static CURLcode pop3_statemach_act(struct connectdata *conn)
{
  CURLcode result;
  curl_socket_t sock = conn->sock[FIRSTSOCKET];
  struct SessionHandle *data=conn->data;
  int pop3code;
  struct pop3_conn *pop3c = &conn->proto.pop3c;
  struct pingpong *pp = &pop3c->pp;
  size_t nread = 0;

  if(pp->sendleft)
    return Curl_pp_flushsend(pp);

  /* we read a piece of response */
  result = Curl_pp_readresp(sock, pp, &pop3code, &nread);
  if(result)
    return result;

  if(pop3code) {
    /* we have now received a full POP3 server response */
    switch(pop3c->state) {
    case POP3_SERVERGREET:
      if(pop3code != 'O') {
        failf(data, "Got unexpected pop3-server response");
        return CURLE_FTP_WEIRD_SERVER_REPLY;
      }

      if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
        /* We don't have a SSL/TLS connection yet, but SSL is requested. Switch
           to TLS connection now */
        result = Curl_pp_sendf(&pop3c->pp, "STLS");
        state(conn, POP3_STARTTLS);
      }
      else
        result = pop3_state_user(conn);
      if(result)
        return result;
      break;

    case POP3_USER:
      result = pop3_state_user_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_PASS:
      result = pop3_state_pass_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_STARTTLS:
      result = pop3_state_starttls_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_RETR:
      result = pop3_state_retr_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_LIST:
      result = pop3_state_list_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_LIST_SINGLE:
      result = pop3_state_list_single_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_QUIT:
      /* fallthrough, just stop! */
    default:
      /* internal error */
      state(conn, POP3_STOP);
      break;
    }
  }
  return result;
}
static CURLcode pop3_statemach_act(struct connectdata *conn)
{
  CURLcode result;
  curl_socket_t sock = conn->sock[FIRSTSOCKET];
  struct SessionHandle *data=conn->data;
  int pop3code;
  struct pop3_conn *pop3c = &conn->proto.pop3c;
  struct pingpong *pp = &pop3c->pp;
  size_t nread = 0;

  if(pp->sendleft)
    return Curl_pp_flushsend(pp);

   
  result = Curl_pp_readresp(sock, pp, &pop3code, &nread);
  if(result)
    return result;

  if(pop3code) {
     
    switch(pop3c->state) {
    case POP3_SERVERGREET:
      if(pop3code != 'O') {
        failf(data, "Got unexpected pop3-server response");
        return CURLE_FTP_WEIRD_SERVER_REPLY;
      }

      if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
         
        result = Curl_pp_sendf(&pop3c->pp, "STLS");
        state(conn, POP3_STARTTLS);
      }
      else
        result = pop3_state_user(conn);
      if(result)
        return result;
      break;

    case POP3_USER:
      result = pop3_state_user_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_PASS:
      result = pop3_state_pass_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_STARTTLS:
      result = pop3_state_starttls_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_RETR:
      result = pop3_state_retr_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_LIST:
      result = pop3_state_list_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_LIST_SINGLE:
      result = pop3_state_list_single_resp(conn, pop3code, pop3c->state);
      break;

    case POP3_QUIT:
       
    default:
       
      state(conn, POP3_STOP);
      break;
    }
  }
  return result;
}