samples: net: dns: Add mDNS client support to DNS resolver sample

The DNS resolver example enables mDNS client support and then
queries zephyr.local hostname. The net-tools project has example
avahi-daemon script that will response these .local queries and
can be used in testing.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

samples/net/dns_resolve/README.rst

@@ -13,6 +13,10 @@ If a CNAME is received, the DNS resolver will create another DNS query.
 The number of additional queries is controlled by the
 DNS_RESOLVER_ADDITIONAL_QUERIES Kconfig variable.
 
+The multicast DNS (mDNS) client resolver support can be enabled by setting
+CONFIG_MDNS_RESOLVER Kconfig variable.
+See https://tools.ietf.org/html/rfc6762 for more details about mDNS.
+
 For more information about DNS configuration variables, see:
 :file:`subsys/net/lib/dns/Kconfig`. The DNS resolver API can be found at
 :file:`include/net/dns_resolve.h`. The sample code can be found at:
@@ -34,28 +38,6 @@ Requirements
     dnsmasq -v
     Dnsmasq version 2.76  Copyright (c) 2000-2016 Simon Kelley
 
-
-
-Wiring
-******
-
-The ENC28J60 module is an Ethernet device with SPI interface.
-The following pins must be connected from the ENC28J60 device to the
-Arduino 101 board:
-
-===========	===================================
-Arduino 101	ENC28J60 (pin numbers on the board)
-===========	===================================
-D13		SCK  (1)
-D12		SO   (3)
-D11		SI   (2)
-D10		CS   (7)
-D04		INT  (5)
-3.3V		VCC  (10)
-GDN		GND  (9)
-===========	===================================
-
-
 Building and Running
 ********************
 
@@ -90,9 +72,7 @@ Open a terminal window and type:
 .. code-block:: console
 
     $ cd net-tools
-    $ ./dnsmasq.sh
+    $ sudo ./dnsmasq.sh
-
-('su' or 'sudo' may be required.)
 
 The default project configurations settings for this sample uses the public
 Google DNS servers.  In order to use the local dnsmasq server, please edit
@@ -122,9 +102,15 @@ Open a terminal window and type:
 
     $ killall -s KILL dnsmasq
 
-
 Try to launch the dnsmasq application again.
 
+For testing mDNS, use Avahi script in net-tools project:
+
+.. code-block:: console
+
+    $ cd net-tools
+    $ ./avahi-daemon.sh
+
 QEMU x86
 ========
 
@@ -186,3 +172,19 @@ Open a terminal window and type:
 Use 'dmesg' to find the right USB device.
 
 Once the binary is loaded into the Arduino 101 board, press the RESET button.
+
+The ENC28J60 module is an Ethernet device with SPI interface.
+The following pins must be connected from the ENC28J60 device to the
+Arduino 101 board:
+
+===========    ===================================
+Arduino 101    ENC28J60 (pin numbers on the board)
+===========    ===================================
+D13            SCK  (1)
+D12            SO   (3)
+D11            SI   (2)
+D10            CS   (7)
+D04            INT  (5)
+3.3V           VCC  (10)
+GDN            GND  (9)
+===========    ===================================

samples/net/dns_resolve/prj.conf

@@ -3,19 +3,19 @@ CONFIG_NET_UDP=y
 CONFIG_RANDOM_GENERATOR=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 CONFIG_INIT_STACKS=y
-CONFIG_NET_PKT_RX_COUNT=4
+CONFIG_NET_PKT_RX_COUNT=10
-CONFIG_NET_PKT_TX_COUNT=4
+CONFIG_NET_PKT_TX_COUNT=10
-CONFIG_NET_BUF_RX_COUNT=14
+CONFIG_NET_BUF_RX_COUNT=10
-CONFIG_NET_BUF_TX_COUNT=14
+CONFIG_NET_BUF_TX_COUNT=10
 
 CONFIG_NET_IF_UNICAST_IPV6_ADDR_COUNT=3
 CONFIG_NET_IF_MCAST_IPV6_ADDR_COUNT=5
 
 CONFIG_NET_LOG=y
 CONFIG_SYS_LOG=y
-CONFIG_SYS_LOG_NET_LEVEL=4
+CONFIG_SYS_LOG_NET_LEVEL=2
 CONFIG_SYS_LOG_SHOW_COLOR=y
-#CONFIG_NET_DEBUG_NET_PKT=y
+CONFIG_NET_DEBUG_NET_PKT=y
 CONFIG_NET_DEBUG_DNS_RESOLVE=y
 #CONFIG_NET_DEBUG_CONTEXT=y
 #CONFIG_NET_DEBUG_CORE=y
@@ -24,27 +24,35 @@ CONFIG_NET_DEBUG_DNS_RESOLVE=y
 #CONFIG_NET_DEBUG_IPV6=y
 #CONFIG_NET_DEBUG_UDP=y
 #CONFIG_NET_DEBUG_DHCPV4=y
-#CONFIG_SLIP_DEBUG=y
+#CONFIG_NET_DEBUG_L2_ETHERNET=y
 
-CONFIG_NET_IPV4=y
 CONFIG_NET_IPV6=y
+CONFIG_NET_IPV4=y
+CONFIG_NET_DHCPV4=n
 
 # Enable the DNS resolver
 CONFIG_DNS_RESOLVER=y
 # Enable additional buffers
-CONFIG_DNS_RESOLVER_ADDITIONAL_BUF_CTR=2
+CONFIG_DNS_RESOLVER_ADDITIONAL_BUF_CTR=5
 # Enable additional queries
 CONFIG_DNS_RESOLVER_ADDITIONAL_QUERIES=2
+# Enable mDNS support
+CONFIG_MDNS_RESOLVER=y
 
 CONFIG_DNS_RESOLVER_MAX_SERVERS=2
 CONFIG_DNS_SERVER_IP_ADDRESSES=y
-CONFIG_DNS_NUM_CONCUR_QUERIES=2
+CONFIG_DNS_NUM_CONCUR_QUERIES=5
+
+# Use local dnsmasq server for testing
+CONFIG_DNS_SERVER1="[2001:db8::2]:15353"
+CONFIG_DNS_SERVER2="192.0.2.2:15353"
 
 # Google DNS IPv4 and IPv6 servers
-CONFIG_DNS_SERVER1="8.8.8.8"
+#CONFIG_DNS_SERVER1="8.8.8.8"
-CONFIG_DNS_SERVER2="2001:4860:4860::8888"
+#CONFIG_DNS_SERVER2="2001:4860:4860::8888"
 
-CONFIG_NET_DHCPV4=y
+# Router is needed when resolving using external DNS servers
+CONFIG_NET_APP_NEED_IPV6_ROUTER=n
 
 CONFIG_NET_MGMT=y
 CONFIG_NET_MGMT_EVENT=y
@@ -52,7 +60,11 @@ CONFIG_NET_MGMT_EVENT=y
 CONFIG_NET_SHELL=y
 
 CONFIG_NET_APP_SETTINGS=y
+CONFIG_NET_APP_NEED_IPV6=y
+CONFIG_NET_APP_NEED_IPV4=y
 CONFIG_NET_APP_MY_IPV6_ADDR="2001:db8::1"
 CONFIG_NET_APP_PEER_IPV6_ADDR="2001:db8::2"
 CONFIG_NET_APP_MY_IPV4_ADDR="192.0.2.1"
 CONFIG_NET_APP_PEER_IPV4_ADDR="192.0.2.2"
+
+CONFIG_MAIN_STACK_SIZE=1504

samples/net/dns_resolve/src/main.c

@@ -20,7 +20,18 @@
 #include <net/net_mgmt.h>
 #include <net/dns_resolve.h>
 
-#define DNS_TIMEOUT 2000 /* ms */
+#if defined(CONFIG_MDNS_RESOLVER)
+#if defined(CONFIG_NET_IPV4)
+static struct k_delayed_work mdns_ipv4_timer;
+static void do_mdns_ipv4_lookup(struct k_work *work);
+#endif
+#if defined(CONFIG_NET_IPV6)
+static struct k_delayed_work mdns_ipv6_timer;
+static void do_mdns_ipv6_lookup(struct k_work *work);
+#endif
+#endif
+
+#define DNS_TIMEOUT K_SECONDS(2)
 
 void dns_result_cb(enum dns_resolve_status status,
 		   struct dns_addrinfo *info,
@@ -54,6 +65,64 @@ void dns_result_cb(enum dns_resolve_status status,
 		return;
 	}
 
+	if (info->ai_family == AF_INET) {
+		hr_family = "IPv4";
+		addr = &net_sin(&info->ai_addr)->sin_addr;
+
+#if defined(CONFIG_MDNS_RESOLVER) && defined(CONFIG_NET_IPV4)
+		k_delayed_work_init(&mdns_ipv4_timer, do_mdns_ipv4_lookup);
+		k_delayed_work_submit(&mdns_ipv4_timer, 0);
+#endif
+	} else if (info->ai_family == AF_INET6) {
+		hr_family = "IPv6";
+		addr = &net_sin6(&info->ai_addr)->sin6_addr;
+
+#if defined(CONFIG_MDNS_RESOLVER) && defined(CONFIG_NET_IPV6)
+		k_delayed_work_init(&mdns_ipv6_timer, do_mdns_ipv6_lookup);
+		k_delayed_work_submit(&mdns_ipv6_timer, 0);
+#endif
+	} else {
+		NET_ERR("Invalid IP address family %d", info->ai_family);
+		return;
+	}
+
+	NET_INFO("%s %s address: %s", user_data ? (char *)user_data : "<null>", hr_family,
+		 net_addr_ntop(info->ai_family, addr,
+			       hr_addr, sizeof(hr_addr)));
+}
+
+void mdns_result_cb(enum dns_resolve_status status,
+		    struct dns_addrinfo *info,
+		    void *user_data)
+{
+	char hr_addr[NET_IPV6_ADDR_LEN];
+	char *hr_family;
+	void *addr;
+
+	switch (status) {
+	case DNS_EAI_CANCELED:
+		NET_INFO("DNS query was canceled");
+		return;
+	case DNS_EAI_FAIL:
+		NET_INFO("DNS resolve failed");
+		return;
+	case DNS_EAI_NODATA:
+		NET_INFO("Cannot resolve address");
+		return;
+	case DNS_EAI_ALLDONE:
+		NET_INFO("DNS resolving finished");
+		return;
+	case DNS_EAI_INPROGRESS:
+		break;
+	default:
+		NET_INFO("DNS resolving error (%d)", status);
+		return;
+	}
+
+	if (!info) {
+		return;
+	}
+
 	if (info->ai_family == AF_INET) {
 		hr_family = "IPv4";
 		addr = &net_sin(&info->ai_addr)->sin_addr;
@@ -65,7 +134,7 @@ void dns_result_cb(enum dns_resolve_status status,
 		return;
 	}
 
-	NET_INFO("%s address: %s", hr_family,
+	NET_INFO("%s %s address: %s", user_data ? (char *)user_data : "<null>", hr_family,
 		 net_addr_ntop(info->ai_family, addr,
 			       hr_addr, sizeof(hr_addr)));
 }
@@ -76,14 +145,15 @@ static struct k_delayed_work ipv4_timer;
 
 static void do_ipv4_lookup(struct k_work *work)
 {
+	static const char *query = "www.zephyrproject.org";
 	u16_t dns_id;
 	int ret;
 
-	ret = dns_get_addr_info("www.zephyrproject.org",
+	ret = dns_get_addr_info(query,
 				DNS_QUERY_TYPE_A,
 				&dns_id,
 				dns_result_cb,
-				NULL,
+				(void *)query,
 				DNS_TIMEOUT);
 	if (ret < 0) {
 		NET_ERR("Cannot resolve IPv4 address (%d)", ret);
@@ -147,6 +217,32 @@ static void setup_dhcpv4(struct net_if *iface)
 #define setup_dhcpv4(...)
 #endif /* CONFIG_NET_DHCPV4 */
 
+#if defined(CONFIG_NET_IPV4) || defined(CONFIG_NET_DHCPV4)
+#if defined(CONFIG_MDNS_RESOLVER)
+static void do_mdns_ipv4_lookup(struct k_work *work)
+{
+	static const char *query = "zephyr.local";
+	u16_t dns_id;
+	int ret;
+
+	NET_DBG("Doing mDNS IPv4 query");
+
+	ret = dns_get_addr_info(query,
+				DNS_QUERY_TYPE_A,
+				&dns_id,
+				mdns_result_cb,
+				(void *)query,
+				DNS_TIMEOUT);
+	if (ret < 0) {
+		NET_ERR("Cannot resolve mDNS IPv4 address (%d)", ret);
+		return;
+	}
+
+	NET_DBG("mDNS id %u", dns_id);
+}
+#endif
+#endif
+
 #if defined(CONFIG_NET_IPV4) && !defined(CONFIG_NET_DHCPV4)
 
 #if !defined(CONFIG_NET_APP_MY_IPV4_ADDR)
@@ -155,6 +251,7 @@ static void setup_dhcpv4(struct net_if *iface)
 
 static void setup_ipv4(struct net_if *iface)
 {
+	static const char *query = "www.zephyrproject.org";
 	char hr_addr[NET_IPV4_ADDR_LEN];
 	struct in_addr addr;
 	u16_t dns_id;
@@ -170,11 +267,11 @@ static void setup_ipv4(struct net_if *iface)
 	NET_INFO("IPv4 address: %s",
 		 net_addr_ntop(AF_INET, &addr, hr_addr, NET_IPV4_ADDR_LEN));
 
-	ret = dns_get_addr_info("www.zephyrproject.org",
+	ret = dns_get_addr_info(query,
 				DNS_QUERY_TYPE_A,
 				&dns_id,
 				dns_result_cb,
-				NULL,
+				(void *)query,
 				DNS_TIMEOUT);
 	if (ret < 0) {
 		NET_ERR("Cannot resolve IPv4 address (%d)", ret);
@@ -194,19 +291,17 @@ static void setup_ipv4(struct net_if *iface)
 #error "You need to define an IPv6 address!"
 #endif
 
-static struct net_mgmt_event_callback mgmt6_cb;
+static void do_ipv6_lookup(void)
-static struct k_delayed_work ipv6_timer;
-
-static void do_ipv6_lookup(struct k_work *work)
 {
+	static const char *query = "www.zephyrproject.org";
 	u16_t dns_id;
 	int ret;
 
-	ret = dns_get_addr_info("www.zephyrproject.org",
+	ret = dns_get_addr_info(query,
 				DNS_QUERY_TYPE_AAAA,
 				&dns_id,
 				dns_result_cb,
-				NULL,
+				(void *)query,
 				DNS_TIMEOUT);
 	if (ret < 0) {
 		NET_ERR("Cannot resolve IPv6 address (%d)", ret);
@@ -216,48 +311,34 @@ static void do_ipv6_lookup(struct k_work *work)
 	NET_DBG("DNS id %u", dns_id);
 }
 
-/* DNS query will most probably fail if we do not have a default
- * router configured because typically the DNS server is outside of local
- * network. So wait for that before continuing.
- */
-static void ipv6_router_add_handler(struct net_mgmt_event_callback *cb,
-				    u32_t mgmt_event,
-				    struct net_if *iface)
-{
-	if (mgmt_event != NET_EVENT_IPV6_ROUTER_ADD) {
-		return;
-	}
-
-	/* We cannot run DNS lookup directly from this thread as the
-	 * management event thread stack is very small by default.
-	 * So run it from work queue instead.
-	 */
-	k_delayed_work_init(&ipv6_timer, do_ipv6_lookup);
-	k_delayed_work_submit(&ipv6_timer, 0);
-}
-
 static void setup_ipv6(struct net_if *iface)
 {
-	char hr_addr[NET_IPV6_ADDR_LEN];
+	do_ipv6_lookup();
-	struct in6_addr addr;
+}
 
-	if (net_addr_pton(AF_INET6, CONFIG_NET_APP_MY_IPV6_ADDR, &addr)) {
+#if defined(CONFIG_MDNS_RESOLVER)
-		NET_ERR("Invalid address: %s", CONFIG_NET_APP_MY_IPV6_ADDR);
+static void do_mdns_ipv6_lookup(struct k_work *work)
+{
+	static const char *query = "zephyr.local";
+	u16_t dns_id;
+	int ret;
+
+	NET_DBG("Doing mDNS IPv6 query");
+
+	ret = dns_get_addr_info(query,
+				DNS_QUERY_TYPE_AAAA,
+				&dns_id,
+				mdns_result_cb,
+				(void *)query,
+				DNS_TIMEOUT);
+	if (ret < 0) {
+		NET_ERR("Cannot resolve mDNS IPv6 address (%d)", ret);
 		return;
 	}
 
-	net_mgmt_init_event_callback(&mgmt6_cb, ipv6_router_add_handler,
+	NET_DBG("mDNS id %u", dns_id);
-				     NET_EVENT_IPV6_ROUTER_ADD);
-	net_mgmt_add_event_callback(&mgmt6_cb);
-
-	net_if_ipv6_addr_add(iface, &addr, NET_ADDR_MANUAL, 0);
-
-	NET_INFO("IPv6 address: %s",
-		 net_addr_ntop(AF_INET6, &addr, hr_addr, NET_IPV6_ADDR_LEN));
-
-	NET_INFO("Waiting for IPv6 default router notification "
-		 "before issuing DNS query");
 }
+#endif
 
 #else
 #define setup_ipv6(...)