net: Implement shutdown() interface and tcp shutdown

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>

net/tcp/Make.defs

@@ -53,7 +53,7 @@ endif
 NET_CSRCS += tcp_conn.c tcp_seqno.c tcp_devpoll.c tcp_finddev.c tcp_timer.c
 NET_CSRCS += tcp_send.c tcp_input.c tcp_appsend.c tcp_listen.c tcp_close.c
 NET_CSRCS += tcp_monitor.c tcp_callback.c tcp_backlog.c tcp_ipselect.c
-NET_CSRCS += tcp_recvwindow.c tcp_netpoll.c tcp_ioctl.c
+NET_CSRCS += tcp_recvwindow.c tcp_netpoll.c tcp_ioctl.c tcp_shutdown.c
 
 # TCP write buffering
 

net/tcp/tcp.h

@@ -344,8 +344,9 @@ struct tcp_conn_s
   FAR struct devif_callback_s *connevents;
   FAR struct devif_callback_s *connevents_tail;
 
-  /* Reference to TCP close callback instance */
+  /* Reference to TCP shutdown/close callback instance */
 
+  FAR struct devif_callback_s *shdcb;
   FAR struct devif_callback_s *clscb;
   struct work_s                clswork;
 
@@ -767,6 +768,23 @@ void tcp_lost_connection(FAR struct tcp_conn_s *conn,
 
 int tcp_close(FAR struct socket *psock);
 
+/****************************************************************************
+ * Name: tcp_shutdown
+ *
+ * Description:
+ *   Gracefully shutdown a TCP connection by sending a SYN
+ *
+ * Input Parameters:
+ *   psock - An instance of the internal socket structure.
+ *   how   - Specifies the type of shutdown.
+ *
+ * Assumptions:
+ *   Called from normal user-level logic
+ *
+ ****************************************************************************/
+
+int tcp_shutdown(FAR struct socket *psock, int how);
+
 /****************************************************************************
  * Name: tcp_ipv4_select
  *

net/tcp/tcp_shutdown.c

@@ -0,0 +1,168 @@
+/****************************************************************************
+ * net/tcp/tcp_shutdown.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#ifdef CONFIG_NET_TCP
+
+#include <errno.h>
+#include <debug.h>
+#include <assert.h>
+
+#include <nuttx/net/net.h>
+#include <nuttx/net/netdev.h>
+#include <nuttx/net/tcp.h>
+
+#include "netdev/netdev.h"
+#include "devif/devif.h"
+#include "tcp/tcp.h"
+#include "socket/socket.h"
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: tcp_shutdown_eventhandler
+ ****************************************************************************/
+
+static uint16_t tcp_shutdown_eventhandler(FAR struct net_driver_s *dev,
+                                          FAR void *pvpriv, uint16_t flags)
+{
+  FAR struct tcp_conn_s *conn = pvpriv;
+
+  ninfo("flags: %04x\n", flags);
+
+#ifdef CONFIG_NET_TCP_WRITE_BUFFERS
+  /* We don't need the send callback anymore. */
+
+  if (conn->sndcb != NULL)
+    {
+      conn->sndcb->flags = 0;
+      conn->sndcb->event = NULL;
+
+      /* The callback will be freed by tcp_free. */
+
+      conn->sndcb = NULL;
+    }
+#endif
+
+  dev->d_len = 0;
+  flags = (flags & ~TCP_NEWDATA) | TCP_CLOSE;
+
+  if (conn->shdcb != NULL)
+    {
+      tcp_callback_free(conn, conn->shdcb);
+      conn->shdcb = NULL;
+    }
+
+  return flags;
+}
+
+/****************************************************************************
+ * Name: tcp_send_fin
+ *
+ * Description:
+ *   Send a FIN for TCP connection
+ *
+ * Input Parameters:
+ *   conn - TCP connection structure
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   Called from normal user-level logic
+ *
+ ****************************************************************************/
+
+static inline int tcp_send_fin(FAR struct socket *psock)
+{
+  FAR struct tcp_conn_s *conn;
+  int ret = OK;
+
+  /* Interrupts are disabled here to avoid race conditions */
+
+  net_lock();
+
+  conn = (FAR struct tcp_conn_s *)psock->s_conn;
+  DEBUGASSERT(conn != NULL);
+
+  if ((conn->tcpstateflags == TCP_ESTABLISHED ||
+       conn->tcpstateflags == TCP_SYN_SENT ||
+       conn->tcpstateflags == TCP_SYN_RCVD))
+    {
+      if ((conn->shdcb = tcp_callback_alloc(conn)) == NULL)
+        {
+          ret = -EBUSY;
+          goto out;
+        }
+
+      /* Set up to receive TCP data event callbacks */
+
+      conn->shdcb->flags = TCP_POLL;
+      conn->shdcb->event = tcp_shutdown_eventhandler;
+      conn->shdcb->priv  = conn; /* reference for event handler to free cb */
+
+      /* Notify the device driver of the availability of TX data */
+
+      tcp_send_txnotify(psock, conn);
+    }
+
+out:
+  net_unlock();
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: tcp_shutdown
+ *
+ * Description:
+ *   Gracefully shutdown a TCP connection by sending a FIN
+ *
+ * Input Parameters:
+ *   psock - An instance of the internal socket structure.
+ *   how   - Specifies the type of shutdown.
+ *
+ * Assumptions:
+ *   Called from normal user-level logic
+ *
+ ****************************************************************************/
+
+int tcp_shutdown(FAR struct socket *psock, int how)
+{
+  if (!(how & SHUT_WR))
+    {
+      return -EOPNOTSUPP;
+    }
+
+  tcp_unlisten(psock->s_conn); /* No longer accepting connections */
+
+  return tcp_send_fin(psock);
+}
+
+#endif /* CONFIG_NET_TCP */