probe/discovery/session/discovery-session.go

package session

import (
	"encoding/json"
	"fmt"
	"log"
	"net"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"

	omd "git.loafle.net/overflow/model/discovery"
	omm "git.loafle.net/overflow/model/meta"
	omu "git.loafle.net/overflow/model/util"
	ouej "git.loafle.net/overflow/util-go/encoding/json"
	ounc "git.loafle.net/overflow/util-go/net/cidr"
	"git.loafle.net/overflow_scanner/probe/discovery/types"
	"git.loafle.net/overflow_scanner/probe/internal/pcap"
)

type DiscoverySession interface {
	InitWithRequest(request types.DiscoveryRequest) error

	DiscoveryRequest() types.DiscoveryRequest

	PCapScanner() pcap.PCapScanner

	Zone() *omd.Zone
	Host() *omd.Host
	Port() *omd.Port

	DiscoveryConfig() *omd.DiscoveryConfig

	DiscoverHost() *omd.DiscoverHost
	DiscoverPort() *omd.DiscoverPort
	DiscoverService() *omd.DiscoverService

	TargetHosts() []net.IP
	IsTargetHost(host *omd.Host) bool
	IsTargetPort(port *omd.Port) bool
	IsTargetService(service *omd.Service) bool

	HostNeedScan(host *omd.Host, discovererType *omm.MetaDiscovererType) bool

	SetDiscoveryDelegator(chan<- interface{})

	AddHost(discoveredBy *omm.MetaDiscovererType, host *omd.Host, meta map[string]string) *omd.Host
	AddPort(discoveredBy *omm.MetaDiscovererType, port *omd.Port, meta map[string]string) *omd.Port
	AddService(discoveredBy *omm.MetaDiscovererType, service *omd.Service, meta map[string]string) *omd.Service
	AddServiceUnknown(discoveredBy *omm.MetaDiscovererType, port *omd.Port) *omd.Service

	DiscoveredHost(address string) *omd.Host
	DiscoveredAllHosts(includeMac bool) map[string]*omd.Host
	DiscoveredPort(host *omd.Host, portNumber int) map[string]*omd.Port
	DiscoveredAllPorts() map[*omd.Host]map[json.Number]map[string]*omd.Port
	DiscoveredService(port *omd.Port, name string) *omd.Service
	DiscoveredServices(port *omd.Port) map[string]*omd.Service
	DiscoveredAllServices() map[*omd.Port]map[string]*omd.Service
	Privileged() bool

	Shutdown()
	StopChan() <-chan struct{}
}

type ofDiscoverySession struct {
	discoveryRequest types.DiscoveryRequest
	pCapScanner      pcap.PCapScanner

	zone *omd.Zone
	host *omd.Host
	port *omd.Port

	discoveryConfig *omd.DiscoveryConfig

	discoverHost    *omd.DiscoverHost
	discoverPort    *omd.DiscoverPort
	discoverService *omd.DiscoverService

	targetHosts         []net.IP
	targetHostAddresses map[string]bool
	targetPortNumbers   map[int]bool

	discoveryDelegator chan<- interface{}

	discoveredMtx   sync.RWMutex
	hosts           map[string]*omd.Host
	includeMacHosts map[string]*omd.Host
	ports           map[*omd.Host]map[json.Number]map[string]*omd.Port
	services        map[*omd.Port]map[string]*omd.Service
	privileged      bool

	hostScanned    map[string]map[string]bool
	hostScannedMtx sync.Mutex

	stopped  atomic.Value
	stopChan chan struct{}
}

func (ds *ofDiscoverySession) init(request types.DiscoveryRequest) {
	ds.discoveryRequest = request
	ds.zone = nil
	ds.host = nil
	ds.port = nil
	ds.discoverHost = nil
	ds.discoverPort = nil
	ds.discoverService = nil
	ds.pCapScanner = nil

	ds.targetHosts = nil
	ds.targetHostAddresses = nil
	ds.targetPortNumbers = nil
	ds.hosts = make(map[string]*omd.Host)
	ds.includeMacHosts = make(map[string]*omd.Host)
	ds.ports = make(map[*omd.Host]map[json.Number]map[string]*omd.Port)
	ds.services = make(map[*omd.Port]map[string]*omd.Service)
	ds.hostScanned = make(map[string]map[string]bool)

	ds.stopped.Store(false)
	ds.stopChan = make(chan struct{})
}

func (ds *ofDiscoverySession) InitWithRequest(request types.DiscoveryRequest) error {
	ds.init(request)

	params := request.Params()

	switch request.RequestType() {
	case types.DiscoveryRequestTypeHost:
		if nil == params || 2 != len(params) {
			return fmt.Errorf("Parameter is not valid")
		}

		zone, ok := params[0].(*omd.Zone)
		if !ok {
			return fmt.Errorf("Zone of parameter is not valid")
		}
		ds.setZone(zone)

		discoverHost, ok := params[1].(*omd.DiscoverHost)
		if !ok {
			return fmt.Errorf("DiscoverHost of parameter is not valid")
		}
		if err := ds.setDiscoverHost(discoverHost); nil != err {
			return err
		}

		if nil == discoverHost.DiscoveryConfig {
			return fmt.Errorf("DiscoveryConfig of parameter is not valid")
		}
		ds.discoveryConfig = discoverHost.DiscoveryConfig

	case types.DiscoveryRequestTypePort:
		if nil == params || 2 != len(params) {
			return fmt.Errorf("Parameter is not valid")
		}

		host, ok := params[0].(*omd.Host)
		if !ok {
			return fmt.Errorf("Host of parameter is not valid")
		}
		ds.setHost(host)

		discoverPort, ok := params[1].(*omd.DiscoverPort)
		if !ok {
			return fmt.Errorf("DiscoverPort of parameter is not valid")
		}
		if err := ds.setDiscoverPort(discoverPort); nil != err {
			return err
		}

		if nil == discoverPort.DiscoveryConfig {
			return fmt.Errorf("DiscoveryConfig of parameter is not valid")
		}
		ds.discoveryConfig = discoverPort.DiscoveryConfig

	case types.DiscoveryRequestTypeService:
		if nil == params || 2 != len(params) {
			return fmt.Errorf("Parameter is not valid")
		}

		port, ok := params[0].(*omd.Port)
		if !ok {
			return fmt.Errorf("Port of parameter is not valid")
		}
		ds.setPort(port)

		discoverService, ok := params[1].(*omd.DiscoverService)
		if !ok {
			return fmt.Errorf("DiscoverService of parameter is not valid")
		}
		if err := ds.setDiscoverService(discoverService); nil != err {
			return err
		}

		if nil == discoverService.DiscoveryConfig {
			return fmt.Errorf("DiscoveryConfig of parameter is not valid")
		}
		ds.discoveryConfig = discoverService.DiscoveryConfig
	}

	_pCapScanner := pcap.NewPCapScanner(ds.zone)
	if err := _pCapScanner.Start(); nil == err {
		ds.pCapScanner = _pCapScanner
		ds.privileged = true
		log.Print("Privileged mode")
	} else {
		log.Print(err)
		ds.privileged = false
		log.Print("Unprivileged mode")
	}

	return nil
}

func (ds *ofDiscoverySession) PCapScanner() pcap.PCapScanner {
	return ds.pCapScanner
}

func (ds *ofDiscoverySession) Privileged() bool {
	return ds.privileged
}

func (ds *ofDiscoverySession) SetDiscoveryDelegator(discoveryDelegator chan<- interface{}) {
	ds.discoveryDelegator = discoveryDelegator
}

func (ds *ofDiscoverySession) DiscoveryRequest() types.DiscoveryRequest {
	return ds.discoveryRequest
}

func (ds *ofDiscoverySession) Zone() *omd.Zone {
	return ds.zone
}
func (ds *ofDiscoverySession) Host() *omd.Host {
	return ds.host
}
func (ds *ofDiscoverySession) Port() *omd.Port {
	return ds.port
}

func (ds *ofDiscoverySession) DiscoveryConfig() *omd.DiscoveryConfig {
	return ds.discoveryConfig
}

func (ds *ofDiscoverySession) DiscoverHost() *omd.DiscoverHost {
	return ds.discoverHost
}
func (ds *ofDiscoverySession) DiscoverPort() *omd.DiscoverPort {
	return ds.discoverPort
}
func (ds *ofDiscoverySession) DiscoverService() *omd.DiscoverService {
	return ds.discoverService
}

func (ds *ofDiscoverySession) TargetHosts() []net.IP {
	return ds.targetHosts
}

func (ds *ofDiscoverySession) IsTargetHost(host *omd.Host) bool {
	if nil == ds.targetHostAddresses {
		return false
	}

	if _, ok := ds.targetHostAddresses[host.Address]; ok {
		return true
	}

	return false
}

func (ds *ofDiscoverySession) IsTargetPort(port *omd.Port) bool {
	if nil == ds.targetPortNumbers || 0 == len(ds.targetPortNumbers) {
		return false
	}

	portNumber, err := ouej.NumberToInt(port.PortNumber)
	if nil != err {
		return false
	}

	if !ds.IsTargetHost(port.Host) {
		return false
	}

	if _, ok := ds.targetPortNumbers[portNumber]; ok {
		return true
	}

	return false
}

func (ds *ofDiscoverySession) IsTargetService(service *omd.Service) bool {
	if nil == ds.discoverService {
		return false
	}

	if !ds.IsTargetPort(service.Port) {
		return false
	}

	return true
}

func (ds *ofDiscoverySession) HostNeedScan(host *omd.Host, discovererType *omm.MetaDiscovererType) bool {
	ds.hostScannedMtx.Lock()
	defer ds.hostScannedMtx.Unlock()

	sd, ok := ds.hostScanned[host.Address]
	if !ok {
		sd = make(map[string]bool)
		sd[discovererType.Key] = true
		ds.hostScanned[host.Address] = sd
		return true
	}

	_, ok = sd[discovererType.Key]
	if !ok {
		sd[discovererType.Key] = true
		return true
	}

	return false
}

func (ds *ofDiscoverySession) AddHost(discoveredBy *omm.MetaDiscovererType, host *omd.Host, meta map[string]string) *omd.Host {
	ds.discoveredMtx.Lock()
	defer ds.discoveredMtx.Unlock()

	h, modified := ds.findHost(host)

	if "" == h.Mac && "" != host.Mac {
		h.Mac = host.Mac
		modified = true
	}

	if "" == h.OsType && "" != host.OsType {
		h.OsType = host.OsType
		modified = true
	}

	if omd.DefaultHostType == h.HostType && "" != host.HostType {
		h.HostType = host.HostType
		modified = true
	}

	if omd.DefaultHostVendor == h.HostVendor && "" != host.HostVendor {
		h.HostVendor = host.HostVendor
		modified = true
	}

	if omd.DefaultHostModel == h.HostModel && "" != host.HostModel {
		h.HostModel = host.HostModel
		modified = true
	}

	discoveredBys, discoveredByModified := ds.appendDiscoveredBy(discoveredBy, h.DiscoveredBy)
	if discoveredByModified {
		h.DiscoveredBy = discoveredBys
		modified = true
	}

	metas, metaModified := ds.appendMeta(discoveredBy, h.Meta, meta)
	if metaModified {
		h.Meta = metas
		modified = true
	}

	h, addtionalModified := ds.addtionalHost(discoveredBy, h)
	if addtionalModified {
		modified = true
	}

	if modified {
		ds.delegate(h)
	}

	return h
}

func (ds *ofDiscoverySession) AddPort(discoveredBy *omm.MetaDiscovererType, port *omd.Port, meta map[string]string) *omd.Port {
	ds.discoveredMtx.Lock()
	defer ds.discoveredMtx.Unlock()

	p, modified := ds.findPort(port)

	discoveredBys, discoveredByModified := ds.appendDiscoveredBy(discoveredBy, p.DiscoveredBy)
	if discoveredByModified {
		p.DiscoveredBy = discoveredBys
		modified = true
	}

	metas, metaModified := ds.appendMeta(discoveredBy, p.Meta, meta)
	if metaModified {
		p.Meta = metas
		modified = metaModified
	}

	if modified {
		ds.delegate(p)
	}

	return p
}

func (ds *ofDiscoverySession) AddService(discoveredBy *omm.MetaDiscovererType, service *omd.Service, meta map[string]string) *omd.Service {
	ds.discoveredMtx.Lock()
	defer ds.discoveredMtx.Unlock()

	s, modified := ds.findService(service)

	if omd.DefaultServiceType == s.ServiceType && "" != service.ServiceType {
		s.ServiceType = service.ServiceType
		modified = true
	}

	if omd.DefaultServiceVendor == s.ServiceVendor && "" != service.ServiceVendor {
		s.ServiceVendor = service.ServiceVendor
		modified = true
	}

	if omd.DefaultServiceVersion == s.ServiceVersion && "" != service.ServiceVersion {
		s.ServiceVersion = service.ServiceVersion
		modified = true
	}

	discoveredBys, discoveredByModified := ds.appendDiscoveredBy(discoveredBy, s.DiscoveredBy)
	if discoveredByModified {
		s.DiscoveredBy = discoveredBys
		modified = true
	}

	metas, metaModified := ds.appendMeta(discoveredBy, s.Meta, meta)
	if metaModified {
		s.Meta = metas
		modified = metaModified
	}

	s, addtionalModified := ds.addtionalService(discoveredBy, s)
	if addtionalModified {
		modified = true
	}

	if modified {
		ds.delegate(s)
	}

	return s
}

func (ds *ofDiscoverySession) AddServiceUnknown(discoveredBy *omm.MetaDiscovererType, port *omd.Port) *omd.Service {
	if nil == ds.DiscoveredServices(port) {
		s := omd.NewService(
			port,
			omm.ToMetaCryptoType(omm.MetaCryptoTypeEnumNONE),
			omd.UnknownServiceKey,
		)
		s.Name = ""
		s.ServiceType = omm.MetaServiceTypeEnumUNKNOWN.String()
		s.ServiceVendor = ""
		s.ServiceVersion = ""
		s.DiscoveredDate = omu.NowPtr()
		return ds.AddService(discoveredBy, s, nil)
	}

	return nil
}

func (ds *ofDiscoverySession) DiscoveredHost(address string) *omd.Host {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	h, ok := ds.hosts[address]
	if !ok {
		return nil
	}

	return h
}

func (ds *ofDiscoverySession) DiscoveredAllHosts(includeMac bool) map[string]*omd.Host {
	if includeMac {
		return ds.includeMacHosts
	}
	return ds.hosts
}

func (ds *ofDiscoverySession) DiscoveredPort(host *omd.Host, portNumber int) map[string]*omd.Port {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	h, _ := ds.findHost(host)
	if nil == h {
		return nil
	}

	hostPorts, ok := ds.ports[h]
	if !ok {
		return nil
	}

	ports, ok := hostPorts[json.Number(strconv.Itoa(portNumber))]
	if !ok {
		return nil
	}

	return ports
}

func (ds *ofDiscoverySession) DiscoveredAllPorts() map[*omd.Host]map[json.Number]map[string]*omd.Port {
	return ds.ports
}

func (ds *ofDiscoverySession) DiscoveredService(port *omd.Port, name string) *omd.Service {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	p, _ := ds.findPort(port)
	if nil == p {
		return nil
	}

	services, ok := ds.services[p]
	if !ok {
		return nil
	}

	s, ok := services[name]
	if !ok {
		return nil
	}

	return s
}

func (ds *ofDiscoverySession) DiscoveredServices(port *omd.Port) map[string]*omd.Service {
	ds.discoveredMtx.RLock()
	defer ds.discoveredMtx.RUnlock()

	p, _ := ds.findPort(port)
	if nil == p {
		return nil
	}

	services, ok := ds.services[p]
	if !ok {
		return nil
	}

	return services
}

func (ds *ofDiscoverySession) DiscoveredAllServices() map[*omd.Port]map[string]*omd.Service {
	return ds.services
}

func (ds *ofDiscoverySession) StopChan() <-chan struct{} {
	return ds.stopChan
}

func (ds *ofDiscoverySession) delegate(data interface{}) {
	if true == ds.stopped.Load().(bool) {
		return
	}

	switch v := data.(type) {
	case *omd.Host:
		if !ds.IsTargetHost(v) {
			return
		}
	case *omd.Port:
		if !ds.IsTargetPort(v) {
			return
		}
	case *omd.Service:
		if !ds.IsTargetService(v) {
			return
		}
	default:
		return
	}

	if nil != ds.discoveryDelegator {
		ds.discoveryDelegator <- data
	}
}

func (ds *ofDiscoverySession) Shutdown() {
	if ds.stopped.Load().(bool) {
		return
	}

	ds.stopped.Store(true)
	close(ds.stopChan)
}

func (ds *ofDiscoverySession) findHost(host *omd.Host) (h *omd.Host, modified bool) {
	modified = false
	var ok bool

	if "" == host.HostType {
		host.HostType = omd.DefaultHostType
	}
	if "" == host.OsType {
		host.OsType = omd.DefaultOsType
	}

	h, ok = ds.hosts[host.Address]
	if !ok {
		ds.hosts[host.Address] = host
		if "" != host.Mac {
			ds.includeMacHosts[host.Address] = host
		}
		h = host
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) findPort(port *omd.Port) (p *omd.Port, modified bool) {
	modified = false
	var ok bool

	h, _ := ds.findHost(port.Host)
	if nil == h {
		return
	}

	hostPorts, ok := ds.ports[h]
	if !ok {
		ds.ports[h] = make(map[json.Number]map[string]*omd.Port)
		hostPorts = ds.ports[h]
	}

	ports, ok := hostPorts[port.PortNumber]
	if !ok {
		hostPorts[port.PortNumber] = make(map[string]*omd.Port)
		ports = hostPorts[port.PortNumber]
	}

	p, ok = ports[port.MetaPortType.Key]
	if !ok {
		ports[port.MetaPortType.Key] = port
		p = ports[port.MetaPortType.Key]
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) findService(service *omd.Service) (s *omd.Service, modified bool) {
	modified = false
	var ok bool

	p, _ := ds.findPort(service.Port)
	if nil == p {
		return
	}

	services, ok := ds.services[p]
	if !ok {
		ds.services[p] = make(map[string]*omd.Service)
		services = ds.services[p]
	} else {
		if _, ok := services[omd.UnknownServiceKey]; ok {
			delete(services, omd.UnknownServiceKey)
		}
	}

	s, ok = services[service.Key]
	if !ok {
		services[service.Key] = service
		s = services[service.Key]
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) addtionalHost(discoveredBy *omm.MetaDiscovererType, host *omd.Host) (h *omd.Host, modified bool) {
	h = host
	modified = false

	if nil == host.Meta {
		return
	}

	meta, ok := host.Meta[discoveredBy.Key]
	if !ok || nil == meta || 0 == len(meta) {
		return
	}

	switch omm.ToMetaDiscovererTypeEnum(discoveredBy) {
	case omm.MetaDiscovererTypeEnumMDNS:
		_h, _modified := ds.addtionalHostMDNS(h, meta)
		if _modified {
			h = _h
			modified = true
		}
	case omm.MetaDiscovererTypeEnumUPnP:
		_h, _modified := ds.addtionalHostUPnP(h, meta)
		if _modified {
			h = _h
			modified = true
		}
	}

	return
}

func (ds *ofDiscoverySession) addtionalHostMDNS(host *omd.Host, meta map[string]string) (h *omd.Host, modified bool) {
	h = host
	modified = false

	_vendor, ok := meta["vendor"]
	if ok || "" != _vendor {
		h.HostVendor = _vendor
		modified = true
	}

	_model, ok := meta["model"]
	if ok || "" != _model {
		h.HostModel = _model
		if "Synology" == _vendor && strings.Contains(_model, "DS1817+") {
			h.HostType = omm.MetaHostTypeEnumNAS.String()
		}
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) addtionalHostUPnP(host *omd.Host, meta map[string]string) (h *omd.Host, modified bool) {
	h = host
	modified = false

	_vendor, ok := meta["Manufacturer"]
	if ok || "" != _vendor {
		h.HostVendor = _vendor
		modified = true
	}

	_model, ok := meta["ModelName"]
	if ok || "" != _model {
		h.HostModel = _model
		if "EFM Networks" == _vendor && strings.Contains(_model, "ipTIME A2004NS") {
			h.HostType = omm.MetaHostTypeEnumRouter.String()
		}
		modified = true
	}

	return
}

func (ds *ofDiscoverySession) addtionalService(discoveredBy *omm.MetaDiscovererType, service *omd.Service) (s *omd.Service, modified bool) {
	s = service
	modified = false

	if nil == service.Meta {
		return
	}

	meta, ok := service.Meta[discoveredBy.Key]
	if !ok || nil == meta || 0 == len(meta) {
		return
	}

	switch omm.ToMetaDiscovererTypeEnum(discoveredBy) {
	case omm.MetaDiscovererTypeEnumMDNS:
		_s, _modified := ds.addtionalServiceMDNS(s, meta)
		if _modified {
			s = _s
			modified = true
		}
	}

	return
}

func (ds *ofDiscoverySession) addtionalServiceMDNS(service *omd.Service, meta map[string]string) (s *omd.Service, modified bool) {
	s = service
	modified = false

	portNumber, err := ouej.NumberToInt(service.Port.PortNumber)
	if nil != err {
		log.Print(err)
		return
	}

	switch portNumber {
	case 515:
		if "printer" == service.Name || "printer" == service.Key {
			_h, _ := ds.findHost(service.Port.Host)
			_h.HostType = omm.MetaHostTypeEnumPrinter.String()
			_h.Name = service.Name
			ds.delegate(_h)
		}
	case 9100:
		if "pdl-datastream" == service.Name || "pdl-datastream" == service.Key {
			_h, _ := ds.findHost(service.Port.Host)
			_h.HostType = omm.MetaHostTypeEnumPrinter.String()
			_h.Name = service.Name
			ds.delegate(_h)
		}
	}

	return
}

func (ds *ofDiscoverySession) appendDiscoveredBy(discoveredBy *omm.MetaDiscovererType, oriDiscoveredBy []*omm.MetaDiscovererType) (resultDiscoveredBy []*omm.MetaDiscovererType, modified bool) {
	modified = false

	if nil == discoveredBy {
		resultDiscoveredBy = oriDiscoveredBy
		return
	}

	if nil == oriDiscoveredBy {
		resultDiscoveredBy = []*omm.MetaDiscovererType{
			discoveredBy,
		}
		modified = true
		return
	}

	for _, v := range oriDiscoveredBy {
		if v.Key == discoveredBy.Key {
			resultDiscoveredBy = oriDiscoveredBy
			return
		}
	}

	oriDiscoveredBy = append(oriDiscoveredBy, discoveredBy)
	resultDiscoveredBy = oriDiscoveredBy
	modified = true

	return
}

func (ds *ofDiscoverySession) appendMeta(discoveredBy *omm.MetaDiscovererType, oriMetas map[string]map[string]string, newMeta map[string]string) (resultMetas map[string]map[string]string, modified bool) {
	modified = false
	if nil == newMeta || 0 == len(newMeta) {
		resultMetas = oriMetas
		return
	}

	if nil == oriMetas {
		resultMetas = map[string]map[string]string{
			discoveredBy.Key: newMeta,
		}
		modified = true
		return
	}

	oriMeta, ok := oriMetas[discoveredBy.Key]
	if !ok {
		oriMetas[discoveredBy.Key] = newMeta
		resultMetas = oriMetas
		return
	}

LOOP:
	for k, v := range newMeta {
		_v, _ok := oriMeta[k]
		if !_ok {
			oriMeta[k] = v
			modified = true
			continue LOOP
		}
		if v == _v {
			continue LOOP
		}
		oriMeta[k] = fmt.Sprintf("%s|||%s", _v, v)
		modified = true
	}

	resultMetas = oriMetas

	return
}

func (ds *ofDiscoverySession) setZone(zone *omd.Zone) {
	if nil == zone {
		return
	}
	ds.zone = zone
}

func (ds *ofDiscoverySession) setHost(host *omd.Host) {
	if nil == host {
		return
	}
	ds.setZone(host.Zone)
	ds.host = host
}

func (ds *ofDiscoverySession) setPort(port *omd.Port) {
	if nil == port {
		return
	}
	ds.setHost(port.Host)
	ds.port = port
}

func (ds *ofDiscoverySession) setDiscoverHost(discoverHost *omd.DiscoverHost) error {
	if nil == discoverHost {
		return nil
	}

	if err := ds.setTargetHosts(ds.zone, discoverHost); nil != err {
		return err
	}

	ds.discoverHost = discoverHost

	return ds.setDiscoverPort(discoverHost.DiscoverPort)
}

func (ds *ofDiscoverySession) setDiscoverPort(discoverPort *omd.DiscoverPort) error {
	if nil == discoverPort {
		return nil
	}

	if err := ds.setTargetPortNumbers(discoverPort); nil != err {
		return err
	}

	ds.discoverPort = discoverPort
	return ds.setDiscoverService(discoverPort.DiscoverService)
}

func (ds *ofDiscoverySession) setDiscoverService(discoverService *omd.DiscoverService) error {
	if nil == discoverService {
		return nil
	}

	ds.discoverService = discoverService

	return nil
}

func (ds *ofDiscoverySession) setTargetHosts(zone *omd.Zone, discoverHost *omd.DiscoverHost) error {
	cr, err := ounc.NewCIDRRanger(zone.Network)
	if nil != err {
		return err
	}

	var firstIP net.IP
	if "" != discoverHost.FirstScanRange {
		firstIP = net.ParseIP(discoverHost.FirstScanRange)
		if nil == firstIP {
			return fmt.Errorf("IP(%v) of FirstScanRange host is not valid", firstIP)
		}
	}
	var lastIP net.IP
	if "" != discoverHost.LastScanRange {
		lastIP = net.ParseIP(discoverHost.LastScanRange)
		if nil == lastIP {
			return fmt.Errorf("IP(%v) of LastScanRange host is not valid", lastIP)
		}
	}

	includeIPs := make([]net.IP, 0)
	for _, iHost := range discoverHost.IncludeHosts {
		iIP := net.ParseIP(iHost)
		if nil == iIP {
			return fmt.Errorf("IP(%v) of include host is not valid", iHost)
		}
		includeIPs = append(includeIPs, iIP)
	}

	excludeIPs := make([]net.IP, 0)
	for _, eHost := range discoverHost.ExcludeHosts {
		eIP := net.ParseIP(eHost)
		if nil == eIP {
			return fmt.Errorf("IP(%v) of exclude host is not valid", eHost)
		}
		excludeIPs = append(excludeIPs, eIP)
	}

	ranges, err := cr.Ranges(firstIP, lastIP, includeIPs, excludeIPs)
	if nil != err {
		return err
	}

	ds.targetHosts = ranges
	ds.targetHostAddresses = make(map[string]bool, len(ranges))

	for _, ip := range ranges {
		ds.targetHostAddresses[ip.String()] = true
	}

	return nil
}

func (ds *ofDiscoverySession) setTargetPortNumbers(discoverPort *omd.DiscoverPort) error {
	if nil == discoverPort {
		return nil
	}

	ds.targetPortNumbers = make(map[int]bool, 0)

LOOP:
	for portNumber := discoverPort.FirstScanRange; portNumber < discoverPort.LastScanRange; portNumber++ {
		if nil != discoverPort.ExcludePorts {
			for _, exPortNumber := range discoverPort.ExcludePorts {
				if portNumber == exPortNumber {
					continue LOOP
				}
			}
		}
		ds.targetPortNumbers[portNumber] = true
	}

	return nil
}

var discoverySessionPool sync.Pool

func RetainDiscoverySession() *ofDiscoverySession {
	v := discoverySessionPool.Get()
	var ds *ofDiscoverySession
	if v == nil {
		ds = &ofDiscoverySession{}
	} else {
		ds = v.(*ofDiscoverySession)
	}

	return ds
}

func ReleaseDiscoverySession(ds *ofDiscoverySession) {
	ds.stopChan = nil

	if nil != ds.pCapScanner {
		ds.pCapScanner.Stop()
	}

	ds.pCapScanner = nil
	ds.discoveryRequest = nil
	ds.zone = nil
	ds.host = nil
	ds.port = nil

	ds.discoveryConfig = nil

	ds.discoverHost = nil
	ds.discoverPort = nil
	ds.discoverService = nil

	ds.targetHosts = nil
	ds.targetHostAddresses = nil
	ds.targetPortNumbers = nil

	ds.discoveryDelegator = nil

	ds.includeMacHosts = nil
	ds.hosts = nil
	ds.ports = nil
	ds.services = nil
	ds.hostScanned = nil

	discoverySessionPool.Put(ds)
}