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- //
- // icmp_header.hpp
- // ~~~~~~~~~~~~~~~
- //
- // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- //
- // Distributed under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- //
- #ifndef ICMP_HEADER_HPP
- #define ICMP_HEADER_HPP
- #include <istream>
- #include <ostream>
- #include <algorithm>
- // ICMP header for both IPv4 and IPv6.
- //
- // The wire format of an ICMP header is:
- //
- // 0 8 16 31
- // +---------------+---------------+------------------------------+ ---
- // | | | | ^
- // | type | code | checksum | |
- // | | | | |
- // +---------------+---------------+------------------------------+ 8 bytes
- // | | | |
- // | identifier | sequence number | |
- // | | | v
- // +-------------------------------+------------------------------+ ---
- class icmp_header
- {
- public:
- enum { echo_reply = 0, destination_unreachable = 3, source_quench = 4,
- redirect = 5, echo_request = 8, time_exceeded = 11, parameter_problem = 12,
- timestamp_request = 13, timestamp_reply = 14, info_request = 15,
- info_reply = 16, address_request = 17, address_reply = 18 };
- icmp_header() { std::fill(rep_, rep_ + sizeof(rep_), 0); }
- unsigned char type() const { return rep_[0]; }
- unsigned char code() const { return rep_[1]; }
- unsigned short checksum() const { return decode(2, 3); }
- unsigned short identifier() const { return decode(4, 5); }
- unsigned short sequence_number() const { return decode(6, 7); }
- void type(unsigned char n) { rep_[0] = n; }
- void code(unsigned char n) { rep_[1] = n; }
- void checksum(unsigned short n) { encode(2, 3, n); }
- void identifier(unsigned short n) { encode(4, 5, n); }
- void sequence_number(unsigned short n) { encode(6, 7, n); }
- friend std::istream& operator>>(std::istream& is, icmp_header& header)
- { return is.read(reinterpret_cast<char*>(header.rep_), 8); }
- friend std::ostream& operator<<(std::ostream& os, const icmp_header& header)
- { return os.write(reinterpret_cast<const char*>(header.rep_), 8); }
- private:
- unsigned short decode(int a, int b) const
- { return (rep_[a] << 8) + rep_[b]; }
- void encode(int a, int b, unsigned short n)
- {
- rep_[a] = static_cast<unsigned char>(n >> 8);
- rep_[b] = static_cast<unsigned char>(n & 0xFF);
- }
- unsigned char rep_[8];
- };
- template <typename Iterator>
- void compute_checksum(icmp_header& header,
- Iterator body_begin, Iterator body_end)
- {
- unsigned int sum = (header.type() << 8) + header.code()
- + header.identifier() + header.sequence_number();
- Iterator body_iter = body_begin;
- while (body_iter != body_end)
- {
- sum += (static_cast<unsigned char>(*body_iter++) << 8);
- if (body_iter != body_end)
- sum += static_cast<unsigned char>(*body_iter++);
- }
- sum = (sum >> 16) + (sum & 0xFFFF);
- sum += (sum >> 16);
- header.checksum(static_cast<unsigned short>(~sum));
- }
- #endif // ICMP_HEADER_HPP
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