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 source tree.
  13  */
  14
  15 //usage:#define ipcalc_trivial_usage
  16 //usage:       "[OPTIONS] ADDRESS[[/]NETMASK] [NETMASK]"
  17 //usage:#define ipcalc_full_usage "\n\n"
  18 //usage:       "Calculate IP network settings from a IP address\n"
  19 //usage:        IF_FEATURE_IPCALC_LONG_OPTIONS(
  20 //usage:     "\n        -b,--broadcast  Display calculated broadcast address"
  21 //usage:     "\n        -n,--network    Display calculated network address"
  22 //usage:     "\n        -m,--netmask    Display default netmask for IP"
  23 //usage:        IF_FEATURE_IPCALC_FANCY(
  24 //usage:     "\n        -p,--prefix     Display the prefix for IP/NETMASK"
  25 //usage:     "\n        -h,--hostname   Display first resolved host name"
  26 //usage:     "\n        -s,--silent     Don't ever display error messages"
  27 //usage:        )
  28 //usage:        )
  29 //usage:        IF_NOT_FEATURE_IPCALC_LONG_OPTIONS(
  30 //usage:     "\n        -b      Display calculated broadcast address"
  31 //usage:     "\n        -n      Display calculated network address"
  32 //usage:     "\n        -m      Display default netmask for IP"
  33 //usage:        IF_FEATURE_IPCALC_FANCY(
  34 //usage:     "\n        -p      Display the prefix for IP/NETMASK"
  35 //usage:     "\n        -h      Display first resolved host name"
  36 //usage:     "\n        -s      Don't ever display error messages"
  37 //usage:        )
  38 //usage:        )
  39
  40 #include "libbb.h"
  41 /* After libbb.h, because on some systems it needs other includes */
  42 #include <arpa/inet.h>
  43
  44 #define CLASS_A_NETMASK ntohl(0xFF000000)
  45 #define CLASS_B_NETMASK ntohl(0xFFFF0000)
  46 #define CLASS_C_NETMASK ntohl(0xFFFFFF00)
  47
  48 static unsigned long get_netmask(unsigned long ipaddr)
  49 {
  50         ipaddr = htonl(ipaddr);
  51
  52         if ((ipaddr & 0xC0000000) == 0xC0000000)
  53                 return CLASS_C_NETMASK;
  54         else if ((ipaddr & 0x80000000) == 0x80000000)
  55                 return CLASS_B_NETMASK;
  56         else if ((ipaddr & 0x80000000) == 0)
  57                 return CLASS_A_NETMASK;
  58         else
  59                 return 0;
  60 }
  61
  62 #if ENABLE_FEATURE_IPCALC_FANCY
  63 static int get_prefix(unsigned long netmask)
  64 {
  65         unsigned long msk = 0x80000000;
  66         int ret = 0;
  67
  68         netmask = htonl(netmask);
  69         while (msk) {
  70                 if (netmask & msk)
  71                         ret++;
  72                 msk >>= 1;
  73         }
  74         return ret;
  75 }
  76 #else
  77 int get_prefix(unsigned long netmask);
  78 #endif
  79
  80
  81 #define NETMASK   0x01
  82 #define BROADCAST 0x02
  83 #define NETWORK   0x04
  84 #define NETPREFIX 0x08
  85 #define HOSTNAME  0x10
  86 #define SILENT    0x20
  87
  88 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
  89         static const char ipcalc_longopts[] ALIGN1 =
  90                 "netmask\0"   No_argument "m" // netmask from IP (assuming complete class A, B, or C network)
  91                 "broadcast\0" No_argument "b" // broadcast from IP [netmask]
  92                 "network\0"   No_argument "n" // network from IP [netmask]
  93 # if ENABLE_FEATURE_IPCALC_FANCY
  94                 "prefix\0"    No_argument "p" // prefix from IP[/prefix] [netmask]
  95                 "hostname\0"  No_argument "h" // hostname from IP
  96                 "silent\0"    No_argument "s" // don’t ever display error messages
  97 # endif
  98                 ;
  99 #endif
 100
 101 int ipcalc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 102 int ipcalc_main(int argc UNUSED_PARAM, char **argv)
 103 {
 104         unsigned opt;
 105         bool have_netmask = 0;
 106         struct in_addr s_netmask, s_broadcast, s_network, s_ipaddr;
 107         /* struct in_addr { in_addr_t s_addr; }  and  in_addr_t
 108          * (which in turn is just a typedef to uint32_t)
 109          * are essentially the same type. A few macros for less verbosity: */
 110 #define netmask   (s_netmask.s_addr)
 111 #define broadcast (s_broadcast.s_addr)
 112 #define network   (s_network.s_addr)
 113 #define ipaddr    (s_ipaddr.s_addr)
 114         char *ipstr;
 115
 116 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
 117         applet_long_options = ipcalc_longopts;
 118 #endif
 119         opt_complementary = "-1:?2"; /* minimum 1 arg, maximum 2 args */
 120         opt = getopt32(argv, "mbn" IF_FEATURE_IPCALC_FANCY("phs"));
 121         argv += optind;
 122         if (opt & SILENT)
 123                 logmode = LOGMODE_NONE; /* suppress error_msg() output */
 124         opt &= ~SILENT;
 125         if (!(opt & (BROADCAST | NETWORK | NETPREFIX))) {
 126                 /* if no options at all or
 127                  * (no broadcast,network,prefix) and (two args)... */
 128                 if (!opt || argv[1])
 129                         bb_show_usage();
 130         }
 131
 132         ipstr = argv[0];
 133         if (ENABLE_FEATURE_IPCALC_FANCY) {
 134                 unsigned long netprefix = 0;
 135                 char *prefixstr;
 136
 137                 prefixstr = ipstr;
 138
 139                 while (*prefixstr) {
 140                         if (*prefixstr == '/') {
 141                                 *prefixstr++ = '\0';
 142                                 if (*prefixstr) {
 143                                         unsigned msk;
 144                                         netprefix = xatoul_range(prefixstr, 0, 32);
 145                                         netmask = 0;
 146                                         msk = 0x80000000;
 147                                         while (netprefix > 0) {
 148                                                 netmask |= msk;
 149                                                 msk >>= 1;
 150                                                 netprefix--;
 151                                         }
 152                                         netmask = htonl(netmask);
 153                                         /* Even if it was 0, we will signify that we have a netmask. This allows */
 154                                         /* for specification of default routes, etc which have a 0 netmask/prefix */
 155                                         have_netmask = 1;
 156                                 }
 157                                 break;
 158                         }
 159                         prefixstr++;
 160                 }
 161         }
 162
 163         if (inet_aton(ipstr, &s_ipaddr) == 0) {
 164                 bb_error_msg_and_die("bad IP address: %s", argv[0]);
 165         }
 166
 167         if (argv[1]) {
 168                 if (ENABLE_FEATURE_IPCALC_FANCY && have_netmask) {
 169                         bb_error_msg_and_die("use prefix or netmask, not both");
 170                 }
 171                 if (inet_aton(argv[1], &s_netmask) == 0) {
 172                         bb_error_msg_and_die("bad netmask: %s", argv[1]);
 173                 }
 174         } else {
 175                 /* JHC - If the netmask wasn't provided then calculate it */
 176                 if (!ENABLE_FEATURE_IPCALC_FANCY || !have_netmask)
 177                         netmask = get_netmask(ipaddr);
 178         }
 179
 180         if (opt & NETMASK) {
 181                 printf("NETMASK=%s\n", inet_ntoa(s_netmask));
 182         }
 183
 184         if (opt & BROADCAST) {
 185                 broadcast = (ipaddr & netmask) | ~netmask;
 186                 printf("BROADCAST=%s\n", inet_ntoa(s_broadcast));
 187         }
 188
 189         if (opt & NETWORK) {
 190                 network = ipaddr & netmask;
 191                 printf("NETWORK=%s\n", inet_ntoa(s_network));
 192         }
 193
 194         if (ENABLE_FEATURE_IPCALC_FANCY) {
 195                 if (opt & NETPREFIX) {
 196                         printf("PREFIX=%i\n", get_prefix(netmask));
 197                 }
 198
 199                 if (opt & HOSTNAME) {
 200                         struct hostent *hostinfo;
 201
 202                         hostinfo = gethostbyaddr((char *) &ipaddr, sizeof(ipaddr), AF_INET);
 203                         if (!hostinfo) {
 204                                 bb_herror_msg_and_die("can't find hostname for %s", argv[0]);
 205                         }
 206                         str_tolower(hostinfo->h_name);
 207
 208                         printf("HOSTNAME=%s\n", hostinfo->h_name);
 209                 }
 210         }
 211
 212         return EXIT_SUCCESS;
 213 }