Step 1 in /etc/resolv.conf support

TODO

@@ -17,7 +17,7 @@ nuttx/
   (8)  Kernel/Protected Build
   (4)  C++ Support
   (6)  Binary loaders (binfmt/)
- (13)  Network (net/, drivers/net)
+ (12)  Network (net/, drivers/net)
   (4)  USB (drivers/usbdev, drivers/usbhost)
   (1)  Other drivers (drivers/)
  (11)  Libraries (libc/, libm/)
@@ -1008,36 +1008,6 @@ o Network (net/, drivers/net)
   Priority:    Low.  I don't know of any issues now, but I am sure that
                someone will encounter this in the future.
 
-  Title:       GLOBAL DNS ADDRESS
-  Description: Currently there is a single, global DNS server address.  This
-               address resides in user space (owned by libc/netdb) but is
-               accessed by network code in kernel space (net/procfs).  This
-               works in a FLAT build, not not in other build modules.
-
-               Things would be really weird in the kernel build:  There
-               would be a separate name server address and a separate netdb
-               DNS client in each process.  That can't be right.
-
-               The Linux kernel has no knowledge at all about DNS addresses.
-               DNS addresses are retained in /etc/resolv.conf in records
-               ike:
-
-                 nameserver <nameserver IP addresses>
-
-               The nameserver is associated with the device only through
-               the routing of the IP address.  And this is how there can
-               be multiple, global DNS addresses.
-
-               Conclusion: The logic in net/procfs needs to be re-designed
-               so that it does not use the DNS address.  The DNS address(es)
-               should to applied to the device status by logic in the
-               implementation of the NSH ifconfig command.  This would be,
-               unfortunately, a significant re-design since the formatting
-               is currently performed in net/procfs.
-  Status:      Open
-  Priority:    Low.  I doubt that there are any multiple NIC, multiple DNS
-               server configurations
-
   Title:       MISSING netdb INTERFACES
   Description: There is no implementation for many netdb interfaces such as
                getaddrinfo(), freeaddrinfo(), getnameinfo(), etc.

include/nuttx/net/dns.h

@@ -178,44 +178,35 @@ extern "C"
 #endif
 
 /****************************************************************************
- * Name: dns_setserver
+ * Name: dns_add_nameserver
  *
  * Description:
- *   Configure which DNS server to use for queries.  Set the port number
+ *   Configure a DNS server to use for queries.  Set the port number to zero
- *   to zero to use the default DNS server port.
+ *   to use the default DNS server port.
  *
  ****************************************************************************/
 
-int dns_setserver(FAR const struct sockaddr *addr, socklen_t addrlen);
+int dns_add_nameserver(FAR const struct sockaddr *addr, socklen_t addrlen);
 
 /****************************************************************************
- * Name: dns_getserver
+ * Name: dns_del_nameserver
  *
  * Description:
- *   Obtain the currently configured DNS server.
+ *   Remove a DNS server so it is no longer available for further use.
  *
  ****************************************************************************/
-
+/* REVISIT: Not implemented */
-int dns_getserver(FAR struct sockaddr *addr, FAR socklen_t *addrlen);
 
 /****************************************************************************
- * Name: dns_getaddr
+ * Name: dns_foreach_nameserver
  *
  * Description:
- *   Get the DNS server IPv4 address
+ *   Traverse each nameserver entry in the resolv.conf file and perform the
- *
+ *   the provided callback.
- * Parameters:
- *   ipaddr   The location to return the IPv4 address
- *
- * Return:
- *   Zero (OK) is returned on success; A negated errno value is returned
- *   on failure.
  *
  ****************************************************************************/
 
-#ifdef CONFIG_NET_IPv4
+int dns_foreach_nameserver(dns_callback_t callback, FAR void *arg);
-int dns_getaddr(FAR struct in_addr *inaddr);
-#endif
 
 #undef EXTERN
 #if defined(__cplusplus)

libc/Kconfig

@@ -533,6 +533,22 @@ config NETDB_BUFSIZE
 
 endif # NETDB_HOSTFILE
 
+menuconfig NETDB_RESOLVCONF
+	bool "DNS server file support"
+	default n
+	depends on FS_READABLE
+	select LIBC_NETDB
+	---help---
+		Enable DNS server look ups in resolver file.
+
+if NETDB_RESOLVCONF
+
+config NETDB_RESOLVCONF_PATH
+	string "Path to host configuration file"
+	default "/etc/resolv.conf"
+
+endif # NETDB_RESOLVCONF
+
 config NETDB_DNSCLIENT
 	bool "DNS Name resolution"
 	default n
@@ -615,7 +631,7 @@ config NETDB_DNSSERVER_IPv4ADDR
 	depends on NETDB_DNSSERVER_IPv4
 	---help---
 		Default DNS server IPv4 address in host byte order.  Default value
-		10.0.0.0.1.  This may be changed via dns_setserver().
+		10.0.0.0.1.  This may be changed via dns_add_nameserver().
 
 if NETDB_DNSSERVER_IPv6
 

libc/net/lib_inetpton.c

@@ -372,7 +372,7 @@ static int inet_ipv6_pton(FAR const char *src, FAR void *dest)
  *   af   - The af argument specifies the family of the address. This can be
  *          AF_INET or AF_INET6.
  *   src  - The src argument points to the string being passed in.
- *   dest - The dest argument points to a numstr into which the function stores
+ *   dest - The dest argument points to memory into which the function stores
  *          the numeric address; this must be large enough to hold the numeric
  *          address (32 bits for AF_INET, 128 bits for AF_INET6).
  *

libc/netdb/Make.defs

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

libc/netdb/lib_dns.h

@@ -74,6 +74,15 @@
 #  define CONFIG_NETDB_DNSCLIENT_LIFESEC 3600
 #endif
 
+#define DNS_MAX_LINE 80
+#define NETDB_DNS_KEYWORD "nameserver"
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+typedef CODE int (*dns_callback_t)(FAR void *arg, int af, FAR void *addr);
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/
@@ -156,7 +165,7 @@ int dns_find_answer(FAR const char *hostname, FAR struct sockaddr *addr,
                     FAR socklen_t *addrlen);
 #endif
 
-#undef EXTERN
+o#undef EXTERN
 #if defined(__cplusplus)
 }
 #endif

libc/netdb/lib_dnsclient.c

@@ -5,7 +5,7 @@
  * The uIP DNS resolver functions are used to lookup a hostname and
  * map it to a numerical IP address.
  *
- *   Copyright (C) 2007, 2009, 2012, 2014-2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2012, 2014-2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Based heavily on portions of uIP:
@@ -227,8 +227,8 @@ static bool dns_initialize(void)
        addr4.sin_port        = DNS_DEFAULT_PORT;
        addr4.sin_addr.s_addr = HTONL(CONFIG_NETDB_DNSSERVER_IPv4ADDR);
 
-       ret = dns_setserver((FAR struct sockaddr *)&addr4,
+       ret = dns_add_nameserver((FAR struct sockaddr *)&addr4,
-                           sizeof(struct sockaddr_in));
+                                sizeof(struct sockaddr_in));
        if (ret < 0)
          {
            return false;
@@ -244,8 +244,8 @@ static bool dns_initialize(void)
        addr6.sin6_port   = DNS_DEFAULT_PORT;
        memcpy(addr6.sin6_addr.s6_addr, g_ipv6_hostaddr, 16);
 
-       ret = dns_setserver((FAR struct sockaddr *)&addr6,
+       ret = dns_add_nameserver((FAR struct sockaddr *)&addr6,
-                           sizeof(struct sockaddr_in6));
+                                sizeof(struct sockaddr_in6));
        if (ret < 0)
          {
            return false;
@@ -877,77 +877,6 @@ int dns_query(int sd, FAR const char *hostname, FAR struct sockaddr *addr,
   return -ETIMEDOUT;
 }
 
-/****************************************************************************
- * Name: dns_setserver
- *
- * Description:
- *   Configure which DNS server to use for queries
- *
- ****************************************************************************/
-
-int dns_setserver(FAR const struct sockaddr *addr, socklen_t addrlen)
-{
-  FAR uint16_t *pport;
-  size_t copylen;
-
-  DEBUGASSERT(addr != NULL);
-
-  /* Copy the new server IP address into our private global data structure */
-
-#ifdef CONFIG_NET_IPv4
-  /* Check for an IPv4 address */
-
-  if (addr->sa_family == AF_INET)
-    {
-      /* Set up for the IPv4 address copy */
-
-      copylen = sizeof(struct sockaddr_in);
-      pport   = &g_dns_server.ipv4.sin_port;
-    }
-  else
-#endif
-
-#ifdef CONFIG_NET_IPv6
-  /* Check for an IPv6 address */
-
-  if (addr->sa_family == AF_INET6)
-    {
-      /* Set up for the IPv6 address copy */
-
-      copylen = sizeof(struct sockaddr_in6);
-      pport   = &g_dns_server.ipv6.sin6_port;
-    }
-  else
-#endif
-    {
-      nvdbg("ERROR: Unsupported family: %d\n", addr->sa_family);
-      return -ENOSYS;
-    }
-
-  /* Copy the IP address */
-
-  if (addrlen < copylen)
-    {
-      nvdbg("ERROR: Invalid addrlen %ld for family %d\n",
-            (long)addrlen, addr->sa_family);
-      return -EINVAL;
-    }
-
-  memcpy(&g_dns_server.addr, addr, copylen);
-
-  /* A port number of zero means to use the default DNS server port number */
-
-  if (*pport == 0)
-    {
-      *pport = HTONS(DNS_DEFAULT_PORT);
-    }
-
-  /* We now have a valid DNS address */
-
-  g_dns_address = true;
-  return OK;
-}
-
 /****************************************************************************
  * Name: dns_getserver
  *

libc/netdb/lib_getdnsaddr.c

@@ -1,98 +0,0 @@
-/****************************************************************************
- * 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 */

net/procfs/netdev_statistics.c

@@ -47,7 +47,6 @@
 #include <netinet/ether.h>
 
 #include <nuttx/net/netdev.h>
-#include <nuttx/net/dns.h>
 
 #include "netdev/netdev.h"
 #include "utils/utils.h"
@@ -246,17 +245,6 @@ static int netprocfs_ipaddresses(FAR struct netprocfs_file_s *netfile)
   addr.s_addr = dev->d_netmask;
   len += snprintf(&netfile->line[len], NET_LINELEN - len,
                   "Mask:%s\n", inet_ntoa(addr));
-
-#if defined(CONFIG_BUILD_FLAT) && defined(CONFIG_NETDB_DNSCLIENT)
-  /* Show the IPv4 DNS address */
-  /* REVISIT:  DNS client is global, not per device, and resides in the
-   * application space and is not generally accessible from kernel space.
-   */
-
-  dns_getaddr(&addr);
-  len += snprintf(&netfile->line[len], NET_LINELEN - len,
-                  "\tDNSaddr:%s\n", inet_ntoa(addr));
-#endif
 #endif
 
 #ifdef CONFIG_NET_IPv6
@@ -279,11 +267,6 @@ static int netprocfs_ipaddresses(FAR struct netprocfs_file_s *netfile)
       len += snprintf(&netfile->line[len], NET_LINELEN - len,
                       "\tinet6 DRaddr:%s/%d\n", addrstr, preflen);
     }
-
-#if defined(CONFIG_BUILD_FLAT) && defined(CONFIG_NETDB_DNSCLIENT)
-  /* Show the IPv6 DNS address */
-#  warning Missing logic
-#endif
 #endif
 
   len += snprintf(&netfile->line[len], NET_LINELEN - len, "\n");