Boost ASIO异步接收器不打开侦听端口

Boost ASIO async acceptor not opening a listening port

本文关键字:ASIO 异步 接收器 Boost      更新时间:2023-10-16

操作系统:linux 64位ARCH.

BOOST: 1.46.1

编译器:clang++/GCC.

我有一个代码片段,其中有一个tcp接受器在boost::asio示例(聊天服务器)上建模。然而,当我运行片段时,没有侦听TCP套接字显示在netstat侦听(linux)中。但是,在编译时,聊天服务器示例确实会显示出来。有人能指出我做错了什么吗?

#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/bind.hpp>
#include <list>
#include <iostream>

using namespace boost::asio;
  using namespace boost::asio::ip;
  class ClientConnection
  {
  public:
    ClientConnection(io_service & io_s)
      : m_socket(io_s) {}
    tcp::socket & socket() { return m_socket; }
  private:
    tcp::socket m_socket;  
  };
  typedef boost::shared_ptr<ClientConnection> client_connection_ptr;
  class ClientConnectionAcceptor
  {
  public:
    ClientConnectionAcceptor(unsigned short port)
      : m_io_service(),
        m_port(port),
        m_endpoint(tcp::v4(), m_port),
        m_acceptor(m_io_service, m_endpoint)
    {
      std::cout << "acceptor is open : " << m_acceptor.is_open() << std::endl;
      client_connection_ptr ccp(new ClientConnection(m_io_service));
      m_acceptor.async_accept(  
        ccp->socket(),
        boost::bind(&ClientConnectionAcceptor::handle_accept,this, 
        ccp, placeholders::error));
    } 
    void handle_accept(client_connection_ptr ccp, const boost::system::error_code & error)
    {
      std::cout << "in handle_accept" << std::endl;  
      if(!error)
      {
       // m_rpc_oracle.AddNewClient(ccp);
        client_connection_ptr new_ccp(new ClientConnection(m_io_service));
        m_acceptor.async_accept(  
          new_ccp->socket(),
          boost::bind(&ClientConnectionAcceptor::handle_accept,this, 
          ccp, placeholders::error));
      }
    }
    io_service & io_service() { return m_io_service; }
  private:
    boost::asio::io_service m_io_service;
    tcp::endpoint m_endpoint;
    tcp::acceptor m_acceptor;
    unsigned short m_port;
  };

int main()
{
  ClientConnectionAcceptor acceptor(5000);
  acceptor.io_service().run();
}    

我发现如果我将endpointacceptor更改为共享指针,我可以在我的Windows机器上工作,而不是通过将它们作为参数传递给构造函数来创建它们,我专门在构造函数中创建共享指针。我不太确定为什么会这样。我唯一的猜测是,也许没有保证构造函数参数是按照它们出现的顺序传递或创建的,因此您可以尝试使用尚未正确初始化的endpoint创建acceptor ?这是我唯一的猜测。如果这对你有用,请告诉我。我可以通过5000端口的localhost成功连接。

如果没有这些更改,我试图通过localhost连接的客户端告诉我连接被主动拒绝。这种安排是成功的,但是,似乎偏离您的原始代码尽可能少。希望能有所帮助。

#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/bind.hpp>
#include <list>
#include <iostream>
using namespace boost::asio;
using namespace boost::asio::ip;
class ClientConnection
{
public:
  ClientConnection(io_service & io_s)
    : m_socket(io_s) {}
  tcp::socket & socket() { return m_socket; }
private:
  tcp::socket m_socket;  
};
typedef boost::shared_ptr<ClientConnection> client_connection_ptr;
class ClientConnectionAcceptor
{
public:
  ClientConnectionAcceptor(unsigned short port)
    : m_io_service(),
    m_port(port)
  {
    // now initializing endpoint and acceptor as shared pointers inside the constructor
    m_endpoint = boost::shared_ptr<tcp::endpoint>(new tcp::endpoint(tcp::v4(), m_port));
    m_acceptor = boost::shared_ptr<tcp::acceptor>(new tcp::acceptor(m_io_service, *m_endpoint));
    std::cout << "acceptor is open : " << m_acceptor->is_open() << std::endl;
    client_connection_ptr ccp(new ClientConnection(m_io_service));
    m_acceptor->async_accept(  
      ccp->socket(),
      boost::bind(&ClientConnectionAcceptor::handle_accept,this, 
      ccp, placeholders::error));
  } 
  void handle_accept(client_connection_ptr ccp, const boost::system::error_code & error)
  {
    std::cout << "in handle_accept" << std::endl;  
    if(!error)
    {
      // m_rpc_oracle.AddNewClient(ccp);
      client_connection_ptr new_ccp(new ClientConnection(m_io_service));
      m_acceptor->async_accept(  
        new_ccp->socket(),
        boost::bind(&ClientConnectionAcceptor::handle_accept,this, 
        ccp, placeholders::error));
    }
  }
  io_service & io_service() { return m_io_service; }
private:
  boost::asio::io_service m_io_service;
  boost::shared_ptr<tcp::endpoint> m_endpoint;
  boost::shared_ptr<tcp::acceptor> m_acceptor;
  unsigned short m_port;
};

int main()
{
  ClientConnectionAcceptor acceptor(5000);
  acceptor.io_service().run();
}    

编辑

经过进一步的调查,发现这个问题实际上与ClientConnectionAcceptor类的初始化列表有关。在类定义中,成员m_portm_endpointm_acceptor之后声明为。因此,尽管初始化列表在 endpointacceptor创建之前设置了端口号,但实际上,直到之后的已经创建了endpointacceptor,端口值才有效或初始化。修改类定义,使成员m_portendpointacceptor之前声明,可以解决这个问题。

在编译代码时出现错误

async_accept.cc:56: error: declaration of ‘boost::asio::io_service& ClientConnectionAcceptor::io_service()’
/opt/local/include/boost/asio/io_service.hpp:186: error: changes meaning of ‘io_service’ from ‘class boost::asio::io_service’

改变
io_service & io_service() { return m_io_service; }

io_service & get_io_service() { return m_io_service; }

似乎解决了编译失败。运行生成的二进制文件为我显示了netstat -l -t中的侦听套接字。