net: core: Verify interface state in net_try_send_data()

Verify that the interface is in operational UP state before attempting
to send the packet with net_send_data() / net_try_send_data().

So far there's only been an NET_IF_LOWER_UP check in a lower level
function, net_if_try_send_data(), however that didn't work well with
interface like Wi-Fi, whouch could have carrier state set to ON, but
was still not associated with the network (so the interface was no
operational UP). Protocols like ICMP or DHCP, which use net_send_data()
directly, should not be able to send packets in such case.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

subsys/net/ip/net_core.c

@@ -384,6 +384,11 @@ int net_try_send_data(struct net_pkt *pkt, k_timeout_t timeout)
 		goto err;
 	}
 
+	if (!net_if_is_up(net_pkt_iface(pkt))) {
+		ret = -ENETDOWN;
+		goto err;
+	}
+
 	net_pkt_trim_buffer(pkt);
 	net_pkt_cursor_init(pkt);