tests: net: dns: Add tests for joining mDNS multicast group

Make sure that if mDNS resolver is enabled, we join the mDNS
multicast group so that query responses can be received.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>

Author: jukkar

tests/net/lib/dns_resolve/src/main.c

@@ -762,4 +762,55 @@ ZTEST(dns_resolve, test_dns_query_ipv6_numeric)
 	}
 }
 
+#define MDNS_IPV4_ADDR "224.0.0.251:5353"
+#define MDNS_IPV6_ADDR "[ff02::fb]:5353"
+
+ZTEST(dns_resolve, test_mdns_ipv4_igmp_group)
+{
+	struct net_if_mcast_addr *maddr;
+	struct sockaddr_in addr4;
+	bool st;
+
+	/* Skip this test if mDNS responder is enabled because it will join
+	 * multicast group automatically.
+	 */
+	Z_TEST_SKIP_IFDEF(CONFIG_MDNS_RESPONDER);
+	Z_TEST_SKIP_IFNDEF(CONFIG_NET_IPV4);
+	Z_TEST_SKIP_IFNDEF(CONFIG_NET_IPV4_IGMP);
+
+	st = net_ipaddr_parse(MDNS_IPV4_ADDR, sizeof(MDNS_IPV4_ADDR) - 1,
+			      (struct sockaddr *)&addr4);
+	zassert_true(st, "Cannot parse IPv4 address");
+
+	maddr = net_if_ipv4_maddr_lookup(&addr4.sin_addr, NULL);
+	zassert_not_null(maddr, "IPv4 mDNS address not found");
+
+	st = net_if_ipv4_maddr_is_joined(maddr);
+	zassert_true(st, "IPv4 mDNS group not joined");
+}
+
+ZTEST(dns_resolve, test_mdns_ipv6_mld_group)
+{
+	struct net_if_mcast_addr *maddr;
+	struct sockaddr_in6 addr6;
+	bool st;
+
+	/* Skip this test if mDNS responder is enabled because it will join
+	 * multicast group automatically.
+	 */
+	Z_TEST_SKIP_IFDEF(CONFIG_MDNS_RESPONDER);
+	Z_TEST_SKIP_IFNDEF(CONFIG_NET_IPV6);
+	Z_TEST_SKIP_IFNDEF(CONFIG_NET_IPV6_MLD);
+
+	st = net_ipaddr_parse(MDNS_IPV6_ADDR, sizeof(MDNS_IPV6_ADDR) - 1,
+			      (struct sockaddr *)&addr6);
+	zassert_true(st, "Cannot parse IPv6 address");
+
+	maddr = net_if_ipv6_maddr_lookup(&addr6.sin6_addr, NULL);
+	zassert_not_null(maddr, "IPv6 mDNS address not found");
+
+	st = net_if_ipv6_maddr_is_joined(maddr);
+	zassert_true(st, "IPv6 mDNS group not joined");
+}
+
 ZTEST_SUITE(dns_resolve, NULL, test_init, NULL, NULL, NULL);

tests/net/lib/dns_resolve/testcase.yaml

@@ -15,3 +15,9 @@ tests:
   net.dns.resolve.no_ipv6:
     extra_args: CONF_FILE=prj-no-ipv6.conf
     min_ram: 16
+  net.mdns.resolve:
+    extra_configs:
+      - CONFIG_MDNS_RESOLVER=y
+      - CONFIG_MDNS_RESPONDER=n
+      - CONFIG_NET_IPV6_MLD=y
+      - CONFIG_NET_IPV4_IGMP=y