
cipher = AESCoder(k)
return cipher.decode(s)
def d(k, s):
""" D(k, s) is the AES-CTR-128 decryption of s using K as key. """
cipher = AESCoder(k)
return cipher.decode(s)
class Obfs3Daemon(BaseDaemon):
"""
Obfs2Daemon implements the obfs2 protocol.
It is subclassed by Obfs2Client and Obfs2Server.
"""
def __init__(self, circuit):
"""
Initializes the daemon with a downstream and upstream socket.
This also sets the protocol state to HANDSHAKE_WRITE and generates an ephemeral keypair.
"""
BaseDaemon.__init__(self, circuit)
self.state = HANDSHAKE_WRITE
self.ekeypair = createEphemeralKeypair()
self.epub = bytes('')
def start(self):
"""
This is the callback method which is called by the framework when a new connection has been made.
In the obfs3 protocol, on start the public part of the ephemeral keypair is written upstream.
"""
self.upstreamConnection.write(self.ekeypair.public.bytes)
def receivedDownstream(self):
"""
This is the callback method which is called by the framework when bytes have been received on the downstream socket.
In the obfs3 protocol, downstream bytes are buffered until the handshake is complete and the protocol is in STREAM mode, at which point all bytes received from downstream are encrypted and sent upstream.
"""
# If we're in streaming mode, encode and write the incoming data
if self.state == STREAM:
data = self.downstreamConnection.read_some()
if data:
self.upstreamConnection.write(self.coder.encode(data))
# Else do nothing, data will buffer until we've done the handshake
def receivedUpstream(self, data):
"""
This is the callback method which is called by the framework when bytes have been received on the upstream socket.
In the obfs3 protocol, the upstream handshake is read, and then the protocol is switched to STREAM mode, at which point all bytes received from upstream are encrypted and sent downstream.
"""
if self.state == HANDSHAKE:
self.epub = self.read(self.upstreamConnection, self.epub,
HANDSHAKE_SIZE)
if self.checkTransition(self.epub, HANDSHAKE_SIZE, STREAM):
esession = makeEphemeralSession(self.ekeypair, self.epub)
self.coder = AESCoder(esession)
data = self.downstreamConnection.read_some()
if data:
self.upstreamConnection.write(self.coder.encode(data))
data = self.upstreamConnection.read_some()
if data:
self.downstreamConnection.write(self.coder.decode(data))
else:
data = self.upstreamConnection.read_some()
if data:
self.downstreamConnection.write(self.coder.decode(data))
def end(self):
"""
This is the callback method which is called by the framework when the connection is closed.
In Obfs3Daemon it does nothing.
"""
pass