/*
 * Copyright (c) 2016-2017, Marie Helene Kvello-Aune
 * 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,
 * thislist 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.
 *
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
 */

#include <err.h>
#include <errno.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libifconfig.h>


int
main(int argc, char *argv[])
{
        char *ifname, *ptr;
        int mtu;
        ifconfig_handle_t *lifh;

        if (argc != 3) {
                errx(EINVAL, "Invalid number of arguments."
                    " First argument should be interface name, second argument"
                    " should be the MTU to set.");
        }

        /* We have a static number of arguments. Therefore we can do it simple. */
        ifname = strdup(argv[1]);
        mtu = (int)strtol(argv[2], &ptr, 10);

        printf("Interface name: %s\n", ifname);
        printf("New MTU: %d", mtu);

        lifh = ifconfig_open();
        if (lifh == NULL) {
                errx(ENOMEM, "Failed to open libifconfig handle.");
                return (-1);
        }

        if (ifconfig_set_mtu(lifh, ifname, mtu) == 0) {
                printf("Successfully changed MTU of %s to %d\n", ifname, mtu);
                ifconfig_close(lifh);
                lifh = NULL;
                free(ifname);
                return (0);
        }

        switch (ifconfig_err_errtype(lifh)) {
        case SOCKET:
                warnx("couldn't create socket. This shouldn't happen.\n");
                break;
        case IOCTL:
                if (ifconfig_err_ioctlreq(lifh) == SIOCSIFMTU) {
                        warnx("Failed to set MTU (SIOCSIFMTU)\n");
                } else {
                        warnx(
                                "Failed to set MTU due to error in unexpected ioctl() call %lu. Error code: %i.\n",
                                ifconfig_err_ioctlreq(lifh),
                                ifconfig_err_errno(lifh));
                }
                break;
        default:
                warnx(
                        "Should basically never end up here in this example.\n");
                break;
        }

        ifconfig_close(lifh);
        lifh = NULL;
        free(ifname);
        return (-1);
}