c++ socket read()有时在连接到服务器时返回-1

Question

我是 c++ 的新手，我正在进行套接字编程，同时从服务器向客户端发送数据，read() 函数有时会返回 -1，有时会返回 64，并且工作正常。我在下面附上了我的代码，请给我一个更好的解决方案。

服务器.cpp

  if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
{
    logger("socket failed");
    exit(EXIT_FAILURE);
}

// Forcefully attaching socket to the port 8080
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT,
                                              &opt, sizeof(opt)))
{
    logger("setsockopt");
    exit(EXIT_FAILURE);
}
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_addr.s_addr = inet_addr("192.168.0.4");
address.sin_port = htons( PORT );


// Forcefully attaching socket to the port 8080
if (bind(server_fd, (struct sockaddr *)&address,
                             sizeof(address))<0)
{
    logger("bind failed");
    exit(EXIT_FAILURE);
}
if (listen(server_fd, 3) < 0)
{
    logger("listen");
    exit(EXIT_FAILURE);
}

 while (true)
 {
                    if ((new_socket = accept(server_fd, (struct sockaddr *)&address,
                                       (socklen_t*)&addrlen))<0)
                    {
                            logger("socket not accept");
                            exit(EXIT_FAILURE);
                    }
                    //valread = read( new_socket , buffer, 1024);
                    //printf("%s\n",buffer );
                    send(new_socket , hash_key , strlen(hash_key) , 0 );
                    //printf("Hello message sent\n");
   }
return 0;

客户端.cpp

                 arg |= O_NONBLOCK;
                  if( fcntl(sock, F_SETFL, arg) < 0) {
                     fprintf(stderr, "Error fcntl(..., F_SETFL) (%s)\n", strerror(errno));
                     exit(0);
                  }
                   int res;
                   res = connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
                  if (res < 0) {
                     if (errno == EINPROGRESS) {
                        fprintf(stderr, "EINPROGRESS in connect() - selecting\n");
                        do {
                           tv.tv_sec = 50;
                           tv.tv_usec = 0;
                           FD_ZERO(&myset);
                           FD_SET(sock, &myset);
                           res = select(sock+1, NULL, &myset, NULL, &tv);
                           if (res < 0 && errno != EINTR) {
                              fprintf(stderr, "Error connecting %d - %s\n", errno, strerror(errno));
                              exit(0);
                           }
                           else if (res > 0) {
                              // Socket selected for write
                              lon = sizeof(int);
                              if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)(&valopt), &lon) < 0) {
                                 fprintf(stderr, "Error in getsockopt() %d - %s\n", errno, strerror(errno));
                                 exit(0);
                              }
                              // Check the value returned...
                              if (valopt) {
                                 fprintf(stderr, "Error in delayed connection() %d - %s\n", valopt, strerror(valopt)
                );
                                 exit(0);
                              }
                              break;
                           }
                           else {
                              fprintf(stderr, "Timeout in select() - Cancelling!\n");
                              exit(0);
                           }
                        } while (1);
                     }
                     else {
                        fprintf(stderr, "Error connecting %d - %s\n", errno, strerror(errno));
                        exit(0);
                     }
                     valread = read( sock , buffer, 1024);
                    cout<<valread<<endl;

Answer 1

您监听来自客户端的传入连接，并在服务器端的同一循环中将数据发送到客户端。您应该使用线程将它们分开。您的服务器代码在接受例程中阻塞。