ethernet-protocol.cpp
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2014-2024, Regents of the University of California,
4  * Arizona Board of Regents,
5  * Colorado State University,
6  * University Pierre & Marie Curie, Sorbonne University,
7  * Washington University in St. Louis,
8  * Beijing Institute of Technology,
9  * The University of Memphis.
10  *
11  * This file is part of NFD (Named Data Networking Forwarding Daemon).
12  * See AUTHORS.md for complete list of NFD authors and contributors.
13  *
14  * NFD is free software: you can redistribute it and/or modify it under the terms
15  * of the GNU General Public License as published by the Free Software Foundation,
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25 
26 #include "ethernet-protocol.hpp"
27 
28 #include <boost/endian/conversion.hpp>
29 
30 namespace nfd::ethernet {
31 
32 std::tuple<const ether_header*, std::string>
33 checkFrameHeader(span<const uint8_t> packet, const Address& localAddr, const Address& destAddr)
34 {
35  if (packet.size() < HDR_LEN + MIN_DATA_LEN)
36  return {nullptr, "Received frame too short: " + std::to_string(packet.size()) + " bytes"};
37 
38  const ether_header* eh = reinterpret_cast<const ether_header*>(packet.data());
39 
40  // in some cases VLAN-tagged frames may survive the BPF filter,
41  // make sure we do not process those frames (see #3348)
42  uint16_t ethertype = boost::endian::big_to_native(eh->ether_type);
43  if (ethertype != ETHERTYPE_NDN)
44  return {nullptr, "Received frame with wrong ethertype: " + std::to_string(ethertype)};
45 
46 #ifndef NDEBUG
47  Address shost(eh->ether_shost);
48  if (shost == localAddr)
49  return {nullptr, "Received frame sent by this host"};
50 
51  Address dhost(eh->ether_dhost);
52  if (dhost != destAddr)
53  return {nullptr, "Received frame addressed to another host or multicast group: " + dhost.toString()};
54 #endif
55 
56  return {eh, ""};
57 }
58 
59 } // namespace nfd::ethernet
std::tuple< const ether_header *, std::string > checkFrameHeader(span< const uint8_t > packet, const Address &localAddr, const Address &destAddr)