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| -rw-r--r-- | src/lib/cc/simple_parser.h | 339 |
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diff --git a/src/lib/cc/simple_parser.h b/src/lib/cc/simple_parser.h new file mode 100644 index 0000000..cb78802 --- /dev/null +++ b/src/lib/cc/simple_parser.h @@ -0,0 +1,339 @@ +// Copyright (C) 2016-2022 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 SIMPLE_PARSER_H +#define SIMPLE_PARSER_H + +#include <asiolink/io_address.h> +#include <cc/data.h> +#include <cc/dhcp_config_error.h> +#include <util/triplet.h> +#include <map> +#include <vector> +#include <string> +#include <stdint.h> +#include <limits> + +namespace isc { +namespace data { + +/// This array defines a single entry of default values. +struct SimpleDefault { + SimpleDefault(const char* name, isc::data::Element::types type, const char* value) + :name_(name), type_(type), value_(value) {} + std::string name_; + const isc::data::Element::types type_; + const char* value_; +}; + +/// This specifies all required keywords. +typedef std::vector<std::string> SimpleRequiredKeywords; + +/// This specifies all accepted keywords with their types. +typedef std::map<std::string, isc::data::Element::types> SimpleKeywords; + +/// This specifies all default values in a given scope (e.g. a subnet). +typedef std::vector<SimpleDefault> SimpleDefaults; + +/// This defines a list of all parameters that are derived (or inherited) between +/// contexts. +typedef std::vector<std::string> ParamsList; + + +/// @brief A simple parser +/// +/// This class is intended to be a simpler replacement for DhcpConfigParser. +/// This class has been initially created to facilitate DHCPv4 and +/// DHCPv6 servers' configuration parsing. Thus examples provided +/// herein are related to DHCP configuration. Nevertheless, this is a +/// generic class to be used in other modules too. +/// +/// The simplification comes from several factors: +/// - no build/commit nonsense. There's a single step: +/// CfgStorage parse(ConstElementPtr json) +/// that converts JSON configuration into an object and returns it. +/// - no state kept. This greatly simplifies the parsers (no contexts, no child +/// parsers list, no separate storage for uint32, strings etc. In fact, +/// this base class is purely static. However, some derived classes may store +/// some state. Implementors are advised to store as little state as possible. +/// - no optional parameters (all are mandatory). This simplifies the parser, +/// but introduces a new step before parsing where we insert the default +/// values into client configuration before parsing. This is actually a good +/// thing, because we now have a clear picture of the default parameters as +/// they're defined in a single place (the DhcpConfigParser had the defaults +/// spread out in multiple files in multiple directories). +class SimpleParser { +public: + + /// @brief Checks that all required keywords are present. + /// + /// This method throws an exception when a required + /// entry is not present in the given scope. + /// + /// @param required Required keywords. + /// @param scope Specified parameters which are checked. + /// @throw DhcpConfigError if a required parameter is not present. + static void checkRequired(const SimpleRequiredKeywords& required, + isc::data::ConstElementPtr scope); + + /// @brief Checks acceptable keywords with their expected type. + /// + /// This methods throws an exception when a not acceptable keyword + /// is found or when an acceptable entry does not have the expected type. + /// + /// @param keywords The @c SimpleKeywords keywords and types map. + /// @param scope Specified parameters which are checked. + /// @throw DhcpConfigError if a not acceptable keyword is found. + /// @throw DhcpConfigError if an acceptable entry does not have + /// the expected type. + static void checkKeywords(const SimpleKeywords& keywords, + isc::data::ConstElementPtr scope); + + /// @brief Derives (inherits) parameters from parent scope to a child + /// + /// This method derives parameters from the parent scope to the child, + /// if there are no values specified in the child scope. For example, + /// this method can be used to derive timers from global scope (e.g. for + /// the whole DHCPv6 server) to a subnet scope. This method checks + /// if the child scope doesn't have more specific values defined. If + /// it doesn't, then the value from parent scope is copied over. + /// + /// @param parent scope to copy from (e.g. global) + /// @param child scope to copy from (e.g. subnet) + /// @param params names of the parameters to copy + /// @return number of parameters copied + static size_t deriveParams(isc::data::ConstElementPtr parent, + isc::data::ElementPtr child, + const ParamsList& params); + + /// @brief Sets the default values + /// + /// This method sets the default values for parameters that are not + /// defined. The list of default values is specified by default_values. + /// If not present, those will be inserted into the scope. If + /// a parameter is already present, the default value will not + /// be inserted. + /// + /// @param scope default values will be inserted here + /// @param default_values list of default values + /// @return number of parameters inserted + static size_t setDefaults(isc::data::ElementPtr scope, + const SimpleDefaults& default_values); + + /// @brief Sets the default values for all entries in a list + /// + /// This is a simple utility method that iterates over all + /// parameters in a list and calls setDefaults for each + /// entry. + /// + /// @param list list to be iterated over + /// @param default_values list of default values + /// @return number of parameters inserted + static size_t setListDefaults(isc::data::ConstElementPtr list, + const SimpleDefaults& default_values); + + /// @brief Utility method that returns position of an element + /// + /// It's mostly useful for logging. If the element is missing + /// the parent position is returned or ZERO_POSITION if parent + /// is null. + /// + /// @param name position of that element will be returned + /// @param parent parent element (optional) + /// @return position of the element specified. + static const data::Element::Position& + getPosition(const std::string& name, const data::ConstElementPtr parent); + + /// @brief Returns a string parameter from a scope + /// + /// Unconditionally returns a parameter. + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return a string value of the parameter + /// @throw DhcpConfigError if the parameter is not there or is not of + /// appropriate type + static std::string getString(isc::data::ConstElementPtr scope, + const std::string& name); + + /// @brief Returns an integer parameter from a scope + /// + /// Unconditionally returns a parameter. + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return an integer value of the parameter + /// @throw DhcpConfigError if the parameter is not there or is not of + /// appropriate type + static int64_t getInteger(isc::data::ConstElementPtr scope, + const std::string& name); + + /// @brief Returns an integer parameter from a scope and checks its range + /// + /// Unconditionally returns a parameter. Checks that the value specified + /// is in min =< X =< max range. + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @param min minimum allowed value + /// @param max maximum allowed value + /// @return an integer value of the parameter + /// @throw DhcpConfigError if the parameter is not there or is not of + /// appropriate type. + /// @throw OutOfRange if the parameter is out of range + static int64_t getInteger(isc::data::ConstElementPtr scope, + const std::string& name, + int64_t min, int64_t max); + + /// @brief Returns a boolean parameter from a scope + /// + /// Unconditionally returns a parameter. + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return a boolean value of the parameter + /// @throw DhcpConfigError if the parameter is not there or is not of + /// appropriate type + static bool getBoolean(isc::data::ConstElementPtr scope, + const std::string& name); + + + /// @brief Returns a IOAddress parameter from a scope + /// + /// Unconditionally returns a parameter. + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return an IOAddress representing the value of the parameter + /// @throw DhcpConfigError if the parameter is not there or is not of + /// appropriate type (or its conversion to IOAddress fails due to not + /// being a proper address). + static isc::asiolink::IOAddress + getAddress(const ConstElementPtr& scope, const std::string& name); + + /// @brief Returns a floating point parameter from a scope + /// + /// Unconditionally returns a parameter. + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return a double value of the parameter + /// @throw DhcpConfigError if the parameter is not there or is not + /// an Element::real + static double getDouble(const ConstElementPtr& scope, + const std::string& name); + +protected: + + /// @brief Returns an integer value with range checking from a scope + /// + /// This template should be instantiated in parsers when useful + /// + /// @tparam int_type the integer type e.g. uint32_t + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter for error report + /// @return a value of int_type + /// @throw DhcpConfigError if the parameter is not there, is not of + /// appropriate type or is out of type value range + template <typename int_type> int_type + getIntType(isc::data::ConstElementPtr scope, + const std::string& name) { + int64_t val_int = getInteger(scope, name); + if ((val_int < std::numeric_limits<int_type>::min()) || + (val_int > std::numeric_limits<int_type>::max())) { + isc_throw(isc::dhcp::DhcpConfigError, + "out of range value (" << val_int + << ") specified for parameter '" << name + << "' (" << getPosition(name, scope) << ")"); + } + return (static_cast<int_type>(val_int)); + } + + /// @brief Returns a converted value from a scope + /// + /// This template should be instantiated in parsers when useful + /// + /// @tparam target_type the type of the result + /// @tparam convert the conversion function std::string -> target_type + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter for error report + /// @param type_name name of target_type for error report + /// @return a converted value of target_type + /// @throw DhcpConfigError if the parameter is not there, is not of + /// appropriate type or can not be converted + template <typename target_type, + target_type convert(const std::string&)> target_type + getAndConvert(isc::data::ConstElementPtr scope, + const std::string& name, + const std::string& type_name) { + std::string str = getString(scope, name); + try { + return (convert(str)); + } catch (const std::exception&) { + isc_throw(isc::dhcp::DhcpConfigError, + "invalid " << type_name << " (" << str + << ") specified for parameter '" << name + << "' (" << getPosition(name, scope) << ")"); + } + } + +public: + /// @brief Returns a value converted to uint32_t + /// + /// Instantiation of getIntType() to uint32_t + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return an uint32_t value + /// @throw isc::dhcp::DhcpConfigError when it is not an uint32_t + uint32_t getUint32(isc::data::ConstElementPtr scope, + const std::string& name) { + return (getIntType<uint32_t>(scope, name)); + } + + /// @brief Returns a value converted to uint16_t + /// + /// Instantiation of getIntType() to uint16_t + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return an uint16_t value + /// @throw isc::dhcp::DhcpConfigError when it is not an uint16_t + uint16_t getUint16(isc::data::ConstElementPtr scope, + const std::string& name) { + return (getIntType<uint16_t>(scope, name)); + } + + /// @brief Get an uint8_t value + /// + /// Instantiation of getIntType() to uint8_t + /// + /// @param scope specified parameter will be extracted from this scope + /// @param name name of the parameter + /// @return uint8_t value + /// @throw isc::dhcp::DhcpConfigError when it is not an uint8_t + uint8_t getUint8(ConstElementPtr scope, const std::string& name) { + return (getIntType<uint8_t>(scope, name)); + } + + /// @brief Parses an integer triplet + /// + /// Parses an integer triplet parameter of the form: + /// + /// min-{name}, {name}, max-{name} + /// + /// @param scope Data element holding e.g. shared network configuration + /// to be parsed. + /// @param name Base name of the parameter. + /// @return A triplet with the parsed value. + const isc::util::Triplet<uint32_t> parseIntTriplet(const data::ConstElementPtr& scope, + const std::string& name); +}; + +} +} + +#endif |