gluon-mesh-vpn: fix fastd <-> tunneldigger migration

The generic upgrade script is moved to run after the more specific scripts.
In addition, the script will now remove the configuration sections of
uninstalled VPN packages, so both positive and negative changes of the
default enable state can be migrated correctly.

Based-on-patch-by: Cyrus Fox <cyrus@lambdacore.de>
Fixes: #1187

package/gluon-mesh-vpn-core/luasrc/lib/gluon/upgrade/400-mesh-vpn → package/gluon-mesh-vpn-core/luasrc/lib/gluon/upgrade/500-mesh-vpn

@@ -62,15 +62,36 @@ uci:save('firewall')
 
 -- VPN migration
 local has_fastd = fs.access('/lib/gluon/mesh-vpn/fastd')
-local fastd_enabled = uci:get_bool("fastd", "mesh_vpn", "enabled")
+local fastd_enabled = uci:get('fastd', 'mesh_vpn', 'enabled')
 
 local has_tunneldigger = fs.access('/lib/gluon/mesh-vpn/tunneldigger')
-local tunneldigger_enabled = uci:get_bool("tunneldigger", "mesh_vpn", "enabled")
-
-local enabled = fastd_enabled or tunneldigger_enabled or false
+local tunneldigger_enabled = uci:get('tunneldigger', 'mesh_vpn', 'enabled')
+
+local enabled
+
+-- If the installed VPN package has its enabled state set, keep the value
+if has_fastd and fastd_enabled then
+	enabled = fastd_enabled == '1'
+elseif has_tunneldigger and tunneldigger_enabled then
+	enabled = tunneldigger_enabled == '1'
+-- Otherwise, migrate the other package's value if any is set
+elseif fastd_enabled or tunneldigger_enabled then
+	enabled = fastd_enabled == '1' or tunneldigger_enabled == '1'
+-- If nothing is set, use the default
+else
+	enabled = site.mesh_vpn.enabled or false
+end
 
-uci:set("fastd", "mesh_vpn", "enabled", has_fastd and enabled)
-uci:save("fastd")
+if has_fastd then
+	uci:set('fastd', 'mesh_vpn', 'enabled', enabled)
+else
+	uci:delete('fastd', 'mesh_vpn')
+end
+uci:save('fastd')
 
-uci:set("tunneldigger", "mesh_vpn", "enabled", has_tunneldigger and enabled)
-uci:save("tunneldigger")
+if has_tunneldigger then
+	uci:set('tunneldigger', 'mesh_vpn', 'enabled', enabled)
+else
+	uci:delete('tunneldigger', 'mesh_vpn')
+end
+uci:save('tunneldigger')

package/gluon-mesh-vpn-fastd/luasrc/lib/gluon/upgrade/400-mesh-vpn-fastd

@@ -6,11 +6,6 @@ local util = require 'gluon.util'
 local uci = require('simple-uci').cursor()
 
 
-local enabled = uci:get('fastd', 'mesh_vpn', 'enabled')
-if enabled == nil then
-	enabled = site.mesh_vpn.enabled or false
-end
-
 local syslog_level = uci:get('fastd', 'mesh_vpn', 'syslog_level') or 'verbose'
 
 local methods
@@ -40,7 +35,6 @@ end
 
 
 uci:section('fastd', 'fastd', 'mesh_vpn', {
-	enabled = enabled,
 	group = 'gluon-mesh-vpn',
 	syslog_level = syslog_level,
 	interface = 'mesh-vpn',

package/gluon-mesh-vpn-tunneldigger/luasrc/lib/gluon/upgrade/400-mesh-vpn-tunneldigger

@@ -6,18 +6,17 @@ local util = require 'gluon.util'
 local uci = require('simple-uci').cursor()
 
 
-local enabled = uci:get('tunneldigger', 'mesh_vpn', 'enabled')
-if enabled == nil then
-	if uci:get_first('tunneldigger', 'broker', 'interface') == "mesh-vpn" then
+local enabled
+
+-- Delete old broker config section (remove in 2019)
+if not uci:get('tunneldigger', 'mesh_vpn') then
+	if uci:get_first('tunneldigger', 'broker', 'interface') == 'mesh-vpn' then
 		enabled = uci:get_first('tunneldigger', 'broker', 'enabled')
 	end
-end
-if enabled == nil then
-	enabled = site.mesh_vpn.enabled or false
-end
 
--- Delete old broker config section
-if not uci:get('tunneldigger', 'mesh_vpn') then
+	-- In the usual case (no migration from old tunneldigger package), the
+	-- enabled state is set in the 500-mesh-vpn script
+
 	uci:delete_all('tunneldigger', 'broker')
 end