net: ipv4_autoconf: Fix requested IPv4 address in ARP packet

Unspecified address 0.0.0.0 was used as a requested IPv4 address
because the ARP message was generated second time. So for IPv4
autoconf ARP message, generate the message only once.

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

Author: jukkar

subsys/net/l2/ethernet/arp.c

@@ -234,7 +234,6 @@ static inline struct net_pkt *arp_prepare(struct net_if *iface,
 					  struct in_addr *next_addr,
 					  struct arp_entry *entry,
 					  struct net_pkt *pending,
-					  struct in_addr *request_ip,
 					  struct in_addr *current_ip)
 {
 #if defined(CONFIG_NET_VLAN)
@@ -259,6 +258,8 @@ static inline struct net_pkt *arp_prepare(struct net_if *iface,
 		 * things setup so no need to allocate new net_pkt
 		 */
 		pkt = pending;
+
+		net_buf_add(pkt->frags, sizeof(struct net_arp_hdr));
 	} else {
 		pkt = net_pkt_get_reserve_tx(eth_hdr_len, NET_BUF_TIMEOUT);
 		if (!pkt) {
@@ -378,7 +379,8 @@ struct net_pkt *net_arp_prepare(struct net_pkt *pkt,
 	/* Is the destination in the local network, if not route via
 	 * the gateway address.
 	 */
-	if (!net_if_ipv4_addr_mask_cmp(net_pkt_iface(pkt), request_ip)) {
+	if (!current_ip &&
+	    !net_if_ipv4_addr_mask_cmp(net_pkt_iface(pkt), request_ip)) {
 		struct net_if_ipv4 *ipv4 = net_pkt_iface(pkt)->config.ip.ipv4;
 
 		if (ipv4) {
@@ -417,7 +419,7 @@ struct net_pkt *net_arp_prepare(struct net_pkt *pkt,
 		}
 
 		req = arp_prepare(net_pkt_iface(pkt), addr, entry, pkt,
-				  request_ip, current_ip);
+				  current_ip);
 
 		if (!entry) {
 			/* We cannot send the packet, the ARP cache is full
@@ -437,7 +439,8 @@ struct net_pkt *net_arp_prepare(struct net_pkt *pkt,
 		net_sprint_ipv4_addr(&NET_IPV4_HDR(pkt)->src));
 
 	net_eth_fill_header(ctx, pkt,
-			    htons(NET_ETH_PTYPE_IP),
+			    current_ip == NULL ? htons(NET_ETH_PTYPE_IP) :
+						 htons(NET_ETH_PTYPE_ARP),
 			    ll->addr, entry->eth.addr);
 
 	return pkt;

subsys/net/l2/ethernet/ethernet.c

@@ -419,24 +419,30 @@ static enum net_verdict ethernet_send(struct net_if *iface,
 			goto setup_hdr;
 		}
 
-		arp_pkt = net_arp_prepare(pkt, &NET_IPV4_HDR(pkt)->dst, NULL);
-		if (!arp_pkt) {
-			return NET_DROP;
-		}
+		/* Trying to send ARP message so no need to setup it twice */
+		if (ntohs(NET_ETH_HDR(pkt)->type) != NET_ETH_PTYPE_ARP) {
+			arp_pkt = net_arp_prepare(pkt, &NET_IPV4_HDR(pkt)->dst,
+						  NULL);
+			if (!arp_pkt) {
+				return NET_DROP;
+			}
 
-		if (pkt != arp_pkt) {
-			NET_DBG("Sending arp pkt %p (orig %p) to iface %p",
-				arp_pkt, pkt, iface);
+			if (pkt != arp_pkt) {
+				NET_DBG("Sending arp pkt %p (orig %p) to "
+					"iface %p",
+					arp_pkt, pkt, iface);
 
-			/* Either pkt went to ARP pending queue or
-			 * there was no space in the queue anymore.
-			 */
-			net_pkt_unref(pkt);
+				/* Either pkt went to ARP pending queue or
+				 * there was no space in the queue anymore.
+				 */
+				net_pkt_unref(pkt);
 
-			pkt = arp_pkt;
-		} else {
-			NET_DBG("Found ARP entry, sending pkt %p to iface %p",
-				pkt, iface);
+				pkt = arp_pkt;
+			} else {
+				NET_DBG("Found ARP entry, sending pkt %p to "
+					"iface %p",
+					pkt, iface);
+			}
 		}
 
 		net_pkt_ll_src(pkt)->addr = (u8_t *)&NET_ETH_HDR(pkt)->src;