Add dhcp_server_utils. Use Kea DHCP server when installed

scripts/lua/modules/dhcp_server_utils.lua

@@ -0,0 +1,104 @@
+--
+-- (C) 2013-24 - ntop.org
+--
+
+local sys_utils = require "sys_utils"
+
+local dhcp_enabled_key = "ntopng.nedge.dhcp.kea.enabled"
+
+local dhcp_server_utils = {}
+
+-- ###############################################################
+
+-- Cached module (check once)
+local cached_module = nil
+
+-- ###############################################################
+
+-- @brief Check if a systemd service exists
+-- @param service_name The name of the systemd service
+-- @return true if the service exists, false otherwise
+local function serviceExists(service_name)
+  local cmd = "systemctl list-unit-files " .. service_name .. ".service 2>/dev/null | grep -q " .. service_name
+  local result = sys_utils.execShellCmd(cmd .. " && echo 'exists'")
+  return not isEmptyString(result)
+end
+
+-- Detect which DHCP server is available on the system and return
+-- the appropriate DHCP server module (kea_dhcp_server or dhcp_server_utils)
+function dhcp_server_utils.getDhcpServerHandler()
+  if cached_module then
+    return cached_module
+  end
+
+  local kea_service = "kea-dhcp4-server"
+  local isc_service = "isc-dhcp-server"
+
+  -- Check if kea-dhcp4-server systemd service exists
+  local kea_exists = serviceExists(kea_service)
+
+  if kea_exists then
+    traceError(TRACE_INFO, TRACE_CONSOLE, "Using Kea DHCP server")
+    cached_module = require "conf_handlers.kea_dhcp_server"
+  else
+    traceError(TRACE_INFO, TRACE_CONSOLE, "Using ISC DHCP server")
+    cached_module = require "conf_handlers.dhcp_server_utils"
+  end
+
+  return cached_module
+end
+
+-- ###############################################################
+
+-- This function is used to check if the DHCP server status is up
+-- and if not, restart it.
+function dhcp_server_utils.checkRestartDHCPService()
+  if ntop.isnEdge() then
+    local dhcp_handler = dhcp_server_utils.getDhcpServerHandler()
+    if (ntop.getCache(dhcp_enabled_key) or '0') == '1' then
+      if not sys_utils.isActiveService(dhcp_handler.service_name) then
+        sys_utils.restartService(dhcp_handler.service_name)
+      end
+    end
+  end
+end
+
+-- ###############################################################
+
+-- This function is used to start the DHCP server
+function dhcp_server_utils.startDHCPService()
+  if ntop.isnEdge() then
+    local dhcp_handler = dhcp_server_utils.getDhcpServerHandler()
+    ntop.setCache(dhcp_enabled_key, '1')
+    sys_utils.enableService(dhcp_handler.service_name)
+    sys_utils.restartService(dhcp_handler.service_name)
+  end
+end
+
+-- ###############################################################
+
+-- This function is used to stop the DHCP server
+function dhcp_server_utils.stopDHCPService()
+  if ntop.isnEdge() then
+    local dhcp_handler = dhcp_server_utils.getDhcpServerHandler()
+    ntop.setCache(dhcp_enabled_key, '0')
+    sys_utils.disableService(dhcp_handler.service_name)
+    sys_utils.stopService(dhcp_handler.service_name)
+  end
+end
+
+-- ###############################################################
+
+-- @brief Write DHCP server configuration
+-- @param dhcp_config The DHCP server configuration table
+-- @param all_interfaces Table mapping interface names to roles (lan/wan)
+-- @param dns_config The DNS configuration table with global and secondary DNS
+-- @return true on success, false on error
+function dhcp_server_utils.writeDhcpServerConfiguration(dhcp_config, all_interfaces, dns_config)
+  local dhcp_handler = dhcp_server_utils.getDhcpServerHandler()
+  return dhcp_handler.writeDhcpServerConfiguration(dhcp_config, all_interfaces, dns_config)
+end
+
+-- ###############################################################
+
+return dhcp_server_utils