Networking: Add NetDB support for the local loopback device

ChangeLog

@@ -10873,4 +10873,7 @@
 	  Pavel Pisa (2015-08-23).
 	* net/ ande include/nuttx/net:  Remove references to PPP as a
 	  link layer protocol (2015-08-24).
-
+	* net/, drivers/net, and include/net:  Add definitions to support
+	  a local loopback device and link layer (2015-08-24).
+	* libc/netdb, net/loopback, include/nuttx/net:  Add NetDB support
+	  for the local loopback device (2015-08-24).

include/nuttx/net/loopback.h

@@ -0,0 +1,98 @@
+/****************************************************************************
+ * include/nuttx/net/loopback.h
+ * Definitions for use with local loopback device
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory nutt <gnutt@nuttx.org>
+ *
+ * Includes some definitions that a compatible with the LGPL GNU C Library
+ * header file of the same name.
+ *
+ * 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.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_NUTTX_NET_LOOPBACK_H
+#define __INCLUDE_NUTTX_NET_LOOPBACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <nuttx/net/netconfig.h>
+
+#ifdef CONFIG_NETDEV_LOOPBACK
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+#ifdef CONFIG_LIBC_NETDB
+/* Local loopback hostname */
+
+EXTERN const char           g_lo_hostname[];
+#endif
+
+/* Local loopback addresses */
+
+EXTERN const in_addr_t      g_lo_ipv4addr;
+EXTERN const in_addr_t      g_lo_ipv4mask;
+EXTERN const net_ipv6addr_t g_lo_ipv6addr;
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_NETDEV_LOOPBACK */
+#endif /* __INCLUDE_NUTTX_NET_LOOPBACK_H */