[fix] Store full backup of default UCI files

Without this patch, OpenWISP will not store
complete UCI files when overwriting them.

This causes the removal of important UCI options
when templates are removed.

openwisp-config/files/sbin/openwisp-update-config.lua

@@ -38,8 +38,9 @@ local get_standard = function() return uci.cursor(standard_config_dir) end
 local get_remote = function()
   return uci.cursor(remote_config_dir, '/tmp/openwisp/.uci')
 end
-local get_check =
-  function() return uci.cursor(check_config_dir, '/tmp/openwisp/.uci') end
+local get_check = function()
+  return uci.cursor(check_config_dir, '/tmp/openwisp/.uci')
+end
 local get_stored = function()
   return uci.cursor(stored_config_dir, '/tmp/openwisp/.uci')
 end
@@ -153,34 +154,9 @@ if lfs.attributes(remote_config_dir, 'mode') == 'directory' then
     if lfs.attributes(remote_path, 'mode') == 'file' then
       -- if there's no backup of the file yet, create one
       if not utils.file_exists(stored_path) then
-        os.execute('cp ' .. standard_path .. ' ' .. stored_path)
-        local uci_sections = stored:get_all(file) or {}
-        for key, section in pairs(uci_sections) do
-          -- check if section is in remote configuration
-          local section_check = check:get(file, section['.name'])
-          if section_check then
-            -- check if options is in remote configuration
-            for option, value in pairs(section) do
-              if not utils.starts_with_dot(option) then
-                local option_check = check:get(file, section['.name'], option)
-                if option_check then
-                  -- if option is in remote configuration, remove it
-                  stored:delete(file, section['.name'], option)
-                end
-              end
-            end
-            -- remove entire section if empty
-            local result = stored:get_all(file, section['.name'])
-            if result and utils.is_uci_empty(result) then
-              stored:delete(file, section['.name'])
-            end
-          end
-        end
-        stored:commit(file)
-        -- remove uci file if empty
-        local uci_file = stored:get_all(file)
-        if uci_file and utils.is_table_empty(uci_file) then
-          os.remove(stored_path)
+        local uci_file = check:get_all(file)
+        if uci_file and not utils.is_table_empty(uci_file) then
+          os.execute('cp ' .. standard_path .. ' ' .. stored_path)
         end
       end
       -- MERGE mode

openwisp-config/tests/test_update_config.lua

@@ -24,6 +24,7 @@ TestUpdateConfig = {
         os.execute('cp ./update/system '..config_dir..'system')
         os.execute('cp ./update/network '..config_dir..'network')
         os.execute('cp ./update/wireless '..config_dir..'wireless')
+        os.execute('cp ./update/firewall '..config_dir..'firewall')
         -- we expect these UCI files to be removed
         os.execute('cp ./config/wireless-autoname '..remote_config_dir..'/wireless-autoname')
         os.execute('cp ./wifi/wireless '..remote_config_dir..'/wireless')
@@ -65,11 +66,16 @@ function TestUpdateConfig.test_update()
     local storedNetworkFile = io.open(stored_dir .. '/etc/config/network')
     luaunit.assertNotNil(storedNetworkFile)
     local storedNetworkContents = storedNetworkFile:read('*all')
-    -- ensure wg1 is not added that is downloaded from remote
-    luaunit.assertNil(string.find(storedNetworkContents, "config interface 'wg1'"))
-    -- ensure wan and wg0 are present
+    -- ensure stored
+    luaunit.assertNotNil(string.find(storedNetworkContents, "config interface 'wg1'"))
     luaunit.assertNotNil(string.find(storedNetworkContents, "config interface 'wan'"))
     luaunit.assertNotNil(string.find(storedNetworkContents, "config interface 'wg0'"))
+    -- ensure only options with differing values are stored
+    local storedFirewallFile = io.open(stored_dir .. '/etc/config/firewall')
+    luaunit.assertNotNil(storedFirewallFile)
+    local storedFirewallContents = storedFirewallFile:read('*all')
+    luaunit.assertNotNil(string.find(storedFirewallContents, "option forward 'REJECT'"))
+    luaunit.assertNotNil(string.find(storedFirewallContents, "option output 'ACCEPT'"))
     -- check system
     local systemFile = io.open(config_dir .. 'system')
     luaunit.assertNotNil(systemFile)

openwisp-config/tests/update/firewall

@@ -0,0 +1,5 @@
+config defaults 'defaults'
+  option syn_flood '1'
+  option input 'ACCEPT'
+  option output 'ACCEPT'
+  option forward 'REJECT'