walkingonions/client.py

#!/usr/bin/env python3

import random # For simulation, not cryptography!
import math

import network
import dirauth
import relay

import nacl.hash

class VanillaCreatedExtendedHandler:
    """A handler for VanillaCreatedCircuitCell and
    VanillaExtendedCircuitCell cells."""

    def __init__(self, channelmgr, ntor, expecteddesc):
        self.channelmgr = channelmgr
        self.ntor = ntor
        self.expecteddesc = expecteddesc
        self.onionkey = expecteddesc.descdict['onionkey']
        self.idkey = expecteddesc.descdict['idkey']

    def received_cell(self, circhandler, cell):
        secret = self.ntor.verify(cell.ntor_reply, self.onionkey, self.idkey)
        enckey = nacl.hash.sha256(secret + b'upstream')
        deckey = nacl.hash.sha256(secret + b'downstream')
        circhandler.add_crypt_layer(enckey, deckey)
        if len(circhandler.circuit_descs) == 0:
            # This was a VanillaCreatedCircuitCell
            circhandler.replace_celltype_handler(
                    relay.VanillaCreatedCircuitCell, None)
        else:
            # This was a VanillaExtendedCircuitCell
            circhandler.replace_celltype_handler(
                    relay.VanillaExtendedCircuitCell, None)
        circhandler.circuit_descs.append(self.expecteddesc)

        # Are we done building the circuit?
        if len(circhandler.circuit_descs) == 3:
            # Yes!
            return

        nexthop = None
        while nexthop is None:
            nexthop = self.channelmgr.consensus.select_weighted_relay(
                    self.channelmgr.consensus_cdf)
            if nexthop.descdict['addr'] in \
                    [ desc.descdict['addr'] \
                        for desc in circhandler.circuit_descs ]:
                nexthop = None

        # Construct the VanillaExtendCircuitCell
        ntor = relay.NTor(self.channelmgr.perfstats)
        ntor_request = ntor.request()
        circextendmsg = relay.VanillaExtendCircuitCell(
                nexthop.descdict['addr'], ntor_request)

        # Set up the reply handler
        circhandler.replace_celltype_handler(
                relay.VanillaExtendedCircuitCell,
                VanillaCreatedExtendedHandler(self.channelmgr, ntor, nexthop))

        # Send the cell
        circhandler.send_cell(circextendmsg)


class ClientChannelManager(relay.ChannelManager):
    """The subclass of ChannelManager for clients."""

    def __init__(self, myaddr, dirauthaddrs, perfstats):
        super().__init__(myaddr, dirauthaddrs, perfstats)
        self.guardaddr = None
        self.guard = None
        if network.thenetwork.womode == network.WOMode.VANILLA:
            self.consensus_cdf = []

    def get_consensus_from_fallbackrelay(self):
        """Download a fresh consensus from a random fallbackrelay."""
        fb = random.choice(network.thenetwork.getfallbackrelays())
        if self.consensus is not None and \
                len(self.consensus.consdict['relays']) > 0:
            self.send_msg(relay.RelayGetConsensusDiffMsg(), fb.netaddr)
        else:
            self.send_msg(relay.RelayGetConsensusMsg(), fb.netaddr)

    def ensure_guard_vanilla(self):
        """Ensure that we have a channel to a guard (Vanilla Onion
        Routing version)."""
        while True:
            if self.guardaddr is None:
                # Pick a guard from the consensus
                self.guard = self.consensus.select_weighted_relay(self.consensus_cdf)
                self.guardaddr = self.guard.descdict['addr']

            # Connect to the guard
            try:
                self.get_channel_to(self.guardaddr)
            except network.NetNoServer:
                # Our guard is gone
                self.guardaddr = None
                self.guard = None

            if self.guardaddr is not None:
                break

        print('chose guard=', self.guardaddr)

    def ensure_guard(self):
        """Ensure that we have a channel to a guard."""
        if network.thenetwork.womode == network.WOMode.VANILLA:
            self.ensure_guard_vanilla()

    def new_circuit_vanilla(self):
        """Create a new circuit from this client. (Vanilla Onion Routing
        version)"""

        # Get our channel to the guard
        guardchannel = self.get_channel_to(self.guardaddr)

        # Allocate a new circuit id on it
        circid, circhandler = guardchannel.new_circuit()

        # Construct the VanillaCreateCircuitMsg
        ntor = relay.NTor(self.perfstats)
        ntor_request = ntor.request()
        circcreatemsg = relay.VanillaCreateCircuitMsg(circid, ntor_request)

        # Set up the reply handler
        circhandler.replace_celltype_handler(
                relay.VanillaCreatedCircuitCell,
                VanillaCreatedExtendedHandler(self, ntor, self.guard))

        # Send the message
        guardchannel.send_msg(circcreatemsg)

        return circhandler

    def new_circuit(self):
        """Create a new circuit from this client."""
        if network.thenetwork.womode == network.WOMode.VANILLA:
            return self.new_circuit_vanilla()

    def received_msg(self, msg, peeraddr, channel):
        """Callback when a NetMsg not specific to a circuit is
        received."""
        print("Client %s received msg %s from %s" % (self.myaddr, msg, peeraddr))
        if isinstance(msg, relay.RelayConsensusMsg) or \
                isinstance(msg, relay.RelayConsensusDiffMsg):
            dirauth.Consensus.verify(msg.consensus,
                    network.thenetwork.dirauthkeys(), self.perfstats)
            self.consensus = msg.consensus
            if network.thenetwork.womode == network.WOMode.VANILLA:
                self.consensus_cdf = self.consensus.bw_cdf()
        else:
            return super().received_msg(msg, peeraddr, channel)

    def received_cell(self, circid, cell, peeraddr, channel):
        """Callback with a circuit-specific cell is received."""
        print("Client %s received cell on circ %d: %s from %s" % (self.myaddr, circid, cell, peeraddr))
        return super().received_cell(circid, cell, peeraddr, channel)


class Client:
    """A class representing a Tor client."""

    def __init__(self, dirauthaddrs):
        # Get a network address for client-side use only (do not bind it
        # to the network)
        self.netaddr = network.NetAddr()
        self.perfstats = network.PerfStats(network.EntType.CLIENT)
        self.perfstats.name = "Client at %s" % self.netaddr
        self.perfstats.is_bootstrapping = True
        self.channelmgr = ClientChannelManager(self.netaddr, dirauthaddrs, self.perfstats)

        # Register for epoch tick notifications
        network.thenetwork.wantepochticks(self, True)

    def terminate(self):
        """Quit this client."""

        # Stop listening for epoch ticks
        network.thenetwork.wantepochticks(self, False)

        # Close relay connections
        self.channelmgr.terminate()

    def get_consensus(self):
        """Fetch a new consensus."""

        # We're going to want a new consensus from our guard.  In order
        # to get that, we'll need a channel to our guard.  In order to
        # get that, we'll need a guard address.  In order to get that,
        # we'll need a consensus (uh, oh; in that case, fetch the
        # consensus from a fallback relay).

        guardaddr = self.channelmgr.guardaddr
        guardchannel = None
        if guardaddr is not None:
            try:
                guardchannel = self.channelmgr.get_channel_to(guardaddr)
            except network.NetNoServer:
                guardaddr = None

        if guardchannel is None:
            self.channelmgr.get_consensus_from_fallbackrelay()
        else:
            if self.channelmgr.consensus is not None and \
                    len(self.channelmgr.consensus.consdict['relays']) > 0:
                guardchannel.send_msg(relay.RelayGetConsensusDiffMsg())
            else:
                guardchannel.send_msg(relay.RelayGetConsensusMsg())

        print('client consensus=', self.channelmgr.consensus)

    def newepoch(self, epoch):
        """Callback that fires at the start of each epoch"""

        # We'll need a new consensus
        self.get_consensus()

        # If we don't have a guard, pick one and make a channel to it
        self.channelmgr.ensure_guard()



if __name__ == '__main__':
    perfstats = network.PerfStats(network.EntType.NONE)
    totsent = 0
    totrecv = 0
    dirasent = 0
    dirarecv = 0
    relaysent = 0
    relayrecv = 0
    clisent = 0
    clirecv = 0

    # Start some dirauths
    numdirauths = 9
    dirauthaddrs = []
    dirauths = []
    for i in range(numdirauths):
        dira = dirauth.DirAuth(i, numdirauths)
        dirauths.append(dira)
        dirauthaddrs.append(dira.netaddr)

    # Start some relays
    numrelays = 10
    relays = []
    for i in range(numrelays):
        # Relay bandwidths (at least the ones fast enough to get used)
        # in the live Tor network (as of Dec 2019) are well approximated
        # by (200000-(200000-25000)/3*log10(x)) where x is a
        # uniform integer in [1,2500]
        x = random.randint(1,2500)
        bw = int(200000-(200000-25000)/3*math.log10(x))
        relays.append(relay.Relay(dirauthaddrs, bw, 0))

    # The fallback relays are a hardcoded list of about 5% of the
    # relays, used by clients for bootstrapping
    numfallbackrelays = int(numrelays * 0.05) + 1
    fallbackrelays = random.sample(relays, numfallbackrelays)
    for r in fallbackrelays:
        r.set_is_fallbackrelay()
    network.thenetwork.setfallbackrelays(fallbackrelays)

    # Tick the epoch
    network.thenetwork.nextepoch()

    dirauth.Consensus.verify(dirauth.DirAuth.consensus, network.thenetwork.dirauthkeys(), perfstats)

    print('ticked; epoch=', network.thenetwork.getepoch())

    relays[3].channelmgr.send_msg(relay.RelayRandomHopMsg(30), relays[5].netaddr)

    # See what channels exist and do a consistency check
    for r in relays:
        print("%s: %s" % (r.netaddr, [ str(k) for k in r.channelmgr.channels.keys()]))
        raddr = r.netaddr
        for ad, ch in r.channelmgr.channels.items():
            if ch.peer.channelmgr.myaddr != ad:
                print('address mismatch:', raddr, ad, ch.peer.channelmgr.myaddr)

            if ch.peer.channelmgr.channels[raddr].peer is not ch:
                print('asymmetry:', raddr, ad, ch, ch.peer.channelmgr.channels[raddr].peer)

    # Start some clients
    numclients = 1
    clients = []
    for i in range(numclients):
        clients.append(Client(dirauthaddrs))

    # Tick the epoch
    network.thenetwork.nextepoch()

    # See what channels exist and do a consistency check
    for c in clients:
        print("%s: %s" % (c.netaddr, [ str(k) for k in c.channelmgr.channels.keys()]))
        caddr = c.netaddr
        for ad, ch in c.channelmgr.channels.items():
            if ch.peer.channelmgr.myaddr != ad:
                print('address mismatch:', caddr, ad, ch.peer.channelmgr.myaddr)

            if ch.peer.channelmgr.channels[caddr].peer is not ch:
                print('asymmetry:', caddr, ad, ch, ch.peer.channelmgr.channels[caddr].peer)

    # Pick a bunch of bw-weighted random relays and look at the
    # distribution
    for i in range(100):
        r = clients[0].channelmgr.consensus.select_weighted_relay(clients[0].channelmgr.consensus_cdf)
        print("relay",r.descdict["addr"])

    relays[3].terminate()
    relaysent += relays[3].perfstats.bytes_sent
    relayrecv += relays[3].perfstats.bytes_received
    del relays[3]

    # Tick the epoch
    network.thenetwork.nextepoch()

    circs = []
    for i in range(20):
        circ = clients[0].channelmgr.new_circuit()
        circs.append(circ)
        circ.send_cell(relay.StringCell("hello world circuit %d" % i))

    # Tick the epoch
    network.thenetwork.nextepoch()

    # See what channels exist and do a consistency check
    for r in relays:
        print("%s: %s" % (r.netaddr, [ str(k) + str([ck for ck in r.channelmgr.channels[k].circuithandlers.keys()]) for k in r.channelmgr.channels.keys()]))
        raddr = r.netaddr
        for ad, ch in r.channelmgr.channels.items():
            if ch.peer.channelmgr.myaddr != ad:
                print('address mismatch:', raddr, ad, ch.peer.channelmgr.myaddr)

            if ch.peer.channelmgr.channels[raddr].peer is not ch:
                print('asymmetry:', raddr, ad, ch, ch.peer.channelmgr.channels[raddr].peer)

    # See what channels exist and do a consistency check
    for c in clients:
        print("%s: %s" % (c.netaddr, [ str(k) + str([ck for ck in c.channelmgr.channels[k].circuithandlers.keys()]) for k in c.channelmgr.channels.keys()]))
        caddr = c.netaddr
        for ad, ch in c.channelmgr.channels.items():
            if ch.peer.channelmgr.myaddr != ad:
                print('address mismatch:', caddr, ad, ch.peer.channelmgr.myaddr)

            if ch.peer.channelmgr.channels[caddr].peer is not ch:
                print('asymmetry:', caddr, ad, ch, ch.peer.channelmgr.channels[caddr].peer)

            if ch.circuithandlers.keys() != \
                    ch.peer.channelmgr.channels[caddr].circuithandlers.keys():
                print('circuit asymmetry:', caddr, ad, ch.peer.channelmgr.myaddr)

    for c in circs:
        c.close()

    for d in dirauths:
        print(d.perfstats)
        dirasent += d.perfstats.bytes_sent
        dirarecv += d.perfstats.bytes_received
    print("DirAuths sent=%s recv=%s" % (dirasent, dirarecv))
    totsent += dirasent
    totrecv += dirarecv
    for r in relays:
        print(r.perfstats)
        relaysent += r.perfstats.bytes_sent
        relayrecv += r.perfstats.bytes_received
    print("Relays sent=%s recv=%s" % (relaysent, relayrecv))
    totsent += relaysent
    totrecv += relayrecv
    for c in clients:
        print(c.perfstats)
        clisent += c.perfstats.bytes_sent
        clirecv += c.perfstats.bytes_received
    print("Client sent=%s recv=%s" % (clisent, clirecv))
    totsent += clisent
    totrecv += clirecv

    print("Total sent=%s recv=%s" % (totsent, totrecv))