usb_moded-mac.c

/**
 * @file usb_moded-mac.c
 *
 * Copyright (C) 2013-2018 Jolla. All rights reserved.
 *
 * @author: Philippe De Swert <philippe.deswert@jollamobile.com>
 * @author: Simo Piiroinen <simo.piiroinen@jollamobile.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the Lesser GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the Lesser GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include "usb_moded-mac.h"

#include "usb_moded-log.h"

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

/* ========================================================================= *
 * Prototypes
 * ========================================================================= */

/* -- mac -- */

static void  mac_random_ether_addr  (unsigned char *addr);
void         mac_generate_random_mac(void);
char        *mac_read_mac           (void);

/* ========================================================================= *
 * Functions
 * ========================================================================= */

static void mac_random_ether_addr(unsigned char *addr)
{
    FILE *random;
    size_t count = 0;

    random = fopen("/dev/urandom", "r");
    count = fread(addr, 1, 6, random);
    fclose(random);

    if(count > 0 )
    {
        addr [0] &= 0xfe;       /* clear multicast bit */
        addr [0] |= 0x02;       /* set local assignment bit (IEEE802) */
    }
    else
        log_warning("MAC generation failed!\n");
}

void mac_generate_random_mac (void)
{
    unsigned char addr[6];
    int i;
    FILE *g_ether;

    log_debug("Getting random usb ethernet mac\n");
    mac_random_ether_addr(addr);

    g_ether = fopen("/etc/modprobe.d/g_ether.conf", "w");
    if(!g_ether)
    {
        log_warning("Failed to write mac address to /etc/modprobe.d/g_ether.conf\n");
        return;
    }
    fprintf(g_ether, "options g_ether host_addr=");

    for(i=0; i<5; i++)
    {
        fprintf(g_ether, "%02x:",addr[i]);
    }
    fprintf(g_ether, "%02x\n",addr[i]);
    fclose(g_ether);
}

char * mac_read_mac(void)
{
    FILE *g_ether;
    char *mac = NULL, *ret = NULL;
    size_t read = 0;
    int test = 0;

    g_ether = fopen("/etc/modprobe.d/g_ether.conf", "r");
    if(!g_ether)
    {
        log_warning("Failed to read mac address from /etc/modprobe.d/g_ether.conf\n");
        return NULL;
    }
    test = fseek(g_ether, 26, SEEK_SET);
    if(test == -1)
    {
        fclose(g_ether);
        return 0;
    }
    mac = malloc(17);
    if(mac)
        read = fread(mac, 1, 17, g_ether);
    if(read == 17)
        ret = strndup(mac,17);
    else
        ret = 0;

    free(mac);
    fclose(g_ether);
    return ret;
}