Some networking logic was used helpers from apps/netutils. Not good. Quick fix is to duplicate logic

libc/netdb/Make.defs

@@ -48,7 +48,7 @@ endif
 # Add DNS lookup support
 
 ifeq ($(CONFIG_NETDB_DNSCLIENT),y)
-CSRCS += lib_dnsclient.c
+CSRCS += lib_dnsclient.c lib_getdnsaddr.c
 endif
 
 # Add the net directory to the build

libc/netdb/lib_dns.h

@@ -57,11 +57,11 @@
 /* DNS client configuration **************************************************/
 
 #ifndef CONFIG_NETDB_DNSCLIENT_ENTRIES
-#  define RESOLV_ENTRIES 4
-#else
-#  define RESOLV_ENTRIES CONFIG_NETDB_DNSCLIENT_ENTRIES
+#  define CONFIG_NETDB_DNSCLIENT_ENTRIES 4
 #endif
 
+#define RESOLV_ENTRIES CONFIG_NETDB_DNSCLIENT_ENTRIES
+
 #ifndef CONFIG_NETDB_DNSCLIENT_MAXRESPONSE
 #  define CONFIG_NETDB_DNSCLIENT_MAXRESPONSE 96
 #endif

libc/netdb/lib_getdnsaddr.c

@@ -0,0 +1,98 @@
+/****************************************************************************
+ * libc/netdb/lib_dnsgetaddr.c
+ *
+ *   Copyright (C) 2007-2009, 2011, 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/socket.h>
+
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+
+#include <netinet/in.h>
+
+#include <nuttx/net/dns.h>
+
+#include <apps/netutils/netlib.h>
+
+#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NETDB_DNSCLIENT)
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: dns_getaddr
+ *
+ * Description:
+ *   Get the DNS server IPv4 address
+ *
+ * Parameters:
+ *   ipaddr   The location to return the IPv4 address
+ *
+ * Return:
+ *   Zero (OK) is returned on success; A negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+int dns_getaddr(FAR struct in_addr *inaddr)
+{
+  struct sockaddr_in addr;
+  socklen_t addrlen;
+  int ret = -EINVAL;
+
+  if (inaddr)
+    {
+      addrlen = sizeof(struct sockaddr_in);
+      ret = dns_getserver((FAR struct sockaddr *)&addr, &addrlen);
+      if (ret >= 0)
+        {
+          /* Sanity check */
+
+          DEBUGASSERT(addr.sin_family == AF_INET &&
+                      addrlen == sizeof(struct sockaddr_in));
+          memcpy(inaddr, &addr.sin_addr, sizeof(struct in_addr));
+        }
+    }
+
+  return ret;
+}
+
+#endif /* CONFIG_NET_IPv4 && CONFIG_NETDB_DNSCLIENT */