-客户端-服务器应用程序-服务器端的recv()可以正常工作，但客户端的recv()会阻塞程序

我正在编写客户机-服务器应用程序。到目前为止一切正常，客户端发送请求，服务器接收，解析。但是现在我想发送回一个答案，所以我复制了这两个函数，我把write()从客户机放到服务器上，把read()从服务器放到客户机上。
当我运行程序的时候，现在一切都阻塞了，服务器等待，客户端也等待。当我按ctrl+c客户机时，服务器解除阻塞并解析正确的请求并等待另一个请求。请问出什么事了?

来自客户端的部分代码:

  params.port = atoi(params.pvalue.c_str());  
  hostent *host;              
  sockaddr_in socketHelper;    
  int clientSocket;           
  char buf[BUFFER_LEN];     
  int size;                   
  string data;                
  string recieved;
  // gets info about server
  host = gethostbyname(params.hvalue.c_str());
  if(host == NULL) {
    printErr(ERR_HOSTNAME);
    return ERR_HOSTNAME;
  }
  // makes a socket
  if((clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
    printErr(ERR_SOCKET);
    return ERR_SOCKET;
  }
  socketHelper.sin_family = AF_INET;
  socketHelper.sin_port = htons(params.port);
  memcpy(&(socketHelper.sin_addr), host->h_addr, host->h_length);
  // connects the socket
  if(connect(clientSocket, (sockaddr *)&socketHelper, sizeof(socketHelper)) == -1) {
    printErr(ERR_CONNECTION);
    return ERR_CONNECTION;
  }
  // sends data
  if((size = write(clientSocket, request.c_str(), request.length())) == -1) {
    printErr(ERR_SEND);
    return ERR_SEND;
  } 
  // recieves data
  while ((size = read(clientSocket, buf, BUFFER_LEN)) != 0) {
    recieved.erase();
    recieved.append(buf, size);
    data = data + recieved;
  }
  // closes a connection
  close(clientSocket);

和部分来自服务器的代码:

while(1) {
    int clientSocket = accept(GodParticle, (struct sockaddr*) &GodAddr, &clientSocketSize);
    if(clientSocket == -1) {
      printErr(ERR_ACCEPT);
      return ERR_ACCEPT;
    }
    if((pid = fork()) == 0) {
      while ((size = read(clientSocket, buf, BUFFER_LEN)) != 0) {
        recieved.erase();
        recieved.append(buf, size);
        request = request + recieved;
      }
      parserInput(request);
      getData();
      parserOutput();
      if((size = write(clientSocket, sendback.c_str(), sendback.length())) == -1) {
        printErr(ERR_SEND);
        return ERR_SEND;
      } 
      close(clientSocket);
      exit(ERR_OK);
    }
  }