From e86207c4c8c39f7c86fa031bb742cce25073d20b Mon Sep 17 00:00:00 2001
From: Hein Tibosch <hein_tibosch@yahoo.es>
Date: Wed, 8 Feb 2023 12:11:39 +0800
Subject: [PATCH] Make sure that a TCP socket is closed only once

---
 source/FreeRTOS_TCP_IP.c             | 33 ++++++++++++++++++++--------
 source/include/FreeRTOS_IP_Private.h | 20 +++++++++++++----
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/source/FreeRTOS_TCP_IP.c b/source/FreeRTOS_TCP_IP.c
index 7db7737267..995173573d 100644
--- a/source/FreeRTOS_TCP_IP.c
+++ b/source/FreeRTOS_TCP_IP.c
@@ -445,27 +445,42 @@
             }
         }
 
+        /* Fill in the new state. */
+        pxSocket->u.xTCP.eTCPState = eTCPState;
+
         if( ( eTCPState == eCLOSED ) ||
             ( eTCPState == eCLOSE_WAIT ) )
         {
             /* Socket goes to status eCLOSED because of a RST.
              * When nobody owns the socket yet, delete it. */
-            if( ( pxSocket->u.xTCP.bits.bPassQueued != pdFALSE_UNSIGNED ) ||
-                ( pxSocket->u.xTCP.bits.bPassAccept != pdFALSE_UNSIGNED ) )
+            vTaskSuspendAll();
             {
-                FreeRTOS_debug_printf( ( "vTCPStateChange: Closing socket\n" ) );
+                if( ( pxSocket->u.xTCP.bits.bPassQueued != pdFALSE_UNSIGNED ) ||
+                    ( pxSocket->u.xTCP.bits.bPassAccept != pdFALSE_UNSIGNED ) )
+                {
+                    if( pxSocket->u.xTCP.bits.bReuseSocket == pdFALSE_UNSIGNED )
+                    {
+                        pxSocket->u.xTCP.bits.bPassQueued = pdFALSE_UNSIGNED;
+                        pxSocket->u.xTCP.bits.bPassAccept = pdFALSE_UNSIGNED;
+                    }
 
-                if( pxSocket->u.xTCP.bits.bReuseSocket == pdFALSE_UNSIGNED )
+                    xTaskResumeAll();
+
+                    FreeRTOS_printf( ( "vTCPStateChange: Closing socket\n" ) );
+
+                    if( pxSocket->u.xTCP.bits.bReuseSocket == pdFALSE_UNSIGNED )
+                    {
+                        configASSERT( xIsCallingFromIPTask() != pdFALSE );
+                        vSocketCloseNextTime( pxSocket );
+                    }
+                }
+                else
                 {
-                    configASSERT( xIsCallingFromIPTask() != pdFALSE );
-                    vSocketCloseNextTime( pxSocket );
+                    xTaskResumeAll();
                 }
             }
         }
 
-        /* Fill in the new state. */
-        pxSocket->u.xTCP.eTCPState = eTCPState;
-
         if( ( eTCPState == eCLOSE_WAIT ) && ( pxSocket->u.xTCP.bits.bReuseSocket == pdTRUE_UNSIGNED ) )
         {
             switch( xPreviousState )
diff --git a/source/include/FreeRTOS_IP_Private.h b/source/include/FreeRTOS_IP_Private.h
index 411cf9cb1b..542c28b247 100644
--- a/source/include/FreeRTOS_IP_Private.h
+++ b/source/include/FreeRTOS_IP_Private.h
@@ -508,6 +508,20 @@ BaseType_t xIPIsNetworkTaskReady( void );
  */
     TickType_t xTCPTimerCheck( BaseType_t xWillSleep );
 
+/**
+ * About the TCP flags 'bPassQueued' and 'bPassAccept':
+ *
+ * When a new TCP connection request is received on a listening socket, the bPassQueued and
+ * bPassAccept members of the newly created socket are updated as follows:
+ *
+ * 1. bPassQueued is set to indicate that the 3-way TCP handshake is in progress.
+ * 2. When the 3-way TCP handshake is complete, bPassQueued is cleared. At the same time,
+ *    bPassAccept is set to indicate that the socket is ready to be picked up by the task
+ *    that called FreeRTOS_accept().
+ * 3. When the socket is picked up by the task that called FreeRTOS_accept, the bPassAccept
+ *    is cleared.
+ */
+
 /**
  * Every TCP socket has a buffer space just big enough to store
  * the last TCP header received.
@@ -544,10 +558,8 @@ BaseType_t xIPIsNetworkTaskReady( void );
             /* Most compilers do like bit-flags */
             uint32_t
                 bMssChange : 1,        /**< This socket has seen a change in MSS */
-                bPassAccept : 1,       /**< when true, this socket may be returned in a call to accept() */
-                bPassQueued : 1,       /**< when true, this socket is an orphan until it gets connected
-                                        * Why an orphan? Because it may not be returned in a accept() call until it
-                                        * gets the state eESTABLISHED */
+                bPassAccept : 1,       /**< See comment here above. */
+                bPassQueued : 1,       /**< See comment here above. */
                 bReuseSocket : 1,      /**< When a listening socket gets a connection, do not create a new instance but keep on using it */
                 bCloseAfterSend : 1,   /**< As soon as the last byte has been transmitted, finalise the connection
                                         * Useful in e.g. FTP connections, where the last data bytes are sent along with the FIN flag */