Omit NA sending in ARO success cases. Use ACK instead. (ARMmbed#1587)

When "omit_aro_success" - flag is set, success response is not send to request.
MAC ack is used to indicate success address registration.

Author: Tero Heinonen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -72,11 +72,16 @@ static void ws_bootstrap_address_registration_ns_send(struct protocol_interface_
     aro_t aro;
     buffer_t *buf;
 
+    tr_debug("Send ARO");
+
     aro.status = ARO_SUCCESS;
     aro.present = true;
     aro.lifetime = addr->preferred_lifetime;
     memcpy(aro.eui64, interface->mac, 8);
 
+    /* Fill address to be registered */
+    memcpy(&interface->if_6lowpan_dad_process.address, addr->address, 16);
+
     ns_list_foreach(struct rpl_instance, instance, &interface->rpl_domain->instances) {
         const uint8_t *preferred_parent = rpl_control_preferred_parent_addr(instance, false);
         if (preferred_parent) {
@@ -153,6 +158,8 @@ static int8_t ws_bootsrap_event_trig(ws_bootsrap_event_type_e event_type, int8_t
     }
     /* Disable SLLAO send/mandatory receive with the ARO */
     cur->ipv6_neighbour_cache.use_eui64_as_slla_in_aro = true;
+    /* Omit sending of NA if ARO SUCCESS */
+    cur->ipv6_neighbour_cache.omit_aro_success = true;
 
     ws_bootstrap_event_discovery_start(cur);
 

source/Common_Protocols/icmpv6.c

@@ -1214,6 +1214,25 @@ uint8_t *icmpv6_write_mtu_option(uint32_t mtu, uint8_t *dptr)
     return dptr;
 }
 
+static void icmpv6_ns_ack_cb(struct buffer *buf, uint8_t status)
+{
+    (void) buf;
+
+    if (status == SOCKET_TX_DONE) {
+        tr_debug("NS ARO ack received %s", trace_ipv6(buf->interface->if_6lowpan_dad_process.address));
+
+        if_address_entry_t *addr_entry = addr_get_entry(buf->interface, buf->interface->if_6lowpan_dad_process.address);
+        if (!addr_entry) {
+            return;
+        }
+        /* State_timer is 1/10 s. Set renewal to 75-85% of lifetime */
+        addr_entry->state_timer = (addr_entry->preferred_lifetime * randLIB_get_random_in_range(75, 85) / 10);
+    } else {
+        // todo: What to do when address registration fails?
+        tr_debug("NS ARO send failed");
+    }
+}
+
 buffer_t *icmpv6_build_ns(protocol_interface_info_entry_t *cur, const uint8_t target_addr[16], const uint8_t *prompting_src_addr, bool unicast, bool unspecified_source, const aro_t *aro)
 {
     if (!cur || addr_is_ipv6_multicast(target_addr)) {
@@ -1286,6 +1305,11 @@ buffer_t *icmpv6_build_ns(protocol_interface_info_entry_t *cur, const uint8_t ta
         if (!cur->ipv6_neighbour_cache.use_eui64_as_slla_in_aro) {
             ptr = icmpv6_write_icmp_lla(cur, ptr, ICMPV6_OPT_SRC_LL_ADDR, aro, buf->src_sa.address);
         }
+        /* If ARO Success sending is omitted, MAC ACK is used instead */
+        /* Setting callback for receiving ACK from adaptation layer */
+        if (aro && cur->ipv6_neighbour_cache.omit_aro_success) {
+            buf->ack_receive_cb = icmpv6_ns_ack_cb;
+        }
     }
     buf->src_sa.addr_type = ADDR_IPV6;
 
@@ -1419,6 +1443,12 @@ buffer_t *icmpv6_build_na(protocol_interface_info_entry_t *cur, bool solicited,
 
     tr_debug("Build NA");
 
+    /* Check if ARO status == success, then sending can be omitted with flag */
+    if (aro && cur->ipv6_neighbour_cache.omit_aro_success && aro->status == ARO_SUCCESS) {
+        tr_debug("Omit success reply");
+        return NULL;
+    }
+
     buffer_t *buf = buffer_get(8 + 16 + 16 + 16); /* fixed, target addr, target ll addr, aro */
     if (!buf) {
         return NULL;

source/Core/include/ns_buffer.h

@@ -228,6 +228,7 @@ typedef struct buffer {
     uint8_t             trickle_data_field[4];
     buffer_options_t    options;                /*!< Additional signal info etc */
     buffer_routing_info_t *route;               /* A pointer last to try to get neat alignment for data */
+    void (*ack_receive_cb)(struct buffer *buffer_ptr, uint8_t status); /*!< ACK receive callback. If set, will be called when TX is done */
     uint8_t             buf[];                  /*!< Trailing buffer data */
  } buffer_t;
 

source/Core/ns_socket.c

@@ -1396,6 +1396,10 @@ buffer_t *socket_tx_buffer_event(buffer_t *buf, uint8_t status)
      * and we mapped straight to MAC address).
      */
 
+    if (buf->ack_receive_cb) {
+        buf->ack_receive_cb(buf, status);
+    }
+
     /* Suppress events once socket orphaned */
     if (!buf->socket || (buf->socket->flags & (SOCKET_FLAG_PENDING|SOCKET_FLAG_CLOSED))) {
         return buf;

source/ipv6_stack/ipv6_routing_table.h

@@ -120,6 +120,7 @@ typedef struct ipv6_neighbour_cache {
     bool                                    recv_ns_aro : 1;
     bool                                    recv_na_aro : 1;
     bool                                    use_eui64_as_slla_in_aro : 1;
+    bool                                    omit_aro_success : 1;
     int8_t                                  interface_id;
     uint8_t                                 max_ll_len;
     uint8_t                                 gc_timer;