source: MondoRescue/branches/3.0/mindi-busybox/networking/ipcalc.c@ 3085

/* vi: set sw=4 ts=4: */
/*
 * Mini ipcalc implementation for busybox
 *
 * By Jordan Crouse <jordan@cosmicpenguin.net>
 *    Stephan Linz  <linz@li-pro.net>
 *
 * This is a complete reimplementation of the ipcalc program
 * from Red Hat.  I didn't look at their source code, but there
 * is no denying that this is a loving reimplementation
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include "libbb.h"
/* After libbb.h, because on some systems it needs other includes */
#include <arpa/inet.h>

#define CLASS_A_NETMASK ntohl(0xFF000000)
#define CLASS_B_NETMASK ntohl(0xFFFF0000)
#define CLASS_C_NETMASK ntohl(0xFFFFFF00)

static unsigned long get_netmask(unsigned long ipaddr)
{
    ipaddr = htonl(ipaddr);

    if ((ipaddr & 0xC0000000) == 0xC0000000)
        return CLASS_C_NETMASK;
    else if ((ipaddr & 0x80000000) == 0x80000000)
        return CLASS_B_NETMASK;
    else if ((ipaddr & 0x80000000) == 0)
        return CLASS_A_NETMASK;
    else
        return 0;
}

#if ENABLE_FEATURE_IPCALC_FANCY
static int get_prefix(unsigned long netmask)
{
    unsigned long msk = 0x80000000;
    int ret = 0;

    netmask = htonl(netmask);
    while (msk) {
        if (netmask & msk)
            ret++;
        msk >>= 1;
    }
    return ret;
}
#else
int get_prefix(unsigned long netmask);
#endif


#define NETMASK   0x01
#define BROADCAST 0x02
#define NETWORK   0x04
#define NETPREFIX 0x08
#define HOSTNAME  0x10
#define SILENT    0x20

#if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
    static const char ipcalc_longopts[] ALIGN1 =
        "netmask\0"   No_argument "m" // netmask from IP (assuming complete class A, B, or C network)
        "broadcast\0" No_argument "b" // broadcast from IP [netmask]
        "network\0"   No_argument "n" // network from IP [netmask]
# if ENABLE_FEATURE_IPCALC_FANCY
        "prefix\0"    No_argument "p" // prefix from IP[/prefix] [netmask]
        "hostname\0"  No_argument "h" // hostname from IP
        "silent\0"    No_argument "s" // don’t ever display error messages
# endif
        ;
#endif

int ipcalc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ipcalc_main(int argc UNUSED_PARAM, char **argv)
{
    unsigned opt;
    bool have_netmask = 0;
    struct in_addr s_netmask, s_broadcast, s_network, s_ipaddr;
    /* struct in_addr { in_addr_t s_addr; }  and  in_addr_t
     * (which in turn is just a typedef to uint32_t)
     * are essentially the same type. A few macros for less verbosity: */
#define netmask   (s_netmask.s_addr)
#define broadcast (s_broadcast.s_addr)
#define network   (s_network.s_addr)
#define ipaddr    (s_ipaddr.s_addr)
    char *ipstr;

#if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
    applet_long_options = ipcalc_longopts;
#endif
    opt_complementary = "-1:?2"; /* minimum 1 arg, maximum 2 args */
    opt = getopt32(argv, "mbn" IF_FEATURE_IPCALC_FANCY("phs"));
    argv += optind;
    if (opt & SILENT)
        logmode = LOGMODE_NONE; /* suppress error_msg() output */
    opt &= ~SILENT;
    if (!(opt & (BROADCAST | NETWORK | NETPREFIX))) {
        /* if no options at all or
         * (no broadcast,network,prefix) and (two args)... */
        if (!opt || argv[1])
            bb_show_usage();
    }

    ipstr = argv[0];
    if (ENABLE_FEATURE_IPCALC_FANCY) {
        unsigned long netprefix = 0;
        char *prefixstr;

        prefixstr = ipstr;

        while (*prefixstr) {
            if (*prefixstr == '/') {
                *prefixstr++ = '\0';
                if (*prefixstr) {
                    unsigned msk;
                    netprefix = xatoul_range(prefixstr, 0, 32);
                    netmask = 0;
                    msk = 0x80000000;
                    while (netprefix > 0) {
                        netmask |= msk;
                        msk >>= 1;
                        netprefix--;
                    }
                    netmask = htonl(netmask);
                    /* Even if it was 0, we will signify that we have a netmask. This allows */
                    /* for specification of default routes, etc which have a 0 netmask/prefix */
                    have_netmask = 1;
                }
                break;
            }
            prefixstr++;
        }
    }

    if (inet_aton(ipstr, &s_ipaddr) == 0) {
        bb_error_msg_and_die("bad IP address: %s", argv[0]);
    }

    if (argv[1]) {
        if (ENABLE_FEATURE_IPCALC_FANCY && have_netmask) {
            bb_error_msg_and_die("use prefix or netmask, not both");
        }
        if (inet_aton(argv[1], &s_netmask) == 0) {
            bb_error_msg_and_die("bad netmask: %s", argv[1]);
        }
    } else {
        /* JHC - If the netmask wasn't provided then calculate it */
        if (!ENABLE_FEATURE_IPCALC_FANCY || !have_netmask)
            netmask = get_netmask(ipaddr);
    }

    if (opt & NETMASK) {
        printf("NETMASK=%s\n", inet_ntoa(s_netmask));
    }

    if (opt & BROADCAST) {
        broadcast = (ipaddr & netmask) | ~netmask;
        printf("BROADCAST=%s\n", inet_ntoa(s_broadcast));
    }

    if (opt & NETWORK) {
        network = ipaddr & netmask;
        printf("NETWORK=%s\n", inet_ntoa(s_network));
    }

    if (ENABLE_FEATURE_IPCALC_FANCY) {
        if (opt & NETPREFIX) {
            printf("PREFIX=%i\n", get_prefix(netmask));
        }

        if (opt & HOSTNAME) {
            struct hostent *hostinfo;

            hostinfo = gethostbyaddr((char *) &ipaddr, sizeof(ipaddr), AF_INET);
            if (!hostinfo) {
                bb_herror_msg_and_die("can't find hostname for %s", argv[0]);
            }
            str_tolower(hostinfo->h_name);

            printf("HOSTNAME=%s\n", hostinfo->h_name);
        }
    }

    return EXIT_SUCCESS;
}