/*
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#) Copyright (c) 1988, 1993 The Regents of the University of California.  All rights reserved.
 * @(#)hostname.c       8.1 (Berkeley) 5/31/93
 * $FreeBSD: src/bin/hostname/hostname.c,v 1.10.2.1 2001/08/01 02:40:23 obrien Exp $
 */

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/module.h>
#include <sys/linker.h>

#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <netinet/in.h>

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <netdb.h>
#include <sys/types.h>
#include <arpa/inet.h>

#include <errno.h>

#define HST_IF    (1 << 0)
#define HST_IF_V6 (1 << 1)
#define HST_IF_V4 (1 << 2)

/*
 * Expand the compacted form of addresses as returned via the
 * configuration read via sysctl().
 * Lifted from getifaddrs(3)
 */

static void rt_xaddrs(caddr_t, caddr_t, struct rt_addrinfo *);
static void usage (void);

#ifndef RT_ROUNDUP
#define RT_ROUNDUP(a) \
        ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
#endif
#ifndef RT_ADVANCE
#define RT_ADVANCE(x, n) (x += RT_ROUNDUP((n)->sa_len))
#endif

static
void
rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
{
        struct sockaddr *sa;
        int i;

        memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
        for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
                if ((rtinfo->rti_addrs & (1 << i)) == 0)
                        continue;
                rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
                RT_ADVANCE(cp, sa);
        }
}

int
main(int argc, char **argv)
{
        int ch, sflag, rflag, ret, flag6, iflag;
        int silen = 0;
        char hostname[MAXHOSTNAMELEN];
        char *srflag, *siflag;
        struct hostent *hst;
        struct in_addr ia;
        struct in6_addr ia6;

        int mib[6];
        size_t needed;
        char *buf, *next, *p;
        int idx;
        struct sockaddr_dl *sdl;
        struct rt_msghdr *rtm;
        struct if_msghdr *ifm;
        struct ifa_msghdr *ifam;
        struct rt_addrinfo info;
        struct sockaddr_in *sai;
        struct sockaddr_in6 *sai6;

        srflag = NULL;
        siflag = NULL;
        iflag = sflag = rflag = 0;
        flag6 = 0;
        hst = NULL;

        while ((ch = getopt(argc, argv, "46fi:r:s")) != -1) {
                switch (ch) {
                case '4':
                        iflag |= HST_IF_V4;
                        break;
                case '6':
                        iflag |= HST_IF_V6;
                        break;
                case 'f':
                        /* Printing the FQDN is default. */
                        break;
                case 'i':
                        siflag = optarg;
                        silen = strlen(siflag);
                        iflag |= HST_IF;
                        break;
                case 'r':
                        srflag = optarg;
                        rflag = 1;
                        break;
                case 's':
                        sflag = 1;
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (argc > 1)
                usage();

        if (iflag && *argv)
                usage();

        if (rflag && *argv)
                usage();

        if (rflag && (iflag & HST_IF))
                usage();

        if ((iflag & HST_IF_V6) && (iflag & HST_IF_V4))
                usage();

        if (!(iflag & HST_IF) && ((iflag & HST_IF_V6)||iflag & HST_IF_V4))
                usage();

        if (iflag & HST_IF) {
                mib[0] = CTL_NET;
                mib[1] = PF_ROUTE;
                mib[2] = 0;
                mib[3] = 0;
                mib[4] = NET_RT_IFLIST;
                mib[5] = 0;

                idx = 0;
                needed = 1;

                if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
                        err(1, "sysctl: iflist-sysctl-estimate");
                if ((buf = malloc(needed)) == NULL)
                        err(1, "malloc failed");
                if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
                        err(1, "sysctl: retrieval of interface table");
        
                for (next = buf; next < buf + needed; next += rtm->rtm_msglen) {
                        rtm = (struct rt_msghdr *)(void *)next;
                        if (rtm->rtm_version != RTM_VERSION)
                                continue;
                        switch (rtm->rtm_type) {
                        case RTM_IFINFO:
                                ifm = (struct if_msghdr *)(void *)rtm;

                                if ((ifm->ifm_addrs & RTA_IFP) == 0)
                                        break;
                                sdl = (struct sockaddr_dl *)(ifm + 1);
                                if (silen != sdl->sdl_nlen)
                                        break;
                                if (!strncmp(siflag, sdl->sdl_data, silen)) {
                                        idx = ifm->ifm_index;
                                }
                                break;
                        case RTM_NEWADDR:
                                ifam = (struct ifa_msghdr *)(void *)rtm;

                                if (ifam->ifam_index == idx) {
                                        info.rti_addrs = ifam->ifam_addrs;
                                        rt_xaddrs((char *)(ifam + 1),
                                                ifam->ifam_msglen + (char *)ifam, &info);
                                        sai = (struct sockaddr_in *)info.rti_info[RTAX_IFA];

                                        if (iflag & HST_IF_V6) {
                                                if (sai->sin_family == AF_INET6) {
                                                        sai6 = (struct sockaddr_in6 *)info.rti_info[RTAX_IFA];
                                                        hst = gethostbyaddr(&sai6->sin6_addr,
                                                                        sizeof(sai6->sin6_addr),AF_INET6);

                                                        if (h_errno == NETDB_SUCCESS) {
                                                                next = buf + needed;
                                                                continue;
                                                        }
                                                }
                                        } else {
                                                if (sai->sin_family == AF_INET) {

                                                        hst = gethostbyaddr(&sai->sin_addr,
                                                                        sizeof(sai->sin_addr),AF_INET);

                                                        if (h_errno == NETDB_SUCCESS) {
                                                                next = buf + needed;
                                                                continue;
                                                        }
                                                }
                                        }
                                }
                                break;
                        } /* switch */
                } /* loop */

                free(buf);

                if (idx == 0)
                        errx(1,"interface not found");
                if (hst == NULL)
                        errx(1, "ip not found on interface");

                if (h_errno == NETDB_SUCCESS) {
                        if (sethostname(hst->h_name, (int)strlen(hst->h_name)))
                                err(1, "sethostname");
                } else if (h_errno == HOST_NOT_FOUND) {
                        errx(1,"hostname not found");
                } else {
                        herror("gethostbyaddr");
                        exit(1);
                }
        } else if (rflag) {
                ret = inet_pton(AF_INET, srflag, &ia);
                if (ret != 1) {
                        /* check IPV6 */
                        ret = inet_pton(AF_INET6, srflag, &ia6);

                        if (ret != 1) {
                                errx(1, "invalid ip address");
                        }

                        flag6 = 1;
                }
                
                if (flag6 == 1) 
                        hst = gethostbyaddr(&ia6, sizeof(ia6), AF_INET6);
                else
                        hst = gethostbyaddr(&ia, sizeof(ia), AF_INET);
                if (!hst) {
                        if (h_errno == HOST_NOT_FOUND) 
                                errx(1,"host not found\n");
                }

                if (sethostname(hst->h_name, (int)strlen(hst->h_name)))
                        err(1, "sethostname");
        } else if (*argv) {
                if (sethostname(*argv, (int)strlen(*argv)))
                        err(1, "sethostname");
        } else {
                if (gethostname(hostname, (int)sizeof(hostname)))
                        err(1, "gethostname");
                if (sflag && (p = strchr(hostname, '.')))
                        *p = '\0';
                printf("%s\n", hostname);
        }
        exit(0);
}

static void
usage(void)
{
        fprintf(stderr, "usage: hostname [-s] [name-of-host |"
                        " -r ip-address | -i interface [-4 | -6]]\n");
        exit(1);
}