single-pass continued wip

client.py

@@ -315,8 +315,9 @@ class ClientChannelManager(relay.ChannelManager):
         # Construct the SinglePassCreateCircuitMsg
         ntor = relay.NTor(self.perfstats)
         ntor_request = ntor.request()
+        ttl = 3 # TODO set a default for the msg type
         circcreatemsg = relay.SinglePassCreateCircuitMsg(circid, ntor_request,
-                client_key.public_key)
+                client_key.public_key, ttl)
 
         # Send the message
         guardchannel.send_msg(circcreatemsg)

relay.py

@@ -10,10 +10,21 @@ import nacl.signing
 import nacl.public
 import nacl.hash
 import nacl.bindings
+import hashlib
 
 import network
 import dirauth
 
+class VRF():
+    def __init__(self, private_key):
+        self.private_key = private_key
+
+    def get_output(self, vrf_input):
+        output = random.choice(str(vrf_input))
+        m = hashlib.sha256()
+        m.update(str(output).encode())
+        m.digest()
+
 class RelayNetMsg(network.NetMsg):
     """The subclass of NetMsg for messages between relays and either
     relays or clients."""
@@ -160,7 +171,7 @@ class TelescopingCreatedCircuitCell(RelayCell):
 
 class TelescopingExtendCircuitCell(RelayCell):
     """The message for requesting circuit extension in Telescoping Walking
-    Onionss."""
+    Onions."""
 
     def __init__(self, idx, ntor_request):
         self.idx = idx
@@ -176,20 +187,20 @@ class TelescopingExtendedCircuitCell(RelayCell):
 
 class SinglePassCreateCircuitMsg(RelayNetMsg):
     """The message for requesting circuit creation in Single Pass Onion
-    Routing."""
+    Routing. This is used to extend a Single-Pass circuit by clients."""
 
-    def __init__(self, circid, ntor_request, client_path_selection_key):
+    def __init__(self, circid, ntor_request, client_path_selection_key, ttl):
         self.circid = circid
         self.ntor_request = ntor_request
         self.client_path_selection_key = client_path_selection_key
+        self.ttl = ttl
 
 class SinglePassCreatedCircuitCell(RelayCell):
     """The message for responding to circuit creation in Single-Pass Walking
     Onions."""
 
-    def __init__(self, ntor_reply, circuit_snips):
+    def __init__(self, ntor_reply):
         self.ntor_reply = ntor_reply
-        self.circuit_snips = circuit_snips
 
 
 class EncryptedCell(RelayCell):
@@ -498,7 +509,7 @@ class TelescopingCreatedRelayHandler:
     def received_cell(self, circhandler, cell):
         logging.debug("Handle a TelescopingCreatedCircuit received by a relay")
         # Remove ourselves from handling a second
-        # VanillaCreatedCircuitCell on this circuit
+        # TelescopingCreatedCircuitCell on this circuit
         circhandler.replace_celltype_handler(TelescopingCreatedCircuitCell, None)
 
         # Just forward a TelescopingExtendedCircuitCell back towards the
@@ -506,6 +517,28 @@ class TelescopingCreatedRelayHandler:
         circhandler.adjacent_circuit_handler.send_cell(
             TelescopingExtendedCircuitCell(cell.ntor_reply, self.next_snip))
 
+class SinglePassCreatedRelayHandler:
+    """Handle a SinglePassCreatedCircuitCell received by a _relay_ that
+    recently received a SinglePassCreateCircuitMsg from this relay."""
+
+    def __init__(self, ntorreply, next_snip, vrf_output):
+        self.next_snip = next_snip
+        self.vrf_output = vrf_output
+        self.ntorreply = ntorreply
+
+    def received_cell(self, circhandler, cell):
+        logging.debug("Handle a SinglePassCreatedCircuitCell received by a relay")
+        # Remove ourselves from handling a second
+        # SinglePassCreatedCircuitCell on this circuit
+        circhandler.replace_celltype_handler(SinglePassCreatedCircuitCell, None)
+
+        # Just forward a SinglePassCreatedCircuitCell back towards the
+        # client
+        circhandler.adjacent_circuit_handler.send_cell(
+            SinglePassCreatedCircuitCell(cell.ntor_reply, self.next_snip))
+
+        sys.exit("have not yet implemented circuit handling for single-pass in relays")
+
 class CircuitHandler:
     """A class for managing sending and receiving encrypted cells on a
     particular circuit."""
@@ -879,11 +912,37 @@ class RelayChannelManager(ChannelManager):
             # Send the ntor reply
             self.send_msg(CircuitCellMsg(msg.circid,
                     TelescopingCreatedCircuitCell(reply)), peeraddr)
-        elif isinstance(msg, SinglePassCreateCircuitMsg):
+        elif isinstance(msg, SinglePassCreateCircuitMsg) and msg.ttl == 0:
+            # we are the end of the circuit, just establish a shared key and
+            # return
+            logging.debug("RelayChannelManager: Single-Pass TTL is 0, replying without extending")
+
             # A new circuit has arrived
             circhandler = channel.new_circuit_with_circid(msg.circid)
+
+            # Create the ntor reply
+            reply, secret = NTor.reply(self.onionkey, self.idpubkey,
+                msg.ntor_request, self.perfstats)
+            # Set up the circuit to use the shared secret
+            enckey = nacl.hash.sha256(secret + b'downstream')
+            deckey = nacl.hash.sha256(secret + b'upstream')
+            circhandler.add_crypt_layer(enckey, deckey)
+
+            # Send the ntor reply
+            self.send_msg(CircuitCellMsg(msg.circid,
+                SinglePassCreatedCircuitCell(reply)), peeraddr)
+
+        elif isinstance(msg, SinglePassCreateCircuitMsg) and msg.ttl > 0:
+            # A new circuit has arrived
+            circhandler = channel.new_circuit_with_circid(msg.circid)
+
+            # because the ttl is greater than 0, we need to extend the circuit. To do this, we
+            # need to derive the client's blinded keys, deterministically
+            # select the next relay in the circuit, etc.
+            logging.debug("RelayChannelManager: Single-Pass TTL is greater than 0; extending")
+
             # Create the ntor reply for the circuit-extension key
-            (reply, secret), blinded_client_pubkey = NTor.reply(self.onionkey, self.idpubkey,
+            (ntorreply, secret), blinded_client_encr_key = NTor.reply(self.onionkey, self.idpubkey,
                     msg.ntor_request, self.perfstats,  b'circuit')
 
             # Set up the circuit to use the shared secret established from the
@@ -892,45 +951,45 @@ class RelayChannelManager(ChannelManager):
             deckey = nacl.hash.sha256(secret + b'upstream')
             circhandler.add_crypt_layer(enckey, deckey)
 
-            logging.debug("WARNING: Unimplemented! Should check the TTL, if it isn't \
-                    zero, decriment it and pass it along. Otherwise, just reply \
-                    without extending.")
-
-            # here, we will directly extend the circuit ourselves, after doing
-            # the following:
-            # 1. determining the next relay using the client's path selection
-            #    key in conjunction with our own
-            # 2. blinding each of the client's public keys to send to the next
-            #    hop.
-            idx_as_hex, blinded_client_pubkey = Sphinx.server(msg.client_path_selection_key,
+            # here, we will directly extend the circuit ourselves, after
+            # determining the next relay using the client's path selection
+            # key in conjunction with our own
+            idx_as_hex, blinded_client_path_selection_key = Sphinx.server(msg.client_path_selection_key,
             self.path_selection_key, b'circuit', False, self.perfstats)
 
             logging.debug("RelayChannelManager: Unimplemented! need to translate idx into endive index")
             logging.debug("RelayChannelManager: Unimplemented! need to pick the next relay using the shared secret between the client and the relay.")
 
-            nexthop = self.relaypicker.pick_weighted_relay()
-            if nexthop == None:
-                logging.debug("WARNING: Unimplemented! Need to validate next hop is not null, if it is, we should send a CLOSE cell.")
+            # TODO temporary
+            next_hop = None
+            while next_hop == None or next_hop.snipdict["idkey"] == self.idpubkey:
+                logging.debug("WARNING: Unimplemented! Need to validate next hop is not null or ourselves, if it is, we should send a CLOSE cell.")
+                idx = self.relaypicker.pick_weighted_relay_index()
+                next_hop = self.relaypicker.pick_relay_by_uniform_index(idx)
+
+            # simpulate the VRF output for now
+            vrf_output = VRF(self.onionkey).get_output(idx)
+
+            # Allocate a new circuit id to the requested next hop
+            channelmgr = circhandler.channel.channelmgr
+            nexthopchannel = channelmgr.get_channel_to(next_hop.snipdict["addr"])
+            newcircid, newcirchandler = nexthopchannel.new_circuit()
+
+            # Connect the existing and new circuits together
+            circhandler.adjacent_circuit_handler = newcirchandler
+            newcirchandler.adjacent_circuit_handler = circhandler
 
             # Add a handler for once the next relay replies to say that the
             # circuit has been created
             # be at most one on this circuit).
             circhandler.replace_celltype_handler(
                     SinglePassCreatedCircuitCell,
-                    SinglePassCreatedCircuitHandler(ntorreply, next_hop))
-
-#            # Allocate a new circuit id to the requested next hop
-#            channelmgr = circhandler.channel.channelmgr
-#            nexthopchannel = channelmgr.get_channel_to(next_snip.snipdict["addr"])
-#            newcircid, newcirchandler = nexthopchannel.new_circuit()
-#
-#            # Send the next create message to the next hop
-#            # TODO add the correct interface here
-#            self.send_msg(CircuitCellMsg(msg.circid,
-#                    SinglePassCreateCircuitCell(newcircid, ntorrequest,
-#                        next_client_path_selection_key)), peeraddr)
-#
-            sys.exit("have not yet implemented circuit handling for single-pass in relays")
+                    SinglePassCreatedRelayHandler(ntorreply, next_hop, vrf_output))
+
+            # Send the next create message to the next hop
+            nexthopchannel.send_msg(SinglePassCreateCircuitMsg(newcircid,
+                blinded_client_encr_key, blinded_client_path_selection_key,
+                msg.ttl-1))
         else:
             return super().received_msg(msg, peeraddr, channel)