Function netconn_alloc

components/net/lwip/lwip-2.1.2/src/api/api_msg.c:704–785

* Create a new netconn (of a specific type) that has a callback function. * The corresponding pcb is NOT created! * * @param t the type of 'connection' to create (@see enum netconn_type) * @param callback a function to call on status changes (RX available, TX'ed) * @return a newly allocated struct netconn or * NULL on memory error */

 *         NULL on memory error
 */
struct netconn *
netconn_alloc(enum netconn_type t, netconn_callback callback)
{
  struct netconn *conn;
  int size;
  u8_t init_flags = 0;

  conn = (struct netconn *)memp_malloc(MEMP_NETCONN);
  if (conn == NULL) {
    return NULL;
  }

  conn->pending_err = ERR_OK;
  conn->type = t;
  conn->pcb.tcp = NULL;

  /* If all sizes are the same, every compiler should optimize this switch to nothing */
  switch (NETCONNTYPE_GROUP(t)) {
#if LWIP_RAW
    case NETCONN_RAW:
      size = DEFAULT_RAW_RECVMBOX_SIZE;
      break;
#endif /* LWIP_RAW */
#if LWIP_UDP
    case NETCONN_UDP:
      size = DEFAULT_UDP_RECVMBOX_SIZE;
#if LWIP_NETBUF_RECVINFO
      init_flags |= NETCONN_FLAG_PKTINFO;
#endif /* LWIP_NETBUF_RECVINFO */
      break;
#endif /* LWIP_UDP */
#if LWIP_TCP
    case NETCONN_TCP:
      size = DEFAULT_TCP_RECVMBOX_SIZE;
      break;
#endif /* LWIP_TCP */
    default:
      LWIP_ASSERT("netconn_alloc: undefined netconn_type", 0);
      goto free_and_return;
  }

  if (sys_mbox_new(&conn->recvmbox, size) != ERR_OK) {
    goto free_and_return;
  }
#if !LWIP_NETCONN_SEM_PER_THREAD
  if (sys_sem_new(&conn->op_completed, 0) != ERR_OK) {
    sys_mbox_free(&conn->recvmbox);
    goto free_and_return;
  }
#endif

#if LWIP_TCP
  sys_mbox_set_invalid(&conn->acceptmbox);
#endif
  conn->state        = NETCONN_NONE;
#if LWIP_SOCKET
  /* initialize socket to -1 since 0 is a valid socket */
  conn->socket       = -1;