Merge pull request #844 from spiccinini/babeld-auto-gw-mode

RFC add babeld-auto-gw-mode

packages/babeld-auto-gw-mode/Makefile

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+# Copyright (C) 2021 Santiago Piccinini <spiccinini@altermundi.net>
+#
+# This is free software, licensed under the GNU Affero General Public License v3.
+#
+
+include ../../libremesh.mk
+
+define Package/$(PKG_NAME)
+  SECTION:=utils
+  CATEGORY:=Utilities
+  TITLE:=Babel auto Internet gateway module.
+  MAINTAINER:=Santiago Piccinini <spiccinini@altermundi.net>
+  DEPENDS:=+libubus-lua +watchping +lime-proto-babeld
+  PKGARCH:=all
+endef
+
+
+define Package/$(PKG_NAME)/description
+	Watchping hooks to set babeld Internet automatic announcements.
+endef
+
+$(eval $(call BuildPackage,$(PKG_NAME)))

packages/babeld-auto-gw-mode/Readme.md

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+# babeld-auto-gw-mode
+
+By default babeld will redistribute all the routes installed even if they "don't work". For example
+when the internet provider use DHCP and the service is not working but interface is up, the route is
+installed but not working and babeld will anounce the non working route to the network and also
+this route will be used by this node to route the packets so also all its clients won't have internet.
+
+This package provides a solution using watchping hooks that:
+* on wan OK
+  - adds a route with a special protocol number (7)
+* on wan FAIL
+  - removes the default route with proto 7
+  - changes the metric of the default route to 84831. If other nodes are also gateways their babel
+  redistributable routes will have priority over this route at this node and for that reason the
+  default gateway won't be the local non working connection.
+

packages/babeld-auto-gw-mode/files/etc/hotplug.d/lime-config/babeld-auto-gw.lua

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+#!/usr/bin/lua
+
+local config = require("lime.config")
+local uci = config.get_uci_cursor()
+
+-- Redistribute default routes only if they are of protocol 7.
+-- This routes are installed and removed using watchping.
+
+uci:set("babeld", "default4", "proto", "7")
+uci:set("babeld", "default6", "proto", "7")
+uci:commit("babeld")

packages/babeld-auto-gw-mode/files/etc/watchping/wan-fail.d/babeld-gw

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+#!/usr/bin/lua
+--! Copyright (C) 2021 Santiago Piccinini <spiccinini@altermundi.net>
+--!
+--! This is free software, licensed under the GNU Affero General Public License v3.
+
+local ubus = require "ubus"
+local utils = require "lime.utils"
+
+local NONWORKING_ROUTE_METRIC = 84831
+
+local conn = ubus.connect()
+if not conn then
+    error("Failed to connect to ubus")
+end
+
+local wan4_status = conn:call("network.interface.wan", "status", {})
+local wan_ifc = wan4_status.device
+
+--! Do our best to select only the "original" default route installed. Using grep because
+--! using the dev argument removes the dev part of the ip route output.
+local route = utils.unsafe_shell("ip route show default metric 0 | grep " .. wan_ifc):gsub("\n","")
+
+--! replace the default route with one that has metric NONWORKING_ROUTE_METRIC
+if route ~= '' then
+    os.execute("ip r add " .. route .. " metric " .. tonumber(NONWORKING_ROUTE_METRIC))
+    os.execute("ip r del " .. route)
+end
+
+--! remove the babel redistributable route
+os.execute("ip r del default proto 7")

packages/babeld-auto-gw-mode/files/etc/watchping/wan-ok.d/babeld-gw

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+#!/usr/bin/lua
+--! Copyright (C) 2021 Santiago Piccinini <spiccinini@altermundi.net>
+--!
+--! This is free software, licensed under the GNU Affero General Public License v3.
+
+local ubus = require "ubus"
+local utils = require "lime.utils"
+
+local conn = ubus.connect()
+if not conn then
+    error("Failed to connect to ubus")
+end
+
+local wan4_status = conn:call("network.interface.wan", "status", {})
+local wan_ifc = wan4_status.device
+
+--! change the default route from the nonworking metric value to the working metric value
+local nonworking_route = utils.unsafe_shell("ip route show default metric 84831 | grep " .. wan_ifc):gsub("\n","")
+if nonworking_route ~= '' then
+    os.execute("ip r add " .. nonworking_route .. " metric 0")
+    os.execute("ip r del " .. nonworking_route .. " metric 84831")
+end
+
+--! install a route with proto value 7 that will be redistributed by babeld
+for _, route4 in ipairs(wan4_status.route) do
+    if route4.target == "0.0.0.0" and route4.mask == 0 then
+        local r = ("ip r add default via " .. route4.nexthop .. " dev " .. wan4_status.device .. " proto 7 metric 10")
+        os.execute(r)
+    end
+end