Controls the DHCP service enabling status. More...

#include <network_state.h>

Inheritance diagram for isc::dhcp::NetworkState:

Public Types
typedef std::set< std::string >	Networks
	Type of the container holding collection of shared network names.

typedef std::set< SubnetID >	Subnets
	Type of the container holding collection of subnet identifiers.

Public Member Functions
	NetworkState ()
	Constructor.

void	delayedEnableService (const unsigned int seconds, unsigned int origin)
	Schedules enabling DHCP service in the future.

void	disableService (unsigned int origin)
	Disable the DHCP service state for respective transition origin.

void	enableService (unsigned int origin)
	Enable the DHCP service state for respective transition origin.

bool	isDelayedEnableService () const
	Checks if delayed enabling of DHCP services is scheduled.

bool	isServiceEnabled () const
	Checks if the DHCP service is globally enabled.

void	resetForDbConnection ()
	Reset internal counters for database connection.

void	resetForLocalCommands ()
	Reset origins for local commands.

void	resetForRemoteCommands ()
	Reset origins for remote commands.

Public Member Functions inherited from isc::data::CfgToElement
virtual	~CfgToElement ()
	Destructor.

Static Public Attributes
static const unsigned int	DB_CONNECTION = 3000
	The network state is being altered by the DB connection recovery mechanics.

static const unsigned int	HA_LOCAL_COMMAND = 1000
	The network state is being altered by an HA internal command.

static const unsigned int	HA_REMOTE_COMMAND = 2000
	The network state is being altered by a "dhcp-disable" or "dhcp-enable" command sent by a HA partner.

static const unsigned int	USER_COMMAND = 1
	Origin of the network state transition.

Selective disabling/enabling DHCP service per scopes
void	selectiveDisable (const NetworkState::Subnets &subnets)
	Disable DHCP service for selected subnets.

void	selectiveDisable (const NetworkState::Networks &networks)
	Disable DHCP service for selected networks.

void	selectiveEnable (const NetworkState::Subnets &subnets)
	Enable DHCP service for selected subnets.

void	selectiveEnable (const NetworkState::Networks &networks)
	Enable DHCP service for selected networks.

virtual isc::data::ElementPtr	toElement () const
	The network state as Element.

Detailed Description

Controls the DHCP service enabling status.

Sometimes, a DHCP server must pause responding to the DHCP queries. Typical cases include a database connection loss when the server tries to reconnect and various cases related to the High Availability operation. It is also possible to explicitly turn the DHCP service on and off via the control channel. This class receives calls from different origins to disable and re-enable the DHCP service.

The general rule is that the DHCP service must be disabled when the class receives at least one request to disable the service from any origin. The service must be re-enabled when all requestors previously disabling the service re-enabled it. This class also allows for specifying a timeout value for each request, after which the service gets re-enabled automatically. It is particularly useful in HA when there is no guarantee that the HA partner will be able to re-enable the service because it may experience an unexpected outage. In that case, the "max-period" parameter must accompany the "dhcp-disable" command to ensure that the service will eventually be re-enabled. The HA hook library may include several independent relationships. Each relationship is treated as a separate origin by this class. If one relationship disables the DHCP service, the service must remain disabled even when any other relationship requests enabling it. The service is re-enabled after all relationships requested re-enabling it (e.g., they all finished synchronizing the lease database).

The HA service instances must have unique identifiers they use to specify the origin. For example, an HAService with the identifier of 1 should request disabling the local service like this:

NetworkState state;

state.disableService(NetworkState::HA_LOCAL_COMMAND + 1);

isc::dhcp::NetworkState

Controls the DHCP service enabling status.

Definition network_state.h:72

isc::dhcp::NetworkState::HA_LOCAL_COMMAND

static const unsigned int HA_LOCAL_COMMAND

The network state is being altered by an HA internal command.

Definition network_state.h:91

isc::dhcp::NetworkState::disableService

void disableService(unsigned int origin)

Disable the DHCP service state for respective transition origin.

Definition network_state.cc:236

The DHCP state can also be altered by the database recovery mechanism, which disables the service on connection loss and re-enables it after the connection is restored. Unlike in HA, this is implemented using an internal counter. In this case, there is one origin for all database connections. The requests for the NetworkState::DB_CONNECTION are counted, and the DHCP service is re-enabled when the counter reaches 0.

Todo: We should consider migrating the database recovery to the same mechanism we use for the HA. The reference counting works because the database connection classes ensure that for each request to disable the DHCP service, there is a corresponding request to enable the service. It prevents the situation that the service remains disabled because there were more requests to disable than to enable the service. It is hard to ensure the same consistency for the HA.

Definition at line 72 of file network_state.h.

Member Typedef Documentation

◆ Networks

std::set<std::string> isc::dhcp::NetworkState::Networks

Type of the container holding collection of shared network names.

Definition at line 108 of file network_state.h.

◆ Subnets

std::set<SubnetID> isc::dhcp::NetworkState::Subnets

Type of the container holding collection of subnet identifiers.

Definition at line 105 of file network_state.h.

Constructor & Destructor Documentation

◆ NetworkState()

isc::dhcp::NetworkState::NetworkState ( )

Constructor.

Definition at line 231 of file network_state.cc.

Member Function Documentation

◆ delayedEnableService()

void isc::dhcp::NetworkState::delayedEnableService	(	const unsigned int	seconds,
		unsigned int	origin )

Schedules enabling DHCP service in the future.

Parameters

seconds	Number of seconds after which the service should be enabled unless `enableAll` is enabled before that time.
origin	The origin of the state transition.

Definition at line 266 of file network_state.cc.

◆ disableService()

void isc::dhcp::NetworkState::disableService ( unsigned int origin )

Disable the DHCP service state for respective transition origin.

Note: If any of the user commands, HA internal commands or connection recovery processes disable the dhcp service, the service will remain disabled until all flags are cleared.

Parameters

origin The origin of the state transition.

Definition at line 236 of file network_state.cc.

◆ enableService()

void isc::dhcp::NetworkState::enableService ( unsigned int origin )

Enable the DHCP service state for respective transition origin.

Note: If any of the user commands, HA internal commands or connection recovery processes disable the dhcp service, the service will remain disabled until all flags are cleared.

Parameters

origin The origin of the state transition.

Definition at line 242 of file network_state.cc.

◆ isDelayedEnableService()

bool isc::dhcp::NetworkState::isDelayedEnableService ( ) const

Checks if delayed enabling of DHCP services is scheduled.

It indicates that the timer is present which counts the time until delayedEnable function will be called automatically.

Returns: true if delayed enabling of the DHCP service is scheduled, false otherwise.

Definition at line 278 of file network_state.cc.

References isc::dhcp::TimerMgr::instance().

Here is the call graph for this function:

◆ isServiceEnabled()

bool isc::dhcp::NetworkState::isServiceEnabled ( ) const

Checks if the DHCP service is globally enabled.

Returns: true if the service is globally enabled, false otherwise.

Definition at line 272 of file network_state.cc.

◆ resetForDbConnection()

void isc::dhcp::NetworkState::resetForDbConnection ( )

Reset internal counters for database connection.

It results in enabling the network service if network service for all other origins is enabled.

Definition at line 248 of file network_state.cc.

◆ resetForLocalCommands()

void isc::dhcp::NetworkState::resetForLocalCommands ( )

ElementPtr isc::dhcp::NetworkState::toElement ( ) const

virtual

The network state as Element.

Returns: The network state as Element.

The network state is being altered by a user command.

Specify unique origins for different commands by adding a number to this constant.

Definition at line 85 of file network_state.h.

Referenced by isc::dhcp::NetworkStateImpl::toElement().

The documentation for this class was generated from the following files:

Public Types

Public Member Functions

Static Public Attributes

Selective disabling/enabling DHCP service per scopes

Detailed Description

Member Typedef Documentation

◆ Networks

◆ Subnets

Constructor & Destructor Documentation

◆ NetworkState()

Member Function Documentation

◆ delayedEnableService()

◆ disableService()

◆ enableService()

◆ isDelayedEnableService()

◆ isServiceEnabled()

◆ resetForDbConnection()

◆ resetForLocalCommands()

◆ resetForRemoteCommands()

◆ selectiveDisable() [1/2]

◆ selectiveDisable() [2/2]

◆ selectiveEnable() [1/2]

◆ selectiveEnable() [2/2]

◆ toElement()

Member Data Documentation

◆ DB_CONNECTION

◆ HA_LOCAL_COMMAND

◆ HA_REMOTE_COMMAND

◆ USER_COMMAND