[IPV4]: Snmpv2 Mib IP counter ipInAddrErrors support

I followed Thomas' proposal to see every martian destination as a case
where the ipInAddrErrors counter has to be incremented. There are
two advantages by doing so: (1) The relation between the ipInReceive
counter and all the other ipInXXX counters is more accurate in the
case the RTN_UNICAST code check fails and (2) it makes the code in
ip_route_input_slow easier.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 80cf633..12a1cf3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1909,7 +1909,7 @@
 	 */
 	if ((err = fib_lookup(&fl, &res)) != 0) {
 		if (!IN_DEV_FORWARD(in_dev))
-			goto e_inval;
+			goto e_hostunreach;
 		goto no_route;
 	}
 	free_res = 1;
@@ -1933,7 +1933,7 @@
 	}
 
 	if (!IN_DEV_FORWARD(in_dev))
-		goto e_inval;
+		goto e_hostunreach;
 	if (res.type != RTN_UNICAST)
 		goto martian_destination;
 
@@ -2025,6 +2025,11 @@
 			"%u.%u.%u.%u, dev %s\n",
 			NIPQUAD(daddr), NIPQUAD(saddr), dev->name);
 #endif
+
+e_hostunreach:
+        err = -EHOSTUNREACH;
+        goto done;
+
 e_inval:
 	err = -EINVAL;
 	goto done;