net: context: Check interface status when sending

If the network interface is down when trying to send a message,
return -ENETDOWN as we cannot send a message in this case.

Signed-off-by: Jukka Rissanen <[email protected]>

Author: jukkar

subsys/net/ip/net_context.c

@@ -1397,6 +1397,7 @@ static int context_sendto(struct net_context *context,
 			  bool sendto)
 {
 	const struct msghdr *msghdr = NULL;
+	struct net_if *iface;
 	struct net_pkt *pkt;
 	size_t tmp_len;
 	int ret;
@@ -1471,7 +1472,6 @@ static int context_sendto(struct net_context *context,
 	} else if (IS_ENABLED(CONFIG_NET_SOCKETS_PACKET) &&
 		   net_context_get_family(context) == AF_PACKET) {
 		struct sockaddr_ll *ll_addr = (struct sockaddr_ll *)dst_addr;
-		struct net_if *iface;
 
 		if (msghdr) {
 			ll_addr = msghdr->msg_name;
@@ -1520,7 +1520,6 @@ static int context_sendto(struct net_context *context,
 	} else if (IS_ENABLED(CONFIG_NET_SOCKETS_CAN) &&
 		   net_context_get_family(context) == AF_CAN) {
 		struct sockaddr_can *can_addr = (struct sockaddr_can *)dst_addr;
-		struct net_if *iface;
 
 		if (msghdr) {
 			can_addr = msghdr->msg_name;
@@ -1571,6 +1570,11 @@ static int context_sendto(struct net_context *context,
 		}
 	}
 
+	iface = net_context_get_iface(context);
+	if (iface && !net_if_is_up(iface)) {
+		return -ENETDOWN;
+	}
+
 	pkt = context_alloc_pkt(context, len, PKT_WAIT_TIME);
 	if (!pkt) {
 		return -ENOBUFS;