net: lldp: Move optional End TLV to send function

In a case we have optional TLVs we need to send End TLV in the very
end.

Signed-off-by: Andrei Emeltchenko <[email protected]>

Author: finikorg

include/net/lldp.h

@@ -141,11 +141,6 @@ struct net_lldpdu {
 	struct net_lldp_chassis_tlv chassis_id;	/* Mandatory TLV */
 	struct net_lldp_port_tlv port_id;	/* Mandatory TLV */
 	struct net_lldp_time_to_live_tlv ttl;	/* Mandatory TLV */
-
-#if defined(CONFIG_NET_LLDP_END_LLDPDU_TLV_ENABLED)
-	/** Optional End of LLDPDU TLV. Must be set to 0x0000 always. */
-	const uint16_t end_lldpdu_tlv;
-#endif /* CONFIG_NET_LLDP_END_LLDPDU_TLV_ENABLED */
 } __packed;
 
 /**

subsys/net/l2/ethernet/lldp/lldp.c

@@ -127,6 +127,17 @@ static int lldp_send(struct ethernet_lldp *lldp)
 		}
 	}
 
+	if (IS_ENABLED(CONFIG_NET_LLDP_END_LLDPDU_TLV_ENABLED)) {
+		u16_t tlv_end = htons(NET_LLDP_END_LLDPDU_VALUE);
+
+		if (!net_pkt_write_new(pkt, (u8_t *)&tlv_end,
+				       sizeof(tlv_end))) {
+			net_pkt_unref(pkt);
+			ret = -ENOMEM;
+			goto out;
+		}
+	}
+
 	net_pkt_lladdr_src(pkt)->addr = net_if_get_link_addr(lldp->iface)->addr;
 	net_pkt_lladdr_src(pkt)->len = sizeof(struct net_eth_addr);
 	net_pkt_lladdr_dst(pkt)->addr = (u8_t *)lldp_multicast_eth_addr.addr;