Question

我有一个使用TCP连接进行通信的服务器 - 客户端程序。多个客户端可以同时连接到服务器。我想在这个系统上实现tcp打孔。

在客户端，它调用公共服务器查找我的服务器的公共IP端口。然后连接到它。

但是在服务器端，它必须打开一个端口连接到公共服务器，它还必须接受同一端口上的客户端连接请求。

我要做的是打开套接字并绑定到端口X，然后连接到公共服务器，然后将此套接字更改为侦听状态以接受传入连接一段时间，然后开始连接到公共服务器再次，一遍又一遍。

这是正确的方法吗？

编辑：我有另一个想法。它是打开一个新端口并连接到公共服务器。主服务器端口像往常一样正在侦听传入连接。当客户端想要连接时，公共服务器将通过新端口告诉我的服务器。它会阻止主端口监听传入连接，而是会连接到客户端进行打孔。然后它连接到公共服务器，它将服务器公共IP地址转发到客户端，然后像往常一样回去监听传入连接。然后，客户端将使用此地址连接到已打开TCP孔的服务器。

Answer 1

最好有两个套接字并维护服务器和客户端之间的连接。

m_nServerTCPSocket-用于连接和列表器套接字与服务器
m_nPeerPrivateTCPSocket-与同行（公共地址）连接
m_nPeerPublicTCPSocket-与对等方连接（私有地址，如果其他对等方位于同一网络中）
m_nListeningTCPSocket - 用于侦听同伴的套接字你需要接受来自peer的连接。

m_nConnectedPeerTCPSocket-＆GT;一旦你与其他同伴联系，你就会得到这个套接字。

while(end_client)    
{

   FD_ZERO(&fdRead);
   FD_ZERO(&fdWrite);
   FD_ZERO(&fdExcept);    

   if (pControlMgr->GetConnectionMgr()->GetListeningTCPSocket()>0)

   {

        FD_SET (pControlMgr->GetConnectionMgr()->GetListeningTCPSocket(),&fdRead);      
        FD_SET (pControlMgr->GetConnectionMgr()->GetListeningTCPSocket(),&fdExcept);
    }

    if (pControlMgr->GetConnectionMgr()->GetServerTCPSocket()>0)
    {

        FD_SET (pControlMgr->GetConnectionMgr()->GetServerTCPSocket(),&fdRead); 
        FD_SET (pControlMgr->GetConnectionMgr()->GetServerTCPSocket(),&fdExcept);
}
    if (pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket()>0)
{
    FD_SET (pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket(),&fdRead);      
    FD_SET (pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket(),&fdExcept);        
}

timeval tv;
tv.tv_sec = 2;
tv.tv_usec = 0;

nSelectRetVal =  select(NULL,&fdRead,NULL,&fdExcept,&tv);


if (nSelectRetVal>0)
{
    int nRecvRetVal = 0;
    /* TCP Server Socket handling */
    if ( FD_ISSET(pControlMgr->GetConnectionMgr()->GetServerTCPSocket(), &fdRead ))
    {           
        try
        {
            pRecvBuffer =  new char[TCP_RECV_SIZE];
            nRecvRetVal = recv(pControlMgr->GetConnectionMgr()->GetServerTCPSocket(),
                pRecvBuffer,TCP_RECV_SIZE,
                0);
            int n = WSAGetLastError();
            if (nRecvRetVal>0)
            {
                int nPeerNameRetVal = getpeername(pControlMgr->GetConnectionMgr()->GetServerTCPSocket(),(sockaddr*)&addrRemotePeer,&nSockAddrLen);
                if ( pControlMgr->HandlePacket(pRecvBuffer,addrRemotePeer)== -1 )                       
                {
                    if ( NULL != pRecvBuffer)
                    {
                        delete [] pRecvBuffer;
                        pRecvBuffer = NULL;
                        return 0 ;
                    }
                }
            }                           
        }           
        catch (...)
        {
            if ( NULL != pRecvBuffer )
            {
                delete [] pRecvBuffer;
                pRecvBuffer = NULL;
            }
        }

        if ( NULL != pRecvBuffer)
        {
            delete [] pRecvBuffer;
            pRecvBuffer = NULL;
        }       
    } /* TCP Server Socket handling */      

    int n;
    /* TCP Exception Server Socket handling */
    if ( FD_ISSET(pControlMgr->GetConnectionMgr()->GetServerTCPSocket(), &fdExcept ))
    {
        /*FD_CLR(pControlMgr->GetConnectionMgr().GetServerTCPSocket (),&fdRead);
        FD_CLR(pControlMgr->GetConnectionMgr().GetServerTCPSocket (),&fdExcept);*/
        n = WSAGetLastError();
        //return 0;
    }   
       if (FD_ISSET(pControlMgr->GetConnectionMgr()->GetListeningTCPSocket(),&fdRead))
    {
        sockaddr_in addrConnectedPeer;
        int nAddrLen =sizeof(addrConnectedPeer) ;
        int nConnectedSock = accept( pControlMgr->GetConnectionMgr()->GetListeningTCPSocket(),
            (sockaddr*)&addrConnectedPeer,
            &nAddrLen);
        int n1 = WSAGetLastError();
        if (nConnectedSock>0)
        {
            pControlMgr->GetConnectionMgr()->SetConnectedTCPSocket(nConnectedSock);
            int n = pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket();
            continue;
        }
    }
    /* TCP Exception Listening Socket handling */
    if ( FD_ISSET(pControlMgr->GetConnectionMgr()->GetListeningTCPSocket(), &fdExcept ))
    {
        FD_CLR(pControlMgr->GetConnectionMgr()->GetListeningTCPSocket (),&fdRead);
        FD_CLR(pControlMgr->GetConnectionMgr()->GetListeningTCPSocket (),&fdExcept);
        //return 0;
    }   /* TCP Exception Listening Socket handling */   

    /* Connected Peer TCP Read Socket handling */
    if ( FD_ISSET(pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket(), &fdRead ))
    {           
        try
        {
            pRecvBuffer =  new char[TCP_RECV_SIZE];
            nRecvRetVal = recv (pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket(),
                pRecvBuffer,TCP_RECV_SIZE,
                0);
            if (nRecvRetVal>0)
            {
                int nPeerNameRetVal = getpeername(pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket(),(sockaddr*)&addrRemotePeer,&nSockAddrLen);
                if ( pControlMgr->HandlePacket(pRecvBuffer,addrRemotePeer)== -1 )                       
                {
                    if ( NULL != pRecvBuffer)
                    {
                        delete [] pRecvBuffer;
                        pRecvBuffer = NULL;
                        return 0 ;
                    }
                }
            }                           
        }           
        catch (...)
        {
            if ( NULL != pRecvBuffer )
            {
                delete [] pRecvBuffer;
                pRecvBuffer = NULL;
            }
        }
        //FD_CLR(pControlMgr->GetConnectionMgr().GetConnectedTCPSocket(),&fdRead);  
        if ( NULL != pRecvBuffer)
        {
            delete [] pRecvBuffer;
            pRecvBuffer = NULL;
        }       
    } /* Peer TCP Read Socket handling */   
    /* TCP Exception Connected Socket handling */
    if ( FD_ISSET(pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket(), &fdExcept ))
    {
        /*FD_CLR(pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket (),&fdRead);
        FD_CLR(pControlMgr->GetConnectionMgr()->GetConnectedTCPSocket (),&fdExcept);
        return 0;*/
        n = WSAGetLastError();
    }

创建套接字的逻辑

      int CConnectionMgr::CreateSocket(const int nSockType)
      {
       //TODO: Add code here    
           if (InitWinSock() == -1) 
       {
        return -1;      
       }
       SetLocalIPAddress(); 

       m_nListeningTCPSocket = socket(AF_INET, SOCK_STREAM ,nSockType );                    
       if ( GetListeningTCPSocket() <0 )
        return -1;  
       if (BindSocket(GetListeningTCPSocket())<0)
        return -1;
       int nListenRet = listen(GetListeningTCPSocket(),SOMAXCONN);

        if (nListenRet!=0)
        {
        return -1;
         }      
         m_nPeerPrivateTCPSocket = socket(AF_INET, SOCK_STREAM ,nSockType );
         if (GetPeerPrivateTCPSocket()<0)
         return -1; 
        if (BindSocket(GetPeerPrivateTCPSocket())<0)
         return -1;

         m_nPeerPublicTCPSocket = socket(AF_INET, SOCK_STREAM ,nSockType );
         if ( GetPeerPublicTCPSocket()<0)
           return -1;
          if (BindSocket(GetPeerPublicTCPSocket())<0)
           return -1;

          m_nServerTCPSocket = socket(AF_INET, SOCK_STREAM ,nSockType );
          if (GetServerTCPSocket()<0)
           return -1;
          if (BindSocket(GetServerTCPSocket())<0)
           return -1;
        return 1;
         }

如何控制对等端口[TCP打孔]

1 个答案: