boost asio icmp实现
1.icmp_header.h
//
// icmp_header.hpp
// ~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2013 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
#include
#include
// 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); }//std::fill 相当于memset
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)//>> 只能声明为友元函数，友元函数实际是全局函数
{ return is.read(reinterpret_cast(header.rep_), 8); }// reinterpret_cast,
friend std::ostream& operator<<(std::ostream& os, const icmp_header& header)
{ return os.write(reinterpret_cast(header.rep_), 8); }
private:
unsigned short decode(int a, int b) const//decode 从字节流编程有意义的东西
{ return (rep_[a] << 8) + rep_[b]; }
void encode(int a, int b, unsigned short n)//encode 变成字节流
{
rep_[a] = static_cast(n >> 8);//unsigned short -> unsigned char
rep_[b] = static_cast(n & 0xFF);
}
unsigned char rep_[8];
};
template
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(*body_iter++) << 8);
if (body_iter != body_end)
sum += static_cast(*body_iter++);
}
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
header.checksum(static_cast(~sum));
}
#endif // ICMP_HEADER_HPP 2. ipv4_header.h
//
// ipv4_header.hpp
// ~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2013 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 IPV4_HEADER_HPP
#define IPV4_HEADER_HPP
#include
#include
// Packet header for IPv4.
//
// The wire format of an IPv4 header is:
//
// 0 8 16 31
// +-------+-------+---------------+------------------------------+ ---
// | | | | | ^
// |version|header | type of | total length in bytes | |
// | (4) | length| service | | |
// +-------+-------+---------------+-+-+-+------------------------+ |
// | | | | | | |
// | identification |0|D|M| fragment offset | |
// | | |F|F| | |
// +---------------+---------------+-+-+-+------------------------+ |
// | | | | |
// | time to live | protocol | header checksum | 20 bytes
// | | | | |
// +---------------+---------------+------------------------------+ |
// | | |
// | source IPv4 address | |
// | | |
// +--------------------------------------------------------------+ |
// | | |
// | destination IPv4 address | |
// | | v
// +--------------------------------------------------------------+ ---
// | | ^
// | | |
// / options (if any) / 0 - 40
// / / bytes
// | | |
// | | v
// +--------------------------------------------------------------+ ---
class ipv4_header
{
public:
ipv4_header() { std::fill(rep_, rep_ + sizeof(rep_), 0); }
unsigned char version() const { return (rep_[0] >> 4) & 0xF; }
unsigned short header_length() const { return (rep_[0] & 0xF) * 4; }
unsigned char type_of_service() const { return rep_[1]; }
unsigned short total_length() const { return decode(2, 3); }
unsigned short identification() const { return decode(4, 5); }
bool dont_fragment() const { return (rep_[6] & 0x40) != 0; }
bool more_fragments() const { return (rep_[6] & 0x20) != 0; }
unsigned short fragment_offset() const { return decode(6, 7) & 0x1FFF; }
unsigned int time_to_live() const { return rep_[8]; }
unsigned char protocol() const { return rep_[9]; }
unsigned short header_checksum() const { return decode(10, 11); }
boost::asio::ip::address_v4 source_address() const
{
boost::asio::ip::address_v4::bytes_type bytes
= { { rep_[12], rep_[13], rep_[14], rep_[15] } };//ip地址怎么构造
return boost::asio::ip::address_v4(bytes);
}
boost::asio::ip::address_v4 destination_address() const
{
boost::asio::ip::address_v4::bytes_type bytes
= { { rep_[16], rep_[17], rep_[18], rep_[19] } };
return boost::asio::ip::address_v4(bytes);
}
friend std::istream& operator>>(std::istream& is, ipv4_header& header)
{
is.read(reinterpret_cast(header.rep_), 20);
if (header.version() != 4)
is.setstate(std::ios::failbit);// iostream.setstate 不太懂
std::streamsize options_length = header.header_length() - 20;
if (options_length < 0 || options_length > 40)
is.setstate(std::ios::failbit);
else
is.read(reinterpret_cast(header.rep_) + 20, options_length);
return is;
}
private:
unsigned short decode(int a, int b) const
{ return (rep_[a] << 8) + rep_[b]; }
unsigned char rep_[60];
};
#endif // IPV4_HEADER_HPP 3. main.cpp
//
// ping.cpp
// ~~~~~~~~
//
// Copyright (c) 2003-2013 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)
//
#include
#include
#include
#include
#include
#include "icmp_header.h"
#include "ipv4_header.h"
using boost::asio::ip::icmp;
using boost::asio::deadline_timer;
namespace posix_time = boost::posix_time;
class pinger
{
public:
pinger(boost::asio::io_service& io_service, const char* destination)
: resolver_(io_service), socket_(io_service, icmp::v4()),
timer_(io_service), sequence_number_(0), num_replies_(0)
{
icmp::resolver::query query(icmp::v4(), destination, "");
destination_ = *resolver_.resolve(query);//目标地址
start_send();
start_receive();
}
private:
void start_send()
{
std::string body("\"Hello!\" from Asio ping.");
// Create an ICMP header for an echo request.
icmp_header echo_request;
echo_request.type(icmp_header::echo_request);
echo_request.code(0);
echo_request.identifier(get_identifier());
echo_request.sequence_number(++sequence_number_);
compute_checksum(echo_request, body.begin(), body.end());
// Encode the request packet.
boost::asio::streambuf request_buffer;
std::ostream os(&request_buffer);
os << echo_request << body;
// Send the request.
time_sent_ = posix_time::microsec_clock::universal_time();//boost 得到时间
socket_.send_to(request_buffer.data(), destination_);
// Wait up to five seconds for a reply.
num_replies_ = 0;
timer_.expires_at(time_sent_ + posix_time::seconds(5));
timer_.async_wait(boost::bind(&pinger::handle_timeout, this));
}
void handle_timeout()
{
if (num_replies_ == 0)
std::cout << "Request timed out" << std::endl;
// Requests must be sent no less than one second apart.
timer_.expires_at(time_sent_ + posix_time::seconds(1));
timer_.async_wait(boost::bind(&pinger::start_send, this));
}
void start_receive()
{
// Discard any data already in the buffer.
reply_buffer_.consume(reply_buffer_.size());//streambuf.comsume()清空
// Wait for a reply. We prepare the buffer to receive up to 64KB.
socket_.async_receive(reply_buffer_.prepare(65536),//准备缓冲区
boost::bind(&pinger::handle_receive, this, _2));
}
void handle_receive(std::size_t length)
{
// The actual number of bytes received is committed to the buffer so that we
// can extract it using a std::istream object.
reply_buffer_.commit(length);//转移到streambuf中，
// Decode the reply packet.
std::istream is(&reply_buffer_);
ipv4_header ipv4_hdr;
icmp_header icmp_hdr;
is >> ipv4_hdr >> icmp_hdr;
// We can receive all ICMP packets received by the host, so we need to
// filter out only the echo replies that match the our identifier and
// expected sequence number.
if (is && icmp_hdr.type() == icmp_header::echo_reply
&& icmp_hdr.identifier() == get_identifier()
&& icmp_hdr.sequence_number() == sequence_number_)
{
// If this is the first reply, interrupt the five second timeout.
if (num_replies_++ == 0)
timer_.cancel();
// Print out some information about the reply packet.
posix_time::ptime now = posix_time::microsec_clock::universal_time();
std::cout << length - ipv4_hdr.header_length()
<< " bytes from " << ipv4_hdr.source_address()
<< ": icmp_seq=" << icmp_hdr.sequence_number()
<< ", ttl=" << ipv4_hdr.time_to_live()
<< ", time=" << (now - time_sent_).total_milliseconds() << " ms"
<< std::endl;
}
start_receive();
}
static unsigned short get_identifier()
{
#if defined(BOOST_ASIO_WINDOWS)
return static_cast(::GetCurrentProcessId());//全局函数，widows api，得到进程id
#else
return static_cast(::getpid());//linux
#endif
}
icmp::resolver resolver_;
icmp::endpoint destination_;
icmp::socket socket_;
deadline_timer timer_;
unsigned short sequence_number_;
posix_time::ptime time_sent_;
boost::asio::streambuf reply_buffer_;
std::size_t num_replies_;
};
int main(int argc, char* argv[])
{
try
{
if (argc != 2)
{
std::cerr << "Usage: ping " << std::endl;
#if !defined(BOOST_ASIO_WINDOWS)
std::cerr << "(You may need to run this program as root.)" << std::endl;
#endif
return 1;
}
boost::asio::io_service io_service;
pinger p(io_service, argv[1]);
io_service.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << std::endl;
}
}