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 <sys/socket.h>
  16 #include <arpa/inet.h>
  17
  18 #include "libbb.h"
  19
  20 #define CLASS_A_NETMASK ntohl(0xFF000000)
  21 #define CLASS_B_NETMASK ntohl(0xFFFF0000)
  22 #define CLASS_C_NETMASK ntohl(0xFFFFFF00)
  23
  24 static unsigned long get_netmask(unsigned long ipaddr)
  25 {
  26         ipaddr = htonl(ipaddr);
  27
  28         if ((ipaddr & 0xC0000000) == 0xC0000000)
  29                 return CLASS_C_NETMASK;
  30         else if ((ipaddr & 0x80000000) == 0x80000000)
  31                 return CLASS_B_NETMASK;
  32         else if ((ipaddr & 0x80000000) == 0)
  33                 return CLASS_A_NETMASK;
  34         else
  35                 return 0;
  36 }
  37
  38 #if ENABLE_FEATURE_IPCALC_FANCY
  39 static int get_prefix(unsigned long netmask)
  40 {
  41         unsigned long msk = 0x80000000;
  42         int ret = 0;
  43
  44         netmask = htonl(netmask);
  45         while (msk) {
  46                 if (netmask & msk)
  47                         ret++;
  48                 msk >>= 1;
  49         }
  50         return ret;
  51 }
  52 #else
  53 int get_prefix(unsigned long netmask);
  54 #endif
  55
  56
  57 #define NETMASK   0x01
  58 #define BROADCAST 0x02
  59 #define NETWORK   0x04
  60 #define NETPREFIX 0x08
  61 #define HOSTNAME  0x10
  62 #define SILENT    0x20
  63
  64 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
  65         static const char ipcalc_longopts[] ALIGN1 =
  66                 "netmask\0"   No_argument "m"
  67                 "broadcast\0" No_argument "b"
  68                 "network\0"   No_argument "n"
  69 # if ENABLE_FEATURE_IPCALC_FANCY
  70                 "prefix\0"    No_argument "p"
  71                 "hostname\0"  No_argument "h"
  72                 "silent\0"    No_argument "s"
  73 # endif
  74                 ;
  75 #endif
  76
  77 int ipcalc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  78 int ipcalc_main(int argc UNUSED_PARAM, char **argv)
  79 {
  80         unsigned opt;
  81         bool have_netmask = 0;
  82         struct in_addr s_netmask, s_broadcast, s_network, s_ipaddr;
  83         /* struct in_addr { in_addr_t s_addr; }  and  in_addr_t
  84          * (which in turn is just a typedef to uint32_t)
  85          * are essentially the same type. A few macros for less verbosity: */
  86 #define netmask   (s_netmask.s_addr)
  87 #define broadcast (s_broadcast.s_addr)
  88 #define network   (s_network.s_addr)
  89 #define ipaddr    (s_ipaddr.s_addr)
  90         char *ipstr;
  91
  92 #if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
  93         applet_long_options = ipcalc_longopts;
  94 #endif
  95         opt = getopt32(argv, "mbn" IF_FEATURE_IPCALC_FANCY("phs"));
  96         argv += optind;
  97         if (opt & SILENT)
  98                 logmode = LOGMODE_NONE; /* suppress error_msg() output */
  99         if (opt & (BROADCAST | NETWORK | NETPREFIX)) {
 100                 if (!argv[0] || !argv[1] || argv[2])
 101                         bb_show_usage();
 102         } else {
 103                 if (!argv[0] || argv[1])
 104                         bb_show_usage();
 105         }
 106
 107         ipstr = argv[0];
 108         if (ENABLE_FEATURE_IPCALC_FANCY) {
 109                 unsigned long netprefix = 0;
 110                 char *prefixstr;
 111
 112                 prefixstr = ipstr;
 113
 114                 while (*prefixstr) {
 115                         if (*prefixstr == '/') {
 116                                 *prefixstr++ = '\0';
 117                                 if (*prefixstr) {
 118                                         unsigned msk;
 119                                         netprefix = xatoul_range(prefixstr, 0, 32);
 120                                         netmask = 0;
 121                                         msk = 0x80000000;
 122                                         while (netprefix > 0) {
 123                                                 netmask |= msk;
 124                                                 msk >>= 1;
 125                                                 netprefix--;
 126                                         }
 127                                         netmask = htonl(netmask);
 128                                         /* Even if it was 0, we will signify that we have a netmask. This allows */
 129                                         /* for specification of default routes, etc which have a 0 netmask/prefix */
 130                                         have_netmask = 1;
 131                                 }
 132                                 break;
 133                         }
 134                         prefixstr++;
 135                 }
 136         }
 137
 138         if (inet_aton(ipstr, &s_ipaddr) == 0) {
 139                 bb_error_msg_and_die("bad IP address: %s", argv[0]);
 140         }
 141
 142         if (argv[1]) {
 143                 if (ENABLE_FEATURE_IPCALC_FANCY && have_netmask) {
 144                         bb_error_msg_and_die("use prefix or netmask, not both");
 145                 }
 146                 if (inet_aton(argv[1], &s_netmask) == 0) {
 147                         bb_error_msg_and_die("bad netmask: %s", argv[1]);
 148                 }
 149         } else {
 150                 /* JHC - If the netmask wasn't provided then calculate it */
 151                 if (!ENABLE_FEATURE_IPCALC_FANCY || !have_netmask)
 152                         netmask = get_netmask(ipaddr);
 153         }
 154
 155         if (opt & NETMASK) {
 156                 printf("NETMASK=%s\n", inet_ntoa(s_netmask));
 157         }
 158
 159         if (opt & BROADCAST) {
 160                 broadcast = (ipaddr & netmask) | ~netmask;
 161                 printf("BROADCAST=%s\n", inet_ntoa(s_broadcast));
 162         }
 163
 164         if (opt & NETWORK) {
 165                 network = ipaddr & netmask;
 166                 printf("NETWORK=%s\n", inet_ntoa(s_network));
 167         }
 168
 169         if (ENABLE_FEATURE_IPCALC_FANCY) {
 170                 if (opt & NETPREFIX) {
 171                         printf("PREFIX=%i\n", get_prefix(netmask));
 172                 }
 173
 174                 if (opt & HOSTNAME) {
 175                         struct hostent *hostinfo;
 176
 177                         hostinfo = gethostbyaddr((char *) &ipaddr, sizeof(ipaddr), AF_INET);
 178                         if (!hostinfo) {
 179                                 bb_herror_msg_and_die("can't find hostname for %s", argv[0]);
 180                         }
 181                         str_tolower(hostinfo->h_name);
 182
 183                         printf("HOSTNAME=%s\n", hostinfo->h_name);
 184                 }
 185         }
 186
 187         return EXIT_SUCCESS;
 188 }