netutils/netlib: support delete the DNS server address by index or address

examples/bridge/bridge_main.c

@@ -81,6 +81,7 @@ static int briget_net1_setup(void)
   struct dhcpc_state ds;
   void *handle;
   char inetaddr[INET_ADDRSTRLEN];
+  int ret;
 #endif
 
   printf("NET1: Configuring %s\n", CONFIG_EXAMPLES_BRIDGE_NET1_IFNAME);
@@ -162,9 +163,17 @@ static int briget_net1_setup(void)
                             &ds.default_router);
     }
 
-  if (ds.dnsaddr.s_addr != 0)
+  for (int i = 0; i < ds.num_dnsaddr; i++)
     {
-      netlib_set_ipv4dnsaddr(&ds.dnsaddr);
+      if (ds.dnsaddr[i].s_addr != 0)
+        {
+          ret = netlib_set_ipv4dnsaddr(&ds.dnsaddr[i]);
+          if (ret < 0)
+            {
+              nerr("NET1 ERROR: Set DNS server %d:%s address failed: %d\n",
+                   i, inet_ntoa(ds.dnsaddr[i]), ret);
+            }
+        }
     }
 
   dhcpc_close(handle);
@@ -213,6 +222,7 @@ static int briget_net2_setup(void)
   struct dhcpc_state ds;
   void *handle;
   char inetaddr[INET_ADDRSTRLEN];
+  int ret;
 #endif
 
   printf("NET2: Configuring %s\n", CONFIG_EXAMPLES_BRIDGE_NET2_IFNAME);
@@ -288,9 +298,17 @@ static int briget_net2_setup(void)
                             &ds.default_router);
     }
 
-  if (ds.dnsaddr.s_addr != 0)
+  for (int i = 0; i < ds.num_dnsaddr; i++)
     {
-      netlib_set_ipv4dnsaddr(&ds.dnsaddr);
+      if (ds.dnsaddr[i].s_addr != 0)
+        {
+          ret = netlib_set_ipv4dnsaddr(&ds.dnsaddr[i]);
+          if (ret < 0)
+            {
+              nerr("NET2 ERROR: Set DNS server %d:%s address failed: %d\n",
+                   i, inet_ntoa(ds.dnsaddr[i]), ret);
+            }
+        }
     }
 
   dhcpc_close(handle);

examples/discover/discover_main.c

@@ -138,6 +138,7 @@ int main(int argc, FAR char *argv[])
     {
       struct dhcpc_state ds;
       char inetaddr[INET_ADDRSTRLEN];
+      int ret;
 
       dhcpc_request(handle, &ds);
       netlib_set_ipv4addr("eth0", &ds.ipaddr);
@@ -152,9 +153,17 @@ int main(int argc, FAR char *argv[])
           netlib_set_dripv4addr("eth0", &ds.default_router);
         }
 
-      if (ds.dnsaddr.s_addr != 0)
+      for (int i = 0; i < ds.num_dnsaddr; i++)
         {
-          netlib_set_ipv4dnsaddr(&ds.dnsaddr);
+          if (ds.dnsaddr[i].s_addr != 0)
+            {
+              ret = netlib_set_ipv4dnsaddr(&ds.dnsaddr[i]);
+              if (ret < 0)
+                {
+                  nerr("ERROR: Set DNS server %d:%s address failed: %d\n",
+                        i, inet_ntoa(ds.dnsaddr[i]), ret);
+                }
+            }
         }
 
       dhcpc_close(handle);

examples/tcpecho/tcpecho_main.c

@@ -91,6 +91,7 @@ static int tcpecho_netsetup(void)
   struct dhcpc_state ds;
   void *handle;
   char inetaddr[INET_ADDRSTRLEN];
+  int ret;
 #endif
 
   /* Many embedded network interfaces must have a software assigned MAC */
@@ -166,9 +167,17 @@ static int tcpecho_netsetup(void)
       netlib_set_dripv4addr("eth0", &ds.default_router);
     }
 
-  if (ds.dnsaddr.s_addr != 0)
+  for (int i = 0; i < ds.num_dnsaddr; i++)
     {
-      netlib_set_ipv4dnsaddr(&ds.dnsaddr);
+      if (ds.dnsaddr[i].s_addr != 0)
+        {
+          ret = netlib_set_ipv4dnsaddr(&ds.dnsaddr[i]);
+          if (ret < 0)
+            {
+              nerr("ERROR: Set DNS server %d:%s address failed: %d\n",
+                   i, inet_ntoa(ds.dnsaddr[i]), ret);
+            }
+        }
     }
 
   dhcpc_close(handle);

examples/webserver/webserver_main.c

@@ -169,6 +169,7 @@ int main(int argc, FAR char *argv[])
     {
       struct dhcpc_state ds;
       char inetaddr[INET_ADDRSTRLEN];
+      int ret;
 
       dhcpc_request(handle, &ds);
       netlib_set_ipv4addr("eth0", &ds.ipaddr);
@@ -183,9 +184,17 @@ int main(int argc, FAR char *argv[])
           netlib_set_dripv4addr("eth0", &ds.default_router);
         }
 
-      if (ds.dnsaddr.s_addr != 0)
+      for (int i = 0; i < ds.num_dnsaddr; i++)
         {
-          netlib_set_ipv4dnsaddr(&ds.dnsaddr);
+          if (ds.dnsaddr[i].s_addr != 0)
+            {
+              ret = netlib_set_ipv4dnsaddr(&ds.dnsaddr[i]);
+              if (ret < 0)
+                {
+                  nerr("ERROR: Set DNS server %d:%s address failed: %d\n",
+                       i, inet_ntoa(ds.dnsaddr[i]), ret);
+                }
+            }
         }
 
       dhcpc_close(handle);

examples/xmlrpc/xmlrpc_main.c

@@ -41,6 +41,7 @@
  * in the article at: http://www.drdobbs.com/web-development/\
  *    an-embeddable-lightweight-xml-rpc-server/184405364
  */
+
 /* Lightweight Embedded XML-RPC Server main
  *
  * mtj@cogitollc.com
@@ -334,6 +335,7 @@ static int xmlrpc_netinit(void)
     {
       struct dhcpc_state ds;
       char inetaddr[INET_ADDRSTRLEN];
+      int ret;
 
       dhcpc_request(handle, &ds);
       netlib_set_ipv4addr("eth0", &ds.ipaddr);
@@ -348,9 +350,17 @@ static int xmlrpc_netinit(void)
           netlib_set_dripv4addr("eth0", &ds.default_router);
         }
 
-      if (ds.dnsaddr.s_addr != 0)
+      for (int i = 0; i < ds.num_dnsaddr; i++)
         {
-          netlib_set_ipv4dnsaddr(&ds.dnsaddr);
+          if (ds.dnsaddr[i].s_addr != 0)
+            {
+              ret = netlib_set_ipv4dnsaddr(&ds.dnsaddr[i]);
+              if (ret < 0)
+                {
+                  nerr("ERROR: Set DNS server %d:%s address failed: %d\n",
+                       i, inet_ntoa(ds.dnsaddr[i]), ret);
+                }
+            }
         }
 
       dhcpc_close(handle);

include/netutils/dhcpc.h

@@ -55,7 +55,8 @@ struct dhcpc_state
   struct in_addr serverid;
   struct in_addr ipaddr;
   struct in_addr netmask;
-  struct in_addr dnsaddr;
+  struct in_addr dnsaddr[CONFIG_NETDB_DNSSERVER_NAMESERVERS];
+  uint8_t        num_dnsaddr;     /* Number of DNS addresses received */
   struct in_addr default_router;
   uint32_t       lease_time;      /* Lease expires in this number of seconds */
   uint32_t       renewal_time;    /* Seconds to transition to RENEW state(T1) */

include/netutils/netlib.h

@@ -482,10 +482,14 @@ int netlib_ifdown(FAR const char *ifname);
 
 #if defined(CONFIG_NET_IPv4) && defined(CONFIG_NETDB_DNSCLIENT)
 int netlib_set_ipv4dnsaddr(FAR const struct in_addr *inaddr);
+int netlib_del_ipv4dnsaddr(FAR const struct in_addr *inaddr);
+int netlib_del_ipv4dnsaddr_by_index(int index);
 #endif
 
 #if defined(CONFIG_NET_IPv6) && defined(CONFIG_NETDB_DNSCLIENT)
 int netlib_set_ipv6dnsaddr(FAR const struct in6_addr *inaddr);
+int netlib_del_ipv6dnsaddr(FAR const struct in6_addr *inaddr);
+int netlib_del_ipv6dnsaddr_by_index(int index);
 #endif
 
 int netlib_set_mtu(FAR const char *ifname, int mtu);

netutils/dhcpc/dhcpc.c

@@ -378,11 +378,32 @@ static uint8_t dhcpc_parseoptions(FAR struct dhcpc_state *presult,
 
           case DHCP_OPTION_DNS_SERVER:
 
-            /* Get the DNS server address in network order */
+            /* Get the DNS server addresses in network order.
+             * DHCP option 6 can contain multiple DNS server addresses,
+             * each 4 bytes long.
+             */
 
-            if (optptr + 6 <= end)
+            if (optptr + 2 <= end)
               {
-                memcpy(&presult->dnsaddr.s_addr, optptr + 2, 4);
+                uint8_t optlen = *(optptr + 1);
+                uint8_t num_dns = optlen / 4;
+                uint8_t i;
+
+                /* Limit to configured maximum */
+
+                if (num_dns > CONFIG_NETDB_DNSSERVER_NAMESERVERS)
+                  {
+                    num_dns = CONFIG_NETDB_DNSSERVER_NAMESERVERS;
+                  }
+
+                presult->num_dnsaddr = 0;
+                for (i = 0; i < num_dns && (optptr + 2 + i * 4 + 4) <= end;
+                     i++)
+                  {
+                    memcpy(&presult->dnsaddr[i].s_addr, optptr + 2 + i * 4,
+                           4);
+                    presult->num_dnsaddr++;
+                  }
               }
             else
               {
@@ -946,11 +967,22 @@ int dhcpc_request(FAR void *handle, FAR struct dhcpc_state *presult)
         ip4_addr2(presult->netmask.s_addr),
         ip4_addr3(presult->netmask.s_addr),
         ip4_addr4(presult->netmask.s_addr));
-  ninfo("Got DNS server %u.%u.%u.%u\n",
-        ip4_addr1(presult->dnsaddr.s_addr),
-        ip4_addr2(presult->dnsaddr.s_addr),
-        ip4_addr3(presult->dnsaddr.s_addr),
-        ip4_addr4(presult->dnsaddr.s_addr));
+
+  /* Print all DNS servers received */
+
+  if (presult->num_dnsaddr > 0)
+    {
+      uint8_t i;
+      for (i = 0; i < presult->num_dnsaddr; i++)
+        {
+          ninfo("Got DNS server %d: %u.%u.%u.%u\n", i,
+                ip4_addr1(presult->dnsaddr[i].s_addr),
+                ip4_addr2(presult->dnsaddr[i].s_addr),
+                ip4_addr3(presult->dnsaddr[i].s_addr),
+                ip4_addr4(presult->dnsaddr[i].s_addr));
+        }
+    }
+
   ninfo("Got default router %u.%u.%u.%u\n",
         ip4_addr1(presult->default_router.s_addr),
         ip4_addr2(presult->default_router.s_addr),

netutils/netlib/CMakeLists.txt

@@ -47,7 +47,7 @@ if(CONFIG_NETUTILS_NETLIB)
       endif()
     endif()
     if(CONFIG_NETDB_DNSCLIENT)
-      list(APPEND SRCS netlib_setipv4dnsaddr.c)
+      list(APPEND SRCS netlib_setipv4dnsaddr.c netlib_delipv4dnsaddr.c)
     endif()
     if(CONFIG_NET_ROUTE)
       list(APPEND SRCS netlib_ipv4route.c netlib_ipv4router.c)
@@ -70,7 +70,7 @@ if(CONFIG_NETUTILS_NETLIB)
       list(APPEND SRCS netlib_autoconfig.c netlib_obtainipv6addr.c)
     endif()
     if(CONFIG_NETDB_DNSCLIENT)
-      list(APPEND SRCS netlib_setipv6dnsaddr.c)
+      list(APPEND SRCS netlib_setipv6dnsaddr.c netlib_delipv6dnsaddr.c)
     endif()
     if(CONFIG_NET_ROUTE)
       list(APPEND SRCS netlib_ipv6route.c netlib_ipv6router.c)

netutils/netlib/Makefile

@@ -47,7 +47,7 @@ CSRCS += netlib_getarptab.c
 endif
 endif
 ifeq ($(CONFIG_NETDB_DNSCLIENT),y)
-CSRCS += netlib_setipv4dnsaddr.c
+CSRCS += netlib_setipv4dnsaddr.c netlib_delipv4dnsaddr.c
 endif
 ifeq ($(CONFIG_NET_ROUTE),y)
 CSRCS += netlib_ipv4route.c netlib_ipv4router.c
@@ -71,7 +71,7 @@ CSRCS += netlib_autoconfig.c
 CSRCS += netlib_obtainipv6addr.c
 endif
 ifeq ($(CONFIG_NETDB_DNSCLIENT),y)
-CSRCS += netlib_setipv6dnsaddr.c
+CSRCS += netlib_setipv6dnsaddr.c netlib_delipv6dnsaddr.c
 endif
 ifeq ($(CONFIG_NET_ROUTE),y)
 CSRCS += netlib_ipv6route.c netlib_ipv6router.c

netutils/netlib/netlib_delipv4dnsaddr.c

@@ -0,0 +1,97 @@
+/****************************************************************************
+ * apps/netutils/netlib/netlib_delipv4dnsaddr.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/socket.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+#include <netinet/in.h>
+#include <nuttx/net/dns.h>
+
+#include "netutils/netlib.h"
+
+#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NETDB_DNSCLIENT)
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: netlib_del_ipv4dnsaddr
+ *
+ * Description:
+ *   Remove a DNS server IPv4 address from the list by address
+ *
+ * Parameters:
+ *   inaddr   The address to remove
+ *
+ * Return:
+ *   Zero (OK) is returned on success; A negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+int netlib_del_ipv4dnsaddr(FAR const struct in_addr *inaddr)
+{
+  struct sockaddr_in addr;
+  int ret = -EINVAL;
+
+  if (inaddr)
+    {
+      addr.sin_family = AF_INET;
+      addr.sin_port   = 0;
+      memcpy(&addr.sin_addr, inaddr, sizeof(struct in_addr));
+      bzero(&addr.sin_zero, sizeof(addr.sin_zero));
+
+      ret = dns_del_nameserver((FAR const struct sockaddr *)&addr,
+                               sizeof(struct sockaddr_in));
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: netlib_del_ipv4dnsaddr_by_index
+ *
+ * Description:
+ *   Remove a DNS server IPv4 address from the list by index (0-based)
+ *
+ * Parameters:
+ *   index: The index of the DNS server to remove (0=first,  1=second, etc.)
+ *
+ * Return:
+ *   Zero (OK) is returned on success; A negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+int netlib_del_ipv4dnsaddr_by_index(int index)
+{
+  return dns_del_nameserver_by_index(index);
+}
+
+#endif /* CONFIG_NET_IPv4 && CONFIG_NETDB_DNSCLIENT */