gcoap_dns: implement Max-Age-based TTL calculation

RIOT-OS · Aug 11, 2022 · 6f18132 · 6f18132
1 parent a93ba1e
commit 6f18132
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/sys/net/application_layer/gcoap/dns.c b/sys/net/application_layer/gcoap/dns.c
@@ -740,11 +740,17 @@ static void _resp_handler(const gcoap_request_memo_t *memo, coap_pkt_t *pdu,
     switch (coap_get_content_type(pdu)) {
         case COAP_FORMAT_DNS_MESSAGE:
         case COAP_FORMAT_NONE: {
-            uint32_t ttl;
+            uint32_t ttl = 0;
 
             context->res = dns_msg_parse_reply(data, data_len, family,
                                                context->addr_out, &ttl);
-            if (context->res > 0) {
+            if (IS_USED(MODULE_DNS_CACHE) && (context->res > 0)) {
+                uint32_t max_age;
+
+                if (coap_opt_get_uint(pdu, COAP_OPT_MAX_AGE, &max_age) < 0) {
+                    max_age = 60;
+                }
+                ttl += max_age;
                 dns_cache_add(_domain_name_from_ctx(context), context->addr_out, context->res, ttl);
             }
             else if (ENABLE_DEBUG && (context->res < 0)) {