Implement dns cache handlers

res/res_pjsip/pjsip_resolver.c

@@ -68,8 +68,7 @@ struct host_track_entry {
 struct dns_cache_entry {
 	char *host;
 	pjsip_server_addresses addresses;
-	int ttl;
-	time_t entry_time;
+	int expiration_time;
 	AST_LIST_ENTRY(dns_cache_entry) next;
 };
 
@@ -921,6 +920,69 @@ static void sip_check_transport(pj_pool_t *pool, pjsip_transport_type_e transpor
 	}
 }
 
+static int dns_cache_get_addr(const char *host, pjsip_server_addresses *addresses)
+{
+    	struct dns_cache_entry *cache_entry = NULL;
+	int ret = -1;
+
+	if (!host || !addresses)
+		return -1;
+
+	AST_LIST_LOCK(&sip_dns_cache);
+
+	AST_LIST_TRAVERSE_SAFE_BEGIN(&sip_dns_cache, cache_entry, next) {
+		if (strcmp(host, cache_entry->host) == 0) {
+			if (cache_entry->expiration_time > time(NULL)) {
+				ast_debug(5, "cache_entry '%s': record found\n", cache_entry->host);
+				pj_memcpy(addresses, &cache_entry->addresses, sizeof(*addresses));
+				ret = 0;
+			}
+			break;
+		}
+	}
+	AST_LIST_TRAVERSE_SAFE_END;
+
+	AST_LIST_UNLOCK(&sip_dns_cache);
+
+	return ret;
+}
+
+static int dns_cache_update(const char *host, pjsip_server_addresses *addresses, int ttl)
+{
+	struct dns_cache_entry *cache_entry = NULL;
+	struct dns_cache_entry *new_cache_entry = NULL;
+	int found = 0;
+
+	if (!host || !addresses)
+		return -1;
+
+	AST_LIST_LOCK(&sip_dns_cache);
+
+	AST_LIST_TRAVERSE_SAFE_BEGIN(&sip_dns_cache, cache_entry, next) {
+		if (cache_entry && strcmp(host, cache_entry->host) == 0) {
+			ast_debug(5, "cache_entry '%s' recond found: updating\n", cache_entry->host);
+			pj_memcpy(&cache_entry->addresses, addresses, sizeof(*addresses));
+			cache_entry->expiration_time = time(NULL) + ttl;
+			found = 1;
+			break;
+		}
+	}
+	AST_LIST_TRAVERSE_SAFE_END;
+
+	if (!found) {
+		new_cache_entry = ast_calloc(1, sizeof(*new_cache_entry));
+		new_cache_entry->host = strdup(host);
+		pj_memcpy(&new_cache_entry->addresses, addresses, sizeof(*addresses));
+		new_cache_entry->expiration_time = time(NULL) + ttl;
+		AST_LIST_INSERT_HEAD(&sip_dns_cache, new_cache_entry, next);
+		ast_debug(5, "cache_entry '%s': record added\n", new_cache_entry->host);
+	}
+
+	AST_LIST_UNLOCK(&sip_dns_cache);
+
+	return 0;
+}
+
 /* External API to set DNS cache function pointers */
 void pjsip_resolver_set_dns_cache(dns_cache_get_addr_t get_addr, dns_cache_update_t update_cache)
 {
@@ -978,6 +1040,7 @@ void ast_sip_initialize_resolver(void)
 {
 	/* Replace the existing PJSIP resolver with our own implementation */
 	ast_sip_push_task_wait_servant(NULL, sip_replace_resolver, NULL);
+	pjsip_resolver_set_dns_cache(dns_cache_get_addr, dns_cache_update);
 }
 
 #else