Networking: TCP disconnection callbacks are not retained in a list. This will support mutiple callbacks per lower-level TCP connection structure. That is necessary for the cae where a socket is dup'ed and shares the same lower-level connection structure. NOTE: There still needs to be a call to tcp_start_monitor() when the socket is dup'ed.

net/tcp/tcp.h

@@ -74,15 +74,6 @@
 #define tcp_callback_free(conn,cb) \
   devif_conn_callback_free((conn)->dev, (cb), &(conn)->list)
 
-/* These macros allocate and free callback structures used for receiving
- * notifications of device-related events.
- */
-
-#define tcp_monitor_callback_alloc(conn) \
-  devif_callback_alloc((conn)->dev, NULL)
-#define tcp_monitor_callback_free(conn,cb) \
-  devif_conn_callback_free((conn)->dev, (cb), NULL)
-
 #ifdef CONFIG_NET_TCP_WRITE_BUFFERS
 /* TCP write buffer access macros */
 
@@ -231,6 +222,14 @@ struct tcp_conn_s
 
   FAR struct devif_callback_s *list;
 
+  /* connevents is a list of callbacks for each socket the uses this
+   * connection (there can be more that one in the event that the the socket
+   * was dup'ed).  It is used with the network monitor to handle
+   * asynchronous loss-of-connection events.
+   */
+
+  FAR struct devif_callback_s *connevents;
+
   /* accept() is called when the TCP logic has created a connection
    *
    *   accept_private: This is private data that will be available to the
@@ -241,24 +240,6 @@ struct tcp_conn_s
 
   FAR void *accept_private;
   int (*accept)(FAR struct tcp_conn_s *listener, FAR struct tcp_conn_s *conn);
-
-  /* connection_event() is called on any of the subset of connection-related
-   * events.
-   *
-   *   connection_private: This is private data that will be available to
-   *     the connection_event() handler when it is invoked with a point to
-   *     this structure as an argument.
-   *   connection_devcb: this is the allocated callback structure that is
-   *     used to
-   *   connection_event: This is the pointer to the connection event
-   *     handler.
-   */
-
-  FAR void *connection_private;
-  FAR struct devif_callback_s *connection_devcb;
-  uint16_t (*connection_event)(FAR struct net_driver_s *dev,
-                               FAR void *pvconn, FAR void *pvpriv,
-                               uint16_t flags);
 };
 
 /* This structure supports TCP write buffering */

net/tcp/tcp_callback.c

@@ -193,12 +193,11 @@ uint16_t tcp_callback(FAR struct net_driver_s *dev,
    * callback.
    */
 
-  if (((flags & TCP_CONN_EVENTS) != 0) && conn->connection_event)
+  if ((flags & TCP_CONN_EVENTS) != 0)
     {
-      /* Perform the callback */
+      /* Perform the callback disconnect callbacks */
 
-      flags = conn->connection_event(dev, conn, conn->connection_private,
+      flags = devif_conn_event(dev, conn, flags, conn->connevents);
-                                     flags);
     }
 
   return flags;

net/tcp/tcp_monitor.c

@@ -56,8 +56,8 @@
  * Private Function Prototypes
  ****************************************************************************/
 
-static void connection_closed(FAR struct socket *psock, uint16_t flags);
+static void tcp_close_connection(FAR struct socket *psock, uint16_t flags);
-static uint16_t connection_event(FAR struct net_driver_s *dev,
+static uint16_t tcp_disconnect_event(FAR struct net_driver_s *dev,
                                  FAR void *pvconn, FAR void *pvpriv,
                                  uint16_t flags);
 
@@ -66,7 +66,7 @@ static uint16_t connection_event(FAR struct net_driver_s *dev,
  ****************************************************************************/
 
 /****************************************************************************
- * Name: connection_closed
+ * Name: tcp_close_connection
  *
  * Description:
  *   Called when a loss-of-connection event has occurred.
@@ -83,7 +83,7 @@ static uint16_t connection_event(FAR struct net_driver_s *dev,
  *
  ****************************************************************************/
 
-static void connection_closed(FAR struct socket *psock, uint16_t flags)
+static void tcp_close_connection(FAR struct socket *psock, uint16_t flags)
 {
   /* These loss-of-connection events may be reported:
    *
@@ -121,7 +121,7 @@ static void connection_closed(FAR struct socket *psock, uint16_t flags)
 }
 
 /****************************************************************************
- * Name: connection_event
+ * Name: tcp_disconnect_event
  *
  * Description:
  *   Some connection related event has occurred
@@ -139,13 +139,13 @@ static void connection_closed(FAR struct socket *psock, uint16_t flags)
  *
  ****************************************************************************/
 
-static uint16_t connection_event(FAR struct net_driver_s *dev,
+static uint16_t tcp_disconnect_event(FAR struct net_driver_s *dev,
-                                 FAR void *pvconn, FAR void *pvpriv,
+                                     FAR void *pvconn, FAR void *pvpriv,
-                                 uint16_t flags)
+                                     uint16_t flags)
 {
   FAR struct socket *psock = (FAR struct socket *)pvpriv;
 
-  if (psock)
+  if (psock != NULL)
     {
       ninfo("flags: %04x s_flags: %02x\n", flags, psock->s_flags);
 
@@ -155,7 +155,7 @@ static uint16_t connection_event(FAR struct net_driver_s *dev,
 
       if ((flags & TCP_DISCONN_EVENTS) != 0)
         {
-          connection_closed(psock, flags);
+          tcp_close_connection(psock, flags);
         }
 
       /* TCP_CONNECTED: The socket is successfully connected */
@@ -188,9 +188,51 @@ static uint16_t connection_event(FAR struct net_driver_s *dev,
   return flags;
 }
 
+/****************************************************************************
+ * Name: tcp_shutdown_monitor
+ *
+ * Description:
+ *   Stop monitoring TCP connection changes for a given socket.
+ *
+ * Input Parameters:
+ *   conn  - The TCP connection of interest
+ *   flags - Indicates the type of shutdown.  TCP_CLOSE or TCP_ABORT
+ *
+ * Returned Value:
+ *   None
+ *
+ * Assumptions:
+ *   The caller holds the network lock (if not, it will be locked momentarily
+ *   by this function).
+ *
+ ****************************************************************************/
+
+void tcp_shutdown_monitor(FAR struct tcp_conn_s *conn, uint16_t flags)
+{
+  DEBUGASSERT(conn);
+
+  /* Perform callbacks to assure that all sockets, including dup'ed copies,
+   * are informed of the loss of connection event.
+   */
+
+  net_lock();
+  (void)tcp_callback(conn->dev, conn, flags);
+
+  /* Free all allocated connection event callback structure s*/
+
+  while (conn->connevents != NULL)
+    {
+      devif_conn_callback_free(conn->dev, conn->connevents,
+                               &conn->connevents);
+    }
+
+  net_unlock();
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
+
 /****************************************************************************
  * Name: tcp_start_monitor
  *
@@ -231,13 +273,7 @@ int tcp_start_monitor(FAR struct socket *psock)
     {
       /* Invoke the TCP_CLOSE connection event now */
 
-      (void)connection_event(NULL, conn, psock, TCP_CLOSE);
+      tcp_shutdown_monitor(conn, TCP_CLOSE);
-
-      /* Make sure that the monitor is stopped */
-
-      conn->connection_private = NULL;
-      conn->connection_devcb   = NULL;
-      conn->connection_event   = NULL;
 
       /* And return -ENOTCONN to indicate the monitor was not started
        * because the socket was already disconnected.
@@ -247,28 +283,18 @@ int tcp_start_monitor(FAR struct socket *psock)
       return -ENOTCONN;
     }
 
-  DEBUGASSERT(conn->connection_event == NULL &&
-              conn->connection_devcb == NULL);
-
   /* Allocate a callback structure that we will use to get callbacks if
    * the network goes down.
    */
 
-  cb = tcp_monitor_callback_alloc(conn);
+  cb = devif_callback_alloc(conn->dev, &conn->connevents);
   if (cb != NULL)
     {
-      cb->event = connection_event;
+      cb->event = tcp_disconnect_event;
       cb->priv  = (FAR void *)psock;
-      cb->flags = NETDEV_DOWN;
+      cb->flags = TCP_DISCONN_EVENTS;
     }
 
-  conn->connection_devcb = cb;
-
-  /* Set up to receive callbacks on connection-related events */
-
-  conn->connection_private = (FAR void *)psock;
-  conn->connection_event   = connection_event;
-
   net_unlock();
   return OK;
 }
@@ -277,7 +303,8 @@ int tcp_start_monitor(FAR struct socket *psock)
  * Name: tcp_stop_monitor
  *
  * Description:
- *   Stop monitoring TCP connection changes for a given socket
+ *   Stop monitoring TCP connection changes for a given socket.  This is part
+ *   of a graceful shutdown.
  *
  * Input Parameters:
  *   conn - The TCP connection of interest
@@ -293,33 +320,23 @@ int tcp_start_monitor(FAR struct socket *psock)
 
 void tcp_stop_monitor(FAR struct tcp_conn_s *conn)
 {
-  DEBUGASSERT(conn);
+  DEBUGASSERT(conn != NULL);
 
-  /* Free any allocated device event callback structure */
+  /* Stop the network monitor */
 
-  net_lock();
+  tcp_shutdown_monitor(conn, TCP_CLOSE);
-  if (conn->connection_devcb)
-    {
-      tcp_monitor_callback_free(conn, conn->connection_devcb);
-    }
-
-  /* Nullify all connection event data */
-
-  conn->connection_private = NULL;
-  conn->connection_devcb   = NULL;
-  conn->connection_event   = NULL;
-  net_unlock();
 }
 
 /****************************************************************************
  * Name: tcp_lost_connection
  *
  * Description:
- *   Called when a loss-of-connection event has occurred.
+ *   Called when a loss-of-connection event has occurred.  This is for an
+ *   unexpected disconnection of some sort from the host.
  *
  * Parameters:
- *   psock    The TCP socket structure associated.
+ *   psock - The TCP socket structure associated.
- *   flags    Set of connection events events
+ *   flags - Set of connection events events
  *
  * Returned Value:
  *   None
@@ -334,15 +351,9 @@ void tcp_lost_connection(FAR struct socket *psock, uint16_t flags)
 {
   DEBUGASSERT(psock != NULL && psock->s_conn != NULL);
 
-  /* Close the connection */
-
-  net_lock();
-  connection_closed(psock, flags);
-
   /* Stop the network monitor */
 
-  tcp_stop_monitor((FAR struct tcp_conn_s *)psock->s_conn);
+  tcp_shutdown_monitor((FAR struct tcp_conn_s *)psock->s_conn, flags);
-  net_unlock();
 }
 
 #endif /* NET_TCP_HAVE_STACK */