Junxiao Shi
48 lines
1.8 KiB
C++
48 lines
1.8 KiB
C++
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
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/**
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* Copyright (c) 2014-2017, Regents of the University of California,
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* Arizona Board of Regents,
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* Colorado State University,
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* University Pierre & Marie Curie, Sorbonne University,
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* Washington University in St. Louis,
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* Beijing Institute of Technology,
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* The University of Memphis.
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*
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* This file is part of NFD (Named Data Networking Forwarding Daemon).
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* See AUTHORS.md for complete list of NFD authors and contributors.
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*
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* NFD is free software: you can redistribute it and/or modify it under the terms
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* of the GNU General Public License as published by the Free Software Foundation,
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* either version 3 of the License, or (at your option) any later version.
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*
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* NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "udp-protocol.hpp"
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namespace nfd {
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namespace udp {
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ssize_t
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computeMtu(const Endpoint& localEndpoint)
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{
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size_t mtu = 0;
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if (localEndpoint.address().is_v4()) { // IPv4
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mtu = std::numeric_limits<uint16_t>::max(); // maximum Total Length
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mtu -= sizeof(uint32_t) * ((1 << 4) - 1); // maximum Internet Header Length
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}
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else { // IPv6
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mtu = std::numeric_limits<uint16_t>::max(); // maximum Payload Length
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}
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mtu -= sizeof(uint16_t) * 4; // size of UDP header
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return mtu;
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}
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} // namespace udp
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} // namespace nfd
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