ffh-check-connection: initial commit

This commit adds a new package which can be used for scheduled
connectivity checks.

ffh-check-connection/LICENSE

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+Copyright (c) 2021, Freifunk Hannover <info@hannover.freifunk.net>
+Copyright (c) 2013-2021, Project Gluon
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  1. Redistributions of source code must retain the above copyright notice,
+     this list of conditions and the following disclaimer.
+  2. Redistributions in binary form must reproduce the above copyright notice,
+     this list of conditions and the following disclaimer in the documentation
+     and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

ffh-check-connection/Makefile

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+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=ffh-check-connection
+PKG_VERSION:=1
+PKG_RELEASE:=1
+
+include $(TOPDIR)/../package/gluon.mk
+
+define Package/$(PKG_NAME)
+  TITLE:=Helper script to do ping checks with configurable IPv6 targets
+  DEPENDS:=+gluon-core +libgluonutil +gluon-site +luaposix +luabitop +micrond @GLUON_MULTIDOMAIN
+endef
+
+define Package/$(PKG_NAME)/description
+  Script to check when there is connectivity to configurable targets
+  possible using ICMP IPv6 pings. This script will be executed every
+  minute by ``micrond``. If e.g. the connection state changes it
+  executes corresponding commands in a configurable manner.
+endef
+
+$(eval $(call BuildPackageGluon,$(PKG_NAME)))

ffh-check-connection/README.md

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+ffh-check-connection
+====================
+
+This package adds a script that checks if at least one connection to IPv6 hosts
+defined as *target groups* is working using the ping command. 
+The script is called once every minute by ``micrond``.
+For example one can define a group of *local* targets to check if a connection
+to hosts in the mesh network is possible (e.g. time or update servers) and 
+*global* targets for checking if a connection to the global internet is possible.
+Currently only IPv6 addresses are supported.
+This packages is e.g. being used by *ffh-wifi-offline-ssid*.
+
+domain.conf
+-----------
+
+Target groups can be pre-defined in the domain config.
+
+::
+
+    ffh_check_connection = {
+        targets = {
+	    targets_local = {
+                'fe80::dead:c0de:1',
+                'fe80::bad:c0de:1',
+                'fe80::dead:c0de:2',
+                'fe80::bad:c0de:2',
+            },
+            targets_global = {
+                '2620:0:ccc::2', -- OpenDNS
+                '2001:4860:4860::8888', -- Google DNS
+                '2600::1', -- Sprint DNS
+                '2620:0:ccd::2', -- OpenDNS
+                '2001:4860:4860::8844', -- Google DNS
+                '2600::2', -- Sprint DNS
+            },
+	},
+    },
+
+
+Defining target groups in the domain.conf will overwrite existing ones with the same
+name when performing a *sysupgrade* or by triggering *gluon-reconfigure*.
+
+Configuration via UCI
+---------------------
+
+Packages can use ffh-check-connection to be triggered after connection checks.
+For this they can define the following *script* attributes:
+
+script : an entry for defining the ping target
+    enabled : 
+        - a boolean defining whether the script will be considered
+    interval :
+        - the interval to execute the trigger script (in minutes - defaults to 1)
+    command :
+        - the command to execute
+    groups :
+        - the array of target groups on which the ping test will be performed on
+    onchange :
+        - if set true the command is only being executed on a state change or always otherwise
+    trigger :
+        - on which the command is being executed (``offline``, ``online`` or unset for both)
+
+
+*target* groups can be defined with the following attributes:
+
+target : an entry for defining the IPv6 address to ping
+    hosts :
+        - array containing the IPv6 addresses to perform the ping test on
+

ffh-check-connection/check_site.lua

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+local function check_target(t)
+	need_string_array_match(t, '^[%x:]+$', false)
+end
+
+need_table(in_domain({'ffh_check_connection', 'targets'}), check_target, false)

ffh-check-connection/files/usr/lib/micron.d/ffh-check-connection

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+* * * * * /usr/sbin/ffh-check-connection

ffh-check-connection/luasrc/lib/gluon/upgrade/500-ffh-check-connection

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+#!/usr/bin/lua
+
+local uci = require('simple-uci').cursor()
+local site = require 'gluon.site'
+
+for group, hosts in pairs(site.ffh_check_connection.targets()) do
+	uci:delete('ffh-check-connection', 'target', group)
+	uci:section('ffh-check-connection', 'target', group, {
+		hosts = hosts
+	})
+end
+
+uci:save('ffh-check-connection')

ffh-check-connection/luasrc/usr/sbin/ffh-check-connection

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+#!/usr/bin/lua
+
+local bit = require('bit')
+local fcntl = require('posix.fcntl')
+local unistd = require 'posix.unistd'
+local util = require 'gluon.util'
+local uci = require('simple-uci').cursor()
+
+-- Minimal uptime (in minutes) before the checks start
+local min_uptime = 5
+
+local offline_file_prefix = '/tmp/ffh-offline-'
+local firstrun_file = '/tmp/ffh-check-connection-firstrun'
+local lastrun_file = '/tmp/ffh-check-connection-lastrun'
+local lockfile = '/var/lock/ffh-check-connection.lock'
+
+local function readnumber(file)
+	return tonumber(util.readfile(file))
+end
+
+local function writenumber(file, num)
+	io.open(file, "w"):write(tostring(math.floor(num)))
+end
+
+local function shuffle(tbl)
+	new_tbl = {}
+	for i, ele in ipairs(tbl) do
+		table.insert(new_tbl, math.random(1, #new_tbl+1), ele)
+	end
+
+	return new_tbl
+end
+
+local function ping_hosts(hosts)
+	for _, host in ipairs(hosts) do
+		if 0 == os.execute("ping -c 1 -w 10 " .. host) then
+			return true
+		end
+	end
+
+	return false
+end
+
+local function check_connection(group, old_state, hosts)
+	local offline_file = offline_file_prefix .. group
+	local targets = shuffle(hosts)
+
+	if ping_hosts(targets) then
+		if not old_state then
+			util.log(group .. 'connectivity available again')
+			os.remove(offline_file)
+		end
+
+		return true
+	end
+
+	if old_state then
+		util.log(group .. ' connectivity lost')
+		writenumber(offline_file, (util.get_uptime() / 60))
+	end
+
+	return false
+end
+
+local lockfd, err = fcntl.open(lockfile, bit.bor(fcntl.O_WRONLY, fcntl.O_CREAT), 384) -- mode 0600
+
+if not lockfd then
+	util.log(err, true)
+	os.exit(1)
+end
+
+local ok, _ = fcntl.fcntl(lockfd, fcntl.F_SETLK, {
+	l_start = 0,
+	l_len = 0,
+	l_type = fcntl.F_WRLCK,
+	l_whence = unistd.SEEK_SET,
+})
+
+if not ok then
+	io.stderr:write(string.format(
+		"Unable to lock file %s. Make sure there is no other instance running.\n",
+		lockfile
+	))
+	os.exit(1)
+end
+
+local uptime = math.floor(util.get_uptime() / 60)
+
+if uptime < min_uptime then
+	os.exit(0)
+end
+
+math.randomseed(uptime)
+
+local firstrun = uptime
+local lastrun = uptime
+if unistd.access(firstrun_file) and unistd.access(lastrun_file) then
+	firstrun = readnumber(firstrun_file)
+	lastrun = readnumber(lastrun_file)
+else
+	writenumber(firstrun_file, uptime)
+end
+
+local runtime = lastrun - firstrun
+
+local scripts = {}
+uci:foreach('ffh-check-connection', 'script', function(script)
+	if not script['enabled'] then return end
+
+	if not runtime or uptime - lastrun >= (tonumber(script['interval']) or 1) then
+		table.insert(scripts, script)
+	end
+end)
+
+local groups = {}
+uci:foreach('ffh-check-connection', 'target', function(group)
+	-- do not perform connection checks for groups which are not in use
+	for _, script in ipairs(scripts) do
+		if util.contains(script['groups'], group['.name']) then
+			groups[group['.name']] = group['hosts']
+			break
+		end
+	end
+end)
+
+local old_states = {}
+for group, _ in pairs(groups) do
+	if unistd.access(offline_file_prefix .. group) then
+		old_states[group] = false
+	else
+		old_states[group] = true
+	end
+end
+
+local states = {}
+for group, hosts in pairs(groups) do
+	states[group] = check_connection(group, old_states[group], hosts)
+end
+
+for _, script in ipairs(scripts) do
+	local state_changed = false
+	local state_offline = false
+	local state_online = false
+
+	for _, group in ipairs(script['groups']) do
+		if nil ~= states[group] then
+			if states[group] ~= old_states[group] then
+				state_changed = true
+			end
+
+			if states[group] then
+				state_online = true
+			else
+				state_offline = true
+			end
+		end
+	end
+
+	if not runtime or state_changed or not script['onchange'] then
+		local do_run = not script['trigger']
+
+		if script['trigger'] == 'online' and state_online then
+			do_run = true
+		end
+
+		if script['trigger'] == 'offline' and state_offline then
+			do_run = true
+		end
+
+		if do_run then
+			util.exec(script['command'])
+		end
+	end
+end
+
+writenumber(lastrun_file, (util.get_uptime() / 60))