Squashed commit of the following:

    net/netdev:  Add implementation of if_nametoindex() and if indextoname().
    net/pkt:  Raw AF_PACKET sockets now depend on CONFIG_NETDEV_IFINDEX.
    net/procfs:  Tweak to handle traversal of interfaces if CONFIG_NETDEV_IFINDEX is not defined.
    net/netdev.h:  Update netdev_findbyaddr() to use the assigned device index.
    Trivial typo fix
    net/netdev:  Add support for assigned an interface index to a device when it is regisgtered.

include/net/if.h

@@ -247,4 +247,39 @@ struct ifconf
  * Public Function Prototypes
  *******************************************************************************************/
 
+/*******************************************************************************************
+ * Name: if_nametoindex
+ *
+ * Description:
+ *   The if_nametoindex() function returns the interface index corresponding to name ifname.
+ *
+ * Input Parameters:
+ *   ifname - The interface name
+ *
+ * Returned Value:
+ *   The corresponding index if ifname is the name of an interface; otherwise, zero.
+ *
+ *******************************************************************************************/
+
+unsigned int if_nametoindex(FAR const char *ifname);
+
+/*******************************************************************************************
+ * Name: if_indextoname
+ *
+ * Description:
+ *   The if_indextoname() function maps an interface index to its corresponding name.
+ *
+ * Input Parameters:
+ *   ifname  - Points to a buffer of at least IF_NAMESIZE bytes.  if_indextoname() will
+ *             place in this buffer the name of the interface with index ifindex.
+ *
+ * Returned Value:
+ *   If ifindex is an interface index, then the function will return the value supplied by
+ *   ifname. Otherwise, the function returns a NULL pointer and sets errno to indicate the
+*    error.
+ *
+ *******************************************************************************************/
+
+FAR char *if_indextoname(unsigned int ifindex, FAR char *ifname);
+
 #endif /* __INCLUDE_NET_IF_H */

include/nuttx/net/netdev.h

@@ -3,7 +3,7 @@
  * Defines architecture-specific device driver interfaces to the NuttX
  * network.
  *
- *   Copyright (C) 2007, 2009, 2011-2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011-2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Derived largely from portions of uIP with has a similar BSD-styple license:
@@ -241,6 +241,11 @@ struct net_driver_s
 
   uint8_t d_lltype;             /* See enum net_lltype_e */
   uint8_t d_llhdrlen;           /* Link layer header size */
+
+#ifdef CONFIG_NETDEV_IFINDEX
+  uint8_t d_ifindex;            /* Device index */
+#endif
+
   uint16_t d_mtu;               /* Maximum packet size */
 #ifdef CONFIG_NET_TCP
   uint16_t d_recvwndo;          /* TCP receive window size */

net/netdev/Kconfig

@@ -24,4 +24,16 @@ config NETDEV_WIRELESS_IOCTL
 	---help---
 		Enable support for wireless device ioctl() commands
 
+config NETDEV_IFINDEX
+	bool "Enable IF index support"
+	default n
+	---help---
+		Enable support for references devices by an interface index.
+
+		This feature is automatically enabled when raw, PACKET sockets
+		are enabled.
+
+		When enabled, these option also enables the user interfaces:
+		if_nametoindex() and if_indextoname().
+
 endmenu # Network Device Operations

net/netdev/Make.defs

@@ -41,6 +41,10 @@ NETDEV_CSRCS += netdev_count.c netdev_ifconf.c netdev_foreach.c
 NETDEV_CSRCS += netdev_unregister.c netdev_carrier.c netdev_default.c
 NETDEV_CSRCS += netdev_verify.c netdev_lladdrsize.c
 
+ifeq ($(CONFIG_NETDEV_IFINDEX),y)
+NETDEV_CSRCS += netdev_indextoname.c netdev_nametoindex.c
+endif
+
 # Include netdev build support
 
 DEPPATH += --dep-path netdev

net/netdev/netdev.h

@@ -47,6 +47,16 @@
 
 #include <nuttx/net/ip.h>
 
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* If CONFIG_NETDEV_IFINDEX is enabled then there is limit to the number of
+ * devices that can be registered due to the nature of some static data.
+ */
+
+#define MAX_IFINDEX  32
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/
@@ -70,6 +80,17 @@ extern "C"
 EXTERN struct net_driver_s *g_netdevices;
 #endif
 
+#ifdef CONFIG_NETDEV_IFINDEX
+/* The set of network devices that have been registered.  This is used to
+ * assign a unique device index to the newly registered device.
+ *
+ * REVISIT:  The width of g_nassigned limits the number of registered
+ * devices to 32 (MAX_IFINDEX).
+ */
+
+EXTERN uint32_t g_devset;
+#endif
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -120,9 +141,6 @@ bool netdev_verify(FAR struct net_driver_s *dev);
  * Returned Value:
  *  Pointer to driver on success; null on failure
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #if CONFIG_NSOCKET_DESCRIPTORS > 0
@@ -144,9 +162,6 @@ FAR struct net_driver_s *netdev_findbyname(FAR const char *ifname);
  * Returned Value:
  *  0:Enumeration completed 1:Enumeration terminated early by callback
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 int netdev_foreach(netdev_callback_t callback, FAR void *arg);
@@ -165,9 +180,6 @@ int netdev_foreach(netdev_callback_t callback, FAR void *arg);
  * Returned Value:
  *  Pointer to driver on success; null on failure
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #if CONFIG_NSOCKET_DESCRIPTORS > 0
@@ -190,9 +202,6 @@ FAR struct net_driver_s *netdev_findby_ipv4addr(in_addr_t lipaddr,
  * Returned Value:
  *  Pointer to driver on success; null on failure
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #ifdef CONFIG_NET_IPv6
@@ -205,25 +214,80 @@ FAR struct net_driver_s *netdev_findby_ipv6addr(const net_ipv6addr_t lipaddr,
  * Name: netdev_findbyindex
  *
  * Description:
- *   Find a previously registered network device by its position in the
- *   list of registered devices.  NOTE that this function is not a safe way
- *   to enumerate network devices:  There could be changes to the list of
- *   registered device causing a given index to be meaningless (unless, of
- *   course, the caller keeps the network locked).
+ *   Find a previously registered network device by assigned interface index.
  *
  * Input Parameters:
- *   index - the index of the interface to file
+ *   ifindex - The interface index
  *
  * Returned Value:
- *  Pointer to driver on success; NULL on failure.  This function can only
- *  fail if there are fewer registered interfaces than could be indexed.
+ *  Pointer to driver on success; NULL on failure.  This function will return
+ *  NULL only if there is no device corresponding to the provided index.
  *
- * Assumptions:
- *  Called from normal user mode
+ ****************************************************************************/
+
+FAR struct net_driver_s *netdev_findbyindex(int ifindex);
+
+/****************************************************************************
+ * Name: netdev_nextindex
+ *
+ * Description:
+ *   Return the interface index to the next valid device.
+ *
+ * Input Parameters:
+ *   ifindex - The first interface index to check.  Usually in a traversal
+ *             this would be the previous inteface index plus 1.
+ *
+ * Returned Value:
+ *   The interface index for the next network driver.  -ENODEV is returned if
+ *   there are no further devices with assigned interface indices.
  *
  ****************************************************************************/
 
-FAR struct net_driver_s *netdev_findbyindex(int index);
+#ifdef CONFIG_NETDEV_IFINDEX
+int netdev_nextindex(int ifindex);
+#endif
+
+/****************************************************************************
+ * Name: netdev_indextoname
+ *
+ * Description:
+ *   The if_indextoname() function maps an interface index to its
+ *   corresponding name.
+ *
+ * Input Parameters:
+ *   ifname  - Points to a buffer of at least IF_NAMESIZE bytes.
+ *             if_indextoname() will place in this buffer the name of the
+ *             interface with index ifindex.
+ *
+ * Returned Value:
+ *   If ifindex is an interface index, then the function will return zero
+ *   (OK). Otherwise, the function returns a negated errno value;
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_NETDEV_IFINDEX
+int netdev_indextoname(unsigned int ifindex, FAR char *ifname);
+#endif
+
+/****************************************************************************
+ * Name: netdev_nametoindex
+ *
+ * Description:
+ *   The if_nametoindex() function returns the interface index corresponding
+ *   to name ifname.
+ *
+ * Input Parameters:
+ *   ifname - The interface name
+ *
+ * Returned Value:
+ *   The corresponding index if ifname is the name of an interface;
+ *   otherwise, a negated errno value is returned.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_NETDEV_IFINDEX
+unsigned int netdev_nametoindex(FAR const char *ifname);
+#endif
 
 /****************************************************************************
  * Name: netdev_default
@@ -244,9 +308,6 @@ FAR struct net_driver_s *netdev_findbyindex(int index);
  * Returned Value:
  *  Pointer to default network driver on success; null on failure
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #if CONFIG_NSOCKET_DESCRIPTORS > 0
@@ -267,9 +328,6 @@ FAR struct net_driver_s *netdev_default(void);
  * Returned Value:
  *  None
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #if CONFIG_NSOCKET_DESCRIPTORS > 0
@@ -291,9 +349,6 @@ void netdev_ipv4_txnotify(in_addr_t lipaddr, in_addr_t ripaddr);
  * Returned Value:
  *  None
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #ifdef CONFIG_NET_IPv6
@@ -316,9 +371,6 @@ void netdev_ipv6_txnotify(FAR const net_ipv6addr_t lipaddr,
  * Returned Value:
  *  None
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 void netdev_txnotify_dev(FAR struct net_driver_s *dev);
@@ -335,9 +387,6 @@ void netdev_txnotify_dev(FAR struct net_driver_s *dev);
  * Returned Value:
  *   The number of network devices
  *
- * Assumptions:
- *  Called from normal user mode
- *
  ****************************************************************************/
 
 #if CONFIG_NSOCKET_DESCRIPTORS > 0