客户端在连接被服务器关闭之前在套接字上打印一半数据

Question

我有这种情况。我正在尝试使用 C 中的套接字来发送和接收数据。客户端发送一些字符串，服务器对其进行操作，然后将其发送回客户端。一切都很好，但有一个小问题是:客户端仅从服务器接收第一行，显示它然后停止，直到连接在超时后被服务器关闭。虽然服务器发送的字节数 = 客户端收到的字节数。一旦连接关闭，字符串的其余部分就会由客户端显示。

我想知道您的想法和可能的问题。如果您有任何问题，请告诉我。

使用的协议(protocol):TCP

服务器代码如下:

for (;;)
    {
            n=recv(s, buf, RBUFLEN-1, 0);
        if (n < 0)
        {
            printf("Read error\n");
            closesocket(s);
            printf("Socket %d closed\n", s);
            break;
        }
        else if (n==0)
        {
            printf("Connection closed by party on socket %d\n",s);
            closesocket(s);
            break;
        }
        else
        {
            printf("Received line from socket %03d : \n",s);
            printf("N bytes received: %d \n",n);
                     // DoSomeOperationsOnTheData() 
                 if(send(s, buffer, n, 0) != n)
            printf("Write error while replying\n");
        else
        {
            printf("Reply sent: %d bytes\n",n);
        }
    }

客户端代码:

do
   {
    memset(buffer,0x0,BUFFER_SIZE);    //  init line
        rc = read(sd, buffer, BUFFER_SIZE);
        printf("\nReceived bytes: %d", rc);
        if( rc > 0)
        {
            printf("%s",buffer);
            size +=rc;
        }
    }while(rc>0);

    printf("\n   Total recieved response bytes: %d\n",size);

    close(sd);

Answer 1

这个

do
{
  memset(buffer, 0, BUFFER_SIZE);    //  init line
  rc = read(sd, buffer, BUFFER_SIZE);
  printf("\nReceived bytes: %d", rc);
  if( rc > 0)
  {
    printf("%s",buffer);
    size +=rc;
  }
}while(rc>0);

应该是:

memset(buffer,0x0,BUFFER_SIZE);    //  init line
size_t size = 0;
size_t toread = BUFFER_SIZE;
do
{
  ssize_t rc = read(sd, buffer+size, toread);

  if (rc > 0)
  {
    printf("\nReceived bytes:%zd", rc);
    printf("%s", buffer);
    size += rc;
    toread -= rc;
  }
  else if (rc == 0)
  {
    printf("The server hung up.\");
    break;
  }
  else
  {
    perror("read() failed");
    break;
  }
} while (toread);

if (toread < BUFFERSIZE)
{
  printf("Warning: Read less bytes (%zu) then expected (%d).\n", toread, BUFFERSIZE);
}