Implement remote assistance

- It enables a VPN via n2n
- Remote assistance will be automatically disabled after 1 day
- Optionally it's possible to give admin access to the support

scripts/lua/modules/os_utils.lua

@@ -5,8 +5,11 @@
 local dirs = ntop.getDirs()
 
 local os_utils = {}
+local NTOPCTL_CMD = "sudo ntopctl"
+local NTOPNG_CONFIG_TOOL = "/usr/bin/ntopng-utils-manage-config"
+local is_windows = ntop.isWindows()
 
--- #################################
+-- ########################################################
 
 function os_utils.getPathDivider()
    if(ntop.isWindows()) then
@@ -16,7 +19,7 @@ function os_utils.getPathDivider()
    end
 end
 
--- #################################
+-- ########################################################
 
 -- Fix path format Unix <-> Windows
 function os_utils.fixPath(path)
@@ -29,7 +32,124 @@ function os_utils.fixPath(path)
   return(path)
 end
 
--- #################################
+-- ########################################################
+
+--! @brief Execute a system command and return its output
+--! @return the pair (output, ret_code). output will be nil on error.
+--! @note error condition is determined from the command exit status
+--! @note redirect the stderr of the command if the command is expected to fail
+function os_utils.execWithOutput(c, ret_code_success)
+   if is_windows then
+      return nil
+   end
+
+   local f = assert(io.popen(c, 'r'))
+   ret_code_success = ret_code_success or 0
+  
+   local s = assert(f:read('*a'))
+   local rv = {f:close()}
+   local retcode = rv[3]
+
+   if retcode ~= ret_code_success then
+      return nil, retcode
+   end
+
+   return s, retcode
+end
+
+-- ########################################################
+
+local function ntopctl_cmd(service_name, ...)
+   local cmd = {NTOPCTL_CMD, service_name, ...}
+   return table.concat(cmd, " ") .. " 2>/dev/null"
+end
+
+--! @brief Execute service control tool and get its output.
+--! @return Command output. See os_utils.execWithOutput for details.
+function os_utils.ntopctlCmd(service_name, ...)
+   return os_utils.execWithOutput(ntopctl_cmd(service_name, ...))
+end
+
+-- ########################################################
+
+--! @brief Check if a service is available into the system.
+--! @return true if service is available, false otherwise.
+function os_utils.hasService(service_name, ...)
+   if not ntop.exists(NTOPNG_CONFIG_TOOL) then
+      return false
+   end
+
+   return(os_utils.execWithOutput(ntopctl_cmd(service_name, "has-service", ...)) == "yes")
+end
+ 
+-- ########################################################
+
+--! @brief Enable a service
+--! @return true if service was enabled successfully, false otherwise
+function os_utils.enableService(service_name, ...)
+   os_utils.execWithOutput(ntopctl_cmd(service_name, "enable", ...))
+   return os_utils.isEnabled(service_name)
+end
+
+-- ########################################################
+
+--! @brief Disable a service
+--! @return true if service was disabled successfully, false otherwise
+function os_utils.disableService(service_name, ...)
+   os_utils.execWithOutput(ntopctl_cmd(service_name, "disable", ...))
+   return not os_utils.isEnabled(service_name)
+end
+
+-- ########################################################
+
+--! @brief Restart a service
+--! @note See os_utils.execWithOutput for return value
+function os_utils.restartService(service_name, ...)
+   os_utils.execWithOutput(ntopctl_cmd(service_name, "restart", ...))
+   return(os_utils.serviceStatus(service_name) == "active")
+end
+
+-- ########################################################
+
+--! @brief Stop a service
+--! @note See os_utils.execWithOutput for return value
+function os_utils.stopService(service_name, ...)
+   os_utils.execWithOutput(ntopctl_cmd(service_name, "stop", ...))
+   return(os_utils.serviceStatus(service_name) == "inactive")
+end
+
+-- ########################################################
+
+--! @brief Check the service status.
+--! @return active|inactive|error
+function os_utils.serviceStatus(service_name, ...)
+   local rv = os_utils.execWithOutput(ntopctl_cmd(service_name, "is-active", ...))
+
+   if rv == "active\n" then
+      return "active"
+   elseif rv == "inactive\n" then
+      return "inactive"
+   else
+      return "error"
+   end
+end
+ 
+-- ########################################################
+
+--! @brief Check if the service is active
+--! @return true if service is active, false otehrwise
+function os_utils.isActive(service_name, ...)
+  return(os_utils.serviceStatus(service_name, ...) == "active")
+end
+
+-- ########################################################
+
+function os_utils.isEnabled(service_name, ...)
+   local rv = os_utils.execWithOutput(ntopctl_cmd(service_name, "is-enabled", ...))
+   return(rv == "enabled")
+end
+
+-- ########################################################
 
 return os_utils