Bugfix in ATSAME5x network interface. Incorrect detection of ICMP (#1194)

Bugfix in ATSAME5x network interface. Incorrect detection of ICMP packets when CRC offloading is enabled.

Co-authored-by: Adam B. <adamb@videx.com>

Author: cruxic

source/portable/NetworkInterface/ATSAME5x/NetworkInterface.c

@@ -90,6 +90,9 @@
 static uint8_t ucLLMNR_MAC_address[] = { 0x01, 0x00, 0x5E, 0x00, 0x00, 0xFC };
 #endif
 
+/* Check if the raw Ethernet frame is ICMP */
+static BaseType_t isICMP( const NetworkBufferDescriptor_t * pxDescriptor );
+
 /* Receive task refresh time */
 #define RECEIVE_BLOCK_TIME_MS    100
 
@@ -272,14 +275,41 @@ BaseType_t xATSAM5x_NetworkInterfaceInitialise( NetworkInterface_t * pxInterface
     return xATSAM5x_PHYGetLinkStatus( NULL );
 }
 
+/* Check if the raw Ethernet frame is ICMP */
+static BaseType_t isICMP( const NetworkBufferDescriptor_t * pxDescriptor )
+{
+    BaseType_t xReturn = pdFALSE;
+
+    const IPPacket_t * pkt = ( const IPPacket_t * ) pxDescriptor->pucEthernetBuffer;
+
+    if( pkt->xEthernetHeader.usFrameType == ipIPv4_FRAME_TYPE )
+    {
+        if( pkt->xIPHeader.ucProtocol == ( uint8_t ) ipPROTOCOL_ICMP )
+        {
+            xReturn = pdTRUE;
+        }
+    }
+
+    #if ipconfigUSE_IPv6 != 0
+        else if( pkt->xEthernetHeader.usFrameType == ipIPv6_FRAME_TYPE )
+        {
+            ICMPPacket_IPv6_t * icmp6 = ( ICMPPacket_IPv6_t * ) pxDescriptor->pucEthernetBuffer;
+
+            if( icmp6->xIPHeader.ucNextHeader == ipPROTOCOL_ICMP_IPv6 )
+            {
+                xReturn = pdTRUE;
+            }
+        }
+    #endif
+    return xReturn;
+}
 
 static void prvEMACDeferredInterruptHandlerTask( void * pvParameters )
 {
     NetworkBufferDescriptor_t * pxBufferDescriptor;
     size_t xBytesReceived = 0, xBytesRead = 0;
 
     uint16_t xICMPChecksumResult = ipCORRECT_CRC;
-    const IPPacket_t * pxIPPacket;
 
 
     /* Used to indicate that xSendEventStructToIPTask() is being called because
@@ -336,15 +366,13 @@ static void prvEMACDeferredInterruptHandlerTask( void * pvParameters )
                     {
                         /* the Atmel SAM GMAC peripheral does not support hardware CRC offloading for ICMP packets.
                          * It must therefore be implemented in software. */
-                        pxIPPacket = ( IPPacket_t const * ) pxBufferDescriptor->pucEthernetBuffer;
-
-                        if( pxIPPacket->xIPHeader.ucProtocol == ( uint8_t ) ipPROTOCOL_ICMP )
+                        if( isICMP( pxBufferDescriptor ) == pdTRUE )
                         {
                             xICMPChecksumResult = usGenerateProtocolChecksum( pxBufferDescriptor->pucEthernetBuffer, pxBufferDescriptor->xDataLength, pdFALSE );
                         }
                         else
                         {
-                            xICMPChecksumResult = ipCORRECT_CRC; /* Reset the result value in case this is not an ICMP packet. */
+                            xICMPChecksumResult = ipCORRECT_CRC; /* Checksum already verified by GMAC */
                         }
                     }
                     #endif /* if ( ipconfigDRIVER_INCLUDED_RX_IP_CHECKSUM == 1 ) */
@@ -440,9 +468,7 @@ BaseType_t xATSAM5x_NetworkInterfaceOutput( NetworkInterface_t * pxInterface,
         {
             /* the Atmel SAM GMAC peripheral does not support hardware CRC offloading for ICMP packets.
              * It must therefore be implemented in software. */
-            const IPPacket_t * pxIPPacket = ( IPPacket_t const * ) pxDescriptor->pucEthernetBuffer;
-
-            if( pxIPPacket->xIPHeader.ucProtocol == ( uint8_t ) ipPROTOCOL_ICMP )
+            if( isICMP( pxDescriptor ) == pdTRUE )
             {
                 ( void ) usGenerateProtocolChecksum( pxDescriptor->pucEthernetBuffer, pxDescriptor->xDataLength, pdTRUE );
             }