name-component.cpp

Go to the documentation of this file.

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2024 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.
 *
 * @author Jeff Thompson <[email protected]>
 * @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
 * @author Zhenkai Zhu <http://irl.cs.ucla.edu/~zhenkai/>
 */
 
#include "ndn-cxx/name-component.hpp"
#include "ndn-cxx/impl/name-component-types.hpp"
 
#include <cstdlib>
#include <cstring>
#include <sstream>
 
#include <boost/logic/tribool.hpp>
 
namespace ndn::name {
 
static Convention g_conventionEncoding = Convention::TYPED;
static Convention g_conventionDecoding = Convention::EITHER;
 
Convention
getConventionEncoding() noexcept
{
  return g_conventionEncoding;
}
 
void
setConventionEncoding(Convention convention)
{
  switch (convention) {
    case Convention::MARKER:
    case Convention::TYPED:
      g_conventionEncoding = convention;
      break;
    default:
      NDN_THROW(std::invalid_argument("Unknown naming convention"));
  }
}
 
Convention
getConventionDecoding() noexcept
{
  return g_conventionDecoding;
}
 
void
setConventionDecoding(Convention convention)
{
  g_conventionDecoding = convention;
}
 
static bool
canDecodeMarkerConvention() noexcept
{
  return (to_underlying(g_conventionDecoding) & to_underlying(Convention::MARKER)) != 0;
}
 
static bool
canDecodeTypedConvention() noexcept
{
  return (to_underlying(g_conventionDecoding) & to_underlying(Convention::TYPED)) != 0;
}
 
 
Component::Component(uint32_t type)
  : Block(type)
{
  ensureValid();
}
 
Component::Component(const Block& wire)
  : Block(wire)
{
  ensureValid();
}
 
Component::Component(uint32_t type, ConstBufferPtr buffer)
  : Block(type, std::move(buffer))
{
  ensureValid();
}
 
Component::Component(uint32_t type, span<const uint8_t> value)
  : Block(makeBinaryBlock(type, value))
{
  ensureValid();
}
 
Component::Component(std::string_view str)
  : Block(makeStringBlock(tlv::GenericNameComponent, str))
{
}
 
void
Component::ensureValid() const
{
  if (type() < tlv::NameComponentMin || type() > tlv::NameComponentMax) {
    NDN_THROW(Error("TLV-TYPE " + std::to_string(type()) + " is not a valid NameComponent"));
  }
  getComponentTypeTable().get(type()).check(*this);
}
 
static Component
parseUriEscapedValue(uint32_t type, std::string_view input)
{
  std::ostringstream oss;
  unescape(oss, input);
  std::string value = oss.str();
  if (value.find_first_not_of('.') == std::string::npos) { // all periods
    if (value.size() < 3) {
      NDN_THROW(Component::Error("Illegal URI (name component cannot be . or ..)"));
    }
    return Component(type, {reinterpret_cast<const uint8_t*>(value.data()), value.size() - 3});
  }
  return Component(type, {reinterpret_cast<const uint8_t*>(value.data()), value.size()});
}
 
Component
Component::fromUri(std::string_view input)
{
  size_t equalPos = input.find('=');
  if (equalPos == std::string_view::npos) {
    return parseUriEscapedValue(tlv::GenericNameComponent, input);
  }
 
  auto typePrefix = input.substr(0, equalPos);
  auto type = std::strtoul(typePrefix.data(), nullptr, 10);
  if (type >= tlv::NameComponentMin && type <= tlv::NameComponentMax &&
      std::to_string(type) == typePrefix) {
    return parseUriEscapedValue(static_cast<uint32_t>(type), input.substr(equalPos + 1));
  }
 
  auto ct = getComponentTypeTable().findByUriPrefix(typePrefix);
  if (ct == nullptr) {
    NDN_THROW(Error("Unknown TLV-TYPE '" + std::string(typePrefix) + "' in NameComponent URI"));
  }
  return ct->parseAltUriValue(input.substr(equalPos + 1));
}
 
static bool
wantAltUri(UriFormat format)
{
  static const auto wantAltEnv = []() -> boost::tribool {
    const char* env = std::getenv("NDN_NAME_ALT_URI");
    if (env == nullptr)
      return boost::indeterminate;
    else if (env[0] == '0')
      return false;
    else if (env[0] == '1')
      return true;
    else
      return boost::indeterminate;
  }();
 
  if (format == UriFormat::ENV_OR_CANONICAL) {
    static const bool wantAlt = boost::indeterminate(wantAltEnv) ? false : bool(wantAltEnv);
    return wantAlt;
  }
  else if (format == UriFormat::ENV_OR_ALTERNATE) {
    static const bool wantAlt = boost::indeterminate(wantAltEnv) ? true : bool(wantAltEnv);
    return wantAlt;
  }
  else {
    return format == UriFormat::ALTERNATE;
  }
}
 
void
Component::toUri(std::ostream& os, UriFormat format) const
{
  if (wantAltUri(format)) {
    getComponentTypeTable().get(type()).writeUri(os, *this);
  }
  else {
    ComponentType().writeUri(os, *this);
  }
}
 
std::string
Component::toUri(UriFormat format) const
{
  std::ostringstream os;
  toUri(os, format);
  return os.str();
}
 
 
bool
Component::isNumber() const noexcept
{
  return value_size() == 1 || value_size() == 2 ||
         value_size() == 4 || value_size() == 8;
}
 
bool
Component::isNumberWithMarker(uint8_t marker) const noexcept
{
  return (value_size() == 2 || value_size() == 3 ||
          value_size() == 5 || value_size() == 9) && value()[0] == marker;
}
 
bool
Component::isSegment() const noexcept
{
  return (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent && isNumberWithMarker(SEGMENT_MARKER)) ||
         (canDecodeTypedConvention() && type() == tlv::SegmentNameComponent && isNumber());
}
 
bool
Component::isByteOffset() const noexcept
{
  return (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent && isNumberWithMarker(SEGMENT_OFFSET_MARKER)) ||
         (canDecodeTypedConvention() && type() == tlv::ByteOffsetNameComponent && isNumber());
}
 
bool
Component::isVersion() const noexcept
{
  return (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent && isNumberWithMarker(VERSION_MARKER)) ||
         (canDecodeTypedConvention() && type() == tlv::VersionNameComponent && isNumber());
}
 
bool
Component::isTimestamp() const noexcept
{
  return (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent && isNumberWithMarker(TIMESTAMP_MARKER)) ||
         (canDecodeTypedConvention() && type() == tlv::TimestampNameComponent && isNumber());
}
 
bool
Component::isSequenceNumber() const noexcept
{
  return (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent && isNumberWithMarker(SEQUENCE_NUMBER_MARKER)) ||
         (canDecodeTypedConvention() && type() == tlv::SequenceNumNameComponent && isNumber());
}
 
 
uint64_t
Component::toNumber() const
{
  if (!isNumber())
    NDN_THROW(Error("Name component does not have NonNegativeInteger value"));
 
  return readNonNegativeInteger(*this);
}
 
uint64_t
Component::toNumberWithMarker(uint8_t marker) const
{
  if (!isNumberWithMarker(marker))
    NDN_THROW(Error("Name component does not have the requested marker "
                    "or the value is not a NonNegativeInteger"));
 
  auto valueBegin = value_begin() + 1;
  return tlv::readNonNegativeInteger(value_size() - 1, valueBegin, value_end());
}
 
uint64_t
Component::toSegment() const
{
  if (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent) {
    return toNumberWithMarker(SEGMENT_MARKER);
  }
  if (canDecodeTypedConvention() && type() == tlv::SegmentNameComponent) {
    return toNumber();
  }
  NDN_THROW(Error("Not a Segment component"));
}
 
uint64_t
Component::toByteOffset() const
{
  if (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent) {
    return toNumberWithMarker(SEGMENT_OFFSET_MARKER);
  }
  if (canDecodeTypedConvention() && type() == tlv::ByteOffsetNameComponent) {
    return toNumber();
  }
  NDN_THROW(Error("Not a ByteOffset component"));
}
 
uint64_t
Component::toVersion() const
{
  if (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent) {
    return toNumberWithMarker(VERSION_MARKER);
  }
  if (canDecodeTypedConvention() && type() == tlv::VersionNameComponent) {
    return toNumber();
  }
  NDN_THROW(Error("Not a Version component"));
}
 
time::system_clock::time_point
Component::toTimestamp() const
{
  uint64_t value = 0;
  if (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent) {
    value = toNumberWithMarker(TIMESTAMP_MARKER);
  }
  else if (canDecodeTypedConvention() && type() == tlv::TimestampNameComponent) {
    value = toNumber();
  }
  else {
    NDN_THROW(Error("Not a Timestamp component"));
  }
  return time::getUnixEpoch() + time::microseconds(value);
}
 
uint64_t
Component::toSequenceNumber() const
{
  if (canDecodeMarkerConvention() && type() == tlv::GenericNameComponent) {
    return toNumberWithMarker(SEQUENCE_NUMBER_MARKER);
  }
  if (canDecodeTypedConvention() && type() == tlv::SequenceNumNameComponent) {
    return toNumber();
  }
  NDN_THROW(Error("Not a SequenceNumber component"));
}
 
 
Component
Component::fromNumber(uint64_t number, uint32_t type)
{
  return Component(makeNonNegativeIntegerBlock(type, number));
}
 
Component
Component::fromNumberWithMarker(uint8_t marker, uint64_t number)
{
  EncodingEstimator estimator;
  size_t valueLength = estimator.prependNonNegativeInteger(number);
  valueLength += estimator.prependBytes({marker});
  size_t totalLength = valueLength;
  totalLength += estimator.prependVarNumber(valueLength);
  totalLength += estimator.prependVarNumber(tlv::GenericNameComponent);
 
  EncodingBuffer encoder(totalLength, 0);
  encoder.prependNonNegativeInteger(number);
  encoder.prependBytes({marker});
  encoder.prependVarNumber(valueLength);
  encoder.prependVarNumber(tlv::GenericNameComponent);
 
  return Component(encoder.block());
}
 
Component
Component::fromSegment(uint64_t segmentNo)
{
  return g_conventionEncoding == Convention::MARKER ?
         fromNumberWithMarker(SEGMENT_MARKER, segmentNo) :
         fromNumber(segmentNo, tlv::SegmentNameComponent);
}
 
Component
Component::fromByteOffset(uint64_t offset)
{
  return g_conventionEncoding == Convention::MARKER ?
         fromNumberWithMarker(SEGMENT_OFFSET_MARKER, offset) :
         fromNumber(offset, tlv::ByteOffsetNameComponent);
}
 
Component
Component::fromVersion(uint64_t version)
{
  return g_conventionEncoding == Convention::MARKER ?
         fromNumberWithMarker(VERSION_MARKER, version) :
         fromNumber(version, tlv::VersionNameComponent);
}
 
Component
Component::fromTimestamp(const time::system_clock::time_point& timePoint)
{
  uint64_t value = time::duration_cast<time::microseconds>(timePoint - time::getUnixEpoch()).count();
  return g_conventionEncoding == Convention::MARKER ?
         fromNumberWithMarker(TIMESTAMP_MARKER, value) :
         fromNumber(value, tlv::TimestampNameComponent);
}
 
Component
Component::fromSequenceNumber(uint64_t seqNo)
{
  return g_conventionEncoding == Convention::MARKER ?
         fromNumberWithMarker(SEQUENCE_NUMBER_MARKER, seqNo) :
         fromNumber(seqNo, tlv::SequenceNumNameComponent);
}
 
 
bool
Component::isImplicitSha256Digest() const noexcept
{
  return type() == tlv::ImplicitSha256DigestComponent && value_size() == util::Sha256::DIGEST_SIZE;
}
 
bool
Component::isParametersSha256Digest() const noexcept
{
  return type() == tlv::ParametersSha256DigestComponent && value_size() == util::Sha256::DIGEST_SIZE;
}
 
 
int
Component::compare(const Component& other) const
{
  if (this->hasWire() && other.hasWire()) {
    // In the common case where both components have wire encoding,
    // it's more efficient to simply compare the wire encoding.
    // This works because lexical order of TLV encoding happens to be
    // the same as canonical order of the value.
    return std::memcmp(data(), other.data(), std::min(size(), other.size()));
  }
 
  int cmpType = type() - other.type();
  if (cmpType != 0)
    return cmpType;
 
  int cmpSize = value_size() - other.value_size();
  if (cmpSize != 0)
    return cmpSize;
 
  if (empty())
    return 0;
 
  return std::memcmp(value(), other.value(), value_size());
}
 
Component
Component::getSuccessor() const
{
  auto [isOverflow, successor] = getComponentTypeTable().get(type()).getSuccessor(*this);
  if (!isOverflow) {
    return successor;
  }
 
  uint32_t type = this->type() + 1;
  auto value = getComponentTypeTable().get(type).getMinValue();
  return {type, value};
}
 
template<encoding::Tag TAG>
size_t
Component::wireEncode(EncodingImpl<TAG>& encoder) const
{
  size_t totalLength = 0;
  if (value_size() > 0) {
    totalLength += encoder.prependBytes(value_bytes());
  }
  totalLength += encoder.prependVarNumber(value_size());
  totalLength += encoder.prependVarNumber(type());
  return totalLength;
}
 
NDN_CXX_DEFINE_WIRE_ENCODE_INSTANTIATIONS(Component);
 
const Block&
Component::wireEncode() const
{
  if (this->hasWire())
    return *this;
 
  EncodingEstimator estimator;
  size_t estimatedSize = wireEncode(estimator);
 
  EncodingBuffer buffer(estimatedSize, 0);
  wireEncode(buffer);
 
  const_cast<Component*>(this)->wireDecode(buffer.block());
  return *this;
}
 
void
Component::wireDecode(const Block& wire)
{
  *this = Component(wire);
  // validity check is done within Component(const Block& wire)
}
 
} // namespace ndn::name