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net/tcp/tcp_netpoll.c

+/****************************************************************************
+ * net/tcp/tcp_netpoll.c
+ *
+ *   Copyright (C) 2008-2009, 2011-2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <poll.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/net/net.h>
+
+#include <devif/devif.h>
+#include <socket/socket.h>
+#include "tcp/tcp.h"
+
+#ifdef HAVE_TCP_POLL
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+/* This is an allocated container that holds the poll-related information */
+
+struct tcp_poll_s
+{
+  FAR struct socket *psock;        /* Needed to handle loss of connection */
+  struct pollfd *fds;              /* Needed to handle poll events */
+  FAR struct devif_callback_s *cb; /* Needed to teardown the poll */
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: tcp_poll_interrupt
+ *
+ * Description:
+ *   This function is called from the interrupt level to perform the actual
+ *   TCP receive operation via by the device interface layer.
+ *
+ * Parameters:
+ *   dev      The structure of the network driver that caused the interrupt
+ *   conn     The connection structure associated with the socket
+ *   flags    Set of events describing why the callback was invoked
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Running at the interrupt level
+ *
+ ****************************************************************************/
+
+static uint16_t tcp_poll_interrupt(FAR struct net_driver_s *dev, FAR void *conn,
+                                   FAR void *pvpriv, uint16_t flags)
+{
+  FAR struct tcp_poll_s *info = (FAR struct tcp_poll_s *)pvpriv;
+
+  nllvdbg("flags: %04x\n", flags);
+
+  DEBUGASSERT(!info || (info->psock && info->fds));
+
+  /* 'priv' might be null in some race conditions (?) */
+
+  if (info)
+    {
+      pollevent_t eventset = 0;
+
+      /* Check for data or connection availability events. */
+
+      if ((flags & (TCP_NEWDATA | TCP_BACKLOG)) != 0)
+        {
+          eventset |= POLLIN & info->fds->events;
+        }
+
+      /* A poll is a sign that we are free to send data. */
+
+      if ((flags & TCP_POLL) != 0)
+        {
+          eventset |= (POLLOUT & info->fds->events);
+        }
+
+      /* Check for a loss of connection events. */
+
+      if ((flags & (TCP_CLOSE | TCP_ABORT | TCP_TIMEDOUT)) != 0)
+        {
+          /* Marki that the connection has been lost */
+
+          net_lostconnection(info->psock, flags);
+          eventset |= (POLLERR | POLLHUP);
+        }
+
+      /* Awaken the caller of poll() is requested event occurred. */
+
+      if (eventset)
+        {
+          info->fds->revents |= eventset;
+          sem_post(info->fds->sem);
+        }
+    }
+
+  return flags;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: tcp_pollsetup
+ *
+ * Description:
+ *   Setup to monitor events on one TCP/IP socket
+ *
+ * Input Parameters:
+ *   psock - The TCP/IP socket of interest
+ *   fds   - The structure describing the events to be monitored, OR NULL if
+ *           this is a request to stop monitoring events.
+ *
+ * Returned Value:
+ *  0: Success; Negated errno on failure
+ *
+ ****************************************************************************/
+
+int tcp_pollsetup(FAR struct socket *psock, FAR struct pollfd *fds)
+{
+  FAR struct tcp_conn_s *conn = psock->s_conn;
+  FAR struct tcp_poll_s *info;
+  FAR struct devif_callback_s *cb;
+  net_lock_t flags;
+  int ret;
+
+  /* Sanity check */
+
+#ifdef CONFIG_DEBUG
+  if (!conn || !fds)
+    {
+      return -EINVAL;
+    }
+#endif
+
+  /* Allocate a container to hold the poll information */
+
+  info = (FAR struct tcp_poll_s *)kmm_malloc(sizeof(struct tcp_poll_s));
+  if (!info)
+    {
+      return -ENOMEM;
+    }
+
+  /* Some of the  following must be atomic */
+
+  flags = net_lock();
+
+  /* Allocate a TCP/IP callback structure */
+
+  cb = tcp_callback_alloc(conn);
+  if (!cb)
+    {
+      ret = -EBUSY;
+      goto errout_with_lock;
+    }
+
+  /* Initialize the poll info container */
+
+  info->psock  = psock;
+  info->fds    = fds;
+  info->cb     = cb;
+
+  /* Initialize the callback structure.  Save the reference to the info
+   * structure as callback private data so that it will be available during
+   * callback processing.
+   */
+
+  cb->flags    = (TCP_NEWDATA | TCP_BACKLOG | TCP_POLL | TCP_CLOSE |
+                  TCP_ABORT | TCP_TIMEDOUT);
+  cb->priv     = (FAR void *)info;
+  cb->event    = tcp_poll_interrupt;
+
+  /* Save the reference in the poll info structure as fds private as well
+   * for use durring poll teardown as well.
+   */
+
+  fds->priv    = (FAR void *)info;
+
+#ifdef CONFIG_NET_TCPBACKLOG
+  /* Check for read data or backlogged connection availability now */
+
+  if (!IOB_QEMPTY(&conn->readahead) || tcp_backlogavailable(conn))
+#else
+  /* Check for read data availability now */
+
+  if (!IOB_QEMPTY(&conn->readahead))
+#endif
+    {
+      /* Normal data may be read without blocking. */
+
+      fds->revents |= (POLLRDNORM & fds->events);
+    }
+
+  /* Check for a loss of connection events.  We need to be careful here.
+   * There are four possibilities:
+   *
+   * 1) The socket is connected and we are waiting for data availability
+   *    events.
+   *
+   *    __SS_ISCONNECTED(f) == true
+   *    __SS_ISLISTENING(f) == false
+   *    __SS_ISCLOSED(f)    == false
+   *
+   *    Action: Wait for data availability events
+   *
+   * 2) This is a listener socket that was never connected and we are
+   *    waiting for connection events.
+   *
+   *    __SS_ISCONNECTED(f) == false
+   *    __SS_ISLISTENING(f) == true
+   *    __SS_ISCLOSED(f)    == false
+   *
+   *    Action: Wait for connection events
+   *
+   * 3) This socket was previously connected, but the peer has gracefully
+   *    closed the connection.
+   *
+   *    __SS_ISCONNECTED(f) == false
+   *    __SS_ISLISTENING(f) == false
+   *    __SS_ISCLOSED(f)    == true
+   *
+   *    Action: Return with POLLHUP|POLLERR events
+   *
+   * 4) This socket was previously connected, but we lost the connection
+   *    due to some exceptional event.
+   *
+   *    __SS_ISCONNECTED(f) == false
+   *    __SS_ISLISTENING(f) == false
+   *    __SS_ISCLOSED(f)    == false
+   *
+   *    Action: Return with POLLHUP|POLLERR events
+   */
+
+  if (!_SS_ISCONNECTED(psock->s_flags) && !_SS_ISLISTENING(psock->s_flags))
+    {
+      /* We were previously connected but lost the connection either due
+       * to a graceful shutdown by the remote peer or because of some
+       * exceptional event.
+       */
+
+      fds->revents |= (POLLERR | POLLHUP);
+    }
+
+  /* Check if any requested events are already in effect */
+
+  if (fds->revents != 0)
+    {
+      /* Yes.. then signal the poll logic */
+
+      sem_post(fds->sem);
+    }
+
+  net_unlock(flags);
+  return OK;
+
+errout_with_lock:
+  kmm_free(info);
+  net_unlock(flags);
+  return ret;
+}
+
+/****************************************************************************
+ * Function: tcp_pollteardown
+ *
+ * Description:
+ *   Teardown monitoring of events on an TCP/IP socket
+ *
+ * Input Parameters:
+ *   psock - The TCP/IP socket of interest
+ *   fds   - The structure describing the events to be monitored, OR NULL if
+ *           this is a request to stop monitoring events.
+ *
+ * Returned Value:
+ *  0: Success; Negated errno on failure
+ *
+ ****************************************************************************/
+
+int tcp_pollteardown(FAR struct socket *psock, FAR struct pollfd *fds)
+{
+  FAR struct tcp_conn_s *conn = psock->s_conn;
+  FAR struct tcp_poll_s *info;
+  net_lock_t flags;
+
+  /* Sanity check */
+
+#ifdef CONFIG_DEBUG
+  if (!conn || !fds->priv)
+    {
+      return -EINVAL;
+    }
+#endif
+
+  /* Recover the socket descriptor poll state info from the poll structure */
+
+  info = (FAR struct tcp_poll_s *)fds->priv;
+  DEBUGASSERT(info && info->fds && info->cb);
+  if (info)
+    {
+      /* Release the callback */
+
+      flags = net_lock();
+      tcp_callback_free(conn, info->cb);
+      net_unlock(flags);
+
+      /* Release the poll/select data slot */
+
+      info->fds->priv = NULL;
+
+      /* Then free the poll info container */
+
+      kmm_free(info);
+    }
+
+  return OK;
+}
+
+#endif /* HAVE_TCP_POLL */