我需要你的帮助，因为我必须用 C++ 制作两个控制台应用程序:一个客户端能够向服务器发送尽可能多的字符串(以便发送坐标)。我成功地制作了一个阻塞套接字，但是因为我必须在开发平台(3D VIA Virtools)中集成它之后在每个帧调用我的脚本，所以除了使用异步套接字之外我没有其他解决方案。

*我的问题是我只能发送一次字符串，并且在我不再收到 FD_WRITE 之后...*

这开始让我发疯所以任何帮助将不胜感激(我是编程的初学者)，在此先感谢所有对我的问题感到有点担心的人

这是我的代码，

服务器

#include <winsock2.h> 
#include <Windows.h> 
#include <conio.h> 

#pragma comment(lib, "ws2_32.lib") 

#define   SOCKET_ERRNO   WSAGetLastError() 
#define ADDRESS "127.0.0.1" 
#define PORT 1234 

static SOCKET ListenFirstFreePort() 
{ 
   struct sockaddr_in addr; 
   int len = sizeof(addr);    
   SOCKET hSocket; 

   // Create socket 
   hSocket = socket( PF_INET, SOCK_STREAM, 0 ); 
   if( hSocket == INVALID_SOCKET ) 
   { 
      printf( "socket() error %d\n", SOCKET_ERRNO ); 
      exit(1); 
   } 

   // Connexion setting for local connexion 
   addr.sin_family = AF_INET ; 
   addr.sin_addr.s_addr = inet_addr(ADDRESS); 
   addr.sin_port = htons (PORT); 

   // bind socket 
   if ( bind( hSocket, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR ) 
   { 
      printf( "bind() error %d\n", SOCKET_ERRNO ); 
      exit(1); 
   } 

   // listen 
   if ( listen( hSocket, 100) == SOCKET_ERROR ) 
   { 
      printf( "listen() error %d\n", SOCKET_ERRNO ); 
      exit(1); 
   } 

   return hSocket; 
} 



void main() 
{ 
   WSADATA stack_info; 
   SOCKET ahSocket[2]; 
   WSAEVENT ahEvents[2]; 
   DWORD dwEvent; 
   WSANETWORKEVENTS NetworkEvents; 
   int rc; 

   // Initialize Winsock 
   WSAStartup(MAKEWORD(2,0), &stack_info) ; 

   // Create events 
   ahEvents[0] = WSACreateEvent(); 
   ahEvents[1] = WSACreateEvent(); 


   // Create listening socket 
   ahSocket[0] = ListenFirstFreePort(); 
   rc = WSAEventSelect(ahSocket[0], ahEvents[0], FD_ACCEPT ); 
   if( rc == SOCKET_ERROR ) 
   { 
      printf( "WSAEventSelect() error %d\n", SOCKET_ERRNO ); 
      exit(1); 
   } 

   while (TRUE) 
   { 
      // Waiting for so;ething to happen 
      // Basically we'll firstly receive the connexion of the client socket 
      // and then we'll be notificated when there will be some data to read 

      // look for events 
      dwEvent = WSAWaitForMultipleEvents( 2, ahEvents, FALSE, WSA_INFINITE, FALSE); 

      switch (dwEvent) 
      { 
      case WSA_WAIT_FAILED: 
         printf("WSAEventSelect: %d\n", WSAGetLastError()); 
         break; 
      case WAIT_IO_COMPLETION: 
      case WSA_WAIT_TIMEOUT: 
         break; 

      default: 

         //if there is one dwEvent-WSA_WAIT_EVENT_0 has to be substracted so as to dwEvent correspond to the index of the concerned socket 
         dwEvent -= WSA_WAIT_EVENT_0; 

         // enumeration of the events on the socket[dwEvent] 
         if (SOCKET_ERROR == WSAEnumNetworkEvents(ahSocket[dwEvent], ahEvents[dwEvent], &NetworkEvents)) 
         { 
            printf("WSAEnumNetworkEvent: %d lNetworkEvent %X\n",  
               WSAGetLastError(), NetworkEvents.lNetworkEvents); 
            NetworkEvents.lNetworkEvents = 0; 
         } 
         else  
         { 

            if (FD_CLOSE   & NetworkEvents.lNetworkEvents) 
            { 

               printf( "FD_CLOSE ok (dwEvent=%d)\n", dwEvent ); 
               printf( "press a key to exit\n" ); 
               getch(); // require conio.h 

               WSACloseEvent( ahEvents[0] ); 
               WSACloseEvent( ahEvents[1] ); 
               exit(0); 
            } 
            if (FD_READ & NetworkEvents.lNetworkEvents) 
            { 
               char szBuffer[256]; int cbRecv; 

               // Only the second socket expect to receive data 
               printf( "FD_READ ok (dwEvent=%d)\n", dwEvent ); 

               // read data 
               cbRecv = recv( ahSocket[dwEvent], szBuffer, sizeof(szBuffer) - 1, 0 ); 
               if( cbRecv <= 0 ) 
               { 
                  printf( "recv() error %d\n", SOCKET_ERRNO ); 
                  exit(1); 
               } 

               // On ecrit ce paquet (On remet le 0 au cas ou le paquet 
               // ait ete coupe en 2 - je sais, ca n'arrivera jamais en local) 
               // we put the 0 in case it has been cut - unlikey to happen on local network 
               szBuffer[cbRecv] = 0; 

               // write data in console window 
               printf( "socket %d : '%s'\n", dwEvent, szBuffer ); 
            } 
         } 
         if (FD_ACCEPT & NetworkEvents.lNetworkEvents) 
         { 
            struct sockaddr_in addrAccept; 
            int lenAccept; 
            lenAccept = sizeof( addrAccept ); 

            // we should have dwEvent=0 
            printf( "accept ok (dwEvent=%d)\n", dwEvent ); 

            // we create another socket to accept the connexion with the client socket 
            ahSocket[1] = accept(ahSocket[dwEvent], (struct sockaddr *)&addrAccept, &lenAccept); 

            // we want to be informed on when we'll be able read data from it 
            rc = WSAEventSelect(ahSocket[1], ahEvents[1], FD_READ|FD_CLOSE  ); 
            if( rc == SOCKET_ERROR ) 
            { 
               printf( "WSAEventSelect() error %d\n", SOCKET_ERRNO ); 
               exit(1); 
            } 
         } 
      } 
   } 
} 

客户端

#include <winsock2.h> 
#include <conio.h> 
#include <time.h> 

#pragma comment(lib, "ws2_32.lib") 

#define   SOCKET_ERRNO   WSAGetLastError() 
#define ADDRESS "127.0.0.1" 
#define PORT 1234 

SOCKET ConnectToPort() 
{ 
   struct sockaddr_in addr; 
   SOCKET hSocket; 
   u_long arg; int err; 

   // Create socket 
   hSocket = socket( PF_INET, SOCK_STREAM, 0 ); 
   if( hSocket == INVALID_SOCKET ) 
   { 
      printf( "socket() error %d\n", SOCKET_ERRNO ); 
      exit(1); 
   } 

   // Connexion setting for local connexion 
   addr.sin_family = AF_INET ; 
   addr.sin_addr.s_addr = inet_addr(ADDRESS); 
   addr.sin_port = htons (PORT); 

   // Connect 
   if( connect( hSocket, (struct sockaddr *)&addr, sizeof(addr) ) == SOCKET_ERROR ) 
   { 
      // As we are in non-blocking mode we'll always have the error 
      // WSAEWOULDBLOCK whichis actually not one 
      if( SOCKET_ERRNO != WSAEWOULDBLOCK ) 
      { 
         printf( "connect() error (%d)\n", SOCKET_ERRNO ); 
         exit(1); 
      } 
   } 

   return hSocket; 
} 



void main() 
{ 
   int initClockTime; 
   WSADATA stack_info; 
   SOCKET ahSocket[1]; 
   WSAEVENT ahEvents[1]; 
   DWORD dwEvent; 
   WSANETWORKEVENTS NetworkEvents; 
   int rc; 

   // Initialize Winsock 
   WSAStartup(MAKEWORD(2,0), &stack_info) ; 

   // Create event 
   ahEvents[0] = WSACreateEvent(); 

   // Create and connect a socket on the server socket 
   ahSocket[0]= ConnectToPort(); 

   // not sure if I have to use or not 
   /*u_long arg = 1; 
   ioctlsocket( ahSocket[0] , FIONBIO, &arg );*/ 

   // the application wants to receive notification of a completed connection 
   rc = WSAEventSelect(ahSocket[0], ahEvents[0], FD_CONNECT  ); 
   if( rc == SOCKET_ERROR ) 
   { 
      printf( "WSAEventSelect() error %d\n", SOCKET_ERRNO ); 
      exit(1); 
   } 

   while (TRUE) 
   { 
      // look for events 
      dwEvent = WSAWaitForMultipleEvents( 1, ahEvents, FALSE, 1000, FALSE); 

      switch (dwEvent) 
      { 
      case WSA_WAIT_FAILED: 
         printf("WSAEventSelect: %d\n", WSAGetLastError()); 
         break; 
      case WAIT_IO_COMPLETION: 
      case WSA_WAIT_TIMEOUT: 
         break; 

      default: 

         printf("while\n"); 

         //if there is one dwEvent-WSA_WAIT_EVENT_0 has to be substracted so as to dwEvent correspond to the index of the concerned socket 
         dwEvent -= WSA_WAIT_EVENT_0; 

         // enumeration of the events on the socket[dwEvent] 
         if (SOCKET_ERROR == WSAEnumNetworkEvents(ahSocket[dwEvent], ahEvents[dwEvent], &NetworkEvents)) 
         { 
            printf("WSAEnumNetworkEvent: %d lNetworkEvent %X\n", WSAGetLastError(), NetworkEvents.lNetworkEvents); 
            NetworkEvents.lNetworkEvents = 0; 
         } 
         else  
         { 


            if (FD_CONNECT & NetworkEvents.lNetworkEvents) 
            { 
               //connexion is OK 
               printf( "FD_CONNECT ok (dwEvent=%d)\n", dwEvent ); 

               // now that we are connected we want to send data or be aware when the other socket is disconnected 
               rc = WSAEventSelect(ahSocket[dwEvent], ahEvents[dwEvent], FD_CLOSE | FD_WRITE ); 
               if( rc == SOCKET_ERROR ) 
               { 
                  printf( "WSAEventSelect() error %d\n", SOCKET_ERRNO ); 
                  exit(1); 
               } 
            } 
            if (FD_CLOSE   & NetworkEvents.lNetworkEvents) 
            { 
               printf( "FD_CLOSE ok (dwEvent=%d)\n", dwEvent ); 
               printf( "press a key to exit\n" ); 
               getch(); 

               WSACloseEvent( ahEvents[0] ); 
               exit(0); 
            } 

            if (FD_WRITE & NetworkEvents.lNetworkEvents) 
            { 
               char szBuffer[256]; int cbBuffer; 

               printf( "FD_WRITE ok (dwEvent=%d)\n", dwEvent ); 

               // create string and return the size 
               cbBuffer = sprintf( szBuffer, "Coucou", dwEvent ); 


               // send the string with 0 at the end 
               rc = send( ahSocket[dwEvent], szBuffer, cbBuffer + 1, 0 ); 
               if (SOCKET_ERROR ==  rc) 
               { 
                  printf("WSAEnumNetworkEvent: %d lNetworkEvent %X\n",  WSAGetLastError(), NetworkEvents.lNetworkEvents); 
               } 

               // not sure if I have to use it 
               //WSAResetEvent(ahEvents[0]); 

            } 

         } 
      } 
   } 
} 

下载.cpp 文件:https://www.dropbox.com/s/pjuipz7v4iwr5ea/Clientserver%20TCP.zip

最佳答案

在第一个通知之后您没有收到 FD_WRITE 通知，因为您没有考虑 the documentation 中的以下段落:

The FD_WRITE network event is handled slightly differently. An FD_WRITE network event is recorded when a socket is first connected with a call to the connect, ConnectEx, WSAConnect, WSAConnectByList, or WSAConnectByName function or when a socket is accepted with accept, AcceptEx, or WSAAccept function and then after a send fails with WSAEWOULDBLOCK and buffer space becomes available. Therefore, an application can assume that sends are possible starting from the first FD_WRITE network event setting and lasting until a send returns WSAEWOULDBLOCK. After such a failure the application will find out that sends are again possible when an FD_WRITE network event is recorded and the associated event object is set.

在您第一次调用 send() 后，套接字仍然是可写的，因为它的出站缓冲区没有满。只要您仍有数据要发送，请继续调用 send() 直到它报告 WSAWOULDBLOCK 错误，指示缓冲区已满。那时，您必须跟踪剩余数据，直到收到指示套接字再次可写的 FD_WRITE 通知，以便您可以从中断处继续发送剩余数据。

关于c++ - 服务器/客户端 TCP 异步(winsock)//FD_WRITE 问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12205393/