服务器套接字只能连接几次（Winsock C++）

Posted 2023-02-21

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【中文标题】服务器套接字只能连接几次（Winsock C++）【英文标题】：Server socket can connect few times only (Winsock C++) 【发布时间】：2013-03-13 03:07:53 【问题描述】：

您好，我正在尝试用 C++ 编写服务器 winsock 以允许从 php 客户端代码进行连接。 PHP将从服务器请求数据，接收然后关闭连接。但是，2-3次连接后，再次请求PHP时，在socket_read()处挂起，页面一直在加载，服务器没有收到FD_ACCEPT事件。是因为 TIME_WAIT 连接还没有关闭吗？任何关于代码改进的建议也会很好。

SOCKET s;
SOCKADDR_IN from;
int fromLen = sizeof(from);
int port = 1111;

int listenOnPort(int portNo)

    WSAData w;

    int error = WSAStartup(0x0202, &w); // fill in wsa info

    if(error)
    
        printError(5);
        return 0;
    

    if(w.wVersion !=  0x0202)
    
        printError(6);
        WSACleanup();
        return 0;
    

    SOCKADDR_IN addr;
    SOCKET client;

    addr.sin_family = AF_INET;
    addr.sin_port = htons(portNo);
    addr.sin_addr.s_addr = htonl(INADDR_ANY);

    s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if(s == INVALID_SOCKET)
    
        printError(7);
        return 0;
    

    BOOL bOptVal = TRUE;
    int bOptLen = sizeof (BOOL);
    if(setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&bOptVal, bOptLen) == SOCKET_ERROR)
    
        printError(12);
        return 0;
    

    if(bind(s, (LPSOCKADDR)&addr, sizeof(addr)) == SOCKET_ERROR)
    
        printError(8);
        return 0;
    

    if( listen(s, 1) == SOCKET_ERROR ) //start listening
    
        printError(13);
        return 0;
    

    //WSAAsyncSelect(s, hwnd, 1045, FD_READ | FD_CONNECT | FD_CLOSE | FD_ACCEPT);

    cout << "Ready to accept connection, listening on port " << portNo << endl;

    CreateThread(0,0, &listenForEvents, NULL, 0, 0);

    //listenForEvents();

    return 1; //ok


DWORD WINAPI listenForEvents(void* lp)

    HANDLE sockEv=CreateEvent(NULL,TRUE,FALSE,NULL);
    if(WSAEventSelect(s,sockEv,FD_ACCEPT|FD_CONNECT| FD_READ | FD_CLOSE )==SOCKET_ERROR) 
        printError(9);

    for(;;) 
      if(WSAWaitForMultipleEvents(1,&sockEv,FALSE,INFINITE,FALSE)!=WSA_WAIT_EVENT_0)
          printError(10);

      WSANETWORKEVENTS wsaEvents=0;
      if(WSAEnumNetworkEvents(s,sockEv,&wsaEvents)==SOCKET_ERROR)
          printError(11);

      if((wsaEvents.lNetworkEvents & FD_ACCEPT)==FD_ACCEPT) 
           SOCKET tempSock = accept(s, (struct  sockaddr*) &from, &fromLen);
            s = tempSock; //switch our old socket to the new one

            char acceptAddr[100];
            char* msg = "Connnection from [%s] accepted.";
            //sprintf(acceptAddr, msg, inet_ntoa(from.sin_addr) );
            sprintf_s(acceptAddr, strlen(msg) + 100, msg, inet_ntoa(from.sin_addr));

            cout << acceptAddr << endl;
            hasClient = true;
      
      else if((wsaEvents.lNetworkEvents & FD_READ) == FD_READ)
          char buffer[1000];
          memset(buffer, 0, sizeof(buffer));
          recv(s, buffer, sizeof(buffer)-1, 0);

          receiveAction(string(buffer));

          //cout << buffer << endl;
      
        else if((wsaEvents.lNetworkEvents & FD_CLOSE) == FD_CLOSE)
            shutdown(s, SD_BOTH );
            closesocket(s);
            cout << "socket closed" << endl;
            startServer(); // start server again
            return 0;
        
      else if(wsaEvents.lNetworkEvents==0) 
          printError(14);
        cout << "lNetworkEvents==0" << endl;
      
    


void startServer()
    listenOnPort(port);

这是 PHP 代码。

/* Get the port for the WWW service. */
// $service_port = getservbyname('www', 'tcp');
$service_port = "1111";

/* Get the IP address for the target host. */
$address = "192.168.3.5";

/* Create a TCP/IP socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) 
    echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";
    die();
 else 
    //echo "OK.\n";


//echo "Attempting to connect to '$address' on port '$service_port'...";
$result = socket_connect($socket, $address, $service_port);
if ($result === false) 
    echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "\n";
    die();
 else 
    //echo "OK.\n";


$out = '';

//echo "Sending HTTP HEAD request...";
$result = socket_write($socket, $json, strlen($json));

if ($result === false) 
    echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "\n";
    die();
 else 
    //echo "OK.\n";



echo socket_read($socket, 2048);
// while ($out = socket_read($socket, 2048)) 
    // echo $out;
// 

socket_close($socket);

【问题讨论】：

【参考方案1】：

终于成功了，我对winsock函数、流程等不太了解。这是工作的。关键是让侦听器套接字保持活动状态，然后将客户端/接受的套接字存储在另一个地方。

SOCKET sock[2];
SOCKADDR_IN from;
int fromLen = sizeof(from);
int port = 1111;
int listenOnPort(int portNo)

    WSAData w;

    int error = WSAStartup(0x0202, &w); // fill in wsa info

    if(error)
    
        printError(5);
        return 0;
    

    if(w.wVersion !=  0x0202)
    
        printError(6);
        WSACleanup();
        return 0;
    

    SOCKADDR_IN addr;
    SOCKET client;

    addr.sin_family = AF_INET;
    addr.sin_port = htons(portNo);
    addr.sin_addr.s_addr = htonl(INADDR_ANY);

    sock[0] = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    if(sock[0] == INVALID_SOCKET)
    
        printError(7);
        return 0;
    

    BOOL bOptVal = TRUE;
    int bOptLen = sizeof (BOOL);
    if(setsockopt(sock[0], SOL_SOCKET, SO_REUSEADDR, (char *)&bOptVal, bOptLen) == SOCKET_ERROR)
    
        printError(12);
        return 0;
    

    if(bind(sock[0], (LPSOCKADDR)&addr, sizeof(addr)) == SOCKET_ERROR)
    
        printError(8);
        return 0;
    

    if( listen(sock[0], 1) == SOCKET_ERROR ) //start listening
    
        printError(13);
        return 0;
    

    //WSAAsyncSelect(sock[0], hwnd, 1045, FD_READ | FD_CONNECT | FD_CLOSE | FD_ACCEPT);

    cout << "Ready to accept connection, listening on port " << portNo << endl;

    CreateThread(0,0, &listenForEvents, NULL, 0, 0);

    //listenForEvents();

    return 1; //ok



DWORD WINAPI listenForEvents(void* lp)

    HANDLE sockEv[2];
    sockEv[0]=CreateEvent(NULL,TRUE,FALSE,NULL);
    sockEv[1]=CreateEvent(NULL,TRUE,FALSE,NULL);
    if(WSAEventSelect(sock[0],sockEv[0],FD_ACCEPT|FD_CONNECT|FD_CLOSE )==SOCKET_ERROR) 
        printError(9);

    for(;;) 

        int index = WSAWaitForMultipleEvents(2,sockEv,FALSE,INFINITE,FALSE);
        //if(index != WSA_WAIT_EVENT_0)
        //  printError(10);

        index -= WSA_WAIT_EVENT_0;

      WSANETWORKEVENTS wsaEvents=0;
      if(WSAEnumNetworkEvents(sock[index],sockEv[index],&wsaEvents)==SOCKET_ERROR)
          printError(11);

      if((wsaEvents.lNetworkEvents & FD_ACCEPT)==FD_ACCEPT) 
            sock[index+1]= accept(sock[index], (struct  sockaddr*) &from, &fromLen);
            //s = clientSock; //switch our old socket to the new one

            if(WSAEventSelect(sock[index+1], sockEv[index+1], FD_READ|FD_CLOSE  ) == SOCKET_ERROR)
            
                printError(15);
            

            char acceptAddr[100];
            char* msg = "Connnection from [%s] accepted.";
            //sprintf(acceptAddr, msg, inet_ntoa(from.sin_addr) );
            sprintf_s(acceptAddr, strlen(msg) + 100, msg, inet_ntoa(from.sin_addr));

            cout << acceptAddr << endl;
            hasClient = true;
      
      else if((wsaEvents.lNetworkEvents & FD_READ) == FD_READ)
          char buffer[1000];
          memset(buffer, 0, sizeof(buffer));
          recv(sock[index], buffer, sizeof(buffer)-1, 0);

          receiveAction(string(buffer));

      
        else if((wsaEvents.lNetworkEvents & FD_CLOSE) == FD_CLOSE)
            shutdown(sock[index], SD_BOTH );
            closesocket(sock[index]);
            if(getDebug())
            
                cout << "socket closed" << endl;
            
            //startServer(); // start server again
            //return 0;
        
      else if(wsaEvents.lNetworkEvents==0) 
          printError(14);
        cout << "lNetworkEvents==0" << endl;

【讨论】：

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