add beginnings of tunnel code #35

.vscode/launch.json

@@ -20,6 +20,14 @@
       "justMyCode": true,
       "args": ["--info"]
     },
+    {
+      "name": "meshtastic tunnel",
+      "type": "python",
+      "request": "launch",
+      "module": "meshtastic",
+      "justMyCode": true,
+      "args": ["--tunnel", "--debug"]
+    },
     {
       "name": "meshtastic debug",
       "type": "python",

meshtastic/__main__.py

@@ -1,7 +1,7 @@
 #!python3
 
 import argparse
-from . import SerialInterface, TCPInterface, BLEInterface, test, remote_hardware
+from . import SerialInterface, TCPInterface, BLEInterface, test, remote_hardware, tunnel
 import logging
 import sys
 from pubsub import pub
@@ -274,6 +274,11 @@ def onConnected(interface):
             print(f"Channel URL {interface.channelURL}")
             url = pyqrcode.create(interface.channelURL)
             print(url.terminal())
+
+        if args.tunnel:
+            closeNow = False # Even if others said we could close, stay open if the user asked for a tunnel
+            tunnel.Tunnel(interface)
+           
     except Exception as ex:
         print(ex)
 
@@ -394,6 +399,9 @@ def main():
     parser.add_argument('--unset-router', dest='router',
                         action='store_false', help="Turns off router mode")
 
+    parser.add_argument('--tunnel',
+                        action='store_true', help="Create a TUN tunnel device for forwarding IP packets over the mesh")
+
     parser.set_defaults(router=None)
 
     parser.add_argument('--version', action='version', version=f"{pkg_resources.require('meshtastic')[0].version}")
@@ -411,7 +419,7 @@ def main():
         if args.info or args.set or args.seturl or args.setowner or args.setlat or args.setlon or \
                 args.settime or \
                 args.setch_longslow or args.setch_shortfast or args.setstr or args.setchan or args.sendtext or \
-                args.router != None or args.qr:
+                args.tunnel or args.router != None or args.qr:
             args.seriallog = "none"  # assume no debug output in this case
         else:
             args.seriallog = "stdout"  # default to stdout

meshtastic/tunnel.py

@@ -0,0 +1,124 @@
+# code for IP tunnel over a mesh
+# Note python-pytuntap was too buggy
+# using pip3 install pytap2
+# make sure to "sudo setcap cap_net_admin+eip /usr/bin/python3.8" so python can access tun device without being root
+# sudo ip tuntap del mode tun tun0
+
+# FIXME: set MTU correctly
+# select local ip address based on nodeid
+# print known node ids as IP addresses
+# change dev name to mesh
+
+from . import portnums_pb2
+from pubsub import pub
+from pytap2 import TapDevice
+import logging
+import threading
+
+"""A list of chatty UDP services we should never accidentally
+forward to our slow network"""
+udpBlacklist = {
+    1900, # SSDP
+    5353, # multicast DNS
+}
+
+"""A list of TCP services to block"""
+tcpBlacklist = {}
+
+"""A list of protocols we ignore"""
+protocolBlacklist = {
+    0x02, # IGMP
+	0x80, # Service-Specific Connection-Oriented Protocol in a Multilink and Connectionless Environment
+}
+
+def hexstr(barray):
+    """Print a string of hex digits"""
+    return ":".join('{:02x}'.format(x) for x in barray)
+
+def ipstr(barray):
+    """Print a string of ip digits"""
+    return ".".join('{}'.format(x) for x in barray)
+
+def readnet_u16(p, offset):
+    """Read big endian u16 (network byte order)"""
+    return p[offset] * 256 + p[offset + 1]
+
+
+
+def onTunnelReceive(packet, interface):
+    """Callback for received tunneled messages from mesh
+    
+    FIXME figure out how to do closures with methods in python"""
+    p = packet["decoded"]["data"]["payload"]
+    logging.debug(f"Received tunnel message")
+
+
+class Tunnel:
+    """A TUN based IP tunnel over meshtastic"""
+    
+    def __init__(self, iface):
+        """
+        Constructor
+
+        iface is the already open MeshInterface instance
+        """
+        self.iface = iface
+
+        logging.info("Starting IP to mesh tunnel (you must be root for this pre-alpha feature to work)")
+
+        pub.subscribe(onTunnelReceive, "meshtastic.receive.data.IP_TUNNEL_APP")
+
+        logging.debug("creating TUN device")
+        self.tun = TapDevice(mtu=200)
+        # tun.create()
+        self.tun.up()
+        self.tun.ifconfig(address="10.115.1.2",netmask="255.255.0.0")
+        logging.debug("starting TUN reader")
+        self._rxThread = threading.Thread(target=self.__tunReader, args=(), daemon=True)
+        self._rxThread.start()
+
+    def __tunReader(self):
+        tap = self.tun
+        logging.debug("TUN reader running")
+        while True:
+            p = tap.read()
+
+            protocol = p[8 + 1]
+            srcaddr = p[12:16]
+            destaddr = p[16:20]
+            subheader = 20
+            ignore = False # Assume we will be forwarding the packet
+            if protocol in protocolBlacklist:
+                ignore = True
+                logging.debug(f"Ignoring blacklisted protocol 0x{protocol:02x}")
+            elif protocol == 0x01: # ICMP
+                logging.debug("forwarding ICMP message")
+                # reply to pings (swap src and dest but keep rest of packet unchanged)
+                #pingback = p[:12]+p[16:20]+p[12:16]+p[20:]
+                #tap.write(pingback)
+            elif protocol == 0x11: # UDP
+                srcport = readnet_u16(p, subheader)
+                destport = readnet_u16(p, subheader + 2)
+                logging.debug(f"udp srcport={srcport}, destport={destport}")
+                if destport in udpBlacklist:
+                    ignore = True
+                    logging.debug(f"ignoring blacklisted UDP port {destport}")
+            elif protocol == 0x06: # TCP
+                srcport = readnet_u16(p, subheader)
+                destport = readnet_u16(p, subheader + 2)
+                logging.debug(f"tcp srcport={srcport}, destport={destport}")
+                if destport in tcpBlacklist:
+                    ignore = True
+                    logging.debug(f"ignoring blacklisted TCP port {destport}")
+            else:
+                logging.warning(f"unexpected protocol 0x{protocol:02x}, src={ipstr(srcaddr)}, dest={ipstr(destaddr)}")
+
+            if not ignore:
+                logging.debug(f"Forwarding packet bytelen={len(p)} src={ipstr(srcaddr)}, dest={ipstr(destaddr)}")
+
+    def close(self):
+        self.tun.close()
+
+
+
+

tests/tuntest.py

@@ -1,6 +1,7 @@
 # delete me eventually
 # Note python-pytuntap was too buggy
 # using pip3 install pytap2
+# make sure to "sudo setcap cap_net_admin+eip /usr/bin/python3.8" so python can access tun device without being root
 # sudo ip tuntap del mode tun tun0
 
 # FIXME: set MTU correctly
@@ -28,8 +29,13 @@ protocolBlacklist = {
 }
 
 def hexstr(barray):
+    """Print a string of hex digits"""
     return ":".join('{:02x}'.format(x) for x in barray)
 
+def ipstr(barray):
+    """Print a string of ip digits"""
+    return ".".join('{}'.format(x) for x in barray)
+
 def readnet_u16(p, offset):
     """Read big endian u16 (network byte order)"""
     return p[offset] * 256 + p[offset + 1]
@@ -66,10 +72,10 @@ def readtest(tap):
                 ignore = True
                 logging.debug(f"ignoring blacklisted TCP port {destport}")
         else:
-            logging.warning(f"unexpected protocol 0x{protocol:02x}, srcadddr {hexstr(srcaddr)}")
+            logging.warning(f"unexpected protocol 0x{protocol:02x}, src={ipstr(srcaddr)}, dest={ipstr(destaddr)}")
 
         if not ignore:
-            logging.debug(f"Forwarding packet bytes={hexstr(p)}")
+            logging.debug(f"Forwarding packet bytelen={len(p)} src={ipstr(srcaddr)}, dest={ipstr(destaddr)}")