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diff --git a/src/lib/process/d_controller.h b/src/lib/process/d_controller.h new file mode 100644 index 0000000..e16253e --- /dev/null +++ b/src/lib/process/d_controller.h @@ -0,0 +1,663 @@ +// Copyright (C) 2013-2023 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 D_CONTROLLER_H +#define D_CONTROLLER_H + +#include <asiolink/io_service.h> +#include <asiolink/io_service_signal.h> +#include <cc/data.h> +#include <exceptions/exceptions.h> +#include <log/logger_support.h> +#include <process/daemon.h> +#include <process/d_log.h> +#include <process/d_process.h> + +#include <boost/shared_ptr.hpp> +#include <boost/noncopyable.hpp> + +#include <string> +#include <set> + +namespace isc { +namespace process { + +/// @brief Exception thrown when the command line is invalid. +/// Can be used to transmit negative messages too. +class InvalidUsage : public isc::Exception { +public: + InvalidUsage(const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Exception used to convey version info upwards. +/// Since command line argument parsing is done as part of +/// DControllerBase::launch(), it uses this exception to propagate +/// version information up to main(), when command line argument +/// -v, -V or -W is given. Can be used to transmit positive messages too. +class VersionMessage : public isc::Exception { +public: + VersionMessage(const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Exception thrown when the controller launch fails. +class LaunchError: public isc::Exception { +public: + LaunchError (const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Exception thrown when the application process fails. +class ProcessInitError: public isc::Exception { +public: + ProcessInitError (const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Exception thrown when the application process encounters an +/// operation in its event loop (i.e. run method). +class ProcessRunError: public isc::Exception { +public: + ProcessRunError (const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Exception thrown when the controller encounters an operational error. +class DControllerBaseError : public isc::Exception { +public: + DControllerBaseError (const char* file, size_t line, const char* what) : + isc::Exception(file, line, what) { }; +}; + +/// @brief Defines a shared pointer to DControllerBase. +class DControllerBase; +typedef boost::shared_ptr<DControllerBase> DControllerBasePtr; + +/// @brief Application Controller +/// +/// DControllerBase is an abstract singleton which provides the framework and +/// services for managing an application process that implements the +/// DProcessBase interface. It runs the process like a stand-alone, command +/// line driven executable, which must be supplied a configuration file at +/// startup. It coordinates command line argument parsing, process +/// instantiation and initialization, and runtime control through external +/// command and configuration event handling. +/// It creates the IOService instance which is used for runtime control +/// events and passes the IOService into the application process at process +/// creation. +/// It provides the callback handlers for command and configuration events +/// which could be triggered by an external source. Such sources are intended +/// to be registered with and monitored by the controller's IOService such that +/// the appropriate handler can be invoked. +/// +/// DControllerBase provides dynamic configuration file reloading upon receipt +/// of SIGHUP, and graceful shutdown upon receipt of either SIGINT or SIGTERM. +/// +/// NOTE: Derivations must supply their own static singleton instance method(s) +/// for creating and fetching the instance. The base class declares the instance +/// member in order for it to be available for static callback functions. +class DControllerBase : public Daemon { +public: + /// @brief Constructor + /// + /// @param app_name is display name of the application under control. This + /// name appears in log statements. + /// @param bin_name is the name of the application executable. + DControllerBase(const char* app_name, const char* bin_name); + + /// @brief Destructor + virtual ~DControllerBase(); + + /// @brief returns Kea version on stdout and exit. + /// redeclaration/redefinition. @ref isc::process::Daemon::getVersion() + std::string getVersion(bool extended); + + /// @brief Acts as the primary entry point into the controller execution + /// and provides the outermost application control logic: + /// + /// 1. parse command line arguments + /// 2. instantiate and initialize the application process + /// 3. load the configuration file + /// 4. record the start timestamp + /// 5. initialize signal handling + /// 6. start and wait on the application process event loop + /// 7. exit to the caller + /// + /// It is intended to be called from main() and be given the command line + /// arguments. + /// + /// This function can be run in "test mode". It prevents initialization + /// of module logger. This is used in unit tests which initialize logger + /// in their main function. Such a logger uses environmental variables to + /// control severity, verbosity etc. + /// + /// @param argc is the number of command line arguments supplied + /// @param argv is the array of string (char *) command line arguments + /// @param test_mode is a bool value which indicates if + /// @c DControllerBase::launch should be run in the test mode (if true). + /// This parameter doesn't have default value to force test implementers to + /// enable test mode explicitly. + /// + /// @throw throws one of the following exceptions: + /// InvalidUsage - Indicates invalid command line. + /// ProcessInitError - Failed to create and initialize application + /// process object. + /// ProcessRunError - A fatal error occurred while in the application + /// process event loop. + /// @return The value from @c Daemon::getExitValue(). + virtual int launch(int argc, char* argv[], const bool test_mode); + + /// @brief Instance method invoked by the configuration event handler and + /// which processes the actual configuration update. Provides behavioral + /// path for both integrated and stand-alone modes. The current + /// implementation will merge the configuration update into the existing + /// configuration and then invoke the application process' configure method. + /// + /// @param new_config is the new configuration + /// + /// @return returns an Element that contains the results of configuration + /// update composed of an integer status value (0 means successful, + /// non-zero means failure), and a string explanation of the outcome. + virtual isc::data::ConstElementPtr updateConfig(isc::data::ConstElementPtr + new_config); + + /// @brief Instance method invoked by the configuration event handler and + /// which processes the actual configuration check. Provides behavioral + /// path for both integrated and stand-alone modes. The current + /// implementation will merge the configuration update into the existing + /// configuration and then invoke the application process' configure method + /// with a final rollback. + /// + /// @param new_config is the new configuration + /// + /// @return returns an Element that contains the results of configuration + /// update composed of an integer status value (0 means successful, + /// non-zero means failure), and a string explanation of the outcome. + virtual isc::data::ConstElementPtr checkConfig(isc::data::ConstElementPtr + new_config); + + /// @brief Reconfigures the process from a configuration file + /// + /// By default the file is assumed to be a JSON text file whose contents + /// include at least: + /// + /// @code + /// { "<module-name>": {<module-config>} + /// } + /// + /// where: + /// module-name : is a label which uniquely identifies the + /// configuration data for this controller's application + /// + /// module-config: a set of zero or more JSON elements which comprise + /// the application's configuration values + /// @endcode + /// + /// To translate the JSON content into Elements, @c parseFile() is called + /// first. This virtual method provides derivations a means to parse the + /// file content using an alternate parser. If it returns an empty pointer + /// than the JSON parsing providing by Element::fromJSONFile() is called. + /// + /// Once parsed, the method extracts the set of configuration + /// elements for the module-name that matches the controller's app_name_, + /// looks for the loggers entry and, if present uses it to configure + /// logging. It then passes that set into @c updateConfig() (or + /// @c checkConfig()). + /// + /// The file may contain an arbitrary number of other modules. + /// + /// @return returns an Element that contains the results of configuration + /// update composed of an integer status value (0 means successful, + /// non-zero means failure), and a string explanation of the outcome. + virtual isc::data::ConstElementPtr configFromFile(); + + /// @brief Fetches the name of the application under control. + /// + /// @return returns the controller service name string + std::string getAppName() const { + return (app_name_); + } + + /// @brief Fetches the name of the application executable. + /// + /// @return returns the controller logger name string + std::string getBinName() const { + return (bin_name_); + } + + /// @brief handler for version-get command + /// + /// This method handles the version-get command. It returns the basic and + /// extended version. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return answer with version details. + isc::data::ConstElementPtr + versionGetHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for 'build-report' command + /// + /// This method handles build-report command. It returns the output printed + /// by configure script which contains most compilation parameters. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return answer with build report + isc::data::ConstElementPtr + buildReportHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for config-get command + /// + /// This method handles the config-get command, which retrieves + /// the current configuration and returns it in response. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return current configuration wrapped in a response + isc::data::ConstElementPtr + configGetHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for config-hash-get command + /// + /// This method handles the config-hash-get command, which retrieves + /// the current configuration and returns it in response. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return hash of current configuration wrapped in a response + isc::data::ConstElementPtr + configHashGetHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for config-write command + /// + /// This handle processes write-config command, which writes the + /// current configuration to disk. This command takes one optional + /// parameter called filename. If specified, the current configuration + /// will be written to that file. If not specified, the file used during + /// Kea start-up will be used. To avoid any exploits, the path is + /// always relative and .. is not allowed in the filename. This is + /// a security measure against exploiting file writes remotely. + /// + /// @param command (ignored) + /// @param args may contain optional string argument filename + /// @return status of the configuration file write + isc::data::ConstElementPtr + configWriteHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for config-test command + /// + /// This method handles the config-test command, which checks + /// configuration specified in args parameter. + /// + /// @param command (ignored) + /// @param args configuration to be checked. + /// @return status of the command + isc::data::ConstElementPtr + configTestHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for config-reload command + /// + /// This method handles the config-reload command, which reloads + /// the configuration file. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return status of the command + isc::data::ConstElementPtr + configReloadHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for config-set command + /// + /// This method handles the config-set command, which loads + /// configuration specified in args parameter. + /// + /// @param command (ignored) + /// @param args configuration to be checked. + /// @return status of the command + isc::data::ConstElementPtr + configSetHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for 'shutdown' command + /// + /// This method handles shutdown command. It initiates the shutdown procedure + /// using CPL methods. + /// @param command (ignored) + /// @param args (ignored) + /// @return answer confirming that the shutdown procedure is started + isc::data::ConstElementPtr + shutdownHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for server-tag-get command + /// + /// This method handles the server-tag-get command, which retrieves + /// the current server tag and returns it in response. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return current configuration wrapped in a response + isc::data::ConstElementPtr + serverTagGetHandler(const std::string& command, + isc::data::ConstElementPtr args); + + /// @brief handler for status-get command + /// + /// This method handles the status-get command, which retrieves + /// the server process information i.e. the pid and returns it in + /// response. + /// + /// @param command (ignored) + /// @param args (ignored) + /// @return process information wrapped in a response + isc::data::ConstElementPtr + statusGetHandler(const std::string& command, + isc::data::ConstElementPtr args); + +protected: + /// @brief Virtual method that provides derivations the opportunity to + /// support additional command line options. It is invoked during command + /// line argument parsing (see parseArgs method) if the option is not + /// recognized as a stock DControllerBase option. + /// + /// @param option is the option "character" from the command line, without + /// any prefixing hyphen(s) + /// @param optarg is the argument value (if one) associated with the option + /// + /// @return must return true if the option was valid, false if it is + /// invalid. (Note the default implementation always returns false.) + virtual bool customOption(int option, char *optarg); + + /// @brief Abstract method that is responsible for instantiating the + /// application process object. It is invoked by the controller after + /// command line argument parsing as part of the process initialization + /// (see initProcess method). + /// + /// @return returns a pointer to the new process object (DProcessBase*) + /// or NULL if the create fails. + /// Note this value is subsequently wrapped in a smart pointer. + virtual DProcessBase* createProcess() = 0; + + /// @brief Virtual method which can be used to contribute derivation + /// specific usage text. It is invoked by the usage() method under + /// invalid usage conditions. + /// + /// @return returns the desired text. + virtual const std::string getUsageText() const { + return (""); + } + + /// @brief Virtual method which returns a string containing the option + /// letters for any custom command line options supported by the derivation. + /// These are added to the stock options of "c", "d", ..., during command + /// line interpretation. + /// + /// @return returns a string containing the custom option letters. + virtual const std::string getCustomOpts() const { + return (""); + } + + /// @brief Check the configuration + /// + /// Called by @c launch() when @c check_only_ mode is enabled + /// @throw VersionMessage when successful but a message should be displayed + /// @throw InvalidUsage when an error was detected + void checkConfigOnly(); + + /// @brief Application-level signal processing method. + /// + /// This method is the last step in processing a OS signal occurrence. + /// It currently supports the following signals as follows: + /// -# SIGHUP - instigates reloading the configuration file + /// -# SIGINT - instigates a graceful shutdown + /// -# SIGTERM - instigates a graceful shutdown + /// If it receives any other signal, it will issue a debug statement and + /// discard it. + /// Derivations wishing to support additional signals could override this + /// method with one that: processes the signal if it is one of additional + /// signals, otherwise invoke this method (DControllerBase::processSignal()) + /// with the signal value. + /// @todo Provide a convenient way for derivations to register additional + /// signals. + virtual void processSignal(int signum); + + /// @brief Supplies whether or not verbose logging is enabled. + /// + /// @return returns true if verbose logging is enabled. + bool isVerbose() const { + return (verbose_); + } + + /// @brief Method for enabling or disabling verbose logging. + /// + /// @param value is the new value to assign the flag. + void setVerbose(bool value) { + verbose_ = value; + } + + /// @brief Supplies whether or not check only mode is enabled. + /// + /// @return returns true if check only is enabled. + bool isCheckOnly() const { + return (check_only_); + } + + /// @brief Method for enabling or disabling check only mode. + /// + /// @todo this method and @c setVerbose are currently not used. + /// + /// @param value is the new value to assign the flag. + void setCheckOnly(bool value) { + check_only_ = value; + } + + /// @brief Getter for fetching the controller's IOService + /// + /// @return returns a pointer reference to the IOService. + asiolink::IOServicePtr& getIOService() { + return (io_service_); + } + + /// @brief Static getter which returns the singleton instance. + /// + /// @return returns a pointer reference to the private singleton instance + /// member. + static DControllerBasePtr& getController() { + return (controller_); + } + + /// @brief Static setter which sets the singleton instance. + /// + /// @param controller is a pointer to the singleton instance. + /// + /// @throw throws DControllerBase error if an attempt is made to set the + /// instance a second time. + static void setController(const DControllerBasePtr& controller); + + /// @brief Processes the command line arguments. It is the first step + /// taken after the controller has been launched. It combines the stock + /// list of options with those returned by getCustomOpts(), and uses + /// cstdlib's getopt to loop through the command line. + /// It handles stock options directly, and passes any custom options into + /// the customOption method. Currently there are only some stock options + /// -c/t for specifying the configuration file, -d for verbose logging, + /// and -v/V/W for version reports. + /// + /// @param argc is the number of command line arguments supplied + /// @param argv is the array of string (char *) command line arguments + /// + /// @throw InvalidUsage when there are usage errors. + /// @throw VersionMessage if the -v, -V or -W arguments is given. + void parseArgs(int argc, char* argv[]); + + ///@brief Parse a given file into Elements + /// + /// This method provides a means for deriving classes to use alternate + /// parsing mechanisms to parse configuration files into the corresponding + /// isc::data::Elements. The elements produced must be equivalent to those + /// which would be produced by the original JSON parsing. Implementations + /// should throw when encountering errors. + /// + /// The default implementation returns an empty pointer, signifying to + /// callers that they should submit the file to the original parser. + /// + /// @param file_name pathname of the file to parse + /// + /// @return pointer to the elements created + /// + virtual isc::data::ConstElementPtr parseFile(const std::string& file_name); + + ///@brief Parse text into Elements + /// + /// This method provides a means for deriving classes to use alternate + /// parsing mechanisms to parse configuration text into the corresponding + /// isc::data::Elements. The elements produced must be equivalent to those + /// which would be produced by the original JSON parsing. Implementations + /// should throw when encountering errors. + /// + /// The default implementation returns an empty pointer, signifying to + /// callers that they should submit the text to the original parser. + /// + /// @param input text to parse + /// + /// @return pointer to the elements created + /// + virtual isc::data::ConstElementPtr parseText(const std::string& input) { + static_cast<void>(input); // just tu shut up the unused parameter warning + isc::data::ConstElementPtr elements; + return (elements); + } + + /// @brief Instantiates the application process and then initializes it. + /// This is the second step taken during launch, following successful + /// command line parsing. It is used to invoke the derivation-specific + /// implementation of createProcess, following by an invoking of the + /// newly instantiated process's init method. + /// + /// @throw throws DControllerBaseError or indirectly DProcessBaseError + /// if there is a failure creating or initializing the application process. + void initProcess(); + + /// @brief Invokes the application process's event loop,(DBaseProcess::run). + /// It is called during launch only after successfully completing the + /// requested setup: command line parsing, application initialization, + /// and session establishment (if not stand-alone). + /// The process event loop is expected to only return upon application + /// shutdown either in response to the shutdown command or due to an + /// unrecoverable error. + /// + // @throw throws DControllerBaseError or indirectly DProcessBaseError + void runProcess(); + + /// @brief Initiates shutdown procedure. This method is invoked + /// by executeCommand in response to the shutdown command. It will invoke + /// the application process's shutdown method which causes the process to + /// to begin its shutdown process. + /// + /// Note, it is assumed that the process of shutting down is neither + /// instantaneous nor synchronous. This method does not "block" waiting + /// until the process has halted. Rather it is used to convey the + /// need to shutdown. A successful return indicates that the shutdown + /// has successfully commenced, but does not indicate that the process + /// has actually exited. + /// + /// @return returns an Element that contains the results of shutdown + /// command composed of an integer status value (0 means successful, + /// non-zero means failure), and a string explanation of the outcome. + /// + /// @param args is a set of derivation-specific arguments (if any) + /// for the shutdown command. + isc::data::ConstElementPtr shutdownProcess(isc::data::ConstElementPtr args); + + /// @brief Initializes signal handling + /// + /// This method configures the controller to catch and handle signals. + /// It instantiates a IOSignalSet which listens for SIGHUP, SIGINT, and + /// SIGTERM. + void initSignalHandling(); + + /// @brief Fetches the current process + /// + /// @return a pointer to the current process instance. + DProcessBasePtr getProcess() { + return (process_); + } + + /// @brief Prints the program usage text to std error. + /// + /// @param text is a string message which will preceded the usage text. + /// This is intended to be used for specific usage violation messages. + void usage(const std::string& text); + + /// @brief Fetches text containing additional version specifics + /// + /// This method is provided so derivations can append any additional + /// desired information such as library dependencies to the extended + /// version text returned when DControllerBase::getVersion(true) is + /// invoked. + /// @return a string containing additional version info + virtual std::string getVersionAddendum() { return (""); } + + /// @brief Deals with other (i.e. not application name) global objects. + /// + /// Code shared between configuration handlers: + /// - check obsolete or unknown (aka unsupported) objects. + /// + /// @param args Command arguments. + /// @return Error message or empty string. + std::string handleOtherObjects(isc::data::ConstElementPtr args); + +private: + /// @brief Name of the service under control. + /// This name is used as the configuration module name and appears in log + /// statements. + std::string app_name_; + + /// @brief Name of the service executable. + /// By convention this matches the executable name. It is also used to + /// establish the logger name. + std::string bin_name_; + + /// @brief Indicates if the verbose logging mode is enabled. + bool verbose_; + + /// @brief Indicates if the check only mode for the configuration + /// is enabled (usually specified by the command line -t argument). + bool check_only_; + + /// @brief Pointer to the instance of the process. + /// + /// This is required for config and command handlers to gain access to + /// the process + DProcessBasePtr process_; + + /// @brief Shared pointer to an IOService object, used for ASIO operations. + isc::asiolink::IOServicePtr io_service_; + + /// @brief ASIO signal set. + isc::asiolink::IOSignalSetPtr io_signal_set_; + + /// @brief Singleton instance value. + static DControllerBasePtr controller_; + +// DControllerTest is named a friend class to facilitate unit testing while +// leaving the intended member scopes intact. +friend class DControllerTest; +}; + +} // namespace process +} // namespace isc + +#endif |