net: dns: Do not resolve IPv6 address if IPv6 is disabled

If IPv6 is disabled, then it is useless to try to resolve
IPv6 address because "struct sockaddr" does not have enough
space to store IPv6 address.

Fixes #1487

Signed-off-by: Jukka Rissanen <[email protected]>

Author: jukkar

subsys/net/lib/dns/resolve.c

@@ -287,11 +287,20 @@ static int dns_read(struct dns_resolve_context *ctx,
 		info->ai_addr.sa_family = AF_INET;
 		info->ai_addrlen = sizeof(struct sockaddr_in);
 	} else if (ctx->queries[query_idx].query_type == DNS_QUERY_TYPE_AAAA) {
+		/* We cannot resolve IPv6 address if IPv6 is disabled. The reason
+		 * being that "struct sockaddr" does not have enough space for
+		 * IPv6 address in that case.
+		 */
+#if defined(CONFIG_NET_IPV6)
 		address_size = DNS_IPV6_LEN;
 		addr = (u8_t *)&net_sin6(&info->ai_addr)->sin6_addr;
 		info->ai_family = AF_INET6;
 		info->ai_addr.sa_family = AF_INET6;
 		info->ai_addrlen = sizeof(struct sockaddr_in6);
+#else
+		ret = DNS_EAI_FAMILY;
+		goto quit;
+#endif
 	} else {
 		ret = DNS_EAI_FAMILY;
 		goto quit;
@@ -608,10 +617,10 @@ int dns_resolve_name(struct dns_resolve_context *ctx,
 		     void *user_data,
 		     s32_t timeout)
 {
-	struct net_buf *dns_data;
+	struct net_buf *dns_data = NULL;
 	struct net_buf *dns_qname = NULL;
 	struct sockaddr addr;
-	int ret, i, j = 0;
+	int ret, i = -1, j = 0;
 	int failure = 0;
 
 	if (!ctx || !ctx->is_used || !query || !cb) {
@@ -638,11 +647,16 @@ int dns_resolve_name(struct dns_resolve_context *ctx,
 			info.ai_addr.sa_family = AF_INET;
 			info.ai_addrlen = sizeof(struct sockaddr_in);
 		} else if (type == DNS_QUERY_TYPE_AAAA) {
+#if defined(CONFIG_NET_IPV6)
 			memcpy(net_sin6(&info.ai_addr), net_sin6(&addr),
 			       sizeof(struct sockaddr_in6));
 			info.ai_family = AF_INET6;
 			info.ai_addr.sa_family = AF_INET6;
 			info.ai_addrlen = sizeof(struct sockaddr_in6);
+#else
+			ret = -EAFNOSUPPORT;
+			goto quit;
+#endif
 		} else {
 			goto try_resolve;
 		}
@@ -729,11 +743,14 @@ int dns_resolve_name(struct dns_resolve_context *ctx,
 
 quit:
 	if (ret < 0) {
-		if (k_delayed_work_remaining_get(&ctx->queries[i].timer) > 0) {
-			k_delayed_work_cancel(&ctx->queries[i].timer);
-		}
+		if (i >= 0) {
+			if (k_delayed_work_remaining_get(
+				    &ctx->queries[i].timer) > 0) {
+				k_delayed_work_cancel(&ctx->queries[i].timer);
+			}
 
-		ctx->queries[i].cb = NULL;
+			ctx->queries[i].cb = NULL;
+		}
 
 		if (dns_id) {
 			*dns_id = 0;

tests/net/lib/dns_resolve/prj-no-ipv6.conf

@@ -0,0 +1,31 @@
+CONFIG_NETWORKING=y
+CONFIG_NET_TEST=y
+CONFIG_RANDOM_GENERATOR=y
+CONFIG_TEST_RANDOM_GENERATOR=y
+
+CONFIG_NET_L2_DUMMY=y
+
+CONFIG_DNS_RESOLVER=y
+CONFIG_DNS_RESOLVER_MAX_SERVERS=2
+CONFIG_DNS_NUM_OF_CONCUR_QUERIES=1
+
+CONFIG_DNS_SERVER_IP_ADDRESSES=y
+CONFIG_DNS_SERVER1="192.0.2.2"
+CONFIG_DNS_SERVER2="192.0.2.2:5353"
+
+CONFIG_NET_LOG=y
+CONFIG_SYS_LOG_NET_LEVEL=2
+CONFIG_SYS_LOG_SHOW_COLOR=y
+#CONFIG_NET_DEBUG_DNS_RESOLVE=y
+
+CONFIG_NET_IPV4=y
+CONFIG_NET_IPV6=n
+CONFIG_NET_IPV6_DAD=n
+CONFIG_NET_IPV6_MLD=n
+CONFIG_NET_IPV6_ND=n
+CONFIG_NET_ARP=n
+
+CONFIG_PRINTK=y
+CONFIG_ZTEST=y
+
+CONFIG_MAIN_STACK_SIZE=1344

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

@@ -374,18 +374,20 @@ static void dns_query_ipv4_server_count(void)
 			continue;
 		}
 
-		if (ctx->servers[i].dns_server.sa_family == AF_INET) {
-			count++;
+		if (ctx->servers[i].dns_server.sa_family == AF_INET6) {
+			continue;
 		}
 
+		count++;
+
 		if (net_sin(&ctx->servers[i].dns_server)->sin_port ==
 		    ntohs(53)) {
 			port++;
 		}
 	}
 
 	zassert_equal(count, 2, "Invalid number of IPv4 servers");
-	zassert_equal(port, 2, "Invalid number of IPv4 servers with port 53");
+	zassert_equal(port, 1, "Invalid number of IPv4 servers with port 53");
 }
 
 static void dns_query_ipv6_server_count(void)
@@ -402,18 +404,25 @@ static void dns_query_ipv6_server_count(void)
 			continue;
 		}
 
-		if (ctx->servers[i].dns_server.sa_family == AF_INET6) {
-			count++;
+		if (ctx->servers[i].dns_server.sa_family == AF_INET) {
+			continue;
 		}
 
+		count++;
+
 		if (net_sin6(&ctx->servers[i].dns_server)->sin6_port ==
 		    ntohs(53)) {
 			port++;
 		}
 	}
 
+#if defined(CONFIG_NET_IPV6)
 	zassert_equal(count, 2, "Invalid number of IPv6 servers");
-	zassert_equal(port, 2, "Invalid number of IPv6 servers with port 53");
+	zassert_equal(port, 1, "Invalid number of IPv6 servers with port 53");
+#else
+	zassert_equal(count, 0, "Invalid number of IPv6 servers");
+	zassert_equal(port, 0, "Invalid number of IPv6 servers with port 53");
+#endif
 }
 
 static void dns_query_too_many(void)
@@ -671,10 +680,12 @@ void dns_result_numeric_cb(enum dns_resolve_status status,
 	}
 
 	if (info && info->ai_family == AF_INET6) {
+#if defined(CONFIG_NET_IPV6)
 		if (net_ipv6_addr_cmp(&net_sin6(&info->ai_addr)->sin6_addr,
 				      &my_addr3) != true) {
 			zassert_true(false, "IPv6 address does not match");
 		}
+#endif
 	}
 
 	k_sem_give(&wait_data2);

tests/net/lib/dns_resolve/testcase.yaml

@@ -3,3 +3,8 @@ tests:
         tags: dns net
         min_ram: 16
         timeout: 600
+-   test-no-ipv6:
+        tags: dns net
+        min_ram: 16
+        timeout: 600
+        extra_args: CONF_FILE=prj-no-ipv6.conf