Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Changes the ND cache full behavior when the Neighbor Discovery cache fills up. #1040

Merged
merged 3 commits into from
Nov 6, 2023
+34 −16
Merged

Changes the ND cache full behavior when the Neighbor Discovery cache fills up. #1040

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
84ac028
Changes the ND cache full behavior: If the Neighbor Discovery cache e…
Nov 1, 2023
d268afe
Adds casting to avoid warnings
Nov 2, 2023
00f9bd1
Merge branch 'main' into ND_FullCacheIssue_PR
tony-josi-aws Nov 3, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
50 changes: 34 additions & 16 deletions source/FreeRTOS_ND.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,8 @@
{
BaseType_t x;
BaseType_t xFreeEntry = -1, xEntryFound = -1;
BaseType_t xOldestValue = ipconfigMAX_ARP_AGE + 1;
BaseType_t xOldestEntry = 0;

/* For each entry in the ND cache table. */
for( x = 0; x < ipconfigND_CACHE_ENTRIES; x++ )
Expand All @@ -304,29 +306,45 @@
else
{
/* Entry is valid but the IP-address doesn't match. */

/* Keep track of the oldest entry in case we need to overwrite it. The problem we are trying to avoid is
* that there may be a queued packet in pxARPWaitingNetworkBuffer and we may have just received the
* neighbor advertisement needed for that packet. If we don't store this network advertisement in cache,
* the parting of the frame from pxARPWaitingNetworkBuffer will cause the sending of neighbor solicitation
* and stores the frame in pxARPWaitingNetworkBuffer. This becomes a vicious circle with thousands of
* neighbor solicitation/advertisement packets going back and forth because the ND cache is full.
* Overwriting the oldest cache entry is not a fool-proof solution, but it's something. */
if( xNDCache[ x ].ucAge < xOldestValue )
{
xOldestValue = xNDCache[ x ].ucAge;
xOldestEntry = x;
}
}
}

if( xEntryFound < 0 )
{
/* The IP-address was not found, use the first free location. */
xEntryFound = xFreeEntry;
if( xFreeEntry >= 0 )
{
xEntryFound = xFreeEntry;
}
else
{
/* No free location. Overwrite the oldest. */
xEntryFound = xOldestEntry;
FreeRTOS_printf( ( "vNDRefreshCacheEntry: Cache FULL! Overwriting oldest entry %i with %02X-%02X-%02X-%02X-%02X-%02X\n", ( int ) xEntryFound, pxMACAddress->ucBytes[ 0 ], pxMACAddress->ucBytes[ 1 ], pxMACAddress->ucBytes[ 2 ], pxMACAddress->ucBytes[ 3 ], pxMACAddress->ucBytes[ 4 ], pxMACAddress->ucBytes[ 5 ] ) );
}
}

if( xEntryFound >= 0 )
{
/* Copy the IP-address. */
( void ) memcpy( xNDCache[ xEntryFound ].xIPAddress.ucBytes, pxIPAddress->ucBytes, ipSIZE_OF_IPv6_ADDRESS );
/* Copy the MAC-address. */
( void ) memcpy( xNDCache[ xEntryFound ].xMACAddress.ucBytes, pxMACAddress->ucBytes, sizeof( MACAddress_t ) );
xNDCache[ xEntryFound ].pxEndPoint = pxEndPoint;
xNDCache[ xEntryFound ].ucAge = ( uint8_t ) ipconfigMAX_ARP_AGE;
xNDCache[ xEntryFound ].ucValid = ( uint8_t ) pdTRUE;
}
else
{
FreeRTOS_printf( ( "vNDRefreshCacheEntry: %pip not found\n", ( void * ) pxIPAddress->ucBytes ) );
}
/* At this point, xEntryFound is always a valid index. */
/* Copy the IP-address. */
( void ) memcpy( xNDCache[ xEntryFound ].xIPAddress.ucBytes, pxIPAddress->ucBytes, ipSIZE_OF_IPv6_ADDRESS );
/* Copy the MAC-address. */
( void ) memcpy( xNDCache[ xEntryFound ].xMACAddress.ucBytes, pxMACAddress->ucBytes, sizeof( MACAddress_t ) );
xNDCache[ xEntryFound ].pxEndPoint = pxEndPoint;
xNDCache[ xEntryFound ].ucAge = ( uint8_t ) ipconfigMAX_ARP_AGE;
xNDCache[ xEntryFound ].ucValid = ( uint8_t ) pdTRUE;
}
/*-----------------------------------------------------------*/

Expand Down Expand Up @@ -482,7 +500,7 @@
char pcBuffer[ 40 ];

/* Loop through each entry in the ND cache. */
for( x = 0; x < ipconfigARP_CACHE_ENTRIES; x++ )
for( x = 0; x < ipconfigND_CACHE_ENTRIES; x++ )
{
if( xNDCache[ x ].ucValid != ( uint8_t ) 0U )
{
Expand Down