FreeRTOS+TCP 4.0.0 What is the "proper" way to change end-point settings

Libraries
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Hello @epopov,

As usual, I try to keep it short :slight_smile:

At this moment, FreeRTOS_FillEndPoint() will call FreeRTOS_AddEndPoint(), which has a problem. I discovered and solved it this week in PR #1020.

Also FreeRTOS_AddNetworkInterface() will need a small change.

Important to know: when xApplicationDHCPHook_Multi() is called, the code is running from the IP-task, so it is safe to make changes to the ipv4_defaults of the endpoint.

Here is an example that I just tested. Note that it is a quick sketch, just to explain and explore ideas.

First I have started the endpoint with these properties:

===>   Interface 'eth0' endpoint '0.0.0.0' is up
IPv4 address = 0.0.0.0
IP-address : 0.0.0.0
End-point  : up = yes method static
Net mask   : 255.255.255.0
GW         : 0.0.0.0
DNS-0      : 0.0.0.0
DNS-1      : 0.0.0.0
Broadcast  : 0.0.0.255
MAC address: 00-11-22-33-44-41

After 3 seconds I want to start DHCP:

static BaseType_t bDHCP_started = pdFALSE;

/* Only do this once, after running 3 seconds. */
if( ( bDHCP_started == pdFALSE ) &&
    ( xTaskGetTickCount () > pdMS_TO_TICKS( 3000U ) ) )
{
    /* Remember that DHCP was started. */
    bDHCP_started = pdTRUE;
    /* Set the DHCP bit. */
    xEndPoints[0].bits.bWantDHCP = pdTRUE;
    /* Put the endpoint in the down state. */
//  vApplicationIPNetworkEventHook_Multi( eNetworkDown, &( xEndPoints[ 0 ] ) );
/* Try this in stead: */
xEndPoints[ 0 ].bits.bEndPointUp = pdFALSE_UNSIGNED;

EDIT : probably not a good idea to call the network event hook from the application.
Actually I was looking for a function that brings a single endpoint in the eNetworkDown state.

    /* Tell the IP-task that DHCP must be re-started. */
    xSendDHCPEvent( &( xEndPoints[ 0 ] ) );
}

You may wat to stop the scheduler temporarily while running the above code.

Now I see that DHCP negotiation is starting again and my DHCP application hook is called:

eDHCPCallbackAnswer_t xApplicationDHCPHook_Multi( eDHCPCallbackPhase_t eDHCPPhase,
                                                  struct xNetworkEndPoint * pxEndPoint,
                                                  IP_Address_t * pxIPAddress )
{
    eDHCPCallbackAnswer_t aAnswer = eDHCPContinue;

    if( pxEndPoint->bits.bIPv6 == pdTRUE_UNSIGNED )
    {
        FreeRTOS_printf( ("DHCP[%d] IP %pip\n",
            ( int ) eDHCPPhase, pxIPAddress->xIP_IPv6.ucBytes) );
    }
    else
    {
        if( ( bEnableDHCP == pdFALSE ) && ( eDHCPPhase == eDHCPPhasePreDiscover ) )
        {
            /* Use a static address 192.168.2.199. */
            uint32_t ulIPAddress;
            FreeRTOS_inet_pton4( "192.168.2.199", ( void* )&ulIPAddress );
            uint8_t * pucIPAddress = (uint8_t * )&ulIPAddress;
            FreeRTOS_FillEndPoint( &(xInterfaces[0]),
                                   &(xEndPoints[0]),
                                   pucIPAddress,
                                   ucNetMask,
                                   ucGatewayAddress,
                                   ucDNSServerAddress,
                                   ucMACAddress );
            /* Just to make clear that DHCP was cancelled. */
            pxEndPoint->bits.bWantDHCP = pdFALSE;
            aAnswer = eDHCPUseDefaults;
        }
        FreeRTOS_printf( ("DHCP[%d] IP %xip\n",
            ( int ) eDHCPPhase, FreeRTOS_ntohl( pxIPAddress->ulIP_IPv4 ) ) );
    }
    return aAnswer;
}

My vApplicationIPNetworkEventHook_Multi() is called again when DHCP is ready or in case I stopped DHCP.

These are the new properties of the endpoint:

===>   Interface 'eth0' endpoint '192.168.2.199' is up
uxNetworkisUp = 5 expected 5
IPv4 address = 192.168.2.199
End-point  : up = yes method static
Net mask   : 255.255.255.0
GW         : 192.168.2.1
DNS-0      : 118.98.44.100
DNS-1      : 0.0.0.0
Broadcast  : 192.168.2.255
MAC address: 00-11-22-33-44-41

But once again: the FreeRTOS_FillEndPoint() can be called once for every endpoint until PR #1020 is applyied.

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