set gateway mode automatically

Added arg and config option to manually set gw_mode.
When gateway_mode is auto, a temporary config will be added, and after a
ten sec delay, naxalnet will check if systemd-networkd shows a
'routable' connection. If the connection is routable, gw_mode will be
set to server; or client otherwise.

naxalnet.conf.example

@@ -12,9 +12,18 @@ confdir = /usr/share/naxalnet/networkd
 runtimedir = /run/systemd/network
 
 [device]
+# These are better left this way
+# Changing this won't do you any good, unless you have
+# other network configs that would mess things up.
 batman=bat0
 bridge=bridge0
 
+[gateway]
+# This helps users choose the best network when multiple machines
+# offer an internet connection, or to be more precise, a DHCP server
+# Allowed values: auto, server, client or off
+mode=auto
+
 [adhoc]
 # All your nodes should have the same name
 name = NxMesh

naxalnet/__init__.py

@@ -35,4 +35,4 @@ See README.md for documentation.
 #
 # In case you forgot to change the version, skip the number
 # and put the next number in the next commit.
-__version__ = "0.4.0a5.dev1"
+__version__ = "0.4.0a5.dev2"

naxalnet/config.py

@@ -170,6 +170,12 @@ def parse_args() -> Namespace:
         help="name of bridge interface",
     )
 
+    parser.add_argument(
+        "--gateway-mode",
+        default=config["gateway"]["mode"],
+        help="auto, server, client, or off",
+    )
+
     parser.add_argument(
         "--version",
         "-V",

naxalnet/default.py

@@ -34,6 +34,7 @@ CONFIG = {
     "device": {"batman": "bat0", "bridge": "bridge0"},
     "adhoc": {"name": "NxMesh"},
     "ap": {"ssid": "MeshWiFi", "passwd": "naxalnet256"},
+    "gateway": {"mode": "auto"},
 }
 
 # glob

naxalnet/network.py

@@ -40,7 +40,10 @@ class NetworkD:
         self.variables = {}
         print(runtime_dir)
         self.runtime_path = Path(runtime_dir)
-        print(self.runtime_path)
+        # Create the runtime directory if it doesn't exist
+        self.runtime_path.mkdir(parents=True, exist_ok=True)
+
+        # print(self.runtime_path)
 
     def set_vars(self, **variables):
         """set the variables to replace with str.format"""
@@ -65,8 +68,27 @@ class NetworkD:
         print(self.runtime_path / name)
         destination.write_text(text, encoding="utf-8")
         self.reload()
-        self.files.append(name)
+        # This allows to delete all configs later
+        self.files.append(destination.name)
 
     def is_routable(self) -> bool:
         """returns true if any interface is routable"""
         return self.proxy.AddressState == "routable"
+
+    def remove_config(self, name: str) -> None:
+        """
+        remove the file called 'name' from the runtime dir and reload
+        """
+        path = self.runtime_path / name
+        path.unlink()
+        self.reload()
+
+    def remove_all_configs(self) -> None:
+        """
+        Remove all configs added by add_config().
+        The configs will be removed only if they were added in the same
+        instance of NetworkD, that is, only files in self.files will be
+        removed.
+        """
+        for i in self.files:
+            self.remove_config(i)

naxalnet/scripts.py

@@ -27,6 +27,7 @@ When run from the commandline, the function main() is called.
 """
 
 import sys
+import time
 from pathlib import Path
 from dasbus.error import DBusError
 from systemd.daemon import notify
@@ -53,17 +54,39 @@ def get_sorted_glob(directory: str, glob: str):
     return sorted_list
 
 
-def setup_mesh():
-    """configure networkd to setup the mesh"""
+def any_interface_is_routable():
+    """returns true if any of the interfaces is routable"""
+    networkd = NetworkD(runtime_dir=args.networkd_runtime_dir)
+
+    # First, add the temporary configs to networkd.
+    for i in get_sorted_glob(args.networkd_config_dir, TMP_NET_GLOB):
+        logger.debug("Adding temporary config %s", i)
+        networkd.add_config(i)
+    # Then, wait for some time to setup the network
+    time.sleep(10)
+    routable = networkd.is_routable()
+    networkd.remove_all_configs()
+
+    return routable
+
+
+def setup_mesh(gateway_mode: str = "off"):
+    """
+    configure networkd to setup the mesh
+
+    gateway_mode can be client, server, or off
+    """
     try:
         notify("STATUS=Configuring the network...")
         logger.info("Copying network config files")
         dest = Path(args.networkd_runtime_dir)
-        # Create the volatile directory if it doesn't exist
-        dest.mkdir(parents=True, exist_ok=True)
 
         networkd = NetworkD(runtime_dir=args.networkd_runtime_dir)
-        networkd.set_vars(batdev=args.batman_device, bridgedev=args.bridge_device)
+        networkd.set_vars(
+            batdev=args.batman_device,
+            bridgedev=args.bridge_device,
+            gateway_mode=gateway_mode,
+        )
         for i in get_sorted_glob(args.networkd_config_dir, MESH_GLOB):
             logger.debug("Adding network config %s", i)
             networkd.add_config(i)
@@ -184,6 +207,22 @@ def main():
     # Notify systemd that naxalnet is ready.
     # see man:sd_notify(3)
     notify("READY=1")
+
+    if args.gateway_mode == "auto":
+        logger.info("Checking for internet connection")
+        notify("STATUS=Checking for internet")
+        # If any interface is routable, set gateway mode to server
+        if any_interface_is_routable():
+            gateway_mode = "server"
+        else:
+            gateway_mode = "client"
+        logger.info("gateway_mode set to %s", gateway_mode)
+    elif args.gateway_mode in ["server", "client", "off"]:
+        gateway_mode = args.gateway_mode
+    else:
+        logger.error("gateway-mode has an illegal value")
+        exit(5)
+
     setup_devices()
     setup_mesh()
 

systemd-networkd/mesh.01-batman.netdev

@@ -5,6 +5,6 @@ Name={batdev}
 Description=BATMAN interface
 Kind=batadv
 
-# Use default settings. Uncomment to change
 # see man:systemd.netdev(5) § [BATMANADVANCED] SECTION OPTIONS
-#[BatmanAdvanced]
+[BatmanAdvanced]
+GatewayMode={gateway_mode}