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Diffstat (limited to 'src/lib/config/base_command_mgr.h')
| -rw-r--r-- | src/lib/config/base_command_mgr.h | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/src/lib/config/base_command_mgr.h b/src/lib/config/base_command_mgr.h new file mode 100644 index 0000000..9cc5a7f --- /dev/null +++ b/src/lib/config/base_command_mgr.h @@ -0,0 +1,209 @@ +// Copyright (C) 2017-2020 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 BASE_COMMAND_MGR_H +#define BASE_COMMAND_MGR_H + +#include <cc/data.h> +#include <exceptions/exceptions.h> +#include <functional> +#include <map> +#include <string> + +namespace isc { +namespace config { + +/// @brief Exception indicating that the handler specified is not valid +class InvalidCommandHandler : public Exception { +public: + InvalidCommandHandler(const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Exception indicating that the command name is not valid +class InvalidCommandName : public Exception { +public: + InvalidCommandName(const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Commands Manager, responsible for processing external commands. +/// +/// Commands Manager is a generic interface for handling external commands. +/// Commands are received over control sockets. Derivations of this class +/// provide implementations of the control socket layers, e.g. unix domain +/// sockets, TCP sockets etc. This base class merely provides methods to manage +/// command handling functions, i.e. register commands, deregister commands. +/// It also includes a @ref BaseCommandMgr::processCommand method which +/// uses the command as an input and invokes appropriate handlers. +/// +/// The commands and responses are formatted using JSON. +/// See https://gitlab.isc.org/isc-projects/kea/wikis/designs/Stats-design +/// for details. +/// +/// Below is an example of the command using JSON format: +/// @code +/// { +/// "command": "statistic-get", +/// "arguments": { +/// "name": "received-packets" +/// } +/// } +/// @endcode +/// +/// And the response is: +/// +/// @code +/// { +/// "result": 0, +/// "arguments": { +/// "received-packets": [ [ 1234, "2015-04-15 12:34:45.123" ] ] +/// } +/// } +/// @endcode +/// +/// BaseCommandsMgr does not implement the commands (except one, +/// "list-commands") itself, but rather provides an interface +/// (see @ref registerCommand, @ref deregisterCommand, @ref processCommand) +/// for other components to use it. +class BaseCommandMgr { +public: + + /// @brief Defines command handler type + /// + /// Command handlers are expected to use this format. + /// + /// @param name name of the commands + /// @param params parameters specific to the command + /// @return response (created with createAnswer()) + typedef std::function<isc::data::ConstElementPtr (const std::string& name, + const isc::data::ConstElementPtr& params)> CommandHandler; + + /// @brief Defines extended command handler type. + /// + /// This command handler includes third parameter which holds the + /// entire command control message. The handler can retrieve + /// additional information from this parameter, e.g. 'service'. + /// + /// @param name name of the commands + /// @param params parameters specific to the command + /// @param original original control command. + /// @return response (created with createAnswer()) + typedef std::function<isc::data::ConstElementPtr (const std::string& name, + const isc::data::ConstElementPtr& params, + const isc::data::ConstElementPtr& original)> ExtendedCommandHandler; + + /// @brief Constructor. + /// + /// Registers hookpoint "command-processed" + /// Registers "list-commands" command. + BaseCommandMgr(); + + /// @brief Destructor. + virtual ~BaseCommandMgr() { }; + + /// @brief Triggers command processing. + /// + /// This method processes specified command. The command is specified using + /// a single Element. See @ref BaseCommandMgr for description of its syntax. + /// After the command has been handled, callouts for the hook point, + /// "command-processed" will be invoked. + /// + /// This method is virtual so it can be overridden in derived classes to + /// pre-process command and post-process response if necessary. + /// + /// This method is an entry point for dealing with a command. Internally + /// it calls @c BaseCommandMgr::handleCommand. + /// + /// @param cmd Pointer to the data element representing command in JSON + /// format. + virtual isc::data::ConstElementPtr + processCommand(const isc::data::ConstElementPtr& cmd); + + /// @brief Registers specified command handler for a given command + /// + /// @param cmd Name of the command to be handled. + /// @param handler Pointer to the method that will handle the command. + void registerCommand(const std::string& cmd, CommandHandler handler); + + /// @brief Registers specified command handler for a given command. + /// + /// This variant of the method uses extended command handler which, besides + /// command name and arguments, also has a third parameter 'original_cmd' + /// in its signature. Such handlers can retrieve additional parameters from + /// the command, e.g. 'service' indicating where the command should be + /// routed. + /// + /// @param cmd Name of the command to be handled. + /// @param handler Pointer to the method that will handle the command. + void registerExtendedCommand(const std::string& cmd, + ExtendedCommandHandler handler); + + /// @brief Deregisters specified command handler. + /// + /// @param cmd Name of the command that's no longer handled. + void deregisterCommand(const std::string& cmd); + + /// @brief Auxiliary method that removes all installed commands. + /// + /// The only unwipeable method is list-commands, which is internally + /// handled at all times. + void deregisterAll(); + +protected: + + /// @brief Handles the command having a given name and arguments. + /// + /// This method can be overridden in the derived classes to provide + /// custom logic for processing commands. For example, the + /// @ref HookedCommandMgr extends this method to delegate commands + /// processing to a hook library. + /// + /// @param cmd_name Command name. + /// @param params Command arguments. + /// @param original_cmd Pointer to the entire command received. It may + /// be sometimes useful to retrieve additional parameters from this + /// command. + /// + /// @return Pointer to the const data element representing response + /// to a command. + virtual isc::data::ConstElementPtr + handleCommand(const std::string& cmd_name, + const isc::data::ConstElementPtr& params, + const isc::data::ConstElementPtr& original_cmd); + + struct HandlersPair { + CommandHandler handler; + ExtendedCommandHandler extended_handler; + }; + + /// @brief Type of the container for command handlers. + typedef std::map<std::string, HandlersPair> HandlerContainer; + + /// @brief Container for command handlers. + HandlerContainer handlers_; + +private: + + /// @brief 'list-commands' command handler. + /// + /// This method implements command 'list-commands'. It returns a list of all + /// currently supported commands. + /// + /// @param name Name of the command (should always be 'list-commands'). + /// @param params Additional parameters (ignored). + /// + /// @return Pointer to the structure that includes all currently supported + /// commands. + isc::data::ConstElementPtr + listCommandsHandler(const std::string& name, + const isc::data::ConstElementPtr& params); +}; + +} // end of namespace isc::config +} // end of namespace isc + +#endif |