src/name-component.cpp

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2013-2014 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 <jefft0@remap.ucla.edu>
 * @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
 * @author Zhenkai Zhu <http://irl.cs.ucla.edu/~zhenkai/>
 */

#include "name-component.hpp"

#include "encoding/block-helpers.hpp"
#include "encoding/encoding-buffer.hpp"
#include "util/string-helper.hpp"

namespace ndn {
namespace name {

Component::Component()
  : Block(tlv::NameComponent)
{
}

Component::Component(const Block& wire)
  : Block(wire)
{
  if (type() != tlv::NameComponent)
    throw Error("Cannot construct name::Component from not a NameComponent TLV wire block");
}

Component::Component(const ConstBufferPtr& buffer)
  : Block(tlv::NameComponent, buffer)
{
}

Component::Component(const Buffer& value)
  : Block(dataBlock(tlv::NameComponent, value.buf(), value.size()))
{
}

Component::Component(const uint8_t* value, size_t valueLen)
  : Block(dataBlock(tlv::NameComponent, value, valueLen))
{
}

Component::Component(const char* str)
  : Block(dataBlock(tlv::NameComponent, str, ::strlen(str)))
{
}

Component::Component(const std::string& str)
  : Block(dataBlock(tlv::NameComponent, str.c_str(), str.size()))
{
}


Component
Component::fromEscapedString(const char* escapedString, size_t beginOffset, size_t endOffset)
{
  std::string trimmedString(escapedString + beginOffset, escapedString + endOffset);
  trim(trimmedString);
  std::string value = unescape(trimmedString);

  if (value.find_first_not_of(".") == std::string::npos) {
    // Special case for component of only periods.
    if (value.size() <= 2)
      // Zero, one or two periods is illegal.  Ignore this component.
      throw Error("Illegal URI (name component cannot be . or ..)");
    else
      // Remove 3 periods.
      return Component(reinterpret_cast<const uint8_t*>(&value[3]), value.size() - 3);
  }
  else
    return Component(reinterpret_cast<const uint8_t*>(&value[0]), value.size());
}


void
Component::toUri(std::ostream& result) const
{
  const uint8_t* value = this->value();
  size_t valueSize = value_size();

  bool gotNonDot = false;
  for (size_t i = 0; i < valueSize; ++i) {
    if (value[i] != 0x2e) {
      gotNonDot = true;
      break;
    }
  }
  if (!gotNonDot) {
    // Special case for component of zero or more periods.  Add 3 periods.
    result << "...";
    for (size_t i = 0; i < valueSize; ++i)
      result << '.';
  }
  else {
    // In case we need to escape, set to upper case hex and save the previous flags.
    std::ios::fmtflags saveFlags = result.flags(std::ios::hex | std::ios::uppercase);

    for (size_t i = 0; i < valueSize; ++i) {
      uint8_t x = value[i];
      // Check for 0-9, A-Z, a-z, (+), (-), (.), (_)
      if ((x >= 0x30 && x <= 0x39) || (x >= 0x41 && x <= 0x5a) ||
          (x >= 0x61 && x <= 0x7a) || x == 0x2b || x == 0x2d ||
          x == 0x2e || x == 0x5f)
        result << x;
      else {
        result << '%';
        if (x < 16)
          result << '0';
        result << static_cast<uint32_t>(x);
      }
    }

    // Restore.
    result.flags(saveFlags);
  }
}

std::string
Component::toUri() const
{
  std::ostringstream os;
  toUri(os);
  return os.str();
}

uint64_t
Component::toNumber() const
{
  /// \todo Check if Component is of tlv::NumberComponent type
  return readNonNegativeInteger(*this);
}

uint64_t
Component::toNumberWithMarker(uint8_t marker) const
{
  if (empty() || value()[0] != marker)
    throw Error("Name component does not have the requested marker");

  Buffer::const_iterator valueBegin = value_begin() + 1;
  return tlv::readNonNegativeInteger(value_size() - 1, valueBegin, value_end());
}

uint64_t
Component::toVersion() const
{
  return toNumberWithMarker(VERSION_MARKER);
}

uint64_t
Component::toSegment() const
{
  return toNumberWithMarker(SEGMENT_MARKER);
}

uint64_t
Component::toSegmentOffset() const
{
  return toNumberWithMarker(SEGMENT_OFFSET_MARKER);
}

time::system_clock::TimePoint
Component::toTimestamp() const
{
  uint64_t value = toNumberWithMarker(TIMESTAMP_MARKER);
  return time::getUnixEpoch() + time::microseconds(value);
}

uint64_t
Component::toSequenceNumber() const
{
  return toNumberWithMarker(SEQUENCE_NUMBER_MARKER);
}


Component
Component::fromNumber(uint64_t number)
{
  /// \todo Change to tlv::NumberComponent
  return nonNegativeIntegerBlock(tlv::NameComponent, number);
}

Component
Component::fromNumberWithMarker(uint8_t marker, uint64_t number)
{
  EncodingEstimator estimator;

  size_t valueLength = estimator.prependNonNegativeInteger(number);
  valueLength += estimator.prependByteArray(&marker, 1);
  size_t totalLength = valueLength;
  totalLength += estimator.prependVarNumber(valueLength);
  totalLength += estimator.prependVarNumber(tlv::NameComponent);

  EncodingBuffer encoder(totalLength, 0);
  encoder.prependNonNegativeInteger(number);
  encoder.prependByteArray(&marker, 1);
  encoder.prependVarNumber(valueLength);
  encoder.prependVarNumber(tlv::NameComponent);

  return encoder.block();
}

Component
Component::fromVersion(uint64_t version)
{
  return fromNumberWithMarker(VERSION_MARKER, version);
}

Component
Component::fromSegment(uint64_t segmentNo)
{
  return fromNumberWithMarker(SEGMENT_MARKER, segmentNo);
}

Component
Component::fromSegmentOffset(uint64_t offset)
{
  return fromNumberWithMarker(SEGMENT_OFFSET_MARKER, offset);
}

Component
Component::fromTimestamp(const time::system_clock::TimePoint& timePoint)
{
  using namespace time;
  uint64_t value = duration_cast<microseconds>(timePoint - getUnixEpoch()).count();
  return fromNumberWithMarker(TIMESTAMP_MARKER, value);
}

Component
Component::fromSequenceNumber(uint64_t seqNo)
{
  return fromNumberWithMarker(SEQUENCE_NUMBER_MARKER, seqNo);
}

int
Component::compare(const Component& other) const
{
  // Imitate ndn_Exclude_compareComponents.
  if (value_size() < other.value_size())
    return -1;
  if (value_size() > other.value_size())
    return 1;

  if (value_size() == 0)
    return 0;

  // The components are equal length.  Just do a byte compare.
  return std::memcmp(value(), other.value(), value_size());
}

Component
Component::getSuccessor() const
{
  size_t totalLength = 0;
  EncodingBuffer encoder(size() + 1, 1); // + 1 in case there is an overflow
                                         // in unlikely case TLV length increases,
                                         // EncodingBuffer will take care of that

  bool isOverflow = true;
  size_t i = value_size();
  for (; isOverflow && i > 0; i--) {
    uint8_t newValue = static_cast<uint8_t>((value()[i - 1] + 1) & 0xFF);
    totalLength += encoder.prependByte(newValue);
    isOverflow = (newValue == 0);
  }
  totalLength += encoder.prependByteArray(value(), i);

  if (isOverflow) {
    // new name components has to be extended
    totalLength += encoder.appendByte(0);
  }

  totalLength += encoder.prependVarNumber(totalLength);
  totalLength += encoder.prependVarNumber(tlv::NameComponent);

  return encoder.block();
}


template<bool T>
size_t
Component::wireEncode(EncodingImpl<T>& block) const
{
  size_t totalLength = 0;
  if (value_size() > 0)
    totalLength += block.prependByteArray(value(), value_size());
  totalLength += block.prependVarNumber(value_size());
  totalLength += block.prependVarNumber(tlv::NameComponent);
  return totalLength;
}

template size_t
Component::wireEncode<true>(EncodingImpl<true>& block) const;

template size_t
Component::wireEncode<false>(EncodingImpl<false>& block) const;

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) = buffer.block();
  return *this;
}

void
Component::wireDecode(const Block& wire)
{
  if (wire.type() != tlv::NameComponent)
    throw Error("name::Component::wireDecode called on not a NameComponent TLV wire block");

  *this = wire;
}

} // namespace name
} // namespace ndn