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| -rw-r--r-- | src/lib/dns/rrclass-placeholder.h | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/src/lib/dns/rrclass-placeholder.h b/src/lib/dns/rrclass-placeholder.h new file mode 100644 index 0000000..9804c57 --- /dev/null +++ b/src/lib/dns/rrclass-placeholder.h @@ -0,0 +1,312 @@ +// Copyright (C) 2010-2017 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 RRCLASS_H +#define RRCLASS_H 1 + +#include <stdint.h> + +#include <string> +#include <ostream> + +#include <dns/exceptions.h> + +#include <boost/optional.hpp> + +// Undefine the macro IN which is defined in some operating systems +// but conflicts the IN RR class. + +#ifdef IN +#undef IN +#endif + +namespace isc { +namespace util { +class InputBuffer; +class OutputBuffer; +} + +namespace dns { + +// forward declarations +class AbstractMessageRenderer; + +/// +/// \brief A standard DNS module exception that is thrown if an RRClass object +/// is being constructed from an unrecognized string. +/// +class InvalidRRClass : public DNSTextError { +public: + InvalidRRClass(const char* file, size_t line, const char* what) : + DNSTextError(file, line, what) {} +}; + +/// +/// \brief A standard DNS module exception that is thrown if an RRClass object +/// is being constructed from a incomplete (too short) wire-format data. +/// +class IncompleteRRClass : public isc::dns::Exception { +public: + IncompleteRRClass(const char* file, size_t line, const char* what) : + isc::dns::Exception(file, line, what) {} +}; + +/// +/// The \c RRClass class encapsulates DNS resource record classes. +/// +/// This class manages the 16-bit integer class codes in quite a straightforward +/// way. The only non trivial task is to handle textual representations of +/// RR classes, such as "IN", "CH", or "CLASS65534". +/// +/// This class consults a helper \c RRParamRegistry class, which is a registry +/// of RR related parameters and has the singleton object. This registry +/// provides a mapping between RR class codes and their "well-known" textual +/// representations. +/// Parameters of RR classes defined by DNS protocol standards are automatically +/// registered at initialization time and are ensured to be always available for +/// applications unless the application explicitly modifies the registry. +/// +/// For convenience, this class defines constant class objects corresponding to +/// standard RR classes. These are generally referred to as the form of +/// <code>RRClass::{class-text}()</code>. +/// For example, \c RRClass::IN() is an \c RRClass object corresponding to the +/// IN class (class code 1). +/// Note that these constants are used through a "proxy" function. +/// This is because they may be used to initialize another non-local (e.g. +/// global or namespace-scope) static object as follows: +/// +/// \code +/// namespace foo { +/// const RRClass default_class = RRClass::IN(); +/// } \endcode +/// +/// In order to ensure that the constant RRClass object has been initialized +/// before the initialization for \c default_class, we need help from +/// the proxy function. +/// +/// Note to developers: same note as \c RRType applies. +class RRClass { +public: + /// + /// \name Constructors and Destructor + /// + //@{ + /// Constructor from an integer class code. + /// + /// This constructor never throws an exception. + /// + /// \param classcode An 16-bit integer code corresponding to the RRClass. + explicit RRClass(uint16_t classcode) : classcode_(classcode) {} + /// + /// A valid string is one of "well-known" textual class representations + /// such as "IN" or "CH", or in the standard format for "unknown" + /// classes as defined in RFC3597, i.e., "CLASSnnnn". + /// + /// More precisely, the "well-known" representations are the ones stored + /// in the \c RRParamRegistry registry (see the class description). + /// + /// As for the format of "CLASSnnnn", "nnnn" must represent a valid 16-bit + /// unsigned integer, which may contain leading 0's as long as it consists + /// of at most 5 characters (inclusive). + /// For example, "CLASS1" and "CLASS0001" are valid and represent the same + /// class, but "CLASS65536" and "CLASS000001" are invalid. + /// A "CLASSnnnn" representation is valid even if the corresponding class + /// code is registered in the \c RRParamRegistry object. For example, both + /// "IN" and "CLASS1" are valid and represent the same class. + /// + /// All of these representations are case insensitive; "IN" and "in", and + /// "CLASS1" and "class1" are all valid and represent the same classes, + /// respectively. + /// + /// If the given string is not recognized as a valid representation of + /// an RR class, an exception of class \c InvalidRRClass will be thrown. + /// + /// \param class_str A string representation of the \c RRClass + explicit RRClass(const std::string& class_str); + /// Constructor from wire-format data. + /// + /// The \c buffer parameter normally stores a complete DNS message + /// containing the RRClass to be constructed. The current read position of + /// the buffer points to the head of the class. + /// + /// If the given data does not large enough to contain a 16-bit integer, + /// an exception of class \c IncompleteRRClass will be thrown. + /// + /// \param buffer A buffer storing the wire format data. + explicit RRClass(isc::util::InputBuffer& buffer); + + /// A separate factory of RRClass from text. + /// + /// This static method is similar to the constructor that takes a + /// string object, but works as a factory and reports parsing + /// failure in the form of the return value. Normally the + /// constructor version should suffice, but in some cases the caller + /// may have to expect mixture of valid and invalid input, and may + /// want to minimize the overhead of possible exception handling. + /// This version is provided for such purpose. + /// + /// For the format of the \c class_str argument, see the + /// <code>RRClass(const std::string&)</code> constructor. + /// + /// If the given text represents a valid RRClass, it returns a + /// pointer to a new \c RRClass object. If the given text does not + /// represent a valid RRClass, it returns \c NULL. + /// + /// One main purpose of this function is to minimize the overhead + /// when the given text does not represent a valid RR class. For + /// this reason this function intentionally omits the capability of + /// delivering a detailed reason for the parse failure, such as in the + /// \c want() string when exception is thrown from the constructor + /// (it will internally require a creation of string object, which + /// is relatively expensive). If such detailed information is + /// necessary, the constructor version should be used to catch the + /// resulting exception. + /// + /// This function never throws the \c InvalidRRClass exception. + /// + /// \param class_str A string representation of the \c RRClass. + /// \return A new RRClass object for the given text or a \c NULL + /// value. + static RRClass* createFromText(const std::string& class_str); + + /// + /// We use the default copy constructor intentionally. + //@} + /// We use the default copy assignment operator intentionally. + /// + + /// + /// \name Converter methods + /// + //@{ + /// \brief Convert the \c RRClass to a string. + /// + /// If a "well known" textual representation for the class code is + /// registered in the RR parameter registry (see the class description), + /// that will be used as the return value of this method. Otherwise, this + /// method creates a new string for an "unknown" class in the format defined + /// in RFC3597, i.e., "CLASSnnnn", and returns it. + /// + /// If resource allocation for the string fails, a corresponding standard + /// exception will be thrown. + /// + /// \return A string representation of the \c RRClass. + const std::string toText() const; + /// \brief Render the \c RRClass in the wire format. + /// + /// This method renders the class code in network byte order via + /// \c renderer, which encapsulates output buffer and other rendering + /// contexts. + /// + /// If resource allocation in rendering process fails, a corresponding + /// standard exception will be thrown. + /// + /// \param renderer DNS message rendering context that encapsulates the + /// output buffer in which the RRClass is to be stored. + void toWire(AbstractMessageRenderer& renderer) const; + /// \brief Render the \c RRClass in the wire format. + /// + /// This method renders the class code in network byte order into the + /// \c buffer. + /// + /// If resource allocation in rendering process fails, a corresponding + /// standard exception will be thrown. + /// + /// \param buffer An output buffer to store the wire data. + void toWire(isc::util::OutputBuffer& buffer) const; + //@} + + /// + /// \name Getter Methods + /// + //@{ + /// \brief Returns the RR class code as a 16-bit unsigned integer. + /// + /// This method never throws an exception. + /// + /// \return An 16-bit integer code corresponding to the RRClass. + uint16_t getCode() const { return (classcode_); } + //@} + + /// + /// \name Comparison methods + /// + //@{ + /// \brief Return true iff two RRClasses are equal. + /// + /// Two RRClasses are equal iff their class codes are equal. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRClass object to compare against. + /// \return true if the two RRClasses are equal; otherwise false. + bool equals(const RRClass& other) const + { return (classcode_ == other.classcode_); } + /// \brief Same as \c equals(). + bool operator==(const RRClass& other) const { return (equals(other)); } + + /// \brief Return true iff two RRClasses are not equal. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRClass object to compare against. + /// \return true if the two RRClasses are not equal; otherwise false. + bool nequals(const RRClass& other) const + { return (classcode_ != other.classcode_); } + /// \brief Same as \c nequals(). + bool operator!=(const RRClass& other) const { return (nequals(other)); } + + /// \brief Less-than comparison for RRClass against \c other + /// + /// We define the less-than relationship based on their class codes; + /// one RRClass is less than the other iff the code of the former is less + /// than that of the other as unsigned integers. + /// The relationship is meaningless in terms of DNS protocol; the only + /// reason we define this method is that RRClass objects can be stored in + /// STL containers without requiring user-defined less-than relationship. + /// We therefore don't define other comparison operators. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRClass object to compare against. + /// \return true if \c this RRClass is less than the \c other; otherwise + /// false. + bool operator<(const RRClass& other) const + { return (classcode_ < other.classcode_); } + + // BEGIN_WELL_KNOWN_CLASS_DECLARATIONS + // END_WELL_KNOWN_CLASS_DECLARATIONS + +private: + uint16_t classcode_; +}; + +// BEGIN_WELL_KNOWN_CLASS_DEFINITIONS +// END_WELL_KNOWN_CLASS_DEFINITIONS + +/// +/// \brief Insert the \c RRClass as a string into stream. +/// +/// This method convert the \c rrclass into a string and inserts it into the +/// output stream \c os. +/// +/// This function overloads the global operator<< to behave as described in +/// ostream::operator<< but applied to \c RRClass objects. +/// +/// \param os A \c std::ostream object on which the insertion operation is +/// performed. +/// \param rrclass The \c RRClass object output by the operation. +/// \return A reference to the same \c std::ostream object referenced by +/// parameter \c os after the insertion operation. +std::ostream& +operator<<(std::ostream& os, const RRClass& rrclass); +} +} +#endif // RRCLASS_H + +// Local Variables: +// mode: c++ +// End: |