networking/ipcalc.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini ipcalc implementation for busybox
   4  *
   5  * By Jordan Crouse <jordan@cosmicpenguin.net>
   6  *    Stephan Linz  <linz@li-pro.net>
   7  *
   8  * This is a complete reimplementation of the ipcalc program
   9  * from Red Hat.  I didn't look at their source code, but there
  10  * is no denying that this is a loving reimplementation
  11  *
  12  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  13  */
  14
  15 #include "busybox.h"
  16 #include <ctype.h>
  17 #include <getopt.h>
  18 #include <sys/socket.h>
  19 #include <arpa/inet.h>
  20
  21 #define CLASS_A_NETMASK ntohl(0xFF000000)
  22 #define CLASS_B_NETMASK ntohl(0xFFFF0000)
  23 #define CLASS_C_NETMASK ntohl(0xFFFFFF00)
  24
  25 static unsigned long get_netmask(unsigned long ipaddr)
  26 {
  27         ipaddr = htonl(ipaddr);
  28
  29         if ((ipaddr & 0xC0000000) == 0xC0000000)
  30                 return CLASS_C_NETMASK;
  31         else if ((ipaddr & 0x80000000) == 0x80000000)
  32                 return CLASS_B_NETMASK;
  33         else if ((ipaddr & 0x80000000) == 0)
  34                 return CLASS_A_NETMASK;
  35         else
  36                 return 0;
  37 }
  38
  39 #ifdef CONFIG_FEATURE_IPCALC_FANCY
  40 static int get_prefix(unsigned long netmask)
  41 {
  42         unsigned long msk = 0x80000000;
  43         int ret = 0;
  44
  45         netmask = htonl(netmask);
  46         while (msk) {
  47                 if (netmask & msk)
  48                         ret++;
  49                 msk >>= 1;
  50         }
  51         return ret;
  52 }
  53 #else
  54 int get_prefix(unsigned long netmask);
  55 #endif
  56
  57
  58 #define NETMASK   0x01
  59 #define BROADCAST 0x02
  60 #define NETWORK   0x04
  61 #define NETPREFIX 0x08
  62 #define HOSTNAME  0x10
  63 #define SILENT    0x20
  64
  65 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
  66         static const struct option long_options[] = {
  67                 { "netmask",     no_argument, NULL, 'm' },
  68                 { "broadcast",   no_argument, NULL, 'b' },
  69                 { "network",     no_argument, NULL, 'n' },
  70 # if ENABLE_FEATURE_IPCALC_FANCY
  71                 { "prefix",      no_argument, NULL, 'p' },
  72                 { "hostname",    no_argument, NULL, 'h' },
  73                 { "silent",      no_argument, NULL, 's' },
  74 # endif
  75                 { NULL, 0, NULL, 0 }
  76         };
  77 #endif
  78
  79 int ipcalc_main(int argc, char **argv);
  80 int ipcalc_main(int argc, char **argv)
  81 {
  82         unsigned opt;
  83         int have_netmask = 0;
  84         in_addr_t netmask, broadcast, network, ipaddr;
  85         struct in_addr a;
  86         char *ipstr;
  87
  88 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
  89         applet_long_options = long_options;
  90 #endif
  91         opt = getopt32(argc, argv, "mbn" USE_FEATURE_IPCALC_FANCY("phs"));
  92         argc -= optind;
  93         argv += optind;
  94         if (opt & (BROADCAST | NETWORK | NETPREFIX)) {
  95                 if (argc > 2 || argc <= 0)
  96                         bb_show_usage();
  97         } else {
  98                 if (argc != 1)
  99                         bb_show_usage();
 100         }
 101         if (opt & SILENT)
 102                 logmode = LOGMODE_NONE; /* Suppress error_msg() output */
 103
 104         ipstr = argv[0];
 105         if (ENABLE_FEATURE_IPCALC_FANCY) {
 106                 unsigned long netprefix = 0;
 107                 char *prefixstr;
 108
 109                 prefixstr = ipstr;
 110
 111                 while (*prefixstr) {
 112                         if (*prefixstr == '/') {
 113                                 *prefixstr = (char)0;
 114                                 prefixstr++;
 115                                 if (*prefixstr) {
 116                                         unsigned msk;
 117                                         netprefix = xatoul_range(prefixstr, 0, 32);
 118                                         netmask = 0;
 119                                         msk = 0x80000000;
 120                                         while (netprefix > 0) {
 121                                                 netmask |= msk;
 122                                                 msk >>= 1;
 123                                                 netprefix--;
 124                                         }
 125                                         netmask = htonl(netmask);
 126                                         /* Even if it was 0, we will signify that we have a netmask. This allows */
 127                                         /* for specification of default routes, etc which have a 0 netmask/prefix */
 128                                         have_netmask = 1;
 129                                 }
 130                                 break;
 131                         }
 132                         prefixstr++;
 133                 }
 134         }
 135         ipaddr = inet_aton(ipstr, &a);
 136
 137         if (ipaddr == 0) {
 138                 bb_error_msg_and_die("bad IP address: %s", argv[0]);
 139         }
 140         ipaddr = a.s_addr;
 141
 142         if (argc == 2) {
 143                 if (ENABLE_FEATURE_IPCALC_FANCY && have_netmask) {
 144                         bb_error_msg_and_die("use prefix or netmask, not both");
 145                 }
 146
 147                 netmask = inet_aton(argv[1], &a);
 148                 if (netmask == 0) {
 149                         bb_error_msg_and_die("bad netmask: %s", argv[1]);
 150                 }
 151                 netmask = a.s_addr;
 152         } else {
 153
 154                 /* JHC - If the netmask wasn't provided then calculate it */
 155                 if (!ENABLE_FEATURE_IPCALC_FANCY || !have_netmask)
 156                         netmask = get_netmask(ipaddr);
 157         }
 158
 159         if (opt & NETMASK) {
 160                 printf("NETMASK=%s\n", inet_ntoa((*(struct in_addr *) &netmask)));
 161         }
 162
 163         if (opt & BROADCAST) {
 164                 broadcast = (ipaddr & netmask) | ~netmask;
 165                 printf("BROADCAST=%s\n", inet_ntoa((*(struct in_addr *) &broadcast)));
 166         }
 167
 168         if (opt & NETWORK) {
 169                 network = ipaddr & netmask;
 170                 printf("NETWORK=%s\n", inet_ntoa((*(struct in_addr *) &network)));
 171         }
 172
 173         if (ENABLE_FEATURE_IPCALC_FANCY) {
 174                 if (opt & NETPREFIX) {
 175                         printf("PREFIX=%i\n", get_prefix(netmask));
 176                 }
 177
 178                 if (opt & HOSTNAME) {
 179                         struct hostent *hostinfo;
 180                         int x;
 181
 182                         hostinfo = gethostbyaddr((char *) &ipaddr, sizeof(ipaddr), AF_INET);
 183                         if (!hostinfo) {
 184                                 bb_herror_msg_and_die("cannot find hostname for %s", argv[0]);
 185                         }
 186                         for (x = 0; hostinfo->h_name[x]; x++) {
 187                                 hostinfo->h_name[x] = tolower(hostinfo->h_name[x]);
 188                         }
 189
 190                         printf("HOSTNAME=%s\n", hostinfo->h_name);
 191                 }
 192         }
 193
 194         return EXIT_SUCCESS;
 195 }