[En-Nut-Discussion] src ip filtering addition

[Damian Slee]

Hi,
I have made a change to allow/drop IP in packets, ie filter.  
Can this be added to CVS? Attached modified ipin.c, ip.h from cvs yesterday.

Summary
-------
I have a callback function that I register with,
NutIpSetInputFilter(NutIpFilterFunc callbackFunc).

The callback receives the source IP address as a parmater.  It returns 0 for allow, -1 for deny.  The developer implements their own rule table.


e.g.  Allows all devices on subnet 192.168.0.0/255.255.255.0 to talk to ethernut.
u_long myFilterIp;
u_long myFilterMask;

int MyNutIpFilter(u_long  ip_src)
{
	if ((ip_src & myFilterMask) == myFilterIp)
		return 0;
	return -1;
}

main()
{
	// Do DHCP....
...
	myFilterIp = inet_addr("192.168.0.0");
	myFilterMask = inet_addr("255.255.255.0");
	NutIpSetInputFilter(MyNutIpFilter);
...
}

-----------------------------------------------------------
Changes to ipin.c
Addition
NutIpFilterFunc NutIpFilter = 0;
void NutIpSetInputFilter(NutIpFilterFunc callbackFunc)
{
	NutIpFilter = callbackFunc;
}

Change
void NutIpInput(NUTDEVICE * dev, NETBUF * nb)
{
...
    /*
     * Silently discard datagrams of different IP version
     * and fragmented datagrams, and Filtered IP datagrams
     */
    if (ip->ip_v != IPVERSION
        || (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) != 0
		||  (NutIpFilter && NutIpFilter(ip->ip_src)))
	{
        NutNetBufFree(nb);
        return;
    }
...
}
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