Add utility module to generate Kea configuration file

scripts/lua/modules/conf_handlers/isc_dhcp_server.lua

@@ -3,6 +3,7 @@
 --
 
 local sys_utils = require "sys_utils"
+
 local service_name = "isc-dhcp-server"
 
 local redis_key = "ntopng.nedge.dhcp.enabled"

scripts/lua/modules/conf_handlers/kea_dhcp_server.lua

@@ -0,0 +1,248 @@
+--
+-- (C) 2013-24 - ntop.org
+--
+
+local sys_utils = require "sys_utils"
+local json = require "dkjson"
+
+local service_name = "kea-dhcp4-server"
+
+local redis_key = "ntopng.nedge.dhcp.kea.enabled"
+
+local kea_dhcp_server = {}
+
+-- ###############################################################
+
+-- Convert netmask to CIDR notation (e.g. 24)
+-- @param netmask The netmask (e.g. 255.255.255.0)
+-- @return The CIDR prefix length
+local function netmask2cidr(netmask)
+  if not netmask then
+    return 32
+  end
+
+  local cidr = 0
+  for octet in string.gmatch(netmask, "%d+") do
+    local num = tonumber(octet)
+    for i = 7, 0, -1 do
+      if bit.band(num, bit.lshift(1, i)) ~= 0 then
+        cidr = cidr + 1
+      else
+        return cidr
+      end
+    end
+  end
+
+  return cidr
+end
+
+-- ###############################################################
+
+-- This function is used to check if the DHCP server status is up
+-- and if not, restart it.
+function kea_dhcp_server.checkRestartDHCPService()
+  if ntop.isnEdge() then
+    if (ntop.getCache(redis_key) or '0') == '1' then
+      if not sys_utils.isActiveService(service_name) then
+        sys_utils.restartService(service_name)
+      end
+    end
+  end
+end
+
+-- ###############################################################
+
+-- This function is used to start the DHCP server
+function kea_dhcp_server.startDHCPService()
+  if ntop.isnEdge() then
+    ntop.setCache(redis_key, '1')
+    sys_utils.enableService(service_name)
+    sys_utils.restartService(service_name)
+  end
+end
+
+-- ###############################################################
+
+-- This function is used to stop the DHCP server
+function kea_dhcp_server.stopDHCPService()
+  if ntop.isnEdge() then
+    ntop.setCache(redis_key, '0')
+    sys_utils.disableService(service_name)
+    sys_utils.stopService(service_name)
+  end
+end
+
+-- ###############################################################
+
+-- Writes the Kea DHCP4 server configuration file in JSON format
+-- @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 kea_dhcp_server.writeDhcpServerConfiguration(dhcp_config, all_interfaces, dns_config)
+  if not dhcp_config or not all_interfaces or not dns_config then
+    traceError(TRACE_ERROR, TRACE_CONSOLE, "Invalid parameters for writeDhcpServerConfiguration")
+    return false
+  end
+
+  local lan_interfaces = {}
+  local subnet4_configs = {}
+  local reservations = {}
+
+  -- Build the list of LAN interfaces and subnet configurations
+  for if_name, role in pairsByKeys(all_interfaces, asc_insensitive) do
+    if (role == "lan") and (dhcp_config["subnet"][if_name]) and (dhcp_config["subnet"][if_name]["enabled"] == "1") then
+      table.insert(lan_interfaces, if_name)
+
+      local lan_dhcp_config = dhcp_config["subnet"][if_name]
+
+      -- Build DNS servers list
+      local dns_servers = {dns_config.global}
+      if not isEmptyString(dns_config.secondary) then
+        table.insert(dns_servers, dns_config.secondary)
+      end
+
+      -- Build subnet configuration
+      local subnet_config = {
+        subnet = lan_dhcp_config["network"] .. "/" .. netmask2cidr(lan_dhcp_config["netmask"]),
+        pools = {
+          {
+            pool = lan_dhcp_config["first_ip"] .. " - " .. lan_dhcp_config["last_ip"]
+          }
+        },
+        ["option-data"] = {
+          {
+            name = "routers",
+            data = lan_dhcp_config["gateway"]
+          },
+          {
+            name = "subnet-mask",
+            data = lan_dhcp_config["netmask"]
+          },
+          {
+            name = "broadcast-address",
+            data = lan_dhcp_config["broadcast"]
+          },
+          {
+            name = "domain-name-servers",
+            data = table.concat(dns_servers, ", ")
+          }
+        },
+        interface = if_name
+      }
+
+      -- Add custom options if present
+      if not isEmptyString(lan_dhcp_config["option_114"]) then
+        table.insert(subnet_config["option-data"], {
+          name = "url",  -- Option 114 (DHCPv4)
+          code = 114,
+          data = lan_dhcp_config["option_114"]
+        })
+      end
+
+      if not isEmptyString(lan_dhcp_config["option_160"]) then
+        table.insert(subnet_config["option-data"], {
+          name = "option-160",
+          code = 160,
+          data = lan_dhcp_config["option_160"]
+        })
+      end
+
+      -- Add any extra options from the configuration
+      if lan_dhcp_config["options"] then
+        for _, opt in ipairs(lan_dhcp_config["options"]) do
+          -- Options here are ISC specific, no need add add them here
+          -- we will support a custom configuration file to be merged with 
+          -- the one generated here to handle custom options.
+        end
+      end
+
+      table.insert(subnet4_configs, subnet_config)
+    end
+  end
+
+  -- Build host reservations (static leases)
+  for mac, lease in pairs(dhcp_config.leases or {}) do
+    table.insert(reservations, {
+      ["hw-address"] = mac,
+      ["ip-address"] = lease.ip,
+      hostname = lease.hostname
+    })
+  end
+
+  -- Build the complete Kea DHCP4 configuration
+  local kea_config = {
+    ["Dhcp4"] = {
+      ["interfaces-config"] = {
+        interfaces = lan_interfaces,
+        ["dhcp-socket-type"] = "raw"
+      },
+      ["valid-lifetime"] = 4000,
+      ["renew-timer"] = 1000,
+      ["rebind-timer"] = 2000,
+      ["lease-database"] = {
+        type = "memfile",
+        ["persist"] = true,
+        name = "/var/lib/kea/dhcp4.leases"
+      },
+      ["expired-leases-processing"] = {
+        ["reclaim-timer-wait-time"] = 10,
+        ["flush-reclaimed-timer-wait-time"] = 25,
+        ["hold-reclaimed-time"] = 3600,
+        ["max-reclaim-leases"] = 100,
+        ["max-reclaim-time"] = 250,
+        ["unwarned-reclaim-cycles"] = 5
+      },
+      subnet4 = subnet4_configs,
+      reservations = reservations,
+      ["loggers"] = {
+        {
+          name = "kea-dhcp4",
+          ["output_options"] = {
+            {
+              output = "/var/log/kea-dhcp4.log",
+              maxsize = 10485760,
+              maxver = 8,
+              flush = true
+            }
+          },
+          severity = "INFO",
+          ["debuglevel"] = 0
+        }
+      }
+    }
+  }
+
+  -- Apply global DHCP options if present
+  if dhcp_config.options then
+    local global_options = {}
+    for _, opt in ipairs(dhcp_config.options) do
+      -- Parse and convert ISC format options to Kea JSON format
+      -- This is a simplified version and may need enhancement
+      -- depending on the specific option format used
+    end
+  end
+
+  -- Write the Kea DHCP4 configuration file in JSON format
+  local f = sys_utils.openFile("/etc/kea/kea-dhcp4.conf", "w")
+  if not f then
+    traceError(TRACE_ERROR, TRACE_CONSOLE, "Cannot open /etc/kea/kea-dhcp4.conf for writing")
+    return false
+  end
+
+  local json_str = json.encode(kea_config, { indent = true })
+  if not json_str then
+    traceError(TRACE_ERROR, TRACE_CONSOLE, "Failed to encode Kea configuration to JSON")
+    f:close()
+    return false
+  end
+
+  f:write(json_str)
+  f:close()
+
+  return true
+end
+
+-- ###############################################################
+
+return kea_dhcp_server