ffh-wifi-offline-ssid: initial commit

This commit adds a package to change the SSID if no internet connection is
available. It depends on ffh-check-connection.

This is based on freifunk-gluon/gluon#1649

ffh-wifi-offline-ssid/LICENSE

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+Copyright (c) 2021, Freifunk Hannover <[email protected]>
+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-wifi-offline-ssid/Makefile

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+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=ffh-wifi-offline-ssid
+PKG_VERSION:=1
+PKG_RELEASE:=1
+
+include $(TOPDIR)/../package/gluon.mk
+
+define Package/$(PKG_NAME)
+  TITLE:=Changes the SSID to an Offline-SSID on disrupted internet connection
+  DEPENDS:=+gluon-core +ffh-check-connection
+endef
+
+define Package/$(PKG_NAME)/description
+  Script to change the SSID to an Offline-SSID when there is no connection to
+  the internet. This SSID can be generated from the node's hostname with the
+  first and last part of the node's name or from the MAC address.
+  The script is being triggered by ffh-check-connection on connection status
+  changes.
+endef
+
+$(eval $(call BuildPackageGluon,$(PKG_NAME)))

ffh-wifi-offline-ssid/README.md

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+ffh-wifi-offline-ssid
+=====================
+
+This package adds a script which changes the WLAN SSID on loss of
+internet connectivity. It depends on and is being called by
+*ffh-check-connection*.
+
+This ``offline SSID`` can be generated from the node's hostname
+with the first and last part of the node name or the MAC address.
+
+After the connection has been lost for a certain ``threshold`` of
+minutes it is being changed to the offline SSID.
+Once the connectivity is established it will be changed back to
+the default SSID again.
+
+domain.conf
+-----------
+
+Adapt and add this block to your ``domain.conf``:
+
+::
+
+    ffh_wifi_offline_ssid = {
+      disabled = false,
+      target_group = 'targets_global',  -- the ffh-check-connection target group to perform tests on
+      threshold = 5,                    -- the number of minutes after which connectivity is considered lost 
+      prefix = 'Offline_',              -- use something short to leave space for the hostname (no '~' allowed!)
+      suffix = 'hostname',              -- generate the SSID with either 'hostname', 'mac' or only the prefix: 'none'
+    },
+
+
+Configuration via UCI
+---------------------
+
+You can configure the offline SSID on the command line with ``uci``. 
+E.g. disable it with:
+
+::
+
+    uci set ffh-wifi-offline-ssid.settings.disabled='1'
+
+Or set the threshold to three minutes with
+
+::
+
+    uci set ffh-wifi-offline-ssid.settings.threshold='3'

ffh-wifi-offline-ssid/check_site.lua

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+need_boolean({'ffh_wifi_offline_ssid', 'disabled'}, false)
+need_string({'ffh_wifi_offline_ssid', 'target_group'}, true)
+need_number({'ffh_wifi_offline_ssid', 'threshold'}, false)
+need_string({'ffh_wifi_offline_ssid', 'prefix'}, false)
+need_one_of({'ffh_wifi_offline_ssid', 'suffix'}, {'hostname', 'mac', 'none'}, false)

ffh-wifi-offline-ssid/files/etc/config/ffh-wifi-offline-ssid

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+config settings 'settings'

ffh-wifi-offline-ssid/luasrc/lib/gluon/upgrade/600-ffh-wifi-offline-ssid

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+#!/usr/bin/lua
+
+local site = require 'gluon.site'
+local uci = require('simple-uci').cursor()
+
+if site.ffh_wifi_offline_ssid then
+	local site_disabled = site.ffh_wifi_offline_ssid.disabled() or '0'
+
+	uci:section('ffh-wifi-offline-ssid', 'settings', 'settings', {
+		disabled	= uci:get('ffh-wifi-offline-ssid', 'settings', 'disabled') or site_disabled,
+		threshold	= site.ffh_wifi_offline_ssid.threshold() or 5,
+		prefix 		= site.ffh_wifi_offline_ssid.prefix() or 'Offline_',
+		suffix		= site.ffh_wifi_offline_ssid.suffix() or 'hostname',
+	})
+
+	uci:save('ffh-wifi-offline-ssid')
+
+	uci:section('ffh-check-connection', 'script', 'ffh_wifi_offline', {
+		enabled		= true,
+		interval	= 1,
+		command		= 'ffh-wifi-offline-ssid offline',
+		groups		= {site.ffh_wifi_offline_ssid.target_group(),},
+		trigger		= 'offline',
+	})
+
+	uci:section('ffh-check-connection', 'script', 'ffh_wifi_online', {
+		enabled		= true,
+		interval	= 1,
+		command		= 'ffh-wifi-offline-ssid online',
+		groups		= {site.ffh_wifi_offline_ssid.target_group(),},
+		onchange	= true,
+		trigger		= 'online',
+	})
+
+	uci:save('ffh-check-connection')
+end

ffh-wifi-offline-ssid/luasrc/usr/sbin/ffh-wifi-offline-ssid

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+#!/usr/bin/lua
+
+local uci = require('simple-uci').cursor()
+local unistd = require 'posix.unistd'
+local util = require 'gluon.util'
+
+local prog_name = 'ffh-wifi-offline-ssid'
+local offline_file = '/tmp/ffh-offline-ffh_wifi_offline'
+
+local disabled = uci:get('ffh-wifi-offline-ssid', 'settings', 'disabled') or false
+if disabled then
+	print(prog_name .. " is disabled. Exiting...")
+	os.exit(0)
+end
+
+local threshold_mins = tonumber(uci:get(prog_name, 'settings', 'threshold')) or 0
+
+local uptime_mins = math.floor(util.get_uptime() / 60)
+local offline_mins = uptime
+if unistd.access(offline_file) then
+	offline_mins = uptime - (tonumber(util.readfile(offline_file)) or 0)
+end
+
+if arg[1] == "offline" and offline_mins < threshold_mins then
+	print((threshold_mins - offline_mins) .. ' minutes remaining until the node is considered offline. Exiting...')
+	os.exit(0)
+end
+
+local phys = {count = 0}
+uci:foreach('wireless', 'wifi-device', function(config)
+	local phy = util.find_phy(config)
+	if phy then
+		phys[config['.name']] = phy
+		phys['count'] = phys['count'] + 1
+	end
+end)
+
+if phys['count'] == 0 then
+	print('No radios detected. Exiting...')
+	os.exit(0)
+end
+
+local ssids = {}
+uci:foreach('wireless', 'wifi-iface', function(config)
+	if config['mode'] == 'ap' and config['network'] == 'client' and config['ssid'] then
+		table.insert(ssids, {ssid = config['ssid'], phy = phys[config['device']]})
+	end
+end)
+
+if #ssids == 0 then
+	print('No client networks active. Exiting...')
+	os.exit(0)
+end
+
+-- Use something short to leave space for the hostname
+-- (no '~' allowed!)
+local prefix = uci:get(prog_name, 'settings', 'prefix') or 'Offline_'
+
+-- Generate the SSID either with 'hostname', 'mac' or only using the prefix
+local settings_suffix = uci:get(prog_name, 'settings', 'suffix') or 'hostname'
+
+local suffix = ''
+if settings_suffix == 'hostname' then
+	local pretty_hostname = require 'pretty_hostname'
+	suffix = pretty_hostname.get(uci)
+	-- 32 would be possible as well
+	if (string.len(suffix) > 30 - string.len(prefix)) then
+		-- Calculate the length of the first part of the node identifier in the offline-ssid
+		local half = math.floor((28 - string.len(prefix)) / 2)
+		-- Jump to this character for the last part of the name
+		local skip = string.len(suffix) - half
+		-- Use the first and last part of the nodename for nodes with long name
+		suffix = string.sub(suffix, 0, half) .. '...' .. string.sub(suffix, skip)
+	end
+elseif settings_suffix == 'mac' then
+	local sysconfig = require 'gluon.sysconfig'
+	suffix = sysconfig.primary_mac
+end
+
+local offline_ssid = prefix .. suffix
+
+local hup_needed = 0
+local ssid_grep = 'grep "^ssid='
+for _, ssid in ipairs(ssids) do
+	local hostapd = '/var/run/hostapd-' .. ssid.phy .. '.conf'
+
+	if arg[1] == "offline" then
+		old_ssid = ssid.ssid
+		new_ssid = offline_ssid
+	else
+		old_ssid = offline_ssid
+		new_ssid = ssid.ssid
+	end
+
+	if os.execute(ssid_grep .. new_ssid .. '" ' .. hostapd) == 0 then
+		print('Current SSID "' .. new_ssid .. '" for ' .. ssid.phy .. ' is already correct. Skipping...')
+		break
+	end
+
+	-- Confirm that the old SSID was set
+	if os.execute(ssid_grep .. old_ssid .. '" ' .. hostapd) ~= 0 then
+		util.log(prog_name .. ': Warning: Neither found SSID "' .. ssid.ssid .. '" nor "' .. offline_ssid .. '" on ' .. ssid.phy .. '.')
+	end
+
+	local current_ssid = util.trim(util.exec(ssid_grep .. '" ' .. hostapd .. ' | cut -d"=" -f2'))
+
+	util.log(prog_name .. ': Current SSID is "' .. current_ssid .. '". Changing it to "' .. new_ssid .. '"...')
+	os.execute('sed -i "s~^ssid=' .. current_ssid .. '~ssid=' .. new_ssid .. '~" ' .. hostapd)
+	hup_needed = 1
+end
+
+-- Send hup to all hostapd instances to apply the new SSID(s)
+if hup_needed == 1 then
+	print("Applying new SSIDs...")
+	os.execute('killall -hup hostapd')
+end