/****************************************************************************
* netutils/netlib/netlib_ipv4adaptor.c
*
* Copyright (C) 2017 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <sys/ioctl.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <net/if.h>
#include <nuttx/net/ip.h>
#include "netutils/netlib.h"
#ifdef CONFIG_NET_IPv4
/****************************************************************************
* Priver Functions
****************************************************************************/
/****************************************************************************
* Name: _netlib_ipv4adaptor
*
* Description:
* Given the destination address, destipaddr, return the IP address
* assigned to the network adaptor that connects the sub-net that
* includes destipaddr.
*
* NOTE: This does not account for any routing information that may
* appear in the routing table. A complete solution could involve three
* steps:
*
* 1. Call netlib_ipv4adaptor() to find the address of the network
* adaptor for the destination address.
* 2. If this fails, then look up the router address in the routing table
* that can forward to the destination address, then
* 3. Call netlib_ipv4adaptor() to find the address of the network
* adaptor for that router address.
*
* Input Parameters:
* destipaddr - The destination IPv4 address
* srcipaddr - The location to return that adaptor address that serves
* the sub-net that includes the destination address.
*
* Returned Value:
* Zero (OK) is returned on success with srcipaddr valid. A negated
* errno value is returned on any failure and in this case the srcipaddr
* is not valid.
*
****************************************************************************/
static int _netlib_ipv4adaptor(in_addr_t destipaddr, FAR in_addr_t *srcipaddr)
{
FAR struct ifreq *ifr;
struct ifconf ifc;
size_t allocsize;
size_t buflen;
int nintf;
int ret;
int sd;
int i;
/* REVISIT: Should check the routing table to see if there is a route
* for the destipaddr before finding the device that provides the sub-net.
*/
/* Find the size of the buffer we need to hold the interface descriptions */
ifc.ifc_req = NULL;
ifc.ifc_len = 0;
sd = socket(AF_INET, NETLIB_SOCK_TYPE, 0);
if (sd < 0)
{
ret = -errno;
fprintf(stderr, "ERROR: socket() failed: %d\n", ret);
return ret;
}
ret = ioctl(sd, SIOCGIFCONF, (unsigned long)((uintptr_t)&ifc));
if (ret < 0)
{
ret = -errno;
fprintf(stderr, "ERROR: ioctl(SIOCGIFCONF) failed: %d\n", ret);
goto errout_with_sd;
}
/* Allocate the buffer to hold the interface descriptions */
allocsize = ifc.ifc_len;
ifr = (FAR struct ifreq *)malloc(allocsize);
if (ifr == NULL)
{
fprintf(stderr, "ERROR: Failed to allocate IFC buffer\n");
ret = -ENOMEM;
goto errout_with_sd;
}
/* Get the interface descriptions */
ifc.ifc_req = ifr;
ret = ioctl(sd, SIOCGIFCONF, (unsigned long)((uintptr_t)&ifc));
if (ret < 0)
{
ret = -errno;
fprintf(stderr, "ERROR: ioctl(SIOCGIFCONF) failed: %d\n", ret);
goto errout_with_ifr;
}
/* Find an interface that supports the subnet needed by the provided
* IPv4 address. Be careful! The size of the returned buffer could
* be different if the network device configuration changed in between
* the two calls!
*/
buflen = ifc.ifc_len;
if (buflen > allocsize)
{
/* Something has changed. Limit to the original size (OR do the
* allocation and IOCTL again).
*/
buflen = allocsize;
}
nintf = buflen / sizeof(struct ifreq);
ret = -EHOSTUNREACH;
for (i = 0; i < nintf; i++)
{
FAR struct ifreq *req = &ifr[i];
FAR struct sockaddr_in *addr =
(FAR struct sockaddr_in *)&req->ifr_addr;
struct ifreq maskreq;
FAR struct sockaddr_in *netmask;
/* Get the network mask */
strncpy(maskreq.ifr_name, ifr->ifr_name, IFNAMSIZ);
ret = ioctl(sd, SIOCGIFNETMASK, (unsigned long)((uintptr_t)&maskreq));
if (ret < 0)
{
ret = -errno;
fprintf(stderr, "ERROR: ioctl(SIOCGIFNETMASK) failed: %d\n",
ret);
goto errout_with_ifr;
}
netmask = (FAR struct sockaddr_in *)&maskreq.ifr_addr;
/* Does this device provide the sub-net? */
if (net_ipv4addr_maskcmp(addr->sin_addr.s_addr, destipaddr,
netmask->sin_addr.s_addr))
{
/* Yes.. return the IP address assigned to this adaptor */
*srcipaddr = addr->sin_addr.s_addr;
ret = OK;
break;
}
}
errout_with_ifr:
free(ifr);
errout_with_sd:
close(sd);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: netlib_ipv4adaptor
*
* Description:
* Given the destination address, destipaddr, return the IP address
* assigned to the network adaptor that connects the sub-net that
* includes destipaddr.
*
* If routing table support is enabled, then this logic will account for
* the case where the destination address is not locally accessible. In
* this case, it will return the IP address of the network adaptor that
* provides the correct router to handle that destination address.
*
* Input Parameters:
* destipaddr - The destination IPv4 address
* srcipaddr - The location to return that adaptor address that serves
* the sub-net that includes the destination address.
*
* Returned Value:
* Zero (OK) is returned on success with srcipaddr valid. A negated
* errno value is returned on any failure and in this case the srcipaddr
* is not valid.
*
****************************************************************************/
int netlib_ipv4adaptor(in_addr_t destipaddr, FAR in_addr_t *srcipaddr)
{
int ret;
DEBUGASSERT(srcipaddr != NULL);
ret = _netlib_ipv4adaptor(destipaddr, srcipaddr);
#ifdef HAVE_ROUTE_PROCFS
if (ret < 0)
{
struct in_addr router;
struct in_addr destinaddr;
/* If the first adaptor look-up on the the destination IP address
* failed, then the IP address cannot be sent on any of the currently
* up network devices configured with an IPv4 address.
*
* But perhaps the destination address is on a sub-net that is
* accessible on a router that can be reached through a local network
* adaptor?
*/
destinaddr.s_addr = destipaddr;
ret = netlib_ipv4router(&destinaddr, &router);
if (ret >= 0)
{
/* Yes... try again using the router address as the destination
* address.
*/
ret = _netlib_ipv4adaptor(router.s_addr, srcipaddr);
}
}
#endif
return ret;
}
#endif /* CONFIG_NET_IPv4 */