Reduce periodic DNS traces

Only trace when there is change in the DNS status to prevent periodic
DNS Traces

Added Validation to DNS server address storage

Author: Mika Tervonen

source/6LoWPAN/ws/ws_bbr_api.c

@@ -517,7 +517,6 @@ static void ws_bbr_dhcp_server_dns_info_update(protocol_interface_info_entry_t *
         for (int n = 0; n < MAX_DNS_RESOLUTIONS; n++) {
             if (pre_resolved_dns_queries[n].domain_name != NULL) {
                 ptr = net_dns_option_vendor_option_data_dns_query_write(ptr, pre_resolved_dns_queries[n].address, pre_resolved_dns_queries[n].domain_name);
-                tr_info("set DNS query result for %s, addr: %s", pre_resolved_dns_queries[n].domain_name, tr_ipv6(pre_resolved_dns_queries[n].address));
             }
         }
     }
@@ -1459,6 +1458,7 @@ int ws_bbr_dns_query_result_set(int8_t interface_id, const uint8_t address[16],
             if (address) {
                 // Update address
                 memcpy(pre_resolved_dns_queries[n].address, address, 16);
+                tr_info("Update DNS query result for %s, addr: %s", pre_resolved_dns_queries[n].domain_name, tr_ipv6(pre_resolved_dns_queries[n].address));
             } else {
                 // delete entry
                 memset(pre_resolved_dns_queries[n].address, 0, 16);
@@ -1481,6 +1481,7 @@ int ws_bbr_dns_query_result_set(int8_t interface_id, const uint8_t address[16],
                 }
                 memcpy(pre_resolved_dns_queries[n].address, address, 16);
                 strcpy(pre_resolved_dns_queries[n].domain_name, domain_name_ptr);
+                tr_info("set DNS query result for %s, addr: %s", pre_resolved_dns_queries[n].domain_name, tr_ipv6(pre_resolved_dns_queries[n].address));
                 goto update_information;
             }
         }

source/6LoWPAN/ws/ws_bootstrap.c

@@ -1014,7 +1014,8 @@ static void ws_bootstrap_dhcp_info_notify_cb(int8_t interface, dhcp_option_notif
             break;
 
         case DHCPV6_OPTION_DNS_SERVERS:
-            while (options->option.generic.data_length) {
+            while (options->option.generic.data_length && options->option.generic.data_length >= 16 && options->option.generic.data_length % 16 == 0) {
+                // Validate payload to have full 16 byte length addresses without any extra bytes
                 net_dns_server_address_set(interface, server_ll64, options->option.generic.data, server_info->life_time);
                 options->option.generic.data_length -= 16;
                 options->option.generic.data += 16;

source/libNET/src/net_dns.c

@@ -112,10 +112,11 @@ int8_t net_dns_server_address_set(int8_t interface_id, const uint8_t address[16]
 
     if (!info_ptr) {
         info_ptr = dns_server_info_create(interface_id, address);
+        // Trace only when new entry is created
+        tr_info("DNS Server: %s from: %s Lifetime: %lu", trace_ipv6(dns_server_address), trace_ipv6(info_ptr->address), (unsigned long) lifetime);
     }
     info_ptr->lifetime = lifetime;
     memcpy(info_ptr->dns_server_address, dns_server_address, 16);
-    tr_info("DNS Server: %s from: %s Lifetime: %lu", trace_ipv6(info_ptr->dns_server_address), trace_ipv6(info_ptr->address), (unsigned long) info_ptr->lifetime);
     return 0;
 }
 
@@ -148,22 +149,22 @@ int8_t net_dns_server_search_list_set(int8_t interface_id, const uint8_t address
     if (info_ptr->dns_search_list_ptr && info_ptr->dns_search_list_len != dns_search_list_len) {
         ns_dyn_mem_free(info_ptr->dns_search_list_ptr);
         info_ptr->dns_search_list_ptr = NULL;
+        info_ptr->dns_search_list_len = 0;
     }
 
     if (dns_search_list_len) {
         if (!info_ptr->dns_search_list_ptr) {
             info_ptr->dns_search_list_ptr = ns_dyn_mem_alloc(dns_search_list_len);
+
+            tr_info("DNS Search List: %s Lifetime: %lu", trace_array(dns_search_list_ptr, dns_search_list_len), (unsigned long) info_ptr->lifetime);
         }
 
         if (!info_ptr->dns_search_list_ptr) {
             return -2;
         }
         memcpy(info_ptr->dns_search_list_ptr, dns_search_list_ptr, dns_search_list_len);
+        info_ptr->dns_search_list_len = dns_search_list_len;
     }
-
-    info_ptr->dns_search_list_len = dns_search_list_len;
-    tr_info("DNS Search List: %s Lifetime: %lu", trace_array(info_ptr->dns_search_list_ptr, info_ptr->dns_search_list_len), (unsigned long) info_ptr->lifetime);
-
     return 0;
 }