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FreeRTOS+TCP_Multi Bug: ARP resolves remote addresses locally

Posted by miclam on August 11, 2017


I'm currently testing the DNS client of +TCPmulti. When using as DNS server I noticed, that eARPGetCacheEntry does not resolve unmatched remote ip addresses to the default gateway. This is because FreeRTOSFindEndPointOnNetMask returns either the correct EndPoint, or the default EndPoint, and only in case no default is set NULL. eARPGetCacheEntry then checks by if( pxEndPoint == NULL ) (Line 456 in FreeRTOS_ARP.c) if the default gateway should be used, which is never reached.

My idea was to let FreeRTOSFindEndPointOnNetMask return NULL instead of the default EndPoint, and to explicitly call FreeRTOSFindDefaultEndPoint wherever the default EndPoint is required. But FreeRTOS_FindEndPointOnNetMask is used in quiet a lot locations, I'm afraid of breaking something without knowing.

What do you think?

Many thanks, Michael

FreeRTOS+TCP_Multi Bug: ARP resolves remote addresses locally

Posted by miclam on August 11, 2017

Hello, as far as I can see commenting out pxEndPoint = pxDefault; in Line 375 in FreeRTOSRouting.c and changing Line 2655 in FreeRTOSIP.c and Line 195 in FreeRTOSUDPIP.c to

        pxNetworkBuffer->pxEndPoint = FreeRTOS_FindEndPointOnNetMask( pxIPPacket->xIPHeader.ulDestinationIPAddress, 7 );
        /* _ML_ Removed default EndPoint from FreeRTOS_FindEndPointOnNetMask, so get it here if needed. */
        if( pxNetworkBuffer->pxEndPoint == NULL )
            pxNetworkBuffer->pxEndPoint = FreeRTOS_FindDefaultEndPoint();

works. The other occurences of FreeRTOS_FindEndPointOnNetMask seem to actually expect it not to return the default gateway.

Regards, Michael

FreeRTOS+TCP_Multi Bug: ARP resolves remote addresses locally

Posted by heinbali01 on August 11, 2017

See my reponse here

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