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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2013-2018 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
* ndn-cxx library is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later version.
*
* ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
*
* You should have received copies of the GNU General Public License and GNU Lesser
* General Public License along with ndn-cxx, e.g., in COPYING.md file. If not, see
* <http://www.gnu.org/licenses/>.
*
* See AUTHORS.md for complete list of ndn-cxx authors and contributors.
*/
#ifndef NDN_ENCODING_TLV_HPP
#define NDN_ENCODING_TLV_HPP
#include "buffer.hpp"
#include "endian.hpp"
#include <cstring>
#include <iterator>
#include <ostream>
#include <type_traits>
namespace ndn {
/** @brief practical limit of network layer packet size
*
* If a packet is longer than this size, library and application MAY drop it.
*/
const size_t MAX_NDN_PACKET_SIZE = 8800;
/**
* @brief Namespace defining NDN Packet Format related constants and procedures
*/
namespace tlv {
/** @brief represents an error in TLV encoding or decoding
*
* Element::Error SHOULD inherit from this Error class.
*/
class Error : public std::runtime_error
{
public:
explicit
Error(const std::string& what)
: std::runtime_error(what)
{
}
};
/** @brief TLV-TYPE numbers defined in NDN Packet Format v0.3
* @sa https://named-data.net/doc/NDN-packet-spec/current/types.html
*/
enum {
Interest = 5,
Data = 6,
Name = 7,
GenericNameComponent = 8,
ImplicitSha256DigestComponent = 1,
CanBePrefix = 33,
MustBeFresh = 18,
ForwardingHint = 30,
Nonce = 10,
InterestLifetime = 12,
HopLimit = 34,
Parameters = 35,
MetaInfo = 20,
Content = 21,
SignatureInfo = 22,
SignatureValue = 23,
ContentType = 24,
FreshnessPeriod = 25,
FinalBlockId = 26,
SignatureType = 27,
KeyLocator = 28,
KeyDigest = 29,
LinkDelegation = 31,
LinkPreference = 30,
NameComponentMin = 1,
NameComponentMax = 65535,
AppPrivateBlock1 = 128,
AppPrivateBlock2 = 32767
};
/** @brief TLV-TYPE numbers defined in NDN Packet Format v0.2 but not in v0.3
* @sa https://named-data.net/doc/NDN-packet-spec/0.2.1/types.html
*/
enum {
Selectors = 9,
MinSuffixComponents = 13,
MaxSuffixComponents = 14,
PublisherPublicKeyLocator = 15,
Exclude = 16,
ChildSelector = 17,
Any = 19,
};
constexpr int NameComponent NDN_CXX_DEPRECATED = GenericNameComponent;
enum SignatureTypeValue : uint16_t {
DigestSha256 = 0,
SignatureSha256WithRsa = 1,
// <Unassigned> = 2,
SignatureSha256WithEcdsa = 3
};
std::ostream&
operator<<(std::ostream& os, SignatureTypeValue signatureType);
/** @brief TLV-TYPE numbers for SignatureInfo features
* @sa docs/tutorials/certificate-format.rst
*/
enum {
ValidityPeriod = 253,
NotBefore = 254,
NotAfter = 255,
AdditionalDescription = 258,
DescriptionEntry = 512,
DescriptionKey = 513,
DescriptionValue = 514
};
/** @brief indicates a possible value of ContentType field
*/
enum ContentTypeValue {
/** @brief indicates content is the actual data bits
*/
ContentType_Blob = 0,
/** @brief indicates content is another name which identifies actual data content
*/
ContentType_Link = 1,
/** @brief indicates content is a public key
*/
ContentType_Key = 2,
/** @brief indicates a producer generated NACK
*/
ContentType_Nack = 3
};
/**
* @brief Determine whether a TLV-TYPE is "critical" for evolvability purpose.
* @sa https://named-data.net/doc/NDN-packet-spec/0.3/tlv.html#considerations-for-evolvability-of-tlv-based-encoding
*/
constexpr bool
isCriticalType(uint32_t type)
{
return type <= 31 || (type & 0x01);
}
/**
* @brief Read VAR-NUMBER in NDN-TLV encoding
* @tparam Iterator an iterator or pointer whose value is assignable to uint8_t
*
* @param [inout] begin Begin of the buffer, will be incremented to point to the first byte after
* the read VAR-NUMBER
* @param [in] end End of the buffer
* @param [out] number Read VAR-NUMBER
*
* @return true if number was successfully read from input, false otherwise
* @note This call never throws exceptions
*/
template<typename Iterator>
bool
readVarNumber(Iterator& begin, const Iterator& end, uint64_t& number);
/**
* @brief Read TLV-TYPE
* @tparam Iterator an iterator or pointer whose value is assignable to uint8_t
*
* @param [inout] begin Begin of the buffer, will be incremented to point to the first byte after
* the read TLV-TYPE
* @param [in] end End of the buffer
* @param [out] type Read TLV-TYPE
*
* @return true if TLV-TYPE was successfully read from input, false otherwise
* @note This call never throws exceptions
* @note This call is largely equivalent to tlv::readVarNumber, but it will return false if type
* is larger than 2^32-1 (TLV-TYPE in this library is implemented as uint32_t)
*/
template<typename Iterator>
bool
readType(Iterator& begin, const Iterator& end, uint32_t& type);
/**
* @brief Read VAR-NUMBER in NDN-TLV encoding
* @tparam Iterator an iterator or pointer whose value is assignable to uint8_t
*
* @param [inout] begin Begin of the buffer, will be incremented to point to the first byte after
* the read VAR-NUMBER
* @param [in] end End of the buffer
*
* @throw tlv::Error VAR-NUMBER cannot be read
*/
template<typename Iterator>
uint64_t
readVarNumber(Iterator& begin, const Iterator& end);
/**
* @brief Read TLV Type
* @tparam Iterator an iterator or pointer whose value is assignable to uint8_t
*
* @param [inout] begin Begin of the buffer, will be incremented to point to the first byte after
* the read TLV-TYPE
* @param [in] end End of the buffer
*
* @throw tlv::Error VAR-NUMBER cannot be read
* @note This call is largely equivalent to tlv::readVarNumber, but exception will be thrown if type
* is larger than 2^32-1 (TLV-TYPE in this library is implemented as uint32_t)
*/
template<typename Iterator>
uint32_t
readType(Iterator& begin, const Iterator& end);
/**
* @brief Get number of bytes necessary to hold value of VAR-NUMBER
*/
constexpr size_t
sizeOfVarNumber(uint64_t number);
/**
* @brief Write VAR-NUMBER to the specified stream
* @return length of written VAR-NUMBER
*/
size_t
writeVarNumber(std::ostream& os, uint64_t number);
/**
* @brief Read nonNegativeInteger in NDN-TLV encoding
* @tparam Iterator an iterator or pointer whose value is assignable to uint8_t
*
* @param [in] size size of the nonNegativeInteger
* @param [inout] begin Begin of the buffer, will be incremented to point to the first byte after
* the read nonNegativeInteger
* @param [in] end End of the buffer
*
* @throw tlv::Error number cannot be read
* @note How many bytes to read is directly controlled by \p size, which can be either 1, 2, 4, or 8.
* If \p size differs from \p std::distance(begin, end), tlv::Error exception will be thrown.
*/
template<typename Iterator>
uint64_t
readNonNegativeInteger(size_t size, Iterator& begin, const Iterator& end);
/**
* @brief Get number of bytes necessary to hold value of nonNegativeInteger
*/
constexpr size_t
sizeOfNonNegativeInteger(uint64_t integer);
/**
* @brief Write nonNegativeInteger to the specified stream
* @return length of written nonNegativeInteger
*/
size_t
writeNonNegativeInteger(std::ostream& os, uint64_t integer);
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
// Inline definitions
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
namespace detail {
/** @brief Function object to read a number from InputIterator
*/
template<typename Iterator>
class ReadNumberSlow
{
public:
bool
operator()(size_t size, Iterator& begin, const Iterator& end, uint64_t& number) const
{
number = 0;
size_t count = 0;
for (; begin != end && count < size; ++begin, ++count) {
number = (number << 8) | *begin;
}
return count == size;
}
};
/** @brief Function object to read a number from ContiguousIterator
*/
template<typename Iterator>
class ReadNumberFast
{
public:
bool
operator()(size_t size, Iterator& begin, const Iterator& end, uint64_t& number) const
{
if (begin + size > end) {
return false;
}
switch (size) {
case 1: {
number = *begin;
++begin;
return true;
}
case 2: {
uint16_t value = 0;
std::memcpy(&value, &*begin, 2);
begin += 2;
number = be16toh(value);
return true;
}
case 4: {
uint32_t value = 0;
std::memcpy(&value, &*begin, 4);
begin += 4;
number = be32toh(value);
return true;
}
case 8: {
uint64_t value = 0;
std::memcpy(&value, &*begin, 8);
begin += 8;
number = be64toh(value);
return true;
}
default: {
BOOST_ASSERT(false);
return false;
}
}
}
};
/** @brief Determine whether to select ReadNumber implementation for ContiguousIterator
*
* This is not a full ContiguousIterator detection implementation. It returns true for the most
* common ContiguousIterator types used with TLV decoding function templates.
*/
template<typename Iterator,
typename DecayedIterator = typename std::decay<Iterator>::type,
typename ValueType = typename std::iterator_traits<DecayedIterator>::value_type>
constexpr bool
shouldSelectContiguousReadNumber()
{
return (std::is_convertible<DecayedIterator, const ValueType*>::value ||
std::is_convertible<DecayedIterator, typename std::basic_string<ValueType>::const_iterator>::value ||
std::is_convertible<DecayedIterator, typename std::vector<ValueType>::const_iterator>::value) &&
sizeof(ValueType) == 1 &&
!std::is_same<ValueType, bool>::value;
}
template<typename Iterator>
class ReadNumber : public std::conditional<shouldSelectContiguousReadNumber<Iterator>(),
ReadNumberFast<Iterator>, ReadNumberSlow<Iterator>>::type
{
};
} // namespace detail
template<typename Iterator>
bool
readVarNumber(Iterator& begin, const Iterator& end, uint64_t& number)
{
if (begin == end)
return false;
uint8_t firstOctet = *begin;
++begin;
if (firstOctet < 253) {
number = firstOctet;
return true;
}
size_t size = firstOctet == 253 ? 2 :
firstOctet == 254 ? 4 : 8;
return detail::ReadNumber<Iterator>()(size, begin, end, number);
}
template<typename Iterator>
bool
readType(Iterator& begin, const Iterator& end, uint32_t& type)
{
uint64_t number = 0;
bool isOk = readVarNumber(begin, end, number);
if (!isOk || number > std::numeric_limits<uint32_t>::max()) {
return false;
}
type = static_cast<uint32_t>(number);
return true;
}
template<typename Iterator>
uint64_t
readVarNumber(Iterator& begin, const Iterator& end)
{
if (begin == end)
BOOST_THROW_EXCEPTION(Error("Empty buffer during TLV processing"));
uint64_t value = 0;
bool isOk = readVarNumber(begin, end, value);
if (!isOk) {
BOOST_THROW_EXCEPTION(Error("Insufficient data during TLV processing"));
}
return value;
}
template<typename Iterator>
uint32_t
readType(Iterator& begin, const Iterator& end)
{
uint64_t type = readVarNumber(begin, end);
if (type > std::numeric_limits<uint32_t>::max()) {
BOOST_THROW_EXCEPTION(Error("TLV-TYPE number exceeds allowed maximum"));
}
return static_cast<uint32_t>(type);
}
constexpr size_t
sizeOfVarNumber(uint64_t number)
{
return number < 253 ? 1 :
number <= std::numeric_limits<uint16_t>::max() ? 3 :
number <= std::numeric_limits<uint32_t>::max() ? 5 : 9;
}
inline size_t
writeVarNumber(std::ostream& os, uint64_t number)
{
if (number < 253) {
os.put(static_cast<char>(number));
return 1;
}
else if (number <= std::numeric_limits<uint16_t>::max()) {
os.put(static_cast<char>(253));
uint16_t value = htobe16(static_cast<uint16_t>(number));
os.write(reinterpret_cast<const char*>(&value), 2);
return 3;
}
else if (number <= std::numeric_limits<uint32_t>::max()) {
os.put(static_cast<char>(254));
uint32_t value = htobe32(static_cast<uint32_t>(number));
os.write(reinterpret_cast<const char*>(&value), 4);
return 5;
}
else {
os.put(static_cast<char>(255));
uint64_t value = htobe64(number);
os.write(reinterpret_cast<const char*>(&value), 8);
return 9;
}
}
template<typename Iterator>
uint64_t
readNonNegativeInteger(size_t size, Iterator& begin, const Iterator& end)
{
if (size != 1 && size != 2 && size != 4 && size != 8) {
BOOST_THROW_EXCEPTION(Error("Invalid length for nonNegativeInteger "
"(only 1, 2, 4, and 8 are allowed)"));
}
uint64_t number = 0;
bool isOk = detail::ReadNumber<Iterator>()(size, begin, end, number);
if (!isOk) {
BOOST_THROW_EXCEPTION(Error("Insufficient data during TLV processing"));
}
return number;
}
constexpr size_t
sizeOfNonNegativeInteger(uint64_t integer)
{
return integer <= std::numeric_limits<uint8_t>::max() ? 1 :
integer <= std::numeric_limits<uint16_t>::max() ? 2 :
integer <= std::numeric_limits<uint32_t>::max() ? 4 : 8;
}
inline size_t
writeNonNegativeInteger(std::ostream& os, uint64_t integer)
{
if (integer <= std::numeric_limits<uint8_t>::max()) {
os.put(static_cast<char>(integer));
return 1;
}
else if (integer <= std::numeric_limits<uint16_t>::max()) {
uint16_t value = htobe16(static_cast<uint16_t>(integer));
os.write(reinterpret_cast<const char*>(&value), 2);
return 2;
}
else if (integer <= std::numeric_limits<uint32_t>::max()) {
uint32_t value = htobe32(static_cast<uint32_t>(integer));
os.write(reinterpret_cast<const char*>(&value), 4);
return 4;
}
else {
uint64_t value = htobe64(integer);
os.write(reinterpret_cast<const char*>(&value), 8);
return 8;
}
}
} // namespace tlv
} // namespace ndn
#endif // NDN_ENCODING_TLV_HPP