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import argparse
import asyncio
import logging
import tuntap
from aiortc import RTCIceCandidate, RTCPeerConnection, RTCSessionDescription
from aiortc.contrib.signaling import BYE, add_signaling_arguments, create_signaling
logger = logging.Logger("vpn")
def channel_log(channel, t, message):
logger.info("channel(%s) %s %s" % (channel.label, t, repr(message)))
async def consume_signaling(pc, signaling):
while True:
obj = await signaling.receive()
if isinstance(obj, RTCSessionDescription):
await pc.setRemoteDescription(obj)
if obj.type == "offer":
# send answer
await pc.setLocalDescription(await pc.createAnswer())
await signaling.send(pc.localDescription)
elif isinstance(obj, RTCIceCandidate):
await pc.addIceCandidate(obj)
elif obj is BYE:
print("Exiting")
break
def tun_start(tap, channel):
tap.open()
# relay channel -> tap
channel.on("message")(tap.fd.write)
# relay tap -> channel
def tun_reader():
data = tap.fd.read(tap.mtu)
if data:
channel.send(data)
loop = asyncio.get_event_loop()
loop.add_reader(tap.fd, tun_reader)
tap.up()
async def run_answer(pc, signaling, tap):
await signaling.connect()
@pc.on("datachannel")
def on_datachannel(channel):
channel_log(channel, "-", "created by remote party")
if channel.label == "vpntap":
tun_start(tap, channel)
await consume_signaling(pc, signaling)
async def run_offer(pc, signaling, tap):
await signaling.connect()
channel = pc.createDataChannel("vpntap")
channel_log(channel, "-", "created by local party")
@channel.on("open")
def on_open():
tun_start(tap, channel)
# send offer
await pc.setLocalDescription(await pc.createOffer())
await signaling.send(pc.localDescription)
await consume_signaling(pc, signaling)
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="VPN over data channel")
parser.add_argument("role", choices=["offer", "answer"])
parser.add_argument("--verbose", "-v", action="count")
add_signaling_arguments(parser)
args = parser.parse_args()
if args.verbose:
logging.basicConfig(level=logging.DEBUG)
tap = tuntap.Tun(name="revpn-%s" % args.role)
signaling = create_signaling(args)
pc = RTCPeerConnection()
if args.role == "offer":
coro = run_offer(pc, signaling, tap)
else:
coro = run_answer(pc, signaling, tap)
# run event loop
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(coro)
except KeyboardInterrupt:
pass
finally:
loop.run_until_complete(pc.close())
loop.run_until_complete(signaling.close())
tap.close()
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