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| -rw-r--r-- | src/lib/dns/rrttl.h | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/src/lib/dns/rrttl.h b/src/lib/dns/rrttl.h new file mode 100644 index 0000000..abda3e5 --- /dev/null +++ b/src/lib/dns/rrttl.h @@ -0,0 +1,306 @@ +// Copyright (C) 2010-2015 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 RRTTL_H +#define RRTTL_H 1 + +#include <dns/exceptions.h> + +#include <boost/optional.hpp> + +#include <stdint.h> + +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 RRTTL object +/// is being constructed from an unrecognized string. +/// +class InvalidRRTTL : public DNSTextError { +public: + InvalidRRTTL(const char* file, size_t line, const char* what) : + DNSTextError(file, line, what) {} +}; + +/// +/// \brief A standard DNS module exception that is thrown if an RRTTL object +/// is being constructed from a incomplete (too short) wire-format data. +/// +class IncompleteRRTTL : public isc::dns::Exception { +public: + IncompleteRRTTL(const char* file, size_t line, const char* what) : + isc::dns::Exception(file, line, what) {} +}; + +/// +/// The \c RRTTL class encapsulates TTLs used in DNS resource records. +/// +/// This is a straightforward class; an \c RRTTL object simply maintains a +/// 32-bit unsigned integer corresponding to the TTL value. The main purpose +/// of this class is to provide convenient interfaces to convert a textual +/// representation into the integer TTL value and vice versa, and to handle +/// wire-format representations. +class RRTTL { +public: + /// + /// \name Constructors, Factory and Destructor + /// + /// Note: We use the default copy constructor and the default copy + /// assignment operator intentionally. + //@{ + /// Constructor from an integer TTL value. + /// + /// This constructor never throws an exception. + /// + /// \param ttlval An 32-bit integer of the RRTTL. + explicit RRTTL(uint32_t ttlval) : ttlval_(ttlval) {} + + /// Constructor from a string. + /// + /// It accepts either a decimal number, specifying number of seconds. Or, + /// it can be given a sequence of numbers and units, like "2H" (meaning + /// two hours), "1W3D" (one week and 3 days). The allowed units are W + /// (week), D (day), H (hour), M (minute) and S (second). They can be also + /// specified in lower-case. No further restrictions are checked (so they + /// can be specified in arbitrary order and even things like "1D1D" can + /// be used to specify two days). + /// + /// \param ttlstr A string representation of the \c RRTTL. + /// + /// \throw InvalidRRTTL in case the string is not recognized as valid + /// TTL representation. + explicit RRTTL(const std::string& ttlstr); + + /// Constructor from wire-format data. + /// + /// The \c buffer parameter normally stores a complete DNS message + /// containing the RRTTL to be constructed. The current read position of + /// the buffer points to the head of the type. + /// + /// If the given data does not large enough to contain a 16-bit integer, + /// an exception of class \c IncompleteRRTTL will be thrown. + /// + /// \param buffer A buffer storing the wire format data. + explicit RRTTL(isc::util::InputBuffer& buffer); + + /// A separate factory of RRTTL 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. + /// + /// If the given text represents a valid RRTTL, it returns a pointer + /// to a new RRTTL object. If the given text does not represent a + /// valid RRTTL, 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 TTL. 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 InvalidRRTTL exception. + /// + /// \param ttlstr A string representation of the \c RRTTL. + /// \return A new RRTTL object for the given text or a \c NULL value. + static RRTTL* createFromText(const std::string& ttlstr); + /// + //@} + + /// + /// \name Converter methods + /// + //@{ + /// \brief Convert the \c RRTTL to a string. + /// + /// This version of implementation simply converts the TTL value into the + /// numeric textual representation. We may introduce more human-readable + /// format depending on the context in future versions. + /// + /// If resource allocation in rendering process fails, a corresponding + /// standard exception will be thrown. + /// + /// \return A string representation of the \c RRTTL. + const std::string toText() const; + /// \brief Render the \c RRTTL in the wire format. + /// + /// This method renders the TTL value 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 RRTTL is to be stored. + void toWire(AbstractMessageRenderer& renderer) const; + /// \brief Render the \c RRTTL in the wire format. + /// + /// This method renders the TTL value 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 TTL value as a 32-bit unsigned integer. + /// + /// This method never throws an exception. + /// + /// \return An 32-bit integer corresponding to the RRTTL. + uint32_t getValue() const { return (ttlval_); } + //@} + + /// + /// \name Comparison methods + /// + /// Comparison between two \c RRTTL objects is performed in a + /// straightforward way, that is, comparing the corresponding TTL values + /// (which is the result of the \c getValue() method) as 32-bit unsigned + /// integers. + //@{ + /// \brief Return true iff two RRTTLs are equal. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRTTL object to compare against. + bool equals(const RRTTL& other) const + { return (ttlval_ == other.ttlval_); } + /// \brief Same as \c equals(). + bool operator==(const RRTTL& other) const + { return (ttlval_ == other.ttlval_); } + /// \brief Return true iff two RRTTLs are not equal. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRTTL object to compare against. + bool nequals(const RRTTL& other) const + { return (ttlval_ != other.ttlval_); } + /// \brief Same as \c nequals(). + bool operator!=(const RRTTL& other) const + { return (ttlval_ != other.ttlval_); } + /// \brief Less-than or equal comparison for RRTTL against \c other. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRTTL object to compare against. + /// \return true if \c this RRTTL is less than or equal to the \c other; + /// otherwise false. + bool leq(const RRTTL& other) const + { return (ttlval_ <= other.ttlval_); } + + /// Same as \c leq() + bool operator<=(const RRTTL& other) const + { return (ttlval_ <= other.ttlval_); } + + /// \brief Greater-than or equal comparison for RRTTL against \c other. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRTTL object to compare against. + /// \return true if \c this RRTTL is greater than or equal to the \c other; + /// otherwise false. + bool geq(const RRTTL& other) const + { return (ttlval_ >= other.ttlval_); } + + /// Same as \c geq() + bool operator>=(const RRTTL& other) const + { return (ttlval_ >= other.ttlval_); } + + /// \brief Less-than comparison for RRTTL against \c other. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRTTL object to compare against. + /// \return true if \c this RRTTL is less than the \c other; + /// otherwise false. + bool lthan(const RRTTL& other) const + { return (ttlval_ < other.ttlval_); } + + /// Same as \c lthan() + bool operator<(const RRTTL& other) const + { return (ttlval_ < other.ttlval_); } + + /// \brief Greater-than comparison for RRTTL against \c other. + /// + /// This method never throws an exception. + /// + /// \param other the \c RRTTL object to compare against. + /// \return true if \c this RRTTL is greater than the \c other; + /// otherwise false. + bool gthan(const RRTTL& other) const + { return (ttlval_ > other.ttlval_); } + + /// Same as \c gthan() + bool operator>(const RRTTL& other) const + { return (ttlval_ > other.ttlval_); } + //@} + + /// + /// \name Protocol constants + /// + //@{ + /// \brief The TTL of the max allowable value, per RFC2181 Section 8. + /// + /// The max value is the largest unsigned 31 bit integer, 2^31-1. + /// + /// \note At the moment an RRTTL object can have a value larger than + /// this limit. We may revisit it in a future version. + static const RRTTL& MAX_TTL() { + static const RRTTL max_ttl(0x7fffffff); + return (max_ttl); + } + //@} + +private: + uint32_t ttlval_; +}; + +/// +/// \brief Insert the \c RRTTL as a string into stream. +/// +/// This method convert the \c rrttl 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 RRTTL objects. +/// +/// \param os A \c std::ostream object on which the insertion operation is +/// performed. +/// \param rrttl The \c RRTTL 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 RRTTL& rrttl); +} +} +#endif // RRTTL_H + +// Local Variables: +// mode: c++ +// End: |