Before sending a challenge ACK, check the sequence number more properly (#225)

* Before sending a challenge ACK, check the sequence number more properly

* Make xSequenceLessThan and xSequenceGreaterThan public functions

* Extended comments on two public functions.

* Fix Spell check

* Although no changes were made to MPS2_AN385, some formatting changes to that driver

Co-authored-by: Hein Tibosch <[email protected]>
Co-authored-by: Aniruddha Kanhere <[email protected]>

Author: 3 people

.github/lexicon.txt

@@ -325,6 +325,7 @@ gmacsa
 gnw
 gpio
 gpl
+greaterthan
 grr
 gswutr
 hal
@@ -417,6 +418,7 @@ ldistance
 leds
 len
 lendofframe
+lessthan
 linkcurr
 linklayer
 linkmd

FreeRTOS_TCP_IP.c

@@ -3583,9 +3583,9 @@
                                 vTCPStateChange( pxSocket, eCLOSED );
                             }
                             /* Otherwise, check whether the packet is within the receive window. */
-                            else if( ( ulSequenceNumber > pxSocket->u.xTCP.xTCPWindow.rx.ulCurrentSequenceNumber ) &&
-                                     ( ulSequenceNumber < ( pxSocket->u.xTCP.xTCPWindow.rx.ulCurrentSequenceNumber +
-                                                            pxSocket->u.xTCP.xTCPWindow.xSize.ulRxWindowLength ) ) )
+                            else if( ( xSequenceGreaterThan( ulSequenceNumber, pxSocket->u.xTCP.xTCPWindow.rx.ulCurrentSequenceNumber ) ) &&
+                                     ( xSequenceLessThan( ulSequenceNumber, ( pxSocket->u.xTCP.xTCPWindow.rx.ulCurrentSequenceNumber +
+                                                                              pxSocket->u.xTCP.xTCPWindow.xSize.ulRxWindowLength ) ) ) )
                             {
                                 /* Send a challenge ACK. */
                                 ( void ) prvTCPSendChallengeAck( pxNetworkBuffer );

FreeRTOS_TCP_WIN.c

@@ -269,10 +269,6 @@
     #endif /* ipconfigUSE_TCP_WIN */
 /*-----------------------------------------------------------*/
 
-    #if ( ipconfigUSE_TCP_WIN == 1 )
-        static portINLINE BaseType_t xSequenceLessThan( uint32_t a,
-                                                        uint32_t b );
-
 /**
  * @brief Check if a < b.
  *
@@ -281,30 +277,25 @@
  *
  * @return pdTRUE when "( b - ( a + 1 ) ) < 0x80000000", else pdFALSE.
  */
-        static portINLINE BaseType_t xSequenceLessThan( uint32_t a,
-                                                        uint32_t b )
-        {
-            BaseType_t xResult;
-
-            /* Test if a < b */
-            if( ( ( b - ( a + 1UL ) ) & 0x80000000UL ) == 0UL )
-            {
-                xResult = pdTRUE;
-            }
-            else
-            {
-                xResult = pdFALSE;
-            }
+    BaseType_t xSequenceLessThan( uint32_t a,
+                                  uint32_t b )
+    {
+        BaseType_t xResult;
 
-            return xResult;
+        /* Test if a < b */
+        if( ( ( b - ( a + 1UL ) ) & 0x80000000UL ) == 0UL )
+        {
+            xResult = pdTRUE;
+        }
+        else
+        {
+            xResult = pdFALSE;
         }
 
-    #endif /* ipconfigUSE_TCP_WIN */
-/*-----------------------------------------------------------*/
+        return xResult;
+    }
 
-    #if ( ipconfigUSE_TCP_WIN == 1 )
-        static portINLINE BaseType_t xSequenceGreaterThan( uint32_t a,
-                                                           uint32_t b );
+/*-----------------------------------------------------------*/
 
 /**
  * @brief Check if a > b.
@@ -314,25 +305,24 @@
  *
  * @return pdTRUE when "( a - b ) < 0x80000000", else pdFALSE.
  */
-        static portINLINE BaseType_t xSequenceGreaterThan( uint32_t a,
-                                                           uint32_t b )
-        {
-            BaseType_t xResult;
-
-            /* Test if a > b */
-            if( ( ( a - ( b + 1UL ) ) & 0x80000000UL ) == 0UL )
-            {
-                xResult = pdTRUE;
-            }
-            else
-            {
-                xResult = pdFALSE;
-            }
+    BaseType_t xSequenceGreaterThan( uint32_t a,
+                                     uint32_t b )
+    {
+        BaseType_t xResult;
 
-            return xResult;
+        /* Test if a > b */
+        if( ( ( a - ( b + 1UL ) ) & 0x80000000UL ) == 0UL )
+        {
+            xResult = pdTRUE;
+        }
+        else
+        {
+            xResult = pdFALSE;
         }
 
-    #endif /* ipconfigUSE_TCP_WIN */
+        return xResult;
+    }
+
 
 /*-----------------------------------------------------------*/
     static portINLINE BaseType_t xSequenceGreaterThanOrEqual( uint32_t a,

include/FreeRTOS_TCP_WIN.h

@@ -229,6 +229,31 @@
                                 uint32_t ulFirst,
                                 uint32_t ulLast );
 
+/**
+ * @brief Check if a > b, where a and b are rolling counters.
+ *
+ * @param[in] a: The value on the left-hand side.
+ * @param[in] b: The value on the right-hand side.
+ *
+ * @return pdTRUE if a > b, otherwise pdFALSE.
+ *
+ * @note GreaterThan is calculated as "( a - ( b + 1U ) ) < 0x80000000".
+ */
+    BaseType_t xSequenceGreaterThan( uint32_t a,
+                                     uint32_t b );
+
+/**
+ * @brief Check if a < b, where a and b are rolling counters.
+ *
+ * @param[in] a: The value on the left-hand side.
+ * @param[in] b: The value on the right-hand side.
+ *
+ * @return pdTRUE if a < b, otherwise pdFALSE.
+ *
+ * @note LessThan is implemented as "( b - ( a + 1 ) ) < 0x80000000".
+ */
+    BaseType_t xSequenceLessThan( uint32_t a,
+                                  uint32_t b );
 
     #ifdef __cplusplus
         } /* extern "C" */