Junxiao Shi
df3b438c40
FragIndex and FragCount fields are encoded as nonNegativeInteger. refs #1283 Change-Id: I4654078c3bfd73c83ce06ce6a9cd97952a4f49f8
113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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/**
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* Copyright (C) 2014 Named Data Networking Project
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* See COPYING for copyright and distribution information.
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*/
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#include "ndnlp-slicer.hpp"
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#include <ndn-cpp-dev/encoding/encoding-buffer.hpp>
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namespace nfd {
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namespace ndnlp {
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Slicer::Slicer(size_t mtu)
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: m_mtu(mtu)
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{
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this->estimateOverhead();
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}
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Slicer::~Slicer()
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{
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}
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template<bool T>
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static inline size_t
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Slicer_encodeFragment(ndn::EncodingImpl<T>& blk,
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uint64_t seq, uint16_t fragIndex, uint16_t fragCount,
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const uint8_t* payload, size_t payloadSize)
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{
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size_t totalLength = 0;
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// NdnlpPayload
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size_t payloadLength = blk.prependByteArray(payload, payloadSize);
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totalLength += payloadLength;
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totalLength += blk.prependVarNumber(payloadLength);
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totalLength += blk.prependVarNumber(tlv::NdnlpPayload);
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bool needFragIndexAndCount = fragCount > 1;
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if (needFragIndexAndCount) {
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// NdnlpFragCount
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size_t fragCountLength = blk.prependNonNegativeInteger(fragCount);
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totalLength += fragCountLength;
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totalLength += blk.prependVarNumber(fragCountLength);
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totalLength += blk.prependVarNumber(tlv::NdnlpFragCount);
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// NdnlpFragIndex
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size_t fragIndexLength = blk.prependNonNegativeInteger(fragIndex);
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totalLength += fragIndexLength;
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totalLength += blk.prependVarNumber(fragIndexLength);
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totalLength += blk.prependVarNumber(tlv::NdnlpFragIndex);
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}
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// NdnlpSequence
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uint64_t sequenceBE = htobe64(seq);
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size_t sequenceLength = blk.prependByteArray(
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reinterpret_cast<uint8_t*>(&sequenceBE), sizeof(sequenceBE));
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totalLength += sequenceLength;
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totalLength += blk.prependVarNumber(sequenceLength);
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totalLength += blk.prependVarNumber(tlv::NdnlpSequence);
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// NdnlpData
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totalLength += blk.prependVarNumber(totalLength);
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totalLength += blk.prependVarNumber(tlv::NdnlpData);
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return totalLength;
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}
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void
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Slicer::estimateOverhead()
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{
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ndn::EncodingEstimator estimator;
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size_t estimatedSize = Slicer_encodeFragment(estimator,
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0, 0, 2, 0, m_mtu);
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size_t overhead = estimatedSize - m_mtu;
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m_maxPayload = m_mtu - overhead;
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}
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PacketArray
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Slicer::slice(const Block& block)
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{
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BOOST_ASSERT(block.hasWire());
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const uint8_t* networkPacket = block.wire();
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size_t networkPacketSize = block.size();
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uint16_t fragCount = static_cast<uint16_t>(
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(networkPacketSize / m_maxPayload) +
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(networkPacketSize % m_maxPayload == 0 ? 0 : 1)
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);
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PacketArray pa = make_shared<std::vector<Block> >();
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pa->reserve(fragCount);
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SequenceBlock seqBlock = m_seqgen.nextBlock(fragCount);
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for (uint16_t fragIndex = 0; fragIndex < fragCount; ++fragIndex) {
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size_t payloadOffset = fragIndex * m_maxPayload;
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const uint8_t* payload = networkPacket + payloadOffset;
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size_t payloadSize = std::min(m_maxPayload, networkPacketSize - payloadOffset);
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ndn::EncodingBuffer buffer(m_mtu, 0);
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size_t pktSize = Slicer_encodeFragment(buffer,
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seqBlock[fragIndex], fragIndex, fragCount, payload, payloadSize);
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BOOST_ASSERT(pktSize <= m_mtu);
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pa->push_back(buffer.block());
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}
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return pa;
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}
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} // namespace ndnlp
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} // namespace nfd
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