Adding upstream version 2.4.1.upstream/2.4.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 209 insertions, 0 deletions

diff --git a/src/lib/dhcpsrv/network_state.h b/src/lib/dhcpsrv/network_state.h
new file mode 100644
index 0000000..def52e6
--- /dev/null
+++ b/src/lib/dhcpsrv/network_state.h
@@ -0,0 +1,209 @@
+// Copyright (C) 2017-2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef NETWORK_STATE_H
+#define NETWORK_STATE_H
+
+#include <cc/data.h>
+#include <dhcpsrv/subnet_id.h>
+#include <boost/scoped_ptr.hpp>
+#include <boost/shared_ptr.hpp>
+#include <set>
+#include <mutex>
+#include <string>
+
+namespace isc {
+namespace dhcp {
+
+class NetworkStateImpl;
+
+/// @brief Holds information about DHCP service enabling status.
+///
+/// When the DHCP server receives a command to disable DHCP service entirely
+/// or for specific networks, this has to be recorded to allow for re-enabling
+/// DHCP service for these networks as a result of receiving a command from
+/// the administrator or when the timeout for re-enabling the service occurs.
+/// Currently there are two types of command originating either from user or
+/// HA internal mechanism.
+/// The global state can also be altered by the DB recovery mechanism which
+/// disables the service on connection loss and re-enables it after the
+/// connection is restored. Because the server supports recovery for multiple
+/// connections, this is implemented using an internal counter.
+/// Combining all the origins of the alteration of the network state, the
+/// behavior is:
+/// a) the network state is disabled if any of the originators explicitly set
+///    the disabled flag.
+/// b) the network state is restored only if all originators explicitly clear
+///    the disabled flag.
+/// In the future, it will be possible to specify "disabled" parameter for
+/// a subnet (or network) in the configuration file to indicate that this subnet
+/// should be excluded from the service. When a command is subsequently sent to
+/// temporarily disable a service for some other subnets for a specified amount
+/// of time, only these subnets should be re-enabled when the time elapses. This
+/// class fulfills this requirement by recording the subnets disabled with a command
+/// and re-enabling them when required. The subnets specified as "disabled" in
+/// the configuration file should remain disabled until explicitly enabled with a
+/// control command.
+///
+/// This class also allows for disabling the DHCP service globally. In this case
+/// the server drops all received packets.
+///
+/// The "dhcp-disable" and "dhcp-enable" commands are used for globally disabling
+/// and enabling the DHCP service. The "dhcp-disable-scopes" and "dhcp-enable-scopes"
+/// commands are used to disable and enable DHCP service for subnets and networks.
+/// In case of the "dhcp-disable" and "dhcp-disable-scopes" commands, it is possible
+/// to specify "max-period" parameter which provides a timeout, after which the
+/// settings are reverted (service is re-enabled globally and/or for specific
+/// scopes).
+///
+/// Disabling DHCP service with a timeout is useful to guard against issues when
+/// the controlling client dies after disabling the DHCP service on the server,
+/// e.g. failover peers may instruct each other to disable the DHCP service while
+/// database synchronization takes place. If the peer subsequently dies, the
+/// surviving server must re-enable DHCP on its own.
+///
+/// @todo This class currently supports only the case of globally disabling
+/// the DHCP service. Disabling per network/subnet will be added later.
+class NetworkState {
+public:
+
+    /// @brief DHCP server type.
+    enum ServerType {
+        DHCPv4,
+        DHCPv6
+    };
+
+    /// @brief Origin of the network state transition.
+    ///
+    /// The enumeration indicates the originator of the state transition of the
+    /// network state: either user command, HA internal command or DB connection
+    /// recovery mechanism.
+    enum class Origin {
+        /// @brief The network state is being altered by a user command.
+        USER_COMMAND,
+        /// @brief The network state is being altered by a HA internal command.
+        HA_COMMAND,
+        /// @brief The network state is being altered by the DB connection
+        /// recovery mechanics.
+        DB_CONNECTION
+    };
+
+    /// @brief Type of the container holding collection of subnet identifiers.
+    typedef std::set<SubnetID> Subnets;
+
+    /// @brief Type of the container holding collection of shared network names.
+    typedef std::set<std::string> Networks;
+
+    /// @brief Constructor.
+    NetworkState(const ServerType& server_type);
+
+    /// @brief 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.
+    ///
+    /// @param origin The origin of the state transition.
+    void disableService(const NetworkState::Origin& origin);
+
+    /// @brief 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.
+    ///
+    /// @param origin The origin of the state transition.
+    void enableService(const NetworkState::Origin& origin);
+
+    /// @brief Reset internal counters.
+    ///
+    /// Reset internal counters for a specific 'origin' after the server has
+    /// been reconfigured or all the connections have been restored.
+    ///
+    /// @param type The origin for which the state flags need to be reset.
+    void reset(const NetworkState::Origin& type);
+
+    /// @brief Enables DHCP service globally and for scopes which have been
+    /// disabled as a result of control command.
+    ///
+    /// @param origin The origin of the state transition.
+    void enableAll(const NetworkState::Origin& origin);
+
+    /// @brief Schedules enabling DHCP service in the future.
+    ///
+    /// @param seconds Number of seconds after which the service should be enabled
+    /// unless @c enableAll is enabled before that time.
+    /// @param origin The origin of the state transition.
+    void delayedEnableAll(const unsigned int seconds,
+                          const NetworkState::Origin& origin);
+
+    /// @brief Checks if the DHCP service is globally enabled.
+    ///
+    /// @return true if the service is globally enabled, false otherwise.
+    bool isServiceEnabled() const;
+
+    /// @brief Checks if delayed enabling of DHCP services is scheduled.
+    ///
+    /// It indicates that the timer is present which counts the time until
+    /// @c enableAll function will be called automatically.
+    ///
+    /// @return true if delayed enabling of the DHCP service is scheduled,
+    /// false otherwise.
+    bool isDelayedEnableAll() const;
+
+    /// @name Selective disabling/enabling DHCP service per scopes
+    //@{
+
+    /// @brief Disable DHCP service for selected subnets.
+    ///
+    /// @param subnets Collection of subnet identifiers for which the service
+    /// should be disabled.
+    ///
+    /// @throw isc::NotImplemented
+    void selectiveDisable(const NetworkState::Subnets& subnets);
+
+    /// @brief Disable DHCP service for selected networks.
+    ///
+    /// @param networks Collection of shared network names for which the service
+    /// should be disabled.
+    ///
+    /// @throw isc::NotImplemented
+    void selectiveDisable(const NetworkState::Networks& networks);
+
+    /// @brief Enable DHCP service for selected subnets.
+    ///
+    /// @param subnets Collection of subnet identifiers for which the service
+    /// should be disabled.
+    ///
+    /// @throw isc::NotImplemented
+    void selectiveEnable(const NetworkState::Subnets& subnets);
+
+    /// @brief Enable DHCP service for selected networks.
+    ///
+    /// @param networks Collection of shared network names for which the service
+    /// should be enabled.
+    ///
+    /// @throw isc::NotImplemented
+    void selectiveEnable(const NetworkState::Networks& networks);
+
+    //@}
+
+private:
+
+    /// @brief Pointer to the @c NetworkState implementation.
+    boost::shared_ptr<NetworkStateImpl> impl_;
+
+    /// @brief The mutex used to protect internal state.
+    const boost::scoped_ptr<std::mutex> mutex_;
+};
+
+/// @brief Pointer to the @c NetworkState object.
+typedef boost::shared_ptr<NetworkState> NetworkStatePtr;
+
+} // end of namespace isc::dhcp
+} // end of namespace isc
+
+#endif // NETWORK_STATE_H