3
所以我正在浏览asio教程,我编译了同步的白天客户端和同步的白天服务器。我正在玩弄服务器端的代码,通过改变端口(在站点的代码中,他们硬编码为13端口),通过命令行传入。boost-asio如何知道服务器在哪个端口上运行?
我注意到客户端只能在服务器在端口13上运行时连接,但有趣的是客户端上没有任何东西说服务器在端口上。
任何人都可以向我解释这个程序如何知道服务器运行的端口以及为什么它只能用于端口13?下面是服务器http://www.boost.org/doc/libs/1_45_0/doc/html/boost_asio/tutorial/tutdaytime2/src.html
//
// client.cpp
// ~~~~~~~~~~
//
// Copyright (c) 2003-2010 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 <iostream>
#include <boost/array.hpp>
#include <boost/asio.hpp>
using boost::asio::ip::tcp;
int main(int argc, char* argv[])
{
try
{
if (argc != 2)
{
std::cerr << "Usage: client <host>" << std::endl;
return 1;
}
boost::asio::io_service io_service;
tcp::resolver resolver(io_service);
tcp::resolver::query query(argv[1], "daytime");
tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
tcp::resolver::iterator end;
tcp::socket socket(io_service);
boost::system::error_code error = boost::asio::error::host_not_found;
while (error && endpoint_iterator != end)
{
socket.close();
socket.connect(*endpoint_iterator++, error);
}
if (error)
throw boost::system::system_error(error);
for (;;)
{
boost::array<char, 128> buf;
boost::system::error_code error;
size_t len = socket.read_some(boost::asio::buffer(buf), error);
if (error == boost::asio::error::eof)
break; // Connection closed cleanly by peer.
else if (error)
throw boost::system::system_error(error); // Some other error.
std::cout.write(buf.data(), len);
}
}
catch (std::exception& e)
{
std::cerr << e.what() << std::endl;
}
return 0;
}
所以如果你用“echo”或“http”替换“daytime”,它会查找通常与echo或http服务器相关的端口? – ThatQuestionGuy 2011-02-13 00:26:31