source: MondoRescue/branches/stable/mindi-busybox/networking/ether-wake.c

/* vi: set sw=4 ts=4: */
/*
 * ether-wake.c - Send a magic packet to wake up sleeping machines.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 * Author:      Donald Becker, http://www.scyld.com/"; http://www.scyld.com/wakeonlan.html
 * Busybox port: Christian Volkmann <haveaniceday@online.de>
 *               Used version of ether-wake.c: v1.09 11/12/2003 Donald Becker, http://www.scyld.com/";
 */

/* full usage according Donald Becker
 * usage: ether-wake [-i <ifname>] [-p aa:bb:cc:dd[:ee:ff]] 00:11:22:33:44:55\n"
 *
 *  This program generates and transmits a Wake-On-LAN (WOL)\n"
 *  \"Magic Packet\", used for restarting machines that have been\n"
 *  soft-powered-down (ACPI D3-warm state).\n"
 *  It currently generates the standard AMD Magic Packet format, with\n"
 *  an optional password appended.\n"
 *
 *  The single required parameter is the Ethernet MAC (station) address\n"
 *  of the machine to wake or a host ID with known NSS 'ethers' entry.\n"
 *  The MAC address may be found with the 'arp' program while the target\n"
 *  machine is awake.\n"
 *
 *  Options:\n"
 *      -b  Send wake-up packet to the broadcast address.\n"
 *      -D  Increase the debug level.\n"
 *      -i ifname   Use interface IFNAME instead of the default 'eth0'.\n"
 *      -p <pw>     Append the four or six byte password PW to the packet.\n"
 *                  A password is only required for a few adapter types.\n"
 *                  The password may be specified in ethernet hex format\n"
 *                  or dotted decimal (Internet address)\n"
 *      -p 00:22:44:66:88:aa\n"
 *      -p 192.168.1.1\n";
 *
 *
 *  This program generates and transmits a Wake-On-LAN (WOL) "Magic Packet",
 *  used for restarting machines that have been soft-powered-down
 *  (ACPI D3-warm state).  It currently generates the standard AMD Magic Packet
 *  format, with an optional password appended.
 *
 *  This software may be used and distributed according to the terms
 *  of the GNU Public License, incorporated herein by reference.
 *  Contact the author for use under other terms.
 *
 *  This source file was originally part of the network tricks package, and
 *  is now distributed to support the Scyld Beowulf system.
 *  Copyright 1999-2003 Donald Becker and Scyld Computing Corporation.
 *
 *  The author may be reached as becker@scyld, or C/O
 *   Scyld Computing Corporation
 *   914 Bay Ridge Road, Suite 220
 *   Annapolis MD 21403
 *
 *   Notes:
 *   On some systems dropping root capability allows the process to be
 *   dumped, traced or debugged.
 *   If someone traces this program, they get control of a raw socket.
 *   Linux handles this safely, but beware when porting this program.
 *
 *   An alternative to needing 'root' is using a UDP broadcast socket, however
 *   doing so only works with adapters configured for unicast+broadcast Rx
 *   filter.  That configuration consumes more power.
*/


#include <netpacket/packet.h>
#include <net/ethernet.h>
#include <netinet/ether.h>
#include <linux/if.h>

#include "libbb.h"

/* Note: PF_INET, SOCK_DGRAM, IPPROTO_UDP would allow SIOCGIFHWADDR to
 * work as non-root, but we need SOCK_PACKET to specify the Ethernet
 * destination address.
 */
#ifdef PF_PACKET
# define whereto_t sockaddr_ll
# define make_socket() xsocket(PF_PACKET, SOCK_RAW, 0)
#else
# define whereto_t sockaddr
# define make_socket() xsocket(AF_INET, SOCK_PACKET, SOCK_PACKET)
#endif

#ifdef DEBUG
# define bb_debug_msg(fmt, args...) fprintf(stderr, fmt, ## args)
void bb_debug_dump_packet(unsigned char *outpack, int pktsize)
{
    int i;
    printf("packet dump:\n");
    for (i = 0; i < pktsize; ++i) {
        printf("%2.2x ", outpack[i]);
        if (i % 20 == 19) puts("");
    }
    printf("\n\n");
}
#else
# define bb_debug_msg(fmt, args...)             ((void)0)
# define bb_debug_dump_packet(outpack, pktsize) ((void)0)
#endif

/* Convert the host ID string to a MAC address.
 * The string may be a:
 *    Host name
 *    IP address string
 *    MAC address string
*/
static void get_dest_addr(const char *hostid, struct ether_addr *eaddr)
{
    struct ether_addr *eap;

    eap = ether_aton(hostid);
    if (eap) {
        *eaddr = *eap;
        bb_debug_msg("The target station address is %s\n\n", ether_ntoa(eaddr));
#if !defined(__UCLIBC__)
    } else if (ether_hostton(hostid, eaddr) == 0) {
        bb_debug_msg("Station address for hostname %s is %s\n\n", hostid, ether_ntoa(eaddr));
#endif
    } else
        bb_show_usage();
}

static int get_fill(unsigned char *pkt, struct ether_addr *eaddr, int broadcast)
{
    int i;
    unsigned char *station_addr = eaddr->ether_addr_octet;

    memset(pkt, 0xff, 6);
    if (!broadcast)
        memcpy(pkt, station_addr, 6);
    pkt += 6;

    memcpy(pkt, station_addr, 6); /* 6 */
    pkt += 6;

    *pkt++ = 0x08; /* 12 */ /* Or 0x0806 for ARP, 0x8035 for RARP */
    *pkt++ = 0x42; /* 13 */

    memset(pkt, 0xff, 6); /* 14 */

    for (i = 0; i < 16; ++i) {
        pkt += 6;
        memcpy(pkt, station_addr, 6); /* 20,26,32,... */
    }

    return 20 + 16*6; /* length of packet */
}

static int get_wol_pw(const char *ethoptarg, unsigned char *wol_passwd)
{
    unsigned passwd[6];
    int byte_cnt, i;

    /* handle MAC format */
    byte_cnt = sscanf(ethoptarg, "%2x:%2x:%2x:%2x:%2x:%2x",
                      &passwd[0], &passwd[1], &passwd[2],
                      &passwd[3], &passwd[4], &passwd[5]);
    /* handle IP format */
// FIXME: why < 4?? should it be < 6?
    if (byte_cnt < 4)
        byte_cnt = sscanf(ethoptarg, "%u.%u.%u.%u",
                          &passwd[0], &passwd[1], &passwd[2], &passwd[3]);
    if (byte_cnt < 4) {
        bb_error_msg("cannot read Wake-On-LAN pass");
        return 0;
    }
// TODO: check invalid numbers >255??
    for (i = 0; i < byte_cnt; ++i)
        wol_passwd[i] = passwd[i];

    bb_debug_msg("password: %2.2x %2.2x %2.2x %2.2x (%d)\n\n",
                 wol_passwd[0], wol_passwd[1], wol_passwd[2], wol_passwd[3],
                 byte_cnt);

    return byte_cnt;
}

int ether_wake_main(int argc, char **argv);
int ether_wake_main(int argc, char **argv)
{
    const char *ifname = "eth0";
    char *pass;
    unsigned flags;
    unsigned char wol_passwd[6];
    int wol_passwd_sz = 0;
    int s;                      /* Raw socket */
    int pktsize;
    unsigned char outpack[1000];

    struct ether_addr eaddr;
    struct whereto_t whereto;   /* who to wake up */

    /* handle misc user options */
    opt_complementary = "=1";
    flags = getopt32(argv, "bi:p:", &ifname, &pass);
    if (flags & 4) /* -p */
        wol_passwd_sz = get_wol_pw(pass, wol_passwd);
    flags &= 1; /* we further interested only in -b [bcast] flag */

    /* create the raw socket */
    s = make_socket();

    /* now that we have a raw socket we can drop root */
    /* xsetuid(getuid()); - but save on code size... */

    /* look up the dest mac address */
    get_dest_addr(argv[optind], &eaddr);

    /* fill out the header of the packet */
    pktsize = get_fill(outpack, &eaddr, flags /* & 1 OPT_BROADCAST */);

    bb_debug_dump_packet(outpack, pktsize);

    /* Fill in the source address, if possible. */
#ifdef __linux__
    {
        struct ifreq if_hwaddr;

        strncpy(if_hwaddr.ifr_name, ifname, sizeof(if_hwaddr.ifr_name));
        ioctl_or_perror_and_die(s, SIOCGIFHWADDR, &if_hwaddr, "SIOCGIFHWADDR on %s failed", ifname);

        memcpy(outpack+6, if_hwaddr.ifr_hwaddr.sa_data, 6);

# ifdef DEBUG
        {
            unsigned char *hwaddr = if_hwaddr.ifr_hwaddr.sa_data;
            printf("The hardware address (SIOCGIFHWADDR) of %s is type %d  "
                   "%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x\n\n", ifname,
                   if_hwaddr.ifr_hwaddr.sa_family, hwaddr[0], hwaddr[1],
                   hwaddr[2], hwaddr[3], hwaddr[4], hwaddr[5]);
        }
# endif
    }
#endif /* __linux__ */

    bb_debug_dump_packet(outpack, pktsize);

    /* append the password if specified */
    if (wol_passwd_sz > 0) {
        memcpy(outpack+pktsize, wol_passwd, wol_passwd_sz);
        pktsize += wol_passwd_sz;
    }

    bb_debug_dump_packet(outpack, pktsize);

    /* This is necessary for broadcasts to work */
    if (flags /* & 1 OPT_BROADCAST */) {
        if (setsockopt_broadcast(s) != 0)
            bb_perror_msg("SO_BROADCAST");
    }

#if defined(PF_PACKET)
    {
        struct ifreq ifr;
        strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
        xioctl(s, SIOCGIFINDEX, &ifr);
        memset(&whereto, 0, sizeof(whereto));
        whereto.sll_family = AF_PACKET;
        whereto.sll_ifindex = ifr.ifr_ifindex;
        /* The manual page incorrectly claims the address must be filled.
           We do so because the code may change to match the docs. */
        whereto.sll_halen = ETH_ALEN;
        memcpy(whereto.sll_addr, outpack, ETH_ALEN);
    }
#else
    whereto.sa_family = 0;
    strcpy(whereto.sa_data, ifname);
#endif
    xsendto(s, outpack, pktsize, (struct sockaddr *)&whereto, sizeof(whereto));
    if (ENABLE_FEATURE_CLEAN_UP)
        close(s);
    return EXIT_SUCCESS;
}