libdabba/nic.c

   1 /**
   2  * \file nic.c
   3  * \author written by Emmanuel Roullit emmanuel.roullit@gmail.com (c) 2011
   4  * \date 2011
   5  */
   6
   7 /* __LICENSE_HEADER_BEGIN__ */
   8
   9 /*
  10  * Copyright (C) 2011   Emmanuel Roullit <emmanuel.roullit@gmail.com>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or (at
  15  * your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  20  * for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License along
  23  * with this program; if not, write to the Free Software Foundation, Inc.,
  24  * 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
  25  *
  26  */
  27
  28 /* __LICENSE_HEADER_END__ */
  29
  30 #include <assert.h>
  31 #include <errno.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34
  35 #include <sys/socket.h>
  36 #include <sys/ioctl.h>
  37 #include <net/if.h>
  38
  39 #include <libdabba/nic.h>
  40 #include <libdabba/strlcpy.h>
  41
  42 /**
  43  * \brief Get the interface index of a specific interface
  44  * \param[in]   dev     Device name
  45  * \param[out]  index   Interface index of the interface
  46  * \return 0 on success, errno from \c socket(2), \c ioctl(2)
  47  * \return or \c close(2) on failure
  48  *
  49  * This function queries the kernel about the interface
  50  * index related to the interface name.
  51  */
  52
  53 int devname_to_ifindex(const char *const dev, int *index)
  54 {
  55         int ret;
  56         int sock;
  57         struct ifreq ethreq;
  58
  59         assert(dev);
  60         assert(index);
  61
  62         if (strcmp(dev, ANY_INTERFACE) == 0) {
  63                 *index = 0;
  64                 return (0);
  65         }
  66
  67         sock = socket(AF_INET, SOCK_DGRAM, 0);
  68
  69         if (sock < 0)
  70                 return (errno);
  71
  72         memset(&ethreq, 0, sizeof(ethreq));
  73         strlcpy(ethreq.ifr_name, dev, sizeof(ethreq.ifr_name));
  74
  75         ret = ioctl(sock, SIOCGIFINDEX, &ethreq);
  76
  77         close(sock);
  78
  79         if (ret < 0)
  80                 return (errno);
  81
  82         *index = ethreq.ifr_ifindex;
  83
  84         return (0);
  85 }
  86
  87 /**
  88  * \brief Get the interface name from an interface index
  89  * \param[in]   index   Interface index of the interface
  90  * \param[out]  dev     Device name
  91  * \param[in]   dev_len Device name buffer length
  92  * \return 0 on success, errno from \c socket(2), \c ioctl(2)
  93  * \return or \c close(2) on failure
  94  *
  95  * This function queries the kernel about the interface
  96  * index related to the interface name.
  97  */
  98
  99 int ifindex_to_devname(const int index, char *dev, size_t dev_len)
 100 {
 101         const char alldev[] = ANY_INTERFACE;
 102         struct ifreq ethreq;
 103         int ret, sock;
 104
 105         assert(index >= 0);
 106         assert(dev);
 107         assert(dev_len >= IFNAMSIZ);
 108
 109         if (index == 0) {
 110                 strlcpy(dev, alldev, dev_len);
 111                 return (0);
 112         }
 113
 114         sock = socket(AF_INET, SOCK_DGRAM, 0);
 115
 116         if (sock < 0)
 117                 return (errno);
 118
 119         memset(&ethreq, 0, sizeof(ethreq));
 120         ethreq.ifr_ifindex = index;
 121
 122         ret = ioctl(sock, SIOCGIFNAME, &ethreq);
 123
 124         close(sock);
 125
 126         if (ret < 0)
 127                 return (errno);
 128
 129         strlcpy(dev, ethreq.ifr_name, dev_len);
 130
 131         return (0);
 132 }