/* 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 tarball for details.
*/
#include "busybox.h"
#include <ctype.h>
#include <getopt.h>
#include <sys/socket.h>
#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;
}
#ifdef CONFIG_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 struct option long_options[] = {
    { "netmask",     no_argument, NULL, ‘m‘ },
    { "broadcast",   no_argument, NULL, ‘b‘ },
    { "network",     no_argument, NULL, ‘n‘ },
# if ENABLE_FEATURE_IPCALC_FANCY
    { "prefix",      no_argument, NULL, ‘p‘ },
    { "hostname",     no_argument, NULL, ‘h‘ },
    { "silent",      no_argument, NULL, ‘s‘ },
# endif
    { NULL, 0, NULL, 0 }
};
#endif
int ipcalc_main(int argc, char **argv)
{
    unsigned opt;
    int have_netmask = 0;
    in_addr_t netmask, broadcast, network, ipaddr;
    struct in_addr a;
    char *ipstr;
#if ENABLE_FEATURE_IPCALC_LONG_OPTIONS
    applet_long_options = long_options;
#endif
    opt = getopt32(argc, argv, "mbn" USE_FEATURE_IPCALC_FANCY("phs"));
    argc -= optind;
    argv += optind;
    if (opt & (BROADCAST | NETWORK | NETPREFIX)) {
        if (argc > 2 || argc <= 0)
            bb_show_usage();
    } else {
        if (argc != 1)
            bb_show_usage();
    }
    if (opt & SILENT)
        logmode = LOGMODE_NONE; /* Suppress error_msg() output */
    ipstr = argv[0];
    if (ENABLE_FEATURE_IPCALC_FANCY) {
        unsigned long netprefix = 0;
        char *prefixstr;
        prefixstr = ipstr;
        while (*prefixstr) {
            if (*prefixstr == ‘/‘) {
                *prefixstr = (char)0;
                prefixstr++;
                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++;
        }
    }
    ipaddr = inet_aton(ipstr, &a);
    if (ipaddr == 0) {
        bb_error_msg_and_die("bad IP address: %s", argv[0]);
    }
    ipaddr = a.s_addr;
    if (argc == 2) {
        if (ENABLE_FEATURE_IPCALC_FANCY && have_netmask) {
            bb_error_msg_and_die("use prefix or netmask, not both");
        }
        netmask = inet_aton(argv[1], &a);
        if (netmask == 0) {
            bb_error_msg_and_die("bad netmask: %s", argv[1]);
        }
        netmask = a.s_addr;
    } 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=%sn", inet_ntoa((*(struct in_addr *) &netmask)));
    }
    if (opt & BROADCAST) {
        broadcast = (ipaddr & netmask) | ~netmask;
        printf("BROADCAST=%sn", inet_ntoa((*(struct in_addr *) &broadcast)));
    }
    if (opt & NETWORK) {
        network = ipaddr & netmask;
        printf("NETWORK=%sn", inet_ntoa((*(struct in_addr *) &network)));
    }
    if (ENABLE_FEATURE_IPCALC_FANCY) {
        if (opt & NETPREFIX) {
            printf("PREFIX=%in", get_prefix(netmask));
        }
        if (opt & HOSTNAME) {
            struct hostent *hostinfo;
            int x;
            hostinfo = gethostbyaddr((char *) &ipaddr, sizeof(ipaddr), AF_INET);
            if (!hostinfo) {
                bb_herror_msg_and_die("cannot find hostname for %s", argv[0]);
            }
            for (x = 0; hostinfo->h_name[x]; x++) {
                hostinfo->h_name[x] = tolower(hostinfo->h_name[x]);
            }
            printf("HOSTNAME=%sn", hostinfo->h_name);
        }
    }
    return EXIT_SUCCESS;
}