commit 2b7a86b3bb2db582123f800f992d8683c65cc3e4 Author: Quinn Jarrell qjarrell@gosynapsify.com Date: Thu Jun 5 14:40:20 2014 -0400

Modified pt_launch_pair into pt_launch_chain. The new method of chaining starts with the last socks server pointing to the last pt with the destination being the bridge server. Then the middle pts are chained in reverse order. Finally the first socks server is started at the callback port and links to the second pt. The helper function pt_setup_socks_proxy takes care of setting up a specific SOCKS server. --- obfs-flash-client | 68 ++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 49 insertions(+), 19 deletions(-)

diff --git a/obfs-flash-client b/obfs-flash-client index 963d48a..7fae6b8 100755 --- a/obfs-flash-client +++ b/obfs-flash-client @@ -246,17 +246,36 @@ def pt_require_child(client, childmethod, pt_method_name, cmethods): raise ValueError() return cmethods[childmethod]

-def pt_launch_pair(reactor, client, callback_port, configuration, pt_method_name): +def pt_setup_socks_proxy(pt_name, pt_chain, success_list, dest_address, dest_port, reactor, listen_port=0): + """Launches a socks proxy server to link two PTs together. + :param str pt_name: The name of the pt to send traffic to. + :param list pt_chain: The list of PTs in this chain. + :param list success_list: A list of tuples containing a launch status boolean, MethodSpec pairs. + Ex: [(True, MethodSpec(name='dummy', protocol='socks4', addrport=('127.0.0.1', 58982), args=[], opts=[])), + (True, MethodSpec(name='b64', protocol='socks4', addrport=('127.0.0.1', 58981), args=[], opts=[]))] + :param str dest_address: The address for the next PT to send its results to. + :param int dest_port: The port for the next PT to send to. + :param twisted.internet.interfaces.IReactor reactor: Reactor to attack the TCP server to. + :param int listen_port. The port to for the TCP server to listen on. Default is chosen by the OS.""" + + methodspec = [r[1] for r in success_list if r[1].name == pt_name][0] # Returns the resulting methodspec. + proxy_server = reactor.listenTCP(interface='127.0.0.1', port=listen_port, factory= + SOCKS4WrapperFactory(methodspec.addrport[0], methodspec.addrport[1], dest_address, dest_port)) + return proxy_server.getHost().port + +def pt_launch_chain(reactor, client, callback_port, configuration, pt_method_name): """ - Launches a pair of pluggable transports. Currently only supports chaining two transports together. - The pair is set by pt_method_names + Launches a chain of pluggable transports. :param twisted.internet.interfaces.IReactor reactor: Reactor to install this PT to. :param pyptlib.client.ClientTransportPlugin client: PT client API. :param int callback_port: Local listen port for the first PT to connect to. :param Config configuration: The configuration structure for this pair. - :param String pt_method_name: The name of the pt chain to launch. Ex: "obfs3_flashproxy" + :param str pt_method_name: The name of the pt chain to launch. Ex: "obfs3_flashproxy" """ - #TODO Modify pt_launch_pair to launch more than 2 transports + + # Temporary hardcoded ip/port + dest_address = '127.0.0.1' + dest_port = 2400

if pt_method_name in configuration.alias_map: pt_chain = configuration.alias_map[pt_method_name] @@ -266,19 +285,22 @@ def pt_launch_pair(reactor, client, callback_port, configuration, pt_method_name

defer_list = []

+ if len(pt_chain) < 2: + raise ValueError("PT Chain %s does not contain enough transports." % pt_chain) + for pt in pt_chain: if pt in configuration.transport_map: pt_cmdline = configuration.transport_map[pt] else: - logging.error("Pluggable transport %s not found in transport_map. Check your configuration file." % str(pt)) - raise ValueError() + raise ValueError("Pluggable transport %s not found in transport_map. Check your configuration file." % pt) _, _, defer = pt_launch_child(reactor, client, [pt], pt_method_name, pt_cmdline) defer_list.extend(defer) whenAllDone = DeferredList(defer_list, consumeErrors=False)

def allDone(success_list): """ - :param success_list: A list of tuples containing a launch status boolean, MethodSpec pairs. + Connects the pluggable transports together through SOCKS proxies. + :param list success_list: A list of tuples containing a launch status boolean, MethodSpec pairs. Ex: [(True, MethodSpec(name='dummy', protocol='socks4', addrport=('127.0.0.1', 58982), args=[], opts=[])), (True, MethodSpec(name='b64', protocol='socks4', addrport=('127.0.0.1', 58981), args=[], opts=[]))] """ @@ -287,14 +309,22 @@ def pt_launch_pair(reactor, client, callback_port, configuration, pt_method_name # failure was already reported by pt_require_child, just return if not success: return

- result1 = [r[1] for r in success_list if r[1].name == pt_chain[0]][0] # Normally obfs3 result - result2 = [r[1] for r in success_list if r[1].name == pt_chain[1]][0] # Normally flashproxy result - destination_port = result2.addrport[1] # if port was 0, read the actual port - # shim to wrap obfs data output to SOCKS input for flashproxy - reactor.listenTCP(interface='127.0.0.1', port=callback_port, factory= - SOCKS4WrapperFactory('127.0.0.1', destination_port, '0.0.1.0', 1)) + #This TCP server forwards the data to the last pt, which then sends the data to the actual bridge address + last_pt_name = pt_chain[-1] + # Initialize prev_port to the first port picked by the last proxy as that's the only one we know yet. + prev_port = pt_setup_socks_proxy(last_pt_name, pt_chain, success_list, dest_address, dest_port, reactor) + + for pt_name in reversed(pt_chain[1:-1]): + #Loops through the middle pts linking them together through SOCKS proxies, skipping the first and last pts. + prev_port = pt_setup_socks_proxy(pt_name, pt_chain, success_list, '127.0.0.1', prev_port, reactor) + + # Links the first server to listen on the given callback_port and forward data from the first pt onto the next. + first_pt_name = pt_chain[0] + pt_setup_socks_proxy(first_pt_name, pt_chain, success_list, '127.0.0.1', prev_port, reactor, listen_port=callback_port) + # now report success of the overall composed PT - client.reportMethodSuccess(pt_method_name, result1.protocol, result1.addrport) + first_methodspec = [r[1] for r in success_list if r[1].name == first_pt_name and r[1].name in pt_chain][0] + client.reportMethodSuccess(pt_method_name, first_methodspec.protocol, first_methodspec.addrport) client.reportMethodsEnd() whenAllDone.addCallback(allDone)

@@ -321,7 +351,7 @@ class Config(): def parse(cls, config_string): """ Reads a configuration string and returns an instance of configuration. Uses shlex to parse configuration lines. - :param String config_string: The string which will be parsed to populate the transport_map and alias_map hash tables. + :param str config_string: The string which will be parsed to populate the transport_map and alias_map hash tables. See the file example-fog-config for format. """ # TODO Add possibility of reading a ClientTransportPlugin with multiple transport types @@ -387,7 +417,7 @@ def obfs3_flashproxy(reactor, client, callback_port, fp_remote, fp_args=[], fp_l alias_map = {'obfs3_flashproxy': ['obfs3', 'flashproxy']}

configuration = Config(transport_map, alias_map) - pt_launch_pair(reactor, client, callback_port, configuration, "obfs3_flashproxy") # Launch + pt_launch_chain(reactor, client, callback_port, configuration, "obfs3_flashproxy") # Launch

def main(*args): parser = argparse.ArgumentParser() @@ -408,7 +438,7 @@ def main(*args):

opts = parser.parse_args(args)

- # ensure str address is valid + # ensure string address is valid _, _, = parse_addr_spec(opts.fp_remote, defhost="0.0.0.0") configuration = None

@@ -429,7 +459,7 @@ def main(*args): auto_killall(1, cleanup=reactor.stop) #TODO Change from launching a single pair to launching multiple chains. if configuration: - pt_launch_pair(reactor, client, opts.callback_port, configuration, pt_method_names[0]) + pt_launch_chain(reactor, client, opts.callback_port, configuration, pt_method_names[0]) else: logging.warn("No configuration file specified. Defaulting to launching obfs3|flashproxy pair.") obfs3_flashproxy(reactor, client, opts.callback_port, opts.fp_remote, opts.fp_arg or [])