FreeRTOS_ARP.c : store local addresses only

[htibosch]

Description

Note: the name of my branch is incorrect, it should have been "arp_store_local_addresses_only", in stead of referring to "dhcp".

Three changes to FreeRTOS_ARP.c :

1. When ipconfigARP_STORES_REMOTE_ADDRESSES is 0, ARP doesn't want to store any non-local IP-address in the ARP cache.
   We made an exception, during the DHCP phase, when *ipLOCAL_IP_ADDRESS_POINTER is still zero, any address would be stored:

#if ( ipconfigARP_STORES_REMOTE_ADDRESSES == 0 )
    if( ( ( ulIPAddress & xNetworkAddressing.ulNetMask ) == ( ( *ipLOCAL_IP_ADDRESS_POINTER ) & xNetworkAddressing.ulNetMask ) ) ||
        ( *ipLOCAL_IP_ADDRESS_POINTER == 0UL ) )
    {
        /* Store the address. */
    }

DHCP doesn't need ARP beecause the client uses the IP broadcast address to find the DHCP server. I would like to change the test to:

#if ( ipconfigARP_STORES_REMOTE_ADDRESSES == 0 )
    /* Only process the IP address if it is on the local network. */
    if( ( ulIPAddress & xNetworkAddressing.ulNetMask ) == ( ( *ipLOCAL_IP_ADDRESS_POINTER ) & xNetworkAddressing.ulNetMask ) )
    {
        /* Store the address. */
    }

2. In the function eARPGetCacheEntry(), the MAC-address of the LLMNR IP-address was still set 'manually'. That is not necessary since it would have been set a few lines later in:

    if( xIsIPv4Multicast( ulAddressToLookup ) != 0 )
    {
        /* Get the lowest 23 bits of the IP-address. */
        vSetMultiCastIPv4MacAddress( ulAddressToLookup, pxMACAddress );
        eReturn = eARPCacheHit;
    }

3. Resolving the "own" IP-address in eARPGetCacheEntry() : I would like to add these lines:

    else if( *ipLOCAL_IP_ADDRESS_POINTER == *pulIPAddress )
    {
        /* The address of this device. May be useful for the loopback device. */
        eReturn = eARPCacheHit;
        memcpy( pxMACAddress->ucBytes, ipLOCAL_MAC_ADDRESS, sizeof( pxMACAddress->ucBytes ) );
    }

so that a loopback can be used.

4. And finally: the addition of xARPWaitResolution(). It can be called by the application to confirm that the MAC-address of a local device is known.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[AniruddhaKanhere]

@htibosch, can you try to fix the CI checks which are failing so that we can move ahead with the review? If there is some issue with the fix, feel free to ping me.
Thank you.

[htibosch]

CI Checks / unittest fails:

Linking FreeRTOS_TCP_Unit_test give a few errors because tasks.c is not linked in the unit test project?
These functions are ,missing:

vTaskSetTimeOutState
vTaskDelay needs INCLUDE_vTaskDelay = 1
`xTaskCheckForTimeOut

Could you check that please? Thanks.

[AniruddhaKanhere]

See the comments thanks!

[AniruddhaKanhere]

Why not use a pdFALSE instead of a 0 here?

[AniruddhaKanhere]

Where is this function declared? What I mean to say is that how can one use this function? What header file is required to add this?

[htibosch]

Ah sorry, I had declared it in FreeRTOS_IP.h, now updated.

[AniruddhaKanhere]

These are task.h specific functions. Are we sure that this will not break any existing projects?

[htibosch]

Updated FreeRTOS_IP.h and replaced 0 with pdFALSE in 2 occasions. Thanks

[htibosch]

Ah sorry, I had declared it in FreeRTOS_IP.h, now updated.